EPA 440/1-73/008
Development Document for Proposed
Effluent Limitations Guidelines and
New Source Performance Standards
for the
SMELTING and SLAG
PROCESSING
Segment of the Ferroalloy
Manufacturing Point Source Category
UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
AUGUST 1973
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DEVELOPMENT DOCUMENT
for
PROPOSED EFFLUENT LIMITATIONS GUIDELINES
and
NEW SOURCE PERFORMANCE STANDARDS
FOR THE SMELTING AND SLAG PROCESSING
SEGMENT OF THE
FERROALLOY MANUFACTURING POINT SOURCE CATEGORY
Russell Train
Administrator
Robert L. Sansom
Assistant Administrator for Air & Water Programs
Allen Cywin
Director, Effluent Guidelines Division
Patricia W. Diercks
Project Officer
September, 1973
Effluent Guidelines Division
Office of Air and Water Programs
U.S. Environmental Protection Agency
Washington, D.C. 20460
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Publication Notleg
This is a development document for proposed effluent limitations
guidelines and new source performance standards. As such, this report
is subject to changes resulting from comments received during the period
of public comments of the proposed regulations. This document in its
final form will be published at the time the regulations tor this
industry are promulgated.
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ABSTRACT
For the purpose of establishing effluent limitations guidelines and
standards of performance for the ferroalloys industry, the industry has
been categorized on the basis of the types of furnaces, air pollution
control equipment installed, and water uses. The categories are as
follows:
I Open Electric Furnaces with Wet Air Pollution Control
Devices
II Covered Electric Furnaces and Other Smelting
Operations with Wet Air Pollution Control Devices
III Slag Processing
IV Non-Contact Cooling Water
The effluent limitations to be achieved by July 1, 1977 are based upon
the pollution reduction attainable using those treatment technologies as
presently practiced by the average of the best plants in these
categories, unless present technology is uniformly inadequate within a
category. The technologies are for the most part based upon the use of
•end of pipe1 treatment and once-through water usage.
The effluent limitations to be achieved by July 1, 1983 are based upon
the pollution reduction attainable using those control and treatment
technologies as presently practiced by the best plant in the category,
or readily transferrable from one industry process to another.
The new source performance standards are based upon the best available
demonstrated control technology, process, operating methods, or other
alternatives which are applicable to new sources.
Costs are given for the various levels of treatment identified tor each
category and for the attainment of the suggested effluent guidelines and
new source performance standards.
111
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CONTENTS
Section Page
I Conclusions 1
II Recommendations 3
III Introduction 7
IV Industry Categorization 45
V Waste Characterization 51
VI Selection of Pollutant Parameters 63
VII Control and Treatment Technology 65
VIII Cost, Energy and Non-Water Quality Aspect 133
IX Best Practicable Control Technology Currently 147
Available, Guidelines and Limitations
X Best Available Technology Economically 153
Achievable, Guidelines and Limitations
XI New Source Performance Standards and 159
Pretreatment Standards
XII Acknowledgements 165
XIII References 167
XIV Glossary 171
Supplement A 175
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FIGURES
Page
1 Ferroalloy Production Flow Diagram 20
2 Submerged-Arc Furnace Diagram 24
3 Cross Section of Open Furnace 25
H Flow Sheet LC Ferrochromium 32
5 Vacuum Furnace for Ferroalloy Production 35
6 Induction Furnace Diagram 36
7 Plant A Water and Wastewater 70
8 Plant B Water and Wastewater 76
9 Plant C Water and Wastewater 81
10 Steam/Hot Water Scrubbing System 88
11 Plant D Water and Wastewater Systems 89
12 Plant E Water and Wastewater Systems 94
13 Plant F Water and Wastewater Systems 105
1U Plant G Water and Wastewater Systems .108
15 Diagram of "Wet Baghouse" System 114
16 Plant H Water and Wastewater Systems .115
17 Diagram of Waste Water Treatment System 121
18 Cost of Treatment Vs. Effluent Reduction 140
Category I
19 Cost of Treatment Vs. Effluent Reduction 141
Category II
20 Cost of Treatment Vs. Effluent Reduction 142
Category III
21 Cost of Treatment Vs. Effluent Reduction 143
Category IV
vi
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TABLES
No^ Page
1 Ferroalloy Facilities and-Plant Locations 13
2 Ferroalloy Production and Shipments in 1970 12
3 No. of Plants versus Values of Shipment - 1967 14
U Water Intake, Use, and Discharge: 1968 15
5 Water Intake by Water Use Region: 1968 15
6 Water Intake, Use, and Discharge: 1968 16
7 Intake, Use, and Discharge by Water Use 17
Region: 1968
8 Intake Water Treatment Prior to Use: 1968 18
9 Water Treated Prior to Discharge: 1968 18
10 Material Balance for 50% Ferrosilicon . 26
11 Ferromanganese Charge Materials-Flux Method 27
12 Ferromanganese Charge Materials - Self-Fluxing 28
Method
13 MC Ferromanganese Charge Materials 29
m Silicomanganese Charge Materials 29
15 Charge Materials for HC Ferrochromium 30
16 Raw Material Components to Smelting Products 31
for HC FeCr
17 Typical Furnace Fume Characteristics 38
18 Production and Emission Data for Ferroalloy 42 .
Furnaces
19 Types of Air Pollution Systems Used on American 43
Ferroalloy Furnaces
20 Illustrative Off-Gas Volumes from Open and Closed Furnaces
41
21 Raw Waste Loads-Open Chromium Alloy and 54
Ferrosilicon Furnaces with Steam/Hot
Water Scrubbers
vii
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22 Raw Waste Load - High Energy Scrubber 55
On Open Electric Furnace
23 Raw Waste Loads-Open Chromium Alloy Furnaces 55
with Electrostatic Precipitators
24 Raw Waste Loads for Covered Furnaces with 56
Disintegrator Scrubbers
25 Raw Waste Loads-Sealed Silicomanganese Furnace 57
with Disintegrator Scrubber
26 Raw Waste Load-Covered Furnaces with Scrubbers 58
27 Raw Waste Loads-Aluminothermic Smelting with 59
Combination Wet Scrubbers and Baghouse
28 Raw Waste Loads-Slag Concentration Process 60
29 Raw Waste Loads-Noncontact Cooling Water— 61
Submerged-Arc Furnaces
30 Raw Waste Loads-Noncontact Cooling Water— 62
Submerged-Arc Furnaces
31 Pollutant Parameters for Industry Categories 63
32 Characteristics of Surveyed Plants 65
33 Analytical Data -SP A- Plant A Lagoon Influent 71
34 Analytical Data -SP B- Plant A Lagoon Effluent 7^
35 Analytical Data -SP C- Plant A Cooling Tower #2 72
36 Analytical Data -SP D- Plant A Cooling Tower #1 72
37 Analytical Data -SP E- Plant A Well Water 73
38 Analytical Data -SP A-. Plant B Intake Water 73
39 Analytical Data -SP.B- Plant B Wet Scrubbers 77
40 Analytical Data -SP C- Plant B Thickener Inlet 77
41 Analytical Data -SP D- Plant B Thickener Overflow 78
42 Analytical Data -SP E- Plant B Cooling Water 78
43 Analytical Data -SP F- Plant B Sewage Plant 79
Effluent
viii
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44 Analytical Data -SP G- Plant B Total Plant 79
Discharge
45 Analytical Data -SP A- Plant C Well Water 82
46 Analytical Data -SP B- Plant C Cooling Tower 82
Slowdown
47 Analytical Data -SP C- Plant C Spray Tower Sump 83
48 Analytical Data -SP D- Plant C Thickener Under- 83
flow
49 Analytical Data -SP E- Plant C Sewage Plant 84
Effluent
50 Analytical Data -SP F- Plant C Sludge Lagoon 84
Effluent
i
51 Analytical Data -SP G- Plant C Thickener Overflow 85
52 Analytical Data -SP A- Plant D Well Water 85
53 Analytical Data -SP B- Plant D Cooling Tower 90
Slowdown
54 Analytical Data -SP C- Plant D Slurry Blend Tank 90
55 Analytical Data -SP E- Plant D Continuous Blow- 91
down
56 Analytical Data -SP D- Plant D Filter Supply 91
Tank
57 Analytical Data -SP F- Plant D Plant Discharge 92
58 Analytical Data -SP A- Plant E Furnace A 95
Scrubber Discharge
59 Analytical Data -SP B- Plant E Furnace B 95
Scrubber Discharge
60 Analytical Data -SP C- Plant E Metals Refining 95
Scrubber Discharge
61 Analytical Data -SP D- Plant E Slag Shotting 96
Wastewater
62 Analytical Data -SP E- Plant E Furnace C 97
Scrubber Discharge
63 Analytical Data -SP F- Plant E Furnace D 97
Scrubber discharge
ix
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64 Analytical Data -SP G- Plant E Furnace E 98
Scrubber Discharge
65 Analytical Data -SP H- Plant E Furnace E 98
Scrubber Settling Basin Discharge
66 Analytical Data -SP I- Plant E Slag 99
Concentrator Wastewater
67 Analytical Data -SP J- Plant E Slag 99
Tailings Pond Discharge
68 Analytical Data -SP K- Plant E Lagoon #3 100
Influent
69 Analytical Data -SP L- Plant E Lagoon #3 100
Effluent
70 Analytical Data -SP M- Plant E Intake River 101
Water
71 Analytical Data -SP N- Plant E Cooling Water 101
Discharge
72 Analytical Data -SP O- Plant E Combined Slag 102
Shotting & Cooling Water Discharge
73 Analytical Data -SP P- Plant E Fly Ash 102
Influent to Lagoon
74 Analytical Data -SP Q- Plant E Fly Ash 103
Influent to Lagoon
75 Analytical Data -SP A- Plant F Intake Water 103
76 Analytical Data -SP B- Plant F Cooling Tower 106
Slowdown
77 Analytical Data -SP C- Plant F Plant Discharge 106
78 Analytical Data -SP A- Plant G Intake City Water 109
79 Analytical Data -SP B- Plant G Cooling Tower 109
Slowdown
80 Analytical Data -SP C- Plant G Spray Tower 110
Discharge
81 Analytical Data -SP D- Plant G Settling Basin 110
Effluent
82 Analytical Data -SP E- Plant G Plant Discharge 111
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83 Analytical Data -SP F- Plant G Slag Processing 111
Discharge
84 Analytical Data -SP A- Plant H Intake City Water 116
85 Analytical Data -SP B- Plant H Baghouse 116
Wastewater Discharge
86 Analytical Data -SP C- Plant H Treated Baghouse 117
Wastewater
87 Analytical Data -SP D- Plant H Settling Lagoon 117
Discharges
98 Analytical Data -SP E- Plant H Polishing Lagoon 118
Discharge
89 Analytical Data -SP F- Plant H Plant Discharge 118
90 Analytical Data -SP G- Plant H Plant Well Water 119
91 Analytical Data -SP H- Plant H Cooling Water 119
92 Control and Treatment Technologies by Category 123
93 Industry Category I, Open Electric Furnace with 128
Wet Air Pollution Control Devices
94 Industry Category II, Covered Electric Furnace and Other 129
Smelting Operations with Wet Air Pollution Control Devices
95 Industry Category III, Slag Processing 130
96 Industry Category IV, Noncontact Cooling Water 131
97 Treatment Level Costs on Unit of Production 136
Basis
98 Treatment Level Costs on Wastewater Flow Basis 137
99 Scrubber Costs vs Fabric Filter Costs 138
100 BPCTCA Effluent Guidelines Treatment Basis 148
101 Best Practicable Control Technology Currently 151
Available Guidelines and Limitations
102 BATEA Effluent Guidelines Treatment Basis 154
103 Best Available Technology Economically 157
Achievable Guidelines and Limitations
104 New Source Performance Standards Basis 160
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105 New Source Performance Standards 163
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SECTION I
CONCLUSIONS
For the purpose of establishing effluent limitations guidelines and
standards of performance for the ferroalloys industry, the industry has
been categorized on the basis of the types of furnaces, air pollution
control equipment installed, and water uses. The categories are as
follows:
I Open Electric Furnaces with Wet Air Pollution control
Devices
II Covered Electric Furnaces and Other Smelting
Operations with Wet Air Pollution Control Devices
III Slag Processing
IV Non-Contact Cooling Water
Other factors, such as age, size of plant, geographic location, product,
and waste control technologies do not justify segmentation of the
industry into any further subcategories for the purpose of establishing
effluent limitations and standards of performance. Similarities in
waste loads and available treatment and control technologies within the
categories further substantiate this. The guidelines for application of
the effluent limitations and standards of performance to specitic plants
take into account the mix of furnace types and water uses possible in a
single plant which directly influence the quantitative pollutional load.
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SECTION II
RECOMMENDATIONS
It is recommended that the effluent limitations guidelines and new
source performance standards be adopted as suggested herein for the
ferroalloy industry. These suggested guidelines and performance
standards have been developed on the basis of an intensive study of the
industry, including plant surveys, and are believed to be reasonable and
attainable from the standpoints of both engineering and economic
feasibility.
The application of these guidelines and performance standards to
specific plants is intended to be on the basis of a "building block"
approach to define the effluent limits from the plant as a whole.
Consider, for example, a large ferroalloy plant having one or more of
the processes and/or water uses in each category. The total effluent
limitation for the plant would be based upon the totals of each
pollutant in each category, determined by multiplying the allowable unit
load by the total production rate in that category. It is recommended
that this method of application of the guidelines and performance
standards be used.
It is recommended that the industry be encouraged to develop or adopt
such pollution reduction methods as the recovery and reuse of collected
airborne particulates for recycle to smelting operations or use in
electrolytic processes, and the use or sale of by-products. The
development or adoption of better wastewater treatment controls and
operating methods should also be encouraged.
The best practicable control technology currently available for existing
point sources is as follows, by category:
I Physical/chemical treatment to remove or destroy
suspended solids and potentially harmful or toxic
pollutants, with recycle of water at the scrubber.
II Physical/chemical treatment to remove or destroy
suspended solids and potentially harmful or toxic pollutants.
Ill Physical/chemical treatment to remove suspended
solids and potentially harmful pollutants.
IV Cooling ponds or alternate treatment to reduce
heat load in the effluent.
The effluent limitations are based on achieving by July 1, 1977 at least
the pollution reduction attainable using these treatment technologies as
presently practiced by the average of the best plants in these
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categories. The above -technologies are based upon the use
pipe1 treatment and once-through water usage.
of •end of
The 30 day average effluent limitations corresponding to the best
practicable control technology currently available are as follows, by
category:
II
kg/
mwhr
Suspended Solids.160
Total Chromium .0032
Hex. Chromium .0002
Cyanide
Manganese .032
Oil .045
Phenol .0032
Phosphate .0064
Heat content
pH 6-9
mwhr
kg/
mwhr
lb/
mwhr
kg/
kkg
352
007
0004
-
070
098
007
0141
.209
.004
.0003
.002
.042
.059
.004
.008
.461 1.330
.009 .026
.0006
.005
.092 .266
.129 .372
.009
.018
III
lb/
ton
2.659
.053
.532
.745
kg/
mwhr
1 .343
.027
.002
376
IV
lb/
mwhr
2.959
.059
.004
,828
6-9
6-9
.161 .355
149,000 592,000
kg cal/ Btu/
mwhr mwhr
6-9
The best available technology economically achievable for existing point
source is as follows, by category:
I Partial recycle of water, with blowdown treated for removal
of suspended solids and potentially harmful or
toxic pollutants by physical/chemical treatment.
II Partial recycle of water, with blowdown treated for removal
of suspended solids and potentially harmful or
toxic pollutants by physical/chemical treatment.
Ill No discharge, attainable by completely recycling all
waters after clarification.
V Partial recycle of cooling water. Blowdown to be adeguately
treated by physical/chemical treatment to
remove potentially harmful pollutants before discnarge
to surface waters.
The effluent limitations are based on achieving by July 1, 1983, at
least the pollution reduction using these control and treatment
technologies as presently practiced by the best plant in each category,
and using transfer of technology where the best plant in the category is
felt to be insufficient.
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The 30 day average effluent limitations corresponding to the best
available technology economically achievable for Categories 1, II and IV
are as follows:
Suspended Solids
Total Chromium
Hex. Chromium
Total Cyanide
Manganese
Oil
Phenol
Phosphate
Heat Content
PH
Category I
kg/mwhr Ib/mwhr
.012 .026
.0004 .0009
.00001 .00002
Category II Category IV
kg/mwhr Ib/mwhr kg/mwhr Ib/mwhr
,0039
,0055
,0002
,0001
.0086
.012
.0003
.0002
016
0005
00001
0003
005
007
0002
0001
.035
.0012
.00002
.0006
.012
.016
.0005
.0002
6-9
6 -
.067
,001
.00003
.019
.004
7,500.
kg-cal/mwhr
9 6 -
.148
.003
.00006
.041
.009
30,000
Btu/mwhr
9
For Category III, the effluent limitation is no discharge o± waterborne
pollutants to navigable waters.
The new source performance standards are based upon the best available
demonstrated control technology, process, operating methods, or other
alternatives which are applicable to new sources. With me exception of
Category I, the best available demonstrated control technology for new
sources is the same as the best available technology economically
achievable, which will be utilized to meet the 1983 limitations. The
standard of performance for Category I is no discharge of waterborne
pollutants to navigable waters. This can be met by installing dry dust
collection devices (i.e., baghouses or fabric filters) on new open
furnaces rather than wet air pollution control devices.
The 30 day average standard of performance for new sources, which
corresponds to the application of best available demonstrated control
technology, process, operating methods or other alternatives for
Categories II and IV are as follows:
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Suspended Solids
Total Chromium
Hexavalent Chromium
Total Cyanide
Manganese
Oil
Phenol
Phosphate
Heat Content
PH
Category II
kg/mwhr Ib/mwhr
0.016
0.0005
0.00001
0.0003
0.005
0.007
0.0002
0.0001
0.035
0.0012
0.00002
0.0006
0.012
0.016
0.0005
0.0002
6-9
Category IV
kg/mwhr Ib/mwhr
,067
,001
,00003
.019
.004
7,500.
kg cal/mwhr
6 -
,148
,003
,00006
.041
.009
30,000
Btu/mwhr
9
For Categories I and III, the standard of performance is no discharge of
waterborne pollutants to navigable streams.
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SECTION III
INTRODUCTION
The Federal Water Pollu-tion Control Act Amendments of 1972 (the "Act")
requires the United States Environmental Protection Agency to establish
effluent limitations which must be achieved by point sources of
discharge into the navigable waters of the United States. Section 301
of the Act requires the achievement by July 1, 1977, of effluent
limitations which require the application of the "best practicable
control technology currently available," and the achievement by July 1,
1983, of effluent limitations which require the application of the "best
available technology economically achievable."
Within one year of enactment, the Administrator is required by Section
30U(b) to promulgate regulations providing guidelines for the effluent
limitations required to be achieved under Section 301 of the Act. These
regulations are to identify in terms of amounts of constituents and
chemical, physical, and biological characteristics of pollutants, the
degree of effluent reduction attainable through the application of the
best practicable control technology currently available and best
available technology economically achievable. The regulations must also
specify factors to be taken into account in identifying the two
statutory technology levels and in determining the control measures and
practices which are to be applicable to point sources within given
industrial categories or classes to which the effluent limitations
apply.
In addition to his responsibilities under Sections 301 and 304 of the
Act, the Administrator is required by Section 306 to promulgate
standards of performance for new sources. These standards are to
reflect 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."
The Office of Air and Water Programs of the Environmental Protection
Agency has been given the responsibility by the Administrator for the
development of effluent limitation guidelines and new source standards
as required by the Act. The Act requires the guidelines and standards
to be developed within very strict deadlines and for a broad range of
industries. Effluent limitations guidelines under Section 301 and 304
of the Act and standards of performance for new sources under Section
306 of the Act will be developed for 27 industrial categories.
Moreover, each of these industrial categories probably will require
further subcategorization in order to provide standards that are
meaningful.
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In order to promulgate the required guidelines and standards, it is
first necessary to (a) categorize each industry; (b) characterize the
waste resulting from discharges within industrial categories and
subcategories; and (c) identify the range of control and treatment
technology within each industrial category and subcategory. Such
technology will then be evaluated in order to determine what constitutes
the "best practicable control technology currently available," what is
the "best available technology economically achievable" and, for new
sources, what is the "best available demonstrated control technology."
In identifying the technologies to be applied under Section 301, Section
304 (b) of the Act requires that the cost of application of such
technologies be considered, as well as the non-water quality
environmental impact (including energy requirements) resulting from the
application of such technologies. It is imperative that the effluent
limitations and standards to be promulgated by the Administrator be
supported by adequate, verifiable data and that there be a sound
rationale for the judgments made. Such data must be readily
identifiable and available and such rationale must be clearly set forth
in the documentation supporting the regulations.
FERROALLOY MANUFACTURE
Ferroalloys are used for deoxidation, alloying,and graphitization of
steel and cast iron. In the nonferrous metal industry, silicon is used
primarily as an alloying agent for copper, aluminum, magnesium, and
nickel. Seventy five percent ferrosilicon is used as a reducing agent
in the production of magnesium by the Pidgeon process. Manganese is the
most widely used element in ferroalloys, followed by silicon and
chromium. Others include molybdenum, tungsten, titanium, zirconium,
vanadium, boron, and colximbium.
There are four major methods used to produce ferroalloy and high purity
metallic additives for steelmaking. These are (1) blast furnace, (2)
electric smelting furnace, (3) alumino- or silicothermic process and (U)
electrolytic deposition. The choice of process is dependent upon the
alloy produced and the availability of furnaces. Ferromanganesfc is the
principal metallurgical form of manganese. This product contains 75% or
more of manganese, the balance being mainly iron. It is produced in the
blast furnace or electric-arc furnace and is available in several
grades. A few steel companies produce ferromanganese for their own use
since they have their own ore sources and suitable blast furnaces
available. The production of ferromanganese in blast furnaces is a part
of S.I.C. 3312 and such production is not considered herein, but will be
covered under the guidelines for the iron and carbon steel industry.
Electric smelting furnaces produce most of the ferroalloy tonnage.
The majority of electric ferroalloy furnaces are termed submerged arc,
although the mode of energy release in many cases is resistive heating.
Raw ore, coke, and limestone or dolomite mixed in proper proportions
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constitute the charge for the electric-arc furnace process. A large
supply of electric power is necessary for economical operation.
Important operating considerations include power and electrode
requirements, size and type of furnace, amount and size o± coke, and
slag losses. The major ferroalloys thus produced are:
1. Silicon Alloys - Ferrosilicon (50-98% Si) and Calcium
Silicide
2. Chromium Alloys - High carbon Ferrochromium in various
grades and Ferrochromesilicon.
3. Manganese Alloys - Standard Ferromanganese and
Sili comanganese
There are a smaller number of furnaces which do not operate with deep
submergence of the electrodes and produce a batch melt which is usually
removed by tilting the furnace. Mix additions and power input would
usually be cyclic. Examples of products produced in this type of
furnace are:
1. Manganese Ore-Lime melt for subsequent ladle
reactions with silicomanganese to produce medium
carbon and low carbon ferromanganese.
2. Chrome Ore-Lime melt for subsequent ladle reaction
with ferrochromesilicon to produce low carbon ferrochromium.
3. Special Alloys, such as Aluminum - Vanadium, Ferrocolumbium,
Ferroboron, Ferrovanadium and Ferromolybdenum.
The largest source of waterborne pollutants other than thermal in the
industry is the use of wet methods for air pollution control; consider-
ation of air pollution sources is thus of importance here. The
production of ferroalloys has many dust or fume producing steps.
Particulates are emitted from raw materials handling, mix delivery,
crushing, grinding, and sizing, and furnace operations. Emissions from
furnaces vary widely in type and quality, depending upon the particular
ferroalloy being produced and the type of furnace used.
The conventional submerged-arc furnace utilizes carbon reduction of
metallic oxides and continuously produces large quantities of carbon
monoxide. Other sources of gas are moisture in the charge materials,
reducing agent volatile matter, thermal decomposition products of the
raw ore, and intermediate products of reaction. The carbon monoxide
content of the furnace off-gas varies from 50-90% by volume, depending
upon the alloy being produced and the amount of turnace feed
pretreatment. The gases rising out the top of the furnace carry fume or
fume precursors and also entrain the finer size constituents of the mix
or charge. Submerged-arc furnaces operate in steady-state and gas
-------
generation is continuous. In an open furnace, all the CO burns with
induced air at the top of the charge, resulting in a large volume of
gas. In a covered or closed furnace most or all of the CO is withdrawn
from the furnace without combustion with air. The controls used are
thus affected by the type of furnace, the gas volume and emitted
particle size and particle characteristics.
Fume emission also occurs at furnace tap holes. Because most furnaces
are tapped intermittently, tap hole fumes occur only about 10 to 20% of
the furnace operating time. Melting operations may be conducted in an
open arc furnace (as opposed to a submerged arc furnace) in some plants.
While no major quantities of gas are generated in this operation,
thermally induced air flow may result in fume emission.
WATER POLLUTION SOURCES
Air pollution control devices include baghouses, wet scrubbers, and
electrostatic precipitators. Wet scrubbers, of course, produce slurries
containing most of the particulates in the off-gases. Spray towers used
to cool and condition the gases before precipitators produce slurries
containing some percentage of the particulates in the gases. Baghouses
generally produce no wastewater effluents. In one plant, however, the
gases from exothermic processes are cooled by water sprays, scrubbed in
wet dynamic scrubbers, and finally cleaned in a baghouse in which the
bags are periodically washed with water.
The only currently feasible type of wet collector for cleaning the large
gas volume from open furnaces is the venturi type scrubber. With
required pressure drops on the order of 152.4 cm (60 in.) W.G. , the
power consumption approaches 10% of the furnace rating. Most venturi
designs allow recirculation of scrubbing liquor so that water
consumption is reduced to that evaporated into the gas plus that exiting
with the concentrated solids stream. The venturi has the advantage of
being able to absorb gas temperature peaks by evaporating more water.
For a ferrosilicon or ferrochromesilicon operation substantially all of
the sulfur in the reducing agent appears in the gas phase, and a
corrosion problem occurs in any liquid recycle system unless neutral"
izing agents or special materials of construction are used.
Electrostatic precipitators have been installed on open furnaces
producing ferrosilicon, ferrochromesilicon, high-carbon ferrochromium,
and silicomanganese, both in this country and abroad. Most ferroalloy
fumes at temperatures below 259.7°C (500°F) have too high an electrical
resistivity, i.e., greater than 1 X 1010 ohm-cm for the use of
electrostatic precipitators. The resistivity is in an accepted range
only if the gas temperature is maintained above 259.7-315=2°C (500-
600°F). Water conditioning would lower the resistivity, but a large
spray tower is required for proper humidification. Stainless steel
construction would be a necessity for ferrosilicon or ferrochromesilicon
10
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operations. The alternate use of steam is feasible if low-cost steam is
available.
The resistivity problem could be overcome by using a wet precipitator,
but water usage appears to be greater than that for a wet scrubber
without recycle. Wet electrostatic precipitators have been used at one
installation in Europe. However, all parts of the precipitator exposed
to the dirty water and to the wet gas were constructed of stainless
steel. Electrostatic precipitators have found limited usage in American
ferroalloy plants, although commonly used in Japan.
1
Submerged arc furnaces may be characterized as open, semi-closed, and
sealed. The latter two types may also be termed covered furnaces. The
open furnace has no cover and air is freely available to burn the CO
coming off from the charge. The semi-closed furnace has a cover through
which the electrodes extend down into the charge; the space around the
electrodes is kept filled with the charge materials to form a quasi-seal
which reduces the emissions from these locations but does not completely
prevent the escape of the gases generated. The sealed furnace has a
similar cover but with mechanical seals around both the electrodes,
which do prevent the escape of gases.
The sealed furnace has thus far been applied only to calcium carbide,
pig iron, standard ferromanganese and silicomanganese. In Japan, it has
also been used to produce ferrochromium, ferrochromesilicon, and 50% and
75% ferrosilicon. Sealed covers are difficult to adapt ro an existing
furnace because of the extensive revisions that are usually required.
The disintegrator types of scrubber was formerly often employed for the
cleaning of gases from covered furnaces. Althougn it can do a good
cleaning job when properly maintained on furnaces producing calcium
carbide, venturi scrubbers do a better job of dust removal tor other
products. The disintegrator type of scrubber has the advantage of
producing a slight pressure head (about 5 cm (2 in.) W.G.), but the
capacity limitations and high water and power consumption make it
uneconomical for most new furnace installations. Additionally, the need
for greater dust removal from furnace gases have caused disintegrator
scrubbers to be eclipsed by venturi scrubbers.
The venturi type scrubber has been installed for cleaning CO gas from
covered furnaces, but the required pressure drops are high (about 152 cm
(60 in.)W.G.). The electrostatic precipitator is a possible CO gas
cleaning device, but has found no such applications in the United
States, although it is commonly used in Japan. It is possible to use a
bag collector to clean CO gas, but only one such installation is known
in the world, and none in this country. A "candle filter" system for
cleaning CO gase$ in ceramic filters, is another (albeit rare) type of
dry dust collectors.
11
-------
Other sources of wastewater in the industry are from cooling uses,
boiler feed, air conditioning, and sanitary uses. Wastewaters also
result from slag processing operations in which slag is crushed and
sized for recovery of metal values, or from slag shotting operations in
which the slag is granulated for further use.
PLANT LOCATIONS AND INDUSTRY STATISTICS
There are some 40 plants in the United States which produce ferroalloys,
chromium, manganese, and other additive metals as tabulated in Table 1.
The 1967 _Census of Manufactures reports 34 establishments in S.I.C.
3313, i.e., primarily engaged in the production of electrometallurgical
products. Of these establishments, only 20 were included in the ±968
Water Use^in Manufacturing data as having used 75.7 million lirers (20
million gals.) or more of water annually. The total value of shipments
in S.I.C. 3313 (34 plants) in 1967 was $467.9 million. The value of
shipments from the 20 large water-using plants was $411.4 million.
Although according to the Minerals Yearbook, 1^10• shipments rather than
production are the measure of activity in the industry, as production in
the high-volume ferroalloys may be irregular and intermittent, for air
and water pollution regulatory purposes production is a better indicator
of industry activity than is shipments. Production and shipments in
1970 were as shown in Table 2.
Table 2. FERROALLOY PRODUCTION AND SHIPMENTS IN 1970
Production
Product
Ferromanganese
Silicomanganese
Ferrosilicon
Silvery Iron
Chromium Alloys:
Ferrochromium
Other
Ferrotitanium
Ferrocolumbium
Total
islsa
757,920
175,285
643,455
178,143
280,876
87,238
3,048
yTl27,~1K)8
tons
835,463
193,219
709,287
196,369
kkg
732,283
156,900
597,909
188,351
309,613 262,481
96,163 73,968
3,360 2,985
1,260 1^289
2,344,734 2,016,166
.Ship_me_njts
Value
tons
807,368
172,988
659,216
207,664
289,395
81,552
3,291
2,222^895
134,456
32,024
136,238
16,853
100,667
25,606
3,503
9,385
458,732"
12
-------
Table 1. TYPES, SIZES, AND LOCATIONS OF FERROALLOY PRODUCING PLANTS IN THE UNITED STATES
U)
Plant
Producers Size Locations
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
Air Reduction Co., Inc.
Airco Alloys Div.
American Potash Co.
Chromium Mining & Smelting
Co.
Climax Molybdenum Co.
Foote Mineral Co.
Hanna Nickel Smelting Co.
Interlake, Inc.
Kawucki Derylco Industries
Kawecki Chemical Co.
Luckenby
Manganese Chemicals Co.,
Diamond Shamrock
Molybdenum Corp. of America
National Lead Co.
New Jersey Zinc Co.
Ohio Ferro Alloy Corp.
Reynolds Metals Co.
Reading Alloys
Sandgate Corp.
Shieldalloy Corp.
Tennessee Alloys Corp.
Tennessee Metallurgical Co.
Union Carbide Corp.
Woodward Co.
Div. Mead Corp.
L
M
M
S
S
M
S
S
L
L
S
M
M
S
L
S
S
S
S
S
S
S
M
L
M
S
S
S
S
S
S
S
L
L
L
S
S
M
M
S
Calvert City, Ky.
Charleston, S.C.
Niagara Falls, N.Y.
Theodore, Ala.
Aberdeen, Miss.
Woodstock, Tenn
Langeloth, Pa.
Cambridge, Ohio
Graham, W. Va.
Keokuk, Iowa
Knoxville, Tenn.
Steubenville , • Ohio
Wenatchee, Wash.
Riddle, Oreg.
Beverly, Ohio.
Springfield, Oreg.
Easton, Pa.
Selma, Ala.
Kingwood, K. Va.
Washington, Pa.
Niagara Falls, N.Y.
Palmerton, Pa.
Brilliant, Ohio
Philo, Ohio
Powhatan, Ohio
Tacoma, Wash.
Lister Hill, Ala.
Robesonia, Pa.
Houston, Texas
Newfield, N.J.
Bridgeport, Ala.
Kimball, Tenn.
Alloy, W. Va.
Ashtabula, Ohio
Marietta, Ohio
Niagara Falls, N.Y.
Portland, Oreg.
Sheffield, Ala.
Rockwood, Tenn.
Woodward, Ala.
Products
FeCr, FeMn, FeSi, FeCrSi
Mn
FeMn,SiMn,FeSi,FeCr,
FeCrSi
FeMo
FeB , FeCb , FeTi , FeV , other
No.
Type of furnace Furnaces
Electric
Electric
Electric
Electric
Electrolytic
Electric
Aluminothermic
Electric
FeCr, FeCrSi, FeMn, FeSi, SiMn Electric
FeSi, Silvery Iron
Mn
FeCr, FeCrSi
FeSi
FeSi
FeCr, FeSi, SiMn
Si
FeCb
FeSi
FeMn
FeMo
FeCbTi, FeTi, other
Spiegeleisen
FeCr, FeSi, Si, FeCrSi
FeB, FeMn, FeSi, SiMn, Si
FeSi, Si
FeCr, FeSi
Si
FeB , FeCb , FeV , NiCb , FeMo
FeMn, SiMn
FeV, FeTi, FeB, FeMo,
FeCb, FeCbTa
FeSi
FeSi
FeB, FeCr, FeCrSi, FeCb ,
FeSi, FeMn
FeTi, Few, FeV, SiMn, other
FeMn, SiMn
FeSi
Electric
Electrolytic
Electric
Electric
Electric
Electric
Electric
Aluminothermic
Electric
Fused Salt Electro-
lytic
Electric & Alumino-
thermic
Electric
Electric
Electric
Electric
Electric
Electric
Electric
Aluminothermic
Electric
Aluminothermic
Electric
Electric
Electric
Electric
Electric,
electrolytic, vacuum
Electric,
aluminothermic
Electric
Electric
Electric
Electric
11
2
1
1
5
3
9
8
6
4
4
7
2
1
3
1
4
10
4
2
1
3
3
2
16
8
11
2
2
5
7
1
Plant size classification
S-Up to 25,000 KW
M- 25,000 to 75,000 KW
L-Over 75,000 KW
-------
In 1970, 345,567 kkgs (381,000 tons) of ferroalloys were produced in
blast furnaces according to the Annual Statistical Report, A.I.S^I^-
122.0=. Plants using other than blast furnaces tnus produced about
1,781,107 kkgs (1,963,734 tons) in that year.
On the basis of the census data and the number of plants enumerated in
Table 1, the distribution of. numbers of plants versus capacity in the
industry appears to be as in Table 3.
Table 3.; NUMBER OF PLANTS VS. VALUES OF SHIPMENTS-1967
Value of Shipments^l million),
No. of plants Ferroalloys Total
20 - 411.4
34 398.2 467.9
40 420.4
The large water-using plants thus account for some 88 pcicenr of the
value of shipments in S.I.C. 3313, while numbering 20 our of 40 and
apparently account for over 80 percent of the total value of the
shipment of ferroalloys.
The 1968 Water Use in Manufacturing data for those estabiishrnenrs using
more than 75.7 million liters (20 million gal) of wattr annually are
summarized in Tables 4 thru 9.
14
-------
Table 4. WATER INTAKE, USE, AND DISCHAPGE: 1968
No. of Establishments 20.
No. of Employees 8,700.
Value Added by Manufacture $168.9 X 106
No. of Establishments Recirculating Water 17
__ Gallons
Total Intake 1128.7 X 10* 298.2 X 109
Intake Treated Prior to Use 3406.5 X 1 O6 900. X 106
Total Water Discharged 1120.7 X 109 296.1 X 109
Intake for Process 4.9 X 109 1. 3 A 10«
Intake for Air Conditioning 757. X 109 200. x 109
Intake for Steam Electric Power 701.4 X 109 185.3 X 10*
Intake for Other Cooling or Condensing 381.5 X 1 O9 100. t) X 109
Intake for Boiler Feed, Sanitary , etc. 40.1 / 1 O9 10. b X 109
Table 5. WATER INTAKE BY WATER USE REGION: 1968
Intake
_^ B§_3i2!l J02_liters 109_gals-. Np^Esrablishmeiits
Delaware and Hudson (D) (D) (D)
Eastern Great Lakes 381.5 100.8 5
Ohio River 684.3 180.8 7
Tennessee (D) (D) (D)
Southeast (D) (D) (D)
Upper Mississippi (D) (D) (D)
Pacific Northwest (D) (D) (D)
(D) Withheld to avoid disclosing data on individual plants.
15
-------
Tal ' 5 6. WATER INTAKE, USE, AND DISCHARGE: 1968
Value of Shipments
Liters
X 10*
Gallons
Intake from Public Systems
Co. Surface Intake
Co. Ground Intake
Gross Water Used
Public Sewer Discharge
Surface Water Discharge
Ground Water Discharge
Transferred to other Users
Treated before Discharge
3028.
1119.
6.
1212.
1514.
1102.
1892.
15.
199.
2
,4
3
2
5
c
,4
X
X
X
X
X
X
X
X
X
1
1
1
1
1
1
1
1
1
06
09
O9
09
06
09
06
09
09
800.
295.
1.
320.
400.
291.
500.
4.
52.
7
7
3
2
1
7
X
X
X
X
X
X
X
X
X
1
1
1
1
1
1
1
1
1
06
09
09
09
06
O9
06
09
09
16
-------
Table 7. INTAKE, USE, AND DISCHARGE BY WATEF USE REGION:
Value of Shipments
$ 97.2
106
Eastern
Liters
Great. Lakes
Gallons
Intake from Public Systems
Co. Surface Intake
Co. Ground Intake
Gross Water Used
Public Sewer Discharge
Surface Water Discharge
Ground Water Discharge
Transferred to other Users
Treated before Discharge
Value of Shipments
Intake from Public Systems
Co. Surface Intake
Co. Ground Intake
Gross Water Used
Public Sewer Discharge
Surface Water Discharge
Ground Water Discharge
Transferred to other Users
Treated before Discharge
1892.
379.
379.
1514.
364.
378.
15.
L
378.
677.
6.
718.
679.
757.
157.
5
6
6
5
5
5
i
c
9
1
8
a
l
X
X
(7.)
X
X
X
X
X
(?)
ter
X
X
X
X
(Z)
X
X
-
X
1
1
1
1
1
1
1
s
1
1
1
1
1
1
1
09
09
09
06
09
06
09
$179
Ohio
06
09
09
09
09
06
09
500
100
100
400
96
100
4
.8 X
Five
100
179
1
189
179
200
41
•
•
•
•
•
.
1
r
G
•
.
•
•
•
•
•
3
3
3
1
0
a
1
6
9
5
5
X
X
(Z)
X
X
X
X
X
(Z)
6
lie
X
X
X
X
(Z)
X
X
-
X
1
1
1
1
1
1
1
>n
1
1
1
1
1
1
1
09
09
09
06
0-9
06
09
s
0*
09
09
09
09
06
09
(Z) Less than 1.89 million I/year (500,000 gal/year)
17
-------
Table 8. INTAKE WATER TREATMENT PRIOR TO USE: 1968
TreatmentEstablishments lQl_!iters IQf
Aeration 1 -
Coagulation 4 1.9 0.5
Filtration 4 1.5 0.4
Softening 4 .4 0.1
Corrosion Control 4 1.5 0.5
pH 3
Other 2 -
None 13
Table 9. WATER TREATED PRIOR TO DISCHARGE: 1968
Treatment Establishments 109 liters 109
Primary Settling 3 -
Secondary Settling 3
Trickling Filters 1 -
Activated Sludge 2 -
Digestion 5 .4 0.1
Ponds or Lagoons 6 157.5 41.6
pH 3 -
Chlorination 3 - -
Flotation 3 . -
Other 9
18
-------
PRODUCTION PROCESSES
The ferroalloy manufacturing processes are listed below witn the product
groups manufactured by each process.
Submerged-arc furnace process -
Exothermic process -
Electrolytic process -
Vacuum furnace process -
Induction furnace process
Silvery iron
50?' Ferrosiliccn
65-75°'. Fc..:rrosilicoii
Silicon m--t.al
Si 1 icon-ir;angan e sr- - zircom urn
"Hich-carbcn (HC) Ferro-
manganese
Silicomanganese
F€.-r romanqanese silicon
Charge chrome
KC ferrccl.romium
Ferrocnrcme silicon
Calcium carbide
Low-car bo:. (LC) terro-
cKroniium
1C ferromanoar.ese
IvcvGium-carbon (MC) ±~-rro-
incrigar.r. se
Chroii'iurr; metal
Titanium, Vanadium and
c:olumbium Alloys
Chromium metal
Manganese metal
LC ftrrochromium
Magnesium ferrosilicon
Ferrotitanium
Ferroalloy production in submerged-arc furnaces consists of raw
materials preparation and handling, smelting, and product sizing and
handling as shown in Figure 1.
RAW MATERIALS PREPARATION AND HANDLING
The mineralogy of individual ores used by the ferroalloys industry is
highly technical and specialized. The ores must be analyzed and
carefully evaluated to identify any undesirable elements. Careful
evaluation of the ore is essential not only with regard to costs,
including government tariffs, since ores are commonly sold on the basis
of contained metal or metallic oxide, but also with regard to freight
charges to ferroalloy plants. Other considerations in the purcnase of
ores are their physical characteristics, ease of reduction, and
analytical specifications necessary to meet customer requirements.
19
-------
Figure t
FERROALLOY PRODUCTION FUDW DIAGRAM
ro
o
FUMES
CRUSHING
SCREENING
STORAGE
SHIPMENT
-------
The United States is dependent almost" entirely upon commercial sources
of manganese and chromium ores from outside the country. inese ores are
imported mainly from South America, Africa, Turkey, India, arid Russia.
Since the time interval between mining the crts and their receipt at the
ferroalloy plants is usually many months, or even as long as a year, a
substantial stock of manganese and chromium ores of the particular types
and grades necessary to produce the desired alloys must be maintained.
It is the general practice to procure ores from familiar sources since
their peculiarities will be Known. Such ores will nave already
demonstrated their suitability for the intended smelting process. There
are not many known chromium ore deposits end their fundamental chemical
composition and physical properties have betr. reasonci£/iy well defined.
The same is true of commercially mined manganese ores.
Most ores come to the market for sale in the dressed state ana are sold
on the basis of their content of the n.etal oxide or metai, i.e.,
contained manganese, chromium oxide, 'etc. In general, ores containing
high percentages of metal oxides are ec.si-.-r to process ana result, in
lower production costs than ores wi~h lew-r percentages or metal oxides.
In addition to chromium and mar.qanes-: ores, columbiuiT.-^eariiiy ores or
slags, titanium ores, and zirconium cr<=s are also importt=a. Commercial
sources of vanaaium and tungsten tearing cree; exist in the United
States. High-purity quartzes or quartzites with low alumina and low
iron oxide are found in selected areas of this country. riiyn quality
limestone deposits are also available domestically at a few locations.
The chromium ores imported and used for ferroalloy prouuction in the
United States have a Cr2o3^ content of about 45 to 53 percent. The
manganese content of the manganese ores ranges from 43 to 54 percent.
Since the ores used for ferroalloy production contain consiaerable
gangue, ore receipts and storage at the ferroalloy plants involve large
tonnages.
The sizing of ores is important. Fine, ores, sucn as flotation
concentrates, are not desirable as a direct charge into reduction
furnaces because such ores lack porosity and do not allow tne release of
reaction gases. Dust losses are therefore high. Fine ores can be used
effectively with minimum mechanical losses in melt furnaces and can
later be reduced with silicon alloys. While work has been done on
briquetting fine ores, equipment investment and briquetting costs have
been difficult to justify through increased production and improved
recovery. On the other hand, ores received at the plants are frequently
oversized and must be crushed to a suitable size.
It is desirable to have in storage an adequate quantity or ore with the
desired chemical analysis and physical properties. i'he desirable
quantities stored will depend on the furnace capacity, marketing
situation, and storage capacity of the plant. The interest on the funds
21
-------
invested in the ores held in storage ir-ay become a significant cost
factor. Often it is possible to assemble ore from several sources which
will complement each other in their composition.
The ore shipment, plus the required quartzes cr quartzites, lime, scrap
steel turnings, and reducing agents, etc., are generally transported to
plants by railway or river barges. Ores are unloaded by traveling
cranes or railroad-car dumpers and moved with belt conveyors to storage
areas. The free moisture in the raw materials is significant, ranging
from 10 to 20 percent. In some plants, the moisture is decreased by
passing the material through driers before use in furnaces.
Care is required in the preparation of furna'ce charges in order to
produce a specified ferroalloy. Normally, raw materials are conveyed to
a mix house where they are weighed and blended. After tne batch has
been assempled, it is moved by conveyors, buckets, sxip noist, or cars
to the hoppers above the furnace, where it may flow by gravity through
chutes to the furnaces.
SUBMERGED-ARC FURNACES
The general design of electric submerged-arc furnaces for tne production
of alloys is basically the same throughout the industry; out tney differ
in electrical connections, arrangements of electrodes, and snape and
size of the hearth. The three carton ele^ctrode-s are arranged in a delta
formation, with the tips submerged .9-1.5 m (3-5 ft.) into tne charge
within the furnace crucible, so the reduction center lies in the middle
of the charge and the reaction gases, formed in the reduction center,
pass upward through the charge. A portion of the heat is transttrred to
the charge and partly prereduces the ore as it. passes downward into the
center of the furnace. Because of the passage of tne reaction gas
through the charge, fume losses are reduced.
Existing submerged-arc furnaces are generally built with an open top,
and large quantities of reaction gases evolved in tue reaction zone
during the reduction process will flow without hindrance into a hood
built above the furnace. The gases burn on the surface of tne charge
supported by the oxygen of in-rushing air, and are then discharged
through stack(s) (after gas cleaning) to the atmosphere. Due to the
open configuration, the parts above the furnace, i.e., the electrode
holders, the hangers, the current conductors, the charging equipment,
etc., are exposed to the radiant heat of the furnace and tne not furnace
gases. These components must receive effective heat protection through
the use of cooling water flowing through interior passages in the metal
parts. In some reduction furnaces that produce ferroalloys water-cooled
covers having gas removal equipment are built over tne top of the
furnace crucible. In such furnaces raw materials are used tnat do not
tend to bridge and block the flow of gas so that it is not imperative to
22
-------
work the charge with stoking rods. To reduce the bridging problem, raw
materials may be pretreated.
The crucible of the submerged-arc furnace consists of a sealed metal
shell adequately supported on foundations with provisions ror cooling
the steel shell. The bottom interior o± the s-ceel shell is linea with
two or more layers of carbon blocks ana tightly sealed with a carbon
compound packed between the joints. The. interior walls or trie furnace
shell are lined with refractory or carton brick. One or more tap-holes
are provided through the shell at the top level of the bottom carbon
block. In some cases, provisions are made for the furnace to rotate or
oscillate slowly.
Figure 2 shows a diagram of a ferroalloy furnace while Figure 3 snows an
overall cross section of the same furnace with its accessory equipment.
The iron content in the ferroalloy charge material and product greatly
facilitates both its manufacture and use. When metals that melt at high
temperatures are alloyed with iron, the resulting alloy has a lower
melting temperature than the metal with the high melting point. The
lower melting temperature greatly facilitates the furnace production of
ferroalloys and also facilitates its solution in molten steel or iron.
In the submerged-arc furnace the conversion of electrical energy to heat
takes place by current flow from the electrode tips to the riearth and
between electrodes. Final reduction of the oxidic ores occurs in the
lower portion of the furnace.
Submerged-arc furnaces generally operate continuously except ror periods
of power interruption or mechanical breakdown of components. Operating
time averages 90 to 98 percent. The electrodes are submerged from .9 -
1. 5 m (3-5 ft.) below the mix level, and their tips are .Located about .9
- 1.8 m (3-6 ft.) above the hearth. The electrodes' position thus
facilitates both heat exchange and mass transfer between reaction gases
and the mix.
High temperatures, up to 2000°C (3632°F), are required to effect
reduction reactions. Carbon monoxide is a necessary byproduct of the
smelting reaction. In the case of silicon metal, about 2 kg (U.4 Ib) of
carbon monoxide are produced for each kg (2.2 Ib) of metal; significant
amounts of silicon monoxide are also produced as an intermediate.
Although furnaces may be changed from production of one product group to
another, such as from ferromanganese to ferrcchromium, tnis may entail
rearrangement of electrode spacing and different power loads and voltage
requirements. It may also reduce the efficiency of the rurnace
operation, since most furnaces are designed to produce one type of
alloy. However, it is relatively easy to switch from ferromanganese to
silicomanganese, for example, since they are in the same product group.
23
-------
Figure 2 .
SUBMERGED-ARC FURNACE DIAGRAM
REACTION
GASES
ELECTRODES
.1.
A
CHARGE
.— MATERIAL
REFRACTORY
LINING
MOLTEN FERROALLOY
CARBON HEARTH
' l\' I I 1 I I I I 1 II
k-CRUCIBLE
CARBON
CARBON —'
24
-------
CROSS SECTION OF OPEN FURNACE
(f}
NJ
Ul
TAPPING FLOOR -
CRANE FOR PASTE 4
CASING HANDLING
I'ITTII I II 1 1 I I I I I II ITTI I 1 I ! I I I ITI I I I I I ITTT1
GAS
OFFTAKE
SUPERSTRUCTURE
OPERATING
-------
The molten alloy from the carbon reduction of the ore accumuiares at the
base of the electrodes in the furnace. The molten alloy is periodically
removed through a tap-hole placed to drain the 'metal from the hearth of
the furnace.
FERROSILICON PRODUCTION
Quartz and quartzite are the minerals mostly used for smelting
ferrosilicon. The ores should contain not less than 98 percent SiO2_ and
the lowest possible content of alumina, magnesium oxiae, calcium oxide,
and phosphorous. The reducing agent usually used is cOKe; other
reducing agents are coal, petroleum coke, and charcoal. Tne reducing
agent should have minimum ash and phosphorous conttnt. The iron-
containing substance should be clean, carbon steel scrap or pelletized
iron ore; the chromium and phosphorous contents should be low. These
requirements preclude the use of stainless scrap and cast iron scrap.
A material balance for the production of
as shown in Table 10.
50/t ferrosilicon is rypically
Table 10. MATERIAL BALANCE FOR 50*- FERPOSILICON
(% of material charged)
Quartzite
Coke
Steel Shavings
Electrode Mass
47.2
27. <4
24.5
_ 0^9
100.0
Output
Alloy
Volatilized
41.8
58.2
100.0
The charge materials for the production of silicon metal snould contain
no iron. Petroleum coke or charcoal is used as the reducing agent and
pre-baked carbon electrodes are generally used. Power consumption
increases with increasing silicon content of the product rrom 50* FeSi
to silicon metal.
Ferrosilicon is usually smelted in 3-phase electric furnaces which may
be rated at over 40 mw. Modern ferrosilicon furnaces are equipped with
continuous self-baking electrodes and automated charging machinery. The
electrodes are sheet steel cylinders which are filled with the electrode
paste, made of a mixture of anthracite, coke and other carbonaceous
substances, and a mixture of coal tar and pitch used as a binder. The
26
-------
electrode is consumed during the furnace reduction process and is
periodically slipped into the furnace to compensate for its consumption.
The charge materials are prepared in charge ya.ras, transported by
conveyors to the proportioning floor, and distributed among tne furnace
hoppers. From the hoppers the charge is feet into tn<= rurnace charge
holes. During the production of ferrcsilicon, the furnace operates
continuously and the rnetal is tapped as i4: accumulates. Six to eight
tappings per shift are made. After tapping is finished as indicated by
the appearance of flame at the. tap hole, £:lugs consisting of electrode
mass or a mixture of fire clay and coke dust are rammed in.
FERROMANGANESE PRODUCTION
Electric furnaces similar to those used for the production of
ferrosilicon are used to produce ferromanganese. When ferromanganese is
produced from its or-s, iron, manganese, silicon, priosphorous, and
sulfur are reduced and complex iron and rnanqanese carbides are formed.
Smelting is continuous with metal and/or slag being tapped every 2-4
hours.
Ferromanganese is produced in the electric furnace by eitner tne flux
process or the self-fluxing process. The self-fluxing process is
commonly used in the United States. In the flux process, lime is
introduced in the charge; MnO which forms silicates with tne silicon in
the ore and coke dust ash is displaced by calcium oxide, reducing losses
of manganese to the slag. Phosphorous in the ore is mostly reduced and
passes into the alloy. Up to 90% of the phosphorous in tne ore can be
reduced; the reduced phosphorous partially evaporates ana escapes from
the furnace while 60% of the total phosphorous in the cnarge passes into
the alloy. Of the total sulfur introduced in the charge l/s> passes into
the alloy, 40-45% passes into the slag, and 555t escapes with the gases.
The normal charge to produce high-carbon ferromanganese by the flux
method is as in Table 11. The charge-to-alloy ratio is about 4.0.
Table 11. HC FERROMANGANESE CHARGE MATERIALS-FLUX METHOD
(% by weight)
Manganese ore 64.7
Coke 18.0
Limestone 16.8
Electrode mass 0.5
TooTo
27
-------
In the self-fluxing method of producing ferromanganese, little or no
lime is introduced in the charge; the slag is subsequently used to smelt
silicomanganese. By this method, 60% of the manganese in the ore passes
into the alloy, 8-10% escapes, and 30-32$ passes into the slag; 70% of
the manganese in the slag is extracted when siiicomanganese is
subsequently produced from the slag.
The normal charge to produce HC ferromanganese by the self-fluxing
method is shown in Table 12. Of the charged materials, 30.9% pass into
the alloy, 29.5% pass into the slag, and 39.6% escapes as gas and dust.
The gas contains 65-70* CO.
Table 12. HC FERROMANGANESE CHARGE MATERIALS -
SELF-FLUXING METHOD
(% by weight)
Manganese ore (48% Mn) 74.8
Lime 4.6
Coke 20.0
Electrode mass 0._6
100.0
Medium-carbon and low-carbon ferromanganese differ from high-carbon
ferromanganese by their reduced carbon contents and are produced by a
special process. Production in an electric furnace is usually by the
silicothermic reduction method. The charge for MC ferromanganese is
composed of silicomanganese, manganese ore, and lime, as shown in Table
13. The charge-to-alloy ratio is about 3.5.
28
-------
Table 13. MC FEFROMAKGANESE CHARGE
(ft ty weight)
Manganese ore 43.6
Lime 24.3
Silicomar.ganese (20* Si, 65? Mn) 31.2
Electrode Mass 0.9
100.0
A similar charge would be used to produce LC ferromanganese, but using
silicomanganese with a higher silicon, lower carbon content
(ferromanganese-silicon).
SILICOMANGANESE PRODUCTION
Silicomanganese is also produced in electric submergea-arc rurnaces.
The charge is continuously leaded and slag and metal are tapped 3 to 4
times during an 8-hour shirt. Siliccmangariese may jjt smelted from
manganese ore, from self-fluxing slag from, ferrcnianganese production, or
from a combination of both.
A typical charge to produce silicomanganese is shown in Taule 14.
Table 14. SILICOMANGANESE CHARGE MATERIALS
(% by weight)
Manganese Slag
Manganese Ore
Coal or Coke
Lime
Recycle Scrap
29
-------
Low-phosphorous silicomanganese is produced in a manner similar to that
above except that no manganese ore is used in the charge, only manganese
slag.
FERROCHROMIUM PRODUCTION
Ferrochromium is produced in several grades differing mainly in carbon
content. Careful selection of chrome ores is important in producing
each of the several grades of alloy.
HC Ferrochromium Smelting
In the production of HC ferrochrcmium, the chromium ana iron oxides
contained in the ore are reduced by a carbonaceous reducing agent. HC
ferrochromium is smelted continuously; the charge materials are fed in
small portions, keeping the furnace full while metal and slag are tapped
about every 1 1/2 - 2 hours. Smelting of HC FeCr requires higher
voltages and higher power leadings than are used for most otner ferro-
alloys.
A typical charge for the production of HC ferrochromium, normally 60-68%
chromium, is shown in Table 15. The charge-to-alloy ratio is about 4.0.
Table 15. CHARGE MATERIALS FOR HC FERROCHROMIUM
(% by weight)
Chromium ore 72.4
Coke 14.7
Quartzite 6.6
Bauxite flux 5.5
Electrode mass 0_.8
100.0
The charge elements pass into the smelting products as shown
in Table 16.
30
-------
Table 16. RAW MATERIAL COMPONENTS TO SMELTING PRODUCTS FOR
KC FeCr
in total charge
Element
Chromium
Iron
Silicon
Phosphorous
Sulfur
to
alloy
90
98
15
60
10
to slacj
6
2
60
20
30
loss
4
-
5
20
60
Ferrochromesilicon Smelting
Ferrochromesilicon is generally produced by the direct metnod. In the
direct method, chromium ore and quartzite are reduced by coke. The
process is carried out in arc furnaces similar to those used in the
production of ferrosilicon.
EXOTHERMIC PROCESSES
The exothermic process using silicon or aluminum, or a combination of
the two, is used to a lesser extent than the submerged-arc process. In
the exothermic process the silicon or aluminum combines with oxygen of
the charge, generating considerable heat and creating temperatures of
several thousand degrees in the reaction vessel. Ihe exothermic process
is generally used to produce higher grade alloys with low carbon
content. Low-carbon and medium-carbon ferrochromium arid iow-carbon or
medium-carbon ferromanganese are produced by silicon reduction. A flow
diagram of a typical silicon reduction process for manufacturing LC
ferrochromium is shown in Figure U, First, chromium ore and lime are
fused together in a furnace to form a chromium ore/lime melt. Second, a
known amount of the melt is poured into the No. 1 reaction ladle
followed by a known quantity of an intermediate molten ferrochrome-
silicon previously produced in a No. 2 ladle. The reaction in the No. 1
ladle is a rapid reduction of the chrome from its oxide and the
formation of LC ferrochromium and a calcium silicate slag.
31
-------
FLOW
Figure A.
SHEET LC FERROCHROMIUM
ELECTRODES
Cr
ORE
ELECTRODES!
COKE
WOOD
CHIPS
FeCrSi
SUBMERGED-ARC
FURNACE
REACTION LADLE
Cr ORE/LIME WELT
OPEN-ARC
FURNACE
REACTION LADLE #1
THROW-AWAY
SLAG
SECONDARY
THROW AWAY
SLAG
PRODUCT
LC FeCr
t 70%Cr
32
-------
Since the slag from ladle No. 1 still contains recoverable chromium
oxide, a second silicon reduction is made in the No. 2 laaie with molten
ferrochromesilicon directly from the submerged-arc furnace. The
reaction in the No. 2 ladle produces the intermediate ferrochrome-
silicon used in the No. 1 ladle reaction. 1C and MC ferromanganese are
produced by a similar practice usir.g a silicon bearing manganese alloy
for reduction.
The reaction in these ladles from the silicon reduction results in a
strong agitation of the molten bath and a rise in temperature. The
elevated temperature and agitation produces emissions for about five
minutes per heat that have similar characteristics to tht emissions from
submerged-arc furnaces.
ALUMINUM REDUCTION
Aluminum reduction is used to produce chromium metal, rerrotitanium,
ferrovanadium and ferrocolumbium. Although aluminum is a more expensive
reductant than carbon or silicon, the products are purer. Mixed
aluminothermal-silicothermal processing is used for trie production of
ferromolybdenum and ferrotungsten. Usually such alloys are produced by
exothermic reactions initiated by an external heat source ana carried
out in open vessels. The high-temperature reaction or aluminum
reduction produces emissions for a limited time similar to those by
silicon reduction.
SLAG PROCESSING
Some of the electric-arc smelting processes produce slag along with the
ferroalloy product. These are:
Low-carbon Ferrochromesilicon
High-carbon Ferrochromium
High-carbon Ferromanganese
Silicomanganese
These slags may contain metal entrapped in the slag wnicn is recovered
by crushing and separation of the slag and metal by a wet sink-float
process, called slag concentration. The slag fines are also separated
from the heavier particles so that a secondary product is slag of such
size that it is usable for road building and similar purposes. This
process is usually applied to ferrochromium slags for recovery of
chromium which is re-charged to the furnace.
Another method of recovering metal values from manganese slag is to
"shot" the slag, then use the slag as the raw material for electrolytic
production of the metal. Rapid quenching of the molten slag in a large
volume of flowing water produces a small-sized particle (shot) wnich can
be readily leached with acid to produce the electrolyte solution for
electrolytic manganese production.
33
-------
VACUUM AND INDUCTION FURNACE PROCESSES
The vacuum furnace process for producing LC ferrochromium was developed
commercially in the early 1950's. In this method, carbon is removed
from HC ferrochromium in a solid state within vacuum furnaces carefully
controlled at a temperature near the melting point of the alloy. Such a
furnace is shown in Figure 5.
The process is based on the oxidation of HC f errochromium Dy tne oxygen
in silica or chrome oxide, with which it has been mixed after crushing.
The CO gas resulting from the reaction is pumped out ox tne rurnace in
order to maintain a high vacuum and to facilitate tne ferrochromium
decarburization. Heat is supplied to the furnace by electric resistance
elements.
Induction furnaces, either low-trequency or high-frequency, are used to
produce small tonnages of a few specialty alloys throuyn remelting of
the required constituents. Such a furr.ace is shown in Figure 6.
PRODUCT SIZING AND HANDLING
Ferroalloys are marketed in a bread rang^ of sizes from pieces weighing
34. 1 kg (75 Ibs.) to granules of 100 mesh or finer, depending upon the
final usage. Ferroalloys are intermediate products, and are usually
melted and blended with molten metal. For this reason, tne rerroalloy
product size is important.
Molten ferroalloys from the submerged-arc furr.aces are generally tapped
into refractory-lined ladles and then into melds or cnills for cooling.
The chills are low, flat iron or steel pans that remove neat rapidly
from the molten pour. After the ferroalloy has cooled to a workable
temperature,it is cleaned of any adhering slag and sized to market
specifications.
The sizing operation consists of breaking the large initial chills by
drop weights or hammers, then crushing and screening tne broken product.
Large jaw crushers, rolls, mills, or grinders for reducing tne product
size and rotating and vibrating screens are used ror this purpose.
Conveyors and elevators move the product between the crushing and
screening operations. Storage bins are provided to hola the finished or
intermediate products.
34
-------
Figure 5.
VACUUM FURNACE FOR FERROALLOY PRODUCTION
u>
171
TO INERT
GAS COOLING
REMOVABLE
END CLOSURE
TO VACUUM
PUMPING SYSTEM
ELECTRICAL
LEADS
CARBON
RESISTORS
i
ftr TIT TT TTT
/ / A / C J\S / / Y / 'IT / / f / / Y / / / / /*./// / /
n
-TRACK
I I
Q LL Cl \ U U
i
-HEARTH
CAR
FURNACE
CHARGE
*
-------
Figure 6.
INDUCTION FURNACE DIAGRAM
t. LADLE
FURNACE
FURNACE
CRUCIBLE
Ul
OPERATORS PANEL
ELECTRICAL LEADS
F-LbCTklCAL SUBSTATION
-------
EMISSIONS FROM SUBMERGED-ARC FURNACES
Since the quantity and composition of the emissions rrom rerroalloy
furnaces have a major impact upon the potential for water pollution in
those plants using wet air pollution control devices, some discussion of
such emissions is appropriate. The conventional subirieigeci-arc furnace
utilizes carbon reduction of metallics in the oxiae ores, and
continuously produces large quantities ot hot carbon monoxide which can
be greater by weight than the metallic product. The CO gas venting from
the top of the furnace carries fume from high-temperature regions of the
furnace and entrains the finer sizea constituents of the mix.
In an open furnace, all CO and otht-r con^oustibles in the iurnace gas
burn with induced air at the top of the charge, resulting in a large
volume of high-temperature gas. In a covered furnace, most or all of
the CO and other gases are withdrawn from the furnace without
combustion.
Properties and quantities of emitted particulates depend upon the alloy
being produced. Except for ejected mix particles from tne furnace the
fume size is generally below two microns (u) and ranges trom 0.1 to 1.Ou
with a geometric mean of 0.3 to 0.6 depending upon tne ferroalloy
produced. In some cases, agglomeration does occur, and tne effective
particle size may be larger. Grain loadings and flowrates are dependent
upon the type of furnace and hooding. Open submerged-arc furnaces have
high flowrates and moderate grain loadings, while covered furnaces have
moderate flowrates and generally high grain loadings. In trie dry state,
the collected emissions are very light and the bulk density varies from
64.1 to 480.6 kgs./cu. meter (4 to 30 pounds per cubic foot).
Silicon alloys produce a gray fume containing a high percentage of
primarily amorphous silicon dioxide (SiO2|) (Kef. 5). Some tars and
carbon are present arising from the coal, coke, or wood chips used in
the charge. Ferrochrome-silicon furnaces produce an Sio^ emission
similar to a ferrosilicon operation with some additional chromium
oxides. Manganese operations produce a brown emission, which analyses
indicate to be largely a mixture of SiC^ and manganese oxides. The
emissions from chromium furnaces contain SiO^r MgO and some iron and
chromium oxides.
Chemical analysis of the fumes indicate their composition to be similar
to oxides of the product being produced. Typical chemical analyses are
given in Table 17.
37
-------
Table 17. TYPICAL FURNACE FUME CHARACTERISTICS
CO
Furnace product
Furnace type
Fume shape
Fume size char-
acteristics ,
microns
Maximum
Most particles
X-ray diffraction
trace constituents
Chemical
Analysis, %
Si02
FeO
MgO
CaO
MnO
A1203
LOI
TCr as C^Oj
SiC
Zr02
PbO
Na20
BaO
K20
50% FeSi SMZ a
Open Open
Spherical, Spherical
sometimes sometimes
in chains in chains
0.75 0.8
0.05 to 0.3 0.05 to 0
All
FeSi Fe304
FeSi2 Fe203
Quartz
SiC
63 to 883 61.12
14.08
1.08
1.01
6.12
2.10
-
-
1.82
1.26
-
-
-
—
SiMnb
Covered
, Spherical
0.75
.3 0.2 to 0.4
fumes were- prf
Mn304
MnO
Quartz
15.68
6.75
1.12
-
31.35
5.55
23.25
-
-
-
• 0.47
_
-
—
SiMnb
Covered
Spherical
0.75
0.2 to 0.4
FeMn
Open
Spherical
0.75
0.05 to 0.4
• HC FeCr
Covered
Spherical
1.0
0.1 to 0.4
Chrome ore
lime melt
Open
Spherical
and
irregular
0.50
0.05 to 0.2
- Mn ore-
lime melt
Open
Spherical
and
irregular
2.0
0.2 to 0.5
.marily amorphous
Quartz
SiMn
Spinel
24.60
4.60
3.78
1.58
31.92
4.48
12.04
-
-
-
-
2.12
-
—
Mn304
MnO -
Quartz
25.48
5.96
1.03
2.24
33.60
8.38
-
-
-
-
-
-
-
—
Spinel
Quartz
20.96
10.92
15.41
-
2.84
7.12
-
29.27
-
-
-
_
-
—
Spinel
10.86
7.48
7.43
15.06
-
4.88
13.86
14.69
-
-
-
1.70
-
—
CaO
3.28
1.22
0.96
34.24
12.34
1.36
11.92
-
-
-
0.98
2.05
1.13
13.08
Si - 60 to 65%; Mn - 5 to 7%; Zr - 5 to 7%
3
Manganese fume analyses in particular are subject to
wide variations, depending on the ores used.
-------
EMISSIONS FROM EXOTHERMIC PROCESSES
Oxide fumes similar in physical characteristics to -cnose from the
submerged-arc furnace are emitted from the reaction ladle or rurnace
while the reducing agent is being charged during alumino- or
silicothermic reduction. This emission is du<; to strong agitation of
the molten bath and the rapid temperature: rift-. The reaction may take
from 5-15 minutes per heat, and the heat cycle is about 1 1/2 to 2
hours. Therefore, atmospheric emissions fron. the exothermic reactions
take place during about 10 percent of the cycle.
The quantity of emissions from the exothermic reactions ranges from 9.08
to 18.6 kg (20-UO Ibs) of particulars \..*-.r ton of ferroalloys produced.
The total tonnage of ferroalloys rnadt by the exothermic process amounts
to 10 to 15 percent of the total ferroalloys production in the United
States.
OPERATING VARIABLES AFFECTING EMISSION'S
Because of the complexity of the heavy mechanical and electrical
equipment associated with a modern submerged-arc lurnace, close
supervision and maintenance are required to prevent frequent lurnace
shutdowns. The furnaces are designed t.o operate continuously to
maintain satisfactory metallurgical and thermal equilibria.
Normal furnace shutdowns on an annual basis may average tnree to ten
percent of the operating time and are caused by a wiae variety of
situations. These can be electrode installations, maintenance, repair
of water leaks at electrode contact plates, mix cnute taiiures, furnace
hood or cover failures, taphole problems, eif-cr.ricai or other utility
failures, crane failures, ladle or chill problems or curtailments of
service by the power companies. In general, furnace interruptions are
relatively short i'n duration and usually are not more than several
hours. Following such interruptions, the turnace usually returns to
normal operation with normal emissions in a period of time approximately
equal to the length of the interruption.
Greater-than-normal emissions occur after returning power to the furnace
following a lengthy interruption caused by & major furnace operational
problem. These problems may include electrode failure that makes it
necessary to dig out an electrode stub or to bake at a reduced load for
self-baking electrodes, serious mixture blows of the turnace, metallur-
gical problems that require a furnace burndown to return it to normal
operations, serious water leaks that flood the furnace with water,
furnace hearth failure, major taphole problems, transformer or major
electrical system failures, etc. When starting up a new turriace or one
with a cleaned out hearth, as well as a furnace with a cold hearth after
a long shutdown, heavier-than-normal emissions may last up to a week
before the furnace operates in an optimum manner.
39
-------
The quantity of emissions from submerged-arc furnaces will vary up to
several times the normal emission level over a period of one ro three
percent of the operating time due to major furnace interruptions and, to
a lesser extent, because of normal interruptions.
QUANTITIES OF EMISSIONS
Emissions and emission rates will vary with (1) type of alloy produced,
(2) process (i.e., continuous or batch), (3) choice of raw materials and
pretreatment thereof, (1) operating techniques, (5) furnace size, (6)
maintenance practices.
An example of the varying emissions that result from process changes can
be seen in the manufacturing of silicon alloys. As the percentage of
silicon in the alloy increases, the loss of Sic^ increases, therefore, a
silicon-metal furnace emits substantially more SiO2 fumes than an
equivalent-size 50 Jt f errosi li con furnace.
Emissions from batch-operated open-arc furnaces are periodic. Following
sudden addition of mix containing volatile or reactive constituents
(coal, moisture, aluminum, etc.) to a her furnace crucible, violent gas
eruptions can occur. This is best exemplified by the manganese ore-lime
melt furnace where momentary gas £ low following mix addition can be five
times the average flow. Under these conditions, temperature, dust
loading, and gas flow all peak simultaneously. In contrast, chromium
ore-lime melt furnaces, to which few or no gas-releasing constituents
are fed, are not subject to this violent behavior.
Some of the special alloys are also produced by aluminothermic reactions
without the addition of electrical energy. These reactions also cause
momentary peaks of gas flow with high emission rates.
Volatile materials in the furnace charge may cause rough operation. One
significant contributor to such operation is the presence of fines,
moisture or dense material in the feed. These materials promote
bridging and nonuniform descent of the charge which may cause gas
channels to develop. The collapse of a bridge, causes a momentary burst
of gases. A porous charge will promote uniform gas distribution and
decrease bridging. For some products economics dictates the use of raw
materials with more fines or with more volatile matter than desirable.
Pretreatment of the feed materials promotes smooth furnace operation.
Each of these factors has an effect on the smootn operation of the
furnace, and consequently upon the emissions.
Differences in operation techniques can have a significant effect on
emissions. The average rate of furnace gas production is directly
proportional to electrical input, so that a higher load on a given
furnace normally causes a proportional increase in emissions. In some
cases, emissions increase at a rate greater than the load increase, due
to rough operation and inadequate gas withdrawal.
40
-------
At a fixed load and with the gas geirrration remaining almost constant,
the emission concentration and weight per hour of particuiat.es can vary
by a factor of 5 to 1. Operating with insufficient electrode immersion
promotes increased emissions.
Higher voltage operation tor a given furnace wilx promote higher
electrode positions and increase tht- concentration ana amount of
emissions.
On some operations, especially silicon rr;ital production, the cnarge must
be stoked to break up crusts, cover areas of gas blows, ana permit the
flow . of reaction qases. Therefore, both furnace operations and
emissions can be a function of hew well and hew oiter the rurnace is
stoked.
Maintenance practices significantly affect emissions en coverea furnaces
because accumulation of material under the cover ana in gas ducts
reduces the gas withdrawal capacity of the exhaust system. Plugging of
gas passages in the control equipment results in reduced etticiency of
gas cleaning.
PRODUCTION AND EMISSION DATA FOR FERROALLOY fURNACES
The data in Table 18 summarize pertinent data as to production and
emission factors for submerged-arc furnaces (Fief. 32) .
The data of Table 19 summarize the types of air pollution control
devices used in various ferroalloy furr.dces producing specific products
in the United States.
Some comparisons of the off-gas volume from coverea lurnaces and
controlled open furnaces are shown in Table 20.
Table 20. ILLUSTRATIVE OFF-GAS VOLUMES FROM OPEN
AND CLOSED FURNACES - REF 32.
Product
FeMn
FeSi (65-75%)
SiMn
FeSi (50%)
Closed Furnaces
m./llm.w.
6.16
5.88
5.60
5.04
Open Furnaces
scrm/mw
220
210
200
180
370
521
204
258
13,200
18,600
7,300
9,200
-------
Table 18. PRODUCTION AND EMISSION DATA FOR FERROALLOY FURNACES
NJ
Uncontrolled Participate Emissions
Product
Si 1 very
Iron
50 % FeSi
65-75% FeSi
Si Metal
SMZ
Mn ore/1
CaSi
HCFeMn
SiMn
FeMnSI
FeCrSi
Chg Cr
HCFeCr
Cr ore/1
ime melt
ime melt
kg/kkg alloy Ibs/ton alloy kg/mwhr Ib/mwhr
58
223
458
500-1000
No data
67
672
168
110
158
416
168
168
6
116
446
915
1000-2000
No data
133
1343
335
219
315
831
335
335
11
20.4
40.4
47.2
33-65
No data
37.7
51.7
28.1
22.7
26.3
50.8
28. T
28.1
4.1
45
89
104
72-144
No data
83
114
62
50
58
112
62
62
9
Electric Energy
mwhr/kkg alloy mwhr/ton alloy
2
5
9
15
9
1
13
2
4
6
8
4
4
1
.9
.5
.7
.4
.7
.8
.0
.6
.9
.0
.2
.6
.6
.3
2
5
8
T4
8
1
11
2
4
5
7
4
4
1
.6
.0
.8
.0
.8
.6
.8
.4
.4
.4
.4
.2
.2
.2
Ratio of
Charge
to Product Weight
1
2
4
4
4
3
3
3
3
4
3
4
4
1
.8
.5
.5
.9
.5
.5
.9
.0
.1
.3
.4
.0
.0
.2
-------
Table 19. TYPES OF AIR POLLUTION CONTROL SYSTEMS USED ON AMERICAN FERROALLOY FURNACES
Covered furnaces with withdrawal and
cleaning of unburned gases
Open furnaces with withdrawal and
cleaning of burned gases
Control device
Wet scrubbers
U)
Products
Ferromanganese
50 to 75% Ferrosilicon
HC ferrochromium
Silicomanganese
Control device
Wet scrubbers
Cloth type
filters
Electrostatic
precipitator
Products
50 to 85% Ferrosilicon
Silicomanganese
HC ferrochromium
Ferrochrome-silicon
Silicomanganese
Ferromanganese silicon
75% and higher grades
of ferrosilicon
Silicon metal
Ferrochromesilicon
HC ferrochromium
Ferrochromesilicon
-------
SECTION IV
INDUSTRY CATEGORIZATION
The purpose of the effluent limitation guidelines car. be realized only
by categorizing the industry into the minimum number 01 groups ror which
separate effluent limitation guidelines and new sources performance
standards must be developed. The categorization here is £>eiievea -co be
that minimum, i.e., the least numt.er of uroups having sigiiiricantiy
different water pollution potentials ar.c treatment prcolerris.
I. Open Electric Furnaces with Wet Air £-cllu~ior. Control
Devices
II. Covered Electric Furnaces and Other Smelting
Operations with Wet Air Pollution Ccr.rrcl Devices
III. Slag Processing
IV. Noncontact Cooling Water
In developing the above categorization, the following raccors were
considered as possibly providing some has is for categorization. These
factors include characteristics of individual plants, various production
processes, and water uses.
1. Air Pollution Control Equipment
2. Production Processes
a. Electric Furnace
b. Exothermic
c. Slag Processing
3. Furnace Types
a. Open
b. Covered or Sealed
H. Raw Materials
5. Product Produced
6. Size and Age of Production Facilities .
7. Waste Water Constituents
8. Treatability of Wastes
9. Water Uses
-------
a. Wet Air Pollution Control Devices
b. Cooling Water
c. Electric Power Generation
d. Sanitary Wastes
e. Slag Processing
f. Drainage From Slag or Raw Material storage
Air Ppllutign_Control^Eguipmenr
Air pollution is the major pollution problem in this industry. Much of
the water pollution problem is created by solving air pollution problems
with wet air pollution control devices suet: as scrubbers. Since the
only water pollution potential from an electric furnace, whicn is either
uncontrolled or controlled with a dry air pollution control system (such
as a baghouse), is that from cooling water there is no justification for
including these furnaces with those having wet systems, since any
standard which would be fair to the 'wet1 furnaces, would &e excessively
permissive to the 'dry1 ones, and vice versa. For tnis reason, the
categorization selected is partially based upon trie type of air
pollution control equipment, i.e., wet or dry.
Although another breakdown might be made based upon the types of wet air
pollution control equipment, such as high energy scrubbers,
disintegrator scrubbers, electrostatic precipitat.ors with water sprays,
etc., this would unnecessarily multiply the number of categories and
have too small an effect upon the total pollutant load from this
industry to be warranted.
It should be noted that a 'wet' furnace will receive two allowances for
water pollution, one from either Category I or II depending upon the
type of furnace, and also from Category IV for noncontact cooling water.
A 'dry1 furnace, however, will receive an allowance only from Category
IV.
Production Processes
The various production processes vary markedly in their anility to
pollute water, and this provides an additional basis for categorization.
This basis consists of the differential in raw waste loads and
concentrations between the slag processing operations and the electric
furnace and exothermic processes. The electric furnace and exothermic
processes are dry by nature, although water is used for cooling and
possibly for air pollution abatement. The plant survey data obtained at
an exothermic operation using wet air pollution control methods indicate
that the water use per ton is of the same order of magnitude as that of
46
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covered electric furnaces, and the exothermic operations were -therefore
included with the covered electric furnaces.
Although not properly a ferroalloy production process, slag processing
is performed at many plants to recover r.he residual metal values left in
the slag after smelting, and helps reduce -he solid waste load somewhat
at these plants. This process is intrinsically different from the other
production processes, inasmuch as it is inherently 'wet', ana tnerefore
merits a separate category. Additionally, the 'building block'
approach, such as is used for establishing the allowable plant effluents
herein, requires a separate category since all plants do not use such a
process and the magnitude of the potential wasteload is substantial.
Furnace TyjDes
The types of smelting furnaces were found to provj.ce a basis for
categorization in conjunction with consideration oi water uses and other
factors. The differences between oj_en and covered or sealed electric
smelting furnaces are significant insofar as they relate to trie raw
waste loads and the pollutants present and air pollution control
technologies available for use. The olf-gas volumes from tne two types
of furnaces may vary by a factor of 50 between tne two types of
furnaces, and cyanides are present, in scrubber waters from the covered
types, but not from the open type. The water uses for wet air pollution
control devices may be quite different due to tne aifrerences in the
off-gas volumes. Person's (5) published aata shew a difference in water
circulation with venturi scrubbers of a factor of 2<4 between open and
covered furnaces. The final volume ot water flowing from the scrubbers
on open or covered furnaces may not vary significantly; the plant, survey
data indicate, in fact, that the differences are not great and are
probably more dependent on scrubber type thcxn furnace type. The
recirculation of water at the venturi scrubbers on open xurnaces must be
regarded as a part of the waste wa-^er treatment metnods and is so
specified when effluent limitations for such sources are determined.
Additionally, dry dust collectors are widely used on open furnaces, and
are more common than wet collectors. The converse is true with covered
furnaces. There are only two kncwn examples of dry dust collectors
being installed on covered or sealed furnaces, while the vast majority
utilize wet air pollution controls.
-------
Raw Materials
Depending on the product produced, the raw materials for the smelting
operations vary principally in the types of ores and the proportions of
the materials in the charge. For example, the cnarge for HC
ferromanganese consists of manganese ore, coke, and limestone, wnile the
charge for HC ferrochromium consists of chromium ore, coke, quartzite
and bauxite flux. There are no differences, however, in the raw
materials used in the production of 50?; ferrosilicon, whether it is
produced in an open or covered furnace, although trie coverea furnace
feed materials may require pretreatment. There are, of course,
substantial differences in the charge into electric furnaces and the
feed to slag processing operations.
Pr o du ct _ Pro duced
Categorization by product would result in a large number of guidelines
and standards, since the number of products which can ue produced in a
furnace is fairly large, and many products car be produced in either
open or covered furnaces. Additionally, this method would create
unnecessary problems for the person writing the discharge permit, since
plants are accustomed to changing the product produced in the furnaces
depending upon market conditions. For example, during the last few
years, with a decline in the market for ferrochromium and ferromanganese
products, many plants discontinued cr cut back the production of these
products and converted to other, more profitable oroduct lines. With a
categorization based on product, this would either entail the issuance
of a new discharge permit, or the writing of the original permit to
reflect all the possible variations which may take place.
Size and Age of Facilities
The size and age of production facilities provides no basis for
categorization. This judgement is based largely upon the fact that the
emissions factors for the various products (given in kg (Ib)/rnwhr and
which represent the uncontrolled particulate emissions and upon which
the raw waste water loads are dependent) are not variable by furnace
size. Since effluent loads were based upon units of electric power used
in the furnaces, the factor of furnace size seems to oe eliminated by
the nature of the process. Size of the plant may have some bearing on
the cost of waste water treatment, since obviously it will cost a very
small plant more for treatment per unit capacity than it would a large
one, but this is not so great as to warrant categorization.
Although the older furnaces are not as likely to be controlled for air
emissions, and therefore to require scrubber water treatment, by the
nature of the categorization selected this has been taken into account.
The newer electric furnaces differ from the older ones only in size; the
older furnaces are about 10 mw or less, the newer ones are double or
-------
triple that in size. The essential nature cf the furnace has changed
little over many years, although newer furnaces may utilize somewhat
more water for cooling.
Was te_Water Constituents
The waste water constituents provide a collateral, but not independent
basis for categorization. Suspended solids are tne largest single
constituent of -che waste waters and appear in effluent from ail of the
various processes. Suspended solids obviously result from the use of
wet devices to remove particulates from smelting off-gases. Cnromium,
as another
operations,
recirculated
inhibitors.
in covered
between open
example, is in the effluents from cnromium smelting
chromium slag concentrating operations, ana from
cooling waters when chromates are auaea as corrosion
Cyanides are generated in significant concentrations only
furnaces. This distinction appears in tne airf erentiation
and closed furnaces and is thus no independent basis for
categorization based on waste water constituents.
Treatability^of Wastes
Treatability of waste also provides a collateral, but not independent
basis for categorization, largely for the same reasons tnat the waste
constituents do. The treatment methods consist principally of
coagulation and sedimentation, neutralization ana precipitation,
reduction of chromium, oxidation of cyanides and phenol, and
recirculation and re-use. All of these methods, except tor cyanide
oxidation, are applicable to one extent, or another in all of tne various
types of production operations. Cyanide is found in scrubber water only
from covered furnaces, but such a differentiation is inherent in the
chosen categorization, since covered furnaces are separately considered
for other reasons.
From the standpoint of air pollution control, emissions from open
electric furnaces are fairly easily controlled wita fabric filter
systems, and this method has been commonly used in the inaustry tor this
type furnace. Covered or sealed furnaces, however, in this country are
uniformly controlled with wet scrubbers, although there are two foreign
plants which utilize dry dust collection systems for control of
emissions from covered furnaces.
The use of baghouses, of course, reduces water use to zero insofar as
air pollution controls are concerned, and a smelting furnace shop so
equipped does not fall under the categories based upon furnace type,
only the category for cooling water.
Water Uses
Water uses were judged to be a significant basis for categorization.
The categorization differentiates between processes on the basis on
49
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water use for wet air pollution control devices, for slag processing and
for noncontact cooling. Cooling water is used in all smelting
operations and should be a function of power input to the furnace.
Cooling water can be handled in different ways that significantly affect
effluent heat loads and flow volumes. Cooling system effluents can also
be used as scrubber water makeup. The use of different systems requires
that cooling water be separately categorized so that a "building block"
approach can be used in determining allowable plant effluents.
Electric power is presently generated in very few ferroalloy plants. A
separate category is not. warranted; the guidelines separately developed
for steam electric power plants should be applicable, since, as shown in
the previous section, water use per kwnr is about the same as for power
plants in general. Sanitary wastes are common to all plants, whether
treated on-site or discharged to a municipal treatment plant and no
separate category is needed.
50
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SECTION V
WASTE CHARACTERIZATION
The waste characteristics to be determined may be considered on the
basis of the industry categories and the various water uses ab follows:
1. Cooling Water - Electric Furnace Smelting
2. Water for Wet Air Pollution Control Devices
a. Electric Furnace Smelting
i. Disintegrator-type Scrubbers
ii. High Energy Scrubbers
iii. Electrostatic Precipitator Spray Towers
iv. Steam/Hot Water Scrubbers
b. Exothermic Smelting Processes
3. Sanitary Uses, Boiler Feed, Air Conditioning, etc.
4. Slag Processing Uses
PUBLISHED DATA SOURCE CHARACTERIZATIONS
A total of 2,329,630 kxgs (2,568,500 tens) of ferroalloys were produced
in 1967, using 11,206 million kw-hrs. of electric energy according to
the ,1967 Census of Manufactures Of rht total energy used, J,354 million
kw-hrs. were generated by ferroalloy plants. Assuming miscellaneous
losses and other uses of 15 percent, an average use of 4,Ub9 x.w-nrs. per
kkg (3,709 kw-hrs. per ton of alloy in terms of rurnace power is
indicated.
Total water intake for S.I.C. 3313 plants was 1128.7 X 109 liters (298.2
X 109 gals.) per year according to the 196_7_Cen.s_us_cf_Manu£.aCturfc3 while
gross water use was 1212.3 X 10* liters (320.3 x 109 gals.). Intake for
cooling was 381.5 X 109 liters (IOC.8 X 109 gals.). Assuming that all
water recirculation and reuse was for cooling, cooling water use was
465.2 X 109 liters (122.9 X 109 gals.) Cooling water use of 199,679
liters per kkg (47,849 gal. per short ton) of alloy, or 4a.8 liters
(12.9 gals.) per kw-hrs. of furnace power is indicated.
The J_96_7 _Cens_us _of_ Manufactures indicates a water use of 701.4 X 109
liters (185.3 X 109 gals.) of water in generating tne aforementioned
3,354 million kw-hrs. of electric energy in-plant. The indicated use of
208.9 liters (55.2 gals.) per kw-hrs. is about equal to the 1964 thermal
electric power plant use of 215 liters (56.8 gals.) per kw-hr. (Final
Report, EPA Contract 68-01-0196). Assuming losses and otner uses at 15
percent, a water use of 245.6 liters (64.9 gals.) per kw-nr. of rurnace
power is indicated for in-plant power generation.
The 1967 census data indicate a use of 40.9 X 109 liters (10.8 X 109
gal.) per year for sanitary, boiler feed, air conditioning, and other
minor uses and plant employment of 8,700. At 378.5 liters (100 gals.)
per capita per day, 250 days per employee per year, sanitary use would
51
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have been 825 X 106 liters (218 X 106 gals.) per year; air conditioning
use was 757 X 10* liters (200 X 106 gals.) per year. These uses total
4.28 liters (1.13 gals.) per kw-hr. of furnace power, assuming losses
and other uses at 15 percent.
Person's data (5) indicate the water use in high energy scrubbers on
open furnaces as 113.6 I/sec (1,800 gpn.) for each of three furnaces
producing FeCrSi, SiMn, and HC FeCr ar.d rated at 25, 30 and 30 mw,
respectively. At an assumed operating load of 75% with 95% operating
time, the indicated water use is 1,226,340 liters (324,000 gals.) per
60.6 mw-hrs., or 20,238 liters (5,347 gals.) per mw-hr. of furnace
power.
Person's data further indicated an average use of. 5.5 I/sec (87.5 gpm)
for a high energy scrubber on a semi-closed 45 mw 50* FeSi furnace. At
95% operating time and 75% operatincr load, the indicated water use is
620.7 liters (Ifa4 gals.) per mw-hr. of furnace power.
According to Retelsdorf, et.al. (6) an electrostatic precipitator
installed on a 20 mw ferrochromesilicor. furnace uses water in a spray
tower preceeding the precipitator at the rate of about 9,084 liters
(2,400 gals.) per hour. This indicates a use of 635.9 liters (168
gals.) per mw-hr. of furnace power at 959? operating time and 75%
operating load. About 10-15 % of the water used is discnarged from the
bottom of the spray tower, the remainder being evaporated into the gas
stream. These data indicate about 556.4 liters (147 qals.) o± water per
mw-hr. of furnace power evaporated in the gas stream.
From the above data and those given in Section III, some limited
calculations of waste characteristics may be made.
Cooling water volumes for electric furnaces would be expected to be
about 48.8 liters (12.9 gals.) per kw-hr. of furnace power. Once-
through use would be expected to alter such water only to trie extent of
increasing temperatures above the inlet levels. Most industrial cooling
water systems are designed for a change of temperature of 6.6 to 12.0°C
(10-20°F). Recirculated cooling water blowdown may oe expected to
average about 1-2% of the recirculation rate, with 2 cycles of
concentration, i.e., the blowdown will contain twice the concentrations
of constituents in the intake water. Additionally, such blowdowns will
contain chromates or phosphates used for corrosion control, and other
treatment chemicals such as biocides, slime inhibitors, etc.
Assuming that 556 liters (147 gals.) of water per mw-hr. of furnace
power is evaporated in the ga§ streams from open furnaces using wet air
pollution control devices and that such evaporation in the case of
covered furnaces is in proportion to the gas volume, the effluent
volumes expected would be as follows:
52
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High energy scrubbers (open furnace) = 19,682 1/mw-hr (5200 gal/mw-hr)
High energy scrubbers (covered furnace) = 609 1/mw-hr (ibl gal/ mw-hr)
Electrostatic precipitator = 79.5 1/mw-hr (21 gal/mw-hr)
On the basis of the data given in Section III on production processes,
compositions of raw materials, and compositions of products and by-
products, the following constituents/parameters appear to be those
potentially present in waste water:
Acidity Columbium Potassium
Alkalinity Cyanide Padioactivity
Aluminum Dissolved Solids Silica
Ammonia Iron Sulfates
Barium Magnesium Suspended Solids
B. O. D. Manganese Temperature
Calcium Molybdenum Titanium
Chrcmates pH Vanadium
Chromium Phosphates Zirconium
WASTE CHARACTERIZATIONS FROM DISCHAKGh PERMIT DATA
Waste constituents/parameters listed as present, in discharge
permit applications for the plants in S.I.C. 3313 ar- as
follow:
Algicides Fluorides Sodium
Aluminum Hardness Solids
Ammonia Iron Sulfats
Barium Magnesium Sulfide
Boron Manganese Sulfite
Calcium Nickel Surfactants
Chloride Nitrate Titanium
Chromium Oil and Grease Turbidity
Color Organic N Zinc
Copper Phosphorous
Additionally, pH and temperature are given as waste parameters.
WASTE CHARACTERIZATIONS FROM PLANT SURVEY DATA
Waste characteristics were determined where possible from the plant
survey data for various specific waste-producing sources. These data,
of course, apply to the particular units operating as triey were during
the sampling period and represent the type of result to be expected
during the actual operation. To the extent possible, reasons for
variations are explained.
53
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WASTE CHARACTERIZATION
CONTROL DEVICES
- OPEN ELECTRIC FURNACES WITH WET AIR POLLUTION
The data from Plant D provides raw waste loads for
furnaces in which the off^gases are scrubbed
scrubbers as shown in Table 21.
open submerged arc
wirn steam/hot water
Table 21.
RAW WASTE LOADS-OPEK CHROMIUM ALLOY AND
FERROSILICON FURNACES WITH STEAM/HOT WATER SCRUBBERS
Constituent
Suspended Solids
Phosphate
Phenol
Oil
CN, total
CN, free
Iron
Manganese
Zinc
Cr, total
Cr, hex.
Lead
Aluminum
Flow
kcr/mwhr
8.2
.010
.0004
.002
.0001
.00005
.069
.005
.068
.003
.002
.008
.158
Ibs/mwhr
18.1
0.023
0.001
0.004
0.0002
0.0001
0.152
0.010
0.149
0.007
0.004
0.018
0.348
1/mwhr
2, 6 SI
The data from Plant L provide an additional raw waste load tor an
electric furnace using a venturi scrubber, as shown in Table 22.
open
54
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Table 22. RAW WASTE LOAD - HIGH ENERGY SCRUBBFfc
ON OPEN ELECTRIC FURNACE
Constituent
Suspended Solids
Phosphate
Phenol
Oil
Cyanide (Total)
Iron (Total)
Manganese
Zinc
Chromium (Total)
Lead
Aluminum
Flow
venturi scrubber
kcj/mwhr
23.74
0
0.0005
0.006
0
0.041
1C. 06
0. 33
C.002
0. 07
1. 13
1/mwhr
6,382
Ihs/mwhr
52.29
0
0.001
0.014
0
0.089
22. 15
C.72
0.005
0.16
2.49
qals/mwhr
1 ,666
The data from Plant G providing raw waste loads for Oj-tn submerged arc
furnaces in which the off-gases are conditioned in a spray tower
preceding an electrostatic precifitatcr are shown in Tai^le ^3.
Table 23. RAW WASTE LOADS-OPEN CHROMIUM ALLOY
FURNACES WITH ELECTROSTATIC FRECIPITATOkS
Stituent
Suspended Solids
Phosphate
Oil
Iron
Manganese
Zinc
Chromium, total
Aluminum
Flow
269
00001
0001
001
0012
001
0016
0070
1/mwhr
84.0
Ibs/mwhr
0.636
0.00002
0.0002
0.002
0.0026
0.003
O.OC36
0.0155
gals/mwhr
22.2
55
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Although the data as given in Table 23 for water flow agrees quire well
with that predicted (84.0 vs 79.5 1/mwhr) (22.2 vs 21 gal/mwnr) , and the
flow rate from the steam/hot water scrubbers cannot be compared with
anything, the values for flow from the high energy scrubber are about
one-third of that predicted. However, the flow from the nigh energy
scrubber does not take into account recirculation of tne scrubber water
which is done at the scrubber prior to clarification and which may
account for the difference.
WASTE CHARACTERIZATION-COVERED ELECTRIC FURNACES WITH WET
AIR POLLUTION CONTROL DEVICES
The data from Plant B provides information on the waste water from
disintegrator scrubbers operating on covered furnaces producing silicon
alloys. Raw waste loads of suspended solids and cyanides are given in
Table 24 on the basis of the furnace power during the 16-hour sampling
periods.
Table 24. RAW WASTE LOADS FOR COVERED FURNACES
WITH DISINTEGRATOR SCRUBBEES
Suspended Solids Cyanides Flow
Ibs/mwhr kH^mw.hir Ibs/mwhr _l/inwhr gal/mwhr
SiMnZr 20.1
75% FeSi 39.2
50% FeSi 5.1
75% FeSi 6.8
44.3
86.3
11.3
15.0
0338 ,0745
0001
0139
.0002
.0307
8270
8967
8823
7562
2185
2369
2331
1998
The data for the second furnace in Table 24 probably represent reliable
data, since at 75% particulate removal efficiency the suspended solids
load is somewhat higher than are given in the EPA air pollution study
(Ref. 32) data. The remaining data in Table 24 indicate suspended
solids loads much lower than would be expected from tne air emissions
data. This could have either occurred due to poor functioning of the
scrubbers (as evidenced by the lower temperature of the effluent water
and observations of visible stack emissions, sometimes very heavy).
Another possible explanation is that the samples may have ueen taken in
a region where water sprays are used to suppress foaming, and could,
therefore, have been diluted.
The data from Plant C provides raw waste load data tor a sealed
silicomanganese furnace where the off-gases are scrubbed in a spray
tower and a disintegrator scrubber. These data are shown in Table 25.
56
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Table 25. RAW WASTE LOADS-SEALED SIL]
FURNACE WITH DISINTEGRATOR
.CCMANGANESE
SCFUPJ-EF
Constituent
Suspended
Phosphate
Phenol
Oil
Cyanide,
Cyanide,
Iron
Zinc
Chromium,
Lead
Aluminum
Manganese
Flow
solids
total
free
total
kq/rnwhr-
16.6
. 052
.009
.038
.044
.011
. 056
.224
.0004
.033
.413
4. 858
1/mwnr
10,863
Ibs/mwhr
36.
10
b
1 14
019
084
098
0^4
123
493
001
072
91
70
gals/rrwhr
2,87C
The data from Plant E also proviae data on scruhber raw Wctste water
loads from covered furnaces equipped with high energy ar.a disinregrator
scrubbers.
57
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Table 26. RAW WASTE LOAD-CQVERED FURNACES WITH
SCRUBBERS
Constituent
Susp. Solids
Phosphate
Phenol
Oil
Cyanide (Total)
Iron (Total)
Manganese
Zinc
Chromium (Total)
Lead
Aluminum
Flow
4.01
0.004
0.002
0.022
O.OQ7
0.08
0.016
0.21
0.002
0.023
0.07
1/mwjjr
9,746
Ibs/mwhr
8.83
0.008
0.004
0. 048
0.015
0.17
Ol034
0.45
0.004
0.051
6.16
gals/mwhr
2,575
The data from Plant H provide data on the raw waste loads from
aluminothermic production of chromium alloys in which the off-gases are
treated in a combination wet scrubber and baghouse and are given in
Table 27.
58
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Table 27. RAW WASTE LOADS-ALUMINOTHERMIC SMELTING
WITH COMBINATION WET SCKUEEFRS AND EAGHOUSE
Constituent
Suspended Solids
Phosphate
Phenol
Oil
Cyanide (Total)
Cyanide (Free)
Iron (Total)
Manganese
Zinc
Chromium (Total)
Chromium (Hex.)
Lead
Aluminum
Flow
kg/kkg
3.6
0
0
0.048
0
0
0
0.0005
0
2.98
0.95
0
o
I/isisa
26,332
Ib/t on
7.1
0
0
0.095
0
0
0
0.001
0
5.95
1.90
0
g
3£.i§./ton
6,310
Contrary to expectations, the covered furr.aces which
water uses higher than those of open furnaces usi^y
scrubbers. This may be because water use ir: disintegrator
higher, for a particular gas volume, than the water use in
scrubbers. Most of the covered furnaces surveyed ucs=a a
rather than high energy scrubbers. However, ore furnace at
equipped with a high energy scrubber, and the water use on
9572 1/mwhr (2529 gal/mwhr) , so ir would seem that, this ex
not always be valid.
WASTE CHARACTERIZATION - SLAG PROCESSING
surveyed had
high energy
scrubbers is
nigh energy
isintegrator.
Plant E was
ti,at equalled
planation may
The data from Plant E provides information on the raw waste loads from
slag processing operations. That frcm slag concentrating is shown in
Table 28.
59
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Table 28. PAW WASTE LOADS-SLAG CONCENTRATION PROCESS
Congtitugnl
Suspended Solids
Phosphate
Phenol
Oil
Cyanide (Total)
Iron (Total)
Manganese
Zinc
Aluminum
Lead
Chromium, (Total)
Flow
kg/kka
46.
0
0
•
•
w
•
.
*
0
•
1/kkg
0
064
0003
543
245
012
569
109
48,259
Ib/ton
91
0
0
1
1
0
gal^/
.9
.128
.0007
.085
.489
.023
. 130
.217
ton
12,750
No raw waste load can be calculated directly for tne slag shotting
process, since tonnage figures were not given. However, an estimate for
tonnage can be made from production figures. The charge to alloy ratio
is 3:1 for HC FeMn, meaning that three tons of charge materials are
required to produce one ton of alloy. Assuming no losses, this means
that two tons of slag and particulates are. produced for every ton of
alloy. The emission factor for HC FeMn is 335 Ib/tori product, so the
slag produced is two tons minus 335 Ibs = 3665 Ib/ton alloy. This
figure times operating load divided by the electrical energy required
per ton of alloy gives us an hourly production figure for slag of 24,452
Ib/hr. This divided into the water flow rate gives a water use of 8,588
gal/ton processed, a suspended solids raw waste load of 15.5 Ib/ton, and
a manganese load of 3.87 Ib/ton.
WASTE CHARACTERIZATION-rNONCONTACT COOLING WATER . ..
Plant A provides information on the waste water resulting from the
recirculation and reuse of cooling water on electric smelting furnaces
producing silicon alloys and utilizing no wet air pollution control
devices. A softener is used on one cooling water circuit handling about
50 percent of the total cooling water flow. Treatment chemicals are
used with a phosphate reagent used rather than a chrornate. The raw
waste loads are given in Table 29 on the basis of the total furnace
power during the sampling period.
60
-------
Table 29. RAW WASTE LOADS--MONCONTACT CCCLING
WATER—SUBMERGED-ARC FUIxNACHS
Parameter
Suspended Solids
Phosphate
Phencl
Oil
Iron, total
Manganese
Zinc
Chromium, total
Aluminum
Flow
.09
.001
.00005
.002
.001
.0005
.00001
.000005
.002
1/mwhr
502.6
ib£/ir>whr
0.
0.
0,
0.
0.
0.
19
00?
C001
004
002
001
0. CO 00 3
0.00001
O.OOt*
132. 8
The data from Plant F provide raw
recirculation and reuse of cooling war. -i
utilizing chromate treatment for corrosion
30.
loaas resulting from the
en electric smelziny rurnaces
inhir-i-.ion, as snown in Table
61
-------
Table 30.
RAW WASTE LOADS—NONCONTACT COOLING
WATER—SUBMERGED-ARC FURNACES
Parameter
Suspended Solids
Total Iron
Manganese
Zinc
Oil
Total Chromium
Hexavalent Chromium
Aluminum
Flow
I/mwhr
,71
.oil
,007
,14
,08
,26
,0001
,013
1/mwhr
734
Ibs/mwhr
5.98
0.025
0.016
0.30
0. 18
0.58
0.0003
0.03
gals/mwhr
19u
The cooling tower blowdown at Plant D is equal to 35.3 liters (9.32
gals.) per mwhr and the heat load at a temperature rise of 7.2°C (13°F)
is equal to 255 kg-cal (1,010 BTU) per mwhr.
The average cooling water usage found at the plants surveyed was 53,690
1 (14185 gal)/mwhrr at an average temperature rise of 7.6 °C (13.7°F).
62
-------
SECTION VI
SELECTION OF POLLUTANT PARAMETERS
Pollutant parameters have been selected by industry categories on the
basis of those which originate in the production processes in
significant amounts and for which control and treatment technologies are
reasonably available. The parameters fcr each category have also been
selected so as to be the minimum number which will insure control. The
pollutant parameters selected are shown by category in Taoie 31.
Table 31. POLLUTANT PARAMETERS FOR INDUSTRY CATEGORIES
Parameters
II
III
IV
Heat Content
Suspended Solids
PH
Total Chromium
Kexavalent Chromium
Total Cyanide
Manganese
oil
Phenol
Phosphate
-
X
X
X
X
-
X
X
X
X
-
X
X
X
X
X
X
X
X
X
-
X
>.
X
-
-
X
X
-
—
X
X
A"
X
X
-
—
X
-
X
Although effluent flow volumes are not specified in the recommended
guidelines, its measurement and control is inif licit in attaining the
pollutant effluent loads specified. Flow, of course, is a basic
parameter in that its magnitude indicates the degree or recirculation
and reuse practiced and the degree to which water conservation is
utilized. Additionally, flow measurements will be necessary for
calculating treated waste loads for monitoring purposes.
Since noncontact cooling water is extensively used ana the magnitude of
thermal pollution is potentially large, the net heat content is included
as a pollutant parameter for noncontact cooling water. Additionally,
this category requires limitations for chromium ana phosphate, two
common water treatment chemicals used in recirculating systems..
Oil is considered for all categories, since it is a
housekeeping practices, waste stream segregation, etc.
measure of good
63
-------
Suspended solids are primary pollutants resulting from wet air pollution
control devices and slag processing. Suspended solids concentrations
may range up to 7600 mg/1. They appear to a lesser extent in noncontact
cooling water blowdown from recirculating systems. The pri determination
in conjunction with metals determinations indicates that excessive free
acidity or alkalinity has been neutralized after chroruate reduction and
precipitation, cyanide destruction or acid treatment or cleaning in
cooling water systems.
Chromium, manganese, iron, zinc, and aluminum are the principal metals
originating in the production processes. Manganese concentrations may
be as high as 1576 mg/1, while the maximum chromium concentrations found
were 8.36 mg/1 from an electrostatic precipitator spray tower and 121
mg/1 from an exothermic chromium smelting operation. Hexavalent
chromium is additionally included because it may be narmrul at low
levels.
Cyanide is not oxidized in the reducing atmospheres of covered furnaces
and appears in the waste water. It must be considered in view of the
potential danger as with hexavalent chromium. Phenols evidently
originate from electrode binding materials and are considered because of
the taste-and-odor producing potential of even low concentrations of
such compounds. They principally appear in the waste water from covered
furnaces, although some may be present in that from open furnaces. It
would seem that phenols are oxidized in open furnaces, out not in the
reducing atmosphere of covered furnaces.
Phosphate is considered because it has appeared in significant
concentrations in the plant survey data and may be controllable insofar
as it is contributed by process sources.
The pollutant parameters chosen have been those which appeared in
significant concentrations from the sampling and analysis conducted
during the plant surveys, and are those parameters amenable to control.
Other parameters such as dissolved solids, chlorides ana sulfates appear
in effluents in significant concentrations, but largely result from
neutralization, softener regeneration, and water reuse; they are thus a
result of treatment and there would be no logic in attempting to set
limits. Many of the metals contained in the raw waste, particularly
iron, zinc, aluminum, and lead are part of the solids generated in the
smelting furnaces. Plant survey data indicates that tney are controlled
if suspended solids concentrations are controlled.
-------
SECTION VII
CONTROL AND TREATMENT TECHNOLOGY
The water pollution control and -Treatment technology used in the
ferroalloy industry has generally teen sedimentation in lagoons, some of
which are very large. The 8 plants which were surveyed in the course of
the present study covsr the full range of processes used in me industry
and the various levels of control and Treatment technology.
By far the most serious pollution problem to the industry nas been that
of air pollution. Air pollution abatement has been a major concern of
the industry and has involved most of the expenditures lor pollution
control. Air pollution control systems installed, being built, or
planned are generally capable of meeting existing state regulations; in
cases where controls have l:een installed for 5 years or more, such
controls were adequate to meet then-existing regulations, but may be
marginal insofar as newer regulations are concerned.
The plants surveyed are classified in Table 32 in terms OL tn-- industry
categorization given previously.
Table 32. CHARACTERISTICS OF SURVEYED PLANTS
Category Processes and Viater^Uses and .Air controls
A IV Baghou.ses being built, recirculated
cooling water
B II,IV Disintegrator scrubbers, cnce-tnrouga
cooling water usf
C II,IV Sealed furnace, disintegrator scruboers,
recirculated cooling water and scrui^oer water
D I,IV Steam/hot water scrubbers, recirculation of
coolinq and scrubber water
E I,II,III, Disintegrator scrubbers, venturi scrubbers,
IV once-through water use, slag processing
F IV Baghouse/no air controls, recirculated
cooling water
G I,III,IV Electrostatic precipitators, with water
sprays, recirculated cooling water, slag processing
H II,IV Exothermic process, wet scrubbers
and baghouse '
The treatment and control technologies available for this industry's
waste water may be grouped as follows for the principal waste
parameters:
65
-------
Heat Content: Cooling porids^ spray ponds, cooling towers
Suspended Solids: Water recirculatich, lagoons, clarifier-^flocculators^
sand filters
pH: Neutralization
Chromium: Hexavalent chromium reduction, precipitation, sedimentation
Cyanide: Alkaline chlorinatioh, ozonatibn
Oil: Flotation, skimming^ air flotation, agglomeration and riltration
Manganese: Neutralization of acid salts, precipitation, sedimentation
Phenol: Biological oxidation, breakpoint chlorination, activated carbon
Phosphate: Chemical treatment, activated sludge
Cooling ponds are designed to approach the equilibrium temperature at
which the rate of change of energy at the water surface equals zero.
This is, practically speaking, the temperature of the surface waters in
an area and may be about 5.6°C (10°F) above the wet-oulb temperature.
Cooling ponds are capable cf limiting the temperature rise in the
effluent to 2.78°C (5°F) over that of the ambient water (or intake
water, if from a surface body). Spray ponds and cooling towers are
designed to approach the wet-bulb temperature. They are generally
capable of a 5-10°F approach to wet-bulb temperature. Spray ponds
occupy about 10 percent of the area of plain cooling ponds, but cost
about twice as much and entail operating costs for power. Cooling
towers cost more than plain cooling ponds, but occupy comparatively
little area and can be operated to recirculate water with blowaown of 1%
or less of the recirculation rate. Additionally, tney may require as
much as 1.8% of furnace power for their operation. Particularly
difficult water treatment problems may require a blowdown as hign as 5%
of the recirculation rate. Treatment chemicals such as chromates or
phosphates, added to control scaling and corrosion constitute a
pollution sourcei
Water recirculation can be used to initially reduce the volume of water
to be treated for suspended solids removal. Lagoons and clarifier-
flocculators can achieve effluent concentrations of 25 mg/1, when well
operated. Lagoons are less expensive in capital and operating costs,
but ' require much more land area. Sand filters achieve effluent
concentrations of 10-15 mg/1 and are little more expensive than
clarifier-flocculators.
Neutralization is, of course, simply a matter of adding an acid or a
base to achieve a neutral pH. This is most efficiently done with
chemical feed pumps controlled by a pH instrument. A caustic or
66
-------
sulfuric acid solution can be used and pH controlled to witnin + 0.2 of
the desired pH.
Hexavalent chromium is reduced almost instantaneously at pH levels below
2.5 by sulfur dioxide. The pH is then raised with lime to about pH 8.2
and the reduced chromium is settled out. with proper operation, the
hexavalent chromium should be completely reduced. Tne effluent
concentration of total chromium depends upon good pH control and
adequate sedimentation. Cyanide is oxidized rapidly to the less harmful
form of cyanate at a pH of 10.5 by alkaline chlorination. Cyanate is
oxidized to CO2_ and N£ by continued chlorination at a pH of about 7.0
and a reaction time of about 60 minutes. Ozonation is an alternate
method for the destruction of cyanide.
Oil is generally removed from waste water by flotation in lagoons or
clarifiers and the floated oil is skimmed off. Air flotation can also
be used with chemical additions to break emulsions ana agglomerate the
oil.
Manganese and iron, to the extent tney are present as dissolved salts,
are removed by neutralization of the acid salts, at a pH above 9.5 for
manganese and above about 8 for iron. This is followed Ljy precipitation
and sedimentation. Ferrous hydroxide, in particular, forms a gelatinous
precipitate which settles slowly. Sufficiently high pH, adequate
sedimentation, and oxidation is required for low effluent
concentrations.
Phenol can be oxidized biologically or chemically by cnlorine and
chlorine dioxide. Chlorine dioxide must, of course, be generated on-
site. Phenol can also be removed by absorption on activated carbon.
Biological oxidation may be unfeasible for this industry with its
generally low BOD levels, although it may be usable ir nutrients are
aided. Activated carbon absorption is a possibility, as is breakpoint
chlorination.
Phosphate can be removed with the use of coagulents such as lime, iron,
or aluminum salts (such as are present in scrubber waste water). Such
treatment is particularly effective if the waste water is further
treated in an activated sludge process. Although an activated sludge
treatment is probably not feasible on ferroalloy waste water, since it
requires other nutrients than phosphates, a pH level of 10-11 will
effect phosphate removals of 80-90% if lime, iron or aluminum salts are
present.
The treatment processes discussed here are conventional. Tnere does not
appear to be any particular need for more advanced treatment methods.
The main problems are the reduction of waste water volumes requiring
treatment to the minimum, design of adequately sized facilities
(particularly for suspended solids removal), proper operation
(preferably with instrumental control) , and operator training.
67
-------
The choice of air polluticn control technology is of utmost importance
in affecting waste water volumes. Most open furnaces are utilizing dry
baghouses and, of course, produce no waste water effluent from this
source.
There are only two known examples in the world of dry dust collectors
being used on sealed or covered furnaces,- neither of wnich is in the
United States. The vast majority of covered furnaces use wet scrubbers;
few open furnaces use wet systems. Some operations (such as exothermic)
may require the use of such novel air systems as a wet baghouse.
[Where a dash is shown under net concentration in Tables 33-91, except
for those tables for intake water, no analysis was made for that
parameter. Where a zero is shown under net concentration, but the
maximum, minimum and average concentrations are represented by dashes,
the parameter concentrations found were below the detectable limit for
that parameter. In other cases where the net concentration is zero, it
is because the average concentration is the sam'e as or less than that of
the intake water. ]
68
-------
PLANT A
This plant, was built in 1952 with five 10 mw submerged-arc open
furnaces; at the time of our visit, three of these furnaces were still
operating. A 35 mw furnace was built in 19fc8, and a 20 mw furnace is
currently under construction. The large furnace produces 50-854 FeSi.
The other furnaces produce 50* FeSi, proprietary silicon oase alloys,
and a rare earth silicide.- Chromium alleys have been produced in the
past. No wet air pollution controls are used; bagiiouses are being
installed. The water use system is as shown in Figure 7.
All plant water is supplied from wells and the furnace cooling water is
recirculated. The No. 1 cooling tower was huilt in 1952 and serves the
three 10 mw furnaces. It is being automated and mouified to include
softeners and strainers, similar to the No. 2 cooling tower. The No. 2
cooling tower was built in 1968 to serve the. 35 mw furnace. Proprietary
treatment chemicals and sulfuric acid are use-d in each system. Blowdown
from the No. 1 tower is manual and from No. 2 tow^r is automatically
controlled by total solids levels. A softener is usea in trie No. 2
tower system with bulk salt used as a regererart. Recircuiated flow in
the No. 1 tower system is 227 I/sec (3600 gpm) and can be increased to
341 I/sec (5400 gpm) if required by cooling needs. kecirculation flow
in the No. 2 tower system is 284 I/sec (450C gpm). The total furnace
power during the sampling period was 48.1 mw. The cooling water use was
thus 38.2 liters (10.1 gals.) per kwhr. Other furnaces exist in the
plant, but have not been recently operated, and there are no plans to
reactivate them. The treatment facilities consist oni> or a settling
lagoon insofar as removal of constituents from the cooling tower blow-
down and miscellaneous yard drainage is concerned.
A storm sewer had been installed to by-pass storm run out originating in
the hills behind the plant. This has reduced the wer. weather flow
through the treatment lagoon.
Summarized data from the plant survey are shown for various sampling
points as designated in Figure 7 in Tables 33 through 37. The
temperature drop across cooling tower No. 1 was determined to be 6.7°C
(12°F). The operating power on the furnaces served by tnis tower during
the sampling period was 21.9 mw.
69
-------
Figure 7.
PLANT A WATER AND WASTEWATER SYSTEMS
DRAINAGE
FURNACE
"COMPENSATE
BACKWASH
STORM
SEWER
TO
RIVER
WATER
ORE FIELD ,,
DRAINAGE
YARD
DRAINAGE
LABORATORY
DRAINAGE
YARD
DRAINAGE
+ v r >
SEPTIC
SYSTEM
OVERFLOW
VARIES
-------
Table 33. ANALYTICAL DATA -SP A- PLANT A
LAGOON INFLUENT
Concentrations, mg/1 (except as noted)
Constituent
Suspended Solids
Total Chromium
Hexavalent Chromium
Total Cyanide
Free Cyanide
Manganese
Oil
Iron
Zinc
Aluminum
Phenol
Phosphate
Lead
pH (units)
Average Flow
Minimum Maximum
50
0.01
_
—
-
1.08
1.8
0.99
0.07
0.33
0.07
1.29
-
5.4
= 10.1 I/sec
440
0.01
_
—
—
1.08
6.4
1.78
0.07
0.33
1.00
3.09
-
7.6
. ( 106
Average
183
0.01
_
_
—
1.08
4.3
1.39
0.07
0.33
0.40
2.42
—
6.7
gpm)
Net Averaae
170
0.01
_
0
0
0.76
3.5
1.36
0.03
0.33
0.06
2.34
0
-
Table 34. ANALYTICAL DATA -RP L- PLANT A
LAGOON "EFFLUENT
Concentrations, mg/1 (except as noted)
Constituents
Suspended Solids
Total Chromium
Hexavalent Chromium
Total Cyanide
Free Cyanide
Manganese
Oil
Iron
Zinc
Aluminum
Phenol
Phosphate
Lead
pH (units)
Minimum
20
—
_
-
-
0.91
1.4
1.71
0.05
—
0.34
1.01
—
5.7
Maximum
440
0.01
_
-
-
1.15
58.6
2.06
0.06
—
0.71
1.35
—
7.6
Average
73
—
_
-
-
1.07
25.9
1.85
0.05
-
0.49
1.12
—
7.0
Net Average
60
0
0
0
0
0.75
25.1
1.82
0.01
0
0.15
1.04
0
Average Flow =10.1 I/sec. ( 106
Average Temperature =13.3°C (56 °F)
71
-------
Table
ANALYTICAL DATA -SP OPLANT A
COOLING TOWER #2
Concentrations , mg/1
Constituent Minimum Maximum
Suspended Solids
Total Chromium
Hexavalent Chromium
Total Cyanide
Free Cyanide
Manganese
Oil
Iron
Zinc
Aluminum
Phenol
Phosphate
Lead
pH (units)
Average Flow =
34
0
0
0
0
0
5
6
38
-
.32
.4
.23
.03
—
.04
.26
-
.9
I/sec,
-
0.
1.
0.
0.
—
0.
5.
-
7.
32
0
36
08
57
79
8
(except as
Average
36
0
0
0
0
0
5
7
—
-
.32
.7
.30
.05
—
.22
.47
-
.3
Net
23
0
0
0
0
0
0
0.
0.
0
0
5.
0
noted)
Average
27
01
39
. ( gpm)
Table 36 ANALYTICAL DATA -SP^ - PLANT A
COOLING TOV7ER #1
Concentrations, mg/1
Constituents
Minimum
Suspended Solids 14
Total Chromium
Hexavalent Chromium
Total Cyanide
Free Cyanide
Manganese
Oil
Iron
Zinc
Aluminum
Phenol
Phosphate
Lead
pH (units)
-
0.
0.
0.
0.
—
0.
4.
—
6.
53
4
34
03
07
47
6
(except as
noted)
Maximum Average Net Average
500
-
0.
0.
0.
0.
-
0.
5.
-
8.
53
8
38
055
57
26
3
183
0
0
0
0
0
4
7
-
-
.53
.6
.36
.039
-
.31
.83
-
.4
170
0
0
0
0
0
0
0
0
0
0
4
0
.21
.33
.75
Average Flow = 1.55 I/sec.. ( -24.6 gpm)
Average Temperature =15.6°C (60 °FJ
72
-------
Table
27.
ANALYTICAL DATA -SPf.~ PLANT
WELL WATER
Constituent
Suspended Solids
Total Chromium
Hexavalent Chromium
Total Cyanide
Free Cyanide
Manganese
Oil
Iron
Zinc
Aluminum
Phenol
Phosphate
Lead
pH (units)
Average Flow =
Concentrations, mg/1 (except as noted)
Minimum Maximum Average Net Average
8
0.32
0.6
0.022
0.30
6.9
16
0.32
1.0
0.06
0.07
0.41
0.14
7.7
13
I/sec. (
0.32
0.8
0.03
0.044
0.34
0.08
7.3
gpm)
Table 38. ANALYTICAL DATA -SPA- PLANT B
INTAKE WATER
Constituents
Suspended Solids
Total Chromium
Hexavalent Chromium
Total Cyanide
Free Cyanide
Manganese
Oil
Iron
Zinc
Aluminum
Phenol
Phosphate
Lead
pH (units)
Average Flow =
Concentrations, mg/1 (except as noted]
Minimum Maximum Average Net Average
0.018
0.4
1.31
0.02
38
0.016
0.018
1.5
1.37
0.02
20
0.005
0.018
0.8
1.34
0.02
0.23 0.23 0.23
6.5 7.7 6.9
353 I/sec. (5,600 gpm)
73
-------
PLANT B
This plant has been operating since 1939 and has four covered submerged-
arc furnaces producing 50% ferrosiliccn, 75% ferrosilicon and silicon-
manganese-zirconium (SMZ). These furnaces have a total racing of 71.0
mw and operated during the plant survey period at 54.3 mw. Tne water
and waste water system for the plant is shown in Figure 8.
The four covered furnaces use cooling water on a once-through £>asis and
the sewage by the 350 employees is treated at an on-site plant. The
total effluent is 30,282 cu. m/day (8 ir.gd) . Water is drawn rrom a
surface source.
The fumes from the four furnaces are scrubbed using s<=ven Buffalo Forge
(disintegrator) scrubbers, each usino 15.7b I/sec (250 gpm) or water.
During the plant survey, one furnace had only one scrub£»er, each of the
other furnaces had 2 scrubbers; a second scrubber was oeing installed on
the first furnace. The scrubber water is combined at a lift station
where lime and chlorine are added to'oxidize the cyaniaes proauced in
the covered furnaces. . The scrubber water then flews tnrough 2 lagoons
in series totaling 30.5 acres in area and providing 5-6 days retention.
The flow then goes to a clariflocculator where lime and a fldcculant are
added for improved sedimentation. The clariflocculator underflow is
returned to the first lagoon ana the clariflocculator effluent is
treated with chlorine, lime being added if necessary, to destroy
residual cyanides. The clariflocculator overflow effluent then passes
through 2 additional lagoons in series totaling 2.2 acres in area. The
treated scrubber water is then combined with cooling water, sewage plant
effluent, and yard drainage and flows through a final lagoon 0.25 acres
in area. The cooling water temperature averages 8.33°C (15°F) above
ambient. (The plant states that the average temperature rise of the
cooling water is 4-5.5°C (7-10°F)).
The total plant effluent was determined by measurements over a
rectangular weir and the sewage plant effluent was measured by bucket
and stopwatch. The yard drainage flew was estimated. The furnace
cooling water flow was determined by difference and cnecked by a
calculated chloride balance. The discharge permit data for tnis plant
indicated a cooling water flow of 378.6 I/sec (6,000 gpm) and
recirculation of some of this water. There is no chloride buildup and a
low temperature increment in this system. The plant states that there
is no evaporation associated with recirculation, which is done to
increase water velocity in cooling passages. This recirculation may
account for some of the difference between discharge permit data and
that found during the plant survey. In light of the low temperature
increment, however, it is doubtful that 43 & of the cooling water is
recirculated and the flow obtained during the plant survey was judged to
be correct.
-------
The total operating loads on the furnaces during the sampling was 54.3
mw. Summarized analytical data are shown for the sampling points as
designated in Figure 8 in Tables 38 through uu.
75
-------
'Figure 8.
PLANT B WATER AND WASTEWATER SYSTEMS
(Tl
YARD DRAINAGE
FURNACE
COOLING
WATER
SEWAGE TREATMENT
PLANT
4-COVERED ELECTRIC
SUBMERGED ARC
FURNACES
FOR
COOLING
INFLUENT
WATER
7-WET
SCRUBBERS
CHLORINE
LIME
EMERGENCY
OVERFLOW
DISPOSAL LAGOON
2.5 ACRES
• ^ • 1
LIFT
STATION
l
r
DISPOSAL LAGOON
13.5 ACRES
i
t
DISPOSAL LAGOON
17 ACRES
4 '
* V
(r\
i
UNDERFLOW
LIME FLOCCULANT
i i
•, r i ADirinrriii AT/ID
\~/ »^.I_"IMI i-w. VWL.'-H \y i >
OVERFLOW
CHLORINE
pH CONTROL
OVERFLOW
SETTLING LAGOON
0.25 ACRES
SETTLING LAGOON
I.I ACRES
SETTLING LAGOON
I.I ACRES
-------
Table 39. ANALYTICAL DATA -SPB- PLANT B
WET SCRUBBERS
Concentrations, mg/1 (except as noted)
Constituent
Suspended Solids
Total Chromium
Hexavalent Chromium
Total Cyanide
Free Cyanide
Manganese
Oil
Iron
Zinc
Aluminum
Phenol
Phosphate
Lead
pH (units)
Average Flow
Minimum Maximum
968 2,
—
—
1.18
0.20
15.9
2.4
6.1
1.46
0.69
5.62
0.54
1.43
6.2
= 126 I/sec.
242
-
-
3.28
1.57
38.6
7.6
8.9
3.10
1.29
9.05
2.25
1.96
6.4
Average
1,555
—
_
2.49
1.04
24.0
4.5
7.8
2.10
0.99
7.27
1.11
1.71
6.3
Met Average
1,535
0
0
2.48
1.03
24.0
3.7
6.5
2.08
0.99
7.27
0.88
1.71
(2,000 gpm)
Table 40. ANALYTICAL DATA -SPG - PLANT
THICKENER INLET
Concentrations, mg/1 (except as noted)
Constituents
Suspended Solids
Total Chromium
Hexavalent Chromium
Total 'Cyanide
Free Cyanide
Manganese
Oil
Iron
Zinc
Aluminum
Phenol
Phosphate
Lead
pH (units)
Minimum
70
—
- 0.15
0.15
2.58
0.6
0.79
0.94
_
0.43
0.45
6.3
Maximum
96
—
0.36
0.36 ,
2.97
2.2
1.14
1.08
0.29
0.44
0.54
6.9
Average
83
—
0.22
0.22
2.84
1.2
0.95
1.01
0.19
0.43
0.51
6.6
Net Average
63
0 ..
0.21-
0.21
2.82
0.4
0
0.99
0.19.
0.43
0.28
0
Average Flow = 126 I/sec. (2,000 gpm)
77
-------
Table 41 ANALYTICAL DATA -SPD- PLANT B
THICKENER OVERFLOW
Concentrations, mg/1 (except as noted)
Constituent
Suspended Solids
Total Chromium
Hexavalent Chromium
Total Cyanide
Free Cyanide
Manganese
Oil , • J
Iron
Zinc .. '
Aluminum
Phenol ;.
Phosphate
Lead .
pH (units)
Average Flow
Minimum Maximum
8
—
—
0..15
0.15
0.88
1/2
0.41
0.38
' —
0.49
0.27
•_
,8 . 2
=. ( 126
86
0.01
—
.0.34
0.34
0.93
3.0
0.50
0.39
"—
' 0.51
. :0.54
0.05
9., 6
I/sec., (2,000
Average
56
—
—
0.21
0.31
0.90
2.2
0.47
0.38
—
0.50
0.41
0.03
9.0
gpm).. .....
Net Average
36
0
• .0
0 . 20
-."."•' 0..20
" -0/8.8
1.4
0
0.36
0., . .
0.50 ..
.0 . 1.8
0 . 03
' -.-... -.
Table .42 .ANALYTICAL DATA -S.P E - PLANT B
'.., COOLING WATER
Concentrations, .mg/1
Constituents
Suspended Solids
Total Chromium
Hexavalent Chromium
Total Cyanide
Free Cyanide
Manganese
Oil
Iron
Zinc
Aluminum
Phenol .
Phosphate
Lead
pH (units)
Minimum
4
-
0.
-
0.
0.
0.
o..
-
0.
-
6.
006
025
6
044
47
22
7
Maximum
22
0
0
'o
0
0
:0
. 8
-
.061
.025
.8
.044
.47
-
.22
-
.5
(except as
Average Net
11
0
0
0
0
0
0
7
_
.025
-
.025
.7
.044
.47
—
.22
—
.9
0
0 .
0
Q.
^ .0
'"'o.
0
0.
0.
0
0
0
noted)
Average
020
007
024 '
47
Average Flow = 217 I/sec. (3,440 gpm)
78
-------
Table 43. ANALYTICAL DATA -SPF- PLANT B
SEWAGE PLANT EFFLUENT
Constituent
Suspended Solids
Total Chromium
Hexavalent Chromium
Total Cyanide
Free Cyanide
Manganese
Oil
Iron
Zinc
Aluminum
Phenol
Phosphate
Lead
pH (units)
Average Flow =
Concentrations, mg/1 (except as noted)
Minimum Maximum Average Net Average
20
0.01
1.52
1.0
0.33
0.11
0.33
6.31
48
0.01
1.52
2.6
1.31
0.11
0.33
6.31
6.6 7.6
1.0 I/sec. ( 16
32
0.01
1.52
2.0
0.82
0.11
0.33
6.31
7.2
gpm)
12
0.01
0
0
0
1.50
1.2
0
0.09
0.33
0
6.08
0
Table 44. ANALYTICAL DATA -SPG - PLANT B
TOTAL PLANT DISCHARGE
Constituents
Suspended Solids
Total Chromium
Hexavalent Chromium
Total Cyanide
Free Cyanide
Manganese
Oil
Iron
Zinc
Aluminum
Phenol
Phosphate
Lead
pH (units)
Concentrations, mg/1 (except as noted)
Minimum Maximum Average Net Average
10
0.006
0.006
0.20
1.0
0.24
0.08
0.22
0.11
0.30
8.1
70
0.02
0.030
0.020
0.22
2.6
0.28
0.11
0.35
0.12
0.33
9.2
35
C..01
0.020
0.010
0.21
1.6
0.27
0.09
0.30
0.12
0.31
8.5
15
0.01
0.015
0.010
0.19
0.8
0
0.07
0.30
0.12
0.08
0
Average Flow = 350 I/sec. (5,556 gpm)
Average Temperature =20.8°C (69.3F)
79
-------
PLANT C
This plant was built in 1967 and has a single sealed furnace rated at 33
mw. The principal product is silicomanganese.
The water use and waste treatment system is shown in Figure 9. The
furnace off-gases are scrubbed in a spray -ower and a low energy
(Dingier) scrubber. Water is recycled and reused in both the scrubber
system and the furnace cooling water system; the latrer incorporates a
cooling tower. Makeup for the scrubber system is attained from blowdown
from the cooling water system. The scrubber effluent is treated with
potassium permanganate to oxidize the cyanides and a flocculant aid to
improve sedimentation in the thickener .to which all or the scrubber
water flows. The thickener overflow is recycled to the scrubbers and
the underflow is treated in a series of 2 lagoons. Tiie effluent of
these lagoons and the cooling tower blowdown are combined and flow
through 2 additional lagoons in series. The sanitary sewage is treated
in a package-type plant and allowed to settle in a small lagoon before
being combined with the industrial waste water for discharge. The
cooling tower recirculation rate is 163 I/sec (2580 gpm). The
temperature drop across the cooling tcwer is 1U°C (25.2°F).
Summarized analytical data are shown for the designated sampling points
in Tables U5 through 51.
80
-------
Figure 9.
PLANT C WATER AND WA.STEWATER SYSTEMS
CO
COOLING
TOWER
QWEUSQ
BLOW/gsDOWN
POLYELECTROLYTE
REFUSE
WATER
TANK
i
k
fe
SCRUBBER
KMn04
~CH
^
'-*
i
i_
DISCHARGE
...EMERGENCY
F;~*OVERFLOW
ACTIVATED /
CARBON
FILTERS
SANITARY
SEWER
THICKENER
I
LIFT
STATION
I
SANITARY
TREATMENT
PLANT
I
CHLORINE
LAGOON
-------
Table 45.
ANALYTICAL DATA -SP A- PLANT
WELL WATER
Constituent
Suspended Solids
Total Chromium
Hexavalent Chromium
Total Cyanide
Free Cyanide
Manganese
Oil
Iron
Zinc
Aluminum
Phenol
Phosphate
Lead
pH (units)
Concentrations, mg/1 (except as noted)
Minimum Maximum Average Net Average
0.013
0.51
0.021
0.017
0.4
0.51
0.029
0.016
0.2
0.51
0.026
6.9 7.5 7.2
Average Flow = 50.4 I/sec. (800
Table 46. ANALYTICAL DATA -SPB - PLANT
COOLING TOWER BLOWDOWN
Constituents
Suspended Solids
Total Chromium
Hexavalent Chromium
Total Cyanide
Free Cyanide
Manganese
Oil
Iron
Zinc
Aluminum
Phenol
Phosphate
Lead
pH (units)
Concentrations, mg/1 (except as noted)
Minimum Maximum Average Net Average
40
1.37
49
0.6
0.51
3.32
0.14
0.28
7.6
50
3.81
56
1.2
0.68
3.40
0.24
0.95
7.8
45
2.21
52
0.9
0.57
3.35
0.19
0.50
7.7
44
0
0
2.21
52
0.7
0.06
3.32
0.19
0.50
Average Flow =3.1 I/sec. ( 49 gpm)
Average Temperature = 36 °C (96.8 °F)
82
-------
Table
ANALYTICAL DATA -SPC- PLANT
SPRAY TOWER SUMP
Constituent
Suspended Solids
Total Chromium
Hexavalent Chromium
Total Cyanide
Free Cyanide
Manganese
Oil
Iron
Zinc
Aluminum
Phenol
Phosphate
Lead
pH (units)
Concentrations, mg/1 (except as noted)
Minimum Maximum Average Net Average
1,280 2,076 1,529 1,528
0.04 0.04 0.04 0.04
2.46
0.49
271
2.0
3.02
18.9
38
0.70
4.54
1.17
7.6
5.39
1.29
608
4.4
7.91
21.4
38
0.98
5.23
4.00
8.5
4.08
0.99
447
3.5
5.12
20.6
38
0.79
4.77
3.00
8.1
Average Flow =69.3 I/sec. (1,100 gpm)
Average Temperature = 48 °C (118.4°F)
4.08
0.99
447
3.3
4.61
20.6
38
0.79
4.77
3.00
Table 4ti ANALYTICAL DATA -SPD - PLANT c
THICKENER UNDERFLOW
Constituents
Suspended Solids
Total Chromium
Hexavalent Chromium
Total Cyanide
Free Cyanide
Manganese
Oil
Iron
Zinc
Aluminum
Phenol
Phosphate
Lead
pH (units)
Concentrations, mg/1 (except as noted)
Minimum Maximum Average Net Average
8,158 39,012 24,397 24,396
1.99
0.54
8.4
4.90
0.89
3.33
0.68
8.9
8.6
Average Flow = 1.6 I/sec. ( 25 gpm)
Average Temperature = 45 °C (113°F)
3.33
0.68
-------
Table 4£ ANALYTICAL DATA -SPE- PLANT C
SEWAGE PLANT EFFLUENT
Concentrations, mg/1
Constituent
Suspended Solids
Total Chromium
Hexavalent Chromium
Total Cyanide
Free Cyanide
Manganese
Oil
Iron
Zinc
Aluminum
Phenol
Phosphate
Lead
pH (units)
Minimum
2
-
—
-
-
3.
1.
0.
0.
-
0.
-
-
5.
5
0
42
181
04
2
Maximum
8
-
_
-
-
6.
1.
0.
0.
—
0.
-
-
••7
3
6
47
131
29
0
(except as noted)
Average
6
5
1
0
0
0
6
—
_
—
-
.0
.3
.44
.181
—
.17
-
—
.1
Met
5
0
0
0
0
5.
1.
0
0.
0
0.
-
0
Average
0
1
155
17
Average Flow =0.06 I/sec. ( 1 gpm)
Average Temperature = 19.3 °C (66.7 °F)
Table 50 ANALYTICAL DATA -SP.F - PLANT C
SLUDGE LAGOON EFFLUENT
Concentrations, mg/1 (except as noted)
Constituents
Suspended Solids
Total Chromium
Hexavalent Chromium
Total Cyanide
Free Cyanide
Manganese
Oil
Iron
Zinc
Aluminum
Phenol
Phosphate
Lead
pH (units)
Average Flow
Minimum Maximum
106 3
-
_
1.85
0.32
65
1.4
1.11
1.93
9.4
0.15
1.52
-
7.3
= I/sec.
12
-
—
2.41
1.08
97
2.4
1.64
3.11
11.1
0.36
2.23
0.77
7.7
(
Average
188
-
—
2.15
0.77
75.5
1.9
1.30
2.51
10.0
0.23
1.82
0.50
7.5
gpm)
Net Average
187
0
0
2.15
0.77
75.5
1.7
0.79
2.48
10.0
0.23 '
1.82
0.50
84
-------
Table rjl ANALYTICAL DATA -SPG- PLANT c
THICKENER OVERFLOW
Concentrations, mg/1 (except as noted)
Constituent
Suspended Solids
Total Chromium
Hexavalent Chromium
Total Cyanide
Free Cyanide
Manganese
Oil
Iron
Zinc
Aluminum
Phenol
Phosphate
Lead
pH (units)
Average Flow
Minimum Maximum
100 2
_
_
5.01
0.73
51
2.8
0.27
1.00
4.1
0.47
1.02
-
7.2
= 67. 7 I/sec.
52
_
_
6.48
1.12
82
4.0
0.43
2.80
9.4
0.86
4.0
0.80
7.7
(1,075
Average
181
_
_
5.60
0.90
71
3.4
0.38
1.73
6.2
0.64
2.05
0.49
7.5
gpm)
Net Average
180
0
0
5.60
0.90
71
3.2
0
1.70
6.2
0.64
2.05
0.49
Table
ANALYTICAL DATA -SPA - PLANT D
WELL WATER
Concentrations, mg/1 (except as noted)
Constituents
Suspended Solids
Total Chromium
Hexavalent Chromium
Total Cyanide
Free Cyanide
Manganese
Oil
Iron
Zinc
Aluminum
Phenol
Phosphate
Lead
pH (units)
Minimum
10
—
_
-
-
0.20
-
2.24
0.026
_
_
0.02
—
6.1
Maximum
16
—
_
-
-
0.20
-
2.30
0.026
—
_
0.04
—
7.9
Average
13
—
_
-
-
0.20
-
2.27
0.026
-
—
0.03
-
6.7
Met Average
_
—
_
-
-
-
-
—
_
-
_
-
-
-
Average Flow =16.3 I/sec. ( 259 gpm)
85
-------
PLANT D
This plant has open submerged-arc furnaces which produce rerrocnromium,
ferrosilicon, blocking chrome, and ferromanganese. Tnrcc or the
furnaces are rated at 5.5 rr.w and the fourth at 16.5 mw.
These furnaces are equipped witn a. new type cf dust-removal system
utilizing waste heat, from the furnace to provide the clergy for gas
scrubbing without the use of exhaust far.s. This system lias recently
been installed on four ferroalloy furnaces. The reaction gas passes
through a heat exchanger, a nozzle, ar.d a separator. Tne ueat from the
reaction gases is transferred to tht- water in the neat exchanger,
increasing the temperature of the wattr to about 177-204°C (350-4 00°F)
and the water pressure to about 21 kg/sq cm (300 psi) . As trie heated
water is expanded through the r.ozzit of the scrubber, partial flashing
occurs, and the remaining liquid is atoir.iztd. Thus, a two-phase mixture
of steam and small droplets leaves the nozzle at hicm velocity. The
reaction gas from the furnace is -ntrained by this hiyn velocity, two-
phase mixture, and in the subsequent mixing, -he reaction gas is
scrubbed and cleaned. At the same timrf, tb41 action of me gases leaving
the nozzle aspirates the reaction gases from the furnace and propels
them through the system. The. mixture of steam, qas, and water droplets
entrained with the collected parriculat.es frcn< the gas passes through a
separator after discharge from the mixir.a section. The water ana dust
are removed from the gas-steam mixture; tht gas leaves the separator
through the stack, and the water ana dust ere discharged rrom the
separator to a waste water treatment system. Cnemicals and other
treatment are applied to settle the solids and other contaminants from
the water, and the fluid slurry is discharged to settling ponds. This
system is illustrated in Figure 10. The water is then filtered,
softened, and returned to a pump for recycling to tne heat exchanger.
Makeup water is added to replace ar.y losses.
The water flow diagram is shown in Figure 11. The clarifiers consist of
3 inclined, tube-type clarifier-flocculators in parallel. Tne filters
are 3 deep-bed sand filters in parallel; backwash on tne filters is
controlled by a continuously reading turbidimeter. The softener is a
fluidized moving-bed ion exchange unit, rated at 38 I/sec (600 gpm) .
The particular softener design is claimed to minimize resin attrition to
less than 1 percent per year and to minimize rinsewater requirements.
The recirculation rate at the cooling tower is 284 I/sec (4500 gpm), and
the blowdown rate is 1.3 percent, or 3.7 I/sec (5ti.5 gpm). The
temperature change across the tower is 7.2°C (13°F).
During the sampling period, 2 of the smaller furnaces were operating as
was the largest furnace. The products produced were blocking chromium,
ferrochromium, and 50% ferrosilicon. The average daily power
consumption on the furnaces totaled 695.5 mwhr.
86
-------
Summarized analytical data for various sampling poinrs as designated in
Figure 11 are shown in Tables 52 through 57.
87
-------
Figure IO.
STEAM/HOT WATER SCRUBBING SYSTEM
CO
00
OFFTAKE
DUCT
EMERGENCY
STACK
HEAT
EXCHANGER
CLEAN GAS
DISCHARGE
PRIMARY
PUMPS
NOZZLE
MIXING DUCT
SEPARATOR
CLARIFIER
FURNACE
'ENCLOSURE
PUMP HOUSE
-------
Figure I'.
PLANT D WATER AND WASTEWATER SYSTEMS
PP
BLOW DOWN
I L
SCRUBBERS
WELL
MAKE UP TO
SCRUBBERS p
PLANT
DISCHARGE [
.DRY SLUDGE
DUMP
SLUDGE
LAGOONS
CLARIFIERS
FIERS ~1
4 J
FILTERS
BLOW DOWN-
PH
ADJUSTMENT
CELL
BRINE
PUMPS
TURBIDIMETER
CELLS
SOFTENER
BLOW DOWN
-------
Table 5-* ANALYTICAL DATA -SP B- PLANT D
COOLING TOWER SLOWDOWN
Concentrations, mg/1 (except as noted)
Constituent
Suspended Solids
Total Chromium
Hexavalent Chromium
Total Cyanide"
Free ; Cyanide
Manganese
Oil
Iron
Zinc
Aluminum
Phenol
Phosphate
Lead
pH (units)
Average Flow
Minimum Maximum
10
—
_
0.007
-
0.09
0.2
3.08
0.059
0.7
_
1.95
-
6.2
=0.38 I/sec
28
—
—
0.007
-
0.14
0,2
3.15
0.077
0.7
_
2. -77
—
7.8
. ( 6
Average Net Average
19
—
_
0.007
—
0.11
0.2
3.10
0.069
0.7
_
2.54
—
6.8
gpm)
6
0
0
0.007
_
0
0.2
0.83
0.043
0.7
_
2.51
0
Table
ANALYTICAL DATA -SPC - PLANT D
SLURRY BLEND TANK
Concentrations, mg/1 (except as noted)
Constituents
Suspended Solids
Total Chromium
Hexavalent Chromium
Total Cyanide
Free Cyanide
Manganese
Oil
Iron
Zinc
Aluminum
Phenol
Phosphate
Lead
pH (units)
Minimum
768
0.10
0.06
-
-
0.60
-
2.47
11.2
10.8
0.03
0.45
0.68
8.7
Maximum Average Net Average
7,644 3
3.37
1.85
0.062
0.020
4.06
1.3
60.
34.
103.
0.48
6.95
4.4
9.3
,070
1.24
0.68
0.031
0.018
1.89
0.70
27.9
25.1
58.6
0.24
3.95
3.03
9.0
3,057
1.24
0.68
0.031
0.018
1.6'9
0.70
25.6
25.1
58.6
0.24
3.92
3.03
Average Flow =21.6 I/sec. (343.5 gpm)
90
-------
Table 55 ANALYTICAL DATA -SPE- PLANT D
CONTINUOUS SLOWDOWN
Constituent
Concentrations, mg/1 (except as noted)
Minimum Maximum Average Net Average
Suspended Solids
Total Chromium
Hexavalent Chromium
Total Cyanide
Free Cyanide
Manganese
Oil
Iron
Zinc
Aluminum
Phenol
Phosphate
Lead
pH (units)
Average Flow =
8
0.05
0.2
0.39
0.173
0.02
0.04
102
2.24
0.014
0.60
1.6
0.77
0.325
0.6
0.30
0.10
38
0.46
0.005
0,
I.
25
0
0.57
0.175
0.2
0.12
0.06
7.1 11.1 9.6
6.3 I/sec. ( 100 gpm)
25
0.46
0.005
0.05
1.0
0
0.149
0.2
0.12
0.03
0
Table 56 ANALYTICAL DATA -SPD - PLANT
FILTER SUPPLY TANK
Constituents
Suspended Solids
Total Chromium
Hexavalent Chromium
Total Cyanide
Free Cyanide
Manganese
Oil
Iron
Zinc
Aluminum
Phenol
Phosphate
Lead
pH (units)
Average Flow =
Concentrations, mg/1 (except as noted)
Minimum Maximum Average Net Average
68
0.25
0.020
134
0.43
0.029
0.42
0.3
1.53
0.288
0.7
-
0.01
-
9.1
19.2 I/sec
1.23
1.6
6.15
2.51
1.8
0.23
0.18
0.42
10.3
. ( 305
112
0.31
0.024
0.78
1.1
3.15
1.24
1.3
0.12
0.07
0.14
9.7
gpm)
99
0.31
0.024
0.58
1.1
0.88
1.21
1.3
0.12
0.04
0.14
91
-------
DRAFT
Table 57 ANALYTICAL DATA -SPF- PLANT D
PLANT DISCHARGE
Constituent
Suspended Solids
Total Chromium
Hexavalent Chromium
Total Cyanide
Free Cyanide
Manganese
Oil
Iron
Zinc
Aluminum
Phenol
Phosphate
Lead
pH (units)
Concentrations/ mg/1 (except as noted)
Minimum Maximum Average Net Average
60
0.54
0.138
0.014
0.81
0.4
1.06
0.592
532 186
1.35 0.87
0.215 0.177
0.030 0.025
8.4
3.25
0.61
7.83
3.79
0.05
0.10
0.63
9.6
1.81
0.54
3.79
2.03
0.02
0.06
0.21
8.9
173
0.87
0.177
0.025
1.61
0.54
1.52
2.00
0
0.02
0.03
0.21
Average Flow = 9.8 I/sec. ( 155 gpm)
92
-------
PLANT E
This plant has been operating since 1951 ana has principally two areas
where waste waters other than cooling waters are generated and
discharged. These two areas contain electric arc rurnaces and
electrolytic cells, respectively.
There are seven
ferrosilicon,
ferromangan ese,
also contains
furnaces have a
period at 82 mw.
covered and two op=n submer. ged-arc furnaces where 50%
silicomanganese, standard and medium carbon
and high carbon ferrochromiuir, are produced. This area
metals refining and slag shotting operations. These
total rating of 126 mw and operated durine, tne survey
The nine furnaces use cooling water or. a or.ce-tnrougn ijasis.
sanitary sewage -is treated at an on-site plant, and discharges wi~^
cooling water. The total plant effluent is 1.lb X 106 cu. m/day
F whioh •; c; or>ni-i r.i-i u?ater from the plant's
mgd), the majority
mgdj, tne majority
generating station.
The total piant erriu*
of which is cooling
The
with the
(305.5
power
The water
Also shown
survey.
The fumes
energy type
and waste water systems for the plant are enown in Figure 12.
in this figure are tne sampling points usea during the
from the
scrubbers.
furnaces are scrubbed with
There are live venturi and
scrubbers available for
22-32 I/sec (350-500
the nine furnaces. The scrubbers use
gpm) of the water when operating. Tne
either venturi or low-
12 disintegrator type
between
metals
refining operation also utilizes a ver.turi scrubber
scruubcr water
flows via a common line to the rirst cf two lagoons operated in series.
The lagoons have a combined surface area of 78 acres. Trie wasn water
from the electrolytic operations mixes with the scrubber waste water
before entering the lagoons.
The acid waste water frcm the electrolytic operations riows to the
second of these lagoons where a hydrated lime slurry is also added as a
neutralizing agent. This second lagoon also receives the ertiuent from
a flyash removal system at the power plant. The er fluent from the
second lagoon flows to the receiving stream.
A waste water discharge from the slag concentrator flows to a separate
4.3 acre tailings lagoon and then to the receiving stream.
Summarized analytical data for sampling points as designated in Figure
12 are shown in Tables 58 through 74. The 1971 average temperature
increase in cooling water temperatures over inlet was 3.9°C (7°F) .
93
-------
Figure 12.
PLANT E WATER AND WASTEWATER SYSTEMS
CHLORINE
CHLORINE INFLUENT WATER
——-HIFROM RIVER
FOR MISCELLANEOUS
OPERATIONS
VO
' SUBMERGED
ARC - FURNACES
SUBMERGED
ARC - FURNACES
FOR POWER
PLANT
SLUDGE LAGOON NO.)
8.5 ACRES
LIME
SLUDGE LAGOON N0.3
69.6 ACRES
OUTFALL
TO RIVER
OUTFALL
TO RIVER
YARD
DRAINAGE
OUTFALL
TO RIVER
OUTFALL
TO RIVER
OUTFAIL
TO RIVER
-------
Table 58 ANALYTICAL DATA -SPA- PLANT
FURNACE A SCRUBBER DISCHARGE
Concentrations, mg/1 (except as noted)
Constituent Minimum Maximum Average Net Average
Suspended Solids 210 342 261 228
Total Chromium 0.01 0.01 0.01 0
Hexavalent Chromium o
Total Cyanide . - - o
Free Cyanide o
Manganese 54 54 54 54
Oil 1.2 1.2 1.2 1.2
Iron 5.26 5.26 5.26 4.68
Zinc 18 18 18 18
Aluminum 4.45 4.45 4.45 3.78
Phenol 0
Phosphate o
Lead 1.79 1.79 1.79 1.79
pn (units) 7.0 7.1 7.0
Average Flow = 28.4 I/sec. ( 450
Table 59 ANALYTICAL DATA -SPB - PLANT
FURNACE B SCRUBBER DISCHARGE
Concentrations, mg/1 (except as noted)
Constituents Minimum Maximum Average Net Average
Suspended Solids 318 426 373 340
Total Chromium 0.09 0.09 0.09 0.09
Hexavalent Chromium -
Total Cyanide 0.87 0.87 0.87 0.87
Free Cyanide - - - -
Manganese 256 256 256 256
Oil 1.6 1.6 1.6 1.6
Iron 18.0 18.0 18.0 17.4
Zinc 4B. 48 48 48
Aluminum 13.0 13.0 13.0 12.3
Phenol 0.22 0.22 0.22 0.22
Phosphate - - - 0
Lead 5.6 5.6 5.6 5.6
pH (units) 6.4 6.9 6.7
Average Flow = 25.2 I/sec. ( 400 gpm)
95
-------
Table 60. ANALYTICAL DATA -SPC- PLANT
METALS REFINING SCRUBBER DISCHARGE
Constituent
Suspended Solids
Total Chromium
Hexavalent Chromium
Total Cyanide
Free Cyanide
Manganese
Oil
Iron
Zinc
Aluminum
Phenol
Phosphate
Lead
pH (units)
Average Flow =
Concentrations, mg/1 (except as noted)
Minimum Maximum Average Net Average
874
0.06
597
1.2
1.82
0.46
0.87
1,674 1,204
0.06 0.06
597
1.2
1.82
0.46
0.87
597
1.2
1.82
0.46
0.87
7.8 8.7 8.2
22.11/sec. ( 350gpm)
1,171
0
0
0
597
1.2
1.24
0.44
0.20
0
0
0
Table 61. ANALYTICAL DATA -SPD - PLANT E
SLAG SHOTTING WASTEWATER
Constituents
Suspended Solids
Total Chromium
Hexavalent Chromium
Total Cyanide
Free Cyanide
Manganese
Oil
Iron
Zinc
Aluminum
Phenol
Phosphate
Lead
pH (units)
Concentrations, mg/1 (except as noted)
Minimum Maximum Average Net Average
132
0.03
54
1.2
0.28
0.13
10.5
7.3
302
0.03
54
1.2
0.28
0.13
10.5
7.4
217
0.03
54
1.2
0.28
0.13
10.5
7.5
184
0
0
0
54
1.2
0
0.11
9.8
0
0
0
Average Flow =110.3 I/sec. (1,750 gpm)
96
-------
Table 62 ANALYTICAL DATA -SP E- PLANT E
FURNACE C SCRUBBER DISCHARGE
Concentrations/ mg/1 (except as noted)
Constituent Minimum Maximum Average Net Average
Suspended Solids 264 364 317 284
Total Chromium 0.57 0.57 0.57 0.41
Hexavalent Chromium -
Total Cyanide 0.16 0.16 0.16 0.16
Free Cyanide -
Manganese 21.9 21.9 21.9 21.4
Oil 1.8 1.8 1.8 1.8
Iron 3.19 3.19 3.19 2.61
Zinc 8.7 8.7 8.7 8.7
Aluminum 7.1 7.1 7.1 6.4
Phenol 0.09 0.09 0.09 0.09
Phosphate 0.32 0.32 0.32 0.32
Lead 0.26 0.26 0.26 0.26
pH (units) 7.3 7.3 7.3
Average Flow = 50.4 I/sec. ( 800 gpm)
Table 63 ANALYTICAL DATA -SPF - PLANT E
FURNACE D SCRUBBER DISCHARGE
Concentrations, mg/1 (except as noted)
Constituents Minimum Maximum Average Net Average
Suspended Solids 268 414 343 310
Total Chromium 0.10 0.10 0.10 0
Hexavalent Chromium -
Total Cyanide 0.96 0.96 0.96 0.96
Free Cyanide -
Manganese 4.22 4.22 4.22 3.73
Oil 1.6 1.6 1.6 1.6
Iron 4.00 4.00 4.00 3.42
Zinc 3.00 3.00 3.00 2.98
Aluminum 1.68 1.68 1.68 1.01
Phenol 0.15 0.15 0,15 0.15
Phosphate 0.50 0.50 0.50 0.50
Lead 1.03 1.03 1.03 1.03
pH (units) 4.4 4.4 4.4
Average Flow =50.4 I/sec. ( 800 gpm)
97
-------
Table 64. ANALYTICAL DATA -SP G- PLANT E
FURNACE 1. SCRUBBER DISCHARGE
Constituent
Concentrations, mg/1 (except as noted)
Suspended Solids
Total Chromium
Hexavalent Chromium
Total Cyanide
Free Cyanide
Manganese
Oil
Iron
Zinc
Aluminum
Phenol
Phosphate
Lead
pH (units)
Minimum
3
1
,244
0.
_
—
,576
6.
51
178
0.
-
11.
8.
50
94
09
7
6
Maximum
4,140
0.
_
—
1,576
6.
51
178
0.
-
11.
8.
50
94
09
7
7
Average Net Average
3,753
0.
_
—
1,576
6.
51
178
0.
-
11.
8.
50
94
09
7
6
3,720
0.
0
0
1,576
6.
51
177
0.
0
11.
34
36
09
7
Average Flow =44.1 I/sec. ( 700 gpm)
Table 65. ANALYTICAL DATA -SP H - PLANT E
FURNACE E SCRUBBER SETTLING BASIN DISCHARGE
Constituents
Concentrations, mg/1 (except as noted)
Suspended Solids
Total Chromium
Hexavalent Chromium
Total Cyanide
Free Cyanide
Manganese
Oil
Iron
Zinc
Aluminum
Phenol
Phosphate
Lead
pH (units)
Minimum
3,
1,
348
0
322
1
7
89
178
9
8
.17
_
—
.0
.16
—
—
.1
.5
Maximum Average
11,364
0
1,322
1
7
89
178
9
8
6
.17
_
-
1
.0
.16
-
-
.1
.6
,080
0
,322
1
7
89
178
9
8
.17
_
-
.0
.16
—
—
.1
.6
Net Average
6,047
0.
0
0
1,322
1.
6.
89
177
0
0
9.
01
0
58
1
Average Flow = 44.1 I/sec. ( 700 gpm)
98
-------
Table 66 ANALYTICAL DATA -SP I- PLANT
SLAG CONCENTRATOR WASTEV7ATER
Concentrations, mg/1 (except as noted)
Constituent Minimum Maximum Average Net Average
Suspended Solids 856 872 864 831
Total Chromium 2.04 2.04 2.04 1.88
Hexavalent Chromium o
Total Cyanide - 0.013 0.007 0.007
Free Cyanide -
Manganese 4.39 4.81 4.60 4.11
Oil 0.2 2.2 1.2 1.2
Iron 5.8 14.6 10.2 9.6
Zinc 0.22 0.22 0.22 0.20
Aluminum 10.7 10.7 10.7 10.0
Phenol - - - ' o
Phosphate o
Lead 0
pH (units) 6.1 6.2 6.2
Average Flow = 107.ll/sec. (1,700 gpm)
Table 67 ANALYTICAL DATA -SP J - PLANT
SLAG TAILINGS POND DISCHARGE
Concentrations, mg/1 (except as noted)
Constituents Minimum Maximum Average Net Average
Suspended Solids 46 90 62 29
Total Chromium 0.02 0.16 0.09 0
Hexavalent Chromium 0
Total Cyanide 0.006 0.006 0.006 0.006
Free Cyanide -
Manganese 0.95 1.26 1.08 0.59
Oil 0
Iron 1.14 1.54 1.32 0.74
Zinc 0.032 0.058 0.048 0.026
Aluminum 0.72 1.13 0.86 0.19
Phenol 0.25 0.25 0.25 0.25
Phosphate 0
Lead - - - 0
pH (units) 6.2 6.9 6.4
Average Flow =107.1 I/sec. (1,700
99
-------
Table 68 ANALYTICAL DATA -SP K- PLANT E
LAGOON #3 INFLUENT
Concentrations, mg/1 (except as noted)
Constituent
Suspended Solids
Total Cnromium
Hexavalent Cnromium
Total Cyanide
Free Cyanide
Manganese
Oil
Iron
Zinc
Aluminum
Phenol
Phosphate
Lead
pH (units)
Average Flow
Minimum Maximum Average Net Average
32
0.55
0.190
-
-
24.4
0.4
0.86
4.22
1.44
—
-
—
6.7
=447.3 I/sec
972
1.2
0.205
-
-
26.1
0.4
1.49
7.90
2.60
—
-
' 0.06
7.0
. (7,100
183
0.77
0.198
-
-
25.4
0.4
1.28
5.55
2.04
_
-
0.04
6.8
gpm)
150
0.61
0.198
0
0
24.9
0.4
0.70
5.53
1.37
0
0
0.04
Table 69 ANALYTICAL DATA -SP L - PLANT E
LAGOON #3 EFFLUENT
Concentrations, mg/1
Constituents
Suspended Solids
Total Chromium
Hexavalent Chromium
Total Cyanide
Free Cyanide
Manganese
Oil
Iron
Zinc
Aluminum
Phenol
Phosphate
Lead
pH (units)
Minimum
2
0
86
0
0
0
7
.08
—
-
-
-
.27
.22
.11
—
-
—
.0
Maximum
30
0
0
93
0
0
0
0
2
7
.08
-
.008
-
.4
.43
.46
.21
-
.73
—
.2
(except as
Average
15
0
0
91
0
0
0
0
0
7
.08
-
.005
-
.2
.35
.34
.15
-
.9
-
.2
noted)
Net Average
0
0
—
0.
0
91
0.
0
0
0
0
0.
0
005
2
9
Average Flow = 632.8l/sec. (10,045 gpm)
100
-------
Table 70. ANALYTICAL DATA -SP M- PLANT
INTAKE RIVER WATER
concentrations, mg/1 (except as noted)
Constituent
Suspended Solids
Total Chromium
Hexavalent Chromium
Total Cyanide
Free Cyanide
Manganese
Oil
Iron
Zinc
Aluminum
Phenol
Phosphate
Lead
pH (units)
Minimum
24
0.16
_
_
—
0.49
—
0.54
0.022
0.67
—
—
—
7.2
Maximum
38
0.16
_
_
—
0.49
0.2
0.62
0.022
0.67
_
-
—
7.2
Average
33
0.16
_
—
-
0.49
—
0.58
0.022
0.67
_
-
—
7.2
Net Average
_
_
_
_
-
_
_
_
—
_
_
_
Average Flow = 13,366 I/sec. ( 212,150
Table 71 ANALYTICAL DATA -SP N - PLANT E
COOLING WATER DISCHARGE
Concentrations, rag/1 (except as noted)
Constituents
Suspended Solids
Total Chromium
Hexavalent Chromium
Total Cyanide
Free Cyanide
Manganese
Oil
Iron
Zinc
Aluminum
Phenol
Phosphate
Lead
pH (units)
Minimum
90
6.6
-
-
-
0.053
—
3.42
0.045
4.28
—
1.98
—
3.8
Maximum
176
6.6
—
0.014
-
4.61
0.4
32.
0.045
4.28
—
1.98
-
7.2
Average
125
6.6
—
0.005
-
1.58
0.3
15.0
0.045
4.28
-
1.98
-
5.4
Net Average
92
6.4
0
0.005
-
1.09
0.3
14.4
0.023
3.61
0
1.98
0
Average Flow = 3,571 I/sec. ( 56,680
gpm)
101
-------
Table /^ ANALYTICAL DATA -t>F c~ ri^i*. £,
COMBINED SLAG SHOTTING & COOLING WATER DISCHARGE
Constituent
Suspended Solids
Total Chromium
nexavalent Chromium
Total Cyanide
Free Cyanide
Manganese
Oil
Iron
Zinc
Aluminum
Phenol
Phosphate
Lead
pH (units)
Average Flow =
Concentrations, mg/1 (except as noted)
Minimum Maximum Average Net Average
148
0.02
19.1
1.0
3.72
0.049
4.95
192
0.02
19.1
1.0
3.72
0.049
4.95
170
0.02
19.1
1.0
3.72
0.049
4.95
7.5 7.5 7.5
50.41/sec. ( SOOgpm)
137
0.02
0
0
18.6
1.0
3.14
0.027
4.28
0
0
0
Table 73 ANALYTICAL DATA -SP P - PLANT E
FLY ASH INFLUENT TO .LAGOON
Constituents
Suspended Solids
Total Chromium
Hexavalent Chromium
Total Cyanide
Free Cyanide
Manganese
Oil
Iron
Zinc
Aluminum
Pnenol
Phosphate
Lead
pH (units)
Concentrations, mg/1 (except as noted)
Minimum Maximum Average Net Average
1,246
20,156 7,667
7,634
6.6 7.0 6.7
Average Flow = 70.9 I/sec. (1,125 gpm)
102
-------
Table 74. ANALYTICAL DATA -SP Q- PLANT E
FLY ASH INFLUENT TO LAGOON
Constituent
Suspended Solids
Total Chromium
Hexavalent Chromium
Total Cyanide
Free Cyanide
Manganese
Oil
Iron
Zinc
Aluminum
Pnenol
Phosphate
Lead
pH (units)
Concentrations, mg/1 (except as noted)
Minimum Maximum Average Net Average
510
5,200 2,209
2,176
6.6
6.8
6.7
Average Flow =70.9 I/sec. (1,125 gpm)
Table '/b ANALYTICAL DATA -SP'A - PLANT F
INTAKE WATER
Constituents
Suspended Solids
Total Chromium
Hexavalent Chromium
Total Cyanide
Free Cyanide
Manganese
Oil
Iron
Zinc
Aluminum
Phenol
Phosphate
Lead
pH (units)
Average Flow =
Concentrations, mg/1 (except as noted)
Minimum Maximum Average Net Average
17
U.01
0.026
1.0
0.008
17
0.01
0.026
1.0
0.008
17
0.01
0.026
1.0
0.008
7.3 7.3 7.3
25.2 l/sec. ( 400 gpm)
103
-------
PLANT F
This plant utilizes seven electric arc furnaces to produce a product
line including 50% ferrosilicon, low carbon ferrochromesiiicon, high
carbon ferrochromium, low carbon ferrochromium and silicon metal. The
furnaces range in size from 10 mw to 36 mw with a collective capacity of
142 mw. No wet air pollution devices are used; baghouses have been
installed on some furnaces. The water use system is as shown in figure
13.
All plant water is supplied from wells and the furnace cooling water is
recirculated. Blowdown from all three cooling towers is automatically
controlled by total solids levels. Flow rate in the cooling tower
serving 4 furnaces with a capacity of 51 mw is 76 I/sec (1200 gpm) .
Bleed-off from this unit is 5 I/sec (80 gpm) or 6.6% of, the
recirculating flow. Another cooling tower serving a 20 mw furnace has a
flow rate of 50 I/sec (800 gpm) and a bleed-off of 1 I/sec (20 gpm) .or'
2.5% of the recirculating flow. Two additional furnaces with a capacity
of 65 mw are served by a 316 I/sec (5000 gpir.) recirculating flow and a
bleed-off of 13 I/sec (200 gpm) or H% of the flow. Water treatment in
the cooling system consists of a chromate based proprietary compound and
algaecides.
Except for the overflow from septic tanks and isolated roor drains, the
cooling system bleed-off is the major source of the plant discharge.
Yard drainage resulting from surface run-off is collected and transfered
to a small off-site lagoon. Under normal conditions there is no
discharge from the lagoon as accumulated waste water either evaporates
or drains through the lagoon bottom.
With 6 furnaces operating during the sampling period at 92.8 mw, the
cooling water use was thus 17.15 1/kwhr (4.53 gal/kwhr). A limited
number of samples were collected at this plant and the analytical data
are summarized in Tables 75 through 77. The temperature drop across the
cooling tower is 5.6°C (10°F).
A slag concentration process is used at this plant which utilizes water
on a completely closed recirculation system, the only discharge of slag
fines being to a closed lagoon, i.e., a lagoon with no outlet. This
process was not operating at the time of our visit.
10U
-------
Figure 13.
PLANT F V^ATER AND WASTE WATER SYSTEMS
SLAG CONCENTRATOR
ILAGOONJ
(No' Discharsej (No Discharge)
TO RIVER
105
-------
Table 76 ANALYTICAL DATA -SPB- PLANT F
COOLING TOWER SLOWDOWN
Constituent
Suspended Solids
Total Chromium
Hexavalent Chromium
Total Cyanide
Free Cyanide
Manganese
Oil
Iron
Zinc
Aluminum
Phenol
Phosphate
Lead
pH (units)
Average Flow =
Concentrations, mg/1
Minimum Maximum
14
10
0
0
1
0
6
5
12.
.8
.015
—
—
.093
.4
.11
.98
—
—
—
—
.9
6 I/sec
14
10.
0.
_
—
0.
1.
0.
6.
—
—
-
—
5.
. (
8
015
093
4
11
98
9
200
(except as noted)
Average
14
10
0
0
1
0
6
5
.8
.015
_
—
.093
.4
.11
.98
_
_
—
—
.9
Net
0
10
0
0
0
0
0
6
0
0
0
0
Average
.8
_
.067
,.4
.11
.97
gpm)
Table 77 ANALYTICAL DATA -SP C - PLANT F
PLANT DISCHARGE
Concentrations, mg/1 (except as noted)
Constituents
Suspended Solids
Total Chromium
Hexavalent Chromium
Total Cyanide
Free Cyanide
Manganese
Oil
Iron
Zinc
Aluminum
Phenol
Phospnate
Lead
pH (units)
Average Flow
Minimum Maximum
14
13.6
0.008
0.010
-
0.370
4.2
0.58
6.98
0.67
_
—
—
6.5
= 20.8 i/Sec
14
13.6
0.008
0.010
-
0.370
4.2
0.58
6.98
0.67
_
—
—
6.5
. ( 330
Average
14
13.6
0.008
0.010
-
0.370
4.2
0.58
6.98
0.67
_
— '
—
6.5
gpm)
Net Average
0
13.6
_
0.010
—
0.344
3.2
0.58
6.97
0.67
0
0
0
106
-------
PLANT G
This plant has two 35 mw open furnaces which produce ferrociiromium and a
slag concentration operation. At times ferrochrcmesilicon is produced
here. The water flow diagram for the plant is shown in Figure 14. Air
pollution control is by means of electrostatic precipitators which are
preceded by spray towers. The gases from the furnaces are conditioned
by the water sprays in the towers in order to improve tne perrormance of
the precipitators; ammonia is added to the spray water.
The water supply is purchased city water and originates from welis. The
cooling water used on the furnaces is ^circulated tnrough a cooling
tower at the rate of 316 I/sec (5000 qpm) . The sr^ray towers remove a
portion of the. particulates from the furnace gases prior to the
precipitators; trie resultant slurry passes through settling uasins near
the furnaces and then a lagoon which has Leer; excavated rrom a slag
pile.
The slag concentrator is a sink-float process in which slag rines are
separated from larger, usable slag particles and in turn from
recoverable metal. The products ar~ thus slaq for sale ana metal for
reuse; the waste is a slurry of slag fines. The waste stream is treated
in 2 small lagoons in series prior to discharge to a stream.
Plant production has been reported at 245 kkcis (270 short tons) of alloy
per day. Reference 32 indicates a factor of 4.2 mwhr per ton, i.e., a
furnace load of 1,134 mwhr per day. Analytical data are summarized in
Tables 78 through 83, for sampling locations designated in figure 14.
107
-------
Figure 14.
PLANT G WATER AND WASTEWATER SYSTEMS
o
00
SPRAY
TOWER
CITY
WATER
FURNACE
t
COOLING
TOWER
i
r
FURNACE
SETTLING
BASIN
SPRAY
TOWER
SETTLING
BASIN
•©-+
LAGOON
LAGOON
LAGOON
SLAG
CONCENTRATION
-------
Table 78. ANALYTICAL DATA -SP/
INTAKE CITY WATER
PLANT
Constituent
Suspended Solids
Total Chromium
Hexavalent Chromium
Total Cyanide
Free cyanide
Manganese
Oil
Iron
Zinc
Aluminum
Pnenol
Phosphate
Lead
pH (units)
Concentrations, mg/1 (except as noted)
Minimum Maximum Average Net Average
0.030
0.2
0.13
0.159
0.030
0.2
0.14
0.159
6.9
7.9
0.030
0.2
0.13
0.159
7.3
Average Flow =20.5 I/sec. ( 325 gpm)
Table 79. ANALYTICAL DATA -SPl - PLANT
COOLING TOWER SLOWDOWN
Constituents
Suspended Solids
Total Chromium
Hexavalent Chromium
Total Cyanide
Free Cyanide
Manganese
oil .
Iron
Zinc
Aluminum
Phenol
Phospnate
Lead
pH (units)
Average Flow =
Concentrations, mg/1 (except as noted)
Minimum Maximum Average Net Average
18
3.23
1.43
0.094
0.2
0.19
0.52
0.98
0.05
40
3.35
1.57
0.094
0.4
0.46
0.71
0.98
0.15
25
3.31
1.49
0.094
0.3
0.32
0.65
0.98
0.12
7.3 8.4 8.0
1.6 I/sec. ( 25 gpm)
25
3.31
1.49
0
0
0.064
0.1
0.19
0.491
0.98
0
0.12
0
109
-------
Table 80 ANALYTICAL DATA -SPC- PLANT G
SPRAY TOWER DISCHARGE
Constituent
Suspended Solids
Total Chromium
Hexavalent Chromium
Total Cyanide
Free Cyanide
Manganese
Oil
Iron
Zinc
Aluminum
Phenol
Phosphate
Lead
pH (units)
Concentrations/ mg/1 (except as noted)
Minimum
4,134
2.66
-
-
-
1.68
0.2
1.77
0.75
4.34
-
0.01
-
7.3
Maximum
6,104
8.36
0.49
-
-
14.0
0.6
3.50
5.28
23.0
-
0.02
-
8.6
Average Net Average
4,980
4.76
0.32
-
-
8.15
0.3
2.58
2.45
11.28
-
0.02
-
8.1
4,873
4.76
0.32
0
0
8.12
0.1
2.45
2.29
11.28
0
0.02
0
Average Flow = 1.1 I/sec. ( 17.5gpm)
Table B1 ANALYTICAL DATA -SPD - PLANT G
SETTLING BASIN EFFLULUT
Constituents
Suspended Solids
Total Chromium
Hexavalent Chromium
Total Cyanide
Free Cyanide
Manganese
Oil
Iron
Zinc
Aluminum
Phenol
Phosphate
Lead
pH (units)
Concentrations, mg/1 (except as noted)
Minimum Maximum Average Net Average
204 1,898
3.48 7.44
2.89
1.27
2.67
7.8
7.7
3.81
5.87
6.83
29.0
8.9
Average Flow = 3.8 I/sec. ( 60
784
5.29
3.33
0.4
2.95
4.75
21.9
0.03
8.3
gpm)
784
5.29
0
0
0
3.30
0.2
2.82
4.59
21.9
0
0.03
0
110
-------
Table £2 ANALYTICAL DATA -SPE- PLANT G
PLANT DISCHARGE
Concentrations, mg/1 (except as noted)
Constituent
Suspended Solids
Total Chromium
Hexavalent Chromium
Total Cyanide
Free Cyanide
Manganese
Oil
Iron
Zinc
Aluminum
Phenol
Phosphate
Lead
pH (units)
Average Flow
Minimum Maximum
96
2.26
_
—
—
0.«7
0.4
0.45
0.35
1.60
—
0.01
-
8.0
= 3.8 I/sec
104
2.81
_
_
—
1.45
2.0
0.83
1.15
3.49
—
0.01
-
8.2
. ( 60
Average
101
2.52
_
_
_
1.2U
1.1
0.60
0.84
2.57
_
0.04
—
8.1
qpm)
Net Average
101
2.52
0
0
0
1.17
0.9
0.47
0.68
2.57
0
0.04
0
Table B3 ANALYTICAL DATA -SPF - PLANT G
SLAG PROCESSING DISCHARGE
Concentrations, mg/1 (except as noted)
Constituents
Suspended Solids
Total Chromium
Hexavalent Chromium
Total Cyanide
Free Cyanide
Manganese
Oil
Iron
Zinc
Aluminum
Phenol
Phosphate
Lead
pH (units)
Minimum
26
0.55
0.16
-
-
0.50
0.8
0.98
0.088
0.27
—
-
—
8.4
Maximum
2,894
4.54
0.45
—
-
10.8
1.0
5.33
3.36
37.0
—
-
—
9.5
Average
1,250
2.61
0.30
—
-
4.14
1.0
4.38
1.65
14.1
—
-
—
8.9
Net Average
1,250
2.61
0.30 '
0
0
4.11
0.8
4.25
1.49
14.1
0
0
0
Average Flow = 0-66 i/sec. ( 10.4 gpm)
111
-------
PLANT H
Chromium metal is produced at this plant by an aluminothermic process
using chromium oxide produced by the exothermic reaction of wood flour
and sodium dichromate. The production of chromium oxide is not
considered here.
The off-gases from the aluminothermic process are cleaned in a unique
"wet baghouse" system shown in Figure 15. Water sprays and a wet
dynamic scrubber preceed the baghouse and an air heater which raises the
gas temperature above the dewpoint to prevent bag clogging. The bags
are cleaned by water sprays between each batch^type operation and are
dried prior to the next cycle. The waste water effluent contains
suspended solids and hexavalent chromium as the principal pollutants.
The waste water is treated batchwise in a series of ruober lined lagoons
as shown in Figure 16. There are three reduction basins which each
treat one batch of waste water from the baghouse. Treatment time as
measured from the filling of the basin to discharge of treated waste-
water to the sludge lagoon should take approximately two hours. Two
56,775 liters (15,000 gallon) tanks are provided for treatment
flexibility and storage.
Sufficient sulfuric acid addition capacity is provided to lower the
waste water pH to about 3.0. (It is at this point pH level where the
chemical reduction of the chromium is most efficient.) At maximum
conditions, the daily sulfuric acid requirements are expected to be 454
kg/day (1,000 Ibs/day).
Sulfur dioxide added to the waste water through chlorine-type
sulfonators is the reducing agent for the treatment process. The
theoretical reduction of chromium requires approximately .5 kg (1 Ib.)
of sulfur dioxide for every kg (2 Ib.) of chromates (CrO3) to be
reduced. On a daily basis, 136 kg (300 Ib.) of SO2 is required.
Upon completion of chemical reduction, sodium hydroxide is added to the
basin to raise the pH to form an insoluble chromium hydroxide from the
reduced chrome. Approximately 36 kg/day (80 Ib/day) of sodium hydroxide
is required under maximum flow conditions.
Diffused air agitation is provided to completely mix the reduction basin
and to prevent the settling of precipitated solids before the waste
water is released to the sludge lagoons. The air supply capacity was
based on providing 0.054 cu. m/hr/gal. (0.5 cu. ft./hr/gal.) of waste
water to be mixed.
The rubber-lined sludge lagoons have an approximate volume of 1,741,100
liters (460,000 gallons) when gravity flow is used from the reduction
basins to the lagoons. Pumping the treated waste water, however, could
theoretically utilize the full 3.5 m (11 ft.) depth of the lagoon and
112
-------
would almost triple their capacity. Currently, gravity flow is used,
but provisions have been made for the later addition or pumps if needed.
Sludge production is expected to approach U5U kg/day (1,000 lb/ day) .
Approximately six months of sludge storage is provided cefore removal
would be required. This storage capacity will allow for 180 days of
continuous operation at the maximum flew and chromium concentrations.
Analytical data from the plant survey are summarized in Tables 8U
through 91 for sampling points indicated in Figure 16. The measured
temperature rise of the cooling water was 6°C (10.0°F). The cooling
pond is designed for a maximum rise of 2.78°C (5°F), and is 61 m X 67 m
(200 ft. X 220 ft.).
113
-------
Figure 151
DIAGRAM OF*WET BAGHOUSE* SYSTEM
FIRING CUBICLE
WITH
FIRING POT
DUCTS WITH
WATER SPRAYS
BAGS CLEANED BY
INTERNAL WATER SPRAY
TRAP
MAIN EXHAUST FAN
SLURRY TO
DRAIN
(CLEANED GAS TO ATMOSPHERE)
-------
Figurf- 16.
PLANT H WATER AND WASTEWATER SYSTEMS
GASES
EXOTHERMIC
SMELTING
OPERATION
t
i
BAGHOUSE
«-
CITY
WATER
TREATMENT
(LINED)
SEASONAL BY-PASS
•
TO STREAM
-^
»
i
THtRMAL
POND
(UNLINED)
i
*
t
^
SETTLING
LAGOON
(LINED)
POLISHING
LAGOON
(LINED)
COOLING
WAI EK
-------
Table 84 ANALYTICAL DATA -SP*- PLANT
INTAKE CITY WATER
Constituent
Suspended Solids
Total Chromium
Hexavalent Chromium
Total Cyanide
Free Cyanide
Manganese
Oil
Iron
zinc
Aluminum
Phenol
Phosphate
Lead
pH (units)
Average Flow =
Concentrations, mg/1 (except as noted)
Minimum Maximum Average Net Average
0.026
0.22
0.016
0.026
0.29
0.016
5.6 5.7
28.4 I/sec. ( 450
0.026
0.25
0.016
5.6
Table 35 ANALYTICAL DATA -SPB - PLANT
BAGHOUSE WASTEWATER DISCHARGE
Constituents
Suspended Solids
Total Chromium
Hexavalent Chromium
Total Cyanide
Free Cyanide
Manganese
Oil
Iron
Zinc
Aluminum
Phenol
Phosphate
Lead
pH (units)
Concentrations/ mg/1 (except as noted)
Minimum Maximum Average Net Average
106
101
17
0.040
1.2
0.04
0.002
220
121
44
O.U51
2.b
0.04
0.003
136
112
37
0.048
1.8
0.04
0.002
136
112
37
0
0
0.022
1.8
0
0
0
0
0
0
12.3
12.4
12.3
116
-------
Table ot ANALYTICAL DATA -SPC - PLANT
TREATED BAGHOUSE WASTEWATER
Concentrations, mg/1 (except as noted)
Constituent Minimum Maximum Average Net Average
Suspended Solids 674 748 713 713
Total Chromium 114 114 114 114
Hexavalent Chromium 0.047 0.363 0.162 0.162
Total Cyanide o
Free Cyanide o
Manganese 0.41 0.73 0.54 0.51
Oil 0.8 2.0 1.3 1.3
Iron 2.64 3.73 3.27 3.01
Zinc 0.90 1.53 1.27 1.25
Aluminum 127 130 129 129
Phenol - - - 0
Phosphate 0.41 0.50 0.46 0.46
Lead - - - 0
pH (units) 4.7 6.2 5.4
Average Flow = 100,303 I/da (26,500 gal/da)
Table b7 ANALYTICAL DATA -SFD - PLANT H
SETTLING LAGOON DISCHARGE
Concentrations/ mg/1 (except as noted)
Constituents Minimum Maximum Average Net Average
Suspended Solids 58 70 66 66
Total chromium 17.9 18.3 18.1 18.1
Hexavalent chromium 0.189 0.218 0.208 0.208
Total Cyanide - - - 0
Free Cyanide 0
Manganese 0.70 0.70 0.70 0.67
Oil 3.4 3.4 3.4 3.4
Iron 0.24 0.42 0.32 0.06
Zinc 0.77 0.77 0.77 0.75
Aluminum 31 31 31 31
Phenol 0
Pnosphate 0.05 0.05 0.05 0.05
Lead 0
pH (units) 4.9 4.9 4.9
Average Flow = i/sec. ( gpm)
J.17
-------
Table 08 ANALYTICAL DATA -SPE- PLANT
POLISHING LAGOON DISCHARGE
Concentrations, mg/1 (except as noted)
Constituent
Suspended Solids
Total Chromium
Hexavalent Chromium
Total Cyanide
Free Cyanide
Manganese
Oil
Iron
Zinc
Aluminum
Phenol
Phosphate
Lead
pH (units)
Average Flow
Minimum Maximum
3b
7.13
0.214
_
-
0.92
4.0
0.17
0.44
15.3
_
0.05
—
5.2
= 0.32 I/sec
56
7.56
0.261
_
—
0.92
4.0
0.17
0.44
15.3
—
0.05
_
5.2
. ( 5
Average
47
7.40
0.245
_
—
0.92
4.0
0.17
0.44
15.3
_
0.05
_
5.2
gpm)
Net Average
47
7.40
0.245
0
0
0.89
4.0
0
0.42
15.3
0
0.05
0
Table SrJ ANALYTICAL DATA -SPF - PLANT
PLANT DISCHARGE
Concentrations, mg/1 (except as noted)
Constituents
Suspended Solids
Total Chromium
Hexavaient Chromium
Total Cyanide
Free Cyanide
Manganese
Oil
Iron
Zinc
Aluminum
Phenol
Phosphate
Lead
pH (units;
Average Flow
Minimum Maximum
_
0.37
0.024
-
-
0.22
2.0
0.27
0.023
_
—
0.05
-
5.2
= 18. 9 I/sec
22
0.81
0.090
0.016
0.016
0.40
4.0
0.34
0.074
—
—
0.05
-
6.1
. ( 300
Average
6
0.57
0.057
0.009
0.009
0.32
2.7
0.29
0.048
—
_
0.05
—
5.7
gpm)
Net Average
6
0.57
0.057
0.009
0.009
0.29
1.8
0
0.032
0
0
0.04
0
118
-------
Table 90 ANALYTICAL DATA -SPG- PLANT H
PLANT WELL WATER
Constituent
Suspended Solids
Total Chromium
Hexavalent Chromium
Total Cyanide
Free Cyanide
Manganese
Oil
Iron
Zinc
Aluminum
Phenol
Phosphate
Lead
pH (units)
Average Flow =
Concentrations, mg/1 (except as noted)
Minimum Maximum Average Net Average
0.037
4.6
0.52
0.011
0.037
4.6
0.57
0.011
0.037
4.6
0.55
0.011
0.05 0.05 0.05
5.2 5.3 5.3
3.01 i/sec. ( 48 gpm)
Taole 91 ANALYTICAL DATA -SPH - PLANT H
COOLING WATER
Constituents
Suspended Solids
Total Chromium
Hexavalent Chromium
Total Cyanide
Free Cyanide
Manganese
Oil
iron
Zinc
Aluminum
Phenol
Phosphate
Lead
pH (units)
Average Flow =
Concentrations, mg/1 (except as notea)
Minimum Maximum Average Net Average
40
0.44
0.38
1.45
2.2
1.49
0.060
0.27
40
0.44
0.38
1.45
2.2
1.49
0.060
0.27
40
0.44
0.38
1.45
2.2
1.49
0.060
0.27
6.0 6.0 6.0
18.6 I/sec. ( 295 gpm)
40
0.44
0.38
0
0
1.42
2.2
1.24
0.044
0.27
0-
0
0
119
-------
In Figure 17, a waste treatment scheme is shown in wnich all of the
waste constituents for which guidelines have been developed in
Categories I and II can be reduced to minimal concentrations. Not all
waste streams will contain all constituents and appropriate
modifications of this general scheme can be made to reduce costs.
The first step consists of raising the pH of the waste stream to about
11 and the addition of sufficient chlorine to maintain a free residual,
followed by sedimentation. In this step, phenol is oxidized, cyanide is
oxidized to cyanate, and the phosphates and manganese are precipitated.
In the second step, additional chlorine is added and tne pri is lowered
to 7.0 by a suitable acid. With a reaction time of 60 minutes, the
cyanate is oxidized to CO2 and N2_. In the third step, the pH is lowered
to 2.5 and sulfur dioxide is added. Allowing a reaction time of 30
minutes, the hexavalent chromium is reduced -o trivaient. The fourth
step consists of raising the pH to 8.2, adding a polyelectrolyte, and
allowing sedimentation. At this point, the trivaient chromium will be
removed and final clarification accomplished. With a sufficiently low
overflow rate and addition of flocculants in sufficient quantities, an
effluent solids concentration of 25 mg/1 of suspended solids can be
attained and metals reduced to low levels.
Sand filtration of the final clarifier effluent, with backwash returned
to the clarifier, can reduce suspended solids concentrations to 15 mg/1
or less. After filtration, the water . may be recycled back to the
scrubbers.
For a waste stream containing no phenol or cyanide, but witn hexavalent
chromium, a single initial clarifier operated at a pH of 10 and with
polyelectrolyte addition should reduce phosphate ana metals to low
concentrations and no chlorination is necessary. In this case, the
first two steps of Figure 17 are combined into one, and the remainder of
the process steps are as shown.
For a waste stream containing no hexavalent chromium, £>ut with phenol
and cyanide, the chromium reduction step is eliminated.
120
-------
Figure 17. Diagram of Waste Water Treatment System
^ PHENOL
60 MIN.
RETENTION
@ J?H 11.
60 MIN.
RETENTION
@ pH 7.
UNDERFLOW
45 MIN.
RETENTION
@ pH 2.5
UNDERFLOW
Mn,Fe,
Pb,P04
FILTER BACKWASH
Al,Zn
CLARIFIER
EFFLUENT
I
FILTER
EFFLUENT
I
*_
SAND
FILTERS
COAG
AID
^ v
L.
(
Ci
7
S(
OR
CAUS-
TIC
SLUDGE
DEWATERING
0.5 GPM/FT2
RISE RA.TE
@ pH 8.2
NEUTRALIZATION
TANK
UNDERFLOW
SLUDGE
DISPOSAL
OR
METAL
RECOVFRY
-------
The treatment scheme shown is based upon those at Plant B (alkaline
chlorination), Plant D (alkaline precipitation of metals, ana use of
sand filters), and Plant H (reduction of hexavalent chromium) . The high
hexavalent chromium levels found at Plant K may have occurred Because of
the aeration system, which may have oxidized some of the trivalent
chromium back to the hexavalent state. Additionally, tne pH after
reduction of hexavalent chromium should be raised to over 8, rather than
around 5 to 6, so that more chrome would be precipitated. it is felt
that the treatment system at Plant D, although the most sophisticated
and producing the best overall effluent of any plant in the survey, was
not operating in an optimum manner, as evidenced by the high
concentrations of suspended solids after the clarifier (112 mg/1) and
after sand filtration (38 mg/1). These concentrations are much higher
than would be expected and may have been caused by non-quiescent flow
into the clarifier and insufficient backwashing of the sand filters.
Other treatment and control methods, as presently used in tne industry,
do not produce reasonably good effluent qualities.
For example. Plant C used potassium permanganate for the oxidation of
cyanide. Cyanide was only reduced to 3.33 mg/1 in tne thickener
underflow, compared to 4.08 mg/1 in the raw waste. KMnO4 should be at
least as good an oxidizing agent as chlorine, and yet little cyanide was
oxidized at this plant. Higher dosages may have induced more oxidation,
but the cost of chlorine is less than that of permanganate, and for that
reason chlorination was selected as one of the steps in tne suggested
treatment scheme. Although the cyanide destruction system was fairly
ineffective, this plant stood out in the recirculation and reuse of
water from scrubbers and cooling, some of the blowdown from the cooling
tower was used as makeup water for the scrubber system, and 97ft of the
scrubber water was recirculated, the only blowdown being the clarifier
underflow.
Plant E used a large lagoon (70* acres) for sedimentation, and fly ash
from a captive power plant was added to this lagoon. This may explain
the low values for suspended solids obtained in the lagoon effluent
(from 2 to 30 mg/1), while other plants, such as Plant B, had suspended
solids levels of 83 mg/1 in the lagoon effluent. A lagoon may be an
alternative to clarifier-flocculators, but land may not be available at
all locations.
The control and treatment technologies which have been identified herein
are identified as applicable to the various industry categories in Table
92.
122
-------
Table 92. CONTROL AND TREATMENT TECHNOLOGIES t»Y CATEGORY
Treatment
Category. Technology
I 1
2
3
II
III
IV
1
2
1
2
1
Description
Chemical treatment, clarifier-floccuiators,
recirculation at. the scrubber
Chemical treatment, clarifier-floccuiators,
sand filters and process water recirculation
Dry dust collectors for air pollution control
Chemical treatment, ciarifier-floccuiators
Chemical treatment, clarifier-fIcccuiators,
sand filters and process water recirculation
Clarifier-floccuiators, chemical
treatment (if necessary)
Total process water recirculaticn
Once-through water use, cooling ponds,
or alternate treatment for control
of thermal pollution
(Chemical treatment of blowdown, ir presently
recirculating ccoiing water)
Cooling towers, recirculation, chemical
treatment of blowdown
It should be noted that with thf. exception of tne slag processing
operations, the raw waste loads and final effluent loads have been
calculated in terms of mwhr as the production basis. Ihis was aone for
the following reasons, after examining the other possible oasis (kg
(tons) ) :
1. Uncontrolled emission factors (upon which the raw waste loads
depend), are more uniform over the various types or products when
expressed as kg (lb)/mwhr, rather than as kg/kkg (Ib/ton).
2. Power usage is already such a large factor in production costs (about
30*) that an increase in power consumption so that tne permissible
effluent discharge would be higher is very unlikely.
3. Power usage is very well monitored at the
with a continuous automatic recording device.
furnace itselr, usually
123
-------
4. Furnaces are commonly referred to in the industry as MO mw1 or '35
mw1, rather than '50 ton' or '150 ton1, as is common practice in the
steel industry.
5. The tonnage which may be produced for a given power consumption is
fairly wide (factor of 10) and depends on the product, and numerous
products can be produced in a given furnace. Use of Kg/kKg (Ib/ton) as
limitations would involve the permit writer ir. writing a permit with
many different conditions. The reader may refer to Table 18 for
comparisons of power usage per ten for various products.
Aggregate raw waste loads, representing for some parameters such as
chromium and manganese the maximum lead which might be expected in the
waste, are shown in Tables 93 through 96. The manganese concentrations,
for example, would probably only be encourterea at these levels from a
furnace producing manganese products.
The loads were calculated from flows and concentrations as follows:
load (kg (Ib) /mwhr) = mass flow rate (kg(lb)/hr) x concentration t (106 x
furnace power (mw) )
load (kg/kkg(Ib/ton)) = mass flow rate (kq(ib)/hr) x concentration T
(amount processed (kkg (tons)/hr) x 106)
The heat load is calculated by the tcrn-ula q = me (dt) t- i-, where q is
the- heat load per mwhr, m is the maps flow rate (kg(li»)/hr, c is the
constant pressure heat capacity (kg-cal/kg°C(BTU/lb°F), dt is the
temperature difference (°C(°F)) between the ccoling water discharge and
the receiving stream, and P is the furnace power consumption (mw).
Furnace power may be calculated by dividing the number oi megawatt-hours
used in the furnace in a 24 hour period by 24 hours.
Tables 93-96, describing raw waste and treated effluent loads, have been
constructed on the following bases:
Category I - Open Electric Furnaces with Wet Air Pollution Control
Devices.
Raw Waste Load - Flow based upon the total water flow in the scrubber
[113.6 I/sec (1800 gpm) ] rather than effluent water flow at Plant E,
sample point G from the scrubber [44.2 I/sec (700 gpm) J. Concentrations
of suspended solids and manganese at that sample point adjusted
accordingly to compensate for increased flow. Phosphate and oil loads
taken from Plant D, Sample point C, and concentrations adjusted
accordingly. Chromium concentrations taken from Plant G, sample point
C.
124
-------
Treatment Level 1 - Concentrations shown are those achievable by the
treament system as shown in Figure 17, less th-s sand filter and
recirculation portions and are generally somewhat higher than those at
Plant D, sample point E. Loads are based upon concentrations shown and
a water use of 6382 1/mwhr (1686 gal/mwnr) .
Treatment Level 2 - Concentrations based on entire treatment system as
shown in Figure 17, including the sand filter and recirculation, and are
generally somewhat higher than those at Plant D, sample point E. These
levels would require better operation of the treatment system than was
necessary in Level 1. Loads based upon blewdown rate of 7ti3 1/mwhr (207
gal/mwhr) .
Treatment Level 3 - Based upon use of a dry GUST collection system for
air pollution control, which results ir no discharge of waterborne
pollutants to navigable streams. This type of dust collection equipment
is much more widely used than wet scrubbers: on this type of rurnace.
Category II - Covered Electric Furnaces and Other Smelting Operations
with Wet Air Pollution Control Devices.
Raw Waste Load - Concentrations and loads as at Plant b, sample point B,
except that chromium concentrations are taken from Plant G, sample point
C, and manganese concentrations taken from Plant C, sample jjoint C.
Loads calculated from Plant B, sample point E, flow.
Treatment Level 1 - Concentrations same as for Category I, treatment
level 1, with the exception that cyanide concentration is based upon
that found at Plant B, sample point D. Loads in kg (ii>)/mwhr were
calculated using the flows found at Plant 5, sample point D.
Treatment Level 2 - Concentrations same- as tor Category I, treatment
level 2, with cyanide concentration based or Plant P, sample point D.
Loads in kg (Ib)/mwhr based on 10t>C 1 (260 gal)/mwhr being blown down
from the recirculation system.
Note: Loads for exothermic and other nonelectric furnace smelting
operations based on water usage three times higher (per ton) tnan for
electric furnaces (per mwhr)
Category III - Slag Processing
Raw Waste Load - Maximum of Plant E, sample point I, or sample point D.
Treatment Level 1 - Eased on use of clarifier-flocculators.
Treatment Level 2 - Eased on recirculation of all water after
precipitation of fine suspended solids in clarifier-flocculators.
Category IV
125
-------
Raw Waste Load - Concentrations based upon once-througn water usage as
at Plant B, sample point E. Flow and heat load based upon average water
flow and measured temperatures at plants visited. However, it should be
recognized that any time water is recirculated through a cooling tower,
concentrations will be increased by evaporation, and -chat chromates or
phosphates will be added to the water for corrosion control. For
comparative purposes, the maximum concentrations which were found for
the primary pollutants at any plant are shown below.
Once-through
cooling Water
(mg/1)
Suspended Solids 11.0
Total Chromium 0
Hexavalent Chromium 0
Phosphate 0.22
Slowdown trom
Pecirculation System
(mg/1)
183.
13.6
1.49
2.42
Treatment Level 1 - Concentrations and heat load based upon once-through
cooling water use, with application of cooling ponds to limit
temperature rise to 2.78°C (5°F) above that of ambient water (or intake
water, if from a surface body). For those plants presently
recirculating cooling water, limits achievable by chemical treatment of
blowdown.
Treatment Level 2 - Heat load based upon a blowdown rate of 5& of
recirculation rate in a cooling tower, with a temperature rise of 2.78°C
(5°F) above that of ambient water (or intake water, if from a surface
body). Other limits achievable by treatment of blowdown.
The 24-hour maximums are generally twice the 30 day averages and based
upon maximum concentrations found at exemplary plants, or those which
might be attained during system upsets or the like. In tne case of oil
and phenol, and phosphate in Category IV, Level 1, the limitations are
1.5 times the 30 day average, and for hexavalent chromium, they are
three times the 30 day average.
STARTUP AND SHUTDOWN PROBLEMS
There have been no problems of consequence identified an connection with
the startup or shutdown of production facilities insofar as waste water
control and treatment is concerned. Cooling water, tor example, is
usually allowed to flow or recirculate during short-term production
stoppages, and as often as not, scrubber water continues to flow during
such periods. There might be some upsets in undersized lagoons or
clarifiers used in once-through systems if the water flow is abruptly
started after a shutdown. Proper operating procedures can easily handle
such occurences and there would be little or no effect in sufficiently
large facilities.
126
-------
Loss of power can effect, most of the treatment, sysrems such as chemicals
addition for flocculation, cyanide destruction, or chromium reauction-
precipitation. In such cases, however, the production process also will
stop and little effect on waste water treatment would result.
127
-------
Table 93 INDUSTRY CATEGORY I
OPEN FURNACE WITH WET AIR POLLUTION CONTROLS
CO
Raw Waste Load 30
Constituents
Suspended Solids
Total Chrcr.ium
Kexavalent
Chron-.ium
Mansanese
Oil
Phenol
Phosphate
Flow
pH
ks/'nwhr
24.0
.078
.005
10.07 .
.011
.010
gal/awhr
4335
lb/r.whr
52.8
.172
.012
22.17
.'025
.'023
Value
7.2
!r,s/l kg/mwhr
1460 .160
4.76 .0032
.32 .0002
613 .032
.7 .045
.0032
.635 .0064
1/tnwhr
16,410
Level 1 Effluent Level 2 Effluent
Day Average 24 hr Maximum 30 ^Day Average . 24 hr X.nxinun
Ib/mwhr
.352
.007
..0004
. .070
.098
.'.007
.0141
gal/mwhr
1686
ma/1 kg/mvhr Ib/aiwhr
25.0
0.5
0.03
5.0
7.0
. 5
1.0
Value
6.0-9.0
.319
.006
.0006
.064
.064
.004
.013
.703
.014
.0014
.141
.141
.010
.028
1 /rawhr
6382
rag/1 kg/mwhr
50 .012
1 .0004
.1 .00001
10 .0039
10 .0055
.7 .0002
2.0 .0001
lb/-vhr
.026
. 0009
.00002
.0086
.012
.0003
.0002
gal/mx-rlir
207
r.t- / 1 k
15.0
0.5
0.01
5.0
7.0
0.2
0.1
Value
6.0-9.
024
0008
00002
DOS
008
0003
0002
0
o/'rv.'hr
.052
.0017
.00004
.017
.017
.0007
.0003
1/ir.whr
783
r.c/1
30
1.0
.02
10
10
.4
.2
-------
Table 94 INDUSTRY CATEGORY II
COVERED ELECTRIC FURNACES AND OTHER SMELTING OPERATIONS
WITH KET AIR POLLUTION CONTROL DEVICES
Suspended Solids
Total Chromium
t-'oxavaler.t
O.ro-iura
Total Cvanide
M.?.r.".~.r>ese
Oil
Phenol
Phusphase
K)
V£>
Flow
PH
kp,
13
0
0
0
3
0
0
0.
i~-
Ra
/r."hr
.02
.040
.003
.021
.74
.033
.061
009
1/rawhr
w Waste
Ib/~-,:hr
25.57
O.OS3
0.006
0.046
8.24
0.033
0'.134
0.020
Lead
r.g/1
1555
4.
0.
2.
447
4.
7,
1.
30
kg/r.whr
76
32
49
5
27
11
1
0.
0.
0.
0.
0.
0.
0.
0.
209
004
0003
002
042
059
004
008
1/rawhr
2210
6
Value
.0-9.0
8365
Level 1 Effluent
Day Average
Ib/rwhr
.461
0.009
0.0006
0.005
0.092
0.129
O.C09
0.01S
gal/rawnr
2210
!«R
25
0
0
0
1
7
0
1
/I
.5
.03
.25
.0
.0
. 5
.0
Value
6.0-9.0
24 hr Mr.xitnura
kf./nivhr lb/~wlir r.^/1
0.419
O.OOS
0.0003
0.004
0.034
0.034
0 . 005
0.017
0
0
0
0
0
0
0
1/TBW
8365
.922
.018
.0018
.009
.184
.184
.013
.037
hr
50
1.0
0.1
0.5
10
10
0.7
2.0
k
0
0
0
0
0
0
0
c
30
S/^-hr
.0.16
.0005
.00001
.0003
.005
.007
.COO 2
.0001
Level 2
Dny Average
Effluent:
4 hr M^x-i
iTiUTt!
Ib/pvhr ir.p./l ku/^vhr ib/V.vhr -,s>/l
0
0
0
0
0
0
0
0
p.
.035
.0012
.00002
. 0006
.012
.016
.0005
.0002
al/rawlir •
280
15
0.5
0.01
0.25
5
7.0
0.2
0.1
Value
6.0-9.
0.032
0.001
0.00002
0.0005
o.on
o.o;i
0.0004
0.0002
0
0.071
0.002
0.00005
0.001
().•'! 2 3
0.023
o.cooa
C.0005
I/r-hr
1060
3:i
1.0
0.02
0.5
10
:o
0.4
0.2
-------
Table 95 INDUSTRY CATEGORY III
SLAG PROCESSING
Ul
o
Raw Waste Load
Susaended Solids
Total Chromium
Manganese
Oil
Flow
pH
kg/kkg
processed
46.0
.10'9
2.87
.064
Ib/ton
processed mg/1
91.9 864
.217 2.04
5.74 54
.128 1.2
al/ton 1/kkg
Level 1. Effluent
30 Day Average 24 hr Maximum
kg/kkg
processed
1.330
0.026
0.266
0.372
12,750 53,100
Value
6.2
Ib/ton
processed fflg/1
2.659 25
0.053 .5
0.532 5
0.745 7
gal/ton 1/kkg
12,750 53,100
Value
6.0-9.0
kg/kkg
processed
2.659
0.053
0.532
0.532
gal/ton
12,750
6
Ib/ton
processed is
5.319
.106
1.054
1.064
1/kkg
53,100
Value
.0-9.0
B/l
50
1
10
10
-------
Table 96 INDUSTRY CATEGORY IV
NONCONTACT COOLISG WATER
Raw Waste Load
Cc-.-.stituer.ts
Suspended Solids
Total Chroniun
Hcxavalcnt
Chror.iu"
Oil
Phosphate
Heat Content
Flow
?H
kn/r.-.chr Ib/awlir ir,g/l
1.590 1.30
0.0005 0.001
0.0005 0.001
0.038 0.083
0.012 0.026
kg-cal/mw'nr
408,000
.al/^-'hr
14,185
Value
7.0
11.0
.01
.01
0.7
0.22
ETU/nwhr
1,621,000
1/rwhr
53,690
Level 1 Effluent
30 Day Average 24 hr Maxiir.ua
kg/ir.whr Ib/mwhr' 'T.~/l kp/rr.v.-hr lb/rawiir ng/1
1.343 2.95.9
0.027 0.059
0.002 0.00.4
0.376 0.828
0.161 '0.355
ks-cal/nwhr
149,000
gal/raw
14,185
25.0 2.686 5.917 50
0.5 0.054 0.118 1.0
0.03 0.005 0.012 0.1
7.C 0.537 1.183 10
3.0 0.269 0.592 5.0
BXU/ssvhr ks-cal/ir.vhr BTU/rawhr
592,000 298,000 1,184,000
hr 1/rawhr
53,690
Value
6.0-9.0
Level 2 Effluent
30 Day Average 24 hr Hnxiriun
k{;/swhr Ib/r.-.-.chr ras/l ky/p-.v.'hr
0.067 O.J4S 25 0.134
0.001 0.003 0,5 0.003
0.00003 0.00006 0.01 0.00005
0.019 0.041 7.0 C.027
0.004 0.009 1.5 O.OOS
ks-cal/ir.whr 3TU/rawhr kg-cal/ro
7,500 ' 30,000 14,900
gal/nwhr
710
Value
6.0-9.0
lb.'nr.,-:;r ms/1
0.296 50
0.006 1.0
0.0001 °-02
0.059 10.0
0.013 3.0
;v-hr BTU/Ewhr
59.000
1/nwhr
2,685
-------
SECTION VIII
COST, ENERGY AND NCNWATER CH'AI.ITY ASPECT
Capital and operating cost information was obtained from each plant.
surveyed. The capital costs (per mvv capacity) for water treatment
systems at the plants surveyed varied from $^528 (for a cooling water
system, including coolinq towers, etc.) to $27,507 (for a scrubber and
cooling water treatment and recirculation system). Operating costs
varied from a low of $0.021/rnwhr (for spray tower waste water treatment.
and cooling tower operation), to a high cf ^0.770 (lor scruboer and
cooling water treatment and recircuiation).
Capital costs are given in terms or ir&tailed capacity and operating
costs in terms of units of production =ind alt-o in terms or waste water
flows. These costs were based upon cost or capital at. an interest rate
of 8 percent, and a depreciation period or lr> years.
Capital costs have been adjusted to August, 1971 dollars using tne
Chemical Engineering Plart. Cost Index (iS57-SS=100) . Tnis index has
been indicated by a consultant to ri I:*-. Ferroalloys Association to ue best
indicative of cost changes in the ir.austry. Operating costs nave been
adjusted when necessary on the basis'-; cf ar. average of j.5 percent per
year.
Lagoon costs were taken from Reference 31. Power costs Were calculated
on the basis of flow rates and pumping head, and have ueeu assumed at
one cent per kwhr, which is the cost used ir. the EPA-TFA Air Pollution
Study (Ref. 32) . This estimate hat ceen ccr.firmed by Ihe Ferroalloys
Association as being equal to the ov-ragv cost in the industry.
The following bases were used rcr cost calculations oy Category and
Treatment Level:
Category I, Treatment Level 1.
Costs were developed for the treatment system as snown in ngure 17, on
the basis of a 63.1 I/sec (1000 gem) flow rate. At a water use of 6362
1/mwhr [1686 gal/mwhr], this is equivalent, to the flow rate from a
furnace operating at 35 mw. The costs include mecnanicai equipment,
tanks, piping, valves, electrical, engineering, installation, etc. They
are based upon the complete system less the sand filter and
recirculation and may, therefore, be somewhat high, since a ^articular
plant may not require all the treatment steps. The investment costs
will probably be less (per mw) for a plant larger tnan the model, and
greater for a plant smaller than the model. Unless a giant's product
line and furnace types justified it, it would probably be more
economical to install one treatment system for the entire plant.
133
-------
Operating and maintenance costs at this level of estimation are best
figured as a percentage of capital costs for similar type plants. The
"Inorganic Chemicals Industry Profile" indicated for 59 plants" surveyed
operating costs per annual unit of production equal to 28* of the
capital cost per annual unit of production. The operating costs at
Plant C are equal to 23.4% per year of the capital cost. The operating
costs at Plant D are equal to 23.0% of the capital cost. The operating
costs at Plant B are equal to 30.9# per year of tne capital costs.
Operating costs are thus estimated on the basis of 30% per year of the
estimated capital cost, prorated as at Plant C.
Category I, Treatment Level 2.
Costs expanded from Level 1, above, to include costs oi recirculation
and sand filter, with a proportionate increase in annual ana operating
costs.
Category I, Treatment Level 3.
No direct comparison to waste water treatment and control costs can be
made. However, investment and annual costs for scrubber systems vs
those for fabric filter systems (all on 30 n?w furnaces) have been made
for four products: Std. (High Carbon (HC)) ferromanganese;
silicomanganese, HC ferrochromium and 50% ferrosilicon (Ref. 32). The
costs for scrubber systems include some water treatment - a slurry
settler and two filters for slurry dewatering. These costs are shown in
Table 99. Although the investment costs for a fabric filter system are
the same as, or only slightly lower than those for a scrubber system,
annual costs are about half. This differential in favor of the 'dry1
systems could be expected to increase markedly if any advanced waste
water treatment were utilized. Additionally, because of the lower
pressure drops required, less power is required for the operation of the
fabric filter system.
Category II, Treatment Level 1.
Costs were developed as for Category I, Level 1. 63.1 I/sec (1000 gpm)
at a use comparable to that at Plant E, sample point B, (8365 1/mwhr
[2210 gal/mwhr]), is equivalent to the flow from a furnace operating at
27 mw. As before, the investment cost per mw will be somewhat higher
for small plants and less for large plants.
Category II, Treatment Level 2 and 3.
Same as for Category I, Level 2, but based on 27 mw furnace.
Category III, Treatment Level 1.
13(f
-------
Costs were calculated for two clarifier f loccula tor s, wica the necessary
piping and pumps and other appurtenances. costs were based upon the use
of 53,148 1/kkg (12,750 gal/ton) processed.
Category III, Treatmenr Level 2.
Costs are greater than for Level I by the addition of pumps ana pipes
necessary for recycle.
Category IV, Treatment Level 1.
Costs for a cooling pond calculated at 315.5 I/sec (5,000 gpm) and 2.2°C
approach to equilibrium temperature.
Category IV, Treatment Level 2.
Costs were taken at the average for Plant A arid Plant C cooling systems.
Added to this was an estimate for the cost of reducing tne hexavalent
chromium which may be present. (phosphate removal is less costly) .
The costs for each are summarized in Tol'.lrrs 97 and 98.
135
-------
Table 97. TREATMENT LEVEL COSTS ON UNIT OF PRODUCTION BASIS
(costs on basis of mw and mwhr.unless noted thus*)
u>
Annual Costs ($
Industry Category
and Treatment Level
Category I:
Treatment Level 1
Treatment Level 2
Category II:
Treatment Level 1
Treatment Level. 2
Category III:
Treatment Level 1
Treatment Level 2
Category IV:
Treatment Level 1
Treatment Level 2
Investment
($ per mw or
17,143
21,063
22,222
27,303
2,526*
2,604*
1,266
8,444
tpd) Capital
0.103
0.127
0.134
0.165
0.344*
0.357*
0.007
0.049
per mwhr or ton)
Operating Cost
Depreciation less Power Power Total
OU38
0.169
0.178
0.219
0.459*
0.485*
0.010
0.065
0.606
0.745
0.785
0.965
0.421*
0.421*
0.0
0.354
0.(M2 0.859
U.O.L5 1.056
0.016 1.113
0.019 1.368
0.051* 1.28*
0.051* 1.31*
0.0 0.0.17
0.044 0.512
-------
Table 98 . TREATMENT LEVEL COSTS ON WASTEWATER FLOW BASIS
U)
Annual
Industry
Category
and Treatment Level
Category
Treatment
Treatment
Category
Treatment
Treatment
Category
Treatment
Treatment
Category
Treatment
Treatment
I:
Level
Level
II:
Level
Level
III:
Level
Level
IV:
Level
Level
1
2
1
2
1
2
1
2
Investment
($ per gpm)
600
737
600
737
285.29
294.12
16.54
119
Costs ($ per 1,000 gal.)
Operating Cost
Capital
0
0
0
0
o
0
0
0
.057
.070
.057
.070
.027
.028.
.0016
.013
Depreciation
0.
0.
0.
0.
0.
0.
0.
0.
076
094
076
094
036
038
0021
017
less Power
0
0
0
0
o
0
0
0
.336
.413
.336
.413
.033
.033
.240
Power
0.007
0.008
O.OG7
0. 006
0 I ' ' «i
0.004
0
0.011
Total
0.476
0.585
0.476
C.J35
100
0.103
0.004
0.281
-------
Table 99 .
SCRUBBER COSTS vs. FABRIC FILTER COSTS
FOR AIR POLLUTION CONTROL
ON 30 mw OPEN ELECTRIC SUBMERGED-ARC FURNACES
SCRUBBER SYSTEM
ui
00
HC Ferromanganese
S ilicotnariganese
HC'' Ferrochromium
50% Ferrosilicon
HC Ferromang'anese
Silicomanganese
HC Ferrochromium
50% Ferrosilicon
Investment
$
1,640,000
1,640-, COO
1,472,000
3,180,000
<$ / p .. .T
V / -U.vv
54,667
54,667
49,067
106,000
FABRIC FILTER
Investment
$
1,640,000
1,640,000
1,190,000
2,340,000
S/isw
54,667
54,667
39,667
78,000
Annual
$
826,000
8 2 6, COO
699,000
1,986,000
SYSTEM ,
A-.r.v.?.l
$
445,000
445,000
335,000
734,000
Costs
'• /
* / • '. . i : •_
3.49
4.29
2.83
?. r*
Costs
£/--•:-.:•
1.8B
2.31
1.56
2.9A
S/ton
8.37
13. S3
11.87
39.72
$/ton
4.51
1C. 17
6.54
14.68
-------
Figures 18 -through 21 show the relative costs of treatment for reduction
of effluent volumes and loads of the most critical pollutants from the
raw wastes before any treatment processes other than recirculation
and/or \water conservation methods. The most critical pollutants are
taken as suspended solids for Categories I, II, and III; and heat loads
for Category IV.
The costs of Level 1 Treatments were equaled r.o unity ana tne costs of
the other Levels expressed as their costs relative to unity. As the
curves show, more costly treatment do^s net necessarily result in volume
load reductions.
These curves provide graphical inicrmation of inter-st, out must be read
in the context of the previously uescribec Treatment Levels to be of
value.
139
-------
FIGURE 18.
COST OF TREATMENT vs. EFFLUENT REDUCTION
CATEGORY I
W
•u
03
0
3
C
C
(D
e
j_i
(0
(U
(J
H
eu
>
•H
4->
(fl
rH
0)
3.0
2.0
1.0 ^=
% Effluent Volume Reduction
20 40 60 80
99.0
. I
99.5
Suspended Solids Reduction
100
O ft*
100.0
** Includes cost of air pollution control system.
-------
FIGURE 19.
COST OF TREATMENT vs. EFFLUENT REDUCTION
CATEGORY II
1.4
0
CO
2 1.3
fl)
3
C
c
a 1.2
91
e
U
ca
H
0)
oi
1.1
1.0
98
Effluent Volume Reduction
20
40
~r
.60
98.5 99 99.5
% Suspended Solids Reduction
._JJ)0
100,
-------
- FIGURE 20.
COST OF TREATMENT vs. EFFLUENT REDUCTION
CATEGORY III
CO
CO
u
c
G
c
-------
FIGURE 21.
COST OF TREATMENT vs. EFFLUENT REDUCTION
CATEGORY IV
u»
•14.0
0)
o
o
12.0
3
B
« 8.Oh
% !•
(0
0)
20
"i
% Effluent Volume Reduction
80
40
i
60
i
100
«
iH
OJ
4.0 -
1.0
I
20
40 60
Heat Content Reduction
l
80
100
-------
INCREMENTAL COSTS OF ACHIEVING LEVELS OF TREATMENT TECHNOLOGY
The cost of achieving the various levels of treatment technology in the
industry will vary from piant-to-plant, depending upon the treatment
currently in use. The best estimates of these costs are given below by
Category, based upon the assumed levels of present technology in
"typical" plants.
Category I
The "typical" plant probably has a lagoon in which the scruober waste-
water is treated by plain sedimentation prior to discharge. Although
this 'typical' lagoon may be usable as part of a new treatment scheme,
it is likely that almost all of the costs shown in Table 97 would be
incurred to bring "the plant's effluent down to .the suggested limitation.
If the plant were to go to Level 2 from this base, it would require only
the addition of .a sand filter and recirculation system, i.e., the
arithmetic difference in costs between Levels 1 and 2. Therefore, the
incremental cost of reaching Level 1 would be $17,143/mw in investment,
and $0.859/mwhr in annual costs. The incremental cost of reaching Level
2 would be $3,,920/mw for investment, and $0.197^mwhr in annual costs.
Category II
The "typical" plant probably has a lagoon in which the scruboer waste
water is treated by sedimentation and for destruction of cyanides prior
to discharge. Again, it may be assumed that the cost of reaching Level
1 is 100% of that shown, and the cost of reaching Level 2 from Level 1
is the arithmetic difference. Therefore, the incremental cost of
reaching Level 1 would be $22,222/mw in investment, and.$ 1.113/mwhr in
annual costs. The additional costs to reach Level 2 woula be i5,081/mw
in investment, and $0.255/mwhr in annual costs.
Category III ~
The "typical" plant again for this Category probably has a small lagoon
and would probably require expenditure of 100% of the costs shown, which
makes the incremental cost for Level 1 $2,526/tpd for investment, and
$1.28/ton for annual costs. To reach Level 2 would require an
additional investment of $78/tpd, and increase annual costs by $0.03.
Category IV
The "typical" plant may be assumed to have once-through cooling water
use at no cost. The incremental costs to reach Level 1 Treatment
Technology would be $1,266 per mw for investment and $0.017 per mwhr for
total annual costs. A cooling tower would be a wise alternative to a
cooling pond. The incremental costs for a cooling tower system (Level
2) would be $8,444 per mw for investment and $0.512 per mwhr for annual
operating costs.
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ENERGY AND NON-WATEF QUALITY ASPECTS
There are significant energy and nonwar.er quality aspects to the
selection and operation ot treatment systems. These may t>e considered
as land requirements, air and solid wasts aspects, oy-product
requirements, air
potentials, and energy requirements.
Land
One of the most important aspects in the selection ot wastewater
treatment systems in this industry is the land required for cooling
ponds and water treatment systems. Many plants in the industry have
extensive land areas available for such uses and may elect this
generally lower cost treatment alternative. Other plants do not have
land readily available and would have to select alt=rnatj.ve treatment
systems such as cooling towers rather than ponds and tnt use of filters
for sludge dewatering, rather than sludge lagoons, for tnis reason
alone.
Air and Solid^Wastes
The solid waste produced by treatment of waste waters in the industry
derives principally from the smelting operation as waste from air
pollution control devices. The solid waste from air pollution controls
is produced whether a dry or wet system is utilized and varies only in
that the former produces a slurry or sludge, the latter a fine dust.
The slurry or sludge is generally accumulated in sludge lagoons, while
the dry dust may be bagged and landfilled or simply piled. More careful
attention should be directed to the disposal of these potentially
harmful materials. Possible improvements might be iandfilling in a
sealed site, or encapsulation in concrete or polymers. Tnere has been
little success in efforts to agglomerate these solids for recharging to
the smelting furnaces, although it is probable that dry dust could be
utilized more easily than wet sludge.
By-Product Potentials
In the case of metals refining at one plant, a baghouse is to replace a
wet scrubber and the particulate matter is to be leached to produce the
electrolyte for electrolytic manganese production. Trie potential for
such recovery methods is probably very limited, since this refining
process is not a common operation. The use of particulates in furnace
charges is not actually being done yet.
Slag concentration is used at a number of plants to recover metal values
and as a by product, to produce slag for sale or other use. The sale or
use of slag varies from place to place. In one location slag can be
readily -sold at a good price, since stone must be imported from a
distance. This is probably not a common situation. At another plant
145
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all of the slag produced is used on-site for road building. At other
plants, markets or uses for slag cannot be found.
By-product recovery in the case of the further use of the metals
refining particulates reduces a solid waste problem and does nor add to
potential water pollution, since the particulates" replace ore in an
electrolytic process. Slag concentration reduces solid wastes, but
results in a water pollution potential not otherwise present.
Energy Requirements
The use of recirculation cooling water systems is primarily due to water
supply limitations. Plants that use well water supplies generally do
not have enough water for once-through cooling systems. Those which use
purchased city water find that water costs favor recirculating systems.
One plant uses well water and recirculation with cooling towers in
preference to pumping river water over a distance of almost one mile.
Those plants which have installed facilities for thermal pollution
abatement have used cooling ponds. In cases where land availability for
cooling ponds might be a problem, spray canals or cooling towers are
alternatives to cooling ponds for thermal pollution abatement. In
considering alternative thermal pollution abatement methods, the
relative energy requirements may be significant.
Power requirements for waste water treatment systems otiier than cooling
towers are generally low. Power uses range from less than 0.1% to 1.3%
of the power used in the smelting furnaces. The higher figure is for
the most power-intensive system found during the survey, which uses
clarifier-flocculators, sand filters, softening, and recirculation of
process water. The lower figure is for a system using lagoons, a
clarifier-flocculater, and recirculation. The power requirements for
cooling towers reportedly range up to about 1.8% of the power used in
the smelting furnaces. Power requirements for the use of the most
power-intensive treatment systems for process and cooling water could
thus amount to 3% of the power used in production. This compares with
the use of 10% of the productive power for operation of high-energy
scrubbers for air pollution control. Based on pressure drops, the power
requirement for dry dust collectors is one-third or half that for high
energy scrubbers.
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SECTION IX
BEST PRACTICABLE CONTROL TECHNOLOGY CURRENTLY AVAILABLE,
GUIDELINES AND LIMITATIONS
INTRODUCTION
The effluent limitations which musr be achieved by July 1, 1977 are to
specify the degree of effluent reduction attainable through the
application of the Best Practicable Control Technology Currently
Available. This is generally based upon the average of the best
existing plants of various sizes, ages and unit processes within the
industrial category and/or subcategory.
Consideration must also be given to:
a. The total cost of application of technology in relation to the
effluent reduction benefits to ce achieved from such application;
b. the size and age of equipment and facilities involved;
c. the processes employed;
d. the engineering aspects of the application of various types of
control techniques;
e. process changes;
1". non-water quality environmental impact (including energy
requirements) .
Also, Best Practicable Control Technology Currently Available empnasizes
treatment facilities at the end of a manufacturing process but includes
the control technologies within the process it.self when the latter are
considered to be normal practice within an industry.
A further consideration is the degree of economic and engineering
reliability which must be established for the tecnnology to be
"currently available." As a result of demonstration projects, pilot
plants and general use, there must exist a high degree or confidence in
the engineering and economic practicability of the tecnnology at the
time of commencement of construction or installation of tne control
facilities.
EFFLUENT REDUCTION ATTAINABLE THROUGH THE APPLICATION OF BEST
PRACTICABLE CONTROL TECHNOLOGY CURRENTLY AVAILABLE (BPCTCA)
147
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Based upon the information contained in Sections III tnrough VIII of
this report, a determination has been made that the degree of effluent
reduction attainable through the application of the best practicable
technology currently available is the application of the levels of
treatment described in Section VII as the Level I tecnnologies to the
various industry categories as shown in Table 100.
Table 100. BPCTCA EFFLUENT GUIDELINES TREATMENT BASIS
Industry__CategorY_ Treatment Basis
I Chemical treatment, clarifier-flocculators,
recirculatior. at the scrubber
II Chemical treatment, clarifier-flocculators
III Clarifier-flocculators
IV Reduction of temperature rise
to 2.6°C (5°F)
Category I
New, larger open furnaces have been equipped with high-energy scrubbers
when wet air pollution controls have been selected. The water use at
the scrubber is high due to the volume of the off-gases to be treated,
but the waste water effluent volume is reduced by recircuiation at the
scrubber and this lowered volume is that to be treated for discharge.
The costs here would be those given in Tables 97 and 98, Category I,
Treatment Level 1. The alternative use of steam/hot water scrubbers or
electrostatic precipitators should result in even less costs if
treatment is for discharge, since waste water volumes would be less.
Although the entire treatment system is not presently in use at any one
plant, portions of the suggested technology as shown in Figure 17 are
readily transferable from other plants within this industry. No
innovative or new technology is involved - rather, the application of
existing and fairly pedestrian technology to this industry's problem.
Category II
Covered furnaces have generally been equipped with disintegrator
scrubbers in the past, although some of the newer furnaces are equipped
with high energy scrubbers. The volume to be treated for discharge was
taken as that of Plant B, sample point D. As in Category I, the usage
of steam/hot water scrubbers should significantly reduce treatment
costs, since water volumes would be less.
148
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Although the technology is not in use at any one plant, portions are in
use at various ferroalloys plants and should be readily transferable.
Category III
The loads attainable by the use of such technology described as Level 1
for this category are probably as good as could be expected if water is
used on a once-through basis. The. technology of clarification and
flocculation is, again, rather commonplace. Other methods for
sedimentation (such as lagoons) might be used for meeting the
recommended guidelines, if sufficient land is available. The suggested
technology, however, minimizes land requirements.
Category IV
Cooling ponds are in present use in at least one ferroalloy plant,
installed for thermal pollution abatement when once-througii cooling is
used. The relatively low cost can be justified en tne basis of the
large reduction (about 63%) of the thermal load to the stream. Where
land is not available for cooling por.os, spray canals (s^ray por.ds) or
cooling towers are alternatives.
Summary
The suggested Guidelines do not appear to present any particular
problems in implementation. The processes involved are all in present
use in ferroalloy plants, are common waste water treatment methods and
no engineering problems are involved in design or construction. Process
changes are not required in any existing plants and the size or age of
facilities has little or no bearing on the applicability of these
.methods.
Some additional solid wastes are generated by the suggested treatment
methods since better treatment than is presently practiced as proposed.
Power consumption for treatment is about 1% of that usea in the
furnaces.
The effluent limitations here apply to measurements taK«=n at the
of the last waste water treatment process unit.
outlet
The effluent loads, together with estimated costs applicaole to the Best
Practicable Control Technology Currently Available Guidelines and
Limitations are summarized in Table 101.
APPLICATION OF LIMITATIONS
The application of these guidelines and performance standards to
specific plants is intended to be or. the basis of a "building block."
1U9
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approach to define the effluent limits from the plant as a whole.
Consider, for example, a ferroalloy plant with the following processes:
30 mw open furnace with an electrostatic precipitator with water sprays
20 mw open furnace with a baghouse
15 mw covered furnace with a scrubber
Slag concentrating, feed rate 9.07 kkg (10 tons)/hr
Exothermic smelting, producing 4.54 kkg (5 tons)/day.
The total permissible load of suspended solids would be calculated by
Category as follows:
Category I: (30 X 24) mwhr/day X 0.352 Ibs/mwhr = 254 j.bs/day
Category II: (15 X 24) mwhr/day X 0.461 Ibs/mwhr = 166 Ibs/day
5 ton/day X 3 X 0.461 Ib/ton product = 7 lo/day
Category III: 10 tor./hr X 24 hr/day X 2.659 It/ton processed = 638 Ib/day
Category IV: 24(30 + 15 + 16) mwhr/day X 2.959 Ibs/mwhr= 4,620 Ibs/day
Total plant load, Ibs/day suspended solids= 5,685 ibs/aay
(2,580 ky/day)
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Table 101. BEST PRACTICABLE CONTROL TECHNOLOGY CURRENTLY AVAILABLE
GUIDELINES AND LIMITATIONS
CATEGORY I
30 Day Average 24 hr Maximum
CATEGORY II
30 Day Average 24 hr Maximum
CATEGORY III
30 Day Aver- 24 hr Max.
CATEGORY IV
30 Day Average 24 hr Maximum
kg/mwhr Ib/mwhr kg/nwhr Ib/mwhr kg/mwhr Ib/mwhr kg/mwhr Ib/mwhr kg/kkg Ib/ton kg/kkg Ib/ton kg/mwhr Ib/mwhr kg/mwhr Ib/mwhr
Constituent proc. proc. proc. proc.
Suspended Solids
Total Chromium
Hexavalent
Chromium
Total Cyanide
Manganese
Oil
Phenol
Phosphate
pH
.160
.0032
.0002
.032
.045
.0032
.0064
.352
.007
.0004
.070
.098
.007
.0141
6.0-9.0
.319
.006
.0006
.064
.064
.004
.013
.703
.014
.0014
.141
.141
.010
.028
0.209
0.004
0.0003
0.002
0.042
0.059
0.004
0.008
.461
0.009
0.0006
0.005
0.092
0.129
0.009
0.018
6.0-9.0
0.419
0.008
0.0008
0.004
0.084
0.084
0.006
0.017
0.922
0.018
0.0018
0.009
.184
0.184
0.013
0.037
1.330
0.026
0.266
0.372
2.659
0.053
0.532
0.745
6.0-9.0
2.659
0.053
0.532
0.532
5.319
.106
1.064
1.064
1.343
0.027
0.002
0.376
0.161
2.959
0.059
0.004
0.828
0.355
6.0-9
2.686
0.054
0.005
0.537
0.269
.0
5.917
0.118
0.012
1.183
0.592
kg-cal/ BTU/
mwhr mwlir
kg-cal/ BTU/
r.iwhr mwhr
Heat Content
Cost Items
Investment
Capital Costs
Depreciation
Operating Costs
Less Power
Power Ci-Sts
fot.il Operating
Costs
149,000 592,000 298,000 1,184,000
$/mw
17,143
_$/mwhr_
0.103
0.138
0.606
0.012
0.859
$/mw
22,222
$/mwhr
0.134
0.178
0.785
0.016
1.113
$/ton/day
2,526
$/ton
0.344
0.459
0.421
0.051
1.28
$/mw.
1,266
$/mwhr
0.007
0.010
0.0
0.0
0.017
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S1-.CTIOM X
BEST AVAILABLE TECHNOLOGY ECONOMICALLY ACHI-c.V/ibL£.,
GUIDELINES AND LIMITATIONS
INTRODUCTION
The effluenr limitations which must be achieved by July 1, 1963 are t.o
specify the degree of effluent reduction attainable through the
application of the Best Available Technology Economically Achievable
(BATEA). BATEA is determined by the very best control and treatment
Technology employed by a specific point source witnin trie industry
category or by technology which is readily transferable irora another
industrial process.
Consideration must also be given to:
a. The age of equipment and facilities involved;
b. the process employed;
c. the engineering aspects of the application of various types of
control techniques;
d. process changes;
e. cost- of achieving the effluent reduction resulting from the
application of this level of technology;
f. non-water quality environmental impact (including energy
requirements).
Also, Best Available Technology Economically Achievable assesses the
availability of in-process controls as well as additional treatment at
the end of a production process. In-process control options include
water re-user alternative water uses, water conservation, by-product
recovery, good housekeeping, and monitor and alarm systems.
A further consideration is the availability of plant process changes and
control techniques up to and including "no discharge" of pollutants.
Costs for this level of control are to be the top-of-the-line of current
technology subject to engineering and economic feasibility.
EFFLUENT REDUCTION ATTAINABLE THROUGH THE APPLICATION OF £>hST AVAILABLE
TECHNOLOGY ECONOMICALLY ACHIEVABLE (BATEA)
Based upon the information contained in Sections III through VIII of
this report, a determination has been made that the degree of effluent
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reduction attainable througn th- at I'licarion or t/est available
technology economically achievable is r.i -: £? plicsrion 01 tne levels of
treatment described in Section VII as; T.fvf.l 2 to the various industry
categories as shown in Table 102.
Table 102. BATEA EFFLUENT GUIDELINES TREATMENT BASIS
_Industr%JC ategory
I
II
III
IV
Cht-.Hi2C£l *rva~.iTir.-r:t, clariiier-ilocculators,
Sc.r.d fii-r^rfe, ir-circuiation
cr.enucal rr<~-arn;-:r:t, clariiier-
iloccuia-crs, sand filters, recirculation
Prcce-sfe v»atir r-citculation
Cooling towers, r-rcircularion,
tmcnt of t iowuown
These guidelines nave been sel
considerations and assumptions.
Category I
basis or tne rollowing
The effluent load reduction above Level I is primarily due to the
effluent reduction attained through recircule-tion of tne scrubber water,
although some of the reduction is due to lower concentrations in the
effluent. Portions of the technology described are in use at various
ferroalloys plants, and no new or innovative technology is required.
Consideration was given in Category I to the replacement of existing
scrubbers with fabric filter collectors, which would result in zero
discharge of pollutants. However, the large investment costs required
(from $1.19 to 2.34 million for a 30 mw furnace vs approximately $.632
million for a scrubber waste water treatment system) probably makes this
technology economically unachievable, particularly so when it would
cause the premature retirement of existing air pollution control
systems.
Category II
Again, load reduction above Level I is due primarily to the reduction in
effluent volume attained by recirculation. . Althougn Plant C was
achieving 97% recirculation of the scrubber water, this high a
proportion may not be feasible for all plants and the standard was so
selected. As before, no innovative technology is required.
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Category III
Since water is used only as a transport or cooliny medium in slag
processing, the quality of recirculated water is of importance only to
the extent of its abrasiveness on valves and pumps. Operation with no
water discharge, i.e., complete recirculation and reuse is practiced at
least at one plant . The engineering problems are trivial, requiring
only recirculation pumps and clarifier-flocculators close to the slag
processing equipment.
Category IV
Cooling water recirculation and reuse is suggested in Treatment Level 2
as being accomplished by the use of cooling towers witn treatment of the
blowdown for removal of chromates or phosphates. This level or effluent
reduction could also be achieved through the use of spray canals such as
are used in some electric power plants. The costs given are thus
conservatively high and are based upon methods in current use. Such
technology is straightforward and readily available.
Summary
The suggested Guidelines present no particular problems in
implementation from an engineering aspect and require no process
changes. Water reuse and good housekeepina are empnasized. Age of
equipment and facilities are of no particular importance.
No additional solid wastes of significance are created by the suggested
treatment methods. Increased power consumption may amount to as much as
3*1 of furnace power in the most energy intensive water treatment system.
The effluent limitations here apply to measurements taken at the outlet
of the last waste water treatment process unit. It is not judged to be
practical to require the treatment or ccntrol of runoff due to storm
1 water for the 1983 standards for existing plants. Sucri treatment or
control would be very difficult to accomplish in older plants having
many years of accumulations of slag, collected airborne particulates,
etc. Depending upon the geography of a plant site and tne acreage
involved, costs would vary widely from plant to plant. Some such
containment as earthen dikes around production areas could conceivably
be used. In one steel mill where it was proposed to collect runoff and
treat the collected water in a lagoon, the costs involved were equal to
the total expenditures for a minimum discharge recirculation system.
The effluent loads, together with estimated costs, applicable to the
Best Available Technology Economically Achievable Guidelines are
summarized in Table 103.
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APPLICATION OF LIMITATIONS
The application of these guidelines and performance standards to
specific plants is intended to be on the basis of a "building block"
approach to define the effluent limits from the plant as a wnole. The
application is as illustrated under Best Practicable Control Technology
Currently Available in Section IX, except that with Best Available
Technology Economically Achievable, the permissible suspended solids
load for the hypothetical plant would be 263 Ib/day* rather than 5,685
Ib/day.
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Table 103 BEST AVAILABLE TECHNOLOGY ECONOMICALLY ACHIEVABLE
GUIDELINES AND LIMITATIONS
cn
CATEGORY I
30 Day Average 24 hr Maximum
kg/mwhr Ib/mwhr
Suspended Solids
Total Chromium
Hexavalent
Chromium
Total Cyanide
Manganese
01;
Phenol
Phosphate
pH
Heat Content
.012 .026
.0004 .0009
,00001 .00002
kg/mwhr Ib/mwhr
.024 .052
.0008 .0017
.00002 .00004
.0039
.0055
.0002
.0001
.0086
.012
.0003
.0002
.008
.008
.0003
.0002
.017
.017
.0007
.0003
6.0-9.0
CATEGORY II
30 Day Average 24 hr Maximum
kg/mwhr
0.016
0.0005
0.00001
0.0003
0.005
0.007
0.0002
0.0001
Ib/mwhr
0.035
0.0012
0.00002
0.0006
0.012
0.016
0.0005
0.0002
6.0-9
kg/mwhr
0.032
0.001
0.00002
0.0005
0.011
0.011
0.0004
0.0002
.1)
Ib/mwhr
0.071
0.002
0.00005
0.001
0.023
0.023
0.0009
0.0005
CATEGORY IV
30 Day Average 24 hr Maximum
kg/mwhr Ib/mwhr
0.067 0.148
0.001 0.003
0.00003 0.00006
kg/mwhr Ib/mwhr
0.134 0.296
0.003 0.006
0.00005 0.0001
0.019
0.004
0.041
0.009
6.0-9.0
0.027
0.008
0.059
0.018
kg-cal/ BTU/
mwhr mwhr
7,500 30,000 14,900 59.000
kg-cal/ BTU/
mwhr mwhr
Cost Item
Investment
Capital Costs
Depreciation
Operating Costs
Less Power
Power Costs
Total Operating
Costs
$/mw
21,063
$/mwhr
0.127
0.169
0.745
0.015
1.056
$/mw ,
27,303
$/mwhr
0.165
0.219
0.965
0.019
1.368
$/mw
8,444
$/mwhr
0.049
0.065
0.354
0.044
0.512
Category III: No discharge of waste water pollutants to navigable waters. Costs as shown in Table 97.
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SECTION XI
NEW SOURCE PERFORMANCE STANDARDS
AND PRETREATMENT STANDARDS
INTRODUCTION
The effluent limitations which must, be achieved by new sources, i.e.,
any source, the construction of which is started after publication of
new source performance standard regulations, are to specify the degree
of treatment available through the use of improved production processes
and/or treatment techniques. Alternative processes, operating methods
or other alternatives musr. be considered. The end result j.s to identify
effluent standards achievable through the use of improved production
processes (as well as ccnt.ro! technology) . A further determination
which must be made for new source performance standard is whether a
standard permitting no discharge of pollutants is practicable.
Consideration must also be given tc:
a. The type of process employed and process changes;
b. operating methods;
c. batch as opposed to continuous operation;
d. use of alternative raw materials arid mixes of raw
materials;
e. use of dry rather than wet processes;
recovery of pollutants as by-products.
In addition to recommending new source performance standards and
effluent limitations covering discharges into waterways, constituents of
the effluent discharge must be identified which would interfere with,
pass through or otherwise be incompatible with a well designed and
operated publicly owed activated sludge or trickling riiter waste water
treatment plant. A determination must be made as to whether the
introduction of such pollutants into the treatment plant should be
completely prohibited.
EFFLUENT REDUCTION ATTAINABLE THROUGH THE APPLICATION OF NEW SOURCE
PERFORMANCE STANDARDS
Based upon the information contained in Section III through VIII of this
report, a determination has been made that the degree of effluent
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reduction attainable by new sources is the same achieved by application
of the levels of treatment described in section X and/or the attainment
of zero discharge of waterborne pollutants to navigable waters in the
various industry categories as shown in Table 104.
Table 104. NEW SOUF.CE PERFORMANCE STANDARDS tASIS
.Indus try_Cat^cjory._ Treatment Pa sis
I Baghouse for Air Pollution Control
II Chemical treatment, ciarifier -
flocculatcrs, sand filters, recalculation.
Ill Process water recircularion
IV Pecirculation through cooling towers,
chemical treatment of blowdown
performance standards have teen selected on the basis of the
following assumptions and considerations.
Category I
Baghouses on open furnaces achieve air pollution abatement levels at
least as good or better than these of scrubbers and, or course, produce
no waste water effluents. Industry representatives indicated during the
study that this is the method of choice in the face of more stringent
effluent quality limitations than were previously in effect when wet
scrubbers have been selected.. No significant engineering or other
technical problems are involved; this technology is state-c£-tne-art and
is in wide use in the industry. In fact, it is more common to equip an
open furnace with a baghouse than with a scrubber. Additionally, the
annual costs for a fabric filter system are about half tnose of a
scrubber system with waste water treatment, and the power requirements
are half or less those for a high energy scrubber.
Category II
Although the possibility remains of developing baghouses which are
explosion-proof and thus applicable to covered furnaces, it is by no
means clear that this is a practical alternative. There is one such
baghouse on a covered furnace in the world, but none in the United
States. One other furnace utilizes a "candle filter" (ceramic filter)
for dry cleaning of CO gas. At this time, and with only two closed
furnaces in the world so equipped, it does not seem practical to require
the use of a dry dust collection system. Therefore, the treatment level
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specified tor EATEA, Category II appears to te t.riat wnj.cn will minimize
waste discharge.
Category III
Since the treatment level specified for BATEA is zc.ro discharge of
pollutants, this is the n=w source performance standard.
Category IV
Recirculation of cooling water through cooling towers or tne use of
spray canals as specified for BATE A is T. he only clearly available
technology. The possibility of using dry cooling towers exist. Since a
dry cooling tower does not evaporate any of The cooled water, tnere is
no concentration effect and no blowdown is necessary. however, tne cost
of such systems as would be required in this industry is sucn tnat it
would probably be unfeasible. Dry cooling towers are not a likely
alternative unless specified for industry generally ana thus available
readily from equipment manufactures. Th-r- BATFA treatment has thus been
selected as the basis for limitations from new sources.
SUMMARY
The suggested new source performance standards consider tne means by
which no discharge of waterfcorne pollutants to navigable waters can be
achieved. Such "no discharge" standards are clearly available for 2
categories (I and III) and are so specified. Standards of perrormance
for the other two categories are those which will minimize waste
discharge.
The effluent loads, together with estimated costs, applicable to the New
Source Performance Standards are summarized in Table 105.
For the new source, performance standards, it should be additionally
specified that all measurements taker: for purposes of meeting the
effluent limits should be at the plant outfall, if the new source is a
new plant. This means, in effect, that run-oft from materials handling
and storage, slag piles, collected air borne particulates, and general
plant areas must be collected and treated or that storm water must not
initially contact such sources of pollutants. Such control measures can
rather easily be built into new plants, but would be very difficult to
accomplish in older plants, having many years of accumulation of slag,
collected airborne particulates, etc. Practical control measures might
include impoundment of storm water and use of such water as an intake
source or landfill of waste particulates. The option of treating runoff
to meet the effluent standard would, of course, be available. If the
new source is part of an already existing plant, i.e., a new furnace,
all measurements should be taken after the last waste water treatment
process unit. These standards should te applied by the "building block"
approach, as discussed in section IX. If the hypothetical plant of that
161
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section were a new source, the permissible suspended solids discharge
would be 244 Ib/day.
PRETREATMENT STANDARDS
The pretreatment standards under section 307(c) of the Act, for a source
within the ferroalloy industry which is an industrial user of a publicly
owned treatment works (and which would be a new source subject to
section 306 of the Act, if it were to discharge to navigaole waters) ,
shall be the standard set forth in Part 128, 40 CFk, except that the
pretreatment standard for incompatible pollutants shall be the standard
of performance for new sources of that subcategory. If tne publicly
owned treatment works is committed, in its MPDES permit, to remove a
specified percentage of any incomeatitle pollutant, the pretreatment
standard applicable to users of such treatment works snail be
correspondingly reduced for that pollutant.
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Table 105 NEW SOURCE PERFORMANCE STANDARDS
CTi
U)
Suspended Solids
Total Chromium
Hexavalent
Chromium
Total Cyanide
Manganese
Oil
Phenol
Phosphate
PH
0.016
0.0005
0.00001
0.0003
0.005
0.007
0.0002
0.0001
0.035
0.0012
0.00002
0.0006
0.012
0.016
0.0005
0.0002
6
CATEGORY II
30 Day Average 24 hr Maximum
kg/mwhr Ib/mwhr kg/mwhr Ib/mwhr
0.032
0.001
0.071
0.002
0.00002 0.00005
0.0005
0.011
0.011
O.OG04
0.0002
6.0-9.0
0.001
0.023
0.023
0.0009
0.0005
CATEGORY IV
30 Day Average 24 hr Maximum
kg/mwhrIb/rowhr
kg/mwhr lb/r.iwhr
0.067
0.001
0.148
0.003
0.134
0.003
0.296
0.006
0.00003 0.00006
0.00005 0.0001
0.059
0.018
kg-cal/ BTU/ kg-cal/ BTU/
mwhr mwhr mwhr mw'nr
7,500 30,000 T579UU~ 59,000
0.019
0.004
0.041
0.009
6
0.027
0.008
.0-9.0
Cost Item
Investment
Capital costs
Depreciation
Operating Costs
Less Power
Power Costs
Total Operating
Costs
$/mw
27,303
$/mwhr
0.165
0.219
0.965
0.019
1.368
$/mw
8,444
$/mwhr
0.049
0.065
0.354
0.044
0.512
Categories I and III: No discharge o$ waste water pollutants to navigable waters. Costs as shown in Table 97 and 99.
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SECTION XII
ACKNOWLEDGEMENTS
The Environmental Protection Agency would like to thank Dr. h.C. Bramer
and Messrs. E. Shapiro and N. Elliott cf Datagraphics, Inc. for their
aid in the preparation of this report. Thanks are also given to the
sampling crews (Messrs. D. Bramer, D. Riston, C. Casweii, E. D. Escher,
E. Brunell, et al) . Special thanks is also given to Ms. Darlene Speight
of Datagraphics, Inc. and Mrs. Nancy Zrubek ot EPA for tneir long, late
hours spent in the typing and retyping of this report.
The author would like to thank her associates in the Erfluent Guidelines
Division, particularly Messrs. Edward Dulaney, Wa.lter J. hunt, Ernst P.
Hall, and Allen Cywin for their helpful suggestions and assistance.
Thanks also are expressed to Messrs. George A. Watson and Archur M.
Killan of the Ferroalloys Association for their valuable assistance.
Acknowledgement and appreciation is extended to those personnel of the
industry who cooperated in plant visitations and supplying of data
including Dr. R.A. Person, Dr. C.R. Allenbach and Messrs. R. Bilstein
and J.E. Banasik of Union Carbide Corporation; L.C. Wintersteen, W.A.
Moore, and L.A. Davis of Airco, Inc.; F.D. Turner ana W.A. Witt of
Chromium Mining and Smelting Corporation; C.G. Adler and £.W. Batchelor
of Foote Mineral Company; F. Krikau and J.C. dine of Interlake, Inc.;
and C.F. Seybold, M. Evans, and L. Risi of Shieldalloy.
Appreciation is also expressed to Mr. H. Fathman wno acted as a
consultant to Datagraphics, Inc. and provided invaluaole assistance in
preparation of this report.
Thanks are also given to Messrs. K. Durkee and J.O. Dealey of the Office
of Air Programs, EPA, for their assistance during the course of this
study.
Thanks are also given to the members cf the EPA Working Group/Steering
Committee for their advice and assistance. They are: Messrs. A.
Brueckmann, S. Davis, M. Dick, T. Powers, P.. Zener, E. Lazar and Dr. H.
Durham.
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SECTION XIII
1. Compilation of Air Pollutant Emission Factors, U.S. Environmental
Protection Agency, Office of Air Prcqr ams , February, ±^12 (N.T.I.S. No.
PB-209 559) .
2. Sherman, P. R. & Springman, E. P., "Operating Proolems witn High
Energy Wet Scrubbers on Submerged Arc Furnaces", a paper presented at
the American Institute of Metallurgical Engineers hiectric Furnace
Conference, Chicago, Illinois December, 1972
3. Scherrer, R. E. , "Air Pollution Control for a Calcium Carbide
Furnace", A.I.M.E. Electric Furnace Ircc~--dir.gs, Volume 27, Detroit,
1969, pages 93-98
4. Seybold, Charles F. , "Pollution control Equipment, for Tnermite
Smelting Processes", A.I.M.E. Electric Furnace Proceedings, Volume 27,
Detroit, 1969, pages 99-108
5. Person, R. A., "Control of Emissions from Ferroalloy Furnace
Processing", A.I.M.E. Electric Furnacf Proceedings, Volume 27, Detroit.
1969, pages 81-92
6. Fetelsdorf, H. J. , Hodapp, E. , & Enciell, N. , "Experiences with an
Electric Filter Dust Collecting System ir. Connection with a 20-MW
Silicochromium Furnace", A.I.M.E. Elec-ric Furnace Proceedings, Volume
27, Detroit, 1969, pages 109-114.
7. Gamroth, R. R., "Operation of 30,000 - KW Submerged Arc Furnace on
Silicomanganese", A.I.M.E. Electric Furnace Proceedings, Volume 27,
Detroit, 1969, pages 164-166
8. Dehuf f , J. A., Coppolecchia, V. D,, & Lesr.ewich, A., "The Structure
of Ferrosilicon" , A.I.M.E. Electric Furnace Proceedings.
9. "Annual Statistical Report - American Iron and Steel Institute -
1970", A. I.S.I., Washington, D. C. 80 pages
10. " 1967 Census of Manufactures - Blast Furnaces, Steel WorKS, and
Rolling and Finishing Mills", U. S. Department of Commerce, Bureau of
the Census, MC67 (2) - 33A, 48 pages
11. Elyutin, V. P., et al "Production of Ferroalloys Electro-
metallurgy", Translated from Russian by the Israel Program for
Scientific Translations, U. S. Department of Commerce,
167
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12. "Water Use in Manufacturing", 1967 Ctrsus of .'Icaiuractures, U.S.
Department of Commerce, Bureau of the Census, Mr. 67 (1) -7, April, 1971,
361 pages.
13. Ferrari, Renzo, "Experiences in Developing an Efrective Pollution
Control System for a Submerged Arc Ferrcally Furnace Operation", Journal
of Metals, April, 1968, pp. 95-104.
14. "Statement for Relief from Excessive Imports" The Ferroalloys
Association, Washington, D. C. 1973, 15 pages.
15. Communications with Mr. Edwin I. Kissmaii of General Technologies
Corporation - Trip Peport from the Astafcula, OKio plant, oi Union Carbide
Corporation, February 14, 1973.
16. Braaten, O. and Sandberg, C., "Progress in Electric Furnace
Smelting of Calcium Carbide and Ferroalloys", 5rh International Congress
on Electro-Heat, 7 pages.
17. Scott, J. W. , "Design of a .35,000 F. V*. High Caroon Ferrochrome
Furnace Equipped with an Electrostatic i'recipitotor", Tne Metallurgical
Society of A.I.M.E., pap^.r No. EFC-2, 9 pag<-s.
18. "A Study of Pollution Control Prc.crices in Manufacturing Industries
- Part 1 - Water Pollution Control", Lun 5 bradstreer.. Inc., June, 1971.
19. Blackmore, Samuel S., "Dust Emission Control Program Union Carbide
Corporation Metals Division", Air Pollution Control Association, 57th
Annual Meeting, June 21-25, 1964, 16 pages.
20. "Control Techniques for Emissions Containing Chromium, Manganese,
Nickel, and Vanadium" Office of Air Programs, Environmental Protection
Agency, January 12, 1973.
21. Mantell, C. L., "Electrochemical Engineering," McGraw-Hill Book
Company, Inc., 4the Edition, 1960, pages 468-533.
22. Person, R. A., "Emission Control of Ferroalloy Furnaces," Paper
presented at the 4th Annual North Eastern Regional Antipollution
Conference, July 13-15, 1971, 30 pages.
23. Smith, Robert & McMichael, Matter F., "Cost and Performance
Estimates for Tertiary Wastewater Treating Processes" -, United States
Dept. of Interior, Federal Water Pollution Control Administration, June,
1969, 27 pages.
24. "Pretreatment Guidelines for the Discharge of Industrial Wastes to
Municipal Treatment.Works", Environmental Protection Agency, November
17, 1972, Draft Report.
168
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25. "Minerals Yearbook - 1970", United States Bureau or Mines, pages
513-518.
26. "Minerals Yearbook - 1967", United States Bureau or i>iines, pages
499-506.
27. "A New Process for Cleaning and Pumping Industrial Gases - The
ADTEC System", Aronetics, Inc., Tullahcma, Tennessee, 22 pages.
28. "Cleanup in Our Ferroalloy Plants", Union Carbide World, July 1972,
Vol. 5, No. 3, 16 pages.
30. "Annual Statistical Report - American Iron and Steel Institute
1972, A.I.S.I., Washington, D. C. pages U5-51.
31. Eckenfelder, W. W., "Water Quality Engineerings, Barenes and Noble,
New York (1970) .
32. "Air Pollution Control Engineering and Cost Study or" tne Ferroalloy
Industry" (Draft Report), 1973, U. S. Environmental Protection Agency,
Office of Air and Water Programs, Washing-ccn, D.C.
169
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SECTION XIV
GLOSSARY
Blocking chrome - A high 10-12 % silicon grade of HC Ferrocnromium, used
as an additive in the making of chromium steel where it 'blocks' (i.e.,
stops) the reaction in the ladle.
Charcje __ Chrome - A grade of HC ferrochromium, so called because it forms
part of the charge in the making of stainless steel.
Chrome ore - lime melt_ A melt of chromium ore and lime produced in an
open arc furnace and an intermediate in the production of -LC
f errochromium.
Cover ed_ furnace - An electric furnace with a water-cooled cover over the
top to limit the introduction of air which would burn tne gases from the
reduction process. The furnace may have sleeves at the electrodes
(fixed seals or sealed furnaces) with the charge introduced through
ports in the furnace cover, or the charge may be introduced through
annular spaces surrounding the electrodes (mix seals or semi-closed
furnace) .
Exothermic Process - Silicon or aluminum, or a combination of the two,
combine with oxygen of the charge, generating considerable heat and
creating temperatures of several thousand degrees in the reaction
vessel. The process is generally used to produce high grade alloys with
low carbon content.
Ferroalloy - An intermediate material, used as an addition agent or
charge material in the production of steel and other metals.
Historically, these materials were ferrous alloys, hence the name. In
modern usage, however, the term has been broadened to cover such
materials as silicon metal, which are produced in a manner similar to
that used in the production of ferroalloys.
Induction .furnace - Induction heating is obtained by inducing an
electric current in the charge and may be considered as operating on the
transformer principle. Induction furnaces, which may be low frequency
or high frequency, are used to produce small tonnages of specialty
alloys through remelting of the required constituents.
Open furnace - An electric submerged-arc furnace with the surface of the
charge exposed to the atmosphere, whereby the reaction gases are burned
by the inrushing air.
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Open^arc_furnace - Hear is generated in an open arc furnace by the
passage of electric arc either between two electrodes or oetween one or
more electrodes and the charge. The arc furnace consists of a furnace
chamber and two or more electrodes. The furnace chamber nas a lining
which can withstand the operating temperatures and which is suitable for
the material to be heated. The lining is contained within a steel shell
which, in most cases, can be tilted or moved.
Pre-baked electrodes - An electrode purchased in finished form available
in diameters up to about 130 cm (51 in.) . These electrodes come in
sections with threaded ends, and are added to the electroae column.
Reducing Agent - Carbon bearing materials, such as metallurigical coke,
low volatile coal, and petroleum coke used in the electric furnace to
provide the carbon which combines with oxygen in the charge to form
carbon monoxide, thereby reducing the oxide to the metallic form.
Self-baking electrode - The electode consists cf a sheet steel casing
filled with a paste of carbonaceous material quite similar to that used
to make prebaked amorphous carbon electrodes. The heat from the passage
of current within the electrode and the heat from the turnace itself,
volatilize the asphaltic or tar binders in the paste to make a hard
baked electrode.
Sintering - The formation of larger particles, cakes, or masses from
small particles by heating alone, cr by heating and pressing, so that
certain constituents of the particles coalesce, fuse, or otnerwise bind
together. This may occur in the furnace itself, in wnich case the
charge must be stoked to break up the agglomeration.
Steam/hot water^scrubber - A system for removing particulates from
furnace gases, where water is first heated by the gases to partially
form steam, and then intimately contacted with the dirty gases. The
scrubber water containing the particulates is then separated from the
cleaned gases, which are emitted to the atmosphere. This system is
characterized by a low water usage and pressure drop.
Stoking - The stirring up of the upper portion of the charged materials
in the furnace. This loosens the charge and allows free upward flow of
furnace gases.
Submerged-arc furnace - In ferroalloy reduction furnaces, the electrodes
usually extend to a considerable depth into the charge, hence such
furnaces are called "submerged-arc furnaces". This name is used for the
furnaces whose load is practically entirely of the resistant type.
Tapping - This term is used in the metallurgical industries for the
removal of molten metal from furnaces, usually by opening a taphole
located in the lower portion of the furnace vessel.
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Vacuum furnace - A furnace in which the charge can te brought to an
elevated temperature in a high vacuum. The high vacuum provides an
almost completely inert enclosure where the process or reduction and
sintering can occur.
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SUPPLEMENT A
CONSULTATIONS AND PUBLIC PARTICIPATION
Scope of_Consultations
Prior to the publication of the Development Document arid the proposed
regulations for the ferroalloy manufacturing industry, the following
agencies, groups, and corporations were given the opportunity to
comment:
1.A11 State and U.S. Territory Pollution Control Agencies.
2.Ohio River Valley Sanitation Commissicr:.
3.New England Interstate Water Pollution Control commission.
U.Hudson River Sloop Restoration, Inc.
5.Conservation Foundation.
6.Businessmen for the Public Interest.
7.Environmental Defense Fund, Inc.
8.Natural Resources Defense Council.
9.The American Society of Civil Engineers.
10.Water Pollution Control Federation.
11.National Wildlife Federation.
12.The American Society of Mechanical Engineers.
13.Department of Commerce.
14. Water Resources Council.
15.Department of the Interior.
16.U.S. Department of the Treasury.
17.The Ferroalloys Association.
18.Effluent Standards and Water Quality Information Committee.
175
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Industry Participation
No interim permit guidance had teen ic?!rued for this industry and initial
contact with representatives of the industry war. made in late February,
1973.
Plant visitations and sampling was conducted during Maren, April and May
of 1973. The contractor's draft rsporr was distributed to The
Ferroalloys Assocication and they were ask-rd '-o comment on the draft
report by August 1, 1973. Comments troni six of the companies affected
and the trade association were received by AuciuFt 20, 1973.
1. Various members of industry quesT.icr.ea The r ~-..juir ement o± ary dust
collectors for new sources oi oper. •el^ctrir furnaces. Tney contended
that usage of certain raw materials (high in chloriaes, fluorides or
sulfur) would require the use of a scrubber £cr effective air pollution
abatement. To the best of our knowledge tre.s-- raw materials are not
presently in use, and th-~ proposed standard is valia. It should be
recognized that these- standards will r e sub jf ct to periodic review, and
should such raw materials come iivcc utv:, this {[articular standard might,
of course, be subject to revisior..
2.Some industry representatives conter.ded that tne contractor's
recommended limitations and standards were restrictive as to product.
The proposed limitations and standards r>ow allow for production of any
product.
3.Some industry representatives requested that once-tnrougn noncontact
ccoling water be exempted from any limitations. Due to the large
quantities of heat which can be discharged from this source, it is felt
reasonable to limit such therrral pollution.
Industry, under Section 316 of the Act, can be granted less stringent
limitations for nonccntact cooling waters if it can be demonstrated "to
the satisfaction of the Administrator that any effluent limitation
proposed for the control of the thermal component of any discharge from
such source will require effluent limitations more stringent than
necessary to assure the protection and propagation of a balanced,"
indigenous population of shellfish, fish, and wildlife in and on the
body of water into which the discharge is to oe made." "The
Administrator may impose an effluent limitation under such sections for
such plant, with respect to the thermal component with such discharge
(taking into account the interaction of such thermal component with
other pollutants), that will assure the protection and propagation of a
balanced, indigenous population of shellfish, fish, and wildlife.in and
on that body of water."
4.Some industry representatives requested that the limitations and
standards take into account dissolved solids levels. Although certain
dissolved solids such as calcium and magnesium may present scaling
176
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problems, these can be controlled by softening. One plant, nowever,
recirculated 97 percent of its scrubber waste water after treatment, the
only blowdown being from the clarifier underflow. A uiast furnace
producing ferromanganese which was studied as part cf the iron and Steel
industry study had a closed recycle system for gas scrubuer water.
Dissolved solids levels were 70,bOC tc 82,300 mg/i .in the clarifier
overflow, with potassium levels of 24,000 -*-o 25,600 mg/i. If tnat blast
furnace system can operate successfully at those levels, this industry
should be able to operate at a level cf about 8,000 mq/i potassium.
Eff_luent Standards and Water Quality lBl^2iHl2iA2Ii B^visory_ Committee
Comments
Concern was expressed about th-i lack cf adequate existing waste
treatment plants, in the industry, and trie Coiwnitt.e ot/servea that the
normal practice of determining best practicable t=cnnology and best
available technology is not entirely applicable (in sucn case) . The
best practicable and best available technology base:s nave been reviewed,
and the conclusion reached that although no one pla^t is capable of
reaching environmentally acceptable levels rcr all parameters, an
amalgamation of the treatments at the plar.ts studied could meet such
levels.
Other Federal Agencies
The Department of the Interior commented that, the costs of treatment do
not appear to include costs for monitoring. This is quite true,
however, these costs would be incurred no matter which treatment method
was used.
The Department of Commerce suggested that the guidelines i>e issued as a
range of numbers (because of variations ir plar.ts, climates, etc.). No
climatic variations were found, except for thermal, and this variation
has been taken into account in the proposed guidelines. Variations in
plants have been allowed for — both by the building block approach and
by setting the guidelines to permit production of ail alloys. For
example, a plant producing manganese products will have no problem
meeting the guideline for chromium, and a chromium plant should
experience no difficulty with the regulation for manganese.
Public Interest Groups
The comments received from public interest groups were noncommittal.
Period for Additional_Cornments
Upon publication of the proposed regulations, interested persons will
have 21 days in which to comment on the proposed regulations.
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