440/1-76/048-b
Group I, Phase II AGENCV
DAUAS. TEXAS
Development Document for Interim
Final Effluent Limitations Guidelines
and Proposed New Source Performance
Standards for the
FORMING, FINISHING AND
SPECIALTY STEEL
Vol.l
Segments of the
IRON AND STEEL MANUFACTURING
Point Source Category
^r
in
UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
MARCH 1976
-------
DEVELOPMENT DOCUMENT
for
INTERIM FINAL
EFFLUENT LIMITATIONS GUIDELINES
and
PROPOSED NEW SOURCE PERFORMANCE STANDARDS
for the
FORMING, FINISHING AND SPECIALTY STEEL SEGMENTS
Of the
IRON AND STEEL MANUFACTURING
POINT SOURCE CATEGORY
Volume 1
Russell E. Train
Administrator
Andrew W. Briedenbach, Ph.D.
Assistant Administrator for Water
and Hazardous Materials
\
Ernst P. Hall
Acting Director, Effluent Guidelines Division
Edward L. Dulaney, P.E.
Project Officer
Patricia E. Williams, P.E.
Project Officer
John G. Williams
Assistant Project Officer
March, 1976
Effluent Guidelines Division
Office of Water and Hazardous Materials
U.S. Environmental Protection Agency
Washington, D.C. 20460
-------
ABSTRACT
This document presents the findings of an extensive study of
the hot forming, cold finishing and specialty steel
operations of the iron and steel industry for the purpose of
developing effluent limitations guidelines, federal
standards of performance, and pretreatment standards for
this segment of the industry to implement Sections 304, 306,
and 307 of the "Act".
Effluent limitations guidelines contained herein set forth
the effluent quality attainable through the application of
the best practicable control technology currently available
(BPCTCA) and the best available technology economically
achievable (BATEA) which must be achieved by existing point
sources by July 1, 1977, and July 1, 1983, respectively.
The standards of performance for new sources (NSPS) con-
tained therein set forth the effluent quality which is
achievable through the application of the best available
demonstrated control technology (BADCT), processes,
operating methods, or other alternatives.
Supporting data and rationale for development of the
effluent limitations guidelines and standards of performance
are contained in this report.
-------
CONTENTS
Section Page
I CONCLUSIONS 1
II RECOMMENDATIONS 3
BPCTCA Effluent Limitations 3
BATEA Effluent Limitations 14
NSPS Effluent Limitations 30
III INTRODUCTION 41
Purpose And Authority 41
Methods Used To Develop Limitations 42
Selection of Candidate Plants for Visits 44
General Description of the Industry 45
Product Classification 49
Anticipated Industrial Growth 70
General Description of the Operations 70
Steel Making Operations 70
Basic Oxygen Furnace 78
Vacuum Degassing 82
Continuous Casting 84
Hot Forming and Shaping Operations 86
Hot Forming Primary "^
Hot Forming Section 95
Hot Forming Flat "
Pipe and Tube 105
Surface Preparation and Scale Removal 1 1 3
Scale Removal 11 4
Acid Pickling 1 14
Continuous Strip Pickling 11 5
Batch Type Pickling ^5
Cold Forming and Coating Operations 122
Cold Rolling 122
Coatings 125
Alloy and Stainless Steel Pickling 135
and Descaling
Alkaline Cleaners 140
Wire Pickling and Coating 142
IV INDUSTRY SUBCATEGORIZATION 145
Rationale for Subcategorization - 147
Factors Considered
Manufacturing Processes 147
Final Products 148
-------
Raw Materials 149
Waste Water Characteristics 150
and Treatability
Gas Cleaning Equipment 151
Size and Age 151
Land Availability 152
Process Water Usage 152
V WATER USE AND WASTE CHARACTERISTICS 173
Steel Making Operations 173
Basic Oxygen Furnace 173
Vacuum Degassing 175
Continuous Casting and Pressure 175
Slab Molding
Hot Forming Operations 175
Hot Forming Primary 178
Hot Forming Section 181
Hot Forming Flat 181
Pipe and Tube 184
Pickling 186
Sulfuric Acid 187
Hydrochloric Acid 187
Cold Rolling 188
Hot Coating Operations 196
Galvanizing 197
Terne Coating 197
Miscellaneous Runoffs 199
Combination Acid Pickling 205
Scale Removal 205
Wire Coating 208
Continuous Alkaline Cleaning 208
VI SELECTION OF POLLUTANT PARAMETERS 211
Broad List of Pollutants 211
Rationale for Selection of Critical 224
Parameters by Operations 225
Environmental Impact of Pollutants 227
VII CONTROL AND TREATMENT TECHNOLOGY 241
Range of Technology and Current Practice 241
Base Level of Treatment 241
Basic Oxygen Furnace 241
Vacuum Degassing 255
Continuous Casting and Pressure 261
Slab Molding
Hot Forming Primary 280
Hot Forming Section 282
Hot Forming Flat - Plate Mills 300
Hot Forming Flat - Hot Strip 311
and Sheet Mills
VI
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Pipe and Tube Mills - 311
Hot Worked 311
Cold Worked 319
Pickling 319
Disposal Processes 319
Recycling Processes 323
Crystallization Processes 324
Spray Roaster Processes 328
Fluid-Bed Processes 329
Sulfuric Acid Processes 331
Hydrochloric Acid Processes 333
Cold Rolling Operations 376
Coating Operations 391
Pickling and Cleaning Operations - 400
Specialty Steel
Combination Acid Pickling 401
Scale Removal 407
Kolene Scale Removal 407
Hydride Scale Removal 414
Wire Pickling and Coating 414
Continuous Alkaline Cleaning 421
Specific Parameter Control 426
Reference Level of Treatment 447
Quantity and Quality of Treated Water 448
Required in the Steel Industry
VIII COST, ENERGY, AND NON-WATER QUALITY ASPECTS 455
Introduction 455
Costs 455
Basis of Cost Estimates 525
Reference Level and Intermediate Technology, 528
Energy and Non-Water Impact by Subcategory
Advanced Technology, Energy, and 566
Non-Water Impact by Subcategory
IX BPCTCA EFFLUENT LIMITATIONS GUIDELINES 581
Identification of Best Practicable 582
Control Technology Currently
Available - by Subcategory
Rationale for Selection of BPCTCA 613
Factors Considered
Discussion by Subcategory
X BATEA EFFLUENT LIMITATIONS GUIDELINES 663
Identification of the Best Available 664
Technology Economically Achievable -
by Subcategory
Rationale for Selection of BATEA 667
Factors Considered
Discussion by Subcategory
VI 1
-------
Cost Versus Effluent Reduction Benefits 733
XI NEW SOURCE PERFORMANCE STANDARDS (NSPS) 773
Introduction 773
NSPS Discharge Standard 774
XII ACKNOWLEDGEMENTS 777
XIII REFERENCES 779
XIV GLOSSARY 803
VI l 1
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FIGURES
Number Title Page
1 Raw Steel Production by Type of 71
Furnace and Grade - 1971
2 Flow Sheets Indicating General Principle 73
Steps in the Production of Stainless-
Steel Products
3 Schematic Cross Section - Heroult 74
Electric Arc Furnace
4 Schematic Arrangement of Furnace in Vacuum 77
Chamber Equipped charging and Mold Locks
5 Schematic Representation of a Consumable 79
Electrode Furnace
6 Basic Oxygen Furnace Gas Cleaning System 81
7 Vacuum Degassing Process Flow Diagram 83
8 Continuous Casting Process Flow Diagram 85
9-1 Hot Forming Process Flow Diagram 87
9-2 Cold Finishing Process Flow Diagram 88
10-1 Hot Forming Type I Process Flow Diagram 92
10-2 Hot Forming Type I Process Flow Diagram 93
11-1 Hot Forming Type III Process Flow Diagram 97
11-2 Wire-Making System Process Flow Diagram 98
12-1 Hot Forming Type II Process Flow Diagram 101
12-2 Hot Forming Type II Process Flow Diagram 103
13-1 Butt Weld Pipe Mill Process Flow Diagram 107
13-2 Seamless Tube Mill Process Flow Diagram 109
13-3 Tubing Mill Electric Resistance Welded 111
Process Flow Diagram
IX
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11-1 Continuous Strip Pickling Hydrochloric 116
Acid Process Flow Diagram
1U-2 Continuous Strip Pickling Sulfuric Acid 117
Process Flow Diagram
15 Batch Pickling Sulfuric Acid Process 118
Flow Diagram
16 Cold Rolling Mill Type I Process Flow 123
Diagram
17 Flat Products General Process Flow 126
Diagram
18 Hot Coating Galvanizing (ZN) Type I 130
Process Flow Diagram
19 Hot Coating Galvanizing (ZN) Type II 131
USS Steel Process
Process Flow Diagram
20 Hot Coating Galvanizing (ZN) Type II 132
Process Flow Diagram
21 Hot Coating Terne Plate Process 134
Flow Diagram
22 Combination Acid Pickling Process 137
Flow Diagram
23 Scale Removal Kolene Process Flow Diagram 138
24 Scale Removal Hydride Process Flow Diagram 139
25 Wire Pickling and Coating Process 141
Flow Diagram
26 Continuous Alkaline Cleaning Process 143
Flow Diagram
27 Basic Oxygen Furnace - Wastewater Treatment 257
System Water Flow Diagram - Plant D
28 Vacuum Degassing - Wastewater Treatment 259
System Water Flow Diagram - Plant E
29 Vacuum Degassing - Wastewater Treatment 260
System Water Flow Diagram - Plant G
-------
30 Continuous Casting - Wastewater Treatment 263
System Water Flow Diagram - Plant D
31 Continuous Casting - Wastewater Treatment 264
System Water Flow Diagram - Plant Q
32 Pressure Slab Molding - Wastewater Treat- 265
ment System Water Flow Diagram - Plant B
33 Hot Forming Wastewater Treatment System 267
Water Flow Diagram - Plant A-2
34 Hot Forming Wastewater Treatment System 268
Water Flow Diagram - Plant B-2
35 Hot Forming Wastewater Treatment System 269
Water Flow Diagram - Plant C-2
36 Hot Forming Wastewater Treatment System 270
Water Flow Diagram - Plant D-2
37 Hot Forming Wastewater Treatment System 271
Water Flow Diagram - Plant L-2
38 Hot Forming - Primary - Wastewater Treatment 273
System Water Flow Diagram - Plant E
39 Hot Forming - Primary - Wastewater Treatment 274
System Water Flow Diagram - Plant H
40 Hot Forming - Primary - Wastewater Treatment 275
System Water Flow Diagram - Plant K
41 Hot Forming - Primary - Wastewater Treatment 276
System Water Flow Diagram - Plant R
42 Hot Forming - Primary - Wastewater Treatment 277
System Water Flow Diagram - Plant D
43 Hot Forming - Primary - Wastewater Treatment 278
System Water Flow Diagram - Plant M
44 Hot Forming - Primary - Wastewater Treatment 279
System Water Flow Diagram - Plant Q
45 Hot Forming - Primary - Wastewater Treatment 285
System Water Flow Diagram - Plant E-2
46 Hot Forming - Section - Wastewater Treat- 286
ment System Water Flow Diagram - Plant F-2
XI
-------
47 Bar Mills Wastewater Treatment System 287
Water Flow Diagram - Plant G-2
48 Hot Forming - Section - Wastewater Treatment 288
System Water Flow Diagram - Plant H-2
49 Combined Wire, Rod, Pickling Wastewater Treat- 289
ment System Water Flow Diagram - Plant 1-2
50 Hot Forming - Section - Wastewater Treatment 292
System Water Flow Diagram - Plant C
51 Hot Forming - Section - Wastewater Treatment 293
System Water Flow Diagram - Plant H
52 Hot Forming - Section - Wastewater Treatment 294
System Water Flow Diagram - Plant K
53 Hot Forming - Section - Wastewater Treatment 295
System Water Flow Diagram - Plant M
54 Hot Forming - Section - Wastewater Treatment 296
System Water Flow Diagram - Plant 0
55 Hot Forming - Section - Wastewater Treatment 297
System Water Flow Diagram - Plant Q
56 Hot Forming - Section - Wastewater Treatment 298
System Water Flow Diagram - Plant R
57 Hot Forming - Section and Flat - Wastewater 299
Treatment System Water Flow Diagram -
Plant 0«
58 Hot Rolling Mill Wastewater Treatment 303
System Water Flow Diagram - Plant K-2
59 Hot Forming - Flat - Wastewater Treatment 304
System Water Flow Diagram - Plant F
60 Hot Strip Mill Wastewater Treatment 305
System Water Flow Diagram - Plant J-2
61 Hot Forming - Flat - Hot Strip and Sheet - 306
Wastewater Treatment System Water Flow
Diagram - Plant L-2
62 Hot Forming - Flat - Hot Strip and Sheet - 307
Wastewater Treatment System Water Flow
Diagram - Plant M-2
xn
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63 Hot Forming - Flat - Hot Strip and Sheet - 308
Wastewater Treatment System Water Flow
Diagram - Plant N-2
64 Hot Forming - Flat - Wastewater Treatment 309
System Water Flow Diagram - Plant E
65 Hot Forming - Flat - Wastewater Treatment 310
System Water Flow Diagram - Plant D
66 Pipe and Tube Mill Wastewater Treatment 314
System Water Flow Diagram - Plant GG-2
67 Pipe and Tube Mill Wastewater Treatment 315
System Water Flow Diagram - Plant II-2
68 Pipe and Tube Mill Wastewater Treatment 316
System Water Flow Diagram - Plant JJ-2
69 Pipe and Tube Mill Wastewater Treatment 317
System Water Flow Diagram - Plant KK-2
70 Pipe and Tube Mill Wastewater Treatment 318
System Water Flow Diagram - Plant HH-2
71 Sulfuric Acid Recovery Process 326
Flow Diagram
72 Pickling and Acid Recovery Process 327
Flow Diagram
73 HCl Regeneration Type I Process 330
Flow Diagram
74 HCl Regeneration Type II Fluid Bed 332
Roaster Process Flow Diagram
75 HCl Regeneration Type III Wet 334
Chemical Process
Process Flow diagram
76 Sulfuric Acid Pickling and Acid Recovery 340
Operation Wastewater Treatment System
Water Flow Diagram
77 Sulfuric Acid Recovery Wastewater Treatment 341
System Water Flow Diagram
78 Batch H.2SCW Pickling and Acid Recovery 342
Wastewater Treatment System Water
xi n
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Flow Diagram
79 Sulfuric Acid Pickling and Recovery Batch 343
Operation Wastewater Treatment System
Water Flow Diagram
80 H.2SO4 Pickling Line Wastewater Treatment 344
System Water Flow Diagram
81 Batch H.2SO4. Pickling Wastewater Treatment 345
System Water Flow Diagram
81-A Sulfuric Acid Batch Pickling - Wastewater 347
Treatment System Water Flow Diagram -
Plant R
82 Continuous Strip Pickling Wastewater Treatment 354
System Water Flow Diagram - Plant T-2
83 Continuous H2SO^ Pickling Wastewater Treatment 355
System Water Flow Diagram - Plant H-2
84 Continuous H2SO4. Pickling Wastewater Treatment 356
System Water Flow Diagram - Plant QQ-2
85 Continuous H2SO4_ Pickling And Cold Rolling 357
Wastewater Treatment System Water Flow
Diagram - Plant SS-2
86 Continuous H.2SO4 Pickling Wastewater Treatment 358
System Water Flow Diagram - Plant TT-2
87 Continuous H2SO^» Pickling Wastewater Treatment 359
System Water Flow Diagram - Plant WW-2
88 HCl Pickling Line Wastewater Treatment 355
System Water Flow Diagram - Plant U-2
89 HCl Pickling Line Wastewater Treatment 366
System Water Flow Diagram - Plant V-2
90 Hot Coating Line-Galvanizing Wastewater Treat- 357
ment System Water Flow Diagram - Plant V-2
91 Continuous HCl Pickling and Recovery 368
Wastewater Treatment System Water
Flow Diagram - Plant W-2
92 Cold Forming and HCl Pickling Wastewater Treat- 359
ment System Water Flow Diagram - Plant X-2
xiv
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93 HC1 Regeneration Wastewater Treatment 370
System Water Flow Diagram - Plant X-2
94 HC1 Pickling Line Wastewater Treatment 371
System Water Flow Diagram - Plant Y-2
95 HCl Regeneration Wastewater Treatment 372
System Water Flow Diagram - Plant Y-2
96 HCl Pickling Line Wastewater Treatment 373
System Water Flow Diagram - Plant Z-2
97 HCl Pickling Line Wastewater Treatment 374
System Water Flow Diagram - Plant AA-2
98 Cold Rolling and HCl Pickling Wastewater Treat- 375
ment System Water Flow Diagram - Plant BB-2
99 Cold Rolling Wastewater Treatment 380
System Water Flow Diagram - Plant DD-2
100 Cold Rolling Wastewater Treatment 381
System Water Flow Diagram - Plant EE-2
101 Cold Rolling Wastewater Treatment 382
System Water Flow Diagram - Plant FF-2
102 Cold Rolling - Direct Application - 383
Wastewater Treatment System Water Flow
Diagram - Plant W-2
103 Cold Rolling - Combination - Wastewater Treat- 384
ment System Water Flow Diagram - Plant YY-2
104 Cold Rolling - Recirculation - Wastewater Treat- 385
ment System Water Flow Diagram - Plant XX-2
105 Cold Rolling - Wastewater Treatment System 388
Water Flow Diagram - Plant D
106 Cold Rolling - Wastewater Treatment System 389
Water Flow Diagram - Plant I
107 Cold Rolling - Wastewater Treatment System 390
Water Flow Diagram - Plant P
108 Hot and Cold Coating Lines Wastewater Treatment 395
System Water Flow Diagram - Plant MM-2
109 Hot Coating Line Wastewater Treatment 395
xv
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System Water Flow Diagram - Plant NN-2
110 Hot Coating - Terne Plating Wastewater Treat- 397
ment System Water Flow Diagram - Plant OO-2
111 Hot Coating - Terne Plating Wastewater Treat- 398
ment System Water Flow Diagram - Plant TT-2
112 Combination Acid Pickling (Continuous) - 403
Wastewater Treatment System Water Flow
Diagram - Plant A
113 Combination Acid Pickling (Continuous) - 404
Wastewater Treatment System Water Flow
Diagram - Plant D
114 Combination Acid Pickling (Continuous) - 405
Wastewater Treatment System Water Flow
Diagram - Plant I
115 Combination Acid Pickling (Continuous) - 406
Wastewater Treatment System Water Flow
Diagram - Plant O
116 Combination Acid Pickling (Batch Pipe and 409
Tube) - Wastewater Treatment System Water
Flow Diagram - Plant U
117 Combination Acid Pickling (Other Batch) - 411
Wastewater Treatment System Water Flow
Diagram - Plant C
118 Combination Acid Pickling (Other Batch) - 412
Wastewater Treatment System Water Flow
Diagram - Plant F
119 Combination Acid Pickling (Other Batch) - 413
Wastewater Treatment System Water Flow
Diagram - Plant L
120 Kolene Scale Removal - Wastewater Treatment 417
System Water Flow Diagram - Plant L
121 Kolene Scale Removal - Wastewater Treatment 413
System Water Flow Diagram - Plant C
122 Kolene Scale Removal - Wastewater Treatment 419
System Water Flow Diagram - Plant Q
123 Hydride Scale Removal - Wastewater Treatment 420
xvi
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System Water Flow Diagram - Plant L
124 Wire Pickling - Wastewater Treatment 423
System Water Flow Diagram - Plant K
125 Wire Pickling and Coating - Wastewater 424
Treatment System Water Flow Diagram -
Plant L
126 Wire Pickling and Coating - Wastewater 425
Treatment System Water Flow Diagram -
Plant O
127 Continuous Alkaline Cleaning - Wastewater 428
Treatment System Water Flow Diagram -
Plant I
128 BPCTCA Model - B.O.F. (Wet Air 587
Pollution Controls)
129 BPCTCA Model - Vacuum Degassing 589
130 BPCTCA Model - Continuous Casting and 590
Pressure Slab Molding
131 Hot Forming/Primary Subcategory 593
BPCTCA Model
132 Hot Forming/Section Subcategory 595
BPCTCA Model
133 Hot Forming/Flat-Hot Strip and Sheet 597
Subcategory BPCTCA Model
134 Hot Forming/Flat-Plate Subcategory 599
BPCTCA Model
135-1 Pipe and Tube - Integrated - Subcategory 601
BPCTCA Model
135-2 Pipe and Tube - Isolated - Subcategory 603
BPCTCA Model
136 Pickling/H2SOj£ Batch - Concentrates and 605
Rinses Subcategory BPCTCA Model
137-1 Pickling/H2SOJ* Continuous - Concentrate and 607
Rinses Neutralization BPCTCA Model
137-2 Pickling/H_2SO4 - Continuous - Concentrates 609
xvn
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and Rinses - Acid Recovery Subcategory
BPCTCA Model
138 Pickling/HCl - Concentrates - Alternate I 611
Subcategory BPCTCA Model
139 Pickling/HCl - Rinse - Alternate I 612
Subcategory BPCTCA Model
140 Pickling/HCl - Concentrates and Rinses 615
Alternate II Subcategory BPCTCA Model
141 Cold Rolling - Recirculation Subcategory 617
BPCTCA Model
142 Cold Rolling - Combination Subcategory 619
BPCTCA Model
143 Cold Rolling - Direct Application 620
Subcategory BPCTCA Model
144 Hot Coating/Galvanizing Subcategory 623
BPCTCA Model
145 Hot Coatings - Terne Subcategory 625
BPCTCA Model
146-1 Combination Acid Pickling - Continuous - 629
Subcategory BPCTCA Model
146-2 Combination Acid Pickling - Batch Pipe and 631
Tube - Subcategory BPCTCA Model
146-3 Combination Acid Pickling - Other Batch - 633
Subcategory BPCTCA Model
147 Scale Removal - Kolene - Subcategory 635
BPCTCA Model
148 Scale Removal - Hydride - Subcateg'ory 637
BPCTCA Model
149 Wire Pickling and Coating Subcategory 639
BPCTCA Model
150 Continuous Alkaline Cleaning Subcategory 641
BPCTCA Model
151-1 BATEA Model - B.O.F. (Wet Air 669
Pollution Controls)
xvi 11
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151-2 Model Cost Effectiveness Diagram - B.O.F. 670
(Wet Air Pollution Controls)
152-1 BATEA Model - Vacuum Degassing 673
152-2 Model Cost Effectiveness Diagram - 674
Vacuum Degassing
153-1 BATEA Model - Continuous Casting and 677
Pressure Slab Molding
153-2 Model Cost Effectiveness Diagram - 678
Continuous Casting and Pressure
Slab Molding
154-1 Hot Forming/Primary Subcategory 681
BATEA Model
154-2 Model Cost Effectiveness Diagram 682
Hot Forming - Primary Subcategory
154A Model Cost Effectiveness Diagram 683
Hot Forming - Primary - Specialty Steel
Subcategory
155-1 Hot Forming/Section Subcategory 685
BATEA Model
155-2 Model Cost Effectiveness Diagram 686
Hot Forming - Section Subcategory
155A Model Cost Effectiveness Diagram 687
Hot Forming - Section - Specialty Steel
Subcategory
156-1 Hot Forming/Flat - Hot Strip and 689
Sheet Subcategory BATEA Model
156-2 Model Cost Effectiveness Diagram 690
Hot Forming - Flat - Hot Strip and
Sheet Subcategory
156A Model Cost Effectiveness Diagram - 691
Hot Forming - Flat - Specialty Steel
Subcategory
157-1 Hot Forming/Flat - Plate Subcategory 693
BATEA Model
157-2 Model Cost Effectiveness Diagram 694
xix
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Hot Forming - Flat Plate Sutcategory
157A Model Cost Effectiveness Diagram 695
Hot Forming - Flat Plate - Specialty
Steel Subcategory
158-1 Pipe and Tube - Integrated - Subcategory 697
BATEA Model
158-2 Model Cost Effectiveness Diagram 698
Pipe and Tubes Subcategory
159-1 Pipe and Tubes - Isolated - Subcategory 701
BATEA Model
159-2 Model Cost Effectiveness Diagram 702
Pipe and Tubes - Isolated - Subcategory
160-1 Pickling/H^SOl - Batch - Concentrates and 705
Rinse Subcategory BATEA Model
160-2 Model Cost Effectiveness Diagram 706
Pickling - Sulfuric Acid - Batch -
Subcategory
161-1 Pickling/H^SOJ* - Continuous - Concentrates 709
and Rinses - Neutralization Subcategory
BATEA Model
161-2 Model Cost Effectiveness Diagram 710
Pickling - Sulfuric Acid - Continuous -
Neutralization Subcategory
162-1 Pickling/H2SO4 - Continuous - Concentrates 713
and Rinses - Acid Recovery Subcategory
BATEA Model
162-2 Model Cost Effectiveness Diagram 714
Pickling - Sulfuric Acid - Continuous -
Acid Recovery Subcategory
163-1 Pickling/HCl - Concentrated - Alternate I 717
Subcategory BATEA Model
163-2 Model Cost Effectiveness Diagram 718
Pickling Hydrochloric Acid - Concentrated
Subcategory - Alternate I
164-1 Pickling/HCl - Rinse - Alternate I 719
Subcategory BATEA Model
xx
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164-2 Model Cost Effectiveness Diagram 720
Pickling - Hydrochloric Acid - Rinse
Subcategory - Alternate I
165-1 Pickling/HCl Concentrates and Rinses 723
Alternate II Subcategory BATEA Model
165-2 Model Cost Effectiveness Diagram 724
Pickling - Hydrochloric Acid - Concentrated
and Rinse - Subcategory - Alternate II
166-1 Cold Rolling - Recirculation Subcategory 727
BATEA Model
166-2 Model Cost Effectiveness Diagram 728
Cold Rolling - Recirculation Subcategory
167-1 Cold Rolling - Combination Subcategory 731
BATEA Model
167-2 Model Cost Effectiveness Diagram Cold 732
Rolling - Combination Subcategory
168-1 Cold Rolling - Direct Application 735
Subcategory BATEA Model
168-2 Model Cost Effectiveness Diagram Cold 736
Rolling - Direct Application Subcategory
169-1 Hot Coatings - Galvanizing Subcategory 739
BATEA Model
169-2 Model Cost Effectiveness Diagram Hot 740
Coating - Galvanizing - Subcategory
170-1 Hot Coatings - Terne Subcategory 743
BATEA Model
170-2 Model Cost Effectiveness Diagram 744
Hot Coating - Terne Subcategory
171 Miscellaneous Runoffs Subcategory 743
BATEA Model
172-1-1 BATEA Model - Combination Acid Pickling 750
(Continuous) Subcategory
172-1-2 Model Cost Effectiveness Diagram - 751
Combination Acid Pickling (Continuous)
Subcategory
xxi
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172-2-1 BATEA Model - Combination Acid Pickling 753
(Batch Pipe and Tube) Subcategory
172-2-2 Model Cost Effectiveness Diagram - 754
Combination Acid Pickling (Batch
Pipe and Tube) Subcategory
172-3-1 BATEA Model - Combination Acid Pickling 757
(Other Batch) Subcategory
172-3-3 Model cost Effectiveness Diagram - 758
Combination Acid Pickling (Other
Batch) Subcategory
173-1 BATEA Model - Kolene Scale Removal 760
Subcategory
173-2 Model Cost Effectiveness Diagram - 761
Kolene Scale Removal Subcategory
174-1 BATEA Model - Hydride scale Removal 763
Subcategory
174-2 Model Cost Effectiveness Diagram - 764
Hydride Scale Removal Subcategory
175-1 BATEA Model - Wire Pickling and Coating 766
Subcategory
175-2 Model Cost Effectiveness Diagram - 767
Wire Pickling and Coating Subcategory
176-1 BATEA Model - Continuous Alkaline 769
Cleaning Subcategory
176-2 Model Cost Effectiveness Diagram - 770
Continuous Alkaline Cleaning Subcategory
xxn
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TABLES
Dumber Title Page
1 United States Annual Steel Ingot Ton 46
Production
2 Alloy and Stainless Steel Plants - 1972 47
3 Product Classification by SIC Code (3312) 50
3 Product Classification by SIC Code (cont'd) 51
U Product Classification by SIC Code (3315) 52
5 Product Classification by SIC Code (3316) 53
6 Product Classification by SIC Code (3317) 54
7 Rationale for Plant Selections 55
8 Industrial Categorization and Survey 66
Requirements
9 Plant Age and Size - Basic Oxygen Furnace 154
10 Plant Age and Size - Vacuum Degassing 155
11 Plant Age and Size - Continuous Casting 156
and Pressure Slab Molding
12 Plant Age and Size - Hot Forming Primary 157
13 Plant Age and Size - Hot Forming Section 158
14 Plant Age and Size - Hot Forming Flat 159
15 Plant Age and Size - Pipe and Tubes 160
16 Plant Age and Size - Pickling Sulfuric 161
Acid - Batch
16-1 Plant Age and Size - Pickling - Sulfuric 162
Acid - Continuous
17 Plant Age and Size - Hydrochloric Acid - 153
Batch and Continuous
18 Plant Age and Size - Cold Rolling 164
xxm
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19 Plant Age and Size - Hot Coating - Galvanizing 165
20 Plant Age and Size - Hot Coating - Terne 166
21 Plant Age and Size - Miscellaneous Runoffs 167
22 Plant Age and Size - Combination Acid Pickling 169
23 Plant Age and Size - Scale Removal 170
24 Plant Age and Size - Wire Pickling and Coating 171
25 Plant Age and Size - Continuous Alkaline Cleaning 172
26 Characteristics of Basic Oxygen Furnace Wastes 174
27 Characteristics of Vacuum Degassing Wastes 174
28 Characteristics of Continuous Casting and 176
Pressure Slab Molding Plant Wastes
29 Characteristics of Hot Forming Primary 176
Plant Wastes
29-A Characteristics of Hot Forming Primary 179
Plant Wastes - Specialty Steel
30 Characteristics of Hot Forming Section 179
Plant Wastes
30-A Characteristics of Hot Forming Section 180
Plant Wastes - Specialty Steel
31 Characteristics of Hot Forming Flat 183
Plant Wastes
31-A Characteristics of Hot Forming Flat 183
Plant Wastes - Specialty Steel
32 Characteristics of Pipe and Tubes - 185
Hot worked Plant Wastes
33 Characteristics of Pipe and Tubes - 185
Cold Worked Plant Wastes
3H Characteristics of Pickling - Sulfuric 185
Acid Batch Plant Wastes - Spent
Pickle Liquor
34-A Characteristics of Pickling - Sulfuric 189
xxiv
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Acid Batch Plant Wastes - Specialty Steel
34-1 Characteristics of Pickling - Sulfuric 190
Acid - Continuous - Spent Pickle Liquor -
Rinses - Fume Hood Scrubbers
35 Characteristics of Pickling - Sulfuric 190
Acid Batch Plant Wastes - Rinses
36 Characteristics of Pickling - Hydrochloric 191
Acid Batch Plant Wastes - Spent Pickle
Liquor
37 Characteristics of Pickling - Hydrochloric 191
Acid Batch Plant Wastes - Rinses
38 Characteristics of Pickling - Hydrochloric 192
Acid Continuous Plant Wastes - Spent
Pickle Liquor
39 Characterizatics of Pickling - Hydrochloric 192
Acid Continuous Plant Wastes -
Regeneration Absorber Scrubber
40 Characteristics of Pickling - Hydrochloric 193
Acid Continuous Plant Wastes - Rinses
41 Characteristics of Pickling - Hydrochloric 193
Acid Continuous Plant Wastes - Fume
Hood Scrubbers
42 Characteristics of Cold Rolling 195
Plant Wastes
42-A Characteristics of Cold Rolling Plant 195
Wastes - Specialty Steel
43 Characteristics of Hot Coatings - 198
Galvanizing Plant Wastes
44 Characteristics of Hot Coatings - Terne 198
Plate Plant Wastes
45 Characteristics of Miscellaneous Runoffs 202
46 Characteristics of Combination Acid Pickling - 206
Batch and Continuous - Plant Wastes
47 Characteristics of Scale Removal - Kolene - 209
Plant Wastes
xxv
-------
48 Characteristics of Scale Removal - Hydride - 209
Plant Wastes
49 Characteristics of Wire Pickling and Coating 210
Plant Wastes
50 Characteristics of Continuous Alkaline 210
Cleaning Plant Wastes
51 Basic Oxygen Furnace Operation Parameters 212
52 Vacuum Degassing Operation Parameters 212
53 Continuous Casting and Pressure Slab 213
Molding Operation Parameters
54 Hot Forming Operation Parameters 214
55 Pipe and Tubes Operation Parameters 214
56 Pickling Operation Parameters 215
57 Cold Rolling Operation Parameters 215
58 Hot Coatings - Galvanizing Operation 216
Parameters
59 Hot Coatings - Terne Plant Operation 217
Parameters
60-1 Miscellaneous Runoffs - Storage Piles - 218
Coal - Parameters
60-2 Miscellaneous Runoffs - Storage Piles - 219
Stone - Parameters
60-3 Miscellaneous Runoffs - Storage Piles - 220
Ore - Parameters
60-4 Miscellaneous Runoffs - Slagging Operations - 221
Blasts Furnace Slag Parameters
61 Combination Acid Pickling Operation Parameters 222
62 Scale Removal Operation Parameters 222
63 Wire Pickling and Coating Operation Parameters 223
64 Continuous Alkaline Cleaning Operation 223
Parameters
xxvi
-------
65 Wastewater Treatment Practices of Plants 242
Visited in Study
66 Control and Treatment Technology - 459
Basic Oxygen Furnace
67 Control and Treatment Technology - Vacuum 460
Degassing
68 Control and Treatment Technology - 461
Continuous Casting and Pressure Slab Molding
69 Control and Treatment Technology - 462
Hot Forming - Primary
70 Control and Treatment Technology - 465
Hot Forming - Section
71-1 Control and Treatment Technology - 468
Hot Forming - Flat - Hot Strip and Sheet
71-2 Control and Treatment Technology - 471
Hot Forming - Flat - Plate
72-1 Control and Treatment Technology - 474
Pipe and Tubes - Integrated
72-2 Control and Treatment Technology - 477
Pipe and Tubes - Isolated
73 Control and Treatment Technology - 479
Pickling - Sulfuric Acid - Batch
Concentrates and Rinses
74-1 Control and Treatment Technology - 480
Pickling - Sulfuric Acid - Continuous -
Concentrates and Rinses - Neutralization
74-2 Control and Treatment Technology - 482
Pickling - Continuous - Concentrates
and Rinses - Acid Recovery
75 Control and Treatment Technology - 483
Pickling - Hydrochloric Acid -
Concentrates - Alternate I
76 Control and Treatment Technology - 485
Pickling - Hydrochloric Acid - Rinses -
Alternate I
-------
77 Control and Treatment Technology - Pickling - 486
Hydrochloric Acid - Concentrates and
Rinses - Alternate II
78 Control and Treatment Technology - 487
Cold Rolling - Recirculation
79 Control and Treatment Technology - 488
Cold Rolling - Combination
80 Control and Treatment Technology - 489
Cold Rolling - Direct Application
81 Control and Treatment Technology - 490
Hot Coatings - Galvanizing
82 Control and Treatment Technology - 492
Hot Coatings - Terne
83 Control and Treatment Technology - 494
Miscellaneous Runoffs
84 Control and Treatment Technology - 496
Combination Acid Pickling
85 Control and Treatment Technology - 497
Scale Removal
86 Control and Treatment Technology - 498
Wire Pickling and Coating
87 Control and Treatment Technology - 499
Continuous Alkaline Cleaning
88 Plant Raw and Effluent Waste Loads - 256
Basic Oxygen Furnace
89 Plant Raw and Effluent Waste Loads - 258
Vacuum Degassing
90 Plant Raw and Effluent Waste Loads - 262
Continuous Casting and Pressure
Slab Molding
91 Plant Raw and Effluent Waste Loads - 266
Hot Forming - Primary
91-A Plant Raw and Effluent Waste Loads - 2?2
xxvi 11
-------
Hot Forming - Primary - Specialty Steel
92 Plant Raw and Effluent Waste Loads - 283
Hot Forming - Section
92-A Plant Raw and Effluent Waste Loads - 290
Hot Forming - Section - Specialty Steel
93 Plant Raw and Effluent Waste Loads - 301
Hot Forming - Flat
93-A Plant Raw and Effluent Waste Loads - 302
Hot Forming - Flat - Specialty Steel
9H Plant Raw and Effluent Waste Loads - 312
Pipe and Tubes
95 Plant Raw and Effluent Waste Loads - 336
Pickling - H2SO4 - Batch Concentrated
96 Plant Raw and Effluent Waste Loads - 338
Pickling - H2SOJ* - Batch Rinse
96-A Plant Raw and Effluent Waste Loads - 346
Pickling - H2SCW - Batch Specialty
Steel
97-1 Plant Raw and Effluent Waste Loads - 349
Pickling - H2SOjt - Continuous Concentrate
97-2 Plant Raw and Effluent Waste Loads - 351
Pickling - H2SO£ - Continuous Rinse
97-3 Plant Raw and Effluent Waste Loads - 353
Pickling - H2SO4. - Continuous Fume
Hood scrubber
98 Plant Raw and Effluent Waste Loads - 361
Pickling - HCl - Concentrate Batch
and Continuous
99 Plant Raw and Effluent Waste Loads - 363
Pickling - HCl Rinse - Batch and Continuous
100 Plant Raw and Effluent Waste Loads - 378
Cold Rolling
100-A Plant Raw and Effluent Waste Loads - 387
Cold Rolling - Specialty Steel
xxix
-------
101 Plant Raw and Effluent Waste Loads - 393
Hot Coatings - Galvanizing
102 Plant Raw and Effluent Waste Loads - 394
Hot Coatings - Terne Plate
103 Plant Raw and Effluent Waste Loads - 399
Miscellaneous Runoffs
104-1 Plant Raw and Effluent Waste Loads - 402
Combination Acid Pickling - Continuous
104-2 Plant Raw and Effluent Waste Loads - 408
Combination Acid Pickling - Batch Pipe
and Tube
104-3 Plant Raw and Effluent Waste Loads - 410
Combination Acid Pickling - Other Batch
105 Plant Raw and Effluent Waste Loads - 415
Scale Removal - Kolene - Hydride
106 Plant Raw and Effluent Waste Loads - 422
Wire Pickling and Coating
107 Plant Raw and Effluent Waste Loads - 427
Continuous Alkaline Cleaning
108 Industry Group - Water Intake 449
112 Plant Water Effluent Treatment Costs - 500
Hot Forming - Primary
112-A Plant Water Effluent Treatment Costs - 501
Hot Forming - Primary - Specialty Steel
113 Plant Water Effluent Treatment Costs - 502
Hot Forming - section
113-A Plant Water Effluent Treatment Costs - 503
Hot Forming - Section - Specialty Steel
114 Plant Water Effluent Treatment Costs - 504
Hot Forming - Flat
114-A Plant Water Effluent Treatment Costs - 505
Hot Forming - Flat - Specialty Steel
115 Plant Water Effluent Treatment Costs - 506
Pipe and Tubes
xxx
-------
116 Plant Water Effluent Treatment Costs - 507
Pickling - Sulfuric Acid - Batch - Concentrate
117 Plant Water Effluent Treatment Costs - 508
Pickling - Sulfuric Acid - Batch - Rinse
117-A Plant Water Effluent Treatment Costs - 509
Pickling - Sulfuric Acid - Batch - Concentrate
and Rinse - Specialty Steel
118 Plant Water Effluent Treatment Costs - 510
Pickling - Continuous Sulfuric Acid -
Concentrate and Rinse
118-1 Plant Water Effluent Treatment Costs - 511
Pickling - Sulfuric Acid - Continuous -
Concentrate
118-2 Plant Water Effluent Treatment Costs - 512
Pickling - Sulfuric Acid - Continuous - Rinse
118-3 Plant Water Effluent Treatment Costs - 513
Pickling - Sulfuric Acid - Continuous -
Fume Hood Scrubber
119 Plant Water Effluent Treatment Costs - 514
Pickling - Hydrochloric Acid - Concentrate
120 Plant Water Effluent Treatment Costs - 515
Pickling - Hydrochloric Acid - Rinses -
Batch and Continuous
121 Plant Water Effluent Treatment Costs - 516
Cold Rolling
121-A Plant Water Effluent Treatment Costs - 517
Cold Rolling - Specialty Steel
122 Plant Water Effluent Treatment Costs - 518
Hot Coatings - Galvanizing
123 Plant Water Effluent Treatment Costs - 519
Hot Coatings - Terne Plate
124 Plant Water Effluent Treatment Costs - 520
Miscellaneous Runoffs
125 Plant Water Effluent Treatment Costs - 521
Combination Acid Pickling (Continuous,
Batch Pipe and Tube, Other Batch)
xxxi
-------
126 Plant Water Effluent Treatment Costs - 522
Kolene and Hydride - Scale Removal
127 Plant Water Effluent Treatment Costs - 523
Wire Pickling and Coating
128 Plant Water Effluent Treatment Costs - 524
Continuous Alkaline Cleaning
129 Water Effluent Treatment Costs - 529
Basic Oxygen Furnace
130 Water Effluent Treatment Costs - 531
Vacuum Degassing
131 Water Effluent Treatment Costs - 532
Continuous Casting and Pressure
Slab Molding
132 Water Effluent Treatment Costs - 534
Hot Forming - Primary
132-A Water Effluent Treatment Costs - 535
Hot Forming - Primary - Specialty Steel
133 Water Effluent Treatment Costs - 536
Hot Forming - Section
133-A Water Effluent Treatment Costs - 537
Hot Forming - Section - Specialty Steel
134-1 Water Effluent Treatment Costs - 539
Hot Forming - Flat - Hot Strip and Sheet
134-2 Water Effluent Treatment Costs - 540
Hot Forming - Flat - Plate
134-A-1 Water Effluent Treatment Costs - 541
Hot Forming - Flat - Plate - Specialty Steel
134-A-2 Water Effluent Treatment Costs - 542
Hot Forming - Flat - Hot Strip and
Sheet - Specialty Steel
135-1 Water Effluent Treatment Costs - 544
Pipe and Tubes - Integrated
135-2 Water Effluent Treatment Costs - 545
Pipe and Tubes - Isolated
xxx 11
-------
136 Water Effluent Treatment Costs - 547
Pickling - H2SO4 - Batch - Concentrate
and Rinse
137 Water Effluent Treatment Costs - 548
Pickling - H2SO4 - Continuous -
Concentrates and Rinses - Neutralization
137-1 Model Effluent Treatment Costs - 549
Pickling - H2SO4 - Continuous -
Concentrates and Rinses - Acid Recovery
138 Water Effluent Treatment Costs - 552
Pickling - Hydrochloric Acid - Rinses -
Alternate I
139 Water Effluent Treatment Costs - 553
Pickling - Hydrochloric Acid - Concentrates -
Alternate I
140 Water Effluent Treatment Costs - 554
Pickling - Hydrochloric Acid - Concentrates
and Rinses - Alternate II
141 Water Effluent Treatment Costs - 555
Cold Rolling - Recirculation
142 Water Effluent Treatment Costs - 557
Cold Rolling - Combination
143 Water Effluent Treatment Costs - 553
Cold Rolling - Direct Application
144 Water Effluent Treatment Costs - 550
Cold Rolling - Galvanizing
145 Water Effluent Treatment Costs - 551
Cold Rolling - Terne
146-1 Water Effluent Treatment Costs - 552
Miscellaneous Runoffs - Coal Storage Pile
146-2 Water Effluent Treatment Costs - 553
Miscellaneous Runoffs - stone Storage Pile
146-3 Water Effluent Treatment Costs - 554
Miscellaneous Runoffs - Ore Storage Pile
146-4 Water Effluent Treatment Costs - 555
Miscellaneous Runoffs - Casting and Slagging
xxxm
-------
147-1 Water Effluent Treatment Costs - 567
Combination Acid Pickling - Continuous
147-2 Water Effluent Treatment Costs - 568
Combination Acid Pickling - Batch Pipe
and Tube
147-3 Water Effluent Treatment Costs - 569
Combination Acid Pickling - Other Batch
148-1 Water Effluent Treatment Costs - 570
Scale Removal - Kolene
148-2 Water Effluent Treatment Costs - 571
Scale Removal - Hydride
149 Water Effluent Treatment Costs - 572
Wire Pickling and Coating
150 Water Effluent Treatment Costs - 573
Continuous Alkaline Cleaning
151 Effluent Limitations Guidelines - BPCTCA - 586
B.O.F. (Wet Air Pollution Controls)
152 Effluent Limitations Guidelines - 588
Vacuum Degassing
153 Effluent Limitations Guidelines - 590
Continuous Casting and Pressure
Slab Molding
154 Effluent Limitations Guidelines - Hot 592
Forming Primary - BPCTCA
155 Effluent Limitations Guidelines - Hot 594
Forming Section - BPCTCA
156 Effluent Limitations Guidelines - Hot 596
Forming Flat - Hot Strip and Sheet -
BPCTCA
157 Effluent Limitations Guidelines - Hot 598
Forming Flat - Plate - BPCTCA
158 Effluent Limitations Guidelines - Pipe 600
and Tubes - Integrated - BPCTCA
158-1 Effluent Limitations Guidelines - 602
Pipe and Tubes - Isolated - BPCTCA
xxxi v
-------
159 Effluent Limitations Guidelines - 604
Pickling - Sulfuric Acid - Batch
Concentrates and Rinses - BPCTCA
160 Effluent Limitations Guidelines - 606
Pickling - Sulfuric Acid - Continuous -
Concentrates and Rinses - Neutralization -
BPCTCA
161 Effluent Limitations Guidelines - 608
Pickling - Sulfuric Acid - Continuous -
Concentrates and Rinses - Acid Recovery
162 Effluent Limitations Guidelines - 610
Pickling - Hydrochloric Acid -
Concentrates and Rinses - Alternate I -
BPCTCA
163 Effluent Limitations Guidelines - 614
Pickling - Hydrochloric Acid - Concentrates
and Rinses - Alternate II - BPCTCA
164 Effluent Limitations Guidelines - 616
Cold Rolling - Recirculation - BPCTCA
165 Effluent Limitations Guidelines - 618
Cold Rolling - Combination - BPCTCA
166 Effluent Limitations Guidelines - 620
Cold Rolling - Direct Application -
BPCTCA
167 Effluent Limitations Guidelines - Hot 622
Coatings - Galvanizing - BPCTCA
168 Effluent Limitations Guidelines - Hot 624
Coatings - Terne - BPCTCA
169 Effluent Limitations Guidelines - 626
Miscellaneous Runoffs - BPCTCA
170-1 Effluent Limitations Guidelines - 628
Combination Acid Pickling (Continuous) -
BPCTCA
170-2 Effluent Limitations Guidelines - 630
Combination Acid Pickling (Batch
Pipe and Tube) - BPCTCA
170-3 Effluent Limitations Guidelines - 632
xxxv
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Combination Acid Pickling (Other Batch) -
BPCTCA
171-1' Effluent Limitations Guidelines - 634
Kolene Scale Removal - BPCTCA
171-2 Effluent Limitations Guidelines - 636
Hydride Scale Removal - BPCTCA
172 Effluent Limitations Guidelines - 638
Wire Pickling and Coating - BPCTCA
173 Effluent Limitations Guidelines - 640
Continuous Alkaline Cleaning - BPCTCA
174 Effluent Limitations Guidelines - 668
B.O.F. (Wet Air Pollution Controls) - BATEA
175 Effluent Limitations Guidelines - 672
Vacuum Degassing - BATEA
176 Effluent Limitations Guidelines - 676
Continuous Casting and Pressure
Slab Molding - BATEA
177 Effluent Limitations Guidelines - Hot 680
Forming Primary - BATEA
178 Effluent Limitations Guidelines - 684
Hot Forming Section - BATEA
179 Effluent Limitations Guidelines - 688
Hot Forming Flat - Hot Strip and
Sheet - BATEA
180 Effluent Limitations Guidelines - 692
Hot Forming Flat - Plate - BATEA
181 Effluent Limitations Guidelines - 696
Pipe and Tubes - Integrated - BATEA
181-1 Effluent Limitations Guidelines - 700
Pipe and Tubes - Isolated - BATEA
182 Effluent Limitations Guidelines - 704
Pickling - Sulfuric Acid - Batch
Concentrates and Rinses - Acid Recovery -
BATEA
183 Effluent Limitations Guidelines - 708
xxxvi
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Pickling - Sulfuric Acid - Continuous -
Concentrates and Rinses - Neutralization
184 Effluent Limitations Guidelines - 712
Pickling - Sulfuric Acid - Continuous -
Concentrates and Rinses - Acid Recovery
185 Effluent Limitations Guidelines - 715
Pickling - Hydrochloric Acid -
Concentrates and Rinses - Alternate I -
BATEA
186 Effluent Limitations Guidelines - 722
Pickling - Hydrochloric Acid - Concentrates
and Rinses - Alternate II - Neutralization -
BATEA
187 Effluent Limitations Guidelines - 726
Cold Rolling - Recirculation - BATEA
188 Effluent Limitations Guidelines - 730
Cold Rolling - Combination - BATEA
189 Effluent Limitations Guidelines - 734
Cold Rolling - Direct Application - BATEA
190 Effluent Limitations Guidelines - 733
Hot Coatings - Galvanizing - BATEA
191 Effluent Limitations Guidelines - 742
Hot Coatings - Terne - BATEA
192 Effluent Limitations Guidelines - 747
Miscellaneous Runoffs - BATEA
193-1 Effluent Limitations Guidelines - 749
BATEA - Combination Acid Pickling
(Continuous)
193-2 Effluent Limitations Guidelines - 752
BATEA - Combination Acid Pickling
(Batch Pipe and Tube)
193-3 Effluent Limitations Guidelines - 755
BATEA - Combination Acid Pickling
(Other Batch)
194-1 Effluent Limitations Guidelines - 759
BATEA - Kolene Scale Removal
xxxvn
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194-2 Effluent Limitations Guidelines - 762
BATEA - Hydride Scale Removal
195- Effluent Limitations Guidelines - 765
BATEA - Wire Pickling and Coating
196 Effluent Limitations Guidelines - 768
BATEA - Continuous Alkaline Cleaning
197 Hot Forming, Cold Finishing and Specialty 771
Steel Operations Projected Total Costs
for Related Subcategories
198 Metric Units - Conversion Table 815
199 Classification by Subcategory 816
xxxvill
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SECTION I
CONCLUSIONS
For the purpose of establishing effluent guidelines and
standards of performance for the forming, finishing and
specialty steel operations of the iron and steel industry,
the industry was divided into subcategories as follows:
G. Basic Oxygen Furnace (Wet Air Pollution Control)
Subcategory
K. Vacuum Degassing Subcategory
L. Continuous Casting and Pressure Slab Molding Subcategory
M. Hot Forming Primary Subcategory
N. Hot Forming Section Subcategory
O. Hot Forming Flat Subcategory
P. Pipe and Tubes Subcategory
Q. Pickling-Sulfuric Acid-Batch and Continuous Subcategory
R. Pickling-Hydrochloric Acid-Batch and Continuous
Subcategory
S. cold Rolling Subcategory
T. Hot Coat-Galvanizing Subcategory
U. Hot Coat-Terne Subcategory
V. Miscellaneous Runoffs Subcategory
W. Combination Acid Pickling (Batch and Continuous)
Subcategory
X. Scale Removal (Kolene and Hydride) Subcategory
Y. Wire Coating and Pickling Subcategory
Z. Continuous Alkaline Cleaning Subcategory
NOTE: Subcategories A through L relate to the Steelmaking
Segment which was discussed in an earlier Development
Document, EPA-H40/l-7U-024-a. Subcategories G, K
and L appearing in this Development Document relate
to the specialty steel industry.
The selection of these subcategories was based upon distinct
differences in type of products produced, production pro-
cesses, raw materials used, wastewater volumes generated,
pollutants generated, and control and treatment technologies
employed. Subsequent waste characterizations of individual
plants substantiated the validity of this subcategorization.
The waste characterizations of individual plants visited
during this study, and the guidelines developed as a result
of the data collected, relate only to the aqueous discharges
from the facilities, excluding noncontact cooling waters.
The effluent guidelines established in this study are not
dependent upon the raw water intake quality. The
-------
limitations were derived by determining the average of the
discharge loads from the best plants (for BPT) and the
discharge load from the best plant (for BAT). The allowable
effluent load for a specific process or operation is
determined by multiplying the production rate of the process
product by the effluent limitation for each specific
pollutant parameter controlled for that operation.
The plant raw wasteload reflects the pickup of contaminants
across a production process in a single pass. It was
necessary to establish the raw waste load in this manner in
order to obtain a meaningful comparison of wastes generated
during production from the range of plants surveyed. Some
plants utilized once-through water systems, while many
others used varying degrees of reuse and/or recycle.
The capital investment which will be required to meet the
BPCTCA regulations contained herein is $1.14 billion above
the reference level. To meet the BATEA regulations will
require an additional investment of $584 million. The total
cost to the steel industry of this regulation, the
regulation published on June 28, 1974 for the carbon
steelmaking segment, and the electroplating regulation x(for
cold coating operations) will be $1.31 billion to meet
BPCTCA, and an additional $716 million to meet BATEA.
The incremental annual operating and capital costs of this
regulation will be $155 million to meet the BPCTCA
limitations, with an additional $119 million required to
meet the BATEA limitations. For the industry as a whole,
the total cost of EPCTCA compliance will be $201 million
annually, while BATEA will cost an additional $164 million
annually. Of these amounts, the costs to the specialty
steel segment are approximately 10% of the total. Costs may
vary depending upon such factors as location, availability
of land and chemicals, flow to be treated, treatment
technology selected where competing alternatives exist, and
the extent of preliminary modifications required to accept
the necessary control and treatment devices.
-------
SECTION II
RECOMMENDATIONS
The effluent limitation guidelines for the forming,
finishing and specialty steel segments of the iron and steel
industry, representing the effluent quality obtainable
through the application of the appropriate treatment and
control technology available for each industry subcategory,
are summarized as follows:
Part I - Best Practicable Control Technology Currently
Available (BPCTCA - 1977)
Part II - Best Achievable Treatment Economically Achievable
(BATEA - 1983)
Part III - Best Available Demonstrated Control Technology
(BADCT - New Sources)
PART I - BEST PRACTICABLE CONTROL TECHNOLOGY CURRENTLY
AVAILABLE (BPCTCA - 1977)
The effluent limitations guidelines representing the
effluent quality obtainable by existing point sources
through the application of the best practicable control
technology currently available (BPCTCA) for each industry
subcategory are as follows:
G. Basic Oxygen Furnace (Wet Air Pollution Control Methods;
BPCTCA Effluent Limitations
Units: kg pollutant per kkg of product
or: Ib pollutant per 1,000 Ib of product
Maximum Average of
Maximum for any Daily Values for any
Pollutant One Day Period Period of 30
Parameter Shall Not Exceed Consecutive Days
Suspended Solids 0.0312 0.010U
pH 6.0 to 9.0
K. Vacuum Degassing
BPCTCA Effluent Limitations
-------
Units:
or:
Pollutant
Parameter
Suspended Solids
PH
kg pollutant per kkg of product
Ib pollutant per 1,000 Ib of product
Maximum for any
One Day Period
Shall Not Exceed
0.0156
Maximum Average of
Daily Values for any
Period of 30
Consecutive Days
0.0052
6.0 to 9.0
L. Continuous Casting and Pressure Slab Molding
BPCTCA Effluent Limitations
Units: kg pollutant per kkg of product
or: Ib pollutant per 1,000 Ib of product
Maximum for any
One Day Period
Shall Not Exceed
Maximum Average of
Daily Values for any
Period of 30
Consecutive Days
0.0780
0.0234
0.0260
0.0078
6.0 to 9.0
Pollutant
Parameter
Suspended Solids
Oil & Grease
pH
M Hot Forming Primary
BPCTCA Effluent Limitations
Units: kg pollutant per kkg of product
or: Ib pollutant per 1,000 Ib of product
Pollutant
Parameter
1. Carbon
Maximum for any
One Day Period
Shall Not Exceed
Maximum Average of
Daily Values for any
Period of 30
Consecutive Days
(a) Rolling Operation
Suspended Solids 0.1113
Oil and Grease 0.0864
pH 6.0
to
0.0371
0.0288
9.0
(b) Hot Scarfing*
-------
Suspended Solids
Oil and Grease
pH
0.0246
0.0192
6.0
to
0.0082
0.0064
9.0
*Applies in addition to limitation stated immediately
above, if the primary hot forming operation has a hot
scarf er wet scrubber associated with the rolling operation.
2. Alloy and Stainless
Oil and Grease
Suspended Solids
pH
0.1524
0.1962
6.0 to 9.0
0.0508
0.0654
3. Mahoning Valley
The limitations set forth above in this section shall not
apply to any operation located in the Mahoning Valley which
otherwise would be subject to the provisions in this
section.
N
Hot Forming Section
BPCTCA Effluent Limitations
Units:
or:
Pollutant
Parameter
Suspended Solids
Oil and Grease
pH
kg pollutant per kkg of product
Ib pollutant per lrOOO Ib of product
Maximum for any
One Day Period
Shall Not Exceed
0.7260
0.3285
6.0
to
Maximum Average of
Daily Values for any
Period of 30
Consecutive Days
0.2420
0.1095
9.0
Mahoning Valley
The limitations set forth above in this section shall not
apply to any operation located in the Mahoning Valley which
otherwise would be subject to the provisions in this
section.
O Hot Forming Flat
BPCTCA Effluent Limitations
Units: kg pollutant per kkg of product
or: Ib pollutant per 1,000 Ib of product
-------
Maximum for any
One Day Period
Shall Not Exceed
Pollutant
Parameter
(a) Plate
1. Carbon
Suspended Solids 0.5004
Oil & Grease 0.5004
PH
2. Alloy and Stainless
Maximum Average of
Daily Values for any
Period of 30
Consecutive Days
6.0 to 9.0
Suspended Solids 1.1280
Oil and Grease 1.1280
pH 6.0 to
(b) Hot Strip and Sheet
Suspended Solids 0.9924
Oil and Grease 0.5229
pH 6.0 to
0.1668
0.1668
0.3760
0.3760
9.0
0.3308
0.1743
9.0
3. Mahoning Valley
The limitations set forth above in this section shall not
apply to any operation located in the Mahoning Valley which
otherwise would be subject to the provisions in this
section.
J? Pipe and Tubes
BPCTCA Effluent Limitations
Units: kg pollutant per kkg of product
or: Ib pollutant per 1,000 Ib of product
Pollutant
Parameter
Suspended Solids
Oil and Grease
PH
Maximum for any
One Day Period
Shall Not Exceed
0.4254
0.1254
6.0
to
Maximum Average of
Daily Values for any
Period of 30
Consecutive Days
0.1418
0.0418
9.0
Mahoning Valley
-------
The limitations set forth above in this section shall not
apply to any operation located in the Mahoning Valley which
otherwise would be subject to the provisions in this
section.
9. Pickling-Sulfuric Acid-Batch and Continuous
BPCTCA Effluent Limitations
Units: kg pollutant per kkg of product
or: Ib pollutant per 1,000 Ib of product
Maximum Average of
Maximum for any Daily Values for any
Pollutant One Day Period Period of 30
Parameter Shall Not Exceed Consecutive Days
(a) Batch pickling operations; spent pickle liquor and
rinses: There shall be no discharge of process waste
water pollutants to navigable waters.
(b) Continuous pickling operations with existing facil-
ities for neutralization of spent pickle liquor:
Suspended Solids 0.0156 0.0052
Oil and Grease* 0.00312 0.00104
Dissolved Iron 0.00033 0.00011
pH 6.0 to 9.0
* This load is allowed only when these wastes are treated
in combination with cold rolling mill wastes.
(c) Continuous pickling operations, with existing
facilities for neutralization of rinses and fume
hood scrubber effluents:
Suspended Solids 0.1407 0.0469
Oil and Grease* 0.0282 0.0094
Dissolved Iron 0.00282 0.00094
pH 6.0 to 9.0
* This load is allowed only when these wastes are treated
in combination with cold rolling mill wastes.
(d) Continuous pickling operations, other: There
shall be no discharge of process wastewater pollutants
to navigable waters.
Mahoning Valley
-------
The limitations set forth above in this section shall not
apply to any operation located in the Mahoning Valley which
otherwise would be subject to the provisions in this
section.
R Pickling-Hydrochloric Acid~Batch and Continuous
BPCTCA Effluent Limitations
Units: kg pollutant per kkg of product
or: Ib pollutant per 1,000 Ib of product
Maximum Average of
Maximum for any Daily Values for any
Pollutant One Day Period Period of 30
Parameter Shall Not Exceed Consecutive Days
(a) Concentrates from non-regenerative operations:
Suspended Solids 0.0189 0.0063
Oil and Grease * 0.0039 0.0013
Dissolved Iron 0.00039 0.00013
pH 6.0 to 9.0
* This load applies only when these wastes are treated
in combination with cold rolling mill wastes.
(b) Absorber Vent Scrubber *
Suspended Solids 0.1251 0.0417
Oil and Grease** 0.0249 0.0083
Dissolved Iron 0.00249 0.00083
pH 6.0 to 9.0
* This load applies in place of Hydrochloric Acid
Pickling-Concentrate load as indicated in (a) above
if the concentrate section has an acid regeneration unit
with an absorber vent scrubber.
** This load applies only when these wastes are treated
in combination with cold rolling mill wastes.
(c) Rinse Waters
Suspended Solids 0.1251 0.0417
Oil and Grease* 0.0249 0.0083
Dissolved Iron 0.00249 0.00083
pH 6.0 to 9.0
* This load applies only when these wastes are treated
in combination with cold rolling mill wastes.
-------
(d) Pickle Line Fume Scrubber Wastes *
Suspended Solids
Oil and Grease**
Dissolved Iron
PH
0.0312
0.0063
0.00063
6.0
to
0.0104
0.0021
0.00021
9.0
* This limitation applies in addition to Hydrochloric
Acid Pickling-RLnse effluent limitations if the pickle line
has a fume hood scrubber.
** This load applies only when these wastes are treated
in combination with cold rolling mill wastes.
Mahoning Valley
The limitations set forth above in this section shall not
apply to any operation located in the Mahoning Valley which
otherwise would be subject to the provisions in this
section.
Cold Rolling
BPCTCA Effluent Limitations
Units: kg pollutant per kkg of product
or: Ib pollutant per 1,000 Ib of product
Pollutant
Parameter
(a) Recirculation
Suspended Solids
Oil and Grease
Dissolved Iron*
PH
Maximum for any
One Day Period
Shall Not Exceed
0.0078
0.00312
0.0003
6.0
to
Maximum Average of
Daily Values for any
Period of 30
Consecutive Days
0.0026
0.00104
0.00011
9.0
* This load applies only when these wastes are treated
in combination with pickle line wastewaters.
(b) Combination
Suspended Solids
Oil and Grease
Dissolved Iron *
pH
0.1251
0.0501
0.00501
6.0
to
0.0417
0.0167
0.00167
9.0
-------
* This load applies only when these wastes are treated
in combination with pickle line wastewaters.
(c) Direct Application
Suspended Solids 0.3126
Oil and Grease 0.1251
Dissolved Iron(l) 0.0126
pH 6.0
to
0.1042
0.0417
0.0042
9.0
* This load applies only when these wastes are treated
in combination with pickle line wastewaters.
T Hot Coatings-Galvanizing
BPCTCA Effluent Limitations
Units: kg pollutant per kkg of product
or: Ib pollutant per 1,000 Ib of product
Pollutant
Parameter
(a) Rinse Waters
Suspended Solids
Oil and Grease
Total Zinc
Hexavalent Chromium
Total Chromium
pH
Maximum for any
One Day Period
Shall Not Exceed
0.3750
0.1125
0.0375
0.00015
0.0225
6.0
(b) Fume Hood Scrubber*
Suspended Solids 0.3750
Oil and Grease 0.1125
Total Zinc 0.0375
Hexavalent Chromium 0.00015
Total Chromium 0.0225
pH 6.0
Maximum Average of
Daily Values for any
Period of 30
Consecutive Days
0.1250
0.0375
0.0125
0.00005
0.0075
to 9.0
0.1250
0.0375
0.0125
0.00005
0.0075
to 9.0
* Applies in addition to the limitations stated immedi-
ately above, if the galvanizing line has a fume hood
scrubber.
U Hot Coatings-Terne
BPCTCA Effluent Limitations
10
-------
Units:
or:
Pollutant
Parameter
(a) Rinse Waters
Suspended Solids
Oil and Grease
Total Lead
Total Tin
PH
kg pollutant per kkg of product
Ib pollutant per 1,000 Ib of product
Maximum for any
One Day Period
Shall Not Exceed
0.3750
0.1125
0.00375
0.0375
6.0
to
Maximum Average of
Daily Values for any
Period of 30
Consecutive Days
0.1250
0.0375
0.00125
0.0125
9.0
(b) Fume Hood Scrubber*
Suspended Solids 0.3750
Oil and Grease 0.1125
Total Lead 0.00375
Total Tin 0.0375
pH 6.0
0.1250
0.0375
0.00125
0.0125
to 9.0
* Applies in addition to the limitations stated immedi-
ately above, if the terne line has a fume hood scrubber.
V Miscellaneous Runoffs - Storage Piles, Casting and
Slagging
(a) Discharges from Coal, Limestone and Ore Storage Piles:
No limitations are established for BPCTCA.
(b) Discharges from Casting or Slagging Operations:
There shall be no discharge of process (i.e. contact)
wastewater pollutants to navigable waters.
W. Combination Pickling Acid (Batch and Continuous)
BPCTCA Effluent Limitations
Units: kg pollutant per kkg of product
or: Ib pollutant per 1,000 Ib of product
Pollutant
Parameter
Maximum for any
One Day Period
Shall Not Exceed
Maximum Average of
Daily Values for any
Period of 30
Consecutive Days
11
-------
(a) Continuous operations:
Suspended Solids
Oil S Grease*
Dissolved Cr
Dissolved Iron
Fluoride
Dissolved Nickel
pH
0.
0,
0.
0.
0.
0.
3129
1251
0063
0126
1878
0030
0.1043
0.0417
0.0021
0.0042
0.0626
0.0010
6.0 to 9.0
* Applicable only if combined with cold rolling wastes for
treatment.
(b) Batch Pipe and Tube Operations:
Suspended Solids
Oil S Grease*
Dissolved Cr
Dissolved Iron
Fluoride
Dissolved Nickel
pH
0.2190
0.0876
0.0045
0.0087
0.1314
0.0021
0.0730
0.0292
0.0015
0.0029
0.0438
0.0007
6.0 to 9.0
* Applicable only if combined with cold rolling wastes for
treatment.
(c) Other Batch Operations:
Suspended Solids
Oil & Grease*
Dissolved Cr
Dissolved Iron
Fluoride
Dissolved Nickel
PH
0.0627
0.0249
0.0012
0.0024
0.0375
0.0006
0.0209
0.0083
0.0004
0.0008
0.0125
0.0002
6.0 to 9.0
* Applicable only if combined with cold rolling wastes for
treatment.
X. Scale Removal (Kolene and Hydride)
BPCTCA Effluent Limitations
Units: kq pollutant per kkg of product
or: Ib pollutant per 1,000 Ib of product
Pollutant
Parameter
Maximum for any
One Day Period
Shall Not Exceed
Maximum Average of
Daily Values for any
Period of 30
Consecutive Days
12
-------
(a) Kolene
Suspended Solids
Cr6
Dissolved Cr
Dissolved Iron
Cyanide
PH
(b) Hydride
Suspended Solids
Cr6
Dissolved Cr
Dissolved Iron
Cyanide
PH
0.1563
0.0003
0.0030
0.0063
0.0015
6.0 to 9.0
0.3753
0.0009
0.0075
0.0150
0.0039
0.0521
0.0001
0.0010
0.0021
0.0005
0.1251
0.0003
0.0025
0.0050
0.0013
6.0 to 9.0
Wire Coating and Pickling
BPCTCA Effluent Limitations
Units: kg pollutant per kkg of product
or: Ib pollutant per 1,000 Ib of product
Pollutant
Parameter
Suspended Solids
Oil & Grease*
Cr
Dissolved Iron
Cyanide
Fluoride
Dissolved Nickel
Dissolved Copper
PH
Maximum for any
One Day Period
Shall Not Exceed
0.3129
0.1251
0.0063
0.0126
0.0030
0. 1878
0.0030
0.0030
Maximum Average of
Daily Values for any
Period of 30
Consecutive Days
0.1043
0.0417
0.0021
0.0042
0.0010
0.0626
0.0010
0.0010
6.0 to 9.0
* Applicable only if combined with cold rolling wastes for
treatment.
Z. Continuous Alkaline Cleaning
BPCTCA Effluent Limitations
Units: kg pollutant per kkg of product
or: Ib pollutant per 1,000 Ib of product
13
-------
Pollutant
Parameter
Suspended Solids
Dissolved Cr
Dissolved Iron
Dissolved Nickel
PH
Maximum for any
One Day Period
Shall Not Exceed
0.0156
0.0003
0.0006
0.00015
Maximum Average of
Daily Values for any
Period of 30
Consecutive Days
0.0052
0.0001
0.0002
0.00005
6.0 to 9.0
PART II - BEST AVAILABLE TECHNOLOGY ECONOMICALLY ACHIEVABLE
(BATEA - 1983)
The effluent guidelines representing the effluent
limitations quality obtainable by existing point sources
through the application of the best available technology
economically achievable (BATEA) for each industry
subcategory are as follows:
G. Basic Oxygen Furnace (Wet Air Pollution Control Methods)
BATEA Effluent Limitations (1)
Units: kg pollutant per kkg of product
or: Ib pollutant per 1,000 Ib of product
Pollutant
Parameter
Suspended Solids
Fluoride
PH
Maximum for any
One Day Period
Shall Not Exceed
0.0156
0.0126
Maximum Average of
Daily Values for any
Period of 30
Consecutive Days
0.0052
0.0042
6.0 to 9.0
K. Vacuum Degassing
BATEA Effluent Limitations (1)
Units: kg pollutant per kkg of product
or: Ib pollutant per 1,000 Ib of product
Pollutant
Parameter
Su spende d So li ds
Maximum for any
One Day Period
Shall Not Exceed
0.0078
Maximum Average of
Daily Values for any
Period of 30
Consecutive Days
0.0026
14
-------
Zinc 0.0015 0.0005
Manganese 0.0015 0.0005
Lead 0.00015 0.00005
Nitrate (as NO3) 0.0141 0.0047
pH 6.0 to 9.0
L. Continuous Casting and Pressure Slab Molding
BATEA Effluent Limitations (1)
Units: kg pollutant per kkg of product
or: lb pollutant per 1,000 lb of product
Maximum Average of
Maximum for any Daily Values for any
Pollutant One Day Period Period of 30
Parameter Shall Not Exceed Consecutive Days
Suspended Solids 0.0156 0.0052
Oil & Grease 0.0156 0.0052
pH 6.0 to 9.0
M Hot Forming Primary
BATEA Effluent Limitations (1)
Units: kg pollutant per kkg of product
or: lb pollutant per 1,000 lb of product
Maximum Average of
Maximum for any Daily Values for any
Pollutant One Day Period Period of 30
Parameter Shall Not Exceed Consecutive Days
1. Carbon
(a) Rolling Operation
Suspended Solids 0.0033 0.0011
Oil and Grease 0.0033 0.0011
pH 6.0 to 9.0
(b) Hot Scarfing* included in (a)
* No additional load is allowed for hot scarfing since
scarfer scrubber water is part of the total primary mill
recycle system.
2. Alloy and Stainless
Suspended Solids 0.0051 0.0017
Oil and Grease 0.0051 0.0017
15
-------
pH 6.0 to 9.0
3. Mahoninq Valley
The limitations set forth above in this section may be
modified under the provisions of Section 301(c) of the Act;
however, for operations located in the Mahoning Valley, any
such modified limitations shall not be less stringent than
those set forth below, which limitations represent the
maximum quantity of pollutants controlled by this section
which may be discharged consistent with the requirements of
Section 301 (c) .
BATEA Effluent Limitations
Units: kg pollutant per kkg of product
or: Ib pollutant per 1,000 Ib of product
Maximum Average of
Maximum for any Daily Values for any
Pollutant One Day Period Period of 30
Parameter Shall Not Exceed Consecutive Days
TSS 0.8238 0.2746
Oil and Grease 0.5391 0.1797
pH 6.0 to 9.0
N Hot Forming Section
BATEA Effluent Limitations
Units: kg pollutant per kkg of product
or: Ib pollutant per 1,000 Ib of product
Maximum Average of
Maximum for any Daily Values for any
Pollutant One Day Period Period of 30
Parameter Shall Not Exceed Consecutive Days
Carbon and Alloy and Stainless
No discharge of process wastewater
pollutants to navigable waters.
Mahoning Valley
The limitations set forth above in this section may be
modified under the provisions of Section 301 (c) of the Act;
however, for operations located in the Mahoning Valley, any
such modified limitations shall not be less stringent than
those set forth below, which limitations represent the
maximum quantity of pollutants controlled by this section
16
-------
which may be discharged consistent with the requirements of
Section 301(c).
BATEA Effluent Limitations
Units: kg pollutant per kkg of product
or: Ib pollutant per 1,000 Ib of product
Pollutant
Parameter
TSS
Oil and Grease
pH
Maximum for any
One Day Period
Shall Not Exceed
2.2560
0.7062
6.0
Maximum Average of
Daily Values for any
Period of 30
Consecutive Days
0.7520
0.2354
to 9.0
Hot Forming Flat
BATEA Effluent Limitations
Units: kg pollutant per kkg of product
or: Ib pollutant per 1,000 Ib of product
Pollutant
Parameter
(a) Plate
1. Carbon
Suspended Solids
Oil and Grease
pH
2. Alloy and Stainless
Suspended Solids
Oil & Grease
PH
Maximum for any
One Day Period
Shall Not Exceed
Maximum Average of
Daily Values for any
Period of 30
Consecutive Days
0.0192
0.0192
6.0
0.0438
0.0438
to
0.0064
0.0064
9.0
0.0146
0.0146
6.0 to 9.0
(b) All other operations producing flat products
(Hot Strip and Sheet) :
There shall be no discharge of
process wastewater pollutants to
navigable waters.
Mahoning Valley
17
-------
The limitations set forth above in this section may be
modified under the provisions of section 301(c) of the Act;
however, for operations located in the Mahoning Valley, any
such modified limitations shall not be less stringent than
those set forth below, which limitations represent the
maximum quantity of pollutants controlled by this section
which may be discharged consistent with the requirements of
Section 30 1 (c) .
BATEA Effluent Limitations
Units: kg pollutant per kkg of product
or: Ib pollutant per 1,000 Ib of product
Pollutant
Parameter
TSS
Oil and Grease
pH
P Pipe and Tubes
Maximum for any
One Day Period
Shall Not Exceed
1.7661
0.8568
6.0
Maximum Average of
Daily Values for any
Period of 30
Consecutive Days
0.5887
0.2856
to
9.0
BATEA Effluent Limitations
Units: kg pollutant per kkg of product
or: Ib pollutant per 1,000 Ib of product
Pollutant
Parameter
Maximum for any
One Day Period
Shall Not Exceed
Maximum Average of
Daily Values for any
Period of 30
Consecutive Days
There shall be no discharge of
process wastewater pollutants to
navigable waters.
Mahoning Valley
The limitations set forth above in this section may be
modified under the provisions of Section 301(c) of the Act;
however, for operations located in the Mahoning Valley, any
such modified limitations shall not be less stringent than
those set forth below, which limitations represent the
maximum quantity of pollutants controlled by this section
which may be discharged consistent with the requirements of
Section 301 (c) .
BATEA Effluent Limitations
Units: kg pollutant per kkg of product
18
-------
or: Ib pollutant per 1,000 Ib of product
Maximum Average of
Maximum for any Daily Values for any
Pollutant One Day Period Period of 30
Parameter Shall Not Exceed Consecutive Days
TSS 4.2597 1.4199
Oil and Grease 1.0527 0.3509
pH 6.0 to 9.0
Q Pickling-Sulfuric Acid-Batch and Continuous
BATEA Effluent Limitations
Units: kg pollutant per kkg of product
or: Ib pollutant per 1,000 Ib of product
Maximum Average of
Maximum for any Daily Values for any
Pollutant One Day Period Period of 30
Parameter Shall Not Exceed Consecutive Days
(a) Batch and Continuous Pickling Operations, Spent Pickle
Liquor and Rinse:
No Discharge of Process
Wastewater Pollutants
to Navigable Waters*
* Vacuum eductor condenser water is considered noncontact
cooling water.
(b) Continuous pickling operations with existing facilities
for neutralization of pickle liquors:
Suspended Solids 0.0078 0.0026
Oil and Grease* 0.00312 0.00104
Dissolved Iron 0.000312 0.000104
pH 6.0 to 9.0
* This load applies only when these wastes are treated
in combination with cold rolling mill wastes.
(c) Continuous pickling operations with existing facil-
ities for neutralization of rinses and fume hood
scrubber effluents:
Suspended Solids 0.0078 0.0026
Oil and Grease* 0.00312 0.00104
19
-------
Dissolved Iron
PH
0.000312
6.0
to
0.000104
9.0
* This load applies only when these wastes are treated
in combination with cold rolling mill wastes.
(3) Continuous pickling operations, other
There shall be no discharge of
process wastewater pollutants to
navigable waters.
Mahoning Valley
The limitations set forth above in this section may be
modified under the provisions of Section 301(c) of the Act;
however, for operations located in the Mahoning Valley, any
such modified limitations shall not be less stringent than
those set forth below, which limitations represent the
maximum quantity of pollutants controlled by this section
which may be discharged consistent with the requirements of
Section 301 (c) .
BATEA Effluent Limitations
Units:
or:
Pollutant
Parameter
1. Rinses:
Dissolved Iron
Suspended Solids*
Oil and Grease*
pH
kg pollutant per kkg of product
Ib pollutant per 1,000 Ib of product
Maximum for any
One Day Period
Shall Not Exceed
0.0282
0.0705
0.0282
6.0
to
Maximum Average of
Daily Values for any
Period of 30
Consecutive Days
0.0094
0.0235
0.0094
9.0
2. Concentrates:
There shall be no discharge of process
wastewater pollutants to navigable waters.
3. Fume Hood Scrubbers
Dissolved Iron 0.0063
Suspended Solids* 0.0156
Oil and Grease* 0.0063
0.0021
0.0052
0.0021
20
-------
pH
*
6.0
to
9.0
NOTE: This limitation applies only when these wastes
are treated in combination with cold rolling mill
wastes (Subparts) .
Pickling-Hydrochloric Acid-Batch and Continuous
BATEA Effluent Limitations
Units: kg pollutant per kkg of product
or: Ib pollutant per 1,000 Ib of product
Pollutant
Parameter
(a) Concentrates
Suspended Solids
Oil and Grease *
Dissolved Iron
PH
Maximum for any
One Day Period
Shall Not Exceed
0.0093
0.0039
0.00039
6.0
to
Maximum Average of
Daily Values for any
Period of 30
Consecutive Days
0.0031
0.0013
0.00013
9.0
* This load applies only when these wastes are treated
in combination with cold rolling mill wastes.
(b) Absorber Vent Scrubber*
Suspended Solids
Oil and Grease**
Dissolved Iron
PH
0.0093
0.0039
0.00039
6.0
to
0.0031
0.0013
0.00013
9.0
* These limitations apply in place of Hydrochloric Acid
Pickling-Concentrate Subcategory effluent limitations if the
concentrate section has an acid regeneration unit equipped
with an absorber vent scrubber.
** This load applies only when these wastes are treated in
combination with cold rolling mill wastes.
(c) Rinse Waters
Suspended Solids
Oil and Grease*
Dissolved Iron
PH
0.0156
0.0063
0.00063
6.0
to
0.0052
0.0021
0.00021
9.0
* This load applies only when these wastes are treated
21
-------
in combination with cold rolling mill wastes.
(d) Pickle Line Fume Scrubber Wastes (*)
Suspended Solids
Oil and Grease**
Dissolved Iron
pH
0.0156
0.0063
0.00063
6.0
to
0.0052
0.0021
0.00021
9.0
* These limitations apply in addition to Hydrochloric
Acid Pickling-Rinse effluent limitations if the pickle line
has a fume hood scrubber.
** This load applies only when these wastes are treated
in combination with cold rolling mill wastes.
Mahoning Valley
The limitations set forth above in this section may be
modified under the provisions of Section 301(c) of the Act;
however, for operations located in the Mahoning Valley, any
such modified limitations shall not be less stringent than
those set forth below, which limitations represent the
maximum quantity of pollutants controlled by this section
which may be discharged consistent with the requirements of
Section 301 (c) .
BATEA Effluent Limitations
Units:
or:
Pollutant
Parameter
1. Rinses:
Dissolved Iron
Suspended Solids*
Oil and Grease*
pH
kg pollutant per kkg of product
Ib pollutant per 1,000 Ib of product
Maximum for any
One Day Period
Shall Not Exceed
0.0249
0.0627
0.0249
6.0
Maximum Average of
Daily Values for any
Period of 30
Consecutive Days
0.0083
0.0209
0.0083
to 9.0
2. Concentrates:
There shall be no discharge of process
wastewater pollutants to navigable waters.
22
-------
3. Fume Hood Scrubbers
Dissolved Iron 0.0063
Suspended Solids* 0.0156
Oil and Grease* 0.0063
pH 6.0
0.0021
0.0052
0.0021
to
9.0
NOTE: These limitations apply only when these wastes
are treated in combination with cold rolling mill
wastes (Subparts)
Cold Rolling
BATEA Effluent Limitations
Units:
or:
Pollutant
Parameter
(a) Recirculation
Suspended Solids
Oil and Grease
Dissolved Iron*
PH
kg pollutant per kkg of product
Ib pollutant per 1,000 Ib of product
Maximum for any
One Day Period
Shall Not Exceed
0.0078
0.00312
0.000312
6.0
Maximum Average of
Daily Values for any
Period of 30
Consecutive Days
0.0026
0.00104
0.000104
to 9.0
* This load applies only when these wastes are treated
in combination with pickle line wastewaters.
(b) Combination
Suspended Solids
Oil and Grease
Dissolved Iron*
PH
0.1251
0.0501
0.0051
6.0
to
0.0417
0.0167
0.0017
9.0
* This load applies only when these wastes are treated
in combination with pickle line wastewaters.
(c) Direct Application
Suspended Solids 0.3126
Oil and Grease 0.1251
Dissolved Iron* 0.0126
pH 6.0
0.1042
0.0417
0.0042
to
9.0
* This load applies only when these wastes are treated
23
-------
in combination with pickle line wastewaters.
Mahoning Valley
The limitations set forth above in this section may be
modified under the provisions of Section 301(c) of the Act;
however, for operations located in the Mahoning Valley, any
such modified limitations shall not be less stringent than
those set forth for BPT, which limitations represent the
maximum quantity of pollutants controlled by this section
which may be discharged consistent with the requirements of
Section 301 (c) .
T Hot Coatings-Galvanizing
BATEA Effluent Limitations
Units: kg pollutant per kkg of product
or: Ib pollutant per 1,000 Ib of product
Pollutant
Parameter
(a) Rinse Waters
Suspended Solids
Oil and Grease
Total Zinc
Hexavalent Chromium
Total Chromium
PH
Maximum for any
One Day Period
Shall Not Exceed
0.0312
0.0126
0.00249
0.000024
0.000252
6.0
(b) Fume Hood Scrubber*
Suspended Solids 0.0468
Oil and Grease 0.0189
Total Zinc 0.00375
Hexavalent Chromium 0.000039
Total Chromium 0.000378
pH 6.0
Maximum Average of
Daily Values for any
Period of 30
Consecutive Days
0.0104
0.0042
0.00083
0.000008
0.000084
to 9.0
0.0156
0.0063
0.00125
0.000013
0.000126
to 9.0
* Applies in addition to the limitation stated
immediately above if the galvanizing line has a fume hood
scrubber.
Mahoning Valley
The limitations set forth above in this section may be
modified under the provisions of Section 301(c) of the Act;
24
-------
however, for operations located in the Mahoning Valley, any
such modified limitations shall not be less stringent than
those set forth for BPT, which limitations represent the
maximum quantity of pollutants controlled by this section
which may be discharged consistent with the requirements of
Section 301(c) .
U Hot Coatings-Terne
BATEA Effluent Limitations
Units: kg pollutant per kkg of product
or: Ib pollutant per 1,000 Ib of product
Pollutant(l)
Parameter
(a) Rinse Waters
Maximum for any
One Day Period
Shall Not Exceed
Suspended Solids 0.0312
Oil and Grease 0.0126
Total Tin 0.00249
Total Lead 0.000312
pH 6.0
(b) Fume Hood Scrubber*
to
Suspended Solids 0.0468
Oil and Grease 0.0189
Total Tin 0.00375
Total Lead 0.000468
pH 6.0 to
Maximum Average of
Daily Values for any
Period of 30
Consecutive Days
0.0104
0.0042
0.00083
0.000104
9.0
0.0156
0.0063
0.00125
0.000156
9.0
* This limitation applies in addition to the limitation
stated immediately above if the terne line has a fume hood
scrubber.
Mahoning Valley
The limitations set forth above in this section may be
modified under the provisions of Section 301(c) of the Act;
however, for operations located in the Mahoning Valley, any
such modified limitations shall not be less stringent than
those set forth for BPT, which limitations represent the
maximum quantity of pollutants controlled by this section
which may be discharged consistent with the requirements of
Section 301(c).
25
-------
Miscellaneous Runoffs-Storage Piles, Casting and Slagging
(a) Discharges from Coal, Limestone and Ore Storage Piles:
Pollutant
Parameter
Suspended Solids
PH
Maximum for any
One Day Period
Shall Not Exceed
mg/1
75*
6.0
to
Maximum Average of
Daily Values for any
Period of 30
Consecutive Days
mg/1
25*
9.0
*This concentration applies only when the rainfall rate is
2.5 inches or less in any preceeding five day period.
(b) Discharges from Casting or Slagging Operations
There shall be no discharge of process (i.e. contact)
wastewater pollutants to navigable waters.
Mahoning Valley
The limitations set forth above in this section may be
modified under the provisions of Section 301 (c) of the Act;
however, for operations located in the Mahoning Valley, any
such modified limitations shall not be less stringent than
those set forth for BPT, which limitations represent the
maximum guantity of pollutants controlled by this section
which may be discharged consistent with the requirements of
Section 301 (c) .
W. Combination Pickling Acid (Batch and Continuous)
BATEA Effluent Limitations
Units: kg pollutant per kkg of product
or: Ib pollutant per 1,000 Ib of product
Pollutant (1)
Parameter
Maximum for any
One Day Period
Shall Not Exceed
(a) Continuous Operations:
Suspended Solids
Oil & Grease*
Dissolved Cr
Dissolved Iron
Fluoride
0,
0.
0.
0,
3129
1251
0063
0126
0.1878
Maximum Average of
Daily Values for any
Period of 30
Consecutive Days
0.1043
0.0417
0.0021
0.0042
0.0626
26
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Dissolved Nickel 0.0030 0.0010
pH 6.0 to 9.0
* Applicable only if combined with cold rolling wastes for
treatment.
(b) Batch Pipe and Tube Operations:
Suspended Solids 0.2190 0.0730
Oil & Grease* 0.0876 0.0292
Dissolved Cr 0.0045 0.0015
Dissolved Iron 0.0087 0.0029
Fluoride 0.1314 0.0438
Dissolved Nickel 0.0021 0.0007
pH 6.0 to 9.0
* Applicable only if combined with cold rolling wastes for
treatment.
(c) Other Batch Operations:
Suspended Solids 0.0627 0.0209
Oil & Grease* 0.0249 0.0083
Dissolved Cr 0.0012 0.0004
Dissolved Iron 0.0024 0.0008
Fluoride 0.0375 0.0125
Dissolved Nickel 0.0006 0.0002
pH 6.0 to 9.0
* Applicable only if combined with cold rolling wastes for
treatment.
Mahoning Valley
The limitations set forth above in this section may be
modified under the provisions of Section 301 (c) of the Act;
however, for operations located in the Mahoning Valley, any
such modified limitations shall not be less stringent than
those set forth for BPT, which limitations represent the
maximum guantity of pollutants controlled by this section
which may be discharged consistent with the requirements of
Section 301 (c) .
X. Scale Removal (Kolene and Hydride^
BATEA Effluent Limitations
Units: kg pollutant per kkg of product
or: Ib pollutant per 1,000 Ib of product
27
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Pollutant(l)
Parameter
(a) Kolene
Suspended Solids
Cr6
Dissolved Cr
Dissolved Iron
Cyanide
PH
Maximum for any
One Day Period
Shall Not Exceed
0. 1563
0.0003
0.0030
0.0063
0.0015
Maximum Average of
Daily Values for any
Period of 30
Consecutive Days
0.0521
0.0001
0.0010
0.0021
0.0005
6.0 to 9.0
(b) Hydride
Suspended Solids
Cr6
Dissolved Cr
Dissolved Iron
Cyanide
PH
Mahoning Valley
0.3753
0.0009
0.0075
0.0150
0.0039
6.0 to 9.0
0.1251
0.0003
0.0025
0.0050
0.0013
The limitations set forth above in this section may be
modified under the provisions of Section 301 (c) of the Act;
however, for operations located in the Mahoning Valley, any
such modified limitations shall not^ be less stringent than
those set forth for BPT, which limitations represent the
maximum quantity of pollutants controlled by this section
which may be discharged consistent with the requirements of
Section 301(c).
Y. Wire Coating and Pickling
BATEA Effluent Limitations
Units: kg pollutant per kkg of product
or: Ib pollutant per 1,000 Ib of product
Pollutant (1)
Parameter
Suspended Solids
Oil & Grease*
Cr
Maximum for any
One Day Period
Shall Not Exceed
0.3129
0.1251
0.0063
Maximum Average of
Daily Values for any
Period of 30
Consecutive Days
0.1043
0.0417
0.0021
28
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Dissolved Iron
Cyanide
Fluoride
Dissolved Nickel
Dissolved Copper
PH
0.0126
0.0030
0.1878
0.0030
0.0030
0.0042
0.0010
0.0626
0.0010
0.0010
6.0 to 9.0
* Applicable only if combined with cold rolling wastes for
treatment.
Mahoning Valley
The limitations set forth above in this section may be
modified under the provisions of Section 301(c) of the Act;
however, for operations located in the Mahoning Valley, any
such modified limitations shall not be less stringent than
those set forth for BPT, which limitations represent the
maximum quantity of pollutants controlled by this section
which may be discharged consistent with the requirements of
Section 301 (c) .
Z. Continuous Alkaline Cleaning
BATEA Effluent Limitations
Units: kg pollutant per kkg of product
or: Ib pollutant per 1,000 Ib of product
Pollutant(l)
Parameter
Maximum for any
One Day Period
Shall Not Exceed
Maximum Average of
Daily Values for any
Period of 30
Consecutive Days
Suspended Solids
Dissolved Cr
Dissolved Iron
Dissolved Nickel
PH
0.0156
0.0003
0.0006
0.00015
0.0052
0.0001
0.0002
0.00005
6.0 to 9.0
The effluent limitations guidelines representing the
effluent quality attainable by new sources (NSPS) through
the application of the best available demonstrated control
technology (BADCT), processes, operating methods or other
alternatives for each industry subcategory are as follows:
Mahoning Valley
The limitations set forth above in this section may be
modified under the provisions of Section 301(c) of the Act;
29
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however, for operations located in the Mahoning Valley, such
modified limitations shall not be less stringent than those
set forth for BPT, which limitations represent the maximum
quantity of pollutants controlled by this section which may
be discharged consistent with the requirements of Section
301 (c) .
PART III - NEW SOURCE PERFORMANCE STANDARDS (NSPS)
G Basic Oxygen Furnace (Wet Air Pollution
Control Methods)
NSPS Effluent Limitations
Units: kg pollutant per kkg of product
or: Ib pollutant per 1,000 Ib of product
Pollutant (1)
Parameter
Suspended Solids
Fluoride
pH
Maximum for any
One Day Period
Shall Not Exceed
0.0156
0.0126
Maximum Average of
Daily Values for any
Period of 30
Consecutive Days
0.0052
0.0042
6.0 to 9.0
K Vacuum Degassing
NSPS Effluent Limitations
Units:
or:
Pollutant (1)
Parameter
Suspended Solids
Zinc
Manganese
Lead
pH
kg pollutant per kkg of product
Ib pollutant per 1,000 Ib of product
Maximum for any
One Day Period
Shall Not Exceed
0.0078
0.0015
0.0015
0.00015
Maximum Average of
Daily Values for any
Period of 30
Consecutive Days
0.0026
0.0005
0.0005
0.00005
6.0 to 9.0
30
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L Continuous Casting
NSPS Effluent Limitations
Units: kg pollutant per kkg of product
or: Ib pollutant per 1,000 Ib of product
Maximum Average of
Maximum for any Daily Values for any
Pollutant(l) One Day Period Period of 30
Parameter Shall Not Exceed Consecutive Days
Suspended Solids 0.0156 0.0052
Oil & Grease 0.0156 0.0052
pH 6.0 to 9.0
M Hot Forming Primary
NSPS Effluent Limitations
Units: kg pollutant per kkg of product
or: Ib pollutant per 1,000 Ib of product
Maximum Average of
Maximum for any Daily Values for any
Pollutant One Day Period Period of 30
Parameter Shall Not Exceed (1) Consecutive Days (1)
1. Carbon
(a) Rolling Operation
Suspended Solids 0.0013 0.00043
Oil and Grease 0.0013 0.00043
pH 6.0 to 9.0
(b) Hot Scarfing* included in (a)
* No additional load applies for hot scarfing for NSPS,
since scarfer scrubber water is intended to be part of the
total primary mill recycle system.
2. Alloy and Stainless
Suspended Solids 0.0027 0.0009
Oil and Grease 0.0027 0.0009
pH 6.0 to 9.0
N Hot Forming Section
NSPS Effluent Limitations
31
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Units: kg pollutant per kkg of product
or: Ib pollutant per 1,000 Ib of product
Pollutant
Parameter
Maximum for any
One Day Period
Shall Not Exceed
Maximum Average of
Daily Values for any
Period of 30
Consecutive Days
No Discharge of Process
Wastewater Pollutants
to Navigable Waters
O Hot Forming Flat
NSPS Effluent Limitations
Units: kg pollutant per kkg of product
or: Ib pollutant per 1,000 Ib of product
Pollutant
Parameter
(a) Plate
1. Carbon
Suspended Solids
Oil and Grease
PH
2. Alloy and Stainless
Suspended Solids
Oil & Grease
PH
Maximum for any
One Day Period
Shall Not Exceed
Maximum Average of
Daily Values for any
Period of 30
Consecutive Days
0.0192
0.0192
6.0
0.0438
0.0438
to
0.0064
0.0064
9.0
0.0146
0.0146
6.0 to 9.0
(b) All other operations producing flat products
(Hot Strip and sheet) :
There shall be no discharge of
process wastewater pollutants to
navigable waters.
p Pipe and Tubes
NSPS Effluent Limitations
Units: kg pollutant per kkg of product
or: Ib pollutant per 1,000 Ib of product
32
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Maximum Average of
Maximum for any Daily Values for any
Pollutant One Day Period Period of 30
Parameter Shall Not Exceed Consecutive Days
No Discharge of Process
Wastewater Pollutants
to Navigable Waters
Q. Pickling-Sulfuric Acid-Batch and Continuous
NSPS Effluent Limitations
Units: kg pollutant per kkg of product
or: Ib pollutant per 1,000 Ib of product
Maximum Average of
Maximum for any Daily Values for any
Pollutant One Day Period Period of 30
Parameter Shall Not Exceed Consecutive Days
No Discharge of Process
Wastewater Pollutants
to Navigable Waters*
* Vacuum eductor condenser water is considered noncontact
cooling water.
R Pickling-Hydrochloric Acid-Batch and Continuous
NSPS Effluent Limitations
Units: kg pollutant per kkg of product
or: Ib pollutant per 1,000 Ib of product
Maximum Average of
Maximum for any Daily Values for any
Pollutant One Day Period Period of 30
Parameter Shall Not Exceed Consecutive Days
(a) Concentrates
Suspended Solids 0.0093 0.0031
Oil and Grease* 0.0039 0.0013
Dissolved Iron 0.00039 0.00013
pH 6.0 to 9.0
* This load is allowed only when these wastes are treated
in combination with cold rolling mill wastes.
33
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(b) Absorber Vent Scrubber *
Suspended Solids
Oil and Grease**
Dissolved Iron
PH
0.0624
0.0249
0.00249
6.0
to
0.0208
0.0083
0.00083
9.0
* These limitations apply in place of Hydrochloric
Acid Pickling-concentrate Subcategory effluent limitations
if the concentrate section has an acid regeneration unit
equipped with an absorber vent scrubber.
** This load applies only when these wastes are treated
in combination with cold rolling mill wastes.
(c) Rinse Waters
Suspended Solids
Oil and Grease*
Dissolved Iron
PH
0.0156
0.0063
0.00063
6.0
to
0.0052
0.0021
0.00021
9.0
* This load applies only when these wastes are treated
in combination with cold rolling mill wastes.
(d) Pickle Line Fume Scrubber Wastes
Suspended Solids
Oil and Grease*
Dissolved Iron
PH
0.0156
0.0063
0.00063
6.0
to
0.0052
0.0021
0.00021
9.0
* This load applies only when these wastes are treated
in combination with cold rolling mill wastes.
S Cold Rolling
NSPS Effluent Limitations
Units: kg pollutant per kkg of product
or: Ib pollutant per 1,000 Ib of product
Pollutant
Parameter
(a) Re circulation
Suspended Solids
Oil and Grease
Maximum for any
One Day Period
Shall Not Exceed
0.0078
0.00312
Maximum Average of
Daily Values for any
Period of 30
Consecutive Days
0.0026
0.00104
34
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Iron
PH
0.000312
6.0 to 9.0
0.000104
* This load applies only when these wastes are treated
in combination with pickle line wastewaters.
' (b) Combination
Suspended Solids
Oil and Grease
Dissolved Iron*
PH
0.1251
0.0501
0.0051
6.0
to
0.0417
'0.0167
0.0017
9.0
* This load applies only when these wastes are treated
in combination with pickle line wastewaters.
(c) Direct Application
Suspended Solids 0.3126
Oil and Grease 0.1251
Dissolved Iron* 0.0126
pH 6.0
to
0.1042
0.0417
0.0042
9.0
* This load applies only when these wastes are treated
in combination with pickle line wastewaters.
Hot Coatings-Galvanizing
NSPS Effluent Limitations
Units: kg pollutant per kkg of product
or: Ib pollutant per 1,000 Ib of product
Pollutant
Parameter
(a) Rinse Waters
Suspended solids
Oil and Grease
Total Zinc
Hexavalent Chromium
Total Chromium
pH
(b) Fume Hood Scrubber
Suspended solids
Maximum for any
One Day Period
Shall Not Exceed
0.1875
0.0750
0.0150
0.00015
0.00150
6.0
0.1875
Maximum Average of
Daily Values for any
Period of 30
Consecutive Days
0.0625
0.0250
0.0050
0.00005
0.00050
to 9.0
0.0625
35
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Oil and Grease
Total Zinc
Hexavalent Chromium
Total Chromium
pH
0.0750
0.0150
0.00015
0.00150
6.0
to
0.0250
0.0050
0.00005
0.00050
9.0
U Hot Coatings-Terne
NSPS Effluent Limitations
Units: kg pollutant per kkg of product
or: Ib pollutant per 1,000 Ib of product
Pollutant
Parameter
(a) Rinse Waters
Suspended Solids
Oil and Grease
Total Tin
Total Lead
PH
Maximum for any
One Day Period
Shall Not Exceed
0.1875
0.0750
0.0150
0.00189
6.0
(b) Fume Hood Scrubber
Suspended Solids 0.1875
Oil and Grease 0.0750
Total Tin 0.0150
Total Lead 0.00189
pH 6.0
Maximum Average of
Daily Values for any
Period of 30
Consecutive Days
0.0625
0.0250
0.0050
0.00063
to 9.0
0.0625
0.0250
0.0050
0.00063
to 9.0
V Miscellaneous Runoffs-Storage Piles, Casting and Slagging
(a) Discharges from Coal, Limestone and Ore Storage Piles
Pollutant
Parameter
Suspended solids
pH
Maximum for any
One Day Period
Shall NOt Exceed
mg/1
75*
6.0
to
Maximum Average of
Daily Values for any
Period of 30
Consecutive Days
mg/1
25*
9.0
*This concentration applies only when the rainfall rate is
2.5 inches or less in any preceeding five day period.
36
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(b) Discharges from Casting or Slagging Operations
There shall be no discharge of process (i.e. contact)
wastewater pollutants to navigable waters.
W. Combination Pickling Acid (Batch and Continuous)
NSPS Effluent Limitations
Units: kg pollutant per kkg of product
or: Ib pollutant per 1,000 Ib of product
Pollutant(l)
Parameter
Maximum for any
One Day Period
Shall Not Exceed
(a) Continuous Operations:
Suspended Solids
Oil 5 Grease*
Dissolved Cr
Dissolved Iron
Fluoride
Dissolved Nickel
PH
0.3129
0.1251
0.0063
0.0126
0.1878
0.0030
Maximum Average of
Daily Values for any
Period of 30
Consecutive Days
0.1043
0.0417
0.0021
0.0042
0.0626
0.0010
6.0 to 9.0
* Applicable only if combined with cold rolling wastes for
treatment.
(b) Batch Pipe and Tube
Suspended Solids 0.2190
Oil & Grease* 0.0876
Dissolved Cr 0.0045
Dissolved Iron 0.0087
Fluoride 0.1314
Dissolved Nickel 0.0021
PH
0.0730
0.0292
0.0015
0.0029
0.0438
0.0007
6.0 to 9.0
* Applicable only if combined with cold rolling wastes for
treatment.
(c) Other Batch
Suspended Solids
Oil & Grease*
Dissolved Cr
Dissolved Iron
Fluoride
Dissolved Nickel
0.0627
0.0249
0.0012
0.0024
0.0375
0.0006
0.0209
0.0083
0.0004
0.0008
0.0125
0.0002
37
-------
PH
6.0 to 9.0
* Applicable only if combined with cold rolling wastes for
treatment.
X. Scale Removal (Kolene and Hydride)
NSPS Effluent Limitations
Units: kg pollutant per kkg of product
or: Ib pollutant per 1,000 Ib of product
Pollutant (1)
Parameter
(a) Kolene
Suspended Solids
Cr6
Dissolved Cr
Dissolved Iron
Cyanide
pH
Maximum for any
One Day Period
Shall Not Exceed
0.1563
0.0003
0.0030
0.0063
0.0015
Maximum Average of
Daily Values for any
Period of 30
Consecutive Days
0.0521
0.0001
0.0010
0.0021
0.0005
6.0 to 9.0
* Applicable only if combined with other wastes for
treatment.
(b) Hydride
Suspended Solids
Cr6
Dissolved Cr
Dissolved Iron
Cyanide
PH
0.3753
0.0009
0.0075
0.0150
0.0039
0.1251
0.0003
0.0025
0.0050
0.0013
6.0 to 9.0
Y. Wire Coating and Pickling
NSPS Effluent Limitations
Units: kg pollutant per kkg of product
or: Ib pollutant per 1,000 Ib of product
Pollutant(l)
Parameter
Maximum for any
One Day Period
Shall Not Exceed
Maximum Average of
Daily Values for any
Period of 30
Consecutive Days
38
-------
Suspended Solids
Oil S Grease*
cr
Dissolved Iron
Cyanide
Fluoride
Dissolved Nickel
Dissolved Copper
PH
0.3129
0.1251
0.0063
0.0126
0.0030
0.1878
0.0030
0.0030
6.0 to 9.0
0.1043
0.0417
0.0021
0.0042
0.0010
0.0626
0.0010
0.0010
* Applicable only if combined with cold rolling wastes for
treatment.
Z. Continuous Alkaline Cleaning
NSPS Effluent Limitations
Units: kg pollutant per kkg of product
or: Ib pollutant per 1,000 Ib of product
Pollutant (1)
Parameter
Maximum for any
One Day Period
Shall Not Exceed
Maximum Average of
Daily Values for any
Period of 30
Consecutive Days
Suspended Solids
Dissolved Cr
Dissolved Iron
Dissolved Nickel
pH
0.0156
0.0003
0.0006
0.00015
0.0052
0.0001
0.0002
0.00005
6.0 to 9.0
39
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SECTION III
INTRODUCTION
Purpose and Authority
Section 301(b) of the Act requires the achievement by not
later than July 1, 1977, of effluent limitations for point
sources, other than publicly owned treatment works, which
are based on the application of the best practicable control
technology currently available as defined by the
Administrator pursuant to Section 304 (b) of the Act.
Section 301 (b) also requires the achievement by not later
than July 1, 1983, of effluent limitations for point
sources, other than publicly owned treatment works, which
are based on the application of the best available
technology economically achievable which will result in
reasonable further progress toward the national goal of
eliminating the discharge of all pollutants, as determined
in accordance with regulations issued by the Administrator
pursuant to Section 304(b) to the Act. Section 306 of the
Act requires the achievement by new sources of a Federal
standard of performance providing for the control of the
discharge of pollutants which reflects the greatest degree
of effluent reduction which the Administrator determines to
be achievable through the application of the best available
demonstrated control technology, processes, operating
methods, or other alternatives, including, where
practicable, a standard permitting no discharge of
pollutants.
Section 304(b) of the Act requires the Administrator to
publish within one year of enactment of the Act, regulations
providing guidelines for effluent limitations setting forth
the degree of practicable control technology currently
available and the degree of effluent reduction attainable
through the application of the best control measures and
practices achievable including treatment techniques, process
and procedure innovations, operation methods and other
alternatives.
Section 306 of the Act requires the Administrator, within
one year after a category of sources is included in a list
published pursuant to Section 306 (b) (1) (A) of the Act, to
propose regulations establishing Federal standards of
performance for new sources within such categories. The
Administrator published in the Federal Register of January
16, 1973, a list of 27 source categories. Publication of
the list constituted announcement of the Administrator's
-------
intention of establishing, under Section 306, standards of
performance applicable to new sources within the iron and
steel industry which was included within the list published
January 16, 1973.
Summary of Methods Used for Development of the Effluent
Limitations Guidelines and Standards of Performance
The effluent limitations guidelines and standards of
performance herein were developed in the following manner.
The point source category was first studied for the purpose
of determining whether separate limitations and standards
would be required for different segments within a point
source category. The analysis was based upon raw material
used, product produced, manufacturing process employed, and
other factors. The raw waste characteristics for each
subcategory were then identified. This included an analysis
of (1) the source and volume of water used in the process
employed and the sources of waste and wastewaters in the
plant; and (2) the constituents (including thermal) of all
wastewaters including toxic constituents and other
constituents which result in taste, odor, and color in
water. The constituents of wastewaters which should be
subject to effluent limitations guidelines and standards of
performance were identified.
The full range of control and treatment technologies
existing within each subcategory was identified. This
included an identification of each distinct control and
treatment technology, including both inplant and end-of-
process technologies, which are existent or capable of being
designed for each subcategory. It also included an
identification in terms of the amount of constituents and
the chemical, physical, and biological characteristics of
pollutants, of the effluent level resulting from the
application of each of the treatment and control
technologies. The problems, limitations and reliability of
each treatment and control technology and the required
implementation time was also identified. In addition, the
nonwater quality environmental impact, such as the effects
.of the application of such technologies upon other pollution
problems, including air, solid waste, noise and radiation
were also identified. The energy requirements of each of
the control and treatment technologies were identified as
well as the cost of the application of such technologies.
The information, as outlined above, was then evaluated in
order to determine what levels of technology constituted the
"best practicable control technology currently available,"
42
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"best available technology economically achievable" and the
"best available demonstrated control technology, processes,
operating methods, or other alternatives." In identifying
such technologies, various factors were considered. These
included the total cost of application of technology in
relation to the effluent reduction benefits to be achieved
from such application, the age of equipment and facilities
involved, the process employed, the engineering aspects of
the application of various types of control techniques,
process changes, nonwater quality environmental impact
(including energy requirements) and other factors.
The data for identification and analyses were derived from a
number of sources. These sources included EPA research
information, EPA and State environmental personnel, trade
associations, published literature, qualified technical
consultation, and on-site visits including sampling programs
and interviews at steel plants throughout the United States
which were known to have representative product lines and
production processes coincident with above average waste
treatment or control facilities. All references used in
developing the guidelines for effluent limitations and
standards of performance for new sources reported herein are
listed in Section XIII of this document. Although an
extensive literature search was conducted, the information
was generally useful only for information on broad
characterizations, trends and descriptions.
Operating plants were visited and information and samples
were collected from as many as seven mills in each of the
subcategories. These plants incorporated some 45 individual
mills covered by the study which comprised in excess of 10
percent of the United States production for the various
steel products. Both in-process and end-of-pipe data were
obtained during the actual survey. Data on raw wastewater
and effluent characteristics, water use and cost information
supplied by individual plants from plant records was also
obtained. The permit application data was of limited value
for the purposes of this study since most of this data is on
outfalls serving more than one operation and frequently was
deficient in one or more of the components needed to
correlate the data.
The reviews and analyses of data described above were
performed using accepted methodology. The "survey" data
base (45 total mills) served as the principal source of
information for all analyses. Field verification sampling
data was used principally in support of the derivation of
effluent limitations. Subjective information (plant
practices, processes, equipment, etc.) gained from the site
43
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visits was also used to complement industry submissions.
Because of the apparently representative nature of the
industry survey information, these data were used for
analyses to categorize and characterize the industry
processes, waste water discharges, and operating conditions.
The analyses involved both rigorous mathematical procedures,
(using computer statistical methods) and subjective
judgments and observations using experience from site
visits, consultant comments, information from trade
publications, and similar sources as more fully described in
Sections IV and V. Similarly, cost information was
developed on the basis of data supplied by plants in the
industry with supporting information as developed for other
segments of the iron and steel industry.
The effluent limitations and standards of performance were
derived from available data on the actual performance of
existing plants. Limitations for 1977 (BPCTCA) were derived
as the average of the performance for the best plants.
(Some data were excluded due to plant malfunctions, etc., as
noted in Section IX). The limitations for 1983 and the new
source performance standards were derived on the basis of
the very best performance achieved by a plant(s) in each
industry subcategory (between 1 and 3 plants depending upon
the availability of data for all limited parameters).
Selection of Candidate Plants for Visits
A survey of existing treatment facilities and their
performance was undertaken to develop a list of best plants
for consideration for plant visits. Information was
obtained from:
a. Study Contractors1 Personnel
b. State Environmental Agencies
c. EPA Personnel
d. Personal Contact
e. Literature Search
f. Industry Sources
g. Permit Applications
h. Permits
Since the steel industry is primarily situated in 15 states,
greatest contribution was obtained from state and EPA
personnel located in the following states: (a.) Alabama,
(b.) California, (c.) Colorado, (d.) Illinois, (e.) Indiana,
(f.) Kentucky, (g.) Maryland, (h.) Michigan, (i.) Missouri,
(j.) New York, (k.) Ohio, (1.) Pennsylvania, (m.) Texas,
(n.) Utah, and (o.) West Virginia.
44
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Personal experiences and contacts provided information
required to assess plant processes and treatment technology.
Upon completion of this plant survey, the findings were
compiled and preliminary candidate lists were prepared on
those plants that were considered by more than one source to
be providing the best or better waste treatment. These
lists were submitted to the EPA by the study contractor for
concurrence on sites to be visited. The rationale for plant
selections in all the subcategories is presented in Table 7.
In several instances, last minute substitutions had to be,
made because of the non-availability of the plant. In
several other instances, while at the plant an additional
subcategory was sampled to provide a complete study of
several systems that were tied together, i.e., cold rolling
pickling; coating - pickling. Table 8 presents a summary
of the requirements for the study.
General Description of the Industry
Although the making of steel appears to be simple, in
reality many complex activities are encountered when a great
quantity of raw materials and resources are brought together
to ultimately produce steel. Steel mills may range from
comparatively small plants to completely integrated steel
complexes. Even the smallest of plants will generally
represent a fair sized industrial complex. Because of the
wide product range, the operations will vary with each
facility.
It was not until the mid-fifties that the industry began to
look at iron and steelmaking as unit operations that
required a better knowledge of the kinetics of competing
reactions. Since this initial change in thinking, the
adoption of advanced technology has become a way of life for
the steel industry.
Approximately 92% of the 1972 total United States annual
steel ingot production was produced by 15 major steel
corporations. This total also represents 22. 5X of the world
total of 566,875,000 metric tons (625,000,000 ingot tons).
Table 1 presents the breakdown by corporation. The year of
record for steel ingot production was 1969 with 127,887,000
kkg (141,000,000 ingot tons) being produced. Table 2
presents the breakdown of alloy and stainless steel plants
for 1972.
45
-------
TABLE 1
United States Annual Steel Ingot Ton Production
Major Producers
1972
Metric Tons/Year Ingot Tons/Year
United .States Steel
Bethlehem Steel
Republic Steel
National Steel
Armco Steel
Jones & Laughlin Steel
Inland Steel
Youngstown Sheet & Tube
Wheeling Pittsburgh
Kaiser
McLouth
Colorado Fuel & Iron
Sharon
Interlake
Alan Wood
31,750,000
19,960,000
9,980,000
9,520,000
7,710,000
7,280,000
6,800,000
5,440,000
3,540,000
2,720,000
1,819,000
1,360,000
1,360,000
907,000
907,000
35,000,000
22,000,000
11,000,000
10,500,000
8,500,000
8,000,000
7,500,000
6,000,000
3,900,000
3,000,000
2,000,000
1,500,000
1,500,000
1,000,000
1,000,000
46
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Product Classification
The U. S. Bureau of Census, Census of Manufacturers,
classifies the steel industry under Major Group 33 - Primary
Metal Industries. This phase of study covers the forming,
finishing and specialty steel segments of SIC Industry No.
3312, 3315, 3316, and 3317. This includes all processes,
subprocesses, and alternate processes involved in the
manufacture of intermediate or finished products in the
above categories. A detailed list of product codes within
the industry classification code 3312, 3315, 3316, and 3317
is included in Tables 3, 4, 5, and 6, respectively. Product
classification by subcategory is presented on Table 199.
ALLOY AND STAINLESS STEEL
By common custom steel is considered to be alloy steel when
the maximum range given for the content of alloying elements
exceeds one, or more, of the following limits:
Manganese 1.65 percent
Silicon 0.60 percent
Copper 0.60 percent
Or in which a definite range or definite minimum quantity of
any of the following elements is specified or required
within the limits of the recognized field of constructional
alloy steels:
Chromium up to 3.99 percent, aluminum, cobalt, columbium,
molybdenum, nickel, titanium, tungsten, vanadium, zirconium,
or any other alloying element added to obtain a desired
alloying effect. Steels containing U.OO, or more percent of
chromium are included by convention among the special types
of alloy steels known as 'stainless and heat resisting
steels'.
Within the general field of alloy steels, the alloys known
as "stainless steels" represent a special class. They are
more resistant to rusting and staining than are the plain
carbon or low-alloy steels. The corrosion resistance of
"stainless" is primarily a function of the chromium content.
Other elements, such as copper, aluminum, silicon, nickel
and molybdenum may also increase corrosion resistance but
have limited use. The American Iron and Steel Institute has
chosen 4 percent chromium as the dividing line between
"alloy" and "stainless" steel.
Chromium has two pronounced characteristics which control
the procedures used in the alloying process. These are: (1)
49
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51
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TABLE 4
PRODUCT CLASSIFICATION BY SIC CODE (3315)
FOR THE IRON AND STEEL INDUSTRY
STEEL WIRE DRAWING AND STEEL NAILS AND SPIKES
Establishments primarily engaged in drawing wire from pur-
chased iron or steel rods, bars, or wire and which may be
engaged in the further manufacture of products made from wire;
establishments primarily engaged in manufacturing steel nails
and spikes from purchased materials are also included in this
industry. Rolling mills engaged in the production of ferrous
wire from wire rods or hot rolled bars produced in the same
establishment are classified in Industry 3312. Establishments
primarily engaged in drawing nonferrous wire are classified in
Group 335.
Brads, steel: wire or cut
Cable, steel: insulated or
armored
Horseshoe nails
Nails, steel: wire or cut
Spikes, steel: wire or cut
Staples, steel: wire or cut
Tacks, steel: wire or cut
Wire, ferrous
Wire products, ferrous:
made in wire drawing plants
Wire, steel: insulated or
armored
52
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TABLE 5
PRODUCT CLASSIFICATION BY SIC CODE (3316)
FOR THE IRON AND STEEL INDUSTRY
COLD ROLLED STEEL SHEET, STRIP, AND BARS
Establishments primarily engaged in (1) cold rolling steel
sheets and strip from purchased hot rolled sheets; (2) cold
drawing steel bars and steel shapes from purchased hot rolled
steel bars; and (3) producing other cold finished steel.
Establishments primarily engaged in the production of steel,
including hot rolled steel sheets, and further cold rolling
such sheets are classified in Industry 3312.
Cold finished steel bars
Cold rolled steel strip,
sheet, and bars: not made
in hot rolling mills
Corrugated iron and steel,
cold rolled
Flat bright steel strip,
cold rolled: not made in
hot rolling mills
Razor blade strip steel,
cold rolled: not made in
hot rolling mills
Sheet steel, cold rolled:
not made in hot rolling
mills
Wire, flat: cold rolled
strip
53
-------
TABLE
PRODUCT CLASSIFICATION BY SIC CODE (3317)
FOR THE IRON AND STEEL INDUSTRY
STEEL PIPES AND TUBES
Establishments primarily engaged in the production of welded
or seamless steel pipe and tubes and heavy riveted steel pipe
from purchased materials. Establishments primarily engaged
in the production of steel, including steel skelp or steel
blanks, tube rounds, or pierced billets, are classified in
Industry 3312.
Boiler tubes, wrought:
welded, lock joint, and
heavy riveted - not made
in rolling mills
Conduit: welded, lock joint,
and heavy riveted - not made
in rolling mills
t
Pipe, seamless steel: not
made in rolling mills
Pipe, wrought: welded, lock
joint, and heavy riveted -
not made in rolling mills
Tubes, seamless steel: not
made in rolling mills
Tubing, mechanical and
hypodermic sizes: not made
in rolling mills
Well casing, wrought:
welded, lock joint, and
heavy riveted - not made
in rolling mills
Wrought pipe and tubes:
welded, lock joint, and
heavy riveted - not made
in rolling mills
54
-------
TABLE 7
Rationale for Plant Selections
Hot Forming
PRODUCTION
FACILITIES
Blooming
Billets
Bar
Rod
C-2
Blooming
Billet
Rod
Blooming
Slabbing
Billet
Bar
Structural
Plate
Sheet
F-2
Blooming &
Slabbing
Billets
Bar
Hot strip
N-2
_
WASTEWATER TREATMENT
scale pit
scale pit
scale pit
scale pit
scale pit
scale pit
scale pit
scale pit
scale pit
scale pit
scale pit
scale pit
scale pit
scale pit
scale pit
scale pit
scale pit
scale pit
_
BASIS FOR SELECTION
The use of rapid rate
mixed media polishing
filters following some
of the secondary hot
rolling scale pits.
The use of rapid rate
mixed media polishing
filters following some
of the secondary hot
rolling scale pits.
Use of rapid rate
polishing filters
following some of the
secondary hot rolling
scale pits.
The use of rapid rate
mixed media polishing
filters following some
of the secondary hot
rolling scale pits.
The use of rapid rate
mixed media polishing
filters following some
of the secondary hot
rolling scale pits.
55
-------
TABLE 7
Hot Forming
PRODUCTION
FACILITIES
Blooming
Slabbing
Billet
Bar
Strip-sheet-
plate
Strip-sheet
plate
K-2
Slabbing
Billets
Bar
Plate
Rail
Hot strip
J-2
Blooming
Slabbing
Billet
Bar
Structural
A- 2
Blooming
Slabs
Billot &
Sheet Bar
Rod & Bar
Plate
Hot strip
WASTEWATER TREATMENT
scale pit
scale pit
scale pit
scale pit
scale pit
scale pit
scale pit
scale pit
scale pit
scale pit
scale pit
scale pit
scale pit
scale pit
scale pit
scale pit
scale pit
scale pit
scale pit
scale pit
scale pit
scnle pit
scale pit
BASIS FOR SELECTION
The use of rapid rate
mixed media polishing
filters following some
of the secondary hot
rolling scale pits.
The use of rapid rate
mixed media polishing
filters following some
of the secondary hot
rolling scale pits.
The use of rapid rate
mixed media polishing
filters following some
of the secondary hot
rolling scale pits.
The use of rapid rate
mixed media polishing
filters following some
of the secondary hot ,
rolling scale pits.
The use of rapid rate
mixed media polishing
filters following some
of the secondary hot
rolling scale pits.
56
-------
TABLE 7
Hot Forming
PRODUCTION
FACILITIES
WASTEWATER TREATMENT
BASIS FOR SELECTION
Merchant
Rod
G-2
scale pit
scale pit
The use of rapid rate
mixed media polishing
filters following some
of the secondary hot
rolling scale pits.
Blooms &
billets
Bars-plate
D-2
scale pit
scale pit
The use of rapid rate
mixed media polishing
filters following some
of the secondary hot
rolling scale pits.
57
-------
TABLE 7
Pipe Making
PRODUCTION
FACILITIES
WASTEWATER TREATMENT
BASIS FOR SELECTION
Continuous
butt weld
mill
II-2
Vacuum filter - 125 gpm
soluble oil and water"
system - oil skimming
Reported as good system
by vendor
Seamless
tube mill
E-2
Oil skimming, clarifica-
tion, pressure sand
filtration high recycle,
lagooning of blowdown.
Reported as good system
in magazine article
Continuous
butt weld
mill
.1,1-2
Reported as good system
by steel industry
representative
Electriweld
pipe
fif;- 2
Central wastewater treat-
ment system.
Reported as good system
in magazine article
Electriweld
pipe
KK-2
Central wastewater treat-
ment system.
Reported as good system
by steel industry repre-
sentative
Electriweld
& spiralweld
pipe mills
HH-2
Reported as good system
in literature reference.
58
-------
TABLE 7
Pickling
PRODUCTION
FACILITIES
WASTEWATER TREATMENT
BASIS FOR SELECTION
Wire Mill
Q-2
Batch type - H-SO. acid
regeneration
Zero discharge of pro-
cess wastewater pollu-
tants.
Strip Mill
T-2
Continuous type - H_SO.
acid regeneration
Zero discharge of process
wastewater pollutants.
Wire Mill
0-2
Batch type - H SO. acid
regeneration
Zero discharge of process
wastewater pollutants.
Wire Mill
Batch type - H.SO. acid
regeneration
Zero discharge of process
wastewater pollutants.
Bars, shapes,
tubing
P-2
Batch type - H-SO. acid
regeneration
Vacuum crystallization
utilized for cooling and
producing heptahydrate.
Oxide removal by non
acid technique.
Strip Mill
ontinuous type - H_SO.
acid regeneration
Utilizes combination
shot blasting and pickl-
ing for oxide removal.
Continuous
strip
Y-2
Acid regeneration -
HC1 - Woodall - Duckham
(Spray roaster)
Process has been in use
for several years.
59
-------
TABLE 7
Pickling
PRODUCTION
FACILITIES
WASTEWATER TREATMENT
BASIS FOR SELECTION
Continuous
strip
W-2
Acid regeneration HC1
Lurgi (fluid bed)
Process has been in use
for several years.
Continuous
strip
Acid regeneration - HC1
Woodall - Duckham (spray
roaster)
Process has been in use
for several years.
Continuous
strip
X-2
Acid regeneration - HCl
Woodall - Duckham (spray
roaster)
New system - start up
mid 1973.
Continuous
strip
Acid regeneration - HCl
Lurgi - (fluid bed)
New system - start up
late 1973 - or ear,ly
1974.
Continuous
Strip
BB-2
Continuous type - HCl
acid - lime neutralizatior
of rinse water
Reported as good by
steel industry repre-
sentatives
Continuous
wire pick-
ling batch
rod pickling
Rinses to central treat-
ment lagoon
Reported as good by
Vendor
Batch pick-
ling tubes
R-2
Lime slurry treatment of
rinse waters
Reported as good by
literature reference
60
-------
TABLE 7
Pickling
PRODUCTION
FACILITIES
WASTEWATER TREATMENT
BASIS FOR SELECTION
Batch HC1
wire picklin
V-2
Recommended by equipment
vendor
Batch HC1
wire picklin
U-2
Recommended by equipment
vendor
61
-------
TABLE 7
Cold Rolling
PRODUCTION
FACILITIES
WASTEWATER TREATMENT
BASIS FOR SELECTION
5-stand
tandem cold
mill. Cold
rolled
sheet and
tin plate.
FF-2
4 - flat bed filters
6000 gpm coolant system,
recirculating water, re-
circulating detergent,
and waste treatment
reservoirs.
Reported as good by stee
industry representative
5-stand
tandem cold
mill. Cold
rolled
sheet.
1 - flat bed filter
1500 gom detergent
solution system.
Reported as good by
vendor
5-stand
tandem cold
rolled
sheet and•
tin plate.
DD-2
2 - flat bed filters
6000 gpm oil and water
coolant system.
1 - special skimmer for
direct application oil.
Reported as good by
vendor
5-stand
tandem -
tin plate
and cold
rolled
sheet.
2 stand
temper.
1 - 5500 gpm solution
system.
1 - 1500 gpm detergent
recirculating system.
1 - 25000 gallon waste
treatment system.
1 - tramp oil skimmer.
4 - flat bed filters.
Reported as good by
vendor
3 - stand
tandem cold
rolled
sheets.
XX-2
3500 gpm soluble oil and
water system.
1 - tramp oil skimmer.
1 - flat bed filter.
Reported as good by
vendor
3 - stand
tandem tin
plate and
cold rolled
steel.
2 - flat bed filters
3000 gpm-combination
direct application and
solution system.
Reported as good by
vendor
2 - stand
tandem tin
plate.
W-2
1 - 1000 gpm solution
system.
1 - 1500 gpm solution
system.
1 - tramp oil skimmer.
2 - flat bed filters.
Reported as good by
vendor
62
-------
TABLE 7
Cold Rolling
PRODUCTION
FACILITIES
WASTEWATER TREATMENT
BASIS FOR SELECTIO::
5-stand
tandem cold
rolled steel
2-stand
tandem tin
plate.
EE-2
4 - flat bed filters
9600 gpm solution system.
3000 gpm solution system
1 - flat bed filter.
Reported as good by
steel industry
representative
6-stand
tandem tin
plate
4 - flat bed filters
12000 gpm solution system.
Reported as good by
vendor
5-stand
tandem cold
rolled
steel.
X-2
2 flat bed filters
6000 gpm solution system.
Reported as good by
steel industry re-
presentative
4-stand
tandem cold
rolled
steel.
5-stand
tandem cold
rolled
sheets.
1 - flat bed filter
2500 gpm solution system.
2 - flat bed filters -
flotation reservoir.
9400 gpm soluble oil and
water coolant system.
Reported as good by
steel industry repre-
sentative
5-stand
tandem.
2 - tramp oil skimmers
2 - flat bed filters.
Reported as good by
steel industry repre-
sentative
5-stand
tandem.
YY.-2
4 - flat bed filters.
8000 gpm coolant system.
3000 gpm detergent system.
Reported as good by
steel industry repre-
sentative
63
-------
TABLE 7
Hot Coatings - Galvanizing
PRODUCTION
FACILITIES
WASTEWATER TREATMENT
BASIS FOR SELECTION
Combined treatment
OO-2
One type of three
distinct processes.
Recommended by equipment
manufacturer
Combined treatment
Process used only at
USS plants
180,OOOT/yr
MM-2
Combined treatment for
hot and cold coatings
Process used only at
USS plants
Process used only at
USS plants
NN-2
Third type process used
at Wheeling-Pittsburgh
plants. Reported as
good treatment by indus-
try representative
64
-------
TABLE 7
Hot Coatings - Terne Line
PRODUCTION
FACILITIES
WASTEWATER TREATMENT
BASIS FOR SELECTION
115,OOOT/yr
PP-2
Combined treatment
Reported as good by
industry representative
and mill builder
150,OOOT/yr
OO-2
Combined treatment
Reported as good by
industry representative
and mill builder
Combined treatment
Reported by mill builder
65
-------
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a high affinity for oxygen, and (2) a high affinity for
carbon. The first promotes the corrosion resistance of
stainless steels, but it similarly provides that no chromium
metal occurs free in nature. All important ores contain
chromium as an oxide usually associated with the oxides
of other metals, particularly iron and aluminum as well as
silica, the oxide of silicon.
Affinity for carbon enforces a second restriction on the
melting of stainless steel. Truly stainless steels, to
attain the "passivity" which is their hallmark, must be low
in carbon content. It is passivity, or "inertness to
corrosion", that is the objective in the making of stainless
steel. This phenomenon is thought to be due to the
formation of an oxide layer by the iron-chromium combination
as a result of the corrosive action of oxygen. The precise
nature of this "passivation" is not fully understood.
Nickel stands next to chromium in importance as an alloying
element in stainless steel and, in addition to conferring
valuable mechanical properties, considerably extends the
resistance to corrosion by neutral chloride solution, such
as seawater, and by acids of low oxidizing capacity. This
statement, however, can only be applied to the austenitic
Class III steels which contain nickel in amounts greater
than 6 or 7 percent. When fully austenitic, that is,
containing no other phases such as ferrite, the chromium-
nickel steels are the finest of all stainless alloys from
the combined standpoints of engineering properties and
corrosive resistance. Furthermore, the presence of nickel
definitely broadens the range of passivity established by
the chromium.
Plain carbon steels are predominantly distinguished by their
carbon contents and micrestructures, and secondarily by
residual elements and gases or their reaction products.
Carbon steel grades are specified by the content of carbon,
manganese, silicon, phosphorous, and sulfur; lead and copper
contents are specified as added elements to standard steels.
Carbon and manganese are the elements of primary importance.
Phosphorous, sulfur, silicon, and sometimes copper are
undesirable residual elements. Lead is added for free-
machining steels and copper is sometimes added to improve
corrosion resistance. The microstructure of the steel
depends primarily upon the steelmaking process, which
determines residual alloys, non-metallic and gas contents,
and upon the final rolling, forging, or heat-treating
operation. Carbon steels always contain carbon, manganese,
phosphorous, sulfur, and silicon; they may contain small
amounts of other elements. These other elements include
68
-------
gases such as hydrogen, oxygen, or nitrogen introduced
during the steelmaking process; nickel, copper, molybdenum,
chromium, or tin which may be present in the scrap; and
aluminum, titanium, vanadium, or zirconium introduced during
the deoxidation process. Carbon steels thus contain other
elements, but are not alloy steels by definition.
Alloy steels are defined as those which owe enhanced
properties to the addition of one or more special elements
or to the presence of larger proportions of elements such as
manganese or silicon than are ordinarily present in carbon
steel. The principal classifications are:
1. High-strength low-alloy steels
2. AISI alloy steels (constructional alloy steels)
3. Alloy tool steels
4. Stainless steels
5. Heat-resisting steels
6. Electrical steels (silicon steels)
The AISI alloy steels or constructional alloy steels
represent the largest tonnage group. Stainless steels are
those alloy steels which contain 4 percent or more of
chromium. The alloying elements in tool steels are added to
increase hardenability; to form hard, wear-resisting alloy
carbides; and to increase resistance to softening on
tempering. The high-speed tool steels are alloyed to
contain large amounts of wear-resisting carbides and to
promote resistance to softening at high temperatures. The
high-strength low-alloy steels are used primarily in the
construction of transportation eguipment, but are
increasingly finding application in bridges, and as exposed
structural members. Electrical steels contain up to 5
percent silicon and most are used in sheet form for the
cores of electrical equipment providing high permeability,
high electrical resistance, and low hysteresis loss. Heat-
resisting steels refer generally to high chromium and nickel
alloys employed in equipment designed to operate above 538°C
(1000°F). Two of the many proprietary grades available are
COR-TEN and MAYARI-R.
Published information on the grades of steel produced in
various plants is weakest in that alloy grade production is
indicated along with carbon steel production whenever even
the smallest amounts of any alloy steel is or has been pro-
duced. From the data in the Final Progress Report, EPA
Grant Project R800625, "Water Pollution Practices in the
Carbon and Alloy Steel Industries", there are some 46 plants
which make stainless steel or which make alloy steels
exclusively in one or more furnaces. Most of the other 92
69
-------
plants for which steelmaking furnaces are detailed in that
report, reportedly produce some alloy steel; these generally
would be plants in which alloy production is "indistinguish-
able from carbon steel production". The 46 specialized
plants are listed in Table 2; these plants account for most
of the alloy and stainless steel production.
Anticipated Industry Growth
Steel in the United States is a $22.HI billion a year
business. The industry is third in the nation, behind the
automotive and petroleum industries, in the value of its
total shipments and, with 487,000 employees, is second only
to the automotive industry in the number of people who work
for it. Over the decade since 1962, the steel industry has
grown 60% from sales of $14.0 to $22.47 billion.
In 1972 steel climbed back from its worst market in over a
decade showing a steady improvement in the early part of the
year. Both raw steel production and finished mill product
shipments were up substantially from 12 year lows reached
late in the summer of 1971. As steel demand improved, so
did steel employment. The number of persons carried on
domestic steelmaker payrolls increased steadily during the
first quarter, after hitting a 32 year low in November,
1971. Just how fast the economic position of the nation's
steel industry improves, however, depends to a large extent
on one important imponderable: imports. In the first two
months of 1972, for instance, foreign steel accounted for
oneseventh of the nation's apparent steel consumption.
Description of Operations to Make Steel
Steelmakinq Operations
There are three primary methods in use today for the produc-
tion of steel, the electric arc furnace, the open hearth
furnace and the basic oxygen furnace. The reader is
referred to the "Development Document for Effluent
Limitations Guidelines and New Source Performance Standards
for the Steelmaking Segment of the Iron and Steel Industry"
(EPA-440/l-74-024-a) for a complete discussion of the
steelmaking, vacuum degassing and continuous casting
operations. The discussion following focusses particularly
on specialty steelmaking operations.
Raw steel production by type of furnace and grade of steel
in 1971 is shown in Figure 1. Alloy steels are produced, as
shown, in the open hearth and basic oxygen furnaces in about
70
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71
-------
the same relative proportions as is carbon steel. The
electric furnace produces a much higher percentage of alloy
steel and virtually all of the stainless steel. Unusual is
Allegheny Ludlum Steel Corporation's Natrona Plant
production of a variety of stainless steels in their 114"
hot blast cupola and basic oxygen furnaces. The first
stainless steel was tapped from the EOF vessel in 1968 and
has produced 72,700 tons through May, 1972.
A flow sheet indicating principal steps in the production of
stainless steel products is shown in Figure 2.
The electric-arc furnace is uniquely adapted to the
production of high-quality steels; however, most of the
production is carbon steel. Practically all stainless steel
is produced in electric-arc furnaces. Electric furnaces
range up to 9 meters (30 feet) in diameter and produce from
1.8 to 365 kkg (2 to 400 tons) per cycle in 1.5 to 5 hours.
The production of stainless steels is one of the most
difficult arts practiced by fine steelmakers. These steels
are normally melted in electric arc furnaces, with the
exception of certain high purity or very specialized grades
which are made in induction furnaces, either in air or in a
vacuum, the latter technique being more particularly used
when low carbon contents are specified. The latest
developments are the consumable-electrode vacuum arc
furnace, and the A-O-D process in which an arc-melted
product is blown in a converter-like vessel in an argon-
oxygen atmosphere.
The arc furnaces used in the production of stainless steels
vary in capacity from 1.8 to 22.7 metric tons (2 to 25
tons) , and may range up to 64 or even 180 metric tons (70 or
even 200 tons) . A basic (magnesite) lining is used, since
the basic process provides scope for all the refining
operations required. There is an increasing tendency to use
chromite walls and a magnesite hearth. A cross-section
diagram of a Heroult electric- arc furnace is shown in
Figure 3. Stainless steels can be made by the traditional
procedure of oxidation followed by refining in reducing
conditions and finally the addition of the special alloying
elements. Alternatively there are various special
techniques, some of which include oxygen injection.
The Traditional Stainless Steelmaking Procedure
The furnace is charged with good quality carbon steel scrap,
limestone, iron ore and nickel or ferronickel.
72
-------
Figure 2
FLOW SHEETS INDICATING GENERAL PRMCIPLE STEPS IN THE PRODUCTION OF STAINLESS-STEEL PRODUCTS
PRODUCTION OF
BLOOMS BU.ETS AND MRS
PRODUCTION OF
SHEET AND STRIP
PRODUCTION OF
SLABS AND PLATES
MELT IN ELECTRIC FURNACE
I HOOT I
MELT IN ELECTRIC FURNACE
I INGOT I
MELT IN ELECTRIC FURNACE
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The charge is melted down at a high temperature, under
highly oxidizing conditions. The oxidizable elements are
either transferred as oxides to the slag or evolved as
gaseous compounds. If the scrap contains any chromium, this
is largely oxidized and reverts to the slag, whereas the
less readily oxidized metals such as nickel and copper
remain in the bath.
Modifications of The Normal Procedure
The procedure just described has certain disadvantages.
-First and foremost, it entails charging the furnace
initially with chromium-free scrap, since any chromium
originally present will be oxidized during this stage of the
melting and lost to the slag. In other words, stainless
steel scrap cannot be recovered, and the stages subsequent
to oxidation must be hurried through with all speed if very
low carbon contents are to be attained and held. Type 18-8
steel scrap, however, is an important source of secondary
nickel in the industry.
The first modification thus consists of utilizing charges
that contain stainless steel scrap, and melting them down as
rapidly as possible under reducing conditions to avoid
losing the chromium to the slag. At melt-down the bath is
analysed with minimum delay and the appropriate correcting
additions of alloying elements made. The silicon content is
adjusted to within specification and the furnace is then
ready to tap. While it is certainly interesting from the
cost point of view, this procedure can do nothing to control
the phosphorus and carbon contents.
The second modification still requires a charge of very low
phosphorus content, but uses very high melting temperatures
to control the carbon content, so that the life of
refractories is seriously affected. A charge of high-
quality scrap and chromium steel is melted as rapidly as
possible, together with nickel or ferronickel, under
slightly oxidizing conditions. The slag at melt-down should
contain as little Cr2O3 as possible.
When the bath analysis has been obtained, oxygen is injected
at a rapid rate, regulating the total quantity (injection
time) to obtain a final carbon content below the specified
range. The bath is analysed again to determine how much
chromium has reverted to the slag.
The oxides of chromium, manganese and iron in the slag are
now reduced back into the metal by adding silicon in the
form of powdered ferrosilicon or still better Fe-Cr-Si
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alloy, which has the advantage of introducing chromium in an
economical form. It is essential to calculate the exact
amount of silicon required to reduce the slag without
lowering,its basicity unduly.
The reducing stage is the critical phase of the entire melt,
and care must be taken to maintain stable and reproducible
conditions. The melt is finished by adding the alloys
required to meet the final specification.
Whatever the other details of the procedure, the finishing
stages invariably consist in adding deoxidizers to refine
and reduce the bath. The temperature is brought back to the
normal tapping range, if it has been superheated previously,
and if desired the final killing additions are then made.
Steelmaking in The Induction Furnace
Although the major proportion of all stainless steels is
made in arc furnaces, induction furnaces are used for
certain categories of special steels and alloys.
The metal in an induction furnace is contained in a
refractory crucible, protected from contamination by furnace
gases or electrodes; its temperature can be controlled with
ease and the recoveries of all alloying elements charged
into the crucible are almost 100 percent. Steels of high
purity can be produced; in particular, the absence of
external sources of carburization facilitates the production
of very low carbon grades.
The advantages of the induction furnace are, of course, to
be weighed against its disadvantages. Since everything that
is charged is recovered in the steel, the charge materials
must be selected with extreme care. No refining or
purification is possible, with the exception of
decarburization; by melting under oxidizing conditions, it
is possible to reach extremely low carbon contents, provided
the condition of the refractories is carefully watched.
With this provison, the induction furnace is the best choice
for melting stainless steels and creep-resisting alloys to
very tight specifications on composition.
Vacuum Melting
Vacuum melting is being increasingly used for the more
highly specialized steels and alloys, particularly those
that contain readily oxidized elements. Two types of
commercial equipment are already in use, i.e. the vacuum
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induction furnace and the vacuum consumable-electrode arc
furnace. The vacuum induction furnace is illustrated in
Figure 4. The induction furnace is very well adapted to
melting in a vacuum or under controlled atmospheres. There
are no specific difficulties in enclosing the furnace in a
sealed chamber, which can be evacuated or filled with gases
other than air. Vacuum fusion is the only way of shifting
the equilibrium in the reaction FeO + C = CO + Fe in the
direction reguired to produce stainless steels with very low
carbon contents (below 0.02X). 0.02X Carbon is the limiting
carbon content at which a fully austenitic 18/8 stainless
steel will remain totally immune to intergranular corrosion,
whatever its condition, in the absence of stabilizing
additions.
Research in this field led to the commercial development, in
1935 in France, of the vacuum melting of extra-soft
stainless steels with carbon contents in the range of 0.01-
0.02 percent.
The vacuum induction furnace greatly facilitates the
addition of very readily oxidized elements such as titanium
or aluminum. Specifications can be met with a very small
range of variation in composition and a high degree of
reproducibility.
The consumable-electrode vacuum arc furnace has more
recently opened up fresh avenues. One such furnace (Figure
5.) is built up on a copper ingot mold, cooled by
circulating water, integral with the furnace casing. The
latter is connected to a pumping unit and contains the
consumable electrode clamped in a sliding terminal. The arc
is struck between the tip of the electrode and a heap of
scrap placed on the crucible floor, and the electrode is
slowly fed downwards as it melts away and the level of metal
in the crucible rises.
The prime feature of this procedure is that the metal is
melted out of contact with refractories and is subject to
the combined action of vacuum and very high temperatures.
Its impurity content is reduced and the ingot is
outstandingly clean.
Basic Oxygen Furnace Operation
The basic oxygen furnace steelmaking process is a method of
producing steel in a pear-shaped, refractory-lined, open
mouth furnace with a mixture of hot metal, scrap and fluxes.
Pure oxygen is injected at supersonic velocities through a
water cooled, copper tipped steel lance for approximately 20
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Figure 5
SCHEMATIC REPRESENTATION OF A CONSUMABLE ELECTRODE FURNACE
ELECTRODE
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minutes with a total tap-to-tap cycle of approximately 45
minutes. As this process is exothermic (heat generating), a
definite percentage of steel scrap can be melted without use
of external fuel requirements. The general ratio is about
70% hot metal and 30% scrap. The furnace is supported on
trunnions mounted in bearings and is rotated for tapping
(pouring) of steel ladles and dumping the slag.
The waste products from this process are heat, airborne
fluxes, slag, carbon monoxide and dioxide gases, and oxides
of iron (FeO, Fe2O3, FeK>4) emitted as submicron dust.
Also, when the hot metal (iron) is poured into ladles or the
the furnace, submicron iron oxide fume is released and some
of the carbon in the iron will precipitate out as graphite,
commonly called kish. All of these contaminants become
airborne. Fumes and smoke are again released when the steel
is poured into steel holding (teeming) ladles from the
furnace. Approximately 2% of the ingot steel production is
ejected as dust.
The basic oxygen furnaces are always eguipped with some type
of gas cleaning systems for containing and cooling the huge
volumes of hot gases (1,650°C) and submicron fumes released.
Water is always used to quench the off-gases to temperatures
where the gas cleaning equipment can effectively handle
them. Two main process types of gas cleaning systems are
used for the basic oxygen furnace: precipitators and venturi
scrubbers. For the venturi scrubbers, the gases are
quenched and saturated to 80°C whereas for the precipitators
the gases are cooled to approximately 250°C.
As the main gas constituent released from the process is
carbon monoxide, it will burn outside of the furnace if
allowed to come in contact with air.
The major gas cleaning systems in use today purposely
furnish air for the burning of this gas. An open hood just
above the furnace mouth is provided for the burning and
conveying of gases and fumes to the gas cleaning system.
The hoods themselves are made in several different geometric
configurations (round, square, octagonal) and are either
water cooled or are waste heat, steam generating boilers. A
special type of wet venturi scurbber and hood is sometimes
used where the hood clamps tightly over the furnace mouth
and prevents the carbon monoxide gas from burning. The gas
is then either collected for fuel or burned at the stack
outlet.
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If venturi scrubbers are used, the majority of the airborne
contaminants are mixed with water and discharged as an
effluent. Generally, water clarification equipment is
provided for treatment of this effluent.
In the ease of precipitators, two approaches are used for
quenching (cooling) the gases. One is to have an exact heat
balance between water required and gas cooling; no effluent
is discharged in this case as all of the water is
evaporated. The other approach is to pass the gas through a
water spray thus oversupplying the water which is discharged
as an effluent. This is commonly referred to as a spark box
chamber whereas the other is an evaporation chamber.
Vacuum Degassing Operation
In the vacuum degassing process, steel is further refined by
subjecting the molten steel to a high vacuum (low pressure).
This process further reduces hydrogen, carbon, and oxygen
content, improves steel cleanliness, allows production of
very low carbon steel and enhances mechanical properties of
the steel. Vacuum degassing facilities fall into three
major categories:
1. Recirculating degassing, where metal is forced into
a refactory-lined degassing chamber by atmospheric
pressure, exposed to low pressure (vacuum) and then
discharged from chamber.
2. Stream degassing in which falling streams of molten
metal are exposed to a vacuum and then collected
under vacuum in an ingot mold or ladle.
3. Ladle degassing, where the teeming ladle is
subsequently positioned inside a degassing chamber
where the metal is exposed to vacuum and stirred by
argon gas or electrical induction.
The recirculatory systems are of two types D-H (Dortmund
Border) and the R-H (Ruhrstal-Heraeus).
The R-H system is characterized by a continuous flow of
steel through the degassing vessel by means of two nozzles
inserted in the teeming ladle molten steel while the D-H
system is characterized by a single nozzle inserted in the
molten steel. The R-H system degassing chamber and ladle
are stationary while the D-H system ladle oscillates up and
down.
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A four or five stage steam jet ejector with barometric
condenser is used to draw the vacuum. A means of providing
heat is furnished in the process by electric carbon heating
rods to replace heat loss in the process or in some cases to
raise the temperature of the steel bath. Alloys are
generally added during this process and cycle time is
approximately 25 to 30 minutes.
The waste products from vacuum degassing process are
condensed steam and waste with iron oxide fumes and CO gases
entrained in the discharge effluent.
More specific details of the vacuum degassing process are
shown on Figure 7.
Continuous Casting Operation
Steel that is not teemed into ingot molds can be cast in a
process known as continuous casting. In the continuous
casting process billets, blooms, slabs and other shapes are
cast directly from the teeming ladle hot metal, thus elim-
inating the ingots, molds, mold preparation, soaking pits
and stripping facilities. In this process, the steel ladle
is suspended above a preheated covered steel refractory
lined rectangular container with several nozzles in the
bottom called a "tundish". The tundish regulates the flow
of hot steel from teeming ladles to the continuous casting
molds by means of nozzle orifice size, ferrostatic head or
using stoppered nozzles to shut off the flow of steel.
When casting billets or blooms, several parallel casting
molds are served by one tundish. Each mold and its associa-
ted mechanical eguipment is called a "strand" and casting
units are generally two, four, or six strand machines.
The casting molds are water-cooled copper molds, chrome
plated conforming to the desired shape to be cast. To start
the casting process, a dummy bar is fed back into the strand
and blocks the bottom of the mold opening. As the hot steel
flows through the tundish nozzles into the casting mold, a
hard steel exterior shape forms from the cooling with a
molten steel center. The casting molds oscillate to prevent
sticking and help discharge the solidified product from the
mold. After the cast product is discharged from the molds,
the cast product enters a spray chamber where sprays further
cool the cast product. After the spray section, the cast
product is either cut off by a shear or acetylene torch and
product tipped to the horizontal for discharge through the
"run-out" table and stacker units or the product is curved
to the horizontal by means of bending rolls. After the
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product is in a horizontal direction, it is re-straightened
and then cut to desired length. The curved type of machine
reduces the height requirements of the casting machine
building.
Three water systems serve the casting machine; they include
mold cooling, machine cooling and spraying. Mold and
machine cooling are performed in closed recycle systems
whereas the spray water is an open recycle system. The
waste products from this process are iron oxide scale, oil
contaminants from machinery, heat and a limited amount of
gases from the acetylene torch cut off units. At the
discharge zone of the spray chamber, "pinch rolls" regulate
the speed of discharge of cast product from the molds. The
casting strand contains other rolls called "apron" rolls and
"support" rolls which keep the cast product in proper
alignment.
More specific details of the continuous casting operation
are shown on Figure 8.
Hot Forming and Shaping Operations
Hot Forming Primary
The hot forming and cold finishing operations exist in such
variety that a simplified description is difficult. In
general, the hot forming primary mills reduce ingots to
slabs or blooms whereas the secondary mills reduce slabs or
blooms to billets, plates, shapes, strip, etc. The cold
steel finishing operations involve a number of processes
that do little to alter the dimensions of the hot rolled
product, but which impart desirable surface or mechanical
characteristics to the product. The product flow of these
typical steel mill operations is shown in Figure 9.
It is possible, and often economical, to roll ingots
directly through the bloom, slab, or billet stages into more
refined and even finished steel products in one mill in a
continuous operation, frequently without any reheating.
Large tonnages of standard rails, beams, and plates are
produced regularly by this practice from ingots of medium to
large size. Most of the ingot tonnage, however, is rolled
into blooms, slabs, or billets in one mill, following which
they are cooled, stored^ and eventually rolled in other
mills or forged.
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Blooms and Slabs
Hot forming defines the initial stages in forming useful
products from steel ingots by hot rolling. The initial
stages consist of a series of hot rolling operations in
which the steel ingot cross-section is reduced to either a
square, oblong, or rectangular cross-sectional shape and
proportionately increased in length. Steel ingots are
originally tapered and 2 to 3 ft in cross-section and 5 to 9
ft in height.
The hot steel ingots are transferred to the primary mills
for rolling from soaking pit furnaces which provide for
uniform heating of the steel ingots to the desired rolling
temperature, usually 1,180° to 1,340°C (2,156° to 2,444°F)
and also acts as a storage area to compensate for production
variations in the flow of steel ingots between the
steelmaking facilities and primary rolling mills. The
soaking pit furnaces consist of square, rectangular, or
circular, fuelfired (oil, gas, etc.) refractory lined pits
constructed with the top of pits several feet above ground
level and installed usually in rows under cover of a
building adjacent or within the primary mill to be served.
The ingots are placed into the soaking pits in an upright
position through openings in the top. Removable covers
close the pit openings.
The soaking pit furnace bottoms are made up using a 12 in.
to 16 in. thick bed of coke breeze and when the bed becomes
burned and contaminated with iron oxide scale, and other
alien material, it is removed through cinder holes in the
furnace pit bottoms and new 12 in. to 16 in. bed is
installed.
The pits are spanned by one or more cranes equipped with
ingot lifting tongs for placing and removing the steel
ingots as required. The crane removes the properly heated
steel ingots and places them into an electrically-driven
ingot transfer car which automatically delivers the ingots
to the primary rolling mill.
The first rolling mill stages of the hot forming operations
are identified as primary breakdown mills called blooming or
slabbing mills. The basic operation in a primary mill is
the gradual compression of the steel ingot between the
surfaces of two rotating rolls, and the progression of the
ingot through the space between the rolls. The physical
properties of the ingot prohibit making the total required
deformation of the steel in one pass through the rolls, so a
number of passes in sequence are always necessary. As the
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ingot enters the rolls, high pressure water jets remove
surface scale. The ingot is passed back and forth between
the horizontal and vertical rolls while manipulators turn
the ingot from time to time so that it is well worked on all
sides. When the desired shape has been achieved in the
rolling operation, the end pieces or crops are removed by
electric or hydraulic shears. The semi-finished pieces are
stored or sent to reheating furnaces for subsequent rolling
operations. The cross-section of final rolled product
determines whether the mill is identified as a blooming or
slabbing mill. Generally slabbing mills produce rectangular
slab shapes 2 in. to 6 in. thick and 24 in. to 60 in. wide
and blooming mills in the range of 6 in. x 6 in. to 12 in. x
12 in. square blooms in cross-section and lengths of
products may be up to 90 ft. The primary mills furnish
steel slabs or blooms either directly or through reheating
furnaces to secondary finishing or section mills. The
slabbing mills furnish slabs to flat rolling mills, such as
hot strip mills or plate mills; and blooming mills furnish
blooms for billet mills, bar and rod mills, structural and
rail mills, narrow strip mills, and beam mills. Products
from the bar, rod, and narrow strip (sometimes referred to
as skelp) mills, can be further rolled to produce pipe or
tubing.
Many of the primary mills are presently being replaced by
the continuous casting process referred to as billet, bloom,
or slab casting machines. The casting machines then in turn
furnish the steel slabs or blooms to the section mills. For
description and effluent guidelines for continuous casting,
see, "Steel Making Segment of the Iron and Steel
Manufacturing Point Source Category", June 197<*.
As noted above, during the rolling operations the cooling
water is sprayed externally over the table and mill stand
rolls. This water is discharged to trenches beneath the
rolling mill equipment. When the steel ingot enters the
rolling mill stands, high pressure (2,000 psi) descaling
water is sprayed over the hot steel ingot to flush away any
iron oxide scale that forms. Generally, about UX of this
cooling water evaporates, and the balance is discharged to
an iron oxide scale and water collection system. Iron oxide
scale generation may amount to 8-10S of the throughput steel
production.
Ever increasing attention is being devoted to the
conditioning of semi-finished products as the requirement
for high qualities of steel products increases. Major
elements in this area involve the need for removing surface
defects from blooms, billets, and slabs prior to shaping, as
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by rolling into a product for the market. Such defects as
rolled seams, light scabs, checks, etc., generally retain
their identity during subsequent forming processes and
result in products of inferior quality.
These surface defects may be removed by hand chipping,
machine chipping, scarfing, grinding, milling, and hot steel
scarfing. The various mechanical means of surface
preparation are those common in all metal working amd
machine shop operations. Scarfing is a process of supplying
streams of oxygen as jets to the surface of the steel
product under treatment, while maintaining high surface
temperatures that result in rapid oxidation and localized
melting of a thin layer of the metal. The process may be a
manual one consisting of the continuous motion of an
oxyacetylene torch along the length of the piece undergoing
treatment. In recent years the so-called hot scarfing
machine has come into wide use. This is a production
machine adapted to remove a thin layer (1/8 in. or less) of
metal from all steel passed through the machine in a manner
analogous to the motion through rolling mills.
Reheating is necessary throughout the rolling operation
whenever the temperature of the metal being worked falls
below that necessary to retain the required plasticity.
Reheating furnaces are* of two general classes, batch and
continuous types. Batch furnaces are those in which the
charged material remains in a fixed position on the hearth
until heated to rolling temperature. Continuous furnaces
are those in which the charged material moves through the
furnace and is heated to rolling temperature as it
progresses toward the exit. One unique type of reheating
furnace is the rotary hearth type used frequently for
heating rounds in tube mills and for heating short lengths
of blooms or billets for forging. The rotary hearth type
permits external walls and roof to remain stationary while
the hearth section of the furnace revolves. Batch furnaces
vary in size from those with hearths of only a few feet
square to those 20 ft in depth by 50 ft long; some modern
continuous furnaces have hearths 80 to 90 ft long.
Blooms from the primary mill are further processed into a
variety of products. The products are rails and joint bars,
structural and other sections, and billets which are further
processed to tube rounds, bar and rod, wire, and special
products.
A wide variety of steel shapes are rolled from blooms; these
shapes include structural sections such as I-beams,
channels, angles, wide flanged beams, H-beams, sheet piling,
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rails, and numerous special sections. The heating of the
bloom for large sections is usually done in batch type
furnace, although some newer mills use continuous furnaces.
A typical mill consists of a two high reversing breakdown
stand in which initial shaping is accomplished, followed by
a group of three roll stands in train where the rolling
process is completed; these mills are known as roughing
stands, intermediate stands, and finishing stands. Several
passes of the material are made back and forth through the
breakdown, roughing and intermediate mills; a single pass is
usually made through the finishing stand. The seguence of
operations then consists of heating bloom, rolling to proper
contour dimensions, cutting while hot to lengths that can be
handled, cooling to ambient temperature, straightening,
cutting to ordered lengths, and shipping.
More specific details of the blooming and slabbing
operations are shown in Figure 10.
Rails
Rails are formed from heated blooms in various mill
arrangements, but the formation may be considered as taking
place in three steps or stages. The first stage is the
roughing where the bloom is reduced in section and
elongated. High pressure sprays are used at the discharge
of the roughing stands for scale removal. The second, or
intermediate stage, proceeds with the forming of the rail
and involves a combination of slabber, dummy, former, edger,
and leader passes, depending on the mill layout. The third
stage is the finishing pass which completes the formation of
the desired rail section.
The rails are conveyed from the finishing stand on a runout
table to hot saws which cut the product to the normal
standard 39 ft rail length. After sawing the rails are
stamped, cambered, and weighed before they are advanced to
cooling beds. Rails intended for railroad service must be
control cooled in containers to prevent the formation o'f
internal thermal ruptures or cracks. After cooling the
rails are conveyed to the finishing operations. The
finishing consists of inspection, removal of saw burrs,
straightening, drilling, grinding of ends, leveling,
inspection, classification, and painting. The rails are
then ready for storage and shipment.
Rail-Joint Bars
Joint bars are rolled from heated blooms or billets similar
to rails. Additional passes are required if the joint bar
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has a depending flange, or long toe. The finishing
operation consists of hot-working and oil-quenching the
joint bars. In this operation the product is cold sheared
to length and then reheated for hot-working which consists
of punching, slotting, straightening, and guenching in an
oil tank.
Hot Forming - Section
Billets
Modern billet mills utilize continuous lines which have
alternate horizontal and vertical stands. The blooms are
normally passed through hot-scarfing machines after leaving
the bloom shears. The scarfing head of the machine contains
oxyacetylene burner nozzles to remove defects from the
surface of the blooms. Fume control equipment is required,
and water sprays carry the iron oxide waste through a trench
under the mills to a collection system. Metal loss in the
scarfing operation is generally 2% to 3% of the product.
The bloom is now conveyed to the continuous billet mill
stands. The continuous mill consists of a series of roll
stands, arranged one after the other so that the piece to be
rolled enters the first stand and travels through the mill,
taking but one pass in each stand of rolls and emerging from
the last set as a finished product. Descaling water and
cooling water are sprayed at the stands and rolls with the
discharge going to trenches under the mills.
After the billet mills the product is cut to the desired
finish piece length. The cutting is accomplished by
stationary shears, movable gang shears, flying shear, flame
cutting, or saws. Shears are faster but distort product
ends. Flying shears are used on small billets to eliminate
long tables and transfers. Saws and flame cutting eliminate
distorted ends but are slower and require maintenance and
expensive fuels.
After cutting, the billets are stamped for proper
identification of heat number so the product may be properly
routed. The billets are cooled on cooling beds, or hot beds
and then pushed into cradles, from which they can be loaded
into cars for shipment or transferred for further
processing.
Billets are transferred to the bar mill or merchant mill for
processing into finished products. The billets are heated
to rolling temperature in a continuous reheat furnace. The
billets are fed into one end and moved through the furnace
by a billet pusher. A walking beam furnace is sometimes
95
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utilized to eliminate the slide marks on the underside of
the billets. A billet ejector, normally a pusher bar type,
pushes the end billet out of the side of the furnace. A
shear cuts the heated billets to size or removes bent ends
prior to conveying the billet to the bar mill.
Modern bar mills are normally arranged in a cross-country
design or continuous design. Both types have in-line
roughing stands but the cross-country mill has side by side
intermediate and finishing stands where the continuous mill
has all stands in-line. The continuous mill is more
efficient for production runs but reguires more space and
individual motors on each stand. Descaling and cooling
water sprays are employed at the mill stands with the
discharge going into trenches under the mill to collection
systems.
Various products are rolled in the bar mills such as angles,
channels, flats, other small sections, rebar, window sash,
fence posts, rounds, wire, and flat narrow strip. These
various products are conveyed to a cooling bed. After
cooling the product is sheared to proper length, marked for
identification, sometimes straightened, bundled or coiled,
and weighed for shipment or further processing.
Structural and Other sections
Structural sections include standard items, such as I-beams,
channels, angles, and wide-flange beams, and special
sections such as zees, tees, bulb angles, and car-building
center sills. Other sections include such miscellaneous
shapes as sheet piling, tie plates, cross ties, and those
for special purposes.
Blooms are heated in a continuous reheat furnace and then
conveyed to the roughing, intermediate, and finishing
stands. Passes in actual use range from fifteen roughing
and nine intermediate on sections requiring heavy overall
work, to two fine roughing, and three intermediate on the
sections requiring a minimum of work. In all cases, the
intermediate passes are followed by a single finishing pass.
In rolling wide-flange beams it is customary to roll a bloom
which has, as nearly as possible, the same proportions as
the finished beam.
Rolled material from the structural mills is delivered by
roller table to the hot saw. This equipment consists of a
circular saw with large quantities of cooling water to
maintain the cutting edges. Cuts are usually made at the
hot saw to remove the crop ends, to part the usable material
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into lengths that can be handled for further processing, and
to provide short test pieces. The shapes are then cooled on
a cooling bed. After cooling the shapes are conveyed to the
finishing area where they are straightened, cold sheared or
cold sawed, and inspected prior to separating and assembled
for shipment.
Merchant-bar, rod, and wire mills produce a wide variety of
products in continuous operations ranging from shapes of
small size through bars and rods. The designations of the
various mills as well as the classification of their
products are not very well defined within the industry; in
general, the small cross-sectional area and very long
lengths distinguish the products of these mills. Raw
materials for these mills are reheated billets. Many older
mills use hand looping operations in which the material is
passed from mill stand to mill stand by hand; newer mills
use mechanical methods of transferring the material from
stand to stand. As with other rolling operations the billet
is progressively squeezed and shaped to the desired product
dimensions in a series of rolls. Water sprays are used
throughout the operation to remove scale.
More specific details of sectional type mill operations are
shown on Figure 11.
Hot Forming - Flat
Plate Mills
Plates are classified, by definition, according to certain
size limitations to distinguish them from sheet, strip, and
flat bars. According to this classification, plates are
generally considered to be those flat hot-rolled finished
products that are more than 8 in. wide and generally 0.23
in. or more thick, or over 48 in. wide and at least 0.18
in. thick. Sequence of operations for plate mills is
heating of slabs, descaling, rolling, leveling, cooling, and
shearing. Most plate mills use continuous type heating
furnaces. Descaling in modern plate mills is accomplished
by hydraulic sprays impinging on both top and bottom
surfaces and operating at pressures up to 1,500 Ibs per sq.
in. Temperature variation in the plate from the front to
the back is a problem of particular importance in rolling
plates, as is the care that must be exercised in cooling the
rolled product so as to avoid distortion.
The basic operation of a plate mill is the reduction of a
heated slab to the weight and dimensional limitations
defining plates. This is accomplished by heating the slabs.
99
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descaling, rolling to plate, leveling or flattening,
cooling, and shearing to desired size.
Slabs are received from the slabbing mill or roller tables
or removed from storage by overhead cranes and placed on a
charging table at the entry end of reheat furnaces. The
slabs are removed through a continuous type reheat furnace
by pushing the last piece charged with a pusher at the
charging or entry end of the furnace. The reheat furnace
heats the slabs to rolling temperature up to approximately
1,230°C (2r250°F). As each cold slab is pushed into the
furnace against the continuous line of material, a heated
piece is removed. The heated slab is discharged from the
furnace by gravity upon a roller table which feeds the mill.
Heated slabs are conveyed on a roller table to a scale-
breaker stand. As the slab exits from the scale-breaker,
primary descaling is completed on the delivery side of the
mill as the slab is passed through top and bottom high
pressure hydraulic sprays operating at 1,000 psi to 1,500
psi. The scale-breaker and sprays flush away iron oxide
scale that forms on the surface of the hot slabs.
Generally, about H% of the spray water evaporates and the
balance is discharged through a trench under the mills to an
iron oxide and water collection system. Iron oxide scale
generation may amount to 8-1056 of the throughput steel
production. During the rolling operations, cooling water is
sprayed externally over the table and mill stand rolls.
Additional lubrication of mill stand rolls is provided at
intervals by shots of water-soluble oil.
The descaled slabs are conveyed on roller tables to the
plate mill. There are various types of plate mills such as
three-high mills, four-high reversing mills, tandem mills,
semi-continuous and continuous mills. In each of the
various plate mills the heated slab is reduced to the
desired plate size. Cooling water, spray water, and water-
soluble oil is sprayed externally over the mill stand rolls.
Hydraulic sprays on both sides of the mill stands, operating
at high pressure, are utilized for top and bottom secondary
scale removal.
The plates are conveyed on a runout table to a leveler. A
portion of the runout table is equipped with a series of
cooling sprays. After leveling, the plates are cooled
uniformly to avoid localized stresses which would set up
permanent distortions. After cooling, the plates are
conveyed to end and side shears to be cut to proper size and
then into a shipping or storage building.
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More specific details of a plate mill operation are
presented on Figure 12.
Hot Strip Mills
The continuous hot strip mill utilizes slabs which are
brought to rolling temperatures in continuous reheating
furnaces; the conditioned slabs pass through scale breakers
and high pressure water sprays which dislodge the loosened
scale. A series of roughing stands and a rotary crop shear
produce a section that can be finished to a coil of the
proper weight and gauge. The second scale breaker and high
pressure water sprays precede the finishing stand train in
which the final size reductions are made. Cooling water is
applied through sprays on the run-out table, and the
finished strip is coiled. Such a mill can turn a thick 6 ft
slab of steel into a thin strip or sheet a quarter of a mile
long in three minutes or less. The modern hot strip mill
produces a product which may be up to 96 in. wide, although
the most common width in newer mills is 80 in. The product
of the hot strip mill may be sold as produced, or used
within the mill for further processing in cold reduction
mills, and for plated or coated products.
The basic operation of a hot strip mill is the reduction of
slabs to flat strip steel in thicknesses of O.OU in. to 1.25
in., widths of 24 in. to 96 in., and lengths up to 2,000 ft.
A modern wide hot strip mill will heat slabs in two or more
continuous reheating furnaces and convey the heated slabs to
a rolling train. A typical rolling train will consist of a
roughing scale-breaker, and six four-high finishing stands.
Slabs are received from the slabbing mill on roller tables
or removed from storage by overhead cranes and placed on a
charging table at the entry end of reheat furnaces. The
slabs are moved through a continuous type reheat furnace by
pushing the last piece charged with a pusher at the charging
or entry end of the furnace. The reheat furnace heats the
slabs to rolling temperature up to approximately 1,100° to
1,300°C (2,010° to 2,370°F) . As each cold slab is pushed
into the furnace against the continuous line of material, a
heated piece is removed. The heated slab is discharged from
the furnace by gravity upon a roller table which feeds the
mill.
Heated slabs are conveyed on a roller table to the roughing
scale-breaker stand for primary descaling, which is
conducted in a manner similar to plate and other hot mills.
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103
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The slabs are conveyed from the roughing scale-breaker to
the four four-high roughing stands. The first roughing
stand is normally a broadside mill used to produce widths
greater than the original slab. Slab turnarounds are
provided before and after this mill to rotate the slabs 90°
when the stand is used for broadsiding. Following the mill,
a slab squeezer serves to true up edges and widths. A slab
shear is located between the squeezer and the second
roughing stand. sheared waste is fed into a scrap bin for
recycling back to the steelmaking facilities as scrap. The
second, third, and fourth roughing stands are equipped with
vertical edging rolls mounted on the entry side of each
mill. After the roughing stands, the rolled product is
cooled on a holding table, if necessary, to attain proper
finishing temperature to meet requirements. A rotary crop
shear is installed at the end of the table, so that both the
front and back ends of the material can be squared off
before finishing. A second scale-breaker followed by high
pressure sprays is utilized to perform secondary scale
removal prior to entering the finishing stands.
Material is fed into the finishing train, which consists of
six four-high mill stands, and is continuously reduced to
strip product. Product speed leaving the last finishing
stand reaches approximately 600 meters/minute (1,970 fpm).
Loopers are provided between the finishing stands and steam
sprays are provided on the delivery side of each stand.
Strip product is conveyed from the finishing stands on a
runout table to automatic coolers. Cooling sprays,
sometimes referred to as laminar sprays, continuously cool
the product on the runout table. Similar to the mill stands
and tables, the spray water is discharged through a trench
under the mill to a water collection system. The coiled
strip product is then conveyed to storage for shipping or
further processing.
More specific details of a hot strip mill operation are also
presented on Figure 12.
Skelp Mills
Skelp is a hot rolled strip used to make butt-weld pipe or
tube. The skelp is rolled with square or slightly beveled
edges, the width of which corresponds to the circumference
of the pipe, and the gauge to the thickness of the wall. A
bloom is heated and rolled to produce skelp of the desired
size.
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The bloom which is rectangular in shape and of the proper
dimensions to produce skelp of the desired size, is heated
in a continuous reheat furnace to rolling temperature. The
bloom is then conveyed on a roller table to the mill stands.
The first two to four stands in the mill, corresponding to
roughing stands in other mills, are used to spellerize the
bloom. This means the working surfaces of the stands,
called knobbling rolls, are provided with regularly shaped
projections and depressions, while the surface of the other
passes are plain. When the bloom passes through these
rolls, the kneading process to which its surfaces are
subjected is said to give a pipe surface that is better
adapted to resist corrosion. Descaling is as described for
other hot mill operations.
The bloom, now much reduced in thickness, is edged by a
twisting guide in the next group of rolls in order to
control the width. Next, the bloom is cut into two or more
pieces by a hot shear, to adjust the length of the finished
strip to the cooling bed. These pieces then pass flatwise,
or flat and edgewise, through the next fine stands to the
vertical rolls. The vertical rolls are grooved to roll the
edges of the skelp, which must be slightly beveled, so that,
when skelp is bent to form the pipe, they will fit squarely
together and form a perfect joint.
From the finishing rolls, the skelp passes over the cooling
bed to the shears, where the crop ends are cut off, and the
remainder of the skelp strip is cut into the lengths
desired. The skelp is then passed to the clipper, a machine
that performs the double function of a shear and a press.
It shears two small triangular-shaped pieces from one end of
the skelp to start the curve for welding the pipe, and bends
the end of the skelp to facilitate handling with the welding
tongs. The skelp is stacked and transported to the butt-
welding furnaces.
Pipe and Tubes
Steel tubular products have many uses to which they have
been applied and this has led to descriptive terms in
designating the products used for different purposes.
Typical products are standard pipe, conduit pipe, line pipe,
pressure pipe, structural pipe, oil-country tubular goods,
pressure tubes, mechanical tubes, and stainless steel pipe
and tubes. Another classification is based on the methods
of manufacture, to which we will refer. On this basis, all
steel tubular products may be classified under the two main
headings of welded and seamless.
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Welded Tubular Products
Welded tubular products are classified as butt-weld, lap-
weld, or electric-weld. Butt-weld pipe or tube is made from
a hot rolled strip, with square or slightly beveled edges
called skelp, the width of which corresponds to the
circumference of the pipe, and the gauge to the thickness of
the wall. By heating this skelp to the welding temperature
and drawing it through a die or roll pass, the skelp is bent
into cylindrical shape and its edges pressed firmly together
into a buttweld, thus forming a pipe. Lap-weld is similar
except the edges are lapped. In the electric-weld process,
hot rolled strip or plate of a gauge corresponding to the
thickness of the wall of the pipe desired, but of an overall
width slightly greater than its circumference, is first
edge-trimmed to insure parallelism and accurate width. For
large diameter pipe fusion-welding is used. The plate is
bent into cylindrical shape with the beveled edges abutting
to form a "V" into which the electrode is melted. For small
diameter pipe electric-resistance welding is used, whereby
the union of the seam is affected by the application of
pressure and heat, the heat being generated by the
resistance to current flow across the seam during welding.
Butt-Welded Pipe
The butt-welded process is used in the manufacture of pipe,
1/8 in. to U in., nominal diameter. Skelp is conveyed from
storage and charged into a reheating furnace, welded in a
welding stand, and finished on finishing machines.
The skelp is charged into a continuous reheat furnace.
Modern mills used skelp strip in coils to feed a continuous
butt-welding mill. The skelp is fed into a threading
machine which feeds it through the furnace. Once the
leading end is in the forming and welding unit the threading
rolls release the skelp. The leading end of the next skelp
strip is welded to the trailing arm of the first strip by a
flash-type skelp welder, prior to the entry end of the
reheat furnace. The skelp strip exits from the furnace into
a continuous forming and welding mill. The forming stand
rolls force the skelp into an arc of about 270°. Then it
goes through a welding horn and into a welding stand, where
the edges are pressed firmly together. The last stands of
the mill contain reducing rolls which provide for reduction
of diameter and resultant change in wall thickness. A
rotary flying saw cuts the continuous pipe into lengths.
The cut lengths are reduced to the required hot size on a
sizing mill. The hot pipe is delivered to a cooling bed and
then passes to a water bosh tank for fast cooling.
106
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107
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Conveyors feed the pipe to straighteners in the finishing
bay. Details of a typical operation are shown in Figure 13-
1.
Seamless Tubular Products
Seamless tubular products are made by two processes;
piercing and cupping. In the piercing process, a solid
round bar or billet is heated, pierced and afterwards shaped
to the desired diameter and thickness of wall. This process
is used today for most of the seamless pipe products. The
cupping process is used primarily for the manufacture of
special tubes and gas cylinders. A circular sheet or plate
is forced by successive operations through several pairs of
conical dies until the plate takes the form of a tube, or
cylinder with one end closed. Details of a typical mill are
shown in Figure 13-2.
Seamless Pipe Mills
The production of seamless pipe and the mills required in
the operation will vary depending on the diameter of the
pipe product. The steps required to produce pipe up to H
in. diameter consist of heating a solid billet, piercing,
plug rolling, reeling, reheating and reducing or sizing.
Pipe up to 16 in. diameter is similar except a second
piercing and reheating operation is required. Pipe up to 26
in. diameter is similar to the preceding 16 in. operation
except for the addition of a rotary rolling mill and a third
reheating operation.
A solid bar or billet of the proper length and diameter to
make the size and weight of tube desired is heated to
rolling temperature of approximately 1,230°C (2,250°F) . The
heated billet is transferred in a horizontal trough to the
piercing mill. The piercing mill consists of two contoured
horizontal rolls and a piercing mandrel. The roll surfaces
are contoured so that, in the horizontal plane through the
centerline of the pass, the space between the rolls con-
verges toward the delivery side and then diverges to form
the pass outlet. The elevation of the centerline of the
pass is determined by guides mounted above and below the
center of the mill in the space between the rolls. Between
these guides in the pass outlet a projectile shaped piercing
mandrel is held in position on the end of a water-cooled
mandrel support bar, located on the delivery side of the
mill. As the billet, which is in a plastic state, enters
the mill, the rolls grab it at opposite points on its
circumference. As the billet is drawn and compressed the
108
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109
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spreading of the metal sets up a lateral tension that may
cause its particles to be drawn away from the center. The
nose of the mandrel is at a point preceding the forming of
the cavity to insure a smooth inner surface. The pierced
billet is drawn out by the rolls and in passing over the
mandrel produces the hollow shell. The initial piercing
produces a hollow tube with a comparatively heavy wall. The
second piercing mill further reduces the wall thickness and
increases the diameter and length of the piece required in
producing large diameter product.
In the plug mill, a plug on a support bar is rammed into the
end of the shell. The shell is drawn over the plug by
revolving rolls, slightly reducing the wall thickness and
increasing the diameter and length. The rotary rolling mill
is used for large diameter pipe. Conical rolls grip and
spin the pipe, feeding it forward over a large tapered
mandrel, thereby affecting a decrease in the wall thickness
of the pipe and an increase in the diameter. The length of
the tube is substantially unchanged by this operation.
The reeling machine consists of rolls and a mandrel similar
to the piercing mill. A slight reduction in the thickness
of the wall is affected during the reeling operation. This
slight reduction has the effect of burnishing the inside and
outside surfaces of the tube and slightly increasing its
diameter. After reeling the tube is reheated and conveyed
to the sizing mill. The sizing mill consists of a series of
stands of sizing rolls, the grooves of which are slightly
smaller than the reeled tube. The diameter reduction
affected is to insure uniform size and roundness throughout
the length of the tube. After sizing the product is
straightened, end cropped, inspected, and finished as
required for its eventual use.
Electric-Resistance-Welded Tubing
Electric-resistance-welded tubing is referred to as ERW
tubing. Strip sheet or plate in coil form is used as a
starting material for ERW tubing. The steps used in the
manufacture of ERW tubing are: forming, welding, sizing,
cutting, and finishing.
Tubing is produced from single width strip, the width of
which will equal the perimeter of the tubing to be welded.
If extra wide strip is used it is passed through a slitting-
line for cutting to proper width and then recoiled. The
proper width strip is fed into forming rolls. The forming
rolls consist of an edge trimmer to smooth and clean the
edge of the strip for good welding and forming, closing and
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fin pass rolls. After the fin rolls the strip is in perfect
guidance to enter the welding section to provide the precise
circumference of the required tube. In the welding section
of the mill the tube is held in squeeze rolls at the correct
pressure to provide the desired weld as the edges are heated
at this point to welding temperature. The heat for welding
is provided by low-frequency power through electrode wheels
or radio-frequency power through sliding contacts or coil
induction. Typical power for welding is supplied at 450,000
cycles per second. The welded tube then passes under a
cutting tool which removes the flash resulting from the
pressure during welding. The welded seam or entire tube is
.then annealed or normalized depending on the required
metallurgy. After cooling the tube is sized on horizontal
and vertical sizing rolls to obtain a round finished product
of the desired diameter. After sizing the tube is cut to
length, straightened, and end finished if required. The
tubes are inspected and packed for shipment.
Electric-Welded Pipe
The electric-weld process or fusion weld is used to produce
pipe in unlimited diameters. If the circumference exceeds
the plate width, two or more plates may be welded together
to provide the necessary width. The steps required to make
plates into pipe by the electric-weld process are shearing,
planing, crimping, bending, welding, expanding, and
finishing.
Plate is transferred to the edge-planing machine where it is
aligned so that the two edges will be parallel and square
with the ends after planing. Forming plate into circular
pipe is usually performed in three operations called
crimping, "U"-ing, and "OM-ing. The first operation,
crimping, consists of bending the edges in a press so as to
avoid a flat surface near the longitudinal seam of the pipe.
The crimped plate is then conveyed to a "U"-ing machine. In
this operation the plate is centered over a series of
parallel rocker-type dies which lie along the axis of the
plate. A large "U"shaped die operated by a press, as long
as the longest length of plate, is moved down on the plate,
forcing it between the dies which automatically conform
themselves to the operation and assist in forming the plate
into the "U" shape. The plate is then transferred to what
is called the "O"-ing machine. The machine consists of two
semicircular dies which are as long as the plate. Rollers
mounted on vertical spindles prevent the plate from falling
and keep it in correct alignment as it enters the "O"-ing
machine. The "U"-shaped plate rests in the bottom die, and
the top die is forced down by a press, deforming the plate
112
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until it is the shape of an almost closed circle which is
then ready for welding. The pipe is held in position for
welding by a longitudinal rod which maintains the proper gap
for welding. A specially designed welding head deposits
flux along the joint, feeds metal electrode, and transmits
welding current to the joint and electrode. Molten filler
metal is deposited from the metal electrode to the work and
replaces the fluid flux and forms the weld. After the pipe
is welded on the outside it is welded on the inside by an
automatic welding machine mounted on the end of a long
cantilever arm and the pipe is drawn over this arm by a
carriage. After welding the scaly deposit left from the
flux is removed by a cantilevered tube device.
The final pipe diameter is obtained by either hydraulically
expanding the shell against a retaining jacket or
mechanically expanding it over an inside mandrel. In
hydraulic expansion, the ends are expanded to proper
diameter by mandrels. Retainer rings encircle the body of
the pipe which is filled with water and hydraulically
expanded to the limits of the bands. This also serves as a
hydraulic test. The expansion by either method sizes,
rounds, and straightens the pipe and provides a good test of
the weld. Attention is given to non-destructive inspection
of the weld quality, by x-ray examination of the weld. The
pipe is then placed in special machines which face the ends
to ensure they are smooth and at right angles. If the
joints are to be welded, the ends are beveled in this
operation prior to shipment.
More specific details of a typical ERW operation are also
presented in Figure 13-3.
Surface Preparation and Cleaning
Pickling
Correct surface preparation is the primary and most
important requirement for satisfactory application of
protective coatings to steel. Without a properly cleaned
surface, even the most expensive coatings will fail to
adhere or to prevent rusting of the steel base. A variety
of cleaning methods are utilized to insure good surface
preparation for subsequent coating. The steel surface must
also be cleaned at various stages during production to
insure that oxides formed on the surface are not worked into
the finished product causing marring, staining, or other
surface imperfections.
113
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Scale Removal
Heat is used in the production and finishing of steel.
Exposure to the atmosphere causes oxide scale to form on the
surface of the hot steel. This scale must be removed prior
to further processing. This operation can be done in one of
the following ways:
1. Acid Pickling
2. Mechanical Action
Pickling is the process of chemically removing oxides and
scale from the surface of the steel by the action of water
solutions of inorganic acids. While pickling is only one of
several methods of removing undesirable surface oxides, this
method is the most widely used in the manufacture of
finished steel products, due to comparatively low operating
cost and ease of operation.
Some products such as tubes and wire are pickled in batch
operations; that is, the product is immersed in an acid
solution and allowed to remain in this solution until the
scale or oxide film is removed. The material is lifted from
the bath, allowed to drain, and rinsed by sequential
immersion in rinse tanks.
Pickling lines for hot-rolled strip operate continuously on
coils that are welded together, passed through the pickler,
then sheared and recoiled. The steel passes through the
pickler countercurrently to the flow of the acid solution.
Most carbon steel is pickled with sulfuric or hydrochloric
acid; stainless steels are pickled with nitric, and
hydrofluoric acids. Various organic chemicals are used in
pickling to inhibit acid attack on the base metal, while
permitting preferential attack on the oxides; wetting agents
are used to improve the effective contact of the acid
solution with the metal surface. As in the batch operation
the steel passes from the pickling bath through a series of
rinse tanks.
Acid Pickling
The traditional method of scale removal is called
"pickling". Pickling is the chemical removal of surface
oxides (scale) from metal by immersion in a heated solution.
Carbon steel pickling is almost universally accomplished by
using either hydrochloric acid or sulfuric acid. The acid
conditions vary with the type material to be pickled. In
addition the bath temperature, use of inhibitors, and source
of agitation are also varied dependent on material to be
114
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pickled. Pickling is accomplished by either one or two
general processes dependent upon the type material to be
pickled.
A. Continuous Strip Pickling
Continuous strip pickling lines use principally horizontal
pickling tanks. (However, in a few cases, vertical spray
tanks are being employed.)
The fresh acid solution is added to the last tank section
and cascades through the tanks to an overflow located in the
first section. Acid solution flow is opposite the direction
of the strip travel. More specific details of the process
are shown on Figures 14-1 and 14-2.
B. Batch Type Pickling
Large, open tanks of a wide range of sizes are used for
batch type pickling, principally for rod coils, bars,
billets, sheet, strip, wire, and tubing. Pickling is also
applicable to many types of forgings, castings, structural
parts, and other sundry-shaped items. Tanks are generally
rubber lined and brick sheathed and hold a large volume of
heated acid solution. (Most often sulfuric acid is used.)
After a certain iron buildup due to scale removal
(pickling), the acid solution is considered spent and dumped
as a batch. A typical flow sheet illustrating details of
the process are shown on Figure 15.
There are three separate operations involved with the
pickling operation. They are as follows and directly
related to one another:
A. Pickling
B. Rinsing
C. Fume Scrubbing
Pickling
If pickling is to be done efficiently, it must be regarded
as what it really is...a chemical process, not merely a
method of cleaning, using hot acid. When this concept is
accepted, then the conditions necessary for any efficient
chemical reaction can be stated and defined. In pickling,
those conditions are temperature, agitation, and
concentration.
715
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Temperature. Temperature is critical because it
dramatically affects the rate of reaction. However, the
method of heating is also important. When live steam is
injected directly into the acid tank, it dilutes the acid
strength by increasing the volume of acid solution since the
steam condenses into water. To avoid dilution, internal or
external heat exchangers should be employed. These devices
transfer heat from steam to pickle liquor but allow the
condensate to be discharged externally.
Agitation. Agitation is probably the most ignored aid to
good pickling. The speed of pickling can be increased
significantly by properly agitating the acid pickle bath.
Sulfuric. A proven answer is an effective, custom-designed,
air-operated, agitation system suited to the type and
configuration of the steel being pickled. An added benefit
is that the evaporation (caused by air agitation)
concentrates, rather than dilutes, the acid bath. Induced
evaporation requires the addition of more pickling liquids
to maintain optimum tank level.
Hydrochloric. In the case of hydrochloric acid pickling
(which is usually the case in continuous strip pickling
lines) , the agitation can be achieved by recirculation of
the pickle liquor from the pickling tanks, into external
heat exchangers, and back into the pickling tanks. This
agitation is supplemented by the movement of the strip
itself through the pickling solution.
In either case, however, any additional vapors or acid mists
caused by the agitation system need not be a problem because
they can be collected in a proper exhaust system and
returned to the pickle tank for reuse.
Concentrations of acid and ferrous salts are related
directly to the rate of reaction and subsequently to the
rate of cleaning. Most pickling plants at this time do not
have facilities that would justify maintaining consistent
acid strengths. To reduce waste when pickle liquor is
dumped, the acid content is allowed to become weaker and
weaker, and thus the pickling process takes longer and
longer.
On the other hand, use of an acid recycling plant allows the
acid to be maintained consistently at its most effective
strength without the possibility of waste, because no acid
can leave the system.
119
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Rinse
The'rinse operation may vary from a one-step dunk to more
sophisticated multi-stage rinsing. The primary purpose of
the rinse is to remove contaminants prior to moving to the
next sequence in the process. The first rinse removes the
bulk of the contaminants from the pickled product.
The next rinse section can be of conventional nature, either
"dunk" rinse or spray. It removes the remainder of the
contaminants from the work. The water from this section is
used to replenish the first-stage rinse section.
The last stage of rinsing uses clean, fresh water as the
final washing medium to insure a clean product. This final
stage water is pumped to the previous stage rinse section.
Again, it may be possible to use the contaminated rinse
water as input water to the fume scrubber, prior to its
final disposition as pickle recycling system makeup water.
Most continuous strip pickling lines employ the traditional
approach to rinsing; flooding the strip with hundreds of
gallons of water per minute to wash away the few gallons of
acid that are dragged out of the pickling tanks. In the
past, this was a practical approach to the problem because
it effectively cleaned the strip and diluted the acid
content of the rinse water to an extremely low
concentration, for it was usually discharged without
treatment.
Instead of introducing a high volume flow of water into the
rinsing section and releasing it to the drain after one
contact with the strip, the multi-stage spray system
compartmentalizes the rinse water and reuses it over and
over. The net effect is that the amount of water impinging
upon the strip is actually greater than the amount in a
traditional spray-dunk system.
The dilution rate from one tank section to the next follows
a geometric progression, so the number of stages determines
how much clean water must be fed into the system to achieve
a given degree of cleanliness. For instance, a typical,
large, high-speed pickle line with a five-stage system could
operate at about 20 gpm.
Disposal of the rinse water at such a low rate of flow (and
with the higher acid concentration) becomes a relatively
simple matter. It can be further concentrated and piped to
the waste pickle liguor acid regeneration system or it may
120
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even be used as makeup for the solution in the pickling
tanks.
Multi-stage spray rinsing systems can easily be incorporated
into new continuous strip pickling lines, and they can be
installed in existing lines in place of the present rinsing
sections.
Fume Scrubbing
Acid fumes are prevalent in the pickling process and must be
removed in order to provide a good working environment.
Many existing exhaust systems discharge directly to the
atmosphere, causing, air pollution. To remove the acid from
the exhaust stream, washing or filtration methods may be
applied. In scrubbers, the acid droplets are contacted with
water, trapped, and then flushed away. This, however,
merely trades air pollution for water pollution because the
acid has contaminated the scrubber water.
Sulfuric. Acid mist filters use specially designed
synthetic fibers in a filter box which is installed in the
discharge end of an exhaust system. This unit releases
water vapor to the atmosphere while it collects the acid
droplets and returns them to the pickle tank. The acid mist
filter controls air pollution and simultaneously recovers
acid for reuse. No water is used in its operation;
therefore, no liquid effluent is discharged.
Hydrochloric. The wet-type scrubber works and, in most
cases, works well. Its biggest deterrence, however, is that
it usually requires and thereby contaminates large volumes
of water (typically, 50 to 200 gallons per minute). The
logical solution, therefore, is to (1) minimize the volume
of water used; (2) instead of fresh water use contaminated
water (such as rinse water) ; (3) use all of the scrubber
water as makeup water in the pickling operation, thereby
eliminating the discharge of acidified waters.
Solvents clean metal surfaces by dissolving and diluting
foreign matter such as oil, grease, soil, and drawing and
cutting compounds. Oil or grease may be removed by wiping
or scrubbing the surface with solvent and clean rags or
brushes. The steel may also be completely immersed in the
solvent, or solvent sprays may be used, or the steel may be
subject to vapor degreasing in equipment in which vaporized
solvent condenses on the surfaces to be cleaned. Solvents
used include mineral spirits, naphthenes, and some
chlorinated hydrocarbons.
121
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Mechanical Action
A second method for removal of unwanted matter from the
metal surface can be accomplished through mechanical action.
Pickling and mechanical action are not mutually exclusive
and are generally used in combination. However, further
disucssion of mechanical cleaning is not necessary since
mechanical cleaning operations do not produce waste waters.
Cold Rolling
Cold rolling is that operation where unheated metal is
passed through a pair of rolls for the purpose of reducing
its thickness, of producing a smooth dense surface and of
developing controlled mechanical properties in the metal.
Any one of a combination may be the reason for cold rolling
the material. Cold rolling generally implies a rolling
operation in which the thickness of the material is reduced
a relatively small amount to produce a superior surface or
impart the desired mechanical properties to the rolled
material.
Cold reduction is a special form of cold rolling in which
the thickness of the starting material is reduced by
relatively large amounts in each pass through the rolls. In
the production of most cold rolled materials, the cold
reduction process is used to reduce the thickness of the hot
rolled breakdown between 25% and 90X. After cleaning and
annealing, a large percentage of material is subject to a
cold rolling operation called tempering. In tempering, the
thickness of the material is reduced only a few percent to
impart the desired mechanical properties and surface
characteristics to the final product.
Cold rolled strip, cold rolled sheet, black plate and cold
rolled flat bar are the principal products from cold reduced
flat rolling mills. Carbon, alloy or stainless steel are
used depending on the end use of the products. The greatest
percentage of the products rolled are from carbon steel in
sheet form and are used as base material for such coated
products as long terne sheets, galvanized sheets, aluminum
coated sheets, tin-plate, or tin-free steel. Hot rolled
coils called "breakdowns" are the base material used in the
cold rolling operation. Prior to rolling, however, they
must be descaled and pickled, usually in a continuous
pickling operation.
There are several types of cold reduction mills varying in
design from single stand reversing mills to continuous mills
with up to six stands in tandem. In the single stand
122
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reversing mill, the product is rolled back and forth between
the work rolls until the desired thickness and
characteristics are reached. In the single stand non-
reversing mill the material makes a single pass through the
rolls and is recoiled. If additional rolling is required
the coil is returned to the head end of the mill and
reworked. The single stand non-reversing mill is generally
used for tempering operations.
The bulk of the cold reduced flat steel is rolled on
continuous three, four, or five stand tandem mills. In
these mills the material continually passes from roll to
roll, to be further reduced and leaves the final roll at the
desired thickness. The continuous rolling mills represent
modern technology and would be the type of equipment
installed in new mills.
A typical modern cold rolling shop would contain a
continuous pickling operation (sulfuric or hydrochloric
acid) for the removal of scale and rust from the hot rolled
breakdown coil. As it leaves the pickler the strip is oiled
to prevent rusting and to act as a lubricant in the cold
rolling mill. The coil is then fed into a continuous cold
rolling reducing mill that can contain up to six rolling
stands in tandem (in series) . Each stand contributes to the
reduction in thickness of the material; the first
contributing the greatest reduction while the last stand
acts as a straightening, finishing, and gauging roll.
Unlike hot forming, no scale is formed during this
operation.
During rolling the steel becomes quite hard and unsuitable
for most uses. As a result, the strip must usually undergo
an annealing operation to return its ductility and to effect
other changes in mechanical properties to render the
material suitable for its intended use. This is done in
either a batch or continuous annealing operation.
In batch or box annealing a large stationary mass of steel
is subject to a long heat treating cycle and allowed to
slowly cool. In continuous annealing a single strip of cold
reduced product passes through a furnace in a relatively
short period of time. The heat treating and cooling cycle
in the furnace is determined by the temperature gradient
within the furnace as well as the dimensions and rate of
travel of the steel. To prevent oxidation and the formation
of scale, inert atmospheres are maintained in these furnaces
at all times.
124
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Prior to annealing the material must be cleaned of all dirt
and oil from the pickler to prevent surface blemishes. In
the case of the continuous annealing furnaces the material
is uncoiled and passes through a continuous cleaning
operation prior to entering the furnace. On leaving the
furnace the material is oiled, recoiled, and is ready to be
tempered.
The temper mill is a single stand cold rolling mill whose
prime purpose is to produce a slight reduction in thickness
of the steel in order to develop the proper stiffness or
temper by cold working the steel at a controlled rate. The
end use of the material dictates the degree of tempering to
be performed.
An oil-water emulsion lubricant is sprayed on the material
prior to its entering the rolls of a cold rolling mill and
the material is coated with oil prior to recoiling. This
oil prevents rust while the material is in transit or in
storage and must be removed before the material can be
further processed or formed.
Cold reduced, flat rolled products are made by cold-rolling
pickled strip; the thickness is reduced 25% to 99% in this
operation and a smooth, dense surface is produced. The
product may be sold as cold reduced, but is usually heat
treated.
More specific details of the cold rolling process are
presented on Figure 16.
Coatings
The simplest, yet most useful definition of the term
"coating" is the application of a layer of one substance to
completely cover another. In the iron and steel industry,
coatings are applied for a variety of reasons. Most often,
a relatively thin layer of a metallic element such as tin,
zinc, chromium or aluminum is applied to carbon steel,
giving desirable qualities, such as resistance to corrosion,
safety from contamination, or decorative appearance, for a
fraction of the cost of product made from the coating metal
alone. The finished materials retain the strength of steel,
while gaining the high surface quality of the coating.
Figure 17 presents a schematic of the material transfer from
slab to the various coating processes.
There are many different types of coating materials in
addition to metallic elements. These include non-metals,
like oxides, sulfides, phosphates, and silicates; simple and
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complex organic compounds, like synthetic alkyd resins,
varnishes, and bituminous coatings; and miscellaneous
inorganic coatings, like vitreous enamel (a layer of glass
fused to a steel base); and metallic powders in silicate
paints. But the great bulk of coatings associated with the
iron and steel industry are the metallic coatings, so they
will be emphasized in the following discussions.
All methods for applying protective coatings to steel
surfaces require careful attention to proper surface prepar-
ation - the primary and most important step in the coating
process. Without such surface preparation, good adhesion of
the protective coating is impossible, and without good
adhesion, the coating can hardly be considered "protective."
The type of surface preparation will vary somewhat with the
nature of the coating to be applied, but it always aims at
cleanliness and uniformity of surface. Commonly used are
alkaline or solvent cleaning for grease removal; acid
pickling for removing scale or rust; and physical
desurfacing abrasives or brushes.
Following the preparation of suitable surfaces, metallic
coatings may be applied to those surfaces by one of the
following methods:
Hot Dip Process. The steel is immersed in a molten bath of
the coating metal, then removed from the bath in such a way
that the coating is uniformly distributed over the metal
surface as free of discontinuities as possible. Most zinc
coatings, and all aluminum and terne (a lead/tin alloy)
coatings are applied in this manner. In the past, tin was
also applied as a hot-dipped coating, but the electrolytic
tin plate process has almost completely supplanted this
practice.
Metal Spraying. The coating metal is drawn into wire, then
fed into a specially-built spray gun using compressed air
and a gaseous fuel. The wire is melted, and projected
against the steel surface being coated. The molten
particles cool quickly and adhere to the steel.
Metal Cementation. The coating metal is alloyed into the
surface of the base metal at elevated temperature and often
in a reducing atmosphere. The coated metal, when cool, may
be considered to be a solid solution of that metal in iron.
Fusion welding. Using an electrical current of sufficient
density, the surfaces of the coating metal and the steel
base metal are fused together.
127
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Metal Cladding. This process for coating steel is practiced
in any of several variations. In one method, the steel core
is mounted in a covered mold and heated in an inert
atmosphere to a temperature greater than the melting point
of the coating metal, which is then carefully cast about it
while the core remains in the mold. Cladding is also
accomplished by rolling flat steel, then placing it between
two sheets of the coating metal, not unlike a simple
sandwich. The stack is then cold rolled into one mass using
high pressures, or heated and hot rolled together to form a
tight bond between the coating metal and the steel core.
Another method of metal cladding ideally suited for wire
drawing consists of forcing a solid steel rod into a coating
metal tube of very slightly larger inside diameter. The
action of drawing this pair into wire results in a product
with a uniform metal coat around a steel core.
After application of the coating by one of the foregoing
methods, the coated product may still be subject to a wide
variety of treatment steps. It may be rinsed, dried and
oiled to improve handling and protect against oxidation of
the coating. It may require additional remelting to insure
smooth, even- deposition of the metallic coating. Or a
chemical treatment may be provided following the coating
operation to passivate the coated surface or to provide
certain desirable characteristics to enhance subsequent
processing steps. For example, galvanized (zinc-coated)
strip may be treated with zinc phosphate to produce a
surface with excellent paint-adhere nee properties. More
specific discussion of these processes is included in the
descriptions of the individual coating operations which
follows.
The principal metallic coating operations practiced in the
iron and steel industry can be divided into two major
classes, hot coating and cold coating. Zinc, terne, and
aluminum coatings are most often applied hot, while tin and
chromium are most often applied electro!ytically from
plating solutions maintained between 20-90°C (68-194°F), not
actually "cold," but relatively so when compared with molten
metal temperatures encountered in the hot dip processes.
Hot Coating
Hot dipped coating using baths of molten metal is practiced
in the iron and steel industry as a batch-dip operation for
sheet, plate, pipe or other pre-formed products, or on a
continuous basis using coiled strip as the base metal
source. Mill processes vary, depending on the coating being
applied.
128
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Zinc. The batch-dip operation normally follows hot rolling,
batch annealing, cold rolling, and pre-forming or cutting to
size. Rolling lubricants are removed by alkaline cleaning,
and final surface preparation requires acid pickling in
stationary tubs provided with slight agitation. Following
pickling, residual acid and iron salts are removed either
via an alkaline dip; thorough water rinsing; or prolonged
immersion in boiling water. The latter practice has the
added advantage of minimizing hydrogen embrittlement. Clean
base metal forms then are conveyed, by hand or via conveyor
belt, through the flux box section of the coating pot, and
immersed in the molten metal. Coated products are withdrawn
from the bath and subjected to drying with a warm air blast,
or chemical treatment with ammonium chloride, sulfur
dioxide, chromate or phosphate solutions to produce special
galvanized finishes and surface characteristics. A final
water rinse may be used, with subsequent drying, after which
the product is ready for shipment.
Continuous hot-dip galvanizing, which accounts for about 60%
of total galvanizing production, is practiced via several
different arrangements of processing steps. The simplest
version starts with annealed and tempered strip which
receives a light muriatic acid (HCl) pickle and rinse, then
proceeds directly through a layer of fluxing agent to the
molten zinc bath. The coated strip is dried and recoiled,
or cut to size for shipment. More elaborate continuous
galvanizing lines utilize additional stages leading up to
the hot-dip step. At least one plant incorporates a
sequence of pickling in hot sulfuric acid; rinsing and
scrubbing with brushes; a hot alkaline dip into a cleaning
solution; scrubbing in alkaline solutions; an electrolytic
hot alkaline cleaning step; rinsing and scrubbing with
brushes; a light pickle in hot sulfuric acid; rinsing and
scrubbing with brushes; a dip into a hot zinc sulfate flux
bath; the hot dip into molten zinc; dip and spray with
chromate or phosphate solutions; a final water rinse; drying
with hot air; and recoiling.
Other producers use a so-called "furnace line" to treat
their strip prior to coating with zinc. The incoming coils
are very hard following the cold reduction step unless a
separate annealing step is practiced. Furnace line
operators include this step in their continuous galvanizing
sequence, as follows. Cold rolled coils are given a hot
alkaline cleaning, rinsing, and scrubbing and a light
pickling in hot acid followed by water rinses. • Strip then
enters a controlled atmosphere heating chamber (annealing
furnace) up to 60 meters (200 ft) in length with a series of
independently controlled heat zones to provide temperatures
129
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required for annealing, yet sufficient cooling so that strip
exits the furnace at temperatures slightly above the molten
bath temperature. A mixture of NX gas (principally
nitrogen, with controlled amounts of methane, carbon
monoxide, and carbon dioxide) and cracked ammonia is used in
some annealing furnaces to prevent oxidation and
decarburization during the treatment process. The exit end
of the furnace discharges strip below the surface of the
molten zinc bath. A sinker roll submerged near the surface
of the molten zinc, is used for controlling the thickness
and distribution of the coating. Forced air blasts are used
to cool the exiting strip and to help solidify the zinc
coating. A dip or spray chromate or phosphate chemical
treatment may be provided at this point to retard formation
of white corrosion products on the coating. A final rinse
and drying step may also follow. Finished coated strip is
recoiled or cut to sizes ready for shipment.
Another type of furnace line subjects cold rolled strip to a
complex furnace gas containing hydrogen chloride. After
annealing and cooling, a light pickling in hydrochloric acid
is done immediately prior to entering the flux section of a
conventional molten zinc pot. In place of the usual exit
rolls for controlling coating thickness, asbestos wipes are
used to yield very thin, but extremely adherent zinc
coatings.
More specific details of the hot coating operations are
shown on Figures 18, 19, and 20.
Terne Metal. Terne (from a French word meaning "dull") is
an inexpensive, corrosion-resistant hot-dipped coating
consisting of lead and tin in a ratio typically near four to
one. Lead alone does not alloy with iron, but does form a
solid solution with tin, which in turn alloys readily with
iron, although requiring higher temperatures than for tin
alone.
A major portion of all terne coated material is used in the
auto industry to manufacture gasoline tanks, with lesser
amounts going into the production of automotive mufflers,
oil pans, air cleaners, and radiator parts. Other end
products made of terne metal include roofing materials,
portable fire extinguishers, and burial caskets.
As in the case of hot-dipped galvanizing, batch and
continuous terne coating operations both exist, although the
continuous process is used to produce by far the larger
portion of the market. Both metals used in terne coating
are very corrosion resistant, as is their combination. But
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since both lead and tin are cathodic to iron in most
environments, corrosion is actually accelerated if any
portion of the base metal is exposed. For this reason,
terne coatings are usually thicker than other metallic
coatings, and for maximum corrosion resistance, even the
thickest terne coatings benefit from painting or other
protective finishing.
The batch-dip terne coating operation normally is performed
on cold reduced, batch annealed, and temper rolled coils cut
into sheets. Oils and greases are removed via alkaline or
solvent (mineral spirits) cleaning, and final surface
preparation requires an HCl dip just prior to coating.
Excess acid is sgueezed from the sheets by rubber rolls, and
the sheets are conveyed through a flux box containing a hot
solution of zinc chloride in hydrochloric acid, or a molten
zinc chloride salt bath, to remove any residual iron oxides,
and leave a dry steel surface. The sheets are then passed
downward through a molten terne metal bath maintained at
325° to 360°C (617° to 680°F), where the coating is applied,
then upward through an oil bath floating atop the terne pot.
This oil tends to maintain the high temperature long enough
for oil rolls to control deposition and coating thickness
evenly over the sheet surfaces. Although most batch-dipped
terne coatings utilize a single unit as described above, a
wider range of coating weights sometimes necessitates a pass
through a second unit of the same type, but including
another oil bath instead of the zinc chloride flux box prior
to application of the second coat.
The steel strip fed to a continuous terne coating operation
receives the same preliminary treatment as the steel
processed on the batch-dip line, except that it remains in
the coil form, and the cleaning procedure prior to pickling
is most often done electrolytically. The normal sequence is
oil and grease removal in an electrolytic alkaline unit;
rinsing and scrubbing with brushes; pickling; terne coating;
and oiling via a bath similar to batch dipping. After
cooling, residual oils are removed in a branner, which
consists of tandem sets of cleaning rolls made of thousands
of tightly compressed flannel discs. Middlings from grain
milling, called bran, are fed to the first set of rolls to
absorb moisture and excess oil, while the remaining rolls
distribute a light oil film evenly over the entire coated
surface. The final product is then recoiled, or cut to
sizes for shipment as terne coated flats. More specific
details of the terne line are shown on Figure 21.
Combination Acid Pickling
135
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Alloy and Stainless Steel Pickling
The production of stainless steel strip typically proceeds
as follows:
Hot-rolled strip (0.125"), annealed, and pickled in two 35-
foot long tanks containing 15 percent hydrochloric acid at
160°F, followed by a single similar tank containing U
percent hydrofluoric acid and 10 percent nitric acid at 150-
170°F.
The production of stainless steel billets, bars, and plates
typically involves a single pickling operation in a 10
percent sulfuric acid solution at 140°-160°F, followed by a
10 percent HNO3, 4 percent HF bath at 130°-150°F.
The alloy steels, depending upon the grade, are pickled in a
great variety of acids and combinations of acids. Various
combinations of sulfuric, hydrochloric, nitric, and
phosphoric acids are used.
More specific details of combination acid pickling
operations are shown on Figure 22.
Scale Removal
Kolene Process
The Kolene process utilizes highly oxidizing salt baths at a
temperature of 700-900°F. These salts react far more
aggressively with scale than with the base metal. The
typical treatment cycle consists of Kolene treatment, water
quenching, water rinsing, acid dipping, and water rinsing.
More specific details of the Kolene scale removal process
are shown on Figure 23.
Hydride Process
Sodium hydride descaling depends upon the strong reducing
properties of sodium hydride carried at 1.5 to 2 percent by
weight in a fused caustic soda bath at 700°F. Most scale-
forming oxides are reduced to the base metal; oxides of
metals that form acid radicals are partly reduced. The
hydride is formed in place by the reaction of hydrogen and
metallic sodium in open bottom chambers partially immersed
in the bath. Most commercial installations use dissolved
ammonia as a source of hydrogen. The typical treatment
cycle consists of sodium hydride treatment, water quenching,
water rinsing, acid dipping, and water rinsing.
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More specific details of the hydride scale removal process
are shown on Figure 24.
Wire Pickling and Coating
Wire Drawi ng
The size limits for wire range to under 1 inch for round
sections and to approximately 1/2 inch for square sections.
Larger rounds and squares and all hexagonal and octagonal
shapes are commonly known as bars. The slender rods or bars
from which wire is drawn are produced by hot rolling. Wire
rods are produced in coils from the rolling mills and
constitute the raw material for the wire mills.
The rod is prepared for drawing by one of several types of
heat treatment: patenting, annealing, or normalizing.
Patenting is a term peculiar to the wire industry and
consists of heating to a point well above the upper critical
temperature and then rapidly cooling to a predetermined
temperature at which the desired microstructure and
mechanical properties are attained. Heating is achieved in
an open flame, a muffle furnace, or a hot lead bath and
cooling is achieved in either the open air or a low-
temperature lead bath. Annealing is accomplished by
controlled-atmosphere, salt-bath or continuous lead
annealing. In controlled-atmosphere annealing, heating is
accomplished in a furnace in which oxygen is excluded by an
inert gas. Salt-bath annealing is accomplished by immersing
coiled wire in molten salt baths and continuous lead
annealing is accomplished by drawing the wire through a
molten lead bath. Normalizing is the general process of
reheating steel above its critical temperature and air
cooling.
Following heat treatment, the wire is cleaned by batch
pickling, rinsed, and coated. The coating is usually lime
or borax which protects the surface of the cleaned rod and
acts as a carrier for the lubricant used in conventional
drawing. After the coating is applied, the rod is baked to
dryness. "Wet" drawing refers to the application of copper
plating to the wire to act as a drawing lubricant.
Wire drawing equipment consist essentially of the power
driven "block" which pulls the rod through the "die", and
the die which is made of tungsten carbide or diamond.
Diamond dies are used for very fine sizes of high-carbon and
aHoy-steel wire. The heat generated in drawing is
dissipated by either air or water cooling of the blocks and
by water-cooled dies. Wire for cold heating or cold forging
140
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is one of the major uses for alloy and stainless steel wire
from which bolts, rivet pins, and screws are made.
Stainless steel wire is also used for non-magnetic armature-
binding wire, welding rods, spring wire, weaving wires for
sifters and high-temperature conveyor belts, and wire rope
for specialized uses.
More specific details of wire pickling and coating
operations are shown in Figure 25.
Continuous Alkaline Cleaning
Alkaline Cleaners
Alkaline cleaners are used where mineral and animal fats and
oils must be removed. Mere dipping in solutions of various
compositions, concentrations, and temperatures is often
satisfactory. The use of electrolytic cleaning may be
advisable for large scale production, or where this method
yields a cleaner product. Caustic soda, soda ash, alkaline
silicates and phosphates are common alkaline cleaning
agents. Sometimes the addition of wetting agents to the
cleaning bath will facilitate cleaning.
More specific deatils of continuous alkaline cleaning
operations are shown on Figure 26.
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SECTION IV
INDUSTRY SUBCATEGORIZATION
With respect to identifying any relevant, discrete
subcategories for the iron and steel industry, the following
factors were considered in determining industry
subcategories for the purpose of the application of effluent
limitation guidelines and standards of performance:
1. Manufacturing processes and equipment
2. Products
3. Raw materials
4. Wastewater characteristics
5. Waste treatability
6. Gas cleaning equipment
7. Size and age
8. Land availability (location)
9. Process water usage
After considering all of these factors, it was concluded
that the iron and steel industry is comprised of separate
and distinct processes with enough variability in product
and waste to require categorizing into a number of discrete
subcategories. The individual processes, products, and the
wastewater characteristics comprise the most significant
factors in the categorization of this most complex industry.
The remaining factors served to support and substantiate the
basic subcategorization. Waste treatability proved to be
most significant in substantiating the subcategories. From
this evaluation it was determined that fourteen
subcategories would be required for the purposes of
developing effluent limitations for the hot forming and cold
finishing segments of the Iron and Steel Industry. These
subcategories are as follows:
G. Basic Oxygen Furnace — A melting operation which
involves the use of high purity oxygen supplied at high
pressures to the furnace.
K. Vacuum Degassing — A melting operation which further
refines the steel by subjecting the steel in the ladle
to a high vacuum in an enclosed refractory lined
chamber.
L. Continuous Casting and Pressure Slab Molding — A
melting operation producing billets, blooms and slabs by
casting these forms directly from the hot steel thus
eliminating primary rolling, ingots, soaking pits, mold
145
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preparation and stripping facilities. Pressure slab
molding involves the direct casting of a slab shape in a
mold.
M. Hot Forming Primary — An operation which involves
reduction of hot steel ingots into slabs and blooms by
rolling and associated processes.
N. Hot Forming Section — An operation which involves
reduction of hot blooms into various shapes and sizes of
products such as billets, bars, rods and sections.
O. Hot Forming Flat — An operation which involves the
reduction of hot slabs into plates, strips and sheet
steel or skelp.
P. Pipe and Tubes — An operation which uses heated
steel to produce welded or seamless pipe or tube.
Q. Pickling-Sulfuric Acid — An operation involving the
immersion of rods, wire or similar steel product in a
sulfuric acid bath and subseguent rinsing.
R. Pickling-Hydrochloric Acid-Batch and Continuous — An
operation involving immersion of rods, wires or similar
steel product, with continuous product flow, in a
hydrochloric acid bath with rinsing, and associated
absorber vent and fume hood scrubbers.
S. Cold Rolling — An operation involving the size
reduction and improvement in surface or mechanical
properties of unheated steel with associated rolling and
cooling oils and solutions.
T. Hot Coat-Galvanizing — An operation involving the
immersion of steel in a bath of molten zinc and
associated processes.
U. Hot Coat-Terne -- An operation involving the
immersion of steel in a bath of molten lead and tin and
associated processes.
V. Miscellaneous Runoffs — Runoff from coal, limestone
and ore storage piles and discharges from casting and
slagging operations.
W. Combination Acid Pickling (Batch and Continuous) , —
An operation involving the immersion of alloy and
stainless steel in a combination of hydrofluoric and
nitric and other acids.
146
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X. Scale Removal (Kolene and Hydride); -An operation
involving scale removal using salt baths at a
temperature of 700-900°F.
,Y. Wire Pickling and Coating — An operation which
involves the pickling and coating of alloy and stainless
wire prior to further drawing operations.
Z. Continuous Alkaline Cleaning -An operation which
involves the electrolytic alkaline cleaning of strip and
wire.
Rationale for Categorization - Factors Considered
Manufacturing Processes
The inherent manufacturing or production processes
associated with the production of a diversity of steel
products served as a principal basis for defining
subcategories. This factor was particularly important in
establishing initial broad segmentation into hot forming,
cold finishing and "non-production" groupings and
subsequently into more specific subcategories. For example,
the processes and methods associated with hot steel working
differ inherently from those for cold rolling.
Hot working of steel involves the deformation of steel at
elevated temperatures (2150°F to 2450°F) whereas the cold
finishing processes are carried out at far lower
temperatures (less than 1000°F).
Hot forming operations require relatively large pieces of
machinery and auxiliary equipment (large rollers, runout
tables, steel handling equipment) in the shaping of the
large steel ingots into blooms, slabs and billets ( some
ingots are over 300 tons). Generally cold finishing
processes do not require the large equipment when finishing
the much smaller steel sizes (less than a ton of steel for
some finishing operations).
Although hot forming and cold rolling operations both shape
steel, hot rolling is only suitable to a fairly large guage.
At a smaller gauge cold working processes may be used, which
at the same time as reducing the cross section area can also
impact certain surface characteristics. For example, steel
can be rolled down to .08" in thickness in a hot strip mill,
but to reach a tin mill gauge such as .008 in the steel must
be cold rolled, possibly several times.
147
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Similarly, the processes of surface preparation by chemicals
(pickling) or surface coating (galvanizing) do not
incorporate any of the principal forming or shaping
operations. Moreover, the surface preparation operations
themselves differ substantially in that, for example,
pickling by sulfuric, hydrochloric or nitric-hydrofluoric
acid immersion involve discretely different practices from
those related to coating the steel with zinc or tin/lead
alloys.
Pickling processes clean the metal surface by the use of
chemical means (acid) while coating operations coat the
surface of the steel with another metal in order to impart
surface characteristics, such as corrosion resistance (See
below under Final Products). Pickling and coating processes
may be either batch type or continuous.
Coating operations use a variety of metals as raw coating
materials. For example, tin plate and galvanized steel
generally have a chromium coating over the tin or zinc.
Alloy steel wire may be coated with copper.
Those ancillary operations which are involved in the overall
production process differ in function from those described
above. Areas used for (open) bulk storage of coal,
limestone or iron ore involve none of the specific steel
making functions. Similarly, equipment and machinery
maintenance facilities carry out an additional separate set
of activities. As would be expected, there is a close
interrelationship between the production processes (and the
subcategories derived therefrom) and the factors of final
products, raw materials used, and raw wastewater
characteristics and treatability as described below.
Final Products
Consideration of the type of nature of final products helped
refine the definition of those subcategories where
manufacturing takes place; however, this consideration was
not relevant to the miscellaneous runoff subcategory. In
addition to the more clearly defined final product
differences, e.g., hot formed (unfinished) steel versus
galvanized finished product, this factor was useful in
substantiating subcategories where discrete differences were
less apparent. Another consideration was that of product
surface area. The surface area of the product being hot
rolled affects the rate at which contact cooling and
flushing water must be applied, and thus the quantity and
quality of the wastewater generated (see waste water
characteri sites and treatability). The relative poor
148
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surface condition of the product to be rolled during the hot
forming processes also affects the load of mill scale that
will be generated when contact process water is applied.
Available data revealed that certain hot forming mills
(designated primary mills) produced only the larger sized
bloom or slab pieces of steel; other mills produced billets,
rods or like products (section mills) or plates, strips or
sheet steel (flat mills) . An additional group of mills were
further defined by their output of steel pipe and tube
products.
Furthermore the difference in final products in relation to
coating and finishing operations suggested additional basis
for subcategorization. Generally all coated products are
pickled prior to the coating application, however, not all
pickled products are coated. As would be expected
consideration of final products complements the basis for
subcategorization according to manufacturing processes.
Final product analysis augments the basis for
subcategorization by raw materials in relation to the
pickling and coating operations. Specific selection of
pickling acid is made when definite final product surface or
appearance characteristics are desired. Likewise when
certain product coating reguirements are needed (for
corrosion resistance) the use of raw materials are
differentiated. Also, the particular pickling acid used is
dependent on the type of steel being pickled.
Raw Materials
Raw materials helped to support subcategorization. This
factor is intended to incorporate both the characteristic
nature of the steel inputs to the subcategories, as well as
the intermediate raw materials employed in each subcategory,
e.g., acids, coatings and the like.
Hot forming operations use a limited source of steel inputs.
Primary blooming and slabbing mills use large bulky ingots
(some over 300 tons) as their only raw material. Products
with a well defined cross-section area such as billets,
rails, beams, bars are formed from hot blooms which are of
certain cross-sectional area (at least 6x6) themselves.
Hot slabs are the base material for the production of
plates, strips and sheet steel or skelp. Hot rolled skelp
is used in the production welded tubular products.
Production of seamless tubular products use solid round bars
or billets as their source of raw material. The
149
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consideration of raw material steel inputs into the hot
forming processes further substantiates the use of the
manufacturing processes as a basis for subcategorization.
The intermediate raw materials employed in each subcategory
strengthens the applicability of subcategorization.
Pickling processes may use different types of raw materials
(i.e. sulfuric, nitric - hydrofluoric or hydrochloric acid)
to produce the desired results. Coating operations employ
different coating raw materials to impact the desired
coating. For example, molten zinc is the primary raw
material in hot coat galvanizing whereas molten lead and tin
are the raw materials for the hot coat-terne operations.
Analysis of raw materials used in the forming and finishing
of steel substantiate the basis of subcategorization when
differentiating similar production processes, i.e. acid
pickling and coatings.
Wastewater Characteristics and Treatability
While there are many inherent similarities in raw wastewater
characteristics and treatability between subcategories,
there are also significant differences. As a consequence,
this factor was very important in supporting the defined
subcategorization.
Analysis of the available data indicates the presence of
certain pollutants in waste water from particular
manufacturing operations. As a consequence, the wastewater
characteristics further substantiate the subcategorization
scheme.
Tin, lead, chromium, copper and zinc are predominently
characteristic wastewater constituents of coating operations
(due to raw materials) and not typically present in hot
forming, rolling or pickling processes and consequently they
are not found in the wastewater from these operations.
Furthermore, investigation of wastewater characteristics
together with raw material considerations substantiates the
basis for the coating subcategories. The presence of lead
in terne coating operations serves as another basis for
differentiating terne coating from galvanized coatings and
also differentiates terne coating from all other coating
subcategorie s.
The data also reveals that oil and grease are characteristic
wastewater constituents of hot forming and cold rolling
processes. Analysis of the available information does not
support subcategorization on the basis of the various types
of oil and grease found in either the manufacturing process
150
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itself or in the process wastewater. However, this analysis
also indicates that the oil and grease levels in pickling
and coating wastewaters (without commingling with cold
rolling wastes) are significantly smaller then those levels
found in the hot forming and cold rolling operations. This
strongly suggests a basis for subcategorization according to
wastewater characteristics.
Continuing with the wastewater analysis, comparisons of
suspended solids characteristics and levels of concentration
revealed that the suspended solids from the hot forming
operations are comparatively larger in size, are heavier,
and are more easily removed from the wastewater than those
solids produced in the non hot-forming operations. Even
within the various hot forming operations, the particle size
of the suspended solids varies. The relatively good surface
conditions of the product to be rolled during the hot
forming - section step, compared to the surface quality
available during previous primary rolling steps, usually
results in the generation of lesser quantities of mill scale
than in primary rolling steps. The particle size will be
generally smaller and consequently more difficult to settle
out than scale from previous steps. Therefore, treatability
factors complement the manufactuing process basis for sub-
categorization.
Gas Cleaning Equipment
Certain manufacturing operations (steelmaking, pickling and
hot coatings) require the use of wet gas cleaning equipment.
The pungency and corrosive nature of acid vapors from
pickling operations require the use of fume hood scrubbers
or similar types of equipment. Since gas cleaning equipment
is a unique mechanism for vapor control, those operations
producing vapors are differentiated from other manufacturing
operations and from other methods of treatability.
Size and Age
Industry size and age are not viable factors for
subcategorization of the iron and steel industry.
Information compiled during this study and previous iron and
steel industry investigations do not reveal any discernable
relationship between these factors and raw waste loads,
effluent quality, treatability, or any other basis for
subcategorization.
Size was considered as a plausible factor for subcategoriza-
tion but from analysis of the compiled data size does not
justify subcategorization. Throughout the iron and steel
151
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industry mills vary greatly in physical size, layout and
product size. However, these considerations revealed no
relationship to process water usage, discharge rate effluent
quality or any other pertinent factors.
Age as a factor might be expected to be at least amenable to
quantitative identification and interpretation, but the
extensive investigation of the industry does not indicate
that age alone is a factor. The iron and steel industry is
old. Some of the old mills have incorporated early
operating ideas and practices. However, other old mills are
very new in that they have incorporated the latest operating
ideas and practices.
Nevertheless, most older mills have been updated by internal
changes in process, design, and equipment. Therefore, to
say that a mill was built 50 years ago and is 50 years old
is not particularly meaningful in terms of interpreting mill
practices. In addition, no consistent pattern between mill
age and raw waste characteristics was found.
Tables 9 through 25 provide, in addition to the plant size,
the geographic location of the plant together with the age
of the plant and the age of the treatment facility.
Land Availability (location)
Examination of the raw waste characteristics, process water
application rates, discharge rates, effluent quality and
pertinent factors relative to plant location reveals no
general relationship or pattern.
Process Water Usage
Examination of the available data indicates that within well
defined ranges process water usage can be directly
correlated to the various manufacturing operations. This
correlation varifies the basis of the subcategorization
scheme by manufacturing processes. Differences in scale
(see size factor) of a categorized manufacturing process was
considered. The results indicated that on a per ton of
steel basis, process water usage is not dependent upon the
scale or largeness of the manufacturing operation. It was
observed though that much larger volumes of process cooling
water are generally required to cool the hot forming
machinery than that which is needed for the cold forming
operations, thus further substantiating the
subcategorization by manufacturing process.
152
-------
Considerations of age, location and raw materials revealed
no discernable differences in process water usage. Process
water usage parallels the subcategorization by final product
considerations (see final products factor) where data
revealed that for particular product requirements well
defined manufacturing processes must be employed.
153
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SECTION V
WATER USE AND WASTE CHARACTERIZATION
GENERAL
The wastewater streams for the industry are described
individually in their respective subcategories. Waste loads
were developed by actual plant sampling programs. Raw waste
loads are defined as the contaminants attributable to the
process of concern. Process wastewater is defined as that
water which comes into intimate contact with the process,
product, raw materials, by-products, etc., thus becoming
contaminated with various pollutants characteristic of the
process itself. Non-contact cooling water is defined as
that water which does not directly contact processes,
products, raw materials, by-products, etc. Non-process
cooling water is defined as that water which is used for
non-process operations, i.e., utilities, maintenance
department cooling water.
Steel Making Operations
The steelmaking process produces fume, smoke, and waste
gases as the unwanted impurities are burned off and the
process vaporizes or entrains a portion of the molten steel
into the off-gases. Wastewater results from the steelmaking
processes when wet collection systems are used on the
furnaces. Spray cooling, quenching, or the use of wet
washers result in waste waters containing particulates from
the gas stream. Dry collection methods such as the use of
waste heat boilers, evaporation chambers, and spark boxes do
not produce waste water effluents.
BASIC OXYGEN FURNACE OPERATION
General process and flow diagrams are contained in the Phase
I Development Document and the reader is referred to the
information contained therein. Only one furnace, a basic
oxygen furnace, was sampled in the alloy and stainless steel
industry. All other furnaces, including electric furnaces,
used dry air pollution control methods or none. There are
reportedly only two furnaces with wet air pollution controls
in the alloy sector of the steel industry, as contrasted to
larger numbers in the carbon steel sector. The effluent
characteristics for this subcategory are estimated from the
plant survey data which indicate that the scrubber effluent
from a B.O.F. producing alloy steel averages 872 gals/ton
containing 19.2 Ibs/ton of suspended solids, the solids
173
-------
TABLE 26
Characteristics of
Basic Oxygen Furnace (Wet A1r Pollution
Control Methods) Plant Wastes
Plant Raw Waste Loads
Characteristics Plants
Flow, 1/kkg 3,639
Suspended Solids, mg/1 2,628
Fluoride 9.5
TABLE 27
Characteristics of
Vacuum Degassing Plant Wastes
Plant Raw Waste Loads
Characteristics Plants
Flow, 1/kkg 4,983 3,021
Suspended Solids, kg/kkg 0.881 0.030
Fluoride, kg/kkg 0.160
Manganese, kg/kkg 0.171
174
-------
loading varying by factors of 0.2 to 1.8 over 3 days of
sampling. The carbon steel plant survey data showed
effluent volumes of 130-1020 gals/ton and suspended solids
loads of 0.35 - 19.1 Ibs/ton. Table 26 summarizes the net
plant raw waste loads for the plants studied. Raw waste
loads are presented only for the critical parameters which
include fluoride and suspended solids.
VACUUM DEGASSING
Vacuum degassing for the carbon steel sector was covered in
the Phase I development document. It is suggested that the
reader refer to that for more detailed information
concerning the process.
The barometric condenser cooling water system is direct
process contact cooling where the water is used to condense
the steam ejector exhausted steam and gases that are emitted
from the molten steel. The vacuum produced in the degassing
operation is by means of multi-stage steam jet ejectors pro-
ducing pressure down to 0.064 atmosphere. The degassing
operation removes hydrogen, carbon and oxygen as carbon mon-
oxide plus any volatile alloys in the steel and some iron
oxide particulate.
Table 27 summarizes the net plant raw waste loads for the
plants studied. Raw waste loads are presented only for the
critical parameters which include lead, nitrate, manganese,
suspended solids, and zinc.
Vacuum degassing operations surveyed included a facility
using water once-through on the ejectors, a facility using
completely recirculated water on the ejectors, and a
facility using a mechanical vacuum system.
CONTINUOUS CASTING AND PRESSURE SLAB MOLDING
Again, the reader is referred to the Phase I Development for
more detailed information.
Table 28 summarizes the net plant raw waste loads for the
plants studied. Raw waste loads are presented only for the
critical parameters which include oil and suspended solids.
HOT FORMING OPERATIONS
Wastewater results from the hot forming operation because of
the large amount of direct contact cooling and descaling
waters required between the hot steel and the rolling mill
equipment. Approximately 4% of the water sprayed on the hot
175
-------
TABLE 28
Characteristics of
Continuous Casting and Pressure
Slab Molding Plant Wastes
Plant Raw Waste Loads
Characteristics
Flow, gaj/ton
Suspended Solids mg/1
Fluoride
Oil and Grease
pH Units
Plants
D
15
Q
B
126
24.5
16.3
8.9
2,435
0.002
44.8
7.6
TABLE 29
Characteristics of
Hot Forming Primary Plant Wastes
Plant Raw Waste Loads
Characteristics
Flow, 1/kkg
Suspended Solids, mg/1
Oil and Grease, mg/1
Plants
A-2
2,890
86
13.9
B-2
2,131
57
150
C-2
3,248
21
2
D-2
L-2
3,732 2,560
91 11
5.1 4.3
176
-------
steel evaporates and the balance is discharged beneath the
rolling mill equipment to trenches called flumes.
When the hot steel product is being rolled, iron oxide scale
keeps forming on the surface of the hot steel and this scale
is continuously removed by direct contact high pressure
(1,000-2,000 psig) spray water before each roll pass of the
product. Low pressure spray cooling water is also used to
keep the mill stand and table rolls cool as the hot steel
passes over or in between them.
The wastewaters from descaling and mill equipment cooling
are generally discharged via flumes or trenches to inground
concrete settling chambers called scale pits where the
heavier iron oxide particles are settled out. These scale
pits generally contain underflow weirs with launders to trap
oils and greases picked up by the cooling waters. The waste
oils are removed from the water surfaces by belt, rope, or
other type of floating oil skimmers, and pumped to large
capacity waste oil storage tanks where contract haulers
periodically remove the accumulated oils. The scale is
cleaned out by mechanical means such as clam shell buckets,
drag link conveyors, etc.
The wastewaters discharged from scale pits are either
discharged to plant sewers or are recycled back to the
mills. The suspended solids content in overflows is
generally 100 to 200 mg/1, but these wastewaters can be
further treated by means of filtration or thickeners with
chemical coagulation.
Due to the many different types of hydraulic and lubrication
systems required to maintain the rolling mill equipment, the
direct contact cooling and descaling waters pick up oil and
greases when being sprayed over the mill equipment. Also,
water soluble oil solutions are sometimes used for mill roll
spray coolant waters.
When automatic hot scarfing machines are used for the final
surface finishing of the blooms or slabs, fume, smoke, and
slag is produced.
The scarfing operation on hot steel results in a continuous
production of molten slag ahead of the reaction zone. This
slag is directed and driven to a slag pit or trench beneath
the scarfer machine and water is used to break-up and flush
the slag being generated by the scarfing process. Water is
also used to spray exposed equipment items in the vicinity
of the scarfing reaction to protect them from heat and
flying slag particles. High pressure water (150 psig) is
177
-------
used for flushing the slag from the steel surface while
psig) low pressure water is used for the spray cooling
water.
The wastewaters from the automatic scarfer spray water
systems are generally routed into a scale pit where the
heavy slag particles are settled out and the overflow waters
discharged to the plant sewers. Often these spray waters
are discharged into the same primary scale pit as the mill
equipment cooling and descaling waters.
The hot scarfing process also results in appreciable
quantities of fume and smoke, the quantity and density
depending upon steel analysis, scarfing oxygen pressure, and
efficiency of the slag water jets. The smoke contains some
solids in addition to steam and gases. The solids are
mainly oxides of iron with traces of alloying elements found
in the scarfed steel. The oxides are submicron in size and,
therefore, it is necessary to collect this smoke and
discharge outside of the mill building by means of a
suitable exhaust system. Wastewater results when wet type
dust collectors are used to contain and clean the exhaust
gases from the scarfer. Dry collectors are not normally
used due to the saturated nature of the exhaust gases.
HOT FORMING - PRIMARY
Blooming and Slabbing Mills
General process and water flow schematic of typical blooming
and slabbing mills are presented on Figure 10.
The blooming and slabbing mills have generally four main
plant water systems.
a. Descaling water sprays
b. Table roll cooling sprays
c. Scarfer water spray system
d. Mill stand cooling sprays
All the water cooling and descaling systems are generally a
once-through water system discharged into a scale pit where
the scale is settled out, oil is trapped by means of weirs
and the overflow water is pumped to a sewer. Some mills do
not have scale pits but use mechanical means such as drag
scrapers or clam buckets for the scale removal while the
water is collected in a sump and pumped to a central plant
water treatment system.
178
-------
TABLE 29-A
Characteristics of
Hot Forming Primary Plant Wastes
Pl-ant Raw Waste Loads
Specialty Steel
Characteristics
Flow gal/ton
Suspended Solids mg/1
Oil and Grease mg/1
pH Units
Plants
Characteristics
Flow, 1/kkg
Suspended Solids, mg/1
Oil and Grease, mg/1
Flow, 1/kkg
Suspended Solids, mg/1
Oil and Grease, mg/1
E H
2,741 2,479 5
1 86 158
26 1.6
7.2 5.4
TABLE 30
K R
,600 4,780
81
2.9
7
M D Q
4,494 535 3,420
52 161 47
8.7 58.9 4.3
6.5 4.1 7.3
Characteristics of
Hot Forming Section Plant Wastes
Plant Raw Waste Loads
A-2 D-2-a
2,485 51,891
/I 86 38
14 11
E-2-b F*2
13,198 9,312
/I 29 12
5 0
Plants
D-2-b
51,258
20
11
G-2
16,859
21
0.4
D-2-c E-2-a
35,045 36,796
33 71
13 14
H-2 1-2
28,969 20,904
33 125
14 1.4
179
-------
TABLE 30-A
Characteristics of
Hot Forming - Section - Plant Wastes
Plant Raw Waste Loads
Specialty Steel
Characteristics
Flow, gal/ton
Suspended Solids, mg/1
Oil and Grease
pH Units
Plants
R 0
7,965 12,857
26.5 78
0.66 0
7.1
1,781
30
1.2
7.5
M C
935 5,269
54 31
9.9 1
6.5 5.1
TABLE 30A(Cont'd)
Characteristics
Flow, gal/ton
Suspended Solids, mg/1
Oil and Grease
pH Units
Plants
H
4,210
40
5.6
6.1
1,469
63
3.5
7.4
0
4,697
11
4.5
8.4
180
-------
The wet. collecting systems used for the scarfing fume are
generally recycle systems with a system blowdown to maintain
cycles of concentration. The system's blowdown is generally
pumped backed to the mill scale pit.
Tables 29 and 29A summarize the plant raw waste loads for
the plants studied.
HOT FORMING - SECTION
General process and water flow schematic of,a typical mill
is presented on Figures 11.
Section mills generally have water systems similar to
primary mills as discussed above. The wastewaters produced
are primarily the result of reheat furnace noncontact
cooling waters, mill equipment cooling waters, and high
pressure spray water descaling systems. The furnace cooling
waters are generally once-through and discharged to plant
sewers.
The mill equipment cooling and high pressure descaling
waters are discharged via flumes and trenches to scale pits
where the heavier solids are settled out. Oils and greases
picked up by the cooling waters are trapped in the scale
pits by means of underflow weirs and launders.
The oils are removed from the surface of scale pit waters by
means of belt, rope or floating type oil skimmers, and
pumped to large capacity oil storage tanks where contract
haulers periodically remove the accumulated oils. The scale
pit overflow waters are generally discharged to plant
sewers, but sometimes recycled back to the mills as sluicing
or flushing waters in flumes and trenches. Some mills use
mechanical scraper or drag line buckets to remove the
heavier iron oxide scale beneath the mill stands and stock
pile the scale for recycling in mills. The waters are still
flushed into scale pits or settling chambers for final
sedimentation and skimming of waste oils and greases.
Thickeners with chemical coagulation or filtration can be
used to further treat the scale pit overflow waters and
reduce the suspended solids from 100-200 mg/1 to 25 mg/1.
Tables 30 and 30-A summarize the plant raw waste loads for
the plants studied.
HOT FORMING - FLAT
181
-------
General process and water flow schematic of typical plate
and hot strip mills are presented on Figure 12.
Plate Mills
The plate mills have generally four types of mill water
systems.
a. Descaling water sprays - Direct Contact
b. Table roll and plate cooling water sprays - Direct
Contact
c. Mill stand roll cooling sprays - Direct Contact
d. Reheat slat furnace skid cooling water - Noncontact
The slab reheat furnace noncontact cooling waters can either
be once-through or recycled water systems depending upon
mill water availability. Flows up to 315 I/sec (5,000 gpm)
are required to cool the furnace skids but discharged waters
are noncontact cooling and will only pick up heat. The
descaling sprays, table roll, and plate cooling sprays and
mill stand rolling coding sprays are generally once-through
systems where the waters are discharged to flumes or sumps
beneath the plate mill stands. The scale and oil-bearing
waters are flushed into scale pits where the majority (up to
90%) of scale is settled out, oil is removed by means of
weirs and skimmers and scale pit overflow water is dis-
charged to sewers. Removal of scale is generally through
mechanical means such as cranes with clam buckets or drag
scraper conveyors beneath the mill stands.
Hot Strip Mills
The hot strip mills have generally five types of mill water
systems:
a. Slab reheat furnace cooling water - Noncontact
b. High pressure descaling water - Direct Contact
c. Low pressure roll coolant water - Direct Contact
d. Table roll and shear cooling waters - Direct Contact
e. Strip spray cooling waters - Direct Contact
The slab reheat furnace noncontact cooling waters descaling
sprays, shearing cooling, scale and oil-bearing waters are
as described above for plate mills.
The strip spray cooling waters are sprayed to cool the strip
after it has been rolled on the final mill finishing stands.
This water system may be once-through if good guality water
is available, but because of the great quantities required,
(up to 4,400 I/sec [70,000 gpm] on new hot strip mills)
182
-------
TABLE 31
Characteristics of
Hot Forming Flat Plant Wastes
Plant Raw Waste Loads
Characteristics
Flow, 1/KKg
Suspended
Solids, mg/1
Oil and
Grease, mg/1
J-2
32,142
16
5
K-2
23,073
57
4.3
Plants
L-2
34,215
11
4.3
M-2
35,182
25
2
N-2
30,328
14
10
TABLE 31-A
Characteristics of
Hot Forming Flat Plant Wastes
Plant Raw Waste Loads
Specialty Steel
Characteristics
Flow, gal/ton
Suspended Solids, mg/1
Oil and Grease
pH Units
Plants
E
6,773
23
13.6
6.0
F
12,878
85
50.9
6.5
D
3,314
23
10.9
3.7
183
-------
recycle systems are installed. Approximately 856 of the
strip coolinq waters evaporate and the balance is either
discharged to sewers or recycled. The suspended solids in
overflow waters is generally 100 to 200 mg/1.
Tables 31 and 31-A summarize the plant raw waste load for
the plants studied.
PIPE AND TUBE MILLS
General process and water flow schematic of pipe and tube
mills are presented on Figure 13.
As previously described, the pipe and tube mills can be
classed into three types of hot forming production methods:
Butt welded pipe; Electric-resistance welded tubing; and
Seamless tubes.
The butt welded pipe mills generally have three types of
water systems.
1. Noncontact cooling waters in skelp heating furnaces -
water cooled skids, water cooled welding bell, etc.
2. Roll cooling spray waters
3. Pipe cooling bed water bosh
The skelp heating furnace noncontact cooling waters can
either be once-through or recycled water systems depending
upon mill water availability. The effluent waters are
noncontact cooling waters and will only increase in heat
content.
The roll cooling spray waters are generally once-through
water systems where the scale and oil-bearing waters are
discharged to flumes or trenches beneath the pipe mill roll
stands and in turn flushed into scale pits where scale is
settled out and oils removed by means of weirs and skimmers.
Removal of scale is generally through mechanical means such
as drag scraper conveyors, clam tuckets hung on overhead
cranes, etc. About H% of the spray waters evaporate and the
balance is discharged to the scale pits.
The pipe cooling bed water bosh is sometimes used to provide
adequate cooling capacity without excessively long pipe
cooling beds. The waters are generally once-through systems
providing direct control cooling and waters are discharged
into the roll cooling water systems.
184
-------
TABLE 32
Characteristics of
Pipe and Tubes - hot Worked Plant Wastes
Plant Raw Waste Loads
Characteristics Plants
E-2 GG-2 II-2 JJ-2 KK-2
Flow, 1/KKg 53,255* 7,089 15,371* 9,562* 2,148
Suspended Solids, mg/1 27 40 50 103 61
Oil and Grease, mg/1 1 7 0 6-3
*Includes non-contact cooling water flows.
TABLE 33
Characteristics of
Pipe and Tube - Cold Worked Plant Wastes
Plant Raw Waste Loads
Characteristics Plants
HH-2
Flow, 1/KKg 24,019
Suspended Solids, mg/1 19
Oil and Grease, mg/1 61
TABLE 34
Characteristics of
Pickling - Sulfuric Acid - Batch Plant Wastes
Plant Raw Waste Loads from Spent Pickle Liquor
Characteristics Plants
1-2 0-2 P-2 Q-2 R-2 S-2
Flow, 1/KKg 151 104 60 101 23 132
Dissolved Iron, % N/A 8.6 6.2 8.0 6.8 N/A
Suspended Solids, mg/1 N/A 48 260 N/A 70 N/A
185
-------
The electric-resistance welded tubing mills have only two
types of water systems.
1. Noncontact cooling water for equipment welders, etc.
2. Water soluble oil spray cooling systems
Electric-resistance welded tubing is formed by cold rolling
and then is heated by the electric welder as the tube seam
is welded. The tube is cooled by passing through a spray of
water soluble oils. These waters ai;e generally recycle
systems and makeup is required.
The seamless tube mills generally have three types of water
systems:
1. Noncontact cooling waters - reheat furnaces, water
cooled, piercing mandrels, etc.
2. Roll spray coolant waters
3. Spray water quench
The noncontact cooling waters for furnaces or piercing (tube
shaping) mandrels can either be once-through or recycled
depending upon mill water availability. The noncontact
effluent waters will only increase in temperature.
The roll spray coolant waters are generally once-through
systems where the spray water is discharged to scale pits
via flumes and trenches beneath the tube mill stands. Scale
is settled out and oil is trapped and removed by means of
weirs and skimmers.
The spray quench water system is used to produce higher
strength tubes than just hot working the tubing. The tubing
is quenched, reheated, and quenched by means of water
sprays. These waters are once-through systems.
Tables 32 and 33 summarize the plant raw waste loads for the
plants studied.
PICKLING
General process and water flow schematics of the continuous
and batch pickling operations are presented on Figures 14
and 15, The primary function of a pickling facility is to
chemically remove iron scale from steel. The amount of iron
removed depends upon the type of steel being pickled and the
specific condition of the product. As an example, heavy and
bulky steel shapes, such as billets, bars, etc., may
186
-------
experience an iron weight loss (due to pickling) of 1/456.
This would amount to 5 Ib Fe loss per ton being pickled.
Steel strip or sheet is more typically 1/2% (10 Ib Fe per
ton'pickled) . Rod (for manufacture of wire) ranges from
1/2% to 2% (10 Ib to HO Ib per ton) . The three major
wastewater sources associated with pickling are inseparable
from the process. They include:
Spent Pickle Liquor. The pickling solution becomes pro-
gressively saturated with ferrous salts. When the
ferrous salt content reaches a certain level, the acid
becomes ineffective and has to be dumped.
Rinse Water. Rinse water is pickle liquor in dilute
form. Disposal of large quantities of rinse water poses
a difficult and serious problem.
Acid Vapors and Mists. The emission of pungent and
corrosive mist and vapor from the pickling tanks
presents serious hazards, both indoors from a health and
maintenance standpoint and outdoors as air pollution.
In addition to the free acid and ferrous salt content, the
spent liquor could also contain relatively small amounts of
other metal sulfates, chlorides, lubricants, inhibitors,
hydrocarbons, and other impurities.
SPENT PICKLE LIQUOR
Sulfuric Acid. Typical spent sulfuric pickle liquor
averages about 8% free acid and 8% dissolved iron (Fe). A
gallon of this spent acid solution weighs about 10 Ib.
On this basis, each ton of steel pickled (at IX loss) would
generate about 25 gal. of spent pickle liquor.
Therefore, assuming 16,000,000 tons of steel pickled
annually with sulfuric, the yearly volume of spent sulfuric
pickle liquor would be 400,000,000 gal. This volume would
contain about 320,000,000 Ib of free sulfuric acid and
essentially the same amount of dissolved iron (as I
-------
Therefore, assuming 40,000,000 tons of steel pickled
annually with hydrochloric, the yearly volume of spent
hydrochloric pickle liquor would be 800,000,000 gal. This
volume would contain about 80,000,000 lb of free
hydrochloric acid and 800,000,000 lb of dissolved iron (as
Fe) . This amount of iron would appear as about
1,800,000,000 lb of ferrous chloride (or 900,000 tons of
FeCl.2) .
RINSE WATERS
After pickling is achieved in the acid bath, the material is
subjected to a water rinse to remove the acid/iron solution
prior to further processing. The traditional method of
rinsing calls for high volumes of fresh water simply to wash
the pickled product by flushing. Pickling facilities vary;
however, typical rinse water volumes range from 1.5 to 65
I/sec (25 to 1,000 gal./minute) flow rate. The larger
continuous strip pickling lines use 6 to 65 I/sec (100 to
1,000 gpm), most often closer to 20-25 I/sec (300-400 gpm).
Batch type pickling facilities average about 1.5-20 I/sec
(25 to 300 gpm).
ACID VAPORS ANC MISTS
All pickling facilities, large or small, continuous or
batch, produce acid vapors or mists at the pickling tank.
If the tank itself is not equipped with a means of
collecting and transporting these emissions away from the
pickling line, an indoor health and maintenance problem
occurs. If the tank is so equipped and the acid emissions
are properly withdrawn from the line, the vapors and mists
are transferred outdoors and may create a serious air
pollution problem.
Many pickling facilities are properly equipped to include a
scrubbing device which uses water to collect the acid mist.
This then transfers the air pollution problem into a water
pollution problem.
Studies by some steel mills indicate that about 10% to 15%
of the acid from a pickling line is lost in the rinse water
(as dragout) and in the fume exhaust system.
Tables 34-41 summarize the plant raw waste loads for the
plants studied.
COLD ROLLING OPERATIONS
188
-------
TABLE 34-A
Characteristics of
Pic.kling - Su If uric Acid - Batch - Plant Wastes
Plant Raw Waste Loads
Specialty Steel
Characteristics Plants
Flow, gal/ton 30
Suspended Solids, mg/1 162
Oil and Grease, mg/1 1.3
Dissolved Iron, mg/1 8,991
pH Units 1.6
189
-------
TABLE 34-1
Characteristics of
Pickling - Sulfuric Acid - Continuous Plant Wastes
Raw Waste Loads from Spent Pickle Liquor
Concentrate
Characteristics Plants
Flow, 1/kkg
Suspended solids, mg/1
Dissolved iron, %
Raw
Flow, 1/kkg
Suspended solids
Dissolved iron,
Waste
, mg/1
mg/1
H-2
61
180
4
Load
477
27
43
Raw Waste Load
Flow, 1/kkg
Suspended solids
Dissolved iron,
, mg/1
mg/1
T-2
61
65
.8 3.4
QQ-2
99
186
4
SS-2
40
200
.8 4.8
TT-2
100
222
7.1
WW-2
188
91
1.9
from Rinsing Operation
90
49
1833
from Fume
696
35
65
Hood
8
2
26
840
96
63
Scrubbers
.3 84
.5 27.5
.2 0.43
560
1.5
80.5
10
221
88
1182
6
355
TABLE 35
Characteristics of
Pickling - Sulfuric Acid - Batch Plant Wastes
Plant Raw Waste Loads from Rinsing Operations
Characteristics Plants
1-2 0-2 P-2 Q-2 R-2 S-2
(a) (b)
Flow, 1/KKg 872 1935 N/A 70 33 151 826
Dissolved Iron, mg/1 380 33 46,000 7,500 4,700 460 2,600
Suspended Solids, mg/1 70 21 18 155 20 2,100 1,720
190
-------
TABLE 36
Characteristics of
Pickling - Hydrochloric Acid - Batch Plant Wastes
Plant Raw Waste Load from Spent Pickle Liquor
Characteristics Plants
U-2 V-2
Flow, 1/KKg 27 17
Dissolved Iron, % 7.7 10.7
Suspended Solids, mg/1 N/A N/A
TABLE 37
Characteristics of
Pickling - Hydrochloric Acid - Batch Plant Wastes
Plant Raw Waste Load from Rinsing Operations
Characteristics Plants
U-2 V-2
Flow, 1/KKg 387 696
Dissolved Iron, mg/1 190 270
Suspended Solids, mg/1 0 0
191
-------
TABLE 38
Characteristics of
Pickling - Hydrochloric Acid - Continuous Plant Wastes
Plant Raw Waste Loads from Spent Pickle Liquor
Characteristics
Flow, 1/KKg
Dissolved Iron, %
Suspended Solids, mg/1
1-2
151
N/A
N/A
W-2
50
13.5
88
Plants
X-2
39
N/A
N/A
Y-2
67
N/A
N/A
Z-2
173
N/A
N/A
AA-2
13.6
11.6
120
TABLE 39
Characteristics of
Pickling - Hydrochloric Acid - Continuous Plant Wastes
Plant Raw Waste Load from Regeneration
Absorber Exhaust Scrubber
Characteristics
Flow, 1/KKg
Dissolved Iron, mg/1
Suspended Solids, mg/1
W-2
411
70
132
Plants
X-2
1184
64
70
Y-2
1288
61
85
192
-------
TABLE 40
Characteristics of
Pickling - Hydrochloric Acid - Continuous Plant Wastes
Plant Raw Waste Loads from Rinsing Operations
Characteristics Plants
1-2 W-2 X-2* Y-2 Z-2 AA-2 BB-2*
Flow, 1/KKg 917 949 1,972 209 519 24.4 664
Dissolved Iron, mg/1 7 136 220 437 N/A 14,000 1,750
Suspended Solids, mg/1 53 20 12 7 N/A 20 52
*Includes flow from fume hood scrubbers
TABLE 41
Characteristics of
Pickling - Hydrochloric Acid - Continuous Plant Wastes
Plant Raw Waste Loads from Fume Hood Scrubbers
Characteristics Plants
W-2 Y-2
Flow, 1/KKg 190 174
Dissolved Iron, mg/1 24 4
Suspended Solids, mg/1 4 7
193
-------
General process and water flow schematic of a typical cold
rolling operation is presented on Figure 16.
The major water use on cold reduction mills is for cooling
the rolls and the material being rolled. This is
accomplished by using a flooded lubrication system to supply
both lubrication and cooling. A water-oil emulsion is
sprayed directly on the material and rolls as the material
enters the rolls. Each stand has its own sprays and where
recycle is used, its own recycle system. Past practice has
been the direct sewering of the emulsion. However, the high
cost of rolling oils and the expense of complying with
pollution control regulations are modifying this practice,
and recycle and recovery systems are currently in common
use.
The water used in a cold rolling mill must be a fairly good
quality water, free of suspended matter. High quality
rolling oils are added to form the emulsion. Since the
material being rolled is clean and free from rust, and since
no scale is generated during the rolling, oil and
temperature are the basic pollutants in this discharge.
Those mills still using once-through solution systems have
installed oil recovery plants. The recovered oil is
returned for processing or otherwise disposed of. Those
mills operating recirculation systems on all mill stands
have no continuous discharge of wastewaters. However, means
must be provided for the treatment or disposal of batch
discharges of spent rolling solutions. The majority of
plants operate as combinations of bath systems, and will
have significant volumes of continuously running
wa st ewat er s.
Regardless of what systems are used, miscellaneous oil leaks
and spills can occur. One area associated with the cold
rolling operation but separate from the rolling mill itself
is the maintenance and roll finishing shop. Oil-bearing
wastewater originating in these areas is a major contributor
to wastewater discharges from a cold rolling mill using
total recirculation on all stands. Oil and water leaks in
the oil basement also contribute heavily to this problem.
Considerable heat is generated during heavy reductions at
high speed on the various types of mills. Not only is the
temperature of the product raised but also the temperature
of the rolls. This heat is removed from the mill via a
flooded lubrication system. A water-oil emulsion is sprayed
on the material as it enters the rolls. This emulsion
drains off between stands and each stand has its own spray
194
-------
TABLE 42
Characteristics of
Cold Rolling Plant Wastes
Plant Raw Waste Loads
Characteristics Plants
X-2 BB-2 DD-2 EE-2 FF-2
Flow, 1/KKg 74 1,268 1,647 73 759
Suspended Solids, mg/1 90 N/A 952 637 194
Oil 41,136 54 1,399 1,180 354
TABLE 42-A
Characteristics of
Cold Rolling Plant Wastes
Plant Raw Waste Loads
Characteristics Plants
D I P
Flow, gal/ton 57 — 52,920
Suspended Solids, mg/1 1,744 — —
Oil and Grease, mg/1 3,697 36,000 465
Iron, mg/1 — — —
195
-------
system. In the older mills this emulsion was used once and
sewered without any treatment.
Modern continuous cold reduction mills recycle the oil
emulsion in the flooded lubrication system. Each stand has
its own collection tank and pump to return the emulsion to
the sprays. A five stand tandem mill would have five
recycle systems, one for each stand. With this arrangement,
it is possible to renew one tank of emulsion at a time, or
all at once. It is also possible to use different oil
emulsions in each tank if the product being rolled so
requires. Mills using these recycle systems have no direct
discharge to the sewer. However, they do have the problem
of disposal of large batch dumps of spent rolling emulsions.
Mills using once-through systems usually install treatment
plants and palm oil recovery systems to reclaim these oils
for reprocessing and reuse. In this process various
techniques are used to break the eirulsion to separate the
oil from the water. The water is discharged while the oil
is returned to a processor for upgrading and resale. The
cost of palm oil and the treatment cost for its recovery
brought about the development of the recycle system.
The high cost of rolling oil has discouraged mills from
using the once-through system, hence it is the oil cost and
not pollution control that dictates the type of system to be
installed in mills. The recycle system eliminates the
continuous discharge of oil emulsions from cold rolling
mills.
Tables 42 and 42-A summarize the plant raw waste loads for
the plants studied.
All of the specialty steel cold reduction mills surveyed
recirculate the roll coolant solutions.
HOT COATING OPERATIONS
Wastewaters generated by the various hot coating techniques
practiced in the iron and steel industry fall into three
categories:
1. Continuously running rinse waters, which may include
rinses following alkaline and acid cleaning operations;
rinses following chemical treatment and surface passivation
operations; final rinses; and running wastewater flows from
fume scrubbing systems associated with air pollution control
devices.
196
-------
2. Intermittent discharges, which may include spent baths
from alkaline and acid cleaning operations; flux baths;
chemical treatment solutions; and ion exchange regenerant
solutions. The plating baths are normally not discharged as
wastewater, being either recovered or regenerated as part of
the coating operations, or sold to outside contractors for
processing and recovery.
3. Noncontact cooling waters associated with the hot
coating processes may include furnace cooling water and
molten metal pot cooling water.
General process and water flow schematics of typical
galvanizing lines are presented on Figure 17.
Galvanizing
General process and water flow schematics of typical
galvanizing lines are presented on Figures 18-20.
The continuously running rinse waters generated in
galvanizing may include alkaline cleaning rinses; sulfuric
or hydrochloric acid rinses; and chromate or phosphate
treatment final rinses. Combined total flow rates may range
from 10 to 150 I/sec (158-2,380 gpm) , depending upon whether
the noncontact cooling waters are included or not. The
wastewaters may contain suspended and dissolved matter,
sulfates, chlorides, phosphates, silicates, zinc, chromium,
and oily matter in concentrations ranging from traces to
high levels, depending on galvanizing line operating
conditions. Intermittent overflows of concentrated alkaline
or acid cleaning solutions and flux tank solutions may
occur, contributing to the load normally running
continuously. These can be minimized by close attention to
maintenance and operating conditions and through provision
of dragout recovery units where possible. Spent pickle
liquor is normally collected separately for disposal or
treatment. Typical noncontact cooling water sources from
galvanizing lines include zinc pot cooling and, from the so-
called "furnace lines," indirect furnace cooling waters.
Table 43 summarizes the net plant raw waste loads for the
plants studied.
Terne Coating
General process and water flow schematics of a typical terne
line operation are presented on Figure 21.
197
-------
TABLE 43
Characteristics of
Hot Coatings - Galvanizing Plant Wastes
Plant Raw Waste Loads
Characteristics
Flow, 1/KKg
Suspended Solids, mg/1
Oil & Grease, mg/1
Zinc, mg/1
Chromium, mg/1
Hexavalent Chromium, mg/1
Plants
1-2
V-2
917 19,500
94
15
N/A
N/A
N/A
16
5
N/A
N/A
N/A
MM-2
,239 E
88
48
0.2
4.5
0.003
NN-2
5,024
104
20
145
1.
8
0.011
TABLE 44
Characteristics of
Hot Coatings - Terne Plate Plant Wastes
Plant Raw Waste Loads
Characteristics
Flow, 1/kkg
Suspended Solids, mg/1
Oil & Grease, mg/1
Lead, mg/1
Tin, mg/1
00-2
,152
48
73
0.20
2.0
Plants
Rinses
4,116
PP-2
40
5
<0.05
<2
Fume Hood
5,946
9
0
<0.05
<2
198
-------
The continuously running rinses from the terne coating
operation may include rinses following immersion in alkaline
or mineral spirit degreasing solutions; and sulfuric or
hydrochloric acid rinses. Total flows may range from 10 to
60 I/sec (158-950 gpm) , depending upon whether the
noncontact cooling waters are included or not. This
wastewater may contain suspended and dissolved matter, oily
matter, sulfates, chlorides, iron, lead, and tin in
concentrations which depend on line operating conditions.
Intermittent discharges are limited to dragout or spills
from cleaning and pickling tanks. Spent pickle liquors are
normally collected separately for disposal or treatment.
The noncontact cooling water originates due to the necessity
for continuously cooling the molten terne pot.
Table HH summarizes the net plant raw waste loads for the
plants studied.
MISCELLANEOUS RUNOFFS
Miscellaneous runoffs may be defined as the flow of
wastewater that emanates from material storage or auxiliary
operations associated with a basic steel process.
Generally, the wastewater flow is intermittent but may
contain color, solids or other pollutants. The items
included in this category are generally associated with the
coke, iron, and steelmaking operations as follows:
1. Ingot Casting
2. Pig Casting
3. Coal Pile
U. Ore Pile
5. Stone Pi le
6. Slagging
Ingot Casting
Generally, the only water usage associated with ingot
casting is the spray cooling of the ingot molds in the mold
preparation and cleaning area. The hot molds are sprayed
with water to cool them, and at the same time knock off
minor amounts of scale adhering to the mold surfaces. The
majority of the water used is evaporated upon contacting the
hot mold. Any excess spray water, which is usually very
minor, falls to the ground, where it generally evaporates or
permeates into the ground.
The excess spray water contacting the ground is generally so
minor that there is rarely, if ever, sufficient volume to
cause an overland runoff from the area. If a runoff problem
199
-------
were to exis-t from excessive spraying of the moldsr any
potential pollution problems, which would be confined to
suspended scale particles, could be better resolved by
tightening up on spray water usage rather than by providing
treatment for the runoff.
Pig Casting
The lime wash used to coat the molds may create a
housekeeping problem around the pig machine. Small volumes
of water are used to wash down the area and to clean the
spray equipment. Water is also required to cool the pigs.
This water also washes off the surplus lime from the molds.
As in the case of ingot casting, excess spray water is so
minimal that there is rarely sufficient volume to run off
from an area. Excess spray water falls to the ground where
it either evaporates or permeates into the ground. Since
lime is used as a mold release agent in the pig casting
process, this minor excess water may be slightly alkaline.
However, the excess water is of such small volume and
alkalinity so slight, that the pollution potential of this
stream is usually negligible.
Some plants may divert this runoff to a small basin which is
periodically cleaned out. However, due to the small volume
of water and the intermittent nature of the pig operation,
there is no overflow from this pit. Where significant
runoffs occur, they could best be handled by tightening up
on spray water usage.
Raw Material Storage Piles
Large quantities of raw materials are required to operate
blast furnaces and integrated steel mills. As a general
rule, a minimum of six months supply is kept on hand at all
times. This will vary according to the plant location and
the source of the raw material. Huge piles of coal, iron
ore, and limestone will be observed next to the coke plant
and blast furnaces. The raw materials to operate these
plants are taken from these piles.
Coal Pile
Coal is delivered to the plant by barge, rail or truck. The
newly-delivered coal is scattered uniformly on the coal pile
and is compacted by running a bulldozer over the freshly
stored coal. This is done to reduce the amount of air
trapped in the coal pile to prevent spontaneous combustion
from taking place and igniting the coal pile. In some
200
-------
instances, a sealant is used on the exposed coal to minimize
windage losses from the storage pile.
These storage piles are generally at grade level. However,
some mills utilize concrete pits for raw material storage.
Sewers are never intentionally located in these storage
yards due to the problem of keeping them open. As a result,
storm water tends to collect in pools at the base of the
pile and under extreme drainage conditions, will overflow
and seek the nearest sewer. As a rule, this water
percolates through the storage pile into the ground and
there is not normally a visible runoff.
Coal storage piles at large steel mills are generally
located near a waterway adjacent to the wharf or dock where
the coal is unloaded. These piles vary in size, depending
upon the capacity of the blast furnace facilities, which
determines the load on the by-product coke ovens and the
amount of reserve supply kept on hand.
Because of the proximity of the coal storage piles to the
waterway, rainfall runoff from these piles may discharge to
the river. In addition, rainfall permeating through the
pile may percolate into the ground and eventually seep back
into the waterway.
Depending upon exposed surface area, rainfall intensity and
duration, runoff or permeability coefficients, and the
quality of the coal, the quantity and character of the
runoff and seepage discharges may vary considerably.
Generally, however, direct pile runoff during periods of
heavy rainfall would be contaminated with suspended coal
particles, with associated color and turbidity. Indirect
pile runoff, that runoff that seeps through the pile and
lags the surface runoff, may be more highly contaminated.
As the rainfall seeps through the pile, it is in extended
contact with the coal. This seepage will generally collect
at the bottom of the pile and will either provide a residual
surface runoff that continues after the rainfall has ceased,
or seep into the ground.
Because of the extended contact of this rainwater with the
coal, it may pick up significant contamination within the
pile from leaching or chemical reactions that may occur. In
addition to solids, this seepage may pick up heavy metals or
other dissolvable components within the coal. In addition,
if the particular coal stored contains significant fractions
of iron pyrites, the seepage will become fairly acidic from
exothermic wet and dry oxidation reactions that occur with
201
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TABLE 45
CHARACTERISTICS OF MISCELLANEOUS RUNOFFS -
COAL STORAGE PILES AND BLAST FURNACE SLAGGING WASTES
NET PLANT RAW WASTELOADS
Characteristics
Flow, 1/kkg
Ammonia, mg/1
BOD5, mg/1
Cyanide, Total, mg/1
pH, Units
Phenol, mg/1
Solvent Extractable Matter,
Hexane, mg/1
Sulfide, mg/1
Sulfite, mg/1
Suspended Matter, mg/1
Coal Storage
Pile
Plant C
0
2.20
15
3.23
7.6
0.57
8.0
<0.02
412
Blast Furnace
Slagging
Plant M
0
11.5
68.4
499
1,560
2
202
-------
these pyrites in the pile. These reactions are equivalent
to those that produce acid mine drainage from coal mines.
Samples taken of coal pile runoff from the base of a coal
pile after rainfall had ceased at an actual plant site
(Plant C) are shown in Table 45.
The high COD value measured from this sample is probably due
to the high concentration of suspended coal fines. The BODJ5
does not correlate with the COD in magnitude since the BOD5
test would not produce any significant biochemical reaction
with the suspended coal.
Because of the limited sampling that was possible during the
study, it is not practical to specifically characterize all
of the constituents that might appear in the runoff. Also,
these constituents would vary depending upon the factors
discussed above.
Iron Ore and Limestone
Iron ore and limestone are generally delivered by rail and
truck. The newly-delivered material is scattered across the
top of the storage pile to provide uniform mixing with the
materials already in the pile. These piles are at grade
level or in concrete pits and no intentional effort is made
to sewer the area. Normal storm runoff will accumulate at
the base of the pile and percolate into the ground water
table. There is normally no visible runoff into the local
sewer.
Ore Pile Runoff
Based upon the character of ores in general, the predominant
constituent of contaminated runoff from an ore pile would be
suspended solids, consisting mainly of iron oxides and
silica. As in the case of coal piles, the guality and
quantity of these runoffs and the presence of other
constituents would depend on the many variable factors
outlined above.
Stone Pile Runoff
However, it might be expected that runoff from these piles
would contain primarily suspended solids in the form of
calcium carbonate and some alkalinity. Again, their quality
and quantity would depend on variable factors previously
outlined.
203
-------
Slagging
For all of the steelmaking processes and the ironmaking
operation, slag is always generated. The molten slag is
usually deposited into ladles from the furnaces. These
ladles are transported'to a slag dump where the slag is
allowed to air cool or is sprayed with water. The slag is
then transported to a slag processing plant where the steel
scrap is reclaimed and the slag crushed into a saleable
product. The waste products from this process are generally
airborne dust and become waterborne when wet dust collecting
systems are added. When open hearth slag is wetted,
hydrogen sulfide will be emitted due to sulfur content of
slag.
Hot blast furnace slag is usually dumped into a large pit,
and quenched and cooled to a temperature at which it can be
transported relatively safely to a final disposal site or a
slag processing plant.
During quenching of the slag, there is little or no actual
runoff from the site, the great majority of the water being
evaporated. As the slag temperature is lowered, however,
some excess quench water will remain unevaporated. The
quench pits are normally graded so that this excess water
will collect in the bottom of the pit rather than run off
overland from the site. Once the cooled slag is removed for
final disposal, the pooled water laying in the bottom of the
quench pit will remain and be flashed off by the next hot
slag charge.
However, during this period of slag cooling, some of the
excess quench water may permeate into the ground, thus
constituting a subsurface discharge.
Samples of pooled quench water after contact with the slag
are shown in Table 45.
Although the actual amounts of undesirable contaminants
permeating into the ground is highly variable, depending
upon the amount of excess quench water used, the time of
contact between slag and pooled water and the general soil
permeability at the quench site, certain conditions might
produce undesirable subsurface discharges.
These potentially undesirable discharges could be controlled
or even eliminated if these quench pits were to have an
impermeable lining such as concrete or other suitable
material. Excess quench waters would then remain in the
quench pit until such time as they are evaporated by the
204
-------
next hot slag charge. In fact, concrete-lined slag pits do
exist at some plants where the slag quench station is in the
immediate vicinity of the blast furnace. This is done in
order to prevent soil removal during quench pit cleaning and
possible weakening of the blast furnace foundation.
Table 15 summarizes the raw waste loads for the
miscellaneous runoff sites studied.
COMBINATION ACID PICKLING OPERATIONS
General process and water flow schematics of a typical
combination acid pickling operation are presented on Figure
22.
Although the basic processes are similar to those for
sulfuric and hydrochloric acid, the type of steel (usually
stainless) dictates a nitric-hydrofluoric, or nitric acid
pickle liquor be used, since stainless steel is relatively
difficult to pickle. This may be used in conjunction with a
more conventional sulfuric or hydrochloric acid bath.
Continuous Combination Acid Pickling
The stainless steel strip may be pickled in as many as 6
separate baths and rinses. A general process and water flow
schematic is shown in Figure 22.
Table H6 summarizes the raw waste loads for the plants
studied.
Pipe and Tube Combination Acid Pickling
The formed pipe or tube is immersed in the pickle baths and
rinsed. Rinsing may be by immersion, although the pipe may
also be spray-rinsed. Table 46 summarizes the raw waste
loads for the plants studied.
Other Batch Combination Acid Pickling
A generalized process and water flow schematic is shown in
Figure 22, and the raw waste loads for the plants studied
are shown in Table 16.
SALT BATH SCALE REMOVAL
The waste effluent here is generated when the steel, after
immersion in the molten salt bath, is rinsed. Depending
upon the type of salt bath used, hexavalent chromium from
205
-------
TABLE 46
Characteristics of
Combination Acid Pickling -
Plant Raw Waste Loads
Continuous
- Plant Wastes
Characteristics
Flow, gal/ton
Suspended Solids, mg/1
Oil and Grese, mg/1
Iron, mg/1
Chromium, mg/1
Nickel, mg/1
Fluoride, mg/1
pH Units,
Plants
-A
1,378
338
1.7
68.4
26.8
17.6
164.8
3.1
D
1,016
67
16.3
400.4
48.4
31.4
47.5
3.0
I
1,814
562
0.7
61.5
17.1
6
33.3
6.5
0
974
;80
9.9
1.8
0.5
2.1
16
8.0
Batch Pipe and Tube
Characteristics
Flow, gal/ton
Suspended Solids, mg/1
Oil and Grease, mg/1
Iron, mg/1
Chromium, Total, mg/1
Cyanide, mg/1
Nickel, mg/1
Copper, mg/1
Lead, mg/1
Fluoride, mg/1
pH Units
Plants
U
677
4
3
1,080
152
70
1.4
0
12
10.4
206
-------
TABLE 46 (Cont'd)
OTHER BATCH
Characteristics Plants
Flow, gal/ton 91 279 140
Suspended Solids, mg/1 106 8 173
Oil and Grease, mg/1 5 0.7 1.7
Iron, mg/1 216 60.2 135
Chromium, mg/1 137 12.8 24.4
Nickel, mg/1 241 9.1 12.5
Fluoride, mg/1 1,725 261.6 0.5
pH Units 2.4 2.3 2.9
207
-------
kolene operations or cyanide (from hydride operations) may
be contained in the rinse.
Reliable information on wastewater volumes per ton of steel
processed were available from 4 plant survey sampling
points, all of which were from batch operations. The
average flow of Kolene rinsewaters was 333 gals/ton in 3
operations, 2 of which handled wire and the other plate.
The flow from a hydride operation handling wire was 1205
gals/ton. The salt bath rinses thus evidently use more
water than do acid pickling rinses.
Kolene Scale Removal Rinsewaters.
A general process and water flow schematic of a kolene
molten salt bath scale removal operation is presented in
Figure 23.
Hydride Scale Removal Rinsewaters.
A general process and water flow schematic of a hydride
molten salt bath scale removal operation is presented in
Figure 24.
Wire Pickling and Coating.
Waste water results from the pickling of specialty steel
wire, and the coating thereafter. A generalized process and
water flow schematic of a copper coating operation is
presented in Figure 25. Although copper coating is shown in
the diagram, molybdenum or other metals may be plated.
The effluent volume taken as typical for purposes of
characterization is that of the measured 10-minute rinsing
of a 500-pound coil (Plant K) at a rate of 20 gpm, i.e., 800
gals/ton. The raw waste characteristics are shown in Table
49.
Continuous Alkaline Cleaning.
Waste water results from the degreasing of steel, usually
strip, in an alkaline cleaning bath. This operation may be
performed prior to annealing to prevent an undesirable
surface appearance, or prior to coating to ensure adhesion.
The rate of cleaning may be increased by electrolytic
action. A general process and water flow schematic of a
typical alkaline cleaning operation is presented in Figure
26. Raw waste characteristics are shown in Table 50.
208
-------
TABLE 47
Characteristics of
Scale Removal - Kolene - Plant Wastes
Plant Raw Waste Loads
Characteristics Plants
Flow, gal/ton 398 494 108
Suspended Solids, mg/1 427 101 231
Oil & Grease, mg/1 0.33 0.6 0.2
Iron, mg/1 0.03 0 0
Chromium, mg/1 115.5 0 439.6
Nickel, mg/1 0.01 0.04 0.03
Hexavalent Chromium, mg/1 100.0 0 424
Fluoride, mg/1 0.38 0.8 14.1
pH, units 12.2 12.0 13.1
TABLE 48
Characteristics of
Scale Removal - Hydride - Plant Wastes
Plant Raw Waste Loads
Characteristics Plant
Flow, gal/ton 1205
Suspended Solids, mg/1 370
Oil & Grease, mg/1 0.3
Iron, mg/1 0.33
Cyanide, mg/1 0.106
Fluoride, mg/1 6.4
pH, units 11.9
209
-------
TABLE 49
Characteristics
Characteristics of Wire Pickling
and Coating Plant Wastes
Plant Raw Waste Loads
Plants
Flow, gal/ton
Suspended Solids, mg/1
Oil & Grease, mg/1
Iron, mg/1
Chromium, mg/1
Cyanide, mg/1
Nickel, mg/1
Copper, mg/1
Fluoride, mg/1
pH, units
K
222
481
0
193.8
24
2.4
21
2.4
36.1
3.4
3178
57
0.6
54.8
5.2
7.2
31.1
4.1
12.1
4.6
0
1828
635
21.2
0.3
7.4
17
0.06
15.9
19.6
10.7
Characteristics
Flow, gal/ton
Suspended Solids, mg/1
Oil & Grease, mg/1
Iron, mg/1
Chromium, mg/1
Nickel, mg/1
Fluoride, mg/1
pH, units
TABLE 50
Characteristics of
Continuous Alkaline Cleaning Plant Wastes
Plant Raw Waste Loads
Plants
I
50
533
0.6
59.3
17.1
6.0
31.4
210
-------
SECTION VI
SELECTION OF POLLUTANT PARAMETERS
INTRODUCTION
The selection of the control parameters was accomplished by
a three step process. First, a broad list of pollutant
parameters to be evaluated was established. Second, the
list of anticipated control parameters and procedures for
analyses of these critical parameters was established.
Thirdly, the data from the field sampling program was
examined in detail to establish the need to deviate from the
anticipated list, based on the field experience.
BROAD LIST OF POLLUTANTS
Prior to the initiation of the plant visiting and sampling
phase of the study it was necessary to establish the list of
pollutant parameters that was to be analyzed for each type
of waste source. These parameters were selected primarily
on the basis of a knowledge of the materials used or gener-
ated in the operations, and on the basis of pollutants known
to be present as indicated by previously reported analyses.
The purpose of the broad list was to identify those
pollutants present in a significant amount but not normally
reported or known to be present to such an extent. The
parameters that may be present in steel industry wastewater
streams are presented in table form by operations as
follows:
Basic Oxygen Furnace
Vacuum Degassing
Continuous Casting and Pressure Slab Molding
Hot Forming Operations
Pipe and Tube Operations
Pickling Operations
Cold Rolling Operations
Hot Coating - Galvanizing Operations
Hot Coating - Terne Plating Operations
Table
Table
Table
Table
Table
Table
Table
Table
Table
Table
Table
Table
Table
Table
Table
Table
Table
51 -
52 -
53 -
54 -
55 -
56 -
57 -
58 -
59 -
60-1
60-2
60-3
60-4
61 -
62 -
63 -
64 -
Storage Piles
Storage Piles
Storage Piles
Coal
Stone
Ore
- Miscellaneous Runoffs
- Miscellaneous Runoffs
- Miscellaneous Runoffs
- Miscellaneous Runoffs - Slagging Operations -
Blast Furnace Slag
Combination Acid Pickling Operations
Scale Removal Operations
Wire Pickling and Coating Operations
Continuous Alkaline Cleaning Operations
211
-------
TABLE 51
BASIC OXYGEN FURNACE OPERATION
PARAMETERS
Acidity Manganese
Alkalinity Molybdenum
Aluminum Nickel
Cadmium '''Nitrate
Calcium Nitrite
Chloride *pH
Chromium Phenol
Cobalt Phosphate
Color Selenium
Copper Sulfate
Cyanide ^Suspended Solids
Dissolved Solids Titanium
'''Flow Total Solids
-'Fluoride Tungsten
Hardness Vanadium
Heat Zinc
Lead Zirconium
Magnesium
TABLE 52
VACUUM DEGASSING OPERATION
PARAMETERS
Acidity ^Manganese
Alkalinity Molybdenum
Aluminum Nickel
Cadmium -'Nitrate
Calcium Nitrite
Chloride Oil £ Grease
Chromium *pH
Cobalt Phenol
Color Phosphate
Copper Selenium
Cyanide Silicon
Dissolved Solids Sulfate
'''Flow -'Suspended Solids
Fluoride Titanium
Hardness Total Solids
Heat Tungsten
Iron Vanadium
-Lead '''Zinc
Magnesium Zirconium
'''Effluent limitations were established based on these
parameters.
212
-------
TABLE 53
CONTINUOUS CASTING g PRESSURE SLAB MOLDING OPERATION
PARAMETERS
Acidity
Alkalinity
Aluminum
Cadmium
Calcium
Chloride
Chromium
Cobalt
Color
Copper
Cyanide
Dissolved Solids
*Flow
Fluoride
Hardness
Heat
Iron
Lead
Magnesium
Manganese
Mercury
Molybdenum
Nickel
Nitrate
Nitrite
*0il £ Grease
*pH
Phenol
Phosphate
Selenium
Silicon
Sulfate
'^Suspended Solids
Titanium
Total Solids
Tungsten
Vanadium
Zinc
Zirconium
213
-------
TABLE 54
HOT FORMING OPERATION
PARAMETERS
Acidity (Free and Total)
Alkalinity (Pht. and M.O.)
BODfi
Chloride
.COD
Dissolved Solids
*Flow
Hardness, Total
Heat
Iron, Total
Mercury
Nitrate
*0il and Grease
*pH
Phosphorus, Total
Sulfate
*Suspended Solids
Total Solids
TABLE 55
PIPE AND TUBE OPERATION
PARAMETERS
Acidity (Free and Total)
Alkalinity (Pht. and M.O.)
BOD_5
Chloride
COD
Color
Dissolved Solids
*Flow
Heat
Iron, Total
Mercury
*0il and Grease
*pH
Sulfate
*Suspended Solids
Total Solids
214
-------
TABLE 56
PICKLING OPERATION
PARAMETERS
Acidity (Free and Total)
Alkalinity (Pht. andM.O.)
Chloride
COD
Color
Dissolved Solids
*Flow
Heat
*Iron, Dissolved
Iron, Ferrous
Iron, Total
Lead
Mercury
*0il and Grease
*pH
Phosphorous, Ortho
Phosphorous, Total
Silica
Sulfate
Sulfide
*Suspended Solids
TOC
Total Solids
Turbidity
TABLE 57
COLD ROLLING OPERATION
PARAMETERS
Acidity (Free and Total)
Alkalinity (Pht. and M.O.)
BOD5_
Chloride
COD
Color
Dissolved Solids
*Flow
Heat
*Iron, Total
Mercury
*0il and Grease
*pH
Phosphate, Total
Phosphate, Ortho
Sulfate
Surfactant (ABS)
*Suspended Solids
Total Solids
Turbidity
215
-------
TABLE 58
HOT COATING - GALVANIZING OPERATION
PARAMETERS
Acidity (Free and Total)
Alkalinity (Pht. andM.O.)
Ammonia
BOD_5
COD
Chloride
*Chromium, Hexavalent
*Chromium, Total
Color
Copper
Cyanide, Free and Total
Dissolved Matter
*Flow
Fluoride
Heat
Iron, Dissolved
Iron, Total
Lead
Mercury
Nickel
Nitrate
Nitrogen
*pH
Phosphate, Ortho and Total
Solvent Extract Matter
Sulfate
Sulfide
*Suspended Matter
Tin
TOC
Total Matter
Turbidity (J.T.U.)
*Zinc
216
-------
TABLE 59
HOT COATING - TERNE PLATING OPERATION
PARAMETERS
Acidity (Free and Total)
Alkalinity (Pht. andM.O.)
Ammonia
BOD
COD
Chloride
Chromium, Hexavalent
Chromium, Total
Color
Copper
Dissolved Matter
*Flow
Heat
Iron, Dissolved
Iron, Total
*Lead
Mercury
Nickel
Nitrate
Nitrogen
*pH
Phosphate, Ortho
Phosphate, Total
Solvent Extract Matter
Sulfate
Sulfide
*Suspended Matter
TOG
Total Matter
*Tin
Turbidity (J.T.U.)
Zinc
217
-------
TABLE 60-1
MISCELLANEOUS RUNOFFS - STORAGE PILES - COAL
PARAMETERS
Acidity (Free and Total)
Alkalinity (Pht. andM.O.)
*Ammonia
Beryllium
*BOD
COD
Chloride
Color
*Cyanide, Free and Total
Dissolved Matter
*Flow
Heat
Mercury
Nitrogen
Odor
*pH
*Phenol
*Solvent Extractable Matter (Hexane)
Sulfate
Sulfide
*Suspended Matter
Thiocyanate
TOC
Turbidity
218
-------
TABLE 60-2
MISCELLANEOUS RUNOFFS - STORAGE PILES - STONE
PARAMETERS
Acidity (Free and Total)
Alkalinity (Pht. and M.O.)
Aluminum
Bicarbonate
Calcium
Carbonate
Chloride
Color
Dissolved Matter
Flow
Fluoride
Hardness, Total
Hardness, Calcium
Heat
Iron, Total
Magnesium
Mercury
Odor
PH
Potassium
Silica, Total
Sodium
Solvent Extractable Matter (Hexane)
Sulfate
Suspended Matter
TOG
Turbidity
219
-------
TABLE 60-3
MISCELLANEOUS RUNOFFS - STORAGE PILES - ORE
PARAMETERS
Acidity (Free and Total)
Alkalinity (Pht. andM.O.)
Aluminum
Chloride
Color
Copper
Dissolved Matter
Flow
Fluoride
Hardness, Total
Heat
Iron, Total
Iron, Dissolved
Manganese
Mercury
Odor
PH
Silica, Total
Solvent Extractable Matter (Hexane)
Sulfate
Sulfide
Suspended Matter
TOC
Turbidity
Zinc
220
-------
TABLE 60-U
MISCELLANEOUS RUNOFFS - SLAGGING OPERATIONS
BLAST FURNACE SLAG
PARAMETERS
Acidity (Free and Total)
*Alkalinity (Pht. andM.O.)
Aluminum
Chloride
Color
Copper
Dissolved Matter
*Flow
Fluoride
*Hardness/ Total
Heat
Iron
Lead
Manganese
Mercury
Nitrate
Odor
*pH
Phosphate, Total
Silica, Total
Solvent Extractable Matter (Hexane)
Sulfate
*Sulfide
*Sulfite
Suspended Matter
Zinc
221
-------
TABLE 61
COMBINATION ACID PICKLING OPERATION
PARAMETERS
Acidity
Alkalinity
Aluminum
Cadmium
Calcium
Chloride
*Chromium (Total £ Hex.)
Cobalt
Color
Copper
Cyanide
Dissolved Solids
*Flow
^Fluoride
Hardness
Heat
*Iron
Lead
Magnesium
Manganese
Mercury
Molybdenum
*Nickel
Nitrate
Nitrite
Oil £ Grease
*pH
Phenol
Phosphate
Selenium
Silicon
Sulfate
"''Suspended Solids
Titanium
Total Solids
Tungsten
Vanadium
Zinc
Zirconium
TABLE 62
SCALE REMOVAL OPERATION
PARAMETERS
Acidity
Alkalinity
Aluminum
Cadmium
Calcium
Chloride
'''Chromium (Total & Hex.)
Cobalt
Color
Copper
"Cyanide
Dissolved Solids
*Flow
Fluoride
Hardness
Heat
*Iron
Lead
Magnesium
Manganese
Mercury
Molybdenum
Nickel
Nitrate
Nitrite
Oil £ Grease
*pH
Phenol
Phosphate
Selenium
Silicon
Sulfate
"Suspended Solids
Titanium
Total Solids
Tungsten
Vanadium
Zinc
Zirconium
222
-------
TABLE 63
WIRE PICKLING S COATING OPERATION
PARAMETERS
Acidity Manganese
Alkalinity Molybdenum
Aluminum -'Nickel
Cadmium Nitrate
Calcium Nitrite
Chloride Oil S Grease
*Chromium *pH
Cobalt Phenol
Color Phosphate
'''Copper Selenium
'"'Cyanide Silicon
Dissolved Solids Sulfate
*Flow -'Suspended Solids
-'Fluoride Titanium
Hardness Total Solids
Heat Tungsten
-'Iron Vanadium
Lead Zinc
Magnesium Zirconium
TABLE 64
•
CONTINUOUS ALKALINE CLEANING OPERATION
PARAMETERS
Acidity Heat
Alkalinity '''Iron
Calcium Lead
*Chromium Magnesium
Copper *Nickel
Cyanide Oil £ Grease
Dissolved Solids *pH
"Flow '''Suspended Solids
Fluoride Total Solids
Hardness Zinc
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RATIONALE FOR SELECTION OF CONTROL PARAMETERS
On the basis of prior analyses and experience, the major
wastewater parameters that are generally considered of
pollutional significance for the iron and steel industry
include suspended solids, oil and grease, iron, total and
hexavalent chromium, tin, lead, nickel, fluoride, nitrate,
manganese, copper, cyanide and zinc. Other parameters are
present in significant amounts but were not established as
control parameters because their presence in the effluent is
not as significant, and the cost of treatment and technology
for removal in these operations is considered to be beyond
the scope of best practicable or best available technology
at this time. In addition, some parameters cannot be desig-
nated as control parameters until sufficient data is made
available on which to base effluent limitations or until
sufficient data on treatment capabilities is developed.
The concentration of iron appearing in the effluent is a
function of the chemical form in which it is present and on
the pH and temperature of the effluent. In the raw steel
making operations the iron is present in the very insoluable
oxide form and on this basis soluble iron did not need to be
established as a control parameter for these operations.
The suspended solids limitations places a limit on the iron
present in suspended or insoluble form. Standard raw waste
loads and guidelines are developed only on the critical
parameters which were starred in the tables. Multiple
analyses of these anticipated control parameters were
performed to give added accuracy to the data.
Suspended solids, oil, and pH were selected for most
industry subcategories because they are indicators of the
degree to which effluent streams are segregated, are primary
measurements of the degree of treatment afforded, indicate
accidental spills and maintenance of good housekeeping
practices, and will usually indicate practices which may not
be part of a planned effluent treatment scheme. Excessive
effluent suspended solids concentrations, for example, may
indicate that a clarifer has been bypassed, that proper
chemical treatment has not been provided, that a scale pit
has been dredged improperly, or that a sand filter has been
backwashed into a sewer. Oil in a noncontact cooling water
effluent may indicate inadvertant mixture with process water
and excessive effluent oil concentrations can indicate oil
spills or failure of oil removal equipment. Lower than
expected effluent pH levels can indicate improper
neutralization of pickle liquor, and spills, unintended
contamination of noncontact cooling water, or excessive use
of acids in cooling system cleaning.
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RATIONALE FOR SELECTION OF CRITICAL PARAMETERS BY OPERATION
The rationale for selection of the major waste parameters is
given below.
Steelmaking Operations
The waterborne wastes from the steelmaking operations result
from scrubbing of the gas stream with water to prevent air
pollution and for noncontact cooling. Hence, basic oxygen
furnace waste waters may contain suspended solids and
fluorides. Fluorspar, one of the basic raw materials in
steelmaking, is the source of fluorides.
Vacuum Degassing Subcategory
In the vacuum degassing process, steel is further refined by
subjecting the steel in the ladle to a high vacuum in an en-
closed refractory lined chamber. Steam jet ejectors with
barometric condensers are used to draw the vacuum. In the
refining process certain alloys are added which may be drawn
into the gas stream. In addition, the system is purged with
nitrogen so as to have no residual CO. Therefore, the
wastewater products from this operation are condensed steam
and waste water containing suspended solids, zinc,
manganese, lead, and nitrates.
Continuous Casting and Pressure Slab Molding
Wastewaters from the continuous casting operations result
from washing scale from the surface of the steel with spray
water. Therefore, continuous casting waste waters may con-
tain significant quantities of suspended matter and oil.
The mold cooling and machine cooling systems are usually
closed systems and the water picks up only heat. For
continuous casting and pressure slab molding, the cast
product or mold is cooled by direct contact spray water and
the principal contaminant is suspended solids from surface
scale and/or mold lining. Additionally, oil from machinery
lubrication finds its way into the water effluent and is
thus a contaminant to be considered.
Hot Forming and Pipe and Tube Operations
Wastewaters from hot forming and pipe and tube operations
result from washing scale from the surface of the steel with
water, and in the water used to transport the scale through
the flume beneath the mill line; the water used to cool the
rolled product becomes part of the mill effluent. The
effluents from hot mills contain suspended particles of
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scale and oils which originate in the hydraulic and
lubricating systems. The scale particles range from large
pieces to submicron sizes, depending upon the hot forming
operation, and are mixtures of the various iron oxides. The
oils in such effluents are only slightly water-miscible and
appear as flotant oil.
Cold Rolling Operations
Effluents from cold rolling operations contain emulsified
oils and suspended solids resulting from stable oil emul-
sions utilized in the cold rolling and reduction process.
Pickling Operations
Spent pickling solutions and acid rinse waters represent by
far the most significant source of these wastes. Spent
pickling solutions from continuous strip picklers contain 5%
to 9% free acid and 10X to 16X iron salts; from batch
operations, such solutions contain 0.5X to 2.055 free acid
and 15% to 22% iron salts. Approximately 10-15X of the acid
used in pickling is discharged in the rinse waters as highly
diluted free acid and iron salts. Hydrochloric and sulfuric
acids are the most widely used pickling acids for carbon
steel.
Sulfuric acid pickling produces waste waters containing free
acid and acid salts, primarily ferrous sulfate. Suspended
solids and pH indicate the effectiveness of neutralization
and precipitated solids removal, while soluble iron measures
the effectiveness of dissolved metals precipitation since
other metals are relatively low in concentration.
For Combination Acid Pickling, Scale Removal, Continuous
Alkaline Cleaning, and Wire Coating and Pickling suspended
solids and pH were selected because they are primary
indicators of the effectiveness of neutralization and solids
separation efficiency. The metals were selected on the
basis that they are present in the wastewaters in
significant concentrations and that the control of these
specific constituents will effectively control others that
are not specified. Copper is precipitated to the maximum
degree at the same pH as nickel. Iron is, of course, the
most prevalent of all the metals in most pickling and
cleaning wastewaters.
Cyanide is specified because of its potential from hydride
rinses and hexavalent chromium is specified because of its
high concentration in kolene rinses. Fluoride is specified
because of the widespread use of hydrofluoric acid. The
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latter three constituents are also specified because they
may be present in potentially harmful quantities.
For Wire Coating and Pickling, the parameters from
combination acid pickling were selected for similar reasons
to the above and, additionally, copper was selected because
it is present in wastewaters from wire coating. Cyanide is
additionally specified because it may be present in
potentially harmful quantities.
Hot Coating Operations
Wastewater effluents from these processes result from
rinsing and quenching operations. In addition to suspended
solids and oils these effluents may contain acids, alkalies,
and soluble metals.
RATIONALE FOR THE SELECTION OF POLLUTANT PARAMETERS
I. Pollutant Properties
•
Acidity and Alkalinity - pH
Although not a specific pollutant, pH is related to the
acidity or alkalinity of a waste water stream. It is not a
linear or direct measure of either, however, it may properly
be used as a surrogate to control both excess acidity and
excess alkalinity in water. The term pH is used to describe
the hydrogen ion - hydroxyl ion balance in water.
Technically, pH is the hydrogen ion concentration or
activity present in a given solution. pH numbers are the
negative logarithim of the hydrogen ion concentration. A pH
of 7 generally indicates neutrality or a balance between
free hydrogen and free hydroxyl ions. Solutions with a pH
above 7 indicate that the solution is alkaline, while a pH
below 7 indicate that the solution is acid.
Knowledge of the pH of water or waste water is useful in
determining necessary measures for corrosion control,
pollution control, and disinfection. Waters with a pH below
6.0 are corrosive to water works structures, distribution
lines, and household plumbing fixtures and such corrosion
can add constituents to drinking water such as iron,
copper, zinc, cadmium, and lead. Low pH waters not only
tend to dissolve metals from structures and fixtures but
also tend to redissolve or leach metals from sludges and
bottom sediments. The hydrogen ion concentration can affect
the "taste" of the water and at a low pH, water tastes
"sour".
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Extremes of pH or rapid pH changes can exert stress
conditions or kill aquatic life outright. Even moderate
changes from "acceptable" criteria limits of pH are
deleterious to some species. The relative toxicity to
aquatic life of many materials is increased by changes in
the water pH. For example, metalocyanide complexes can
increase a thousand-fold in toxicity with a drop of 1.5 pH
units. Similarly, the toxicity of ammonia is a function of
pH. The bactericidal effect of chlorine in most cases is
less as the pH increases, and it is economically
advantageous to keep the pH close to 7.
Oil and Grease
Because of widespread use, oil and grease occur often in
waste water streams,. These oily wastes may be classified as
follows:
1. Light Hydrocarbons - These include light fuels such
as gasoline, kerosene, and jet fuel, and
miscellaneous solvents used for industrial
processing, degreasing, or cleaning purposes. The
presence of these light hydrocarbons may make the
removal of other heavier oily wastes more
difficult.
2. Heavy Hydrocarbons, Fuels, and Tars - These include
the crude oils, diesel oils, #6 fuel oil, residual
oils, slop oils, and in some cases, asphalt and
road tar.
3. Lubricants and Cutting Fluids - These generally
fall into two classes: non-emulsifiable oils such
as lubricating oils and greases and emulsifiable
oils such as water soluble oils, rolling oils,
cutting oils, and drawing compounds. Emulsifiable
oils may contain fat soap or various other
additives.
4. Vegetable and animal fats and oils - These
originate primarily from processing of foods and
natural products.
These compounds can settle or float and may exist as
solids or liquids depending upon factors such as method
of use, production process, and temperature of waste
water.
Oils and grease even in small quantities cause troublesome
taste and odor problems. Scum lines from these agents are
produced on water treatment basin walls and other
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containers. Fish and water fowl are adversely affected by
oils in their habitat. Oil emulsions may adhere to the
gills of fish causing suffocation, and the flesh of fish is
tainted when they eat microorganisms that were exposed to
waste oil. Deposition of oil in the bottom sediments of
water can serve to inhibit normal benthic growth. Oil and
grease exhibit an oxygen demand.
Levels of oil and grease which are toxic to aquatic
organisms vary greatly, depending on the type and the
species susceptibility. However, it has been reported that
crude oil in concentrations as low as 0.3 mg/1 is extremely
toxic to fresh-water fish. It has been recommended that
public water supply sources be essentially free from oil and
grease.
Oil and grease in quantities of 100 1/sq km show up as a
sheen on the surface of a body of water. The presence of
oil slicks prevent the full aesthetic enjoyment of water.
The presence of oil in water can also increase the toxicity
of other substances being discharged into the receiving
bodies of water. Municipalities frequently limit the
quantity of oil and grease that can be discharged to their
waste water treatment systems by industry.
Total Suspended Solids (TSS)
Suspended solids include both organic and inorganic
materials. The inorganic compounds include sand, silt, and
clay. The organic fraction includes such materials as
grease, oil, tar, and animal and vegetable waste products.
These solids may settle out rapidly and bottom deposits are
often a mixture of both organic and inorganic solids.
Solids may be suspended in water for a time, and then settle
to the bed of the stream or lake. These solids discharged
with man's wastes may be inert, slowly biodegradable
materials, or rapidly decomposable substances'. While in
suspension, they increase the turbidity of the water, reduce
light penetration and impair the photosynthetic activity of
aquatic plants.
Suspended solids in water interfere with many industrial
processes, cause foaming in boilers and incrustations on
equipment exposed to such water, especially as the
temperature rises. They are undesirable in process water
used in the manufacture of steel., in the textile industry,
in laundries, in dyeing and in cooling systems.
Solids in suspension are aesthetically displeasing. When
they settle to form sludge deposits on the stream or lake
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bed, they are often damaging to the life in water. Solids,
when transformed to sludge deposits, may do a variety of
damaging things, including blanketing the stream or lake bed
and thereby destroying the living spaces for those benthic
organisms that would otherwise occupy the habitat. When of
an organic nature, solids use a portion or all of the
dissolved oxygen available in the area. Organic materials
also serve as a food source for sludgeworms and associated
organisms.
Disregarding any toxic effect attributable to substances
leached out by water, suspended solids may kill fish and
shellfish by causing abrasive injuries and by clogging the
gills and respiratory passages of various aguatic fauna.
Indirectly, suspended solids are inimical to aquatic life
because they screen out light, and they promote and maintain
the development of noxious conditions through oxygen
depletion. This results in the killing of fish and fish
food organisms. Suspended solids also reduce the
recreational value of the water.
II. Pollutant Materials
Ammonia (NH3) and Nitrate
Ammonia occurs in surface and ground waters as a result of
the decomposition of nitrogenous organic matter. It is one
of the constituents of the complex nitrogen cycle. It may
also result from the discharge of industrial wastes from
chemical or gas plants, from refrigeration plants, from
scouring and cleaning operations where "ammonia water" is
used from the processing of meat and poultry products, from
rendering operations, from leather tanning plants, and from
the manufacture of certain organic and inorganic chemicals.
Because ammonia may be indicative of pollution and because
it increases the chlorine demand, it is recommended that
ammonia nitrogen in public water supply sources not exceed
0.5 mg/1.
Ammonia exists in its non-ionized form only at higher pH
levels and is most toxic in this state. The lower the pH,
the more ionized ammonia is formed, and its toxicity
decreases. Ammonia, in the presence of dissolved oxygen, is
converted to nitrate (NO_3) by nitrifying bacteria. Nitrite
(NQ2J , which is an intermediate product between ammonia and
nitrate, sometimes occurs in quantity when depressed oxygen
conditions permit. Ammonia can exist in several other
chemical combinations including ammonium chloride and other
salts.
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Nitrates are considered to be among the objectionable
components of mineralized waters. Excess nitrates cause
irritation to the gastrointestinal tract, causing diarrhea
and diuresis. Methemoglobinemia, a condition characterized
by cyanosis and which can result in infant and animal
deaths, can be caused by high nitrate concentrations in
waters used for feeding. Ammonia can exist in several other
chemical combinations, including ammonium chloride and other
salts. Evidence exists that ammonia exerts a toxic effect
on all aquatic life depending upon the pH, dissolved oxygen
level, and the total ammonia concentration in the water. A
significant oxygen demand can result from the microbial
oxidation of ammonia. Approximately 4.5 grams of oxygen are
required for every gram of ammonia that is oxidized.
Ammonia can add to eutrophication problems by supplying
nitrogen to aquatic life. Ammonia can be toxic, exerts an
oxygen demand, and contributes to eutrophication.
Chromium (Cr)
Chromium is an elemental metal usually found as a chromite
(FeCrftW). The metal is normally processed by reducing the
oxide with aluminum.
Chromium and its compounds are used extensively throughout
industry. It is used to harden steel and as an ingredient
in other useful alloys. Chromium is also used in the
electroplating industry as an ornamental and corrosion
resistant plating on steel and can be used in pigments and
as a pickling acid (chromic acid).
The two most prevalent chromium forms found in industry
waste waters are hexavalent and trivalent chromium. Chromic
acid used in industry is a hexavalent chromium compound
which is partially reduced to the trivalent form during use.
Chromium can exist as either trivalent or hexavalent
compounds in raw waste streams. Hexavalent chromium treat-
ment involves reduction to the trivalent form prior to
removal of chromium from the waste stream as a hydroxide
precipitate.
Chromium, in its various valence states, is hazardous to
man. It can produce lung tumors when inhaled and induces
skin sensitizations. Large doses of chromates have
corrosive effects on the intestinal tract and can cause
inflammation of the kidneys. Levels of chromate ions that
have no effect on man appear to be so low as to prohibit
determination to date. The recommendation for public water
supplies is that such supplies contain no more than 0.05
mg/1 total chromium.
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The toxicity of chromium salts to fish and other aquatic
life varies widely with the species, temperature, pHr
valence of the chromium and synergistic or antagonistic
effects, especially that of hard water. Studies have shown
that trivalent chromium is more toxic to fish of some types
than hexavalent chromium. Other studies have shown opposite
effects. Fish food organisms and other lower forms of
aquatic life are extremely sensitive to chromium and it also
inhibits the growth of algae. Therefore, both hexavalent
and trivalent chromium must te considered harmful to
particular fish or organisms.
Copper (Cu)
Copper is an elemental metal that is sometimes found free in
nature and is found in many minerals such as cuprite,
malachite, azurite, chalcopyrite, and bornite. Copper is
obtained from these ores by smelting, leaching, and
electrolysis. Significant industrial uses are in the
plating, electrical, plumbing, and heating equipment
industries. Copper is also commonly used with other
minerals as an insecticide and fungicide.
Traces of copper are found in all forms of plant and animal
life, and it is an essential trace element for nutrition.
Copper is not considered to be a cumulative systemic poison
for humans as it is readily excreted by the body, but it can
cause symptoms of gastroenteritis, with nausea and
intestinal irritations, at relatively low dosages. The
limiting factor in domestic water supplies is taste.
Threshold concentrations for taste have been generally
reported in the range of 1.0-2.0 mg/1 of copper while
concentrations of 5 to 7.5 mg/1 have made water completely
undrinkable. It has been recommended that the copper in
public water supply sources not exceed 1 mg/1.
Copper salts cause undesirable color reactions in the food
industry and cause pitting when deposited on some other
metals such as aluminum and galvanized steel. The textile
industry is affected when copper salts are present in water
used for processing of fabrics. Irrigation waters con-
taining more than minute quantities of copper can be
detrimental to certain crops. The toxicity of copper to
aquatic organisms varies significantly, not only with the
species, but also with the physical and chemical
characteristics of the water, including temperature,
hardness, turbidity, and carbon dioxide content. In hard
water, the toxicity of copper salts may be reduced by the
precipitation of copper carbonate or other insoluble
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compounds. The sulfates of copper and zinc, and of copper
and cadmium are synergistic in their toxic effect on fish.
Copper concentrations less than 1 mg/1 have been reported to
be toxic, particularly in soft water, to many kinds of fish,
crustaceans, mollusks, insects, phytoplankton and
zooplankton. Concentrations of copper, for example, are
detrimental to some oysters above .1 ppm. Oysters cultured
in sea water containing 0.13-0.5 ppm of copper deposited the
metal in their bodies and became unfit as a food substance.
Cyanide (CN)
Cyanide is a compound that is widely used in industry
primarily as sodium cyanide (NaCN) or hydrocyanic acid
(HCN). The major use of cyanides is in the electroplating
industry where cyanide baths are used to hold ions such as
zinc and cadmium in solution. Cyanides in various compounds
are also used in steel plants, chemical plants, photographic
processing, textile dying, and ore processing.
Of all the cyanides, hydrogen cyanide (HCN) is probably the
most acutely lethal compound. HCN dissociates in water to
hydrogen ions and cyanide ions in a pH dependent reaction.
The cyanide ion is less acutely lethal than HCN. The
relationship of pH to HCN shows that as the pH is lowered to
below 7 there is less than IX of the cyanide molecules in
the form of the CN ion and the rest is present as HCN. When
the pH is increased to 8, 9, and 10, the percentage of cya-
nide present as CN ion is 6.7, 42, and 87%, respectively.
The toxicity of cyanides is also increased by increases in
temperature and reductions in oxygen tensions. A
temperature rise of 10°C produced a two- to threefold
increase in the rate of the lethal action of cyanide.
In the body, the CN ion, except for a small portion exhaled,
is rapidly changed into a relatively non-toxic complex
(thiocyanate) in the liver and eliminated in the urine.
There is no evidence that the CN ion is stored in the body.
The safe ingested limit of cyanide has been estimated at
some-thing less than 18 mg/day, part of which comes from
normal environment and industrial exposure. The average
fatal dose of HCN by ingestion by man is 50 to 60 mg. It
has been recommended that a limit of 0.2 mg/1 cyanide not be
exceeded in public water supply sources.
The harmful effects of the cyanides on aquatic life is
affected by the pH, temperature, dissolved oxygen content,
and the concentration of minerals in the water. The
biochemical degradation of cyanide is not affected by
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temperature in the range of 10 degrees C to 35 degrees C
while the toxicity of HCN is increased at higher
temperatures.
On lower forms of life and organisms, cyanide does not seem
to be as toxic as it is toward fish. The organisms that
digest BOD were found to be inhibited at 1.0 mg/1 and at 60
mg/1 although the effect is more one of delay in exertion of
BOD than total reduction.
Certain metals such as nickel may complex with cyanide to
reduce lethality, especially at higher pH values. On the
other hand, zinc and cadmium cyanide complexes may be
exceedingly toxic.
Fluoride
Fluorine is the most reactive of the nonmetals and is never
found free in nature. It is a constituent of fluorite or
fluorspar, calcium fluoride, cryolite, and sodium aluminum
fluoride. Due to their origins, fluorides in high
concentrations are not a common constituent of natural
surface waters; however, they may occur in hazardous
concentrations in ground waters.
Fluoride can be found in plating rinses and in glass etching
rinse waters. Fluorides are also used as a flux in the
manufacture of steel, for preserving wood and mucilages, as
a disinfectant and in insecticides.
Fluorides in sufficient quantities are toxic to humans with
doses of 250 to 450 mg giving severe symptoms and 4.0 grams
causing death. A concentration of 0.5 g/kg of body weight
has been reported as a fatal dosage.
There are numerous articles describing the effects of
fluoride-bearing waters on dental enamel of children; these
studies lead to the generalization that water containing
less than 0.9 to 1.0 mg/1 of fluoride will seldom cause
mottled enamel in children, and for adults, concentrations
less than 3 or 4 mg/1 are not likely to cause endemic
cumulative fluorosis and skeletal effects. Abundant
literature is also available describing the advantages of
maintaining 0.8 to 1.5 mg/1 of fluoride ion in drinking
water to aid in the reduction of dental decay, especially
among children. The recommended maximum levels of floride
in public water supply sources range from 1.4 to 2.4 mg/1.
Fluorides may be harmful in certain industries, particularly
those involved in the production of food, beverages.
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pharmaceutical, and medicines. Fluorides found in
irrigation waters in high concentrations (up to 360 mg/1)
have caused damage to certain plants exposed to these
waters. Chronic fluoride poisoning of livestock has been
observed in areas where water contained 10 to 15 mg/1
fluoride. Concentrations of 30 - 50 mg/1 of fluoride in the
total ration of dairy cows is considered the upper safe
limit. Fluoride from waters apparently does not accumulate
in soft tissue to a significant degree and it is transferred
to a very small extent into the milk and to a somewhat
greater degree into eggs. Data for fresh water indicate
that fluorides are toxic to fish at concentrations higher
than 1.5 mg/1.
Iron (Fe)
Iron is an abundant metal found in the earth's crust. The
most common iron ore is hematite from which iron is obtained
by reduction with carbon. Other forms of commercial ores
are magnetite and taconite. Pure iron is not often found in
commercial use, but it is usually alloyed with other metals
and minerals, the most common being carbon.
Iron is the basic element in the production of steel and
steel alloys. Iron with carbon is used for casting of major
parts of machines and it can be machined, cast, formed, and
welded. Ferrous iron is used in paints, while powdered iron
can be sintered and used in powder metallurgy. Iron
compounds are also used to precipitate other metals and
undesirable minerals from industrial waste water streams.
Iron is chemically reactive and corrodes rapidly in the
presence of moist air and at elevated temperatures. In
water and in the presence of oxygen, the resulting products
of iron corrosion may be pollutants in water. Natural
pollution occurs from the leaching of soluble iron salts
from soil and rocks and is increased by industrial waste
water from pickling baths and other solutions containing
iron salts.
Corrosion products of iron in water cause staining of
porcelain fixtures, and ferric iron combines with the tannin
to produce a dark violet color. The presence of excessive
iron in water discourages cows from drinking and, thus,
reduces milk production. High concentrations of ferric and
ferrous ions in water kill most fish introduced to the
solution within a few hours. The killing action is
attributed to coatings of iron hydroxide precipitates on the
gills. Iron oxidizing bacteria are dependent on iron in
water for growth. These bacteria form slimes that can
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affect the esthetic values of bodies of water and cause
stoppage of flows in pipes.
Iron is an essential nutrient and micronutrient for all
forms of growth. Drinking water standards in the U. S. have
set a recommended limit of 0.3 mg/1 of iron in domestic
water supplies based not on the physiological
considerations, but rather on aesthetic and taste
considerations of iron in water.
Lead (Pb)
Lead is used in various solid forms both as a pure metal and
in several compounds. Lead appears in some natural waters,
especially in those areas where mountain limestone and
galena are found. Lead can also be introduced into water
from lead pipes by the action of the water on the lead.
Lead is a toxic material that is foreign to humans and
animals. The most common form of lead poisoning is called
plumbism. Lead can be introduced into the body from the
atmosphere containing lead or from food and water. Lead
cannot be easily excreted and is cumulative in the body over
long periods of time, eventually causing lead poisoning with
the ingesticn of an excess of 0.6 mg per day over a period
of years. It has been recommended that 0.05 mg/1 lead not
be exceeded in public water supply sources.
Chronic lead poisoning has occurred among animals at levels
of 0.18 mg/1 of lead in soft water and by concentrations
under 2.1 mg/1 in hard water. Farm animals are poisoned by
lead more frequently than any other poison. Sources of this
occurrence include paint and water with the lead in solution
as well as in suspension. Each year thousands of wild water
fowl are poisoned from lead shot that is discharged over
feeding areas and ingested by the water fowl. The bacterial
decomposition of organic matter is inhibited by lead at
levels of 0.1 to 0.5 mg/1.
Fish and other marine life have had adverse effects from
lead and salts in their environment. Experiments have shown
that small concentrations of heavy metals, especially of
lead, have caused a film of coagulated mucus to form first
over the gills and then over the entire body probably
causing suffocation of the fish due to this obstructive
layer. Toxicity of lead is increased with a reduction of
dissolved oxygen concentration in the water.
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Manganese
Manganese metal is not found pure in nature, but its ores
are very common and widely distributed. The metal or its
salts are used^extensively in steel alloys, for dry-cell
batteries, in glass and ceramics, in the manufacture of
paints and varnishes, in inks and dyes, in matches and
fireworks, and in agriculture to enrich manganese-deficient
soils. Like iron, it occurs in the divalent and trivalent
form. The chlorides, nitrates, and sulfates are highly
soluble in water; but the oxides, carbonates, and hydroxides
are only sparingly soluble. For this reason, manganic or
manganous ions are seldom present in natural surface waters
in concentrations above 1.0 mg/1. In groundwater subject to
reducing conditions, manganese can be leached from the soil
and occur in high concentrations. Manganese frequently
accompanies iron in such ground waters and in the literature
the two are often linked together.
The recommended limitation for manganese in drinking water
in the U.S. is set at 0.05 mg/1 and internationaly (WHO) at
0.1 mg/1. These limits appear to be based on esthetic and
economic considerations rather than physiological hazards.
In concentrations not causing unpleasant tastes, manganese
is regarded by most investigators to be of no toxicological
significance in drinking water. However, some cases of
manganese poisoning have been reported in the literature. A
small outbreak of an encephalitis-like disease, with early
symptoms of lethargy and edema, was traced to manganese in
the drinking water in a village outside of Tokyo; three
persons died as a result of poisoning by well water
contaminated by manganese derived from dry-cell batteries
buried nearby. Excess manganese in the drinking water is
also believed to be the cause of a rare disease endemic in
Manchukuo.
Manganese is undesirable in domestic water supplies because
it causes unpleasant tastes, deposits on food during
cooking, stains and discolors laundry and plumbing fixtures,
and fosters the growth of some micro-organisms in
reservoirs, filters, and distribution systems.
Small concentrations of manganese - 0.2 to 0.3 mg/1 may form
heavy encrustations in piping while even small amounts may
cause noticable black spots on white laundry items.
Excessive manganese is also undesirable in water for use in
many industries, including textiles; dyeing; food
processing, distilling, brewing; ice; paper; and many
others.
237
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Nickel (Ni)
Elemental nickel is seldom found in nature in the pure
state. Nickel is obtained commercially from pentlendite and
pyrrhotite. It is a relatively plentiful element and is
widely distributed throughout the earth's crust. It occurs
in marine organisms and is found in the oceans. Depending
on the dose, the organism involved, and the type of compound
involved, nickel may be beneficial or toxic. Pure nickel is
not soluble in water but many of its salts are very soluble.
The uses of nickel are many and varied. It is machined and
formed for various products as both nickel and as an alloy
with other metals. Nickel is also used extensively as a
plating metal primarily for a protective coating for steel.
The toxicity of nickel to man is believed to be very low and
systematic poisoning of human beings by nickel or nickel
salts is almost unknown. Nickel salts have caused the
inhibition of the biochemical oxidation of sewage. They
also caused a 50 percent reduction in the oxygen utilization
from synthetic sewage in concentrations of 3.6 mg/1 to 27
mg/1 of various nickel salts.
Nickel is extremely tcxic to citrus plants. It is found in
many soils in California, generally in insoluble form, but
excessive acidification of such soil may render it soluble,
causing severe injury to or the death of plants. Many
experiments with plants in solution cultures have shown that
nickel at 0.5 to 1.0 mg/1 is inhibitory to growth.
Nickel salts can kill fish at very low concentrations.
However, it has been found to be less toxic to some fish
than copper, zinc and iron. Data for the fathead minnow
show death occurring in the range of 5-43 mg/1, depending on
the alkalinity of the water.
Nickel is present in coastal and open ocean concentrations
in the range of 0.1-6.0 ug/1, although the most common
values are 2-3 ug/1. Marine animals contain up to 100
ug/1, and marine plants contain up to 3,000 ug/1. The
lethal limit of nickel to some marine fish has been reported
as low as 0.8 ppm. Concentrations of 13.1 mg/1 have been
reported to cause a 50 percent reduction of the
photosynthetic activity in the giant kelp (Macrocystis
pyrifera) in 96 hours, and a low concentration was found to
kill oyster eggs.
238
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Tin (Sn)
Tin is not present in natural water, but it may occur in
industrial wastes. Stannic and stannous chloride are used
as mordants for reviving colors, dyeing fabrics, weighting
silk, and tinning vessels. Stannic chromate is used in
decorating porcelain, and stannic oxide is used in glass
works, dye houses, and for fingernail polishes. Stannic
sulfide is used in some lacquers and varnishes. Tin
compounds are also used in fungicides, insecticides, and
anti-helminthi cs.
No reports have been uncovered to indicate that tin is
detrimental in domestic water supplies. Traces of tin occur
in the human diet from canned foods, and it has been
estimated that the average diet contains 17.14 mg of tin per
day. Man can apparently tolerate 850 to 1000 mg per day of
free tin in his diet.
On the basis of feeding experiments, it is unlikely that any
concentration of tin that could occur in most natural waters
would be detrimental to livestock. Most species of fish can
withstand fairly large concentrations of tin; however, tin
is about ten times as toxic as copper to certain marine
organisms such as barmuls and tabworms.
Zinc (Zn)
Occurring abundantly in rocks and ores, zinc is readily
refined into a stable pure metal and is used extensively as
a metal, an alloy, and a plating material. In addition,
zinc salts are also used in paint pigments, dyes, and
insecticides. Many of these salts (for example, zinc
chloride and zinc sulfate) are highly soluble in water;
hence, it is expected that zinc might occur in many
industrial wastes. On the other hand, some zinc salts (zinc
carbonate, zinc oxide, zinc sulfide) are insoluble in water
and, consequently, it is expected that some zinc will
precipitate and be removed readily in many natural waters.
In soft water, concentrations of zinc ranging from 0.1 to
1.0 mg/1 have been reported to be lethal to fish. Zinc is
thought to exert its toxic action by forming insoluble
compounds with the mucous that covers the gills, by damage
to the gill epithelium, or possibly by acting as an internal
poison. The sensitivity of fish to zinc varies with
species, age, and condition, as well as with the physical
and chemical characteristics of the water. Some
acclimatization to the presence of the zinc is possible. it
has also been observed that the effects of zinc poisoning
239
-------
may not become apparent immediately so that fish removed
from zinc-contaminated to zinc-free water may die as long as
148 hours after the removal. The presence of copper in water
may increase the toxicity* of zinc to aquatic organisms,
while the presence of calcium or hardness may decrease the
relative toxicity.
A complex relationship exists between zinc concentrations,
dissolved oxygen, pH, temperature, and calcium and magnesium
concentrations. Prediction of harmful effects has been less
than reliable and controlled studies have not been
extensively documented.
Concentrations of zinc in excess of 5 mg/1 in public water
supply sources cause an undesirable taste which persists
through conventional treatment. Zinc can have an adverse
effect on man and animals at high concentrations.
Observed values for the distribution of zinc in ocean waters
varies widely. The major concern with zinc compounds in
marine waters is not one of actute lethal effects, but
rather one of the long term sublethal effects of the
metallic compounds and complexes. From the point of view of
accute lethal effects, invertebrate marine animals seem to
be the most sensitive organisms tested.
A variety of freshwater plants tested manifested harmful
symptoms at concentrations of 10 mg/1. Zinc sulfate has
also been found to be lethal to many plants and it could
impair agricultural uses of the water.
240
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SECTION VII
CONTROL AND TREATMENT TECHNOLOGY
RANGE AND PERMUTATIONS OF TREATMENT TECHNOLOGY AND CURRENT
PRACTICE AS EXEMPLIFIED BY PLANTS VISITED DURING THE STUDY
Table 65 presents a brief summary of the treatment practices
employed at all plants visited in this study. It shows the
variability of treatment techniques employed in the
industry.
For each subcategory, the following discussion presents a
summary of the range of technology employed within the
industry as exemplified by the plants visited. Also
included are descriptions of the nature of the technology as
applied in steel mills and more detailed discussions of
technology useful to treat or control specific pollutants.
In addition, there is a summary discussion of the intake or
water supply treatment systems.
Base Level of Treatment
In developing the technology, guidelines, and incremental
costs associated with the application of the technologies
subsequently to be selected and designated as one approach
to the treatment of effluents to achieve the BPCTCA, BATEA,
and NSPS effluent qualities, it was necessary to determine
what base or minimum level of treatment was already in
existence for practically all plants within the industry in
any given sub-category. The different technology levels
were then formulated in an "add-on" fashion to these base
levels. The various treatment models (levels of treatment)
and corresponding effluent characteristics are summarized in
Tables 66 through 87. These tables are presented in Section
VIII.
In the following lists and tables, the carbon steel plants
are those with a 2 as a suffix, as E-2, G-2, etc.
BASIC OXYGEN FURNACE
The waste water produced is primarily the result of the fume
collection system employed. There is no discharge from the
dry type precipitator system and hence no waste water
treatment is involved.
The wet high energy venturi scrubber fume collection systems
generally use steam generating type hoods closely coupled
241
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^TABLE 65
WASTE WATER TREATMENT PRACTICES OF PLANTS VISITED IN STUDY
CARBON STEEL
PLANT PRACTICE
HOT FORMING PRIMARY
A-2 Primary and secondary clarification with
partial recycle of clarified wastewaters,
accompanied by deep bed filtration of the
remainder. The filter effluent is discharged
to receiving stream.
B-2 Primary and secondary clarification followed
by de
-------
TABLE 65
PLANT PRACTICE
G-2 Primary and secondary clarification including
oil skimming, followed by sand filtration,
cooling, and total recycle.
H-2 Scale pit effluent is sent to cyclonic solids
separator with clarified water discharged,
and concentrated sludges returned to scale
pit.
1-2 Scale pit effluent treated by extended settling
in a terminal lagoon.
HOT FORMING FLAT
J-2 Primary and secondary clarification, chemical
treatment, gravity filtration and discharge
to receiving stream. •
K-2 Primary and secondary clarification, filtra-
tion, cooling and recycle for mill use. Blow-
down from system is 2-3%.
L-2 Primary clarification including oil skimming,
followed by chemical treatment, vacuum filtra-
tion, and cooling with partial blowdown of
1-2%. Treated water is reused in mill and
elsewhere in plant as makeup and noncontact
cooling water.
M-2 Primary clarification including oil skimming,
followed by chemical treatment, clarification,
filtration, and discharge to receiving stream.
N-2 Primary clarification, high flow sand filtra-
tion, cooling, and total recycle to mill.
PIPE AND TUBES
E-2 Primary settling, clarification, filtration,
cooling and recycle to other hot forming
operations.
GG-2 Primary sedimentation, oil separation, and
recycle to pond for plant use.
HH-2 Total recycle system. Settle in series of
ponds, return to reservoir for process reuse
throughout plant.
243
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TABLE 65
PLANT PRACTICE
II-2 Sedimentation, oil skimming, filtration, final
settling lagoon, and discharge to receiving
stream.
JJ-2 Primary sedimentation, mixing with acid rinses,
lagooned for evaporative cooling, and recycled
for plant reuse.
KK-2 Primary and secondary sedimentation, oil
separation, polyelectrolyte addition, and
discharge to receiving stream.
PICKLING - BATCH SULFURIC - CONCENTRATED
1-2 Spent pickle liquor disposed of via contract
hauling.
0-2 Batch evaporative crystallization of spent
sulfuric acid. Acid recovered with production
of a ferrous heptahydrate.
P-2 Batch pickle liquor regeneration by vacuum
crystallization.
Q-2 Batch pickle regeneration through cooling of
spent pickle liquor and precipitation of
ferrous sulfate heptahydrate.
R-2 Combining pickle liquor in an equalization
tank, flash mixing with acetylene sludge,
lagooning, and discharge to creek.
S-2 Spent pickle liquor disposed of via contract
hauling.
PICKLING - BATCH SULFURIC - RINSE
1-2 Rinses mixed with other plant wastes in a
terminal lagoon and discharge to receiving
stream.
0-2 Rinses recycled back as makeup to pickle tank.
P-2 Rinses metered to sewer discharge.
Q-2 Rinses and mists from filter recycled back as
makeup to pickle tank.
244
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TABLE 65
PLANT PRACTICE
R-2 Combining acid rinses with other wastes in an
equalization tank, flash mixing with acetylene
sludge, lagooning, and discharge to creek.
S-2 Standing rinse reused as makeup to pickle tank.
Running rinse is treated with lime and lagooned.
Lagoon sludges are contract hauled, and over-
flows are recycled to rinse.
PICKLING - CONTINUOUS SULFURIC
T-2 Pickle liquor regeneration by evaporative
concentration.
T-2 Rinses recycled back as makeup to pickle tank.
PICKLING - BATCH HYDROCHLORIC - CONCENTRATED
U-2 Spent pickle liquor disposed of via contract
hauling.
V-2 Spent pickle liquor disposed of via contract
hauling.
PICKLING - BATCH HYDROCHLORIC - RINSE
U-2 Rinses treated in batch treatment tank by
sodium carbonate neutralization.
V-2 Caustic neutralization of rinse water prior to
sanitary sewer discharge.
PICKLING - CONTINUOUS HYDROCHLORIC - CONCENTRATED
1-2 Spent pickle liquor disposed of via contract
hauling.
W-2 Pyrolytic regeneration of hydrochloric acid.
X-2 Spent acid recovery via hydrochloric acid
regeneration.
Y-2 Pyrolytic regeneration of hydrochloric acid.
Z-2 Neutralization of spent pickle liquor clari-
fication, with disposal of the supernatant to
the sewer.
245
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TABLE 65
PLANT PRACTICE
AA-2 Deep well disposal of spent liquor.
BB-2 Deep well disposal, or regeneration at an
off-site HC1 plant.
PICKLING - CONTINUOUS HYDROCHLORIC - RINSE
1-2 Dilution and mixing with other mill wastes
in a terminal lagoon with discharge to
receiving stream.
W-2 Dilution of rinse waters and sewer discharge.
X-2 Dilution of rinse waters and sewer discharge.
Y-2 Dilution of rinse waters and sewer discharge.
Z-2 Rinses are combined with concentrated pickle
liquor and treated by neutralization, clarifi-
cation, and discharge to sanitary sewer.
AA-2 Cascade rinse system and deep well disposal.
BB-2 Rinses mixed with cold mill wastes, neutral-
ized, clarified, lagooned and discharged to
receiving stream.
SCALE REMOVAL - SHOT BLAST
CC-2 Dry removal system, no aqueous discharge.
WIRE MAKING
1-2 Dilution and reaction with other mill wastes
in a terminal lagoon and discharge to receiving
stream.
Q-2 No process wastewaters - noncontact cooling
waters from wire drawing are discharged un-
treated.
LL-2 Mixing with other process wastewaters for
chemical treatment that includes oil skimming,
chemical reduction, coagulation, sedimentation,
clarification, and aeration.
246
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TABLE 65
PLANT
PRACTICE
COLD ROLLING
X-2
BB-2
DD-2
EE-2
FF-2
Air flotation, chemical treatment, clarifica-
tion, and plant reuse.
Mixing with acid rinse waters, neutralization,
aeration, clarification, lagooning, and dis-
charge to receiving stream.
Oil skimming, chemical treatment, sedimentation,
and discharge to receiving stream.
Oil skimming, chemical treatment, lagooning,
and sewer discharge.
Primary sedimentation, mixing, chemical treat-
ment, clarification, and sewer discharge.
HOT COATINGS - GALVANIZING
1-2
MM-2
NN-2
Dilution and reaction with other mill wastes
in a terminal lagoon and discharge to receiving
stream.
Mixing of coating wastewaters, oil separation,
aeration, sedimentation, lagooning and recircu-
lation to service water with intermittent blow-
down to receiving stream.
Lime treatment, polymer addition, and clarifica-
tion.
HOT COATINGS - TERNE PLATE
00-2
PP-2
Mixing and dilution of rinse waters prior to
discharge.
Mixing and dilution of rinse waters prior to
discharge.
247
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TABLE 65
CHARACTERISTICS OF MISCELLANEOUS RUNOFFS -
COAL STORAGE PILES AND BLAST FURNACE SLAGGING WASTES
NET PLANT RAW WASTELOADS
Coal Storage Blast Furnace
Pile Slagging
Characteristics Plant C " Plant M
Flow, 1/kkg 0 0
Ammonia, mg/1 2.20
BOD5, mg/1 15
Cyanide, Total, mg/1 3.23
pH, Units 7.6 11.5
Phenol, mg/1 0.57
Solvent Extractable Matter,
Hexane, rag/1 8.0 68.4
Sulfide, mg/1 <0.02 499
Sulfite, mg/1 - 1,560
Suspended Matter, mg/1 412 2
248
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PLANT
TABLE 65
WASTE WATER TREATMENT
PRACTICES OF PLANTS VISITED
IN STUDY
SPECIALTY STEEL
PRACTICE
BASIC OXYGEN FURNACE (WET AIR POLLUTION CONTROL)
D
VACUUM DEGASSING
Gas cleaning system wastewaters
from Basic Oxygen Furnace treated
via chemical coagulation, thickening,
and discharge to a receiving stream.
Vacuum degassing wastewaters passed
through a cooling tower and recycled.
There is no continuous blowdown
except for an infrequent purge of the
entire system.
Vacuum degassing wastewaters collected
and discharged to a receiving stream
with no treatment.
CONTINUOUS CASTING & PRESSURE SLAB MOLDING
Wastewaters treated via settling and
filtration followed by recycle with
batch blowdown of the underflow to a
receiving stream.
Spray cooling water recycled through
cooling tower with make-up water from
mold cooling water which is recycled
through separate cooling tower with
blowdown to receiving stream during
casting.
Mold cooling and flushing water settled
and discharged to a receiving stream.
249
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TABLE 65
SPECIALTY STEEL
PLANT PRACTICE
HOT FORMING (PRIMARY)
E Primary and secondary clarification,
deep bed filtration, and discharge
to river.
D Primary clarification followed by
discharge to river.
H Primary clarification followed by
discharge to river.
K Primary clarification followed by
recycle with blowdown to river.
M Primary clarification followed by
recycle with blowdown to river.
M1 Primary clarification followed by
recycle with blowdown to river.
Q Primary clarification followed by
discharge to river.
R Primary and secondary clarification
followed by discharge to river.
HOT FORMING (SECTION)
C Primary clarification and cooling followed
by recycle with blowdown to river.
H Primary clarification followed by
discharge to river.
K Primary clarification followed by minor
recycle with blowdown to river.
0 Secondary clarification followed by
recycle with further treatment of
blowdown before discharge.
0' Primary clarification followed by
recycle with further treatment of
blowdown before discharge.
Q Primary clarification followed by
discharge to river.
250
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TABLE 65
SPECIALTY STEEL
PLANT PRACTICE
HOT FORMING FLAT
F This plant utilizes Scale Pit Type
sedimentation to treat waste water
generated by the Plate Mill.
E Once-through process waste water
from the Hot Strip Mill is treated
in a flocculator-clarifier followed
by deep-bed sand filtration.
D Once-through process waste water
generated by the Hot Strip Mill
mixes with other waste water flows
and discharges to a receiving stream
without treatment.
PICKLING-SULFURIC ACID - BATCH
R This plant utilizes lime neutrali-
zation and sludge lagooning to treat
both the rinse water and waste pickle
liquor solutions generated by the
batch pickling process.
COLD ROLLING
This plant utilizes oil skimming to
remove the insoluble surface oil
and chemical addition to break the
emulsion for further separation to
treat the blowdown coolant from the
cold rolling operation.
This plant utilizes oil skimming to
remove the insoluble surface oil and
a paper filter to remove particulate
matter before recirculating the
coolant to the cold rolling process.
The skimmed oil is reprocessed by an
outside firm. There is no other dis-
charge from this system.
251
-------
This plant utilizes a paper filter to
remove particulates from the coolant
before it is recirculated to the cold
rolling process. There is no dis-
charge from this system. The entire
volume is removed periodically and
reprocessed.
COMBINATION ACID PICKLING
This plant utilizes equalization,
lime neutralization, chromium reduc-
tion clarification, chemical treat-
ment, sludge thickening, and sludge
dewatering via centrifuging to
treat waste waters generated in the
continuous strip pickling process.
Acid rinses generated by the
Continuous Strip Pickling Process
are discharged without treatment.
This plant utilizes lime neutrali-
zation of the spent pickling acids,
mixing with the acid rinses, and
sedimentation in a lagoon to treat
the waste water generated by the
Strip Pickling Process.
This plant utilizes equalization,
sodium hydroxide neutralization,
aeration, chemical treatment, and
sludge lagooning to treat process
rinse water generated by the con-
tinuous strip pickling operation.
This plant utilizes batch-type lime
neutralization of the acid rinses
and lime neutralization followed
by evaporation of the spent pickling
acids generated by the pickling
process.
This plant utilizes equalization,
lime neutralization, chemical
252
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SCALE REMOVAL
coagulation, and sedimentation to
treat waste water generated in the
bar and plate batch pickling rinse
processes. The spent pickling
solutions (HN01-HF and H2S04) are
disposed of by contract FauTer.
This plant utilizes equalization,
lime neutralization, and sedimen-
tation to treat waste water gener-
ation by the plate mill batch
pickling rinse process. The spent
waste pickle liquor is removed from
the plant to a company disposal site.
This plant utilizes municipal co-
treatment to treat process rinse water
generated by the batch bar pickling
operation. Waste pickle liquor
solutions are treated in plant utilizing
lime neutralization.
This plant utilizes municipal co-
treatment to treat process rinse waters
generated by the Kolene descaling process,
Once-through waste water from the
Kolene Quench Tank discharges to a
receiving stream without treatment.
Once-through waste water from the
Kolene Rinse Tank discharges to a
receiving stream without treatment.
WIRE PICKLING AND COATING
This plant utilizes equalization,
lime neutralization, chemical
coagulation, clarification, centri-
fuging, and recycle to treat waste
waters generated by the Bar and Wire
Batch Pickling rinse process and the
Copper, Lead, and Molybdate Coating
253
-------
Processes.
This plant utilizes municipal co-
treatment to treat process rinse
waters generated by the Wire Mill
Cleaning and Coating Operations.
Waste pickle liquor solutions are
treated in plant utilizing lime
neutralization.
This plant utilizes equalization,
sodium hydroxide neutralization,
aeration, chemical treatment, and
sludge lagooning to treat process
rinse water generated by the wire
batch pickling operation.
CONTINUOUS ALKALINE CLEANING
This plant utilizes sedimentation
to treat the waste water generated
by the Continuous Alkaline Cleaning
Process.
254
-------
with a low energy fixed orifice quencher. As the hot gases
exit from the hood, the gases are immediately quenched from
150°C to 85°C saturation temperature.
The aqueous discharge from the scrubber system is from the
primary quencher with the effluent being discharged to
thickeners. Most systems have thickeners for settling of
solids. Flocculation polymers systems are generally
installed to aid settling. The overflow from the thickener
is discharged to the plant sewers and the underflow from the
thickeners is passed through filters with the filtrate being
returned to the thickener while the filter cake is sent to
the sintering plant for recycling. These systems can become
recycling systems by adding make-up water to compensate for
water evaporation in the primary quencher.
Plant Vi sits
One basic oxygen plant was visited in the study. Detailed
descriptions of the plant waste water treatment practices
are presented on the drawing. Table 9 presents a summary of
the plants visited in respect to geographic location and
daily production of the facility. Table 88 presents the
plants' raw and effluent waste loads. Brief descriptions
and drawings of the individual waste water treatment systems
are as follows:
Plant D - Figure 27. This plant utilizes coagulation,
thickening, and discharge of the thickener originating from
the gas cleaning system.
VACUUM DEGASSING
The condensed steam and heated cooling water is discharged
from the barometric condenser in a hot well. The water from
the hot well is either discharged or is routed into a
combination water treatment system that services other
steelmaking facilities. The water rate for the barometric
condensers systems is approximately 20 - 41 gal/sec with
temperature increases of 20-30°C. Inert gases, for example
argon, are injected for mixing of bath and nitrogen is used
for purging the system before breaking the vacuum.
Plant Visits
Two degassing plants were visited in the study. Detailed
descriptions of the plant waste water treatment practices
are presented on individual drawings. Table 10 presents a
summary of the plants visited in respect to geographic loca-
255
-------
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tion and daily production of the facility. Table 89
presents the plants' raw and effluent waste loads.
Plant E - Figure 28. Vacuum degasser waste water on a
recycle loop with no continuous blowdown and periodic batch
system purges.
Plant G - Figure 29. Vacuum degasser waste water is on a
once-through system and discharged with no treatment.
CONTINUOUS CASTING AND PRESSURE SLAB MOLDING
The spray water system water discharge is an open
recirculating system with make-up and blowdown using either
settling chamber scale pits with drag link conveyors or flat
bed type filters for scale and oil removal. The effluent
from the scale pit or filtrate from the flat bed filters is
sometimes reduced in temperature by pumping through induced
draft cooling towers before recycling the waters back to the
spray system. Approximately 5-10% of the spray water is
evaporated during the spray of the cast product. The
aqueous discharge from this system is blowdown.
Plant Visits
Two continuous casting plants were visited in this study.
Detailed descriptions of the plant waste water treatment
practices are presented on individual drawings. Table 11
presents a summary of the plants visited in respect to
geographic location and daily production of the facility.
Table 90 presents the plants' raw and effluent waste loads.
Plant D - Figure 30. Caster waste water is on a moderately
tight recycle loop. The loop contains a sump, filter, and
clarifier. The system is batch purged weekly.
Plant 2 ~ Figure 31. Gross effluent waste loads are 19
gal/ton and 0.0026 Ib of suspended solids per 1000 Ib of
steel produced.
Pressure Slab Molding
The contact mold cooling water is a once-through system that
flushes the mold release agent to settling basins. The
relatively insoluble mold release material settles within
the basins and the basin effluent flows to a receiving
stream.
Plant Visits
261
-------
Table 90
Plant Raw S Effluent Waste Load
Continuous Casting and Pressure Slab Molding
Raw Waste Load
Plant
Parameters
Elow (gal/ton)
Susp. Solids
Fluoride
Oil £ Grease
pH (units)
D
Ib/ton
15
rag/1
Q '
Ib/ton
928
0.975
0.190
0.126
mg/1
126
24.5
16.3
8.9
B
Ib/ton
381
7.737
0.002
0.142
mg/1
2,435
.5
44.8
7.6
Range
Ib/ton
15-928
.975-7.737
.002-. 190
.126-. 142
mg/1
126-2435
.5-24.5
16.3-44.8
7.6-8.9
Effluent Waste Load
Parameters
Flow (gal/ton)
Susp. Solids
Fluoride
Oil & Grease
pH (units)
Ib/ton
3.3
0.116
0.002
0.0001
mg/1
4230
62
4.1
7.2
Ib/ton
19
0.020
0.004
0.003
mg/1
126
24.5
16.3
8.9 -
Ib/ton
381
0.359
0.001
0.051
mg/1
113
0.3
16.2
7.5
Ib/ton
3.3-381
.020-. 359
.001-. 004
.0001-. 051
,
mg/1
113-4230
.3-62
4.1-16.3;
7.2-8.9
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PROCESS: HOT PORMINS-PRIMARV
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HOT FORMING (Primary)
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One pressure slab irolding plant was visited in this study.
Detailed descriptions of the plant waste water treatment
practices are presented on the individual drawing. Table 11
presents a summary of the plants visited in respect to
geographic location and daily production of the facility.
Table 90 presents the plants' raw and effluent waste loads.
Plant B - Figure 32. Slab molding waste water is used on a
once-through system and pumped into settling basins and
discharged.
HOT FORMING - PRIMARY
Plant Visits
Five primary carbon plants were visited in the study. Table
12 presents a summary of the plants visited in respect to
geographic location, daily production, plant age, and age of
the treatment facility. Table 91 presents the plants' raw
and effluent waste loads.
Plant A-2 - Figure 33. Wastewaters from blooming and billet
mills are combined at this plant. The plant practices both
primary and secondary clarification followed by a series of
deep bed filters. Part of the clarifier overflow is
recycled to the mills. The filter effluent is discharged.
Plant B-2 - Figure 34. Blooming mill wastewaters are
treated by primary and secondary clarification followed by
deep bed filtration. The filter effluent is discharged to
the receiving
Plant C-2 - Figure 35. Blooming mill wastewaters are
treated via primary sedimentation followed by deep bed
filtration and recycle to a variety of plant water uses.
Plant D-2 - Figure 36. This plant combines blooming and
billet mill wastewaters for treatment. Oil skimming,
primary and secondary clarification are utilized followed by
deep bed filtration. Filter discharge is returned to intake
pumps for recycle and reuse in the mill.
Plant L-2 Figure 37. This plant uses primary clarification
including oil skimming, followed by chemical treatment,
vacuum filtration, and cooling with partial blowdown.
Treated water is reused in mill and elsewhere in plant as
makeup and noncontact cooling water.
280
-------
Plant Visits - Specialty Steel
Eight primary specialty steel plants were visited in the
study. Detailed descriptions of the plant wastewater
treatment practices are presented on individual drawings.
Table 12-A presents a summary of the plants visited in
respect to geographic location and daily production of the
facility. Table 91-A presents the plants' raw and effluent
waste loads.
Plant E - Figure 38. Once-through process waste water from
the Blooming and Universal Mills is combined and treated in
a flocculator-clarifier followed by deep-bed sand
filtration.
Plant H - Figure 39. This plant utilizes scale pit type
sedimentation to treat waste water generated by the Blooming
Mill.
Plant K - Figure 40. This plant utilizes scale pit
sedimentation, oil skimming equipment, and recycle with
approximately 14 percent blowdown to treat waste waters
generated by the Blooming Mill.
Plant R - Figure 41. This plant utilizes scale pit type
sedimentation and lagooning to treat waste water generated
by the Blooming Mill.
Plant D - Figure 42. This plant utilizes scale pit
sedimentation and oil skimming to treat waste water
generated by the Universal Mill.
Plant M - Figure 43. This plant utilizes sedimentation and
recycle with approximately 10 percent blowdown to treat
waste waters generated by the Blooming Mill. The blowdown
mixes with other waste waters, is cooled in a spray pond and
recycled to other processes.
Plant Q - Figure 44. This plant utilizes scale pit and oil
collection equipment to treat waste waters generated by the
Blooming Mill. The waste waters mix with other waste waters
before the scale pit.
HOT FORMING - SECTION
Plant Visits
Seven carbon steel section operations containing ten
production units were visited in the study. Table 13
presents a summary of the plants visited in respect to
281
-------
geographic location, daily production, plant age, and age of
the treatment facility. Table 92 presents the plants' raw
and effluent waste loads.
Plant A-2 - Figure 33. Wastewaters from blooming and billet
mills are combined at this plant. The plant practices both
primary and secondary clarification followed by a series of
deep bed filters. Part of the clarifier overflow is
recycled to the mills. The filter effluent is discharged.
Plant D—2 - Figure 36. This plant combines blooming and
billet mill wastewaters for treatment. Oil skimming,
primary and secondary clarification are utilized followed by
deep bed filtration. Filter discharge is returned to intake
pumps for recycle and reuse in the mill.
Plant E-2 - Figure 45. This plant utilizes primary settling
o5wastes from two mills, followed by secondary
clarification, sand filtration, cooling, and recycle back to
mills. Slowdown from system is less than 4%.
Plant F -2 - Figure 46. This plant practices primary and
secondary clarification including oil skimming. Portion of
effluent is returned as flushing and coil cooling water.
Remainder is discharged to a central treatment system
undergoing vacuum filtration, chemical treatment, and
cooling with discharge of cooling tower blowdown.
Plant G-2 - Figure 47. This plant utilizes primary and
secondary clarification~Tncluding oil skimming on two mills,
followed by sand filtration, cooling, and total recycle.
Plant H-2 - Figure 48. The plant scale pit effluent is sent
to cyclonic solids separator with clarified water discharged
to receiving stream.
Plant 1-2 - Figure 49. All wastewaters from this plant are
discharged to a terminal treatment lagoon.
Plant Visits - Specialty Steel
Seven section hot forming plants were visited in the study.
Detailed descriptions of the wastewater treatment practices
are presented on individual drawings. Table 13 presents a
summary of the plants visited in respect to geographic
location and daily production of the facility. Table 92-A
presents the plants' raw and effluent waste loads.
Plant C - Figure 50. This plant utilizes a cooling
reservoTr equipped wTth an oil skimmer and recycle to treat
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waste waters generated by the Bar Mill. Other waste waters
mix with this waste water in the reservoir.
Plant H - Figure 51. This plant utilizes scale pit type
sedimentation to treat waste water generated by the Merchant
Mill.
Plant K - Figure 52. Once-through process waste water
generated by the Bar Mill discharges directly to a receiving
stream with minor recycle.
Plant M - Figure 53. This plant utilizes sedimentation and
recycle with blowdown (approximately 21 percent) to treat
waste waters generated by the Billet Mill. The blowdown
mixes with other waste waters, is cooled in a spray pond and
recycled to other processes.
Plant 0 - Figure 54. This plant utilizes sedimentation and
recycle with approximately 6% blowdown to treat waste waters
generated by Hot Rolling Mills.
Plant Q - Figure 55. This plant utilizes scale pit and oil
collection equipment to treat waste waters generated by the
Bar Mills. The waste water mixes with other flows before
the scale pit.
Plant R - Figure 56. This plant.utilizes scale pit type
sedimentation and lagooning to treat waste water generated
by Bar Mills.
Plant OJ_ - Figure 57. This plant utilizes scale pit type
sedimentation and recycle with blowdown (approximately 2.5
percent) to treat waste water generated by five Rod Mills.
HOT FORMING FLAT
Visits were made to five carbon and three specialty steel
plants in this subcategory. Table 14 presents a summary of
the plants visited in respect to geographic location, daily
production, plant age, and age of the treatment facility.
Tables 93 and 93-A present the plants' raw waste and
effluent loads.
Plate Mills
Plant K-2 - Figure 58. This plant practices primary and
secondary clarification, filtration, cooling, and recycle
for mill use. Blowdown from system is approximate 3%.
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Plant F - Figure 59 This plant utilizes scale pit type
sedimentation to treat waste water generated by the Plate
Mill.
HOT STRIP AND SHEET MILLS
Plant Vi si ts
Plant J-2 - Figure 60. This plant utilizes primary and
secondary clarification, chemical treatment, gravity
filtration, and discharge to the receiving stream.
Plant L-2 - Figure 61. This plant uses primary
clarification including oil skimming, followed by chemical
treatment, vacuum filtration, and cooling with partial
blowdown. Treated water is reused in mill and elsewhere in
plant as makeup and noncontact cooling water.
Plant M-2 - Figure 62. This plant utilizes primary
clarification including oil skimming, following by chemical
treatment, clarification, filtration, and discharge to
receiving stream.
t
Plant N-2 - Figure 63. This plant practices primary
clarification, high flow sand filtration, cooling, and total
recycle to mill.
Plant E - Figure 64. Once-through process waste water from
the Hot strip Mill is treated in a flocculator-clarifier
followed by deep-bed sand filtration.
Plant D - Figure 65. Once-through process waste water
generated by the Hot Strip Mill mixes with other waste water
flows and discharges to a receiving stream without
treatment.
PIPE AND TUBE MILLS - HOT WORKED
Plant Visits
Visits were made to five hot worked pipe and tube mills.
Table 15 presents a summary of the plants visited in respect
to geographic location, daily production, plant age, and age
of the treatment facility. Table 94 presents the plants'
raw waste and effluent loads.
Plant E-2 - Figure 45. This plant utilizes primary settling
of mill wastes followed by secondary clarification, sand
filtration, cooling, and recycle for use by two hot forming
311
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section mills. Slowdown from the overall system is less
than 4%.
Plant GG-2 - Figure 66. This plant utilizes primary
sedimentation, oil separation, and recycle to pond for mill
use.
Plant II-2 - Figure 67. Wastewaters at this plant are
treated by, sedimentation, oil skimming, filtration, final
settling lagoon, and discharge to receiving stream.
Plant JJ-2 - Figure 68. Wastewaters at this plant are
treated by primary sedimentation, mixing with acid rinses,
lagooned for evaporative cooling, and recycled for plant
reuse.
Plant KK-2 - Figure 69. This plant practices primary and
secondary sedimentation, oil separation, polyelectrolyte
addition, and discharge to receiving stream.
PIPE AND TUBE MILLS - COLD WORKED
Plant Visits
A visit was made to one cold worked pipe and tube mill.
Table 15 presents a summary of the plant visited in respect
to geographic location, daily product, plant age, and age of
the treatment facility. Table 94 presents the plants' raw
waste and effluent loads.
Plant HH-2 - Figure 70. This plant has an excellent total
recycle system. Wastewaters are settled in ponds and then
returned to reservoir for process reuse throughout the
plant.
PICKLING
Several different treatment systems have been used
throughout the years in dealing with the liquid discharges
associated with the pickling process. They may be grouped
into two general classes: disposal processes; and recycling
processes.
Disposal Processes
1. Dumping to a waterway
2. Dumping on an alkaline bed
3. Contract hauling
U. Dumping into municipal treatment facilities
5. Simple neutralization
319
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6. Modified neutralization
7. Controlled neutralization/oxidation
8. Deep well disposal
None of these methods offers the ideal answer for the
treatment of this wastewater.
Dumping, hauling, and deep well injection move the
contaminants from one place to another and, therefore, only
relocate the pollution problem. Neutralization destroys
valuable materials which could have been recycled.
It also will produce a sludge or semi-solid which, when
improperly handled, can cause serious land pollution
problems. In addition, many neutralized discharges contain
high concentrations of dissolved solids, usually sodium or
calcium sulfate or chlorides.
However, in relation to one another, each has its advantages
and disadvantages. Each method deserves separate
discussion. Ml are pontentially subject to regulation by
permit authorities on local or national level.
Dumping to a Waterway. This method includes dumping
directly or indirectly into streams, rivers, lakes,
including barging or piping to sea.
Disadvantages. Water pollution and community objections.
This method simply moves the pollutant from one place to
another. No recovery of products.
Advantages. Low investment cost. Low operating cost.
Remarks. The dissolved iron salts are more objectionable in
most cases than the free acid. The iron causes a brown
discoloration of the water and objectionable slime deposits.
Ferrous iron exerts a high oxygen demand, which totally
depletes the dissolved oxygen of the receiving stream.
Dumping on an Alkaline Bed. This method includes dumping
onto piles of oyster shells, steel mill slag, or other
alkaline materials.
Disadvantages. Only part of the free acid is normally
neutralized and the dissolved iron runs off. No recovery of
products.
Advantages. No investment cost. Low operating cost.
320
-------
Remarks. The pollution problem of color and slime from iron
remains unsolved. Free acid and dissolved iron can
contaminate ground waters or surface waters.
Contract Hauling. It is assumed that this method includes
the subsequent proper treatment of the waste by the contract
hauler. Therefore, the cost would include hauling
(transportation) and treatment.
Disadvantages. High unit cost. Contract hauling costs
generally range upwards from $0.03 per gal. The producer of
the waste remains legally responsible for the manner of
ultimate disposal and any resultant pollution. No recovery
of products.
Advantages. Low investment cost. This is frequently the
least expensive method of disposal for small volumes of
waste if the contractor is reliable and applies approved
treatment technology.
Remarks. The producer is directly dependent upon the
reliability of the contract hauler.
Dumping into Municipal Treatment Facilities. Some pickling
operations dump their liquid discharges, either treated or
untreated, directly into municipal sewer systems.
Disadvantages. Limited to small quantities. Waste pickle
liquor generally has to be partially neutralized with soda
ash, caustic soda or ammonia. In some cases, could impose
unnecessarily excessive loads on the municipal system. No
recovery of products.
Advantages. Low investment cost. Modest operating cost.
Remarks. Neutralization of the free acid, but not the
ferrous sulfate, will generally be required.
Simple Neutralization. A commonly used treatment is
neutralization of the spent pickle solutions with treatment
chemicals. This approach is intended to raise the pH to
about 7, so that a neutral liquid can be discharged.
Disadvantages. Problems arise in the disposal of the
resultant sludge. Ferrous hydroxide in the neutralized
mixture is extremely difficult to settle and the sludge must
be pumped into lagoons where it has to be kept indefinitely.
This is no small problem. The pickling of 1,000,000 tons of
steel can result — if neutralization is used on the spent
liquor — in the production of 200,000 tons of sludge that
321
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will not dewater. The sludge requires 150 acre feet of
permanent fill volume and high freight or real estate costs.
Simple neutralization may cost from $0.02 to $0.05 per gal.
No recovery of products.
Advantages. Low to medium cost initial investment.
Operating cost is usually less expensive than contract
hauling for large volumes.
Remarks. Simple neutralization techniques will probably not
meet the future effluent discharge standards as far as
dissolved solids are concerned, especially iron.
Modified Neutralization. This method is simple
neutralization plus the filtration of the resultant iron
hydroxide sludge.
Disadvantages. Medium to high investment costs. High
operating costs. Increased operating complexity. No
recovery of products.
Advantages. Some water can be sewered, thus reducing sludge
freight.
Remarks. Filter cake contains 1 to 2 Ib of water per Ib of
solids and is slow drying unless spread over a large area.
Runoff or seepage from filter cake dumping ground will
contain iron contaminants.
Controlled Neutralization/Oxidation. This method is more
acceptable than simple neutralization because it neutralizes
the solution to a pH of 7 to 9, and then oxidizes the
resultant ferrous hydroxide to magnetic iron oxide
(magnetite) and water. Thus, the usual hydroxide sludge
problem is avoided.
Disadvantages. High investment cost. High operating cost.
Increased operating complexity, requiring sophisticated
process and equipment. High temperature and relatively long
retention time required in the process.
Advantages. Easy-to-dewater solids. Sludge weight
one-sixth (1/6) that of simple neutralization. Recoverable
magnetic iron oxide. Solids make good landfill.
Remarks. Solids can be centrifuged to moist earth
consistency, or slurry can be piped directly to a natural
drainage area for accumulation of solids and decantation of
excess water.
322
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Well Disposal. There are several hundred deep
injection wells in the United States, but only a dozen or so
are used to dispose of waste pickling liquors. Depending
upon local conditions and geology, some of these are
relatively troublefree in operation and maintenance, and
some are extremely troublesome.
Disadvantages. Great depth needed to minimize chance of
pollution problems by contaminating ground waters. Medium
to high initial investment. Precise filtration required
prior to injection. No recovery of products. Rapidly being
controlled or limited by local, state, and federal
regulations.
Advantages. Elimination of neutralizing costs. Low
operating cost. Versatility.
Remarks. Highly dependent on local geology. Great risk is
involved because the contaminants may penetrate waterbearing
strata. Great care must be taken to avoid pumping too high
a solids concentration into the porous starta because it
would be very easy to block the strata and force the well to
shut down.
Recycling Processes
The only really effective method industry can use to stop
pollution is to eliminate discharges from a particular plant
or operation. By attacking waste at its source, the
potential may exist where pollution control can be converted
from a non-productive expense to a cost-cutting, perhaps
even profitable, investment.
Any comprehensive solution to this complex problem must
simultaneously resolve all related difficulties at one time
and in one system. Many attempts have been made in the past
to cope with these effluent problems. They have often
failed because of inability or refusal to comprehend these
separate problems as interdependent aspects of one complex
problem.
Conservation by recycling in a "closed-loop" system is an
answer. This will minimize the cost and volume of
effluents, stop waste and inefficiency, and eliminate
discharges of noxious materials from pickling plants. In
this way, scale removal operations may become less costly
and pollution free.
The system should be simple and easy to operate, corrosion
resistant and mechanically sound and, most important, be
323
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economically viable. Such systems are available and have
been proven effective in many pickling operations.
Sulfuric. Most common is acid recovery through removal of
ferrous sulfate by crystallization. Spent pickle liquor
high in iron content is pumped into a crystallizer where it
is cooled, and the iron is crystallized as ferrous sulfate
heptahydrate. The crystals are then separated, and the
remaining (recovered) acid is pumped back to the pickling
tank. The discharge from the system is ferrous sulfate
heptahydrate in pure, crystalline form, a chemical byproduct
with commercial value. Sale of this chemical may offer
potential income where market conditions permit. The
crystals are dried, bagged, and marketed, or sold in bulk
quantities. Ferrous sulfate, commonly referred to as
"copperas," is used in appreciable quantities in numerous
industries, with its most important value in the manufacture
of inks, dyes, paints, and fertilizers. Its use as a
flocculating agent in waste treatment and sewage plants is
exceptionally noteworthy because the demand for this
chemical increases constantly as municipal sewage plants
improve and expand their treatment facilities.
Hydrochloric. The only existing commercially proven
technology at this time for the regeneration of acid from
spent hydrochloric acid pickling solutions is through
thermal decomposition. The spent pickle liquor contains,
essentially, free hydrochloric acid, ferrous chloride, and
water. This liquor is generally first heated so that
evaporation removes some of the water and thus concentrates
the solution. The concentrated solution is subjected to
temperatures of about 925° to 1,050°C (1,700° to 1,920°F).
At this temperature, evaporation and decomposition takes
place. Water is further evaporated and the ferrous chloride
decomposes into iron oxide and hydrogen chloride. The iron
oxide is separated and removed from the system. The
hydrogen chloride gas is reabsorbed into water (sometimes
rinse water or scrubber water is used) , thus making a
reusable hydrochloric acid solution. There are several
types of these "roaster" processes available and in
operation throughout the world. The basic difference
between the processes is the design and operation of the
roaster/reactor itself. Each different design, however,
seems to have its own distinct advantages and disadvantages
associated with it.
Crystallization Processes (Sulfuric .Acid)
Continuous Type. There are three acid recovery plants in
North America (two in Canada, one in the U.S.A.) at this
324
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time employing a continuous vacuum crystallization process.
Spent pickle liquor with high iron content is precooled and
continuously pumped to a multi-stage crystallizer where it
is further cooled by evaporation in a vacuum maintained
through high pressure steam ejectors and a mechanical vacuum
pump. The acid/crystal slurry is pumped to a concentrator
and from there to a centrifuge for crystal separation. The
recovered acid is then returned at about 10° to 16°C (50° to
60°P) to the pickling tanks. Regular operator attention is
required and a consistent composition of spent pickle liquor
is required for its optimum and practical operation.
In order to maintain continuous operation of the vacuum
crystallizers, it is necessary to supply those units with a
continuous supply of consistent pickle liquor. This then
involves the necessity of adequate storage tanks at each end
of the recovery system.
The continuous type process is illustrated in Figure 71.
Batch Type. This process is in successful operation in 17
plants throughout the North American continent on both
continuous and batch pickling lines, handling strip, sheets,
rods, wire, bar, and other product configurations. In each
case, pickling costs were reduced significantly. The oldest
such system has been in operation for over seven years. See
Figure 72.
The heart of the system is a batch type crystallizer where
spent pickling liquor is agitated and cooled through a
recirculating chilled water circuit. After separation of
crystals by decanting, the recovered acid is reheated to 60°
to 65°C (140° to 150°F) prior to return to the pickling
tank. The plant is very simple and does not require
continuous operator attention.
Acid entrained in the pickling tank exhaust system is
removed in the acid mist filter and rinse water is reused in
the pickling tank. The system then has "zero liquid
discharge."
Where the batch crystallizer is to be used in conjunction
with pickling lines that discharge pickle liquor on a
continuous basis, or those that dump many various batches of
liquor at indeterminate times, a "conditioning holding tank"
is added to the system.
This pickling and acid recovery system offers many
advantages and features: (a.) purchased acid consumption
reduced as much as SOX; (b.) it allows recovery and reuse of
325
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326
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significant amounts of inhibitors; (c.) eliminates costs and
problems of disposing of spent pickle liquors, rinse waters,
and scrubber waters; (d.) shows savings in water costs in
rinsing and scrubbing by direct recovery of all of the rinse
water (and the acid in it); (e.) it can also offer increased
production because of constant optimum pickling conditions;
(f.) it lowers operating costs through the simplicity of the
system (does not require constant operator attention); (g.)
minimizes delay in dumping and making up acid tanks; (h.)
eliminates environmental problems indoors and pollution
problems outdoors by recovering acid from mist; (i.) trims
load on municipal sewers and sewage plants; finally, (j.)
most important, it ends water pollution from pickling.
Hydrochloric Acid Regeneration
The available commercially proven processes under this
category are essentially the same, in that each heats the
pickle liquor to relatively high temperatures in thermal
reactors. At these high temperatures, decomposition occurs
yielding iron oxide (ferric oxide, Fe^O3) , water (vapor) ,
and hydrogen chloride (HC1) gas. Water vapor is scrubbed
prior to discharge to atmosphere. Iron oxide particles are
separated and discharged from the system. The hydrogen
chloride gas is absorbed into water which produces a
"regenerated" hydrochloric acid solution, generally from 15X
to 21% HCl (by weight). The regenerated acid is then
recycled back into the pickling operation.
The two variations of this process that are noteworthy are:
Spray Roaster Type Process. This process incorporates a
relatively large roaster vessel which is heated to about
1,000°C (1830°F) .
Pickle liquor is pumped at high pressure through filters to
the top of each spray roaster, entering through four spray
heads, which atomize the pickle liquor. Four natural gas
burners, arranged symmetrically around the circumference of
the roaster, heat the atomized pickle liquor as it descends
in the roaster. As the temperature of the liquid rises, the
water and free HCl vaporize yielding steam and hydrogen
chloride gas while the iron chloride is converted to iron
oxide and hydrogen chloride gas. The relatively heavy iron
oxide drops down into the cone of the roaster while the
water vapor, hydrogen chloride gas, and products of
combustion rise.
To draw the hydrogen chloride gas frcm the roaster, negative
pressure is created by exhaust fans installed in series.
328
-------
The system is made negative to prevent the escape of
hydrogen chloride gas should a leak develop in the piping
system.
some of the iron oxide particles are very fine and are
carried off the top of the roaster with the discharged
roaster gases. These particles are removed by a cyclone
installed in the system immediately after the roaster.
The cyclone is located on an elevated platform directly over
the oxide storage hopper so that the fine particles of iron
oxide fall directly into the storage bin. This arrangement
eliminates the difficult problem of conveying these
microscopic particles.
To convert the gas to HCl acid, it is passed through an
absorber, consisting of a brick lined shell with a carbon
grill and ceramic saddles.
The steam and gas enter the bottom and rise through the
grill while the water percolates down, condensing the steam
and converting the gas to HCl acid. The non-soluble
products of combustion go up the stack.
Water is metered to the absorber to produce 2096 HCl (by
weight). Details of this process are presented on Figure
73.
Fluid-Bed Roaster Type. This is basically the same type of
process as the spray roaster type except that the reactor
vessel itself is relatively smaller in size than a
comparable spray roaster. This is possible because the
roaster vessel contains a fluid bed which allows longer
retention times because of the bed itself.
Because of the nature of this process using the fluid bed,
the resultant iron oxide leaves the system as a small pellet
instead of a dust.
Vital plant components are the reactor, a cyclone, a pre-
evaporator/venturi scrubber combined with a separator, and
an absorber.
The spent pickle liguor to be regenerated is delivered into
the combined pre-evaporator/venturi scrubber in which it is
concentrated, utilizing the waste heat recovered from the
hot gases emitted from the reactor.
The concentrate is subseguently charged into a fluidized bed
of granular ferrous oxide maintained at about 800°C.
329
-------
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330
-------
Evaporation of the residual water and decomposition of the
ferrous chloride takes place simultaneously. The major
portion of Fe2O3 clings immediately to the surface of the
hot fluidized grains. A residence time of several hours in
the bed assures adequate grain growth to a range of 0.2-
2.2 mm diameter. The reactor is controlled to a constant
fluid bed level.
A small amount of Fe£O3 that has not taken part in the grain
growth is carried over and subsequently collected in the
cyclone and recharged to the reactor. Hot gases leaving the
reactor contain hydrochloric acid gas, superheated water
vapor, combustion products of the heating medium, and a
small amount of ultrafine dust. The dust is washed out in a
high-efficiency venturi scrubber. These fines are dissolved
in the pickle liquor feed stream and recycled.
After separation from the liquor, the cooled HCl-bearing
gases pass into an absorber charged with water (possibly
rinse water), in which acid below the azeoptropic
composition is recovered by adiabatic absorption. Most of
the commercial plants built so far produce 10-12% acid,
although some go as high as 1855. The vapors issuing from
the absorber are discharged via a suction fan that maintains
the entire plant under negative pressure.
Acid recovery efficiency is over 99.5%, with losses being
confined to small quantities in the waste gas. There is
almost a complete absence of iron in the regenerated liquor.
The small amount of dust from the reactor that could
otherwise contaminate the pickle liquor is separated in
high-efficiency collectors, thus resulting in optimum
conditions for pickling.
Fuel is burned directly in the fluidized bed. Rugged
structural elements permit direct and complete burning;
separate combustion chambers are not needed, which
simplifies the design and saves on cost.
Bulk density of the pelletized iron oxide product is 2920-
3570 kg/cu m. (180-220 Ib/cu ft). The pellets retain their
shape even in the presence of water and during handling and
storage. Chlorine composition is 0.02%. Details of this
process are presented on Figure 74.
Other processes that are currently under research
development or demonstration include the following:
Sulfuric Acid Process. A system has been demonstrated at
pilot plant level which utilizes a process well known in
331
-------
332
-------
Europe. This process is a "heating" process rather than the
more common and proven "cooling" processes. The process, in
effect, heats spent pickle liquor to about 150° to 175°C
(302° to 347°F), at which time fresh acid is added to bring
the acid concentration to about 50% to 5556 H.2SCW (by
weight). At this point, the ferrous sulfate content of the
pickle liquor precipitates as ferrous sulfate monohydrate
(crystals). Details of this process have not been made
available at this time.
Hydrochloric Acid Processes. A pilot plant has been
developed and demonstrated and is now in the process of
being moved to a commercial operation. This process is a
thermal decomposition type process but claims a unique
roaster reactor which is neither the "spray roaster" design,
nor the "fluid-bed" design. The reactor is a "sliding-bed"
type unit which produces a "sintered" agglomerate of iron
oxide, and requires only a relatively small reactor in
comparison to the other types of roasters.
A wet chemical process is also in development at this time.
It has been proven in the laboratory, pilot plant, and
demonstration plant level.
Waste pickle liquor is concentrated by thermal evaporation
and then air oxidized, under pressure, to produce a solution
of ferric chloride and some iron oxide. This solution is
then hydrolyzed to produce HCl gas and iron oxide. HC1 is
recovered in an absorbing tower. The iron oxide that is
produced can be recycled, used commercially, or disposed of
as a non-polluting solid.
Waste pickle liquor storage provides a means of reserve to
even out the flow and the composition of the waste pickle
liquor. The pickle liquor is pumped to the evaporator where
the solution is concentrated. This concentrated solution is
fed to the oxidizer, which converts the ferrous chloride in
the waste pickle liquor to ferric chloride. From the
oxidizer the ferric chloride solution is blown over to the
hydrolyzer, where hydrolysis of the ferric chloride takes
place and black ferric oxide and hydrogen chloride gas are
produced. The hydrogen chloride gas is absorbed in an
absorber to produce hydrochloric acid at a concentration
between 20-31%, depending on feed composition. The iron
oxide is separated in the recovery system consisting of a
wet separator, a slurry tank, a vacuum filter, and a
conveyor system for ferric oxide disposal. The process flue
gases are scrubbed in a tail gas scrubber. The process
provides the steel industry with unique operational
capability. Waste pickle liquor can be concentrated, or
333
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334
-------
oxidized to produce sewage grade ferric chloride, or
processed -to produce a high strength hydrochloric acid
solution. The iron oxide produced is a dense non-polluting
material which can be recycled to the steelmaking operation,
sold as a commercial product, or disposed of as a non-
polluting solid. Details of this process are presented on
Figure 75.
Plant Visits
Visits were made to 15 plant locations covering the various
subcategories of pickling. Tables 16, 16-1 and 17 present
the summary of the plants visited in respect to geographic
location, daily production, plant age, and age of the
treatment facility.
Batch Sulfuric
Tables 95 and 96 present the plants' raw and waste effluent
loads.
Plant 1-2 - Figure 49. Waste pickle liquor hauled away by
private contractor. All rinses are combined with other mill
wastes in a terminal lagoon and discharged to a canal.
Plant O-2 - Figure 76. Plant utilizes batch evaporative
crystallization of spent sulfuric acid. Acid recovered with
production of ferrous sulfate heptahydrate. Rinses are
recycled to process as makeup to pickle tank.
Plant P-2 - Figure T7 and 78. Plant utilizes batch pickle
liquor regeneration by vacuum crystallization. Rinses are
metered to the sewer.
Plant Q-2 - Figure 79. Plant practices batch pickle
regeneration through cooling of spent pickle liquor and
precipitation of ferrous sulfate heptahydrate. Rinses and
mists from filter are recycled back to pickle tank.
Plant R-2 - Figure 80. Plant combines pickle liquor and
rinses in an equalization tank, flash mixes amd treats with
acetylene sludge, lagoons, and discharges to receiving
stream.
Plant S-2 - Figure 81. Concentrated pickle liquor is
contract hauled. Standing rinse is reused as makeup to
pickle tank. Running rinse is treated with lime and
lagooned. Lagoon overflow is recycled, and sludge is
contract hauled.
335
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Table 96-A
Plant Raw and Effluent Waste Loads
Pickling - Sulfuric Acid - Batch - Specialty Steel
Plant R
Plant Raw Waste Load
Parameters
Flow (gal /ton)
Susp. Solids
Oil & Grease
Diss. Iron
pH (units)
Ib/ton
30
0.041
0.0003
2.250
mg/1
162
1.3
8991
1.6
Plant Effluent Waste Load
Parameters
Flow (gal/ton)
Susp. Solids
Oil & Grease
Diss. Iron
PH
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WASTEWATtlR TREATMENT
WATER FLOW DIAfeRAM
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Plant Visit - Specialty Steel
A visit was made to one plant which was clearly identifiable
as having this type of pickling operation alone.
Plant R - Figure 81-A This plant utilizes lime
neutralization and sludge lagooning to treat both the rinse
water and waste pickle liquor solutions generated by the
batch pickling process. Table 16 presents a summary of the
plants visited in respect to geographic location and daily
production of the facility. Table 96-A presents the plants'
raw and effluent waste loads.
Continuous Sulfuric
Table 16 presents a summary of the plants visited in respect
to geographic location, daily production, plant age and age
of the treatment facility.
Tables 97-1r 97-2 and 97-3 present the plants' raw and waste
effluent loads.
Plant T-2 - Figure 82. Concentrated pickle liquor is
regenerated by evaporative concentration. Rinses are
recycled back as makeup to pickle tank. Steam condensate
serves as final rinse.
Plant E-2 - Figure 83. Concentrated pickle liquor collected
and hauled away for contract disposal. Process rinse water
collected and discharged to terminal treatment plant for
chemical addition, oil skimming, settling and discharge to
receiving stream.
Plant QQ-2 - Figure 84. Concentrated waste pickle liquor
collected, filtered and discharged to deep well. Fume
scrubber and process rinse water discharged to terminal
treatment plant for equalization, chemical addition,
flocculation, oil skimming, clarification and discharge to
receiving stream.
Plant SS-2 - Figure 85. Concentrated pickle liquor
collected and discharged directly to receiving stream. Fume
scrubber and process rinse water discharged to terminal
treatment plant for chemical treatment, aeration, oil
skimming, settling and discharge.
Plant TT-J - Figure 86. Concentrated waste pickle liquor
collected for batch lime neutralization, settling and
evaporation. Fume scrubber and process rinse water combined
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with other plant wastewaters and discharged directly to
receiving stream.
Plant WW-2 - Figure 87. Concentrated pickle liquor
collected, filtered and discharged to deep well. Fume
scrubber and process rinse waters discharged to terminal
treatment plant for aeration, oil skimming, settling and
discharge to receiving stream.
Batch Hydrochloric
Table 17 presents a summary of the plants visited in respect
to geographic location, daily production, plant age and age
of the treatment facility.
Tables 98 and 99 present the plants' raw and waste effluent
loads.
Plant U-2 - Figure 88. Waste pickle liquors and rinse
waters are neutralized in a batch treatment tank by sodium
carbonate prior to sanitary sewer discharge.
Plant V-2 - Figures 89 and 90. Spent pickle liquor is
contract hauled. Rinses are neutralized with NaOH prior to
sanitary sewer discharge.
Continuous Hydrochloric
Table 17 presents a summary of the plants visited in respect
to geographic location, daily production, plant age and age
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Tables 98 and 99 present the plants' raw and waste effluent
loads.
Plant 1-2 - Figure U9. Plant dilutes concentrated pickle
liquor and rinses with other mill wastes in a terminal
lagoon and discharges to a canal.
Plant W-2 - Figure 91. Waste pickle liquor is treated by
pyrolytic regeneration of hydrochloric acid. Rinses and
fume hood scrubber wastes are diluted and metered to the
sewer. Absorber vent scrubber treated with caustic solution
and discharged.
Plant X-2 - Figures 92 and 93. Plant practices spent acid
recovery via hydrochloric acid regeneration. Rinses are
diluted and metered to the sewer. Absorber vent scrubber
treated in clarifier with other plant wastewaters.
360
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Plant Y-2 - Figures 94 and 95. Waste pickle liquor is
treated by pyrolytic regeneration of hydrochloric acid.
Rinses and absorber vent scrubbers are diluted and metered
to the sewer.
Plant Z-2 - Figure 96. Plant treats waste pickle liquor and
rinses jointly via equalization, neutralization, aeration
and clarification with polymer addition, followed by
discharge to a sanitary sewer.
Plant AA-2 - Figure 97. Plant uses cascade rinse system
with rinses and concentrated pickle liquor disposed of via
deep well disposal.
Plant BB-2 - Figure 98. Concentrated pickle liquor is
disposed via off-site contract hauling or deep well
disposal. Rinses are equalized, mixed with cold mill
wastes, neutralized, aerated, treated with polymers,
clarified, lagooned, and discharged to a receiving stream.
COLD ROLLING OPERATIONS
Several different treatment systems have been used
throughout the years to treat wastewaters resulting from
cold rolling operations. These systems have progressed from
direct discharge to the receiving stream without treatment
to the treatment and reuse of the wastewater with no direct
discharge to the receiving stream. The high cost of rolling
oils, and the promulgation of regulations requiring
pollution control have all but eliminated the once-through
direct discharge of these wastes. Oil recovery systems and
closed-loop recycle systems are widely utilized for the
recovery and reuse of rolling oils. Oil is the major
pollutant in these wastes and all treatment systems are
primarily designed for its removal. The various treatment
systems are listed here according to the degree of treatment
they provide.
1. The simplest attempt to remove the oil from cold rolling
wastewater was to divert the water through a scale pit.
Free floating oil was removed ty a skimmer, some oil would
adhere to the scale and settle and the emulsified oils
passed through the pit and were discharged to the receiving
stream.
2. Oil separators specifically designed for the removal of
the particular rolling oil replaced the scale pit, with some
attempt to break the emulsions and remove as much of this
oil as possible. Emulsified oils were still discharged to
the receiving stream in significant quantities.
376
-------
3. A refinement to Step 2 to include chemical addition,
flocculation, air flotation, and surface skimming followed
by discharge to the receiving stream.
4. Utilization of spent pickle liquor to acidify the
wastewater and break the emulsion. The oil is removed by an
oil separator. The water is neutralized with lime, mixed
with other mill wastewater and clarified prior to
discharging to the receiving stream. Some mills discharge
the clarified water into a retention lagoon prior to
discharging to the receiving stream.
5. Another modification to the aforementioned system is to
collect the spent rolling oil emulsions in a storage tank
along with other oil-bearing wastewater generated in the
cold rolling operation. Some floating oil is removed in
this tank. The wastewater from the tank is metered to a
mixing tank where spent pickle liquor is added to break the
emulsion. The wastewater then goes to an oil separator to
remove the oil. The treated wastewater is then returned to
the mill water system and used as makeup water to the gas
cleaning system.
Plant Visits
Visits were made to five cold rolling operations. Table 18
presents summary of the plants visited in respect to
geographic location, daily production, plant age, and age of
the treatment facility. Table 100 presents the plants' raw
and waste effluent loads.
Plant SS-2 - Figure 85. This plant utilizes oil recovery
with wastewater effluent discharged to terminal treatment
plant for chemical treatment, aeration, oil skimming,
settling, and discharge.
Plant X-2 - Figure 92. This plant utilizes a combined
treatment system for cold rolling and pickling wastewaters.
Treatment system consists of air flotation, chemical
treatment, clarification, and plant reuse.
Plant BB-2 - Figure 98. This plant combines cold mill
wastewater with acid rinse waters, utilizing neutralization,
aeration, clarification with polymer addition, lagooning,
and discharge to the receiving stream.
Plant DP-2 - Figure 99. This plant practices oil skimming,
chemical treatment, sedimentation, and discharge to the
receiving stream.
377
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PROCESS: COLD ROLLING- coi
PLANT: VY-E
PRODUCTION : 3fal3 METRIC TOW
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WASTEWATER TREATMENT S/Y
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385
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Plant EE-2 - Figure 100. Plant wastewater treatment
practice includes equalization, oil skimming, chemical
treatment, lagooning, and sewer discharge.
Plant FF-2 - Figure 101. Wastewaters are treated by primary
sedimentation, mixing, chemical treatment, and discharge to
sewer.
Plant VV-2 - Figure 102. This plant utilizes oil recovery
with wastewater effluent discharged to sedimentation,
equalization, oil skimming and discharge to receiving
stream.
Plant YY-2 - Figure 103. This plant utilizes discharge of
cold rolling mill wastewater to terminal treatment plant for
oil skimming, settling, clarification and discharge to
receiving stream.
Plant XX-2 - Figure 104. This plant utilizes discharge of
cold mill wastewater to terminal treatment lagoons for
common mixing ohter plant wastewaters, aeration, settling,
oil skimming and discharge to receiving stream.
Plant Visits-Specialty Steel
Visits were made to three (3) cold-rolling operations.
Detailed descriptions of the various waste water treatment
practices are presented on individual drawings. Table 18
presents a summary of the plants visited in respect to
geographic location and daily production of the facility.
Table 100-A presents the plants' raw and effluent waste
loads.
Plant D - Figure 105. This plant utilizes oil skimming to
removing the insoluble surface oil and chemical addition to
break the emulsion for further separation to treat the
blowdown coolant from the cold rolling operation.
Plant _! - Figure 106. This plant utilizes oil skimming to
remove the insoluble surface oil and a paper filter to
remove particulate matter before recirculating the coolant
to the cold rolling process. The skimmed oil is reprocessed
by an outside firm. There is no other discharge from this
system.
Plant P - Figure 107. This plant utilizes a paper filter to
remove particulates from the coolant before it is
recirculated to the cold rolling process. There is no
discharge from this system. The entire volume is removed
periodically and reprocessed.
386
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COATING OPERATIONS
A wide variety of ways to handle coating wastes exist
throughout the steel industry, and yet certain basic
treatment systems are commonly used much more than others.
These are listed here according to the degree of treatment
they provide.
1. No matter what wastewater treatment technique, if any,
is used, an important first step is to minimize the quantity
of wastes requiring treatment. This is accomplished by
providing dragout recovery tanks downstream of the main
cleaning tanks; by utilizing high pressure spray rinses with
recycling of rinse waters where practical; and by careful,
even critical, attention to maintenance of equipment such as
rolls and squeegees designed to reduce solution losses.
Some plants, primarily hot coating lines with their slower
line speeds, minimize carryover of wastes so effectively
that no treatment of wastewaters is required. Spent
pickling and cleaning solutions are collected separately for
disposal via dumping on wasteland, contract hauling, or deep
wells.
2. The simplest treatment of wastewaters from coating
operations usually begins with blending acidic and alkaline
wastes, then providing space and time for suspended
precipitates to settle out. This blending of wastewaters
causes oily matter to break out of any emulsified forms
present, becoming susceptible to removal via skimming or
through adhering to the settleable solids. To avoid slugs
of extremely acidic or alkaline wastewaters, the
concentrated solutions are collected separately, stored, and
then allowed to combine with rinses in predetermined flow
ratios to provide the best mixing conditions possible in
this relatively crude system.
3. A significant improvement in treatment methods is
attained through controlled neutralization of the combined
wastewaters, using an alkaline material such as lime or
caustic soda to achieve higher pH levels than is possible
through simply blending the wastewaters. Normally, a
polymer is also used to enhance settling characteristics,
and relatively sophisticated clarifiers are installed to
efficiently handle the large volumes of metallic hydroxides
which precipitate out. Sludges are dewatered using vacuum
filtration and go to landfill areas. The effluent waters
are suitable for discharge, sometimes requiring a final pH
adjustment with acid.
391
-------
4. Refinements in treatment techniques would depend on the
sources of wastewaters handled in the treatment system.
These would be tailored to specific needs, for example:
Reduction of Hexavalent Chromium. Coating operations
producing chromate or dichromate wastes normally have
separate pretreatment stages to reduce toxic Cr+6 to Cr+3
prior to neutralization. Most often, the ferrous iron from
pickling rinse solutions or spent pickle liquors is blended
with the chromium wastewaters. In rarer cases, additional
reducing agents such as bisulphites or sulfur dioxide gases
are used in place cf or in addition to pickling wastes. The
reduced chromium-containing wastes are then passed along to
a controlled neutralization treatment stage, where the
addition of lime or caustic soda precipitates all chromium
as the hydroxide. Alternatively, the chromates may be
precipitated out of solutions by the addition of barium
salts, such as sulfates or carbonates. A precipitate of
barium chromate is separated out for subsequent separate
recovery of barium and chromium. Also, ion exchange
techniques can be utilized to recover clean chromic acid
from strong solutions contaminated by iron and trivalent
chromium. The recovered acid is reused in the plating or
chemical treatment operations.
5. Joint treatment systems combining wastewaters from many
different sources into one terminal treatment plant are
becoming increasingly common. In these, wastewaters from
coating operations usually represent a minor portion of the
total flow. Such terminal treatment systems may incorporate
any or all of the individual pretreatment stages mentioned
above.
Plant Vi sits
Visits were made to nine different plant locations to study
the individual operations included under the coating
category. Tables 19 and 20 present the summary of the
plants visited in respect to geographic location, daily
production, plant age, and age of the treatment facility.
Tables 101 and 102 present the plants' raw and waste
effluent loads.
Plant 1-2 - Figure 49. This plant treats coating
wastewaters by dilution and reaction with other mill wastes
in a terminal lagoon, with subsequent discharge to the
receiving stream.
Plant MM-2 - Figure 108. This plant combines all coating
wastewaters with wastes from other sources. Treatment
392
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includes equalization, oil separation, aeration,
sedimentation, lagooning, and recirculation to service water
with intermittent blowdown to river.
Plant NN-2 - Figure 109. This plant utilizes equalization,
mixing, two-stage lime addition, polymer feed, and
clarification for treatment of coating wastewaters.
Clarifier underflows are vacuum filtered, then used as
landfill. Overflows are discharged to the receiving stream.
Plant QO-2 - Figure 110. This plant utilizes mixing and
dilution of rinse waters prior to discharge. Solution
dragout is minimized through strict attention to maintenance
of equipment.
Plant PP-2 - Figure 111. This plant utilizes mixing and
dilution or rinse waters prior to river discharge. Solution
dragout is minimized through strict attention to maintenance
of equipment.
Miscellaneous Runoffs
Plant Vi si ts
Samples were collected at two mills during the course of
sampling for other subcategories. Table 21 present the
summary of the plants visited in respect to geographic
location, daily production, plant age and age of treatment
facility. Table 103 presents the plants' raw and effluent
waste loads. ,,
PICKLING AND CLEANING OPERATIONS
Most alloy and all stainless steels are pickled, i.e.,
cleaned in solutions of acids in order to remove surface
scale. The acids used are primarily sulfuric acid and a
combination of nitric and hydrofluoric acids. Molten salt
baths are also used to remove scale and such salts are
either strong oxidizing or strong reducing agents. Water is
used to rinse the products. Acid pickling operations
produce strong spent liquors and rinsewaters, the latter
having generally the same constituents as the former, but
with lesser quantities of contaminants in much greater
volumes. The principle contaminants are free acids and acid
salts of sulfuric, nitric, and hydrofluoric acids; iron; and
the various metals present in the alloy or stainless steels
being pickled, principally chromium and nickel. The unique
contaminants present in the wastewaters produced from the
molten salt scale processes are hexavalent chromium from the
400
-------
oxidizing baths such as kolene and cyanide from the reducing
scale removal processes such as hydride.
COMBINATION ACID PICKLING OPERATIONS
Current control and treatment technology includes the use of
either contract hauling of concentrated spent liquors for
offsite treatment and/or disposal; or neutralization with
lime and lagooning of the neutralized solutions; or
neutralization with lime and solids separation by vacuum
filtration; or neutralization with lime and clarification in
a flocculator-clarifier; or neutralization with evaporation
to dryness. At the present time there is no commercially
demonstrated technology for the treatment of combination
acid pickling acids, although it is under study.
Combination Acid Pickling (Continuous)
Plant Visits
Visits were made to four plants with operations in this
subcategory. Detailed descriptions of the various waste
water treatment practices are presented on individual
drawings. Table 22 presents a summary of the plants visited
in respect to geographic location and daily production of
the facility. Table 104-1 presents the plants' raw and
effluent waste loads.
*
Plant A - Figure 112. This plant utilizes equalization, lime
neutralization, chromium reduction, clarification, chemical
treatment, sludge thickening, and sludge dewatering via
centrifuging to treat waste waters generated in the
continuous strip pickling process.
Plant D - Figure 113. Acid rinses generated by the
continuous strip pickling process are discharged without
treatment.
Plant 1^ - Figure 114. This plant utilizes lime
neutralization of the spent pickling acids, mixing with the
acid rinses, and sedimentation in a lagoon to treat the
waste water generated by the strip pickling process.
Plant O - Figure 115. This plant utilizes equalization,
sodium hydroxide neutralization, aeration, chemical
treatment, and sludge lagooning to treat process rinse water
generated by the continuous strip pickling operation.
Combination Acid Pickling (Batch Pipe and Tube) -
401
-------
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406
-------
Plant Visit
A visit was made to one plant which had this type of
pickling operation alone.
Table 22 presents a summary of the plants visited in respect
to geographic location and daily production of the facility.
Table 104-2 presents the plants' raw and effluent waste
loads.
Plant U - Figure 116._ This plant utilizes batch-type lime
neutralization of the acid rinses and lime neutralization
followed by evaporation of the spent pickling acids
generated by the pickling process.
Combination Acid Pickling (Other Batch)
Plant Visits
Visits were made to three plants with operation in this
subcategory. Detailed descriptions of the various waste
water treatment practices are presented on individual
drawings. Table 22 presents a summary of the plants visited
in respect to geographic location and daily production of
the facility. Table 104-3 presents the plants' raw and
effluent waste loads.
Plant C - Figure 117. This plant utilizes equalization, lime
neutralization, chemical coagulation, and sedimentation to
treat waste water generated in the bar and plate batch
pickling rinse processes. The spent pickling solutions
(HNO_3-HF and H2SOJJ) are disposed of by contract hauler.
Plant F - Figure 118. This plant utilizes equalization, lime
neutralization, and sedimentation to treat waste water
generation by the plate mill batch pickling rinse process.
The spent waste pickle liquor is removed from the plant to a
company disposal site.
Plant L - Figure 119. This plant utilizes municipal co-
treatment to treat process rinse water generated by the
batch bar pickling operation. Waste pickle liquor solutions
are treated in plant utilizing lime neutralization.
SCALE REMOVAL OPERATIONS
Kolene
Current control and treatment technology consists of
combining and equalizing all of the process water flow from
407
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the kolene scale removal process with that of the effluents
from acid pickling processes and treating the combined flows
in ways similar to those described for combination acid
pickling waste waters, with the addition of provisions for
reduction of hexavalent chromium as necessary.
Plant Visits
A visit was made to three plants which had this type of
scale removal process. Detailed descriptions of the various
waste water treatment practices are presented on individual
drawings. Table 23 presents a summary of the plants visited
in respect to geographic location and daily production of
the facility. Table 105 presents the plants1 raw and
effluent waste loads.
Plant L - Figure 120. This plant utilizes municipal co-
treatment to treat process rinse waters generated by the
kolene descaling process.
Plant C - Figure 121. Once-through waste water from the
kolene quench tank discharges to a receiving stream without
treatment.
Plant Q - Figure 122. Once-through waste water from the
kolene rinse tank discharges to a receiving stream without
treatment,
Hydride
Current control and treatment technology is similar to that
described for the kolene scale removal process waste waters,
with the exception that provision is made for cyanide
oxidation, rather than for chromium reduction. Table 23
presents a summary of the plants visited in respect to
geographic location and daily production of the facility.
Table 105 presents the plants' raw and effluent waste loads.
Plant Visit
A visit was made to one plant which had operations in this
subcategory.
Plant L - Figure 123. This plant utilizes municipal co-
treatment to treat process rinse water generated by the
hydride scale removal operation.
WIRE PICKLING AND COATING OPERATIONS
414
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Wire products are pickled with various acids and are
frequently coated with other metals such as copper, lead,
and/or molybdenum. These coatings are often applied by
deposition from solutions of the metal salts. Water is used
to rinse the products.
Current control and treatment technology consists of the
combination of such wastes and treatment in ways as
described for combination acid pickling waste waters with
prior oxidation of cyanide if necessary.
Plant Visits
Visits were made to three plants which have operations in
this subcategory. Detailed descriptions of the various
waste water treatment practices are presented on individual
drawings. Table 24 presents a summary of the plants visited
in respect to geographic location and daily production of
the facility. Table 106 presents the plants' raw and
effluent waste loads.
Plant K - Figure 124. This plant utilizes equalization, lime
neutralization, chemical coagulation, clarification,
centrifuging, and recycling to treat waste waters generated
by the Bar and Wire Batch Pickling rinse process and the
Copper, Lead, and Molybdate Coating Processes.
Plant L - Figure 125. This plant utilizes municipal co-
treatment to treat process rinse waters generated by the
Wire Mill Cleaning and Coating Operations. Waste pickle
liquor solutions are treated in plant utilizing lime
neutralization.
Plant Q_ - Figure 126. This plant utilizes equalization,
sodium hydroxide neutralization, aeration, chemical
treatment, and sludge lagooning to treat process rinse water
generated by the wire batch pickling operation.
CONTINUOUS ALKALINE CLEANING OPERATIONS
The current control and treatment technology consists of
combining and equalizing the process water flow from the
continuous alkaline cleaning process with that of the
effluents from acid pickling processes and treatment of the
combined flows in ways similar to those described for
combination acid pickling waste waters.
Plant Visit
421
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A visit was made to one plant which incorporated the
continuous alkaline cleaning process. Table 25 presents a
summary of the plants visited in respect to geographic
location and daily production of the facility. Table 107
presents the plants' raw and effluent waste loads.
Plant I - Figure 127. This plant utilizes sedimentation to
treat the waste water generated by the Continuous Alkaline
Cleaning Process.
SPECIFIC PARAMETER REMOVAL OR CONTROL
Acidity and Alkalinity
The purpose of the test, and its common terminology, is to
facilitate the calculation of equivalent amounts of any
substance (acid or base) required to neutralize the acidic
or alkaline components in a water or waste stream.
In general, the acid or alkaline capacity of a waste is not
the primary basis for treatment prior to discharge, except
in some specialized waste situations. In most cases, it is
the toxicity or other detrimental qualities of the substance
contributing to acidity or alkalinity that is the basis for
its removal. An example of this would be in the treatment
of heavy metals (Fe, Ni, Cr, etc.) via precipitation as
hydroxides.
Three methods of treatment applicable for the disposition of
wastes containing high acidity or alkalinity values are as
follows:
Blending with Other Wastewaters. This technique is
applicable only if sufficient dilution or neutralization
capacity is available in the treatment system such that
discharge standards are not exceeded for the acidity,
alkalinity, or any component in the waste.
Direct Neutralization with Acids or Bases. This form of
treatment is utilized when high concentrations or large
volumes of waste are encountered.
Chemical Precipitation. This method is restricted to wastes
capable of generating precipitates with chemical treatment.
A typical example of this technique would be the
precipitation of carbonate alkalinity with calcium.
Chromium
426
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T: i
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(158 tons steel/dav)
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STEEL INDUSTRY STUDY
CONTINUOUS ALKALINE CLEANING
WASTEWATER TREATMENT SYSTEM
WATER FLOW DIAGRAM
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428
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Chromium is used in the steel industry as a basic ingredient
in the manufacture of stainless steel. The percentage of
chromium in the steel determines its resistance to corrosion
from various chemicals and atmospheres. In the manufacture
of stainless steel, the chromium becomes an integral part of
the steel and is not generally found in the wastewater from
the hot melting and rolling operations.
Chromium in the form of chromic acid is also used
extensively in the steel industry in the electroplating of
sheet, strip pipe, and wire to form a protective coating of
chromic oxide on the steel. A 5-30 second hot bath of 0.5-
1.0% chromic acid follows the nornral plating operation to
form a layer of chromic oxide which adds additional
corrosion resistance to the steel and protects the bright
metallic appearance. The length of bath determines the
degree of resistance to corrosion. Following the chromic
acid bath, the steel is rinsed to remove residual acid.
This rinse water becomes polluted with chromic acid and is a
treatment and disposal problem.
Several other processes using chromic acid and chromates in
combination with other compounds are in use by the industry
to prepare the steel for electroplating and/or the
application of organic coatings such as paints and lacquers.
Some of these processes are Chromodizing, Cronak Treatment,
Iridite Treatment, and Anozinc Treatment. Whenever these
processes are used or whenever electrolytic tin, chrome
(tin-free steel), zinc or galvanized processes are used, a
wastewater containing chromic acid will be generated and
must be treated before discharge to the receiving waters.
There are four treatment systems for the recovery or
treatment of chrome-bearing waste currently in use in the
industry. These systems are (1) reduction of the Cr+6 to
Cr+3 and precipitation with lime, (2) recovery by ion
exchange, (3) evaporative recovery systems, and (4) the MST
Process which precipitates the Cr+6 in the hexavalent form
using a proprietary compound. Each of these systems and
combinations thereof, when properly operated, produce a
suitable effluent for discharge to the local receiving
waters.
»
Reduction and Precipitation. The reduction of hexavalent
chromium to the trivalent form and precipitation with lime
is most generally used to treat those waters being
discharged from a plant. In this process, the pH of the
chrome-bearing wastewater is lowered to 2-3 using sulfuric
acid or spent pickle liquor. At this point, a variety of
reducing agents can be used to reduce the Cr+6 to Cr+3.
429
-------
These include anhydrous sodium bisulfite (sodium
metabisulf ite or ABS), sodium sulfite, sulfur dioxide,
ferrous sulfate, and organic materials such as sugar and
methyl alcohol. In the steel industry waste pickle liquor
is generally used, for it normally contains sufficient
ferrous iron to reduce the chrome to the trivalent form. At
a pH of 2 this reaction is practically instantaneous and is
noted by the change in color from yellow to green.
At this point, the chrome is in a soluble trivalent form.
In order to remove the chrome from the solution, the pH is
raised to 8.5-9 using lime, at which point insoluble hydrous
chromic oxide rapidly precipitates, and can be removed in a
settling basin. The treated water is satisfactory for
discharge. Dolomite lime and caustic soda may also be used
to precipitate the chromic oxide; however, when using
caustic soda the chromic oxide tends to go back to solution,
while the dolomite lime produces a lighter weight, less
dense sludge which is more difficult to settle and remove.
The reduction and precipitation of hexavalent chrome is the
most flexible system of those in use. It is readily
adaptable to continuous or batch operations and can handle
dilute or concentrated solutions with little difficulty.
Equipment costs and operating manpower are at a minimum.
However, the ultimate disposal of the chromic sludge
presents a problem.
Whenever chrome recovery systems are in use, chrome-bearing
wastes not suitable for recovery are still generated and
must be disposed of by other methods. These wastes,
resulting from spillage in the plating room, leaking pump
seals, backwash wastes, and general clean-up, are
contaminated with oil and suspended solids which could
poison the recovery system. As a result, chrome reduction
systems are also used in conjunction with recovery systems
to treat those wastewaters not suitable for recovery.
Ion Exchange. Ion exchange resins are used in the steel
industry in several different ways to recover chromate from
plating wastes and rinse waters for reuse and for the
production of demineralized water for use in rinsing
operations. The resins are sensitive to pH and chromate
concentration making pH control necessary and making it
necessary to provide a means to control chromate
concentrations in the waste to be treated. They work best
on dilute solutions (under 500 ppm), and can be used to
recover concentrated plating solutions if properly diluted.
Spent regenerant solutions contain traces of hexavalent
chrome and must be treated before being discharged.
430
-------
Three basic schemes utilizing ion exchange techniques can be
applied to recover hexavalent chromium: (1) using an anion
resin, selectively absorb Cr+* from the wastewater and
discharge the water; (2) using a cation resin, selectively
absorb the metal ions from the water while passing the Cr+6
ion. Concentrate the treated water to recover the chromium;
(3) using two ion exchange units in series, remove metallic
ion in a cation exchanger while passing the Cr+6 ion and
absorb the Cr+6 ion on an anion resin. Demineralized water
is returned to the rinse line for recycle and reuse. The
spent regenerant solution from the anion resin is passed
through a cation resin to recover chromic acid free of
metallic ions and suitable for reuse in the plating
operations.
(1) Certain anion resins have the ability to selectively
absorb hexavalent chrome while allowing the metallic ions to
pass on through. By using sodium chloride and sodium
hydroxide to regenerate the resin, the chromate can be
recovered in a suitable form for reuse in a cooling tower
system. This system recovers 90-9536 of the chrome in the
waste, but a chrome reduction system may still be required
to further treat this waste before discharge. This system
is most applicable to treating cooling tower blowdown for
the recovery and reuse of chrome.
(2) The use of a cation exchange unit followed by an
evaporative recovery system recovers chromic acid suitable
for reuse in plating baths, and provides distilled water for
reuse in the final rinse tank. The key to success of this
process is to treat as small a volume of concentrated waste
as possible. It is essential that waste volumes be
minimized by practicing countercurrent rinsing operations.
The overflow from the concentrated rinse tank is fed to the
cation exchanger and the condensate from the evaporative
recovery system is the fresh (distilled) water makeup to the
rinse system providing complete recycle of the rinse waters.
The concentrated chromic acid in the evaporator is suitable
for reuse in the plating tank. Spent regenerants from the
cation unit must be treated to remove traces of Cr+6.
The cation exchanger removes the metallic ions but not the
Cr+6 from the wastewater prior to the evaporative recovery
unit. These metallic ions would poison the plating solution
or reduce its life if they were returned to the plating
tank. It is essential, therefore, that they be removed from
the waste stream before any effort is made to recover the
chrome.
431
-------
The effluent from the cation exchanger containing Cr+6 is
fed to a continuous evaporator where heat is applied and
water boiled off (evaporated) from the wastewater until a
chromic acid of a concentration suitable for returning to
the plating tank is obtained. This is collected in a
storage tank and returned to the plating bath as required.
The water condensed from the evaporator is a high quality
distilled water and is reused as makeup water to the final
rinse tank.
The use of a cation exchanger and evaporative recovery
system represents complete recycle of the rinse water.
There is, however, in any process, spillage, pump leakage,
and clean-up water that contain oil and suspended matter
that cannot be recycled. In addition, the spent regenerant
of the cation exchanger must be treated. These wastes must
be treated via reduction of Cr+6 to Cr+3 and precipitation
to remove hexavalent chrome before discharging these waters.
In this system, the final volume of water requiring
treatment is considerably smaller than the original waste
stream, and chromic acid is recovered in usable form.
(3) Chromic acid can also be recovered by the exclusive use
of ion exchange. In this system, the chrome-bearing
wastewater first passes through a cation exchanger for the
removal of the metallic ions as described above. Cr+6 is
not removed. It then passes through an anion exchanger
where the Cr+* is removed. The water, now demineralized, is
used as makeup water for the final rinse tank on the plating
line.
The cation exchanger is regenerated using a solution of
sodium chloride and sodium hydroxide. The spent regenerant
must be further treated in a chrome reduction system to
remove the final traces of Cr+6. The anion exchanger is
regenerated with sodium hydroxide and the spent regenerant
is fed to another cation exchanger that converts it to
chromic acid suitable for reuse in the plating tank. This
system prolongs the life of the plating bath, and makes it
possible to recover the chrome in the spent plating
solutions by bleeding the spent solution into the recovery
system at a controlled rate. The regenerant from the second
cation unit must be further treated to remove traces of
Cr+6.
Here again other chrome-bearing wastes not suitable for
recovery by ion exchange, as well as spent cation
regenerating solutions must be treated in a chrome reduction
system to remove the final traces of chromium.
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Evaporative Recovery. Evaporative recovery systems can be
used exclusively for the direct recovery of chromic acid
from concentrated rinse water. Here again, as in ion
exchange systems, countercurrent rinsing systems should be
used to minimize water volumes to be concentrated and to
provide as concentrated a feed as possible to the
evaporator.
The concentrated rinse water is fed into an evaporator,
where heat is applied and the rinse water concentrated by
boiling off water as steam. This continues until the rinse
water concentration is the same as the plating bath, when it
is transferred to a storage tank and used as makeup to the
plating solution. The steam is condensed and is reused as
distilled water makeup to the final rinse tank.
The evaporative recovery systems not only recover chrome for
reuse in the plating bath, they also concentrate the
metallic ions that were in the rinse water, and these are
also returned to thev plating bath. These metallic ions
adversely affect the plating operation and limit the life of
the plating solution, making it necessary to frequently
change the plating bath.
Here again, leaking pumps, spillage, and spent plating
solutions not suitable for recovery must be treated before
discharge and a chrome reduction treatment system is
required.
A commercially available process that uses a proprietary
compound to directly precipitate the chromium in the
hexavalent form is available. This process is suitable for
batch or continuous operation; however, due to the cost of
the proprietary chemical, this system is generally applied
only to low volume waste. Advantages of this system are
that equipment requirements are at a minimum, the sludge
generated settles rapidly, and the volume of sludge
generated is only 10% of the sludge generated using the
reduction process.
The composition of the proprietary compound is unknown;
however, it is known that the complete precipitation of
hexavalent chromium can be accomplished by treating chromium
wastewater with soluble salts of lead or barium nitrate,
chloride or acetate. There exists, however, the possibility
of carryover of these lead and barium salts that could prove
to be more toxic than the Cr+*.
The M&T Process makes no attempt to recover chromium;
however, it could be used in place of the reduction and
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precipitation process for removing chrome from small volumes
of rinse waters and disposing of plating solutions. The
reduction in the amount of equipment required and the low
volume of sludge generated (10SS of the reduction process) by
the MST Process may offset the increased chemical costs
where sludge disposal is a problem.
The chrome recovery and precipitation processes described
here are in use in the steel industry today. The chrome
recovery systems not only reduce the volume of waste treated
and the volume of sludge for disposal, they recover the
costly chrome for reuse and provide a high quality rinse
water. Most mills also have a reduction and precipitation
process to treat those wastes not suitable for recovery.
Spent concentrated plating solutions are disposed of by
bleeding them into the reduction process for ultimate
treatment and removal. Some mills mix spent plating
solutions with spent pickle liquors in storage tanks, where
the ferrous sulfate reduces the Cr+6 to Cr+3 prior to the
disposal of the pickle liquor.
The ultimate goal of all systems is to remove or recover the
chrome while generating a minimum amount of sludge requiring
disposal in landfills. In one case, the Cr+6 is reduced to
Cr+3 and the waste mixed with other mill wastewaters prior
to a terminal treatment plant where the final pH of the
total plant waste is adjusted to pH 7.1. Under these
conditions, the Cr+3 passes through the treatment plant
without complete removal, as a pH of 8.5-9 is required to
quantitatively precipitate the Cr+3. Dilution by other mill
wastewater reduces the Cr+3 concentration to acceptable
levels for discharge.
Copper, Lead, Nickel, Aluminum
Copper, lead, nickel, and aluminum are not major
constituents of wastewaters generated during the manufacture
of basic steel shapes and forms. They can, however, appear
in small concentrations depending upon the process used
during that particular step in the steelmaking operation.
These elements, however, are used in the manufacture of
alloy steels as well as in cladded and specially coated
steel products. Nickel is added to the steel to improve
resistance to corrosion. Copper and aluminum sheets can be
cladded to steel sheets to take advantage of the properties
of copper and aluminum while adding the strength and
rigidity of steel. Copper, aluminum, and lead are also
applied as coatings on steel via hot dip, cold coating, and
electroplating operations. It is in the application of
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these coatings that the wastewaters containing these
elements are most likely to be generated.
The most likely sources of these pollutants are the cleaning
and pickling of the steel prior to rolling, drawing or
applying of coatings, the rinsing or quenching of the steel
after the coatings have been applied, and in the disposal of
spent coating solutions. They can be found in the spent
pickle liquors and in the rinse water following the pickling
and coating operations. The wastewaters are, therefore,
generally acid in nature, and the initial water treatment is
focused on the neutralization of the acid.
The basic criteria for the neutralization of spent pickle
liquors is to neutralize the acid and to precipitate the
dissolved iron. In order to precipitate the iron, hydrated
lime is used to raise the pH of the waste to 8.5-9.0. At
this pH, dissolved iron can be reduced in the wastewater to
less than 1.0 ppm. In addition, other metal hydroxides are
also precipitated, in many cases to levels below 0.5 ppm.
These metal hydroxides include those of copper, lead,
nickel, and aluminum.
Cyanides
Cyanides are oxidized at high pH levels, usually by
chlorine, i.e., alkaline chlorination. The initial reaction
is very fast, producing cyanates. Maintenance of a chlorine
residual at near neutral pH for an hour or more oxidizes the
cyanate to nitrogen and CO2 and essentially zero cyanide
levels can be achieved. Cyanide can also be oxidized
electrolytically, and cyanogen compounds can be treated
biologically.
Ferrous Iron
Ferrous iron is generally present in wastewater generated
while forming steel into usable shapes and sizes. During
hot rolling, mill scale forms on the surface of the steel
and must be periodically removed before further processing
the steel. Hydraulic sprays are used to remove heavy scale;
however, as the steel assumes the final shape and cools,
thinner scale is formed which is more difficult to remove.
As a result, the steel must undergo a "pickling" process,
that is, the scale is removed by immersing the steel in a
bath of acid.
Sulfuric acid is the most common acid used. During
pickling, the scale removed from the steel is dissolved in
the acid in the form of ferrous sulfate. When the ferrous
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sulfate concentration in the pickling acid reaches 18-20%,
the pickling acid is no longer usable and must be discharged
and replaced with new acid. Three methods are used to
dispose of this spent pickle liquor which contains 1-3% acid
as well as 18-20% ferrous sulfate. These are deep well
disposal, neutralization, and crystallization to recover
ferrous sulfate and reusable acid.
Deep well disposal has proven successful in some cases, but
not all mills can utilize this system. Some pickling
operations recover a portion of their acid via
crystallization, but the resulting ferrous sulfate may
create a disposal problem.
Neutralization is currently the most widely used method for
disposing cf not only the concentrated spent pickle liquors,
but also the dilute acid rinse waters resulting from the
pickling operation. Various forms of lime and limestone are
used to neutralize this spent acid. This is usually done in
a rapid mixing tank where the pH of the spent acid is
adjusted to 8.5 with lime. The treated waste is then pumped
to a settling basin or lagoon where the precipitated iron in
the hydroxide form settles out along with the associated
calcium sulfate precipitate. In a properly designed and
operated treatment plant, the dissolved iron in the
discharge from the settling lagoon should be less than 1
ppm. The resultant sludge in the lagoon must eventually be
removed and buried in a landfill.
Solutions of the metals in nitric acid are unique in that
the metals, particularly iron, will be largely or wholly in
the oxidized state, depending upon the free acid
concentration. The principal significance of this is that
air oxidation is generally not needed to produce a ferric
hydroxide sludge after neutralization of stainless (HNO3-HF)
pickle liquor.
Oil and Grease
Oily waste discharges from steel mills can be classified
into four categories:
1. Free oils, which usually are a mixture of gear oil,
bearing oil, hydraulic leakage, some coating oil, and
demulsified rolling oil.
2. Oil-coated solids, which consist of small particles of
metal or oxide coated with an oil film.
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3. Water/oil emulsions in which water is the discontinuous
phase. The emulsions themselves are generally unstable and
are relatively easily broken with heat or simple chemical
treatment, such as pH adjustment.
U. Oil/water emulsions (soluble oils) in which oil is the
discontinuous phase. These materials are stable dispersions
and show no tendency to separate without treatment.
Two basic types of emulsifiers are available for the
formulation of oil/water emulsions and can be utilized
either singly or in conjunction with each other. These are
anionic types that are relatively easily broken with
chemical treatment, and nonionic types which usually require
special emulsion breaking chemicals and techniques.
Treatment processes utilizing these specialized demulsifiers
are usually restricted to batch treatment of concentrated
oil wastes because of the high treatment costs.
Two sources of oil by type (solubles/non-solubles) are
present in steel production: hot rolling and cold rolling.
An average analyses of cold mill waste streams would present
the following compositions:
1. Free oil, water/oil emulsions, and oil coated solids
which are subject to flotation, will contain approximately
50% oil and 8% water.
2. The oil/water emulsion will contain approximately 1-5%
oil and 0.1% solids.
Hot rolling operations would generally contribute only free
oil, water/oil emulsions, and oil coated solids, which are
subject to gravity separation.
These waste stream analyses could only be classified as
typical for the industry as a whole. Numerous plants may
utilize specialized synthetic lubricants such as hot rolling
emulsions, etc., which are not in wide usage and constitute
a specialized treatment problem for a particular plant or
plant area.
In general, it can be seen that the treatment of oily wastes
is a specific problem for each manufacturing area or mill
and will be subject to change with variations in oil
formulations, the state of repair of the equipment, and the
type of product to be produced.
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The removal of oil from a waste stream can be effected by
the following techniques used either singly or in
combination with each other, depending on the nature of the
waste stream:
Gravity Separation. With the exception of filter
techniques, all oil removal processes are based on density
separation. The process is applicable to the removal of
both floatable substances (i.e., free oil and greases, fine
oil coated solids, water/oil emulsions), and heavier-than-
water materials, such as the larger oil coated metal and
oxide particles. The choice of a particular type of
separator would be determined by the type of waste stream
encountered, and could range from the simple API separator
in which only floatable substances are removed to the more
complex dual function scale pits and clarifiers (with or
without chemical treatment) in which both the floatable and
heavier than water phases are removed.
High Rate Filtration. In general, high rate filtration
employing little or no chemical pretreatment is applicable
for the removal of all forms of oil (free oil, grease,
oil/water, and water/oil) and oil coated suspended solids
from a wastewater stream. While the removal efficiency of
these devices will vary with the nature of the waste (type
of oil, suspended solids, etc.), variations in
concentrations within limits will cause little effect.
Filters, because of their limited waste holding capacity,
should always be preceded by a gross waste removal stage,
such as primary and secondary scale pits, API separators,
clarifiers, etc., in which chemical treatment may or may not
be utilized.
The specific method of handling the filter backwash sludges
will again depend on the nature of the waste. Common
treatment methods include chemical or elevated temperature
oil emulsion breaking with gravity separation, filter cake
generation, and admixture with other sludge producing
processes for further disposal.
While conventional high rate filters do an admirable job of
removing oil, they are subject to oil fouling of the filter
media, and hence may have to be routinely cleaned with steam
at the termination of the backwash cycle. A new generation
of filters has been designed using a radial configuration
(nonuniform gradient), synthetic (plastic) media, and an
external regeneration or cleaning cycle. These units
require only one-fourth the filter depth of conventional
high rate filters, and have been shown to be immune to oil
fouling.
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Floeculation. Flocculation, as a process, is suitable for
the removal of emulsified oils (oil/water) and suspended or
dispersed solids and oils from a process water stream. It
is not suitable for the removal of floating oils and must be
utilized in conjunction with a surface oil skimmer either
preceding, integral with or following the flocculation/
clarification step.
The process is based on a combination of charge
neutralization/ agglomeration and the generation of a metal
hydroxide floe on which the oil wastes can be adsorbed.
The flocculating chemicals (iron or alum) and adjunctant
chemicals are added in a specific order depending on the
ultimate use of the system. High rate mixing at the point
of entry followed by a period of slow agitation is required
for both optimum oil adsorption and the complete removal of
floe from the waste stream.
Since the process is based on gravity separation, sufficient
chemicals (metal hydroxides, wetting agents, etc.) must be
added to rapidly and completely sink the oil-containing floe
to the bottom of the clarifier and retain it there until
removal.
These metal hydroxide floes and their combination with oil
produce a very difficult sludge which usually resists
disposition treatment of any kind. For this reason,
flocculation is seldom utilized in process streams
containing heavy concentrations of oil.
Air Flotation. In the air flotation process, separable
wastes are removed from a process stream by the attachment
of microscopic air bubbles to the impurity and allowing the
resultant lighter than water mass to gravity separate under
quiescent conditions. In some cases where the waste will
not accept direct air attachment, chemical floes and/or
chemical aids are added to adsorb the waste and/or modify
its surface charge for proper air attachment.
Two basic types of flotators are available: mechanical and
dissolved air. In the mechanical design, air is
mechanically entrained in the waste stream prior to the
separation chamber usually via high shear mixers. In the
dissolved air flotation system, elevated pressures are
utilized to dissolve excess air in all or a portion of the
waste stream. This dissolved air is then allowed to release
in the form of microscopic bubbles on pressure letdown at
the inlet to the separation chamber.
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The process in general, because of the critical amounts of
air required and the difficulty in its generation, is
limited to relatively low flow rates and steady state
concentration conditions for optimum operation. For this
reason, this process is usually preceded by both
accumulation and equalization facilities.
The advantages in this form of treatment over conventional
clarification are twofold. First, the basic oil containing
sludge being separated has a low inherent density, and is in
itself amenable to gravity separation and surface removal
and, second, the amount of added flocculants required for
oil/water emulsion removal are minimal, hence producing a
low volume sludge that is optimum for oil recovery.
Phosphate
Phosphates are used in the steel industry as pretreatment
for strip steel prior to applying various inorganic and
organic coatings. Rinsing of the sheet following these
treatments generates a phosphate-bearing wastewater
requiring treatment prior to disposal.
Ortho, trisodium, and pyrophosphates as well as other
proprietary compounds containing phosphates are also used as
alkaline cleaners for the removal of oil and dirt from the
steel strip. Phosphoric acid is used in some pickling lines
including electrolytic pickling. These operations prepare
the strip for further treatment. The alkaline cleaner and
pickling acid used will vary depending on the type of
coating to be applied to the strip.
Proprietary phosphate treatment compounds are used to treat
zinc coated strip or plate to provide a better bonding
surface for lacquers and paints. This treatment is
generally followed by a chromate rinse to protect the sheet
against oxidation until it can be coated. Parkerizing and
Bonderizing are processes that utilize phosphates to prepare
surfaces for painting.
Several systems may be used to precipitate and remove
phosphates from wastewaters. Alum at pH of 5.5-5.6 will
precipitate phosphates. Ferrous sulfate, ferric sulfate,
ferric chloride, and pickle liquor will precipitate
phosphates at a pH of 4.5-5.0. Lime will precipitate
phosphates at pH of 9. None of these systems completely
remove the phosphates; however, in combination they can
lower the phosphates concentration in the wastewater to an
acceptable level.
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Wastewater treatment systems in steel mills are not
primarily designed for the removal of phosphates. The
neutralization of pickle liquors with lime and the use of
alum as a flocculating agent to meet effluent standards
already incorporate these methods for phosphate removal so
that no special treatment systems are required to remove
phosphates. In the lime treatment of wastewaters, the
operating pH may be predicated on the ability to obtain good
suspended solids removal rather than on phosphorous removal.
In a properly designed wastewater treatment system where
pickle liquor is neutralized with lime either prior to or
after oil removal the phosphate level should be well within
the effluent standards.
Sulfate
Sulfate as a waste product in the steel industry is
attributable to numerous processes among which the coking
and blast furnace operations of the basic iron industry and
the pickling or cleaning of steel products could be
considered to be prime contributors.
The concentrations and volumes of these sources are varied,
and are dependent en the particular processes utilized.
Treatment processes applicable for the removal or reduction
in concentration of sulfate fall into two types—those that
reduce the total dissolved solids content of the waste
stream such as evaporation and crystallization, and those
that maintain or add to the total dissolved solids such as
dilution, ion exchange, and chemical precipitation.
The method selected for the removal of sulfate is dictated
not only by its concentration, the volume of the waste
stream, and its ultimate use such as disposal or reuse, but
on the other ions contained with it in the waste.
Evaporation, crystallization, and precipitation techniques
are primarily intended for high dissolved solids conditions
such as pickle liquors (ferrous sulfate) , recycled contact
cooling liquors, and scrubbing liquors (ammonium sulfate).
Ion exchange, when usable, is primarily applicable to low
concentration conditions.
In-plant dilution, which often makes use of the plant's
central waste treatment facility, is the most widely used
method of treatment. If during dilution, precipitation does
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occur, it is subsequently removed before being discharged
into the receiving body.
Sulfide
Sulfide wastes in the iron and steel industry are derived
from two principal sources: (1) high temperature gaseous and
solids (slag) production encompassing both the coking and
blast furnace operations in the basic iron industry, and the
fossil fueled cupolas employed in the iron foundry industry,
and (2) low temperature ionic production from the pickling
or cleaning of steel with sulfuric acid. In both cases the
sulfide ion (S=) is derived from sulfur or sulfur containing
compounds via chemical reduction.
The sulfide ion and its associated ionic compounds have the
following chemical characteristics which can be utilized to
both limit its production rate or enhance its removal from a
waste stream.
1. Its decreasing solubility with increasing hydrogen ion
content (low pH) .
2. Its high reactivity as a reductant, especially at low pH
values.
3. Its reactivity with heavy metals to form insoluble
precipitates.
H. Its biological degradability.
The removal of sulfides from a waste stream can be
accomplished either as a separate treatment process or
combined with other waste materials. Some of these
treatment methods are as follows:
Aeration. This process is primarily applicable to wastes
containing high sulfide concentrations. In principal, the
sulfide compound in the waste stream is subjected to
aeration in which both air stripping and in-situ oxidation
of the sulfide occurs. Both the stripping and oxidation
rates are a function of pH with maximum rates being obtained
at low pH values. The high rates of aeration reguired can
be obtained via stripping towers, spray towers, lagoon
aeration, etc.
Chemical Oxidation. Oxidants such as chlorine, ozone, etc.,
are effective with sulfides but may have limited application
in high volume or high concentration situations because of
higher than average treatment costs.
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Biological Oxidation. This form of treatment would be
primarily applicable to the removal of sulfides when they
are combined with other wastes such as phenols, etc., as
found in the coke producing processes.
Piluti on with Other Process Waters. This process is
essentially that of oxidation (biological and chemical) and
is probably the easiest and most effective treatment method
for sulfides in low concentrations. The success of this
treatment is dependent on the presence of sufficient
dissolved oxygen in the other process stream to perform the
required oxidation. The presence of other competing
reducing agents (oxygen consuming substances) such as
ferrous iron should be minimal unless additional aeration is
considered.
Suspended Solids
Suspended solids in the steel industry for the most part
fall into the following categories:
1. Metal Oxides
2. Metal Hydroxides
Iron oxides comprise the major source of suspended solids in
the steel industry. They are indigenous to the blast
furnace production of iron, all steelmaking operations, and
the hot steel rolling operations. The treatment of the
blast furnace suspended solids have been and will most
likely continue to be treated via gravity separation in what
are referred to as thickeners. These devices are large
circular clarifier type structures incorporating continuous
underflow draw-off. The disposition of the underflow sludge
is ultimately back to the blast furnace.
The removal of suspended solids from the hot rolling oper-
ations on the other hand is performed by a diverse group of
methods all of which are based on a sequential treatment
scheme.
The selection of the optimum treatment system is a highly
complex one based on the following criteria:
1. Flow
2. Particle size distribution
3. Suspended solids loading
U. Available space
5. Initial and operating costs
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Wastes from hot rolling operations are highly variable in
composition. Blooms, billets, slats, and plate produce a
large volume of very coarse scale which in most cases is
amendable to treatment utilizing a primary scale pit
followed by clarification with chemical flocculation.
The production of hot rolled strip, sheet, and shapes,
however, produces a wide latitude of particle sizes all of
which are not only unique to the particular rolling mill
configuration but to the types or analysis of the steel
being rolled and the temperature employed in its rolling.
Scale pit removal rates are in turn dependent on detention
time which is influenced both by the waste flow rates and
the pit sludge volume. Filter removal efficiency is in turn
dependent on flow, particle size, and the degree of
exhaustion of the filter.
For this reason, no removal efficiency can be assigned to
any particular stage of the treatment process, but that the
process has to be designed and judged as a whole.
Red iron oxides are indigenous to numerous production
operations such as open hearth furnaces, basic oxygen
furnaces, electric furnaces, scarfing operations, sinter
plants, etc. While this waste was initially considered an
air pollution problem, its transfer to the waste stream via
wet air pollution scrubbers and contact cooling waters has
necessitated its removal in every increasing quantities.
As a waste it is usually treated via gravity separation
techniques. For the most part its treatment has been
confined to thickeners which, when treated with optimum
organic flocculant aids, have provided good separations.
Metal hydroxide in an integrated steel mill can be derived
from two sources: (1) as an added material (flocculant) to
aid in the removal of other soluble or particulate wastes;
or (2) as a soluble metal waste to be removed via
precipitation techniques. In the addition of metal ions for
the control of dissolved and suspended solids, either ferric
sulfate or aluminum sulfate is added to the waste stream and
the pH adjusted to approximately 5-8.
The sorbtive and agglomerative floes generated are utilized
to remove such material as insoluble and soluble oils by
sorbtion, and hard to settle submicron sized suspended
solids by charge neutralization and agglomeration
(flocculation) .
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The separation of this floe and its entrained wastes from
the waste stream can be accomplished by the following common
means:
1. Clarifiers
2. Settling lagoons
3. Air flctators
U. Deep bed filters
The selection of the removal technique will be strongly
influenced by the nature of the influent waste, its
concentration, the amount of flocculant required, the stream
volume, available space, and economics.
Generally, large conditioned floes (rapid settling) are best
handled via Clarifiers and settling lagoons. Suspended
solids that resist optimum floe conditioning (chemically or
economically) are best handled by high rate deep bed
filters. The filter backwash (cleaning) water can in turn
be run into a lagoon or tank for disposition via vacuum
filtration, settling and dredging, coagulation or admixture
with other wastes for disposition.
The processing of gelatinous flocculants containing large
amounts of oil is best done via air flotation. The
disposition of the separated sludge because of its
gelatinous nature can best be accomplished via heat
decomposition, chemical decomposition or admixture with
other diluent solid wastes, etc.
The precipitation of metal hydroxides from plant streams
with calcium hydroxide, sodium hydroxide, etc., has been
applied to a diverse group of metals from the steel pickling
and plating operations. Precipitable metals include Fef Cr,
Cu, Ni, Sn and Zn.
The neutralization of dissolved iron from concentrated
pickle liquor in a mill is relatively uncommon because of
the qross sludge wastes generated and the difficulty of its
disposal. Through proper plant design operation, however,
acid rinse water and some concentration of pickle liquor can
be utilized in the waste and water treatment facilities for
their flocculating capabilities.
The precipitation of chrome, unlike the other waste metals,
is a two-step operation in which the hexavalent chrome ion
is first chemically reduced (usually using ferrous iron from
pickle liquor) to its trivalent state before precipitation
as its hydroxide can occur. Its subsequent precipitation
with hydroxide produces a mixed sludge of ferric and chromic
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hydroxide, which is gravity separated from the waste stream.
Because of the high ratio of hydroxides to other bulk
solids, the waste has a gelatinous characteristic which may
make its separation from the waste stream and dewatering
difficult. Disposition of the sludge is usually via lagoons
for dewatering or admixtured with ether sludges to improve
its dewatering characteristics.
The removal of tin from a waste stream as its hydroxide is a
straight precipitation reaction using any hydroxide source.
In the case of the halogen plating process the use of
calcium hydroxide will result in a mixed precipitation of
tin hydroxide and calcium fluoride (CaF2) . Unlike straight
metal hydroxide sludges, this mixed product settles rapidly
and is easily separable from the waste stream. In many
cases, the waste solids are reprocessed by an outside firm
for reuse.
Zinc
Two processes for the application of a zinc coating to a
steel surface are currently utilized by the steel industry;
hot dipped coatings and electrolytic coatings.
The hot dip process has no apparent zinc wastes of any kind
if good housekeeping procedures are maintained. The only
possible source of zinc from this process would be in the
form of an insoluble metal oxide dross routinely skimmed
from the surface of the molten zinc bath. The other wastes
from this process, consisting of alkaline cleaning
solutions, acid pickling wastes, and oils should not contain
zinc in any form since they precede the zinc coating
operation.
The discharge of zinc from the electrolytic galvanizing
process, however, is a problem. The magnitude and treatment
of which is a function of the type of plating bath utilized
and its inherent dragout rate. Two main types of
electrolytic baths are utilized, acid and alkaline, with
each specific for a particular type of plating operation.
Acid type baths with their high deposition rate and poor
throwing (i.e., ability to plate in corners, etc.)
characteristics are utilized predominately for the
production of steel strip.
Alkaline cyanide baths with their lower deposition rates and
higher throwing capabilities are used predominately for the
production of shapes such as conduit.
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The amount of electrolytes entering a waste system will be a
function of the type of plating operation. Specific figures
for the amount of dragout on electrolyte lost to the waste
system from continuous strip operation are subject to wide
variation. Parameters such as the width of the strip, its
line speed, the method of electrolytic removal from the
strip, the surface tension of the electrolyte, etc., will
all affect the dragout rate. From this it can be seen that
plating waste loadings will be typical only to that
particular operation. The dragout rates encountered with
batch type operations can show wide variations because of
their manual or semi-automatic operation.
The batch dumping of defective or spent electrolyte is
relatively common and can be handled in two ways, a holding
tank having a metered discharge into an existing waste
processing system, or the use of a small batch treatment
plant.
Treatment methods for the removal of zinc from a waste
process stream will depend on the type of electrolyte used.
The treatment of a zinc acid electrolytic waste is a simple
one-step operation calling for the elevation of the waste pH
value to approximately 8.0 with the precipitation of the
zinc as its hydroxide. The range of pH adjustment is
critical as zinc is amphoteric. To all intents, the
discharge of either the acid sulfate or the acid chloride
electrolytic based wastes into an existing buffered waste
stream would result in the precipitation of the hydroxide.
This treatment would be acceptable, providing subsequent
treatment facilities were available for the removal of the
developed suspended solids. The fluoborate electrolyte
should be treated only with lime in a separate plant (batch
or continuous) to effect the precipitations of both the zinc
and toxic fluoride.
Reference level of Treatment
In developing the technology, guidelines, and incremental
costs associated with the application of the technologies
subsequently to be selected and designated as one approach
to the treatment of effluents to achieve the BPCTCA, BATEA,
and NSPS effluent qualities, it was necessary to determine
what reference or minimum level of treatment was already in
existence for practically all plants within the industry in
any given subcategory. The different technology levels were
then formulated in an "add-on" fashion to these reference
levels in so far as possible. The various treatment models
(levels of treatment) and corresponding effluent volumes and
characteristics are listed in Tables 66 through 87.
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It was obvious from the plant visits that many of the plants
in existence today have treatment and control facilities
with capabilities that far exceed the technologies chosen to
be the reference levels of treatment. Even though many
plants may be superior to the base technology, it was
necessary, in order to consider the industry as a whole, to
start at the reference level of technology in the
development of treatment models and incremental costs.
QUANTITY AND QUALITY OF TREATED WATER REQUIRED IN
THE STEEL INDUSTRY
Quantity Requirements
In the previous section it was shown how varied the water
usage is in the steel industry relative to type of treatment
performed. It was shown that it was necessary to classify
water usage by treatment received rather than by industry
subcategory, because of the great number of combinations and
permutations of water use that are practiced.
A similar case presents itself relative to treated water
quantity requirements. As evidenced by the efforts to
establish effluent limits guidelines for the steel industry,
the amount of process water discharged, even among
individual subcategories may vary widely. Water use (and
thus water makeup) may vary from systems that use water on a
once-through basis to systems whose only makeup is to
replenish in-process evaporation.
Thus, because of the variations in types of treated water
used and the quantity used, on a subcategory basis, no
general quantitative estimate of type and amount of treated
water used on a subcategory basis can be provided. Table
108 presents a summary of the water intake according to
industry group.
However, a quantitative estimate of treated water usage by
type of treatment is available on an industry-wide basis
from the 1967 Census of Manufacturers. Subject data is from
the year 1968 and is summarized below:
Quality Requirements
For the purposes of this section, the quality requirements
are based upon the treatment received, since specific raw
water treatment processes generally provide fairly specific
water qualities, depending upon the process.
448
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Coarse Screening. Coarse screening is employed to remove
general debris from the water source at the intake. This
includes twigs, fish, cans, bottles, etc., anything that if
admitted into the plant system would create gross blockages
of pump impellers, cooling loops, piping, etc.
Although definitions of coarse screen size are imprecise,
coarse screens usually have 1/U in. openings or larger.
Strainers or Straining Filters. Strainers are still
basically screening devices, although of finer size. Their
function is still to remove relatively gross sizes of
particulates from the incoming water. Screen size is
generally 1/4 in. or less, with many applications going
into fine mesh sizes.
This equipment is capable of removing grit-sized materials
and other debris which, if introduced into the plant water
system, might cause buildups in areas of poor flow
streamline and cause eventual blockages.
Sedimentation. Plain sedimentation usually involves the
introduction of the water to be treated into a large basin
or tank to reduce the velocity of flow to a point where
sediment and other suspended matter may settle out by the
force of gravity.
For a sedimentation unit to operate properly, the horizontal
velocity must be minimized and the detention time maximized
such that the sediment has sufficient time to settle to the
bottom and not be subjected to scour once it has settled.
Practical limits to the optimization of the above parameters
exist since overall pcnd size is usually limited by other
factors.
In addition, a properly designed sedimentation unit must
have good inflow distribution and outflow collection
principles incorporated into its design to prevent excessive
turbulence and resuspension of materials in these critical
areas.
Generally, a properly designed sedimentation unit can
produce a treated water containing 50-100 mg/1 suspended
matter, depending upon the relative fineness of matter to be
removed.
Clarification. In the steel industry, clarification usually
involves introduction of the raw water into a circular unit
with a bottom shaped like an inverted cone. The water is
introduced near the bottom of the cone and allowed to rise
450
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in an upflow pattern through the unit. The change in cross-
sectional area as the water rises reduces its upflow
velocity to a point where solids tegin to settle. As the
solids settle, they are contacted with other solids in the
upflow water, agglomerate or coalesce, and thus experience
enhanced settling.
The net effect is the formation of a fluid blanket or bed
through which raw water must pass. As the water passes
through the bed, further solids are removed by this bed. In
practice, chemicals may also be added with the wastewater to
help produce this blanket or to enhance the agglomeration
tendencies of the suspended matter in the raw water.
Cold Lime Softening. In the steel industry, cold softening
processes are used to reduce natural hardness in the
incoming water supply. In this process, lime and sometimes
soda ash are added to precipitate various forms of calcium
and magnesium in the raw water which contribute to the total
hardness. Often coagulants such as aluminum sulfate,
ferrous sulfate, ferric sulfate, or sodium aluminate are
also added in conjunction with the softening chemicals to
aid in settling the precipitates formed.
An additional benefit from a cold lime softening operation
is that it can also be used as a clarification operation to
remove suspended matter, since the precipitating hardness
parameters and coagulants would assist suspended solids
removal.
Algicide Addition or Chlorination. In the steel industry,
treated water from sedimentation, clarification or cold
softening operations is sometimes treated with algicides or
chlorine to inhibit the growth of bacterial organisms within
the plant internal piping systems.
In particular, where the water is to receive further
treatment in bed-type units (filters, zeolite softeners, ion
exchangers) the water is periodically shot-chlorinated to
inhibit biological growth and fouling of the bed media.
The net effect of algicide or chlorine addition is to
disinfect the water supply before use or further treatment.
Filtration. If the treated water from sedimentation,
clarification, or cold lime softening units is intended to
go on to ion exchange type treatment units, it is subjected
to an intermediate filtration step, usually after
chlorination.
451
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The filtration step removes finely divided suspended matter
that was not removed by the sedimentation, clarification., or
cold lime softening units as well as after-precipitates that
may form from cold lime softening practices. The primary
function of this filter bed is to prevent the fouling of the
ion exchange resin beds by residual suspended matter.
The filters usually employed have sand and gravel or
anthracite coal, sand, and gravel media.
A properly designed and operated filter system of this type
can produce a treated water containing less than 10 mg/1
suspended matter.
Adsorption. Another treatment unit that is often used prior
to ion exchange is activated carbon adsorption. This unit
is designed to remove any trace organics that might be
present in the water and might foul the resin beds. In
addition this unit removes any residual chlorine in the
water which might oxidize the resin beds.
The effluent from a carbon adsorption unit should be free of
soluble organic matter and free residual chlorine.
Zeolite Softening. Zeolite softening is an ion exchange
process where the ion exchange resin is usually operated on
a sodium cycle basis to remove hardness producing cations
from the water supply. This process is normally used to
produce water for boiler makeup.
A zeolite softener can produce an effluent water containing
zero total hardness.
Demineralization. Demineralization, or complete ion
exchange, is used in the steel industry to produce very high
quality water for high quality product operations, for
example, final rinsing of coated products.
In this process, essentially all the cations and anions are
removed, with some exceptions, from the water to be treated.
In particular, strong acid cation resins are used to remove
essentially all the cations from the water. Weak base anion
resins are used where background silica and carbonate
concentrations permit, to remove all but these trace
cations. Where background silica and carbonate levels are
unacceptably high (some well waters), a strong base resin is
used.
A properly designed and operating cation-anion ion exchange
system will produce a water containing essentially no
452
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cations and no anions (except for silica and carbonate for a
weak base system) in the treated water supply.
453
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