EPA
Development Document for Effluent Limitations Guidelines
and New Source Performance Standards for the
SMELTING AND SLAG
PROCESSING
Segments of the
Ferroalloy Manufacturing
Point Source Category
FEBRUARY 1974
U.S. ENVIRONMENTAL PROTECTION AGENCY
Washington, D.C. 20460
-------
•* , •' fl
,#» * *
» 4,
-------
DEVELOPMENT DOCUMENT
for
EFFLUENT LIMITATIONS GUIDELINES
and
NEW SOURCE PERFORMANCE STANDARDS
FOR THE SMELTING AND SLAG PROCESSING
SEGMENTS OF THE
FERROALLOY MANUFACTURING POINT SOURCE CATEGORY
Russell Train
Administrator
Allen Cywin
Director, Effluent Guidelines Division
Patricia W. Diercks
Project Officer
February, 1974
Effluent Guidelines Division
Office of Air and Water Programs
U.S. Environmental Protection Agency
Washington, D.C. 20460
For sale by the Superintendent of Documents, U.S. Government Printing OfBce
Washington, D.C. 20402 - Price $2.10
-------
-------
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
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 for each
category and for the attainment of the suggested effluent guidelines and
new source performance standards.
111
-------
-------
CONTENTS
Section
I Conclusions 1
II Recommendations 3
III Introduction 7
IV Industry Categorization 45
V Waste Characterization 51
VI Selection of Pollutant Parameters 61
VII Control and Treatment Technology 67
VIII Cost, Energy and Non-Water Quality Aspect 131
IX Best Practicable Control Technology Currently 143
Available, Guidelines and Limitations
X Best Available Technology Economically 149
Achievable, Guidelines and Limitations
XI New Source Performance Standards and 155
Pretreatment Standards
XII Acknowledgements 161
XIII References 163
XIV Glossary 167
v
-------
FIGURES
No.. Page
1 Ferroalloy Production Flow Diagram 20
2 Submerged-Arc Furnace Diagram 24
3 Cross Section of Open Furnace 25
4 Flow Sheet LC Ferrochromium . 32
5 Vacuum Furnace for Ferroalloy Production 35
6 Induction Furnace Diagram 36
7 Plant A Water and Wastewater 71
8 Plant B Water and Wastewater 77
9 Plant C Water and Wastewater 82
10 Steam/Hot Water Scrubbing System 89
11 Plant D Water and Wastewater Systems 90
12 Plant E Water and Wastewater Systems 95
13 Plant F Water and Wastewater Systems 106
14 Plant G Water and Wastewater Systems
15 Diagram of "Wet Baghouse" System
16 Plant H Water and Wastewater Systems H6
17 Diagram of Waste Water Treatment System 122
18 Cost of Treatment Vs. Effluent Reduction 136
Category I
19 Cost of Treatment Vs. Effluent Reduction 137
Category II
20 Cost of Treatment Vs. Effluent Reduction 138
Category III
VI
-------
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
14 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
14 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
-------
22 Raw Waste Load - High Energy Scrubber 54
On Open Electric Furnace
23 Raw Waste Loads-Open Chromium Alloy Furnaces °5
with Electrostatic Precipitators
24 Raw Waste Loads for Covered Furnaces with 56
Disintegrator Scrubbers
25 Raw Waste Loads-Sealed Silicomanganese Furnace -"7
with Disintegrator Scrubber
26 Raw Waste Load-Covered Furnaces with Scrubbers
57
27 Raw Waste Loads-Aluminothermic Smelting with 58
Combination Wet Scrubbers and Baghouse
28 Raw Waste Loads-Slag Concentration Process 59
29 Pollutant Parameters for Industry Categories ^1
30 Characteristics of Surveyed Plants ^7
31 Analytical Data -SP A- Plant A Lagoon Influent 72
32 Analytical Data -SP E- Plant A Lagoon Effluent 72
33 Analytical Data -SP C- Plant A Cooling Tower #2 73
34 Analytical Data -SP D- Plant A Cooling Tower #1 73
35 Analytical Data -SP E- Plant A Well Water 74
36 Analytical Data -SP A- Plant B Intake Water 74
37 Analytical Data -SP B- Plant B Wet Scrubbers 78
38 Analytical Data -SP C- Plant B Thickener Inlet 78
39 Analytical Data -SP D- Plant B Thickener Overflow 7^
40 Analytical Data -SP E- Plant E Cooling Water 79
41 Analytical Data -SP F- Plant B Sewage Plant 80
Effluent
42 Analytical Data -SP G- Plant B Total Plant 80
Discharge
43 Analytical Data -SP A- Plant C Well Water 83
44 Analytical Data -SP B- Plant C Cooling Tower 83
viii
-------
Slowdown
45 Analytical Data -SP C- Plant C Spray Tower Sump 84
46 Analytical Data -SP D- Plant C Thickener Under- 84
flow
47 Analytical Data -SP E- Plant C Sewage Plant 85
Effluent
48 Analytical Data -SP F- Plant C Sludge Lagoon 85
Effluent
49 Analytical Data -SP G- Plant C Thickener Overflow 86
50 Analytical Data -SP A- Plant D Well Water 86
51 Analytical Data -SP B- Plant D Cooling Tower 91
Slowdown
52 Analytical Data -SP C- Plant D Slurry Blend Tank 91
53 Analytical Data -SP E- Plant D Continuous Blow- 92
down
54 Analytical Data -SP C- Plant D Filter Supply 92
Tank
55 Analytical Data -SP F- Plant D Plant Discharge 93
56 Analytical Data -SP A- Plant E Furnace A 96
Scrubber Discharge
57 Analytical Data -SP B- Plant E Furnace B 96
Scrubber Discharge
58 Analytical Data -SP C- Plant E Metals Refining 97
Scrubber Discharge
59 Analytical Data -SP D- Plant E Slag Shotting 97
Wastewater
60 Analytical Data -SP E- Plant E Furnace C 98
Scrubber Discharge
61 Analytical Data -SP F- Plant E Furnace D 98
Scrubber discharge
62 Analytical Data -SP G- Plant E Furnace E 99
Scrubber Discharge
63 Analytical Data -SP H- Plant E Furnace E 99
Scrubber Settling Basin Discharge
ix
-------
64 Analytical Data -SP I- Plant E Slag 100
Concentrator Wastewater
65 Analytical Data -SP J- Plant E Slag 100
Tailings Pond Discharge
66 Analytical Data -SP K- Plant E Lagoon t3 101
Influent
67 Analytical Data -SP L- Plant E Lagoon #3 101
Effluent
68 Analytical Data -SP M- Plant E Intake River 102
Water
69 Analytical Data -SP N- Plant E Cooling Water 102
Discharge
70 Analytical Data -SP O- Plant E Combined Slag 103
Shotting & Cooling Water Discharge
71 Analytical Data -SP P- Plant E Fly Ash 103
Influent to Lagoon
72 Analytical Data -SP Q- Plant E Fly Ash 104
Influent to Lagoon
73 Analytical Data ^SP A- Plant F Intake Water 104
74 Analytical Data -SP B- Plant F Cooling Tower 107
Blowdown
75 Analytical Data -SP C- Plant F Plant Discharge 107
76 Analytical Data -SP A- Plant G Intake City Water no
77 Analytical Data -SP B- Plant G Cooling Tower 110
Blowdown
78 Analytical Data -SP C- Plant G Spray Tower 111
Discharge
79 Analytical Data -SP D- Plant G Settling Basin 111
Effluent
80 Analytical Data -SP E- Plant G Plant Discharge 112
81 Analytical Data -SP F- Plant G Slag Processing 112
Discharge
82 Analytical Data -SP A- Plant H Intake City Water 117
83 Analytical Data -SP B- Plant H Baghouse 117
x
-------
Wastewater Discharge
84 Analytical Data -SP C- Plant H Treated Baghouse 118
Wastewater
85 Analytical Data -SP D- Plant H Settling Lagoon us
Discharges
86 Analytical Data -SP E- Plant H Polishing Lagoon 119
Discharge
87 Analytical Data -SP F- Plant H Plant Discharge 119
88 Analytical Data -SP G- Plant H Plant Well Water 120
89 Analytical Data -SP H- Plant H Cooling Water 120
90 Control and Treatment Technologies by Category 124
91 Industry Category I, Open Electric Furnace with 128
wet Air Pollution Control Devices
92 Industry Category II, Covered Electric Furnace and Other 129
Smelting Operations with Wet Air Pollution Control Devices
93 Industry Category III, Slag Processing 130
94 Treatment Level Costs on Unit of Production 134
Basis
95 Treatment Level Costs on Wastewater Flow Basis 135
96 BPCTCA Effluent Guidelines Treatment Basis 144
97 Best Practicable Control Technology Currently 147
Available Guidelines and Limitations
98 BATEA Effluent Guidelines Treatment Basis 150
99 Best Available Technology Economically 153
Achievable Guidelines and Limitations
100 New Source Performance Standards Basis 156
101 New Source Performance Standards 159
XI
-------
-------
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
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 specific plants
take into account the mix of furnace types and water uses possible in a
single plant which directly influence the quantitative pollutional load.
-------
-------
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 total of the allowable
loads for 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 recirculation 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.
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
categories. The above technologies are generally based upon the use of
'end of pipe' treatment and once-through water usage.
-------
The 30 day average effluent limitations corresponding to the best
practicable control technology currently available are as follows, by
category:
Category
I
Category
II
Category
III
kg/ lb/ kg/
mwhr mwhr mwhr
Suspended Solids.160 .352 .209
Total Chromium .0032 .007 .004
Hex. Chromium .0003 .0007 .0004
Cyanide - - .002
Manganese .032 .070 .042
Phenol - - .004
pH 6-9 6
lb/ kg/ lb/
mwhr kkg pr. ton pr.
.461 1.330 2.659
.009 .026 .053
.0009
.005
.092 .266 .532
.009
9 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 Partial recycle of water, with blowdown treated for removal
of suspended solids and potentially harmful or toxic
pollutants by physical/chemical treatment.
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.
The 30 day average effluent limitations corresponding to the best
available technology economically achievable for Categories I, II and
III are as follows:
-------
Suspended Solids
Total Chromium
Hex. Chromium
Total Cyanide
Manganese
Phenol
PH
Category I
kg/mwhr Ib/mwhr
,012
,0004
,00004
,0039
.026
.0009
.0001
.0086
6-9
Category II Category III
kg/mwhr Ib/mwhr kg/kkg pr. Ib/ton pr.
016
0005
00005
0003
005
0002
6 -
.035
.0012
.0001
.0006
.012
.0005
9
,136
,0027
,027
.271
.0054
.054
6-9
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. 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 30 day average standard of performance for new sources, which
corresponds tc the application of best available demonstrated control
technology, process, operating methods or other alternatives for
Categories I, II and III are as follows:
Category I
kg/mwhr Ib/mwhr
Suspended Solids
Total Chromium
Hex. Chromium
Total Cyanide
Manganese
Phenol
pH
012
0004
00004
0039
6 -
.026
.0009
.0001
.0086
9
Category II Category III
kg/mwhr Ib/mwhr kg/kkg pr. Ib/ton pr.
136 .271
,0027 .0054
,027 .054
6-9
016
0005
00005
0003
005
0002
6 -
.035
.0012
.0001
.0006
.012
.0005
9
-------
-------
SECTION III
INTRODUCTION
The Federal Water Pollution 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
30 4 (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.
-------
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
sutcategories; 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 columbium.
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 (4)
electrolytic deposition. The choice of process is dependent upon the
alloy produced and the availability of furnaces. Ferromanganese is the
principal metallurgical form of manganese. This product contains 15% 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
-------
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 of 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
Silicomanganese
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 furnace 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.U cm (60 in.) W.G., the
power consumption approaches 103S 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 101« 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
-------
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.
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 tc produce ferrochromium, ferrochromesilicon, and 50% and
75% ferrosilicon. Sealed covers are difficult to adapt to 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. Although it can do a good
cleaning job when properly maintained on furnaces producing calcium
carbide, venturi scrubbers do a better job of dust removal for 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 gases 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. Wastewgters 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 JLS£Z 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 1968
Water Use in Manufacturing data as having used 75.7 million liters (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, 1970, 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 Shipments^
Value
Product kk.2 tons kkq tons ($1000^
Ferrcmanganese 757,920 835,463 732,283 807,368 134,456
Silicomanganese 175,285 193,219 156,900 172,988 32,024
Ferrosilicon 643,455 709,287 597,909 659,216 136,238
Silvery Iron 178,143 196,369 188,351 207,664 16,853
Chromium Alloys:
Ferrochromium 280,876 309,613 262,481 289,395 100,667
Other 87,238 96,163 73,968 81,552 25,606
Ferrctitanium 3,048 3,360 2,985 3,291 3,503
Ferrocolumbium 1,143 1,260 1,289 1,421 _ 9,385
Total 2,127,108 2,344,734 2,016,166 2,222,895 458,732
12
-------
Table 1. TYPES, SIZES, AND LOCATIONS OF FERROALLOY PRODUCING PLANTS IN THE UNITED STATES
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.
Air co Alloys Div.
American Potash Co.
Chroriium Mir.ing & Smelting
Co.
Climax Molybdenum Co.
Foote Mineral Co.
Hanna Nickel Smelting Co.
Inter lake, Inc.
Kawecki Berylco 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.
Shieldallcy Corp.
Tennessee Alloys Corp.
Tennessee Metallurgical Co.
Union Carbide Corp.
Woodward Co.
Div. Mead Corp.
L
M
M
S
s
M
S
S
L
M
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
Calvcrt City, Ky.
Charleston, S.C.
Niagara Falls, N.Y.
Theodore, Ala.
Aberdeen, Miss.
Woodstock, Term
Langeloth, Pa.
Cambridge, Ohio
"Graham, W. Va.
Keokuk , Iowa
New Johnsonville,TN
Steubenville, Ohio
Wenatchee, Wash.
Riddle, Oreg.
Beverly, Ohio
Springfield, Oreg.
Easton, Pa.
Selma, Ala.
Kingwcod, W. Va.
Washington, Pa.
Niagara Falls, N.Y.
Palmerton, Pa.
Brilliant, Ohio
Philo, Ohio
Powhatan, Ohio
Tacoma, Wash.
Lister Hill, Ala.
Robssonia, 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
FeCr , FeCrSi ,FeSi , other
FeSi, Silvery Iron
Mn
FeCr, FeCrSi
FeSi, Si
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
No.
Type of furnace Furnaces
Electric
Electric
Electric
Electric
Electrolytic
Electric
Aluminothermic
Electric
Electric
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,
aluminotherraic
Electric
Electric
Electric
Electric
11
2
1
1
5
2
9
5
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
13
-------
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.-
1J7J). Plants using other than blast furnaces thus 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 ($ 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 percent of the
value of shipments in S.I.C. 3313, while numbering 20 out 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 establishments using
more than 75.7 million liters (20 million gal) of water annually are
summarized in Tables 4 thru 9.
14
-------
Table 4. WATER INTAKE, USE, AND DISCHARGE: 1968
No. of Establishments
No. of Employees
Value Added by Manufacture
No. of Establishments Recirculating Water
Liter s_
20.
8,700.
$168.9 X 10*
17
Gallons
Total Intake
Intake Treated Prior to Use
Total Water Discharged
Intake for Process
Intake for Air Conditioning
Intake for Steam Electric Power
Intake for Other Cooling or Condensing 381.5 X 109
Intake for Boiler Feed, Sanitary, etc.
1128.
3406.
1120.
4.
757.
701.
381.
40.
7
5
7
9
4
5
1
X
X
X
X
X
X
X
X
1
1
1
1
1
1
1
1
0«
Q9
09
09
09
298.
900.
296.
1.
200.
185.
100.
10.
2
1
3
3
8
6
X
X
X
X
X
X
X
X
109
10*
109
109
109
109
109
109
Table 5. WATER INTAKE EY WATER USE REGION: 1968
Intake
Region
Delaware and Hudson
Eastern Great Lakes
Ohio River
Tennessee
Southeast
Upper Mississippi
Pacific Northwest
IP9 liters i09__gals_.. No. Establishments
(D)
381.5
684.3
(D)
(D)
(D)
(D)
(D)
100.8
180.8
(D)
(D)
(D)
(D)
(D)
5
7
(D)
(D)
(D)
(D)
(D) Withheld to avoid disclosing data on individual plants.
15
-------
Table 6. WATER INTAKE, USE, AND DISCHARGE: 1968
Value of Shipments $411.4 X 10*
Liters Gallons
Intake from Public Systems 3028. X 10* 800. X 10*
Co. Surface Intake 1119.2 X 10« 295.7 X 10«
Co. Ground Intake 6.4 X 10« 1.7 X 10*
Gross Water Used 1212.3 X 10* 320.3 X 10«
Public Sewer Discharge 1514. X 10* 400. X 10*
Surface Water Discharge 1102.2 X 109 291.2 X 10«
Ground Water Discharge 1892.5 X 10* 500. X 10*
Transferred to other Users 15.5 X 10« 4.1 X 109
Treated before Discharge 199.4 X 10» 52.7 X 109
16
-------
Table 7. INTAKE, USE, AND DISCHARGE BY WATER USE REGION: 1968
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 ether Users
Treated before Discharge
Value of Shipments
$ 97.2
10*
Eastern Great Lakes
Liters Gallons
1892.5 X 109
379.6 X 109
(Z)
379.6 X 109
1514. X 10*
364.5 X 109
378.5 X 10*
15.5 X 109
(Z)
500. X 109
100.3 X 109
(Z)
100.3 X 109
400. X 10*
96.3 X 109
100. X 10*
4.1 X 109
(Z)
$179.8 X 106
Ohio River
Liters 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
378.5 X 10*
677.9 X 109
6.1 X 109
718.8 X 109
(Z)
679.4 X 109
757. X 10*
157.1 X 109
100. X 10*
179.1 X 109
1.6 X 109
189.9 X 109
(Z)
179.5 X 109
200. X 10*
41.5 X 109
(Z) Less than 1.89 million I/year (500,000 gal/year)
17
-------
Table 8. INTAKE WATER TREATMENT PRIOR TO USE: 1968
Treatment Establishments 10* liters 10* gal.
Aeration
Coagulation
Filtration
Softening
Corrosion Control
PH
Other
None
1
4
4
4
4
3
2
13
—
1.9
1.5
.4
1.5
-
-
•"
-
0.5
0.4
0.1
0.5
-
-
—
Table 9. WATER TREATED PRIOR TO DISCHARGE: 1968
Treatment Establishments 109 liters 10?..gal.
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 with the product
groups manufactured by each process.
Submerged-arc furnace process -
Exothermic process -
Electrolytic process -
Vacuum furnace process -
Induction furnace process
Silvery iron
50% Ferrosilicon
65-75% Ferrosilicon
Silicon metal
Silicon-manganese-zirconium
High-carbon (HC) Ferro-
manganese
Silicomanganese
Ferromanganese silicon
Charge chrome
HC ferrochrcmium
Ferrochrome silicon
Calcium carbide
Low-carbon (LC) ferro-
chromium
LC ferromanganese
Medium-carbon (MC) ferro-
manganese
Chromium metal
Titanium, Vanadium and
Columbium Alloys
Chromium metal
Manganese metal
LC ferrochromium
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 purchase of
ores are their physical characteristics, ease of reduction, and
analytical specifications necessary to meet customer requirements.
19
-------
invested in the ores held in storage may 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 or 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 furnace charges in order to
produce a specified ferroalloy. Normally, raw materials are conveyed to
a mix house where they are weighed and blended. After the batch has
been assempled, it is moved by conveyors, buckets, skip hoist, 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 the production
of alloys is basically the same throughout the industry; but they differ
in electrical connections, arrangements of electrodes, and shape and
size of the hearth. The three carton electrodes are arranged in a delta
formation, with the tips submerged .9-1.5 m (3-5 ft.) into the 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 transferred to
the charge and partly prereduces the ore as it passes downward into the
center of the furnace. Because of the passage of the 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 the reaction zone
during the reduction process will flow without hindrance into a hood
built above the furnace. The gases burn on the surface of the 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 the hot 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 the top of the
furnace crucible. In such furnaces raw materials are used that 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 for cooling
the steel shell. The bottom interior of the steel shell is lined with
two or more layers of carbon blocks and tightly sealed with a carbon
compound packed between the joints. The interior walls of the furnace
shell are lined with refractory or carbon 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 shows 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 hearth and
between electrodes. Final reduction of the oxidic ores occurs in the
lower portion of the furnace.
Submerged-arc furnaces generally operate continuously except for 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 (4.U Ib) of
carbcn 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 ferrochrcmium, this may entail
rearrangement of electrode spacing and different power loads and voltage
requirements. It may also reduce the efficiency of the furnace
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
-ELECTRODES
REACTION
GASES
CHARGE
MATERIAL
MOLTEN FERROALLOY
CARBON HEARTH
CRUCIBLE
CARBON
REFRACTORY
LINING
24
-------
U1
Figure 3.
CROSS SECTION OF OPEN FURNACE
©
TAPPING FLOOR-
CRANE FOR PASTEi
CASING HANDLING
i i i i i i i i i i i i i i i i i i i i i i i i . n 1 I I 1 I I I I I
_
OFFTAKE
SUPERSTRUCTURE
OPERATING
<£ FCE (IFI ECTRICAL '"
GROUP '"
-------
The molten alloy from the carbon reduction of the ore accumulates 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.
FERRCSILICON 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 oxide, calcium oxide,
and phosphorous. The reducing agent usually used is coke; other
reducing agents are coal, petroleum coke, and charcoal. The reducing
agent should have minimum ash and phosphorous content. 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 50% ferrosilicon is typically
as shown in Table 10.
Table 10. MATERIAL BALANCE FOR 50% FERROSILICON
(% of material charged)
Input
Quartzite
Coke
Steel Shavings
Electrode Mass
Output
Alloy
Volatilized
41.8
58.2
100.0
The charge materials for the production of silicon metal should 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 from 5Q% FeSi
to silicon metal.
Ferrosilicon is usually smelted in Biphase 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 yards, transported by
conveyors to the proportioning floor, and distributed among the furnace
hoppers. From the hoppers the charge is fed into the furnace charge
holes. During the production of ferrosilicon, the furnace operates
continuously and the metal is tapped as it accumulates. Six to eight
tappings per shift are made. After tapping is finished as indicated by
the appearance of flame at the tap hole, plugs 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
ferrosiliccn are used to produce ferromanganese. When ferromanganese is
produced from its ores, iron, manganese, silicon, phosphorous, and
sulfur are reduced and complex iron and manganese 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 either the 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 the 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 the ore can be
reduced; the reduced phosphorous partially evaporates and escapes from
the furnace while 60% of the total phosphorous in the charge passes into
the alloy. Of the total sulfur introduced in the charge 1% passes into
the alloy, 40-45% passes into the slag, and 55% 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
Coke
Limestone
Electrode mass
64.7
18.0
16.8
0.5
100.0
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, 8-1055 escapes, and 30-329! passes into the slag; 7058 of
the manganese in the slag is extracted when silicomanganese 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, 30.955 pass into
the alloy, 29.555 pass into the slag, and 39.6% escapes as gas and dust.
The gas contains 65-7055 CO.
Table 12. HC FERROMANGANESE CHARGE MATERIALS -
SELF-FLUXING METHOD
(55 by weight)
Manganese ore (4855 Mn)
Lime
Coke
Electrode mass
74.8
a. 6
20.0
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 FERROMANGANESE CHARGE
(% by weight)
Manganese ore 43.6
Lime 24.3
Silicomanganese (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) .
SILICCMANGANESE PROEUCTION
Silicomanganese is also produced in electric submerged-arc furnaces.
The charge is continuously loaded and slag and metal are tapped 3 to 4
times during an 8-hour shift. Silicomanganese may be smelted from
manganese ore, from self-*fluxing slag from ferromanganese production, or
from a combination of both.
A typical charge to produce Silicomanganese is shown in Table 14.
Table 14. SILICOMANGANESE CHARGE MATERIALS
(X by weight)
Manganese Slag 27.9
Manganese Ore 27.9
Coal or coke 17.3
Lime 15.6
Recycle Scrap 3.1.3
100.0
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.
FERRCCHROMIUM PRODUCTION
Ferrcchromium 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 FerrQchromiujn Smej.ti.ng
In the production of HC ferrochromium, the chromium and 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 loadings than are used for most other 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 FERRCCHRCMIUM
(% 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
HC FeCr
% in total charge
Element to alloy to_sl.ac[ loss
Chromium 90 6 U
Iron 98 2 -
Silicon 15 80 5
Phosphorous 60 20 20
Sulfur 10 30 60
Ferrochromes ilicon SineIt ing
Ferrochromesilicon is generally produced by the direct method. 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. The exothermic process
is generally used to produce higher grade alloys with low carbon
content. Low-carbon and medium-carbon ferrochroirium and low-carbon or
medium-carbon ferromanganese are produced by silicon reduction. A flow
diagram of a typical silicon reduction process for manufacturing LC
ferrcchromium is shown in Figure 4. 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
-------
Figure 4,
FLOW SHEET LC FERROCHROMIUM
LECTRODES
Cr ORE
QUART-
ZITE
ELECTRODES
COKE
WOOD
CHIPS
Cr
ORE
FeCrSi
SUBMERGED-ARC
FURNACE
LIME
Cr ORE/LIME MELT
OPEN-ARC
FURNACE
±26%Cr203
REACTION LADLE
REACTION LADLE
THROW-AWAY
SLAG
SECONDARY
THROW AWAY
SLAG
PRODUCT
LC FeCr
i 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 ladle 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. LC and MC ferromanganese are
produced by a similar practice using 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 the emissions from
submerged-arc furnaces.
ALUMINUM REDUCTION
Aluminum reduction is used to produce chromium metal, ferrotitanium,
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 the production of
ferromolybdenum and ferrotungsten. Usually such alloys are produced by
exothermic reactions initiated by an external heat source and carried
out in open vessels. The high-temperature reaction of 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 which 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) which 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 cf the alloy. Such a
furnace is shown in Figure 5.
The process is based on the oxidation of HC ferrochromium by the oxygen
in silica or chrome oxide, with which it has been mixed after crushing.
The CO gas resulting from the reaction is pumped out of the furnace in
order to maintain a high vacuum and to facilitate the ferrochromium
decarburization. Heat is supplied to the furnace by electric resistance
elements.
Induction furnaces, either low-frequency or high-frequency, are used to
produce small tonnages of a few specialty alloys through remelting of
the required constituents. Such a furnace is shown in Figure 6.
PRODUCT SIZING AND HANDLING
Ferroalloys are marketed in a bread range 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, the ferroalloy
product size is important.
Molten ferroalloys from the submerged-arc furnaces are generally tapped
into refractory-lined ladles and then into molds or chills for cooling.
The chills are low, flat iron or steel pans that remove heat 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 the broken product.
Large jaw crushers, rolls, mills, cr grinders for reducing the product
size and rotating and vibrating screens are used for this purpose.
Conveyors and elevators move the product between the crushing and
screening operations. Storage bins are provided to hold the finished or
intermediate products.
34
-------
Figure 5.
VACUUM FURNACE FOR FERROALLOY PRODUCTION
UJ
Cn
TO VACUUM
PUMPING SYSTEM
TO INERT
GAS COOLING
ELECTRICAL
LEADS
Ttr itr
7 /' /V/f//
^
\I^^r=^
I
l|T Vfr itr
/v y^/vy.
1 T
.TtT
' /y /
TtT TI TJT
' /i// /]//>
-------
Figure 6.
INDUCTION FURNACE DIAGRAM
FURNACE
CRUCIBLE
U)
01
FURNACE
OPERATORS PANEL
CHARGING
PLATFORM
ELECTRICAL LEADS
ELECTRICAL SUBSTATION
-------
EMISSIONS FROM SUBMERGED-ARC FURNACES
Since the quantity and composition of the emissions from ferroalloy
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 submerged-arc furnace
utilizes carbon reduction of metallics in the oxide ores, and
continuously produces large quantities of 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 sized constituents of the mix.
In an open furnace, all CO and other combustibles in the furnace 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 the furnace the
fume size is generally below two microns (u) and ranges from 0.1 to l.Ou
with a geometric mean of 0.3 to 0.6 depending upon the ferroalloy
produced. In some cases, agglomeration does occur, and the 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 the 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 (SiOj2) (Ref. 5) . Some tars and
carbon are present arising from the coal, coke, or wood chips used in
the charge. Ferrochrome-silicon furnaces produce an Si02! 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 Si02 and manganese oxides. The
emissions from chromium furnaces contain SiO£, MgO and some iron and
chromium oxides.
Chemical analysis of the fumes indicate their compositicn 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
Ref. 5
U)
Furnace product
Furnace type
Fume shape
Fume size char-
acteristics ,
microns
Maximum
Most particles
X-ray diffraction
trace constituents
Chemical
Analysis, %
S102
FeO
MgO
CaO
MnO
A1203
LOI
TCr as Cr203
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
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
fumes were- primarily amorphous
Mn304
MnO
Quartz
15.68
6.75
1.12
-
31.35
5.55
23.25
-
-
-
- 0.47
-
-
—
Quartz
SiMn
Spinel
24.60
4.60
3.78
1 .58
31. si
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 those from the
submerged-arc furnace are emitted from the reaction ladle or furnace
while the reducing agent is being charged during alumino- or
silicothermic reduction. This emission is due to strong agitation of
the molten bath and the rapid temperature rise. 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 from 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 (20-40 Ibs) of particulates per ton of ferroalloys produced.
The total tonnage of ferroalloys made by the exothermic process amounts
to 10 to 15 percent of the total ferroalloys production in the United
States.
OPERATING VARIABLES AFFECTING EMISSIONS
Because of the complexity of the heavy mechanical and electrical
equipment associated with a modern submerged-arc furnace, close
supervision and maintenance are required to prevent frequent furnace
shutdowns. The furnaces are designed to operate continuously to
maintain satisfactory metallurgical and thermal equilibria.
Normal furnace shutdowns on an annual basis may average three to ten
percent of the operating time and are caused by a wide variety of
situations. These can be electrode installations, maintenance, repair
of water leaks at electrode contact plates, mix chute failures, furnace
hood or cover failures, taphole problems, electrical 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 in duration and usually are not more than several
hours. Following such interruptions, the furnace 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 a 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 furnace, 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 furnace 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 to 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, (4) 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 Si02 increases, therefore, a
silicon-metal furnace emits substantially more S±O2 fumes than an
equivalent-size 50% ferrosilicon 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 hot furnace crucible, violent gas
eruptions can occur. This is best exemplified by the manganese ore-lime
melt furnace where momentary gas flow 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 smooth 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,, ends J ions 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 generation remaining almost constant,
the emission concentration and weight per hour of particulates can vary
by a factor of 5 to 1. Operating with insufficient electrode immersion
promotes increased emissions.
Higher voltage operation for a given furnace will promote higher
electrode positions and increase the concentration and amount of
emissions.
On seme operations, especially silicon metal production, the charge must
be stoked to break up crusts, cover areas of gas blows, and permit the
flow of reaction gases. Therefore, both furnace operations and
emissions can be a function of how well and how often the furnace is
stoked.
Maintenance practices significantly affect emissions on covered furnaces
because accumulation of material under the cover and in gas ducts
reduces the gas withdrawal capacity of the exhaust system. Plugging of
gas passages in the control equipment results in reduced efficiency of
gas cleaning.
PRODUCTION AND EMISSION DATA FOR FERROALLOY FURNACES
The data in Table 18 summarize pertinent data as to
emission factors fcr submerged-arc furnaces (Ref. 32).
production and
The data of Table 19 summarize the types of air pollution control
devices used in various ferroalloy furnaces producing specific products
in the United States.
Some comparisons of the off-gas volume from
controlled open furnaces are shown in Table 20.
Table 20. ILLUSTRATIVE OFF-GAS VOLUMES FROM OPEN
AND CLOSED FURNACES - REF 32.
covered furnaces and
Product
Closed Furnaces Open Furnaces
Nm3/min-mw scfm/mw Nml/minrmw scfm/mw
FeMn
FeSi (65-75%)
SiMn
FeSi (50%)
6.16
5.88
5.60
5. OH
220
210
200
180
370
521
204
258
13,200
18,600
7,300
9,200
U1
-------
Table 18. PRODUCTION AND EMISSION DATA FOR FERROALLOY FURNACES
Product
Silvery Iron
50 % FeSi
65-75% FeSi
Si Metal
SMZ
Mn ore/lime melt
CaSi
HCFeMn
SiMn
FeMnSi
FeCrSi
Chg Cr
HCFeCr
Cr ore/lime melt
Uncontrolled
kg/kkg alloy 1
58
223
458
500-1000 1
Parti cul ate
bs/ton alloy
116
446
915
000-2000
No data No data
67
672
168
110
158
416
168
168
6
133
1343
335
219
315
831
335
335
11
Emissions
kg/mwhr Ib/mwhr
20.4 45
40.4 89
47.2 104
33-65 72-144
No data ffo data
37.7 83
51.7 114
28.1 62
22.7 50
26.3 58
50.8 112
28.1 62
28.1 62
4.1 9
Electric
mwhr/kkg alloy
2.9
5.5
9.7
15.4
9.7
1.8
13.0
2.6
4.9
6.0
8.2
4.6
4.6
1.3
Energy
mwhr/ton
2.6
5.0
8.8
14.0
8.8
1.6
11.8
2.4
4.4
5.4
7.4
4.2
4.2
1.2
Ratio of Charge
alloy to Product Weight
1.8
2.5
4.5
4.9
4.5
3.5
3.9
3.0
3.1
4.3
3.4
4.0
4.0
1.2
-------
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
U)
Control device
Wet scrubbers
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 can be realized only
by categorizing the industry into the minimum number of groups for which
separate effluent limitation guidelines and new sources performance
standards must be developed. The categorization here is believed to be
that rr.ininrnm, i.e., the least number of groups having significantly
different water pollution potentials and treatment problems.
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
In developing the above categorization, the following factors were
considered as possibly providing some basis 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
4. 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 Pollution Control Equipment
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 such as scrubbers. Since the
only water pollution potential from an electric furnace, which 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 'wet* furnaces, would be excessively
permissive to the 'dry' ones, and vice versa. For this reason, the
categorization selected is partially based upon the 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 precipitators 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.
Production Processes
The various production processes vary markedly in their ability 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 (when divided by 3) is of the same order of
magnitude as that of covered electric furnaces (per mwhr), 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 the residual metal values left in
the slag after smelting, and helps reduce the solid waste load somewhat
at these plants. This process is intrinsically different from the other
production processes, inasmuch as it is inherently 'wet1, and therefore
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 dc not use such a
process and the magnitude of the potential wasteload is substantial.
Furnace Types
The types of smelting furnaces were found to provide a basis for
categorization in conjunction with consideration of water uses and other
factors. The differences between open and covered or sealed electric
smelting furnaces are significant insofar as they relate to the raw
waste loads and the pollutants present and air pollution control
technologies available for use. The off-gas volumes from the two types
of furnaces may vary by a factor of 50 between the 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 the differences in the
off-gas volumes. Person's (5) published data show a difference in water
circulation with venturi scrubbers of a factor of 24 between open and
covered furnaces. The final volume of 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 than furnace type. The
recirculation of water at the venturi scrubbers on open furnaces must be
regarded as a part of the waste water treatment methods 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 known 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 charge for HC
ferromanganese consists of manganese ore, coke, and limestone, while 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 the covered furnace
feed materials may require pretreatment. There are, of course.
U7
-------
substantial differences in the charge into electric furnaces and the
feed to slag processing operations.
Product Produced
Categorization by product would result in a large number of guidelines
and standards, since the number cf products which can be produced in a
furnace is fairly large, and many products can 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 or cut back the production of these
products and converted to other, more profitable product 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)/mwhr 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 be 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 a separate categorization.
Although elder 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 of the furnace has changed
little over many years, although newer furnaces may utilize somewhat
more water for cooling.
Waste Water Constituents
The waste water constituents provide a collateral, but not independent
basis for categorization. Suspended solids are the largest single
constituent of the waste waters and appear in effluent from all of the
various processes. Suspended solids obviously result from the use of
wet devices to remove particulates from smelting off-gases. Chromium,
as another example, is in the effluents from chromium smelting
48
-------
operations, and chromium slag concentrating operations. Cyanides are
generated in significant concentrations only in covered furnaces. This
distinction appears in the differentiation between open 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 that the waste
constituents do. The treatment methods consist principally of
coagulation and sedimentation, neutralization and precipitation,
reduction of chromium, oxidation of cyanides and phenol, and
recirculation and re-use. All of these methods, except for cyanide
oxidation, are applicable to one extent or another in all of the various
types of production operations. Cyanide is found in significant
quantities only in scrubber water 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 with fabric filter
systems, and this method has been commonly used in the industry for this
type furnace. Covered or sealed furnaces, however, in this country are
only 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.
Water Uses
Water uses were judged to be a significant basis for categorization.
The categorization differentiates between processes on the basis of
water use for wet air pollution control devices and for slag processing.
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 kwhr 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.
-------
-------
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 as follows:
1. 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
2. Sanitary Uses, Boiler Feed, Air Conditioning, etc.
3. Slag Processing Uses
PUBLISHED DATA SOURCE CHARACTERIZATIONS
A total of 2,329,630 kkgs (2,568,500 tons) of ferroalloys were produced
in 1967, using 11,206 million kw-hrs. of electric energy according to
the 1967 Census of Manufactures Of the total energy used, 3,354 million
kw-hrs. were generated by ferroalloy plants. Assuming miscellaneous
losses and other uses of 15 percent, an average use of 4,089 kw-hrs. per
kkg (3,709 kw-hrs. per ton of alloy in terms of furnace power is
indicated.
Total water intake for S.I.C. 3313 plants was 1128.7 X 10« liters (298.2
X 109 gals.) per year according to the 1S67 Census of Manufactures while
gross water use was 1212.3 X 109 liters"(320.3 X 10* gals.). Intake for
cooling was 381.5 X 10« liters (100.8 X J0« gals.). Assuming that all
water recirculation and reuse was for cooling, cooling water use was
465.2 X 109 liters (122.9 X 10« gals.) Cooling water use of 199,679
liters per kkg (47,849 gal. per short ton) of alloy, or 48.8 liters
(12.9 gals.) per kw-hrs. of furnace power is indicated.
The 1967 Census of Manufactures indicates a water use of 701.4 X 109
liters (185.3 X 109 gals.J^of water in generating the 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 other uses at 15
percent, a water use of 245.6 liters (64.9 gals.) per kw-hr. of furnace
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
have been 825 X 106 liters (218 X 106 gals.) per year; air conditioning
51
-------
use was 757 X 10* liters (200 X 10* 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 gpm) for each of three furnaces
producing FeCrSi, SiMn, and HC FeCr and 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% operating load, the indicated water use is
620.7 liters (164 gals.) per mw-hr. of furnace power.
According to Retelsdorf, et.al. (6) an electrostatic precipitator
installed on a 20 mw ferrochromesilicon 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 95% operating time and 75%
operating load. About 10-15 % of the water used is discharged from the
bottom of the spray tower, the remainder being evaporated into the gas
stream. These data indicate about 556.4 liters (147 gals.) of 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.
Assuming that 556 liters (147 gals.) of water per mw-hr. of furnace
power is evaporated in the gas 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:
High energy scrubbers (open furnace) = 19,682 1/mw-hr (5200 gal/mw-hr)
High energy scrubbers (covered furnace) = 609 1/mw-hr (161 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:
52
-------
Acidity
Alkalinity
Aluminum
Ammonia
Barium
B. O. D.
Calcium
Chromates
Chromium
Columbium
Cyanide
Dissolved Solids
Iron
Magnesium
Manganese
Molybdenum
PH
Phosphates
Potassium
Radioactivity
Silica
Sulfates
Suspended Solids
Temperature
Titanium
Vanadium
Zirconium
WASTE CHARACTERIZATIONS FROM DISCHARGE PERMIT DATA
Waste constituents/parameters listed
applications for the plants in S.I.C.
Algicides
Aluminum
Ammonia
Bar ium
Boron
Calcium
Chloride
Chromium
Color
copper
Fluorides
Hardness
Iron
Magnesium
Manganese
Nickel
Nitrate
Oil and Grease
Organic N
Phosphorous
as present in discharge
3313 are as follows:
Sodium
Solids
Sulfate
Sulfide
Sulfite
Surfactants
Titanium
Turbidity
Zinc
permit
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 they 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.
WASTE CHARACTERIZATION - OPEN ELECTRIC FURNACES WITH WET
CONTROL DEVICES
AIR POLLUTION
The data from Plant D provides raw waste loads for open submerged arc
furnaces in which the off-gases are scrubbed with steam/hot water
scrubbers as shown in Table 21.
53
-------
Table 21. RAW WASTE LOADS-OPEN CHROMIUM ALLOY AND
FERROSILICON FURNACES WITH STEAM/HOT WATER SCRUBBERS
Constituent
Suspended Solids
Manganese
Cr, total
Cr , hex .
Flow
kg/mwhr
8.2 '
.005
.003
.002
1/mwhr
2,691
Ibs/mwhr
18.1
0.010
0.007
O.OOU
gals/mwhr
711
The data from Plant E provide an additional raw waste load for an open
electric furnace using a venturi scrubber, as shown in Table 22.
Table 22. RAW WASTE LOAD - HIGH ENERGY SCRUBBER
ON OPEN ELECTRIC FURNACE
Constituent
Suspended Solids
Manganese
Chroirium (Total)
Flow
kg/mwhr
23. 74
10.06
0.002
1/mwhr
6,382
Ib/mwhr
52.29
22.15
0.005
gals/mwhr
1,686
The data from Plant G providing raw waste loads for open submerged arc
furnaces in which the off-gases are conditioned in a spray tower
preceding an electrostatic precipitator are shown in Table 23.
-------
Table 23. RAW WASTE LOADS-OPEN CHROMIUM ALLOY
FURNACES WITH ELECTROSTATIC PRECIPITATORS
Constituent
kq/mwhr Ibs/mwhr
Suspended Solids
Manganese
Chromium, total
Flow
.289
.0012
.0016
1/mwhr
84.0
0.636
0.0026
0.0036
qals/mwhr
22.2
Although the data as given in Table 23 for water flow agrees quite well
with that predicted (84.0 vs 79.5 1/mwhr)(22.2 vs 21 gal/mwhr), 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 frcm the high energy
scrubber does not take into account recirculation of the 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.
55
-------
Table 24. RAW WASTE LOADS FOR COVERED FURNACES
WITH DISINTEGRATOR SCRUBBERS
Suspended Solids
Cyanides
Flow
Product kg/mwhr Ibs/mwhr kq/mwhr Ibs/mwhr 1/mwhr qa1/mwhr
SiMnZr
75% FeSi
50% FeSi
75% FeSi
20.1
39.2
5.1
6.8
44.3
86.3
11.3
15.0
.0338
-
.0001
.0139
.0745
-
.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 the 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 been 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 for 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
-------
Table 25. RAW WASTE LOADS-SEALED SILICOMANGANESE
FURNACE WITH DISINTEGFATOF SCFUEEER
Constituent
kq/mwhr
Ib/mwhr
Suspended solids
Phenol
Cyanide, total
Cyanide, free
Chromium, total
Manganese
Flew
16.6
.009
.044
.011
.0004
4.858
l/mwhr_
10,863
36.6
.019
.098
.024
0.001
10.70
gals/mwhr
2,870
The data from Plant E also provide data on scrubber raw waste water
loads from covered furnaces equipped with high energy and disintegrator
scrubbers.
Table 26. RAW WASTE LCAD-COVEFED FUFNACES WITH
SCRUEEEFS
Constituent
Susp. Solids
Phenol
Cyanide (Total)
Manganese
Chromium (Total)
Flew
kq/mwhr Ibs/mwhr
4.01
0.002
0.007
0.016
0.002
8.83
0.004
0.015
0.034
0.004
1/mwhr qals/mwhr
9,746 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.
57
-------
Table 27. RAW WASTE LCADS-ALUMINOTHERMIC SMELTING
WITH COMBINATION WET SCRUBBERS AND BAGHOUSE
Constituent kq/kkq Ib/ton
Suspended Solids
Phenol
Cyanide (Total)
Cyanide (Free)
Manganese
Chroir.ium (Total)
Chromium (Hex.)
Flow
3.6
0
0
0
0.0005
2.98
0.95
i/Ma
26,332
7.1
0
0
0
0.001
5.95
1.90
qals/tcn
6,310
Since open furnaces produce greater volumes of gas than do covered
furnaces, and since water usage in wet scrubbers is generally a function
of gas volume treated, it was expected that open furnace scrubbers would
have higher water usages than covered furnace scrubbers. Contrary to
expectations, the covered furnaces which were surveyed had water uses
higher than those of open furnaces using high energy scrubbers. This
may be because water use in disintegrator scrubbers is higher, for a
particular gas volume, than the water use in high energy scrubbers.
Most of the covered furnaces surveyed used disintegrator, rather than
high energy scrubbers. However, one furnace at Plant E was equipped
with a high energy scrubber, and the water use on that equalled 9572
1/mwhr (2529 gal/mwhr), so it would seem that this explanation may not
always be valid.
WASTE CHARACTERIZATION - SLAG PROCESSING
The data from Plant E provides information on the raw waste loads from
slag processing operations. That from slag concentrating is shown in
Table 28.
58
-------
Table 28. RAW WASTE LOADS-SLAG CONCENTRATION PROCESS
Constituent kg/kkg It/ton
Suspended Solids
Manganese
Chromium, (Total)
Flow
46.0
.245
.109
1/kkg
48,259
91.9
.489
.217
gals/ton
12,750
No raw waste load can te calculated directly for the 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/ton 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 lead of 3.87 Ib/ton.
59
-------
-------
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 for 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 Table 29.
Table 29. POLLUTANT PARAMETERS FOR INDUSTRY CATEGORIES
Parameters Industry Category
_I_ II III
Suspended solids
pH
Total Chromium
Hexavalent Chromium
Total Cyanide
Manganese
Phenol
X
X
X
X
-
X
^
X
X
X
X
X
X
X
X
X
X
-
-
X
™"
Although effluent flow volumes are not specified in the recommended
guidelines, its measurement and control is implicit in attaining the
pollutant effluent loads specified. Flow, of course, is a basic
parameter in that its magnitude indicates the degree of 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.
Oil is not here considered as a parameter because it was found in lower
concentrations in the raw waste than were allowable by the proposed
guidelines. Additionally, oil is not associated with the process
itself, but only appears as leaks from machinery, etc. At the levels
detectable by the NPDES test methods, oil would be visible as a light
sheen, and the plant would realize that there was an oil leakage
somewhere.
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. The pH determination in conjunction with
metals determinations indicates that excessive free acidity or
61
-------
alkalinity has been neutralized after chromate reduction and
precipitation, or cyanide destruction.
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 harmful 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 very small quantities may be
present in that from open furnaces. It would seem that phenols are
oxidized in open furnaces, but not in the reducing atmosphere of covered
furnaces. Because they are evidently oxidized in open furnaces, phenols
are not considered as a pollutant parameter for Category I.
Phosphate was originally considered as a pollutant parameter because it
was present in some quantity in the wastewaters at a few plants.
Examination of the data base for this pollutant, however, convinces us
that it is generally present in fairly low concentrations in the raw
waste, and drops out during treatment (even the rudimentary treatment
given at some plants) to levels allowable by the proposed guidelines.
Therefore, phosphate was dropped as a parameter after consideration of
the costs of monitoring for a pollutant which will probably never exceed
the guidelines.
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 and sulfates appear
in effluents, 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 they are controlled if suspended solids
concentrations are controlled.
Environmental Impact of Pollutant Parameters
The following is a discussion of the environmental impacts of the
pollutant parameters selected for regulation:
62
-------
Suspended solids
Suspended solids include both organic and inorganic materials. The
inorganic components include sand, silt, and clay. The organic fraction
includes such materials as grease, oil, tar, animal and vegetable fats,
various fibers, sawdust, hair, and various materials from sewers. These
solids may settle out rapidly and bottom deposits are often a mixture of
both organic and inorganic solids. They adversely affect fisheries by
covering the bottom of the stream or lake with a blanket of material
that destroys the fish-food bottom fauna or the spawning ground of fish.
In raw water sources for domestic use, state and regional agencies
generally specify that suspended solids in streams shall not be present
in sufficient concentration to be objectionable or to interfere with
normal treatment processes. Suspended solids in water may interfere
with many industrial processes, and cause foaming in boilers, or
encrustations en equipment exposed to water, especially as the
temperature rises. Suspended solids are undesirable in water for
textile industries; paper and pulp; beverages; dairy products;
laundries; dyeing; photography; cooling systems, and power plants.
Suspended particles also serve as a transport mechanism for pesticides
and other substances which are readily sorbed into or onto clay
particles.
Solids may be suspended in water for a time, and then settle to the bed
of the stream or lake. These settleable solids discharged with man's
wastes may be inert, slowly biodegradable materials, or rapidly
decomposable substances. While in suspension, they increase the
turbidity of the water, reduce light penetration and impair the
photosynthetic activity of aquatic plants.
Solids in suspension are aesthetically displeasing. When they settle to
form sludge deposits on the stream or lake bed, they are often much more
damaging to the life in water, and they retain the capacity to displease
the senses. Solids, when transformed to sludge deposits, may do a
variety of damaging things, including blanketing the stream or lake bed
and thereby destroying the living spaces for those benthic organisms
that would otherwise occupy the habitat.
Turbidity is principally a measure of the light absorbing properties of
suspended solids. It is frequently used as a substitute method of
quickly estimating the total suspended solids when the concentration is
relatively low,
EH
The term pH is a logarithmic expression of the concentration of hydrogen
ions. At a pH of 7, the hydrogen and hydroxyl ion concentrations are
essentially equal and the water is neutral. Lower pH values indicate
acidity while higher values indicate alkalinity. The relationship
63
-------
between pH and acidity or alkalinity is not necessarily linear or
direct.
Waters with a pH below 6.0 are corrosive to water works structures,
distribution lines, and household plumbing fixtures and can thus add
such constituents to drinking water as iron, copper, zinc, cadmium and
lead. The hydrogen ion concentration can affect the "taste" of the
water. At a low pH water tastes "sour". The bactericidal effect of
chlorine is weakened as the pH increases, and it is advantageous to keep
the pH close to 7. This is very significant for providing safe drinking
water.
Extremes of pH or rapid pH changes can exert stress conditions or kill
aquatic life outright. Dead fishr associated algal blooms, and foul
stenches are aesthetic liabilities of any waterway. Even moderate
changes from "acceptable" criteria limits of pH are deleterious to some
species. The relative toxicity to aguatic life of many materials is
increased by changes in the water pH. Metallocyanide complexes can
increase a thousand-fold in toxicity with a drop of 1.5 pH units. The
availability of many nutrient substances varies with the alkalinity and
acidity.
The lacrimal fluid of the human eye has a pH of approximately 7.0 and a
deviation of 0.1 pH unit from the norm may result in eye irritation for
the swimmer. Appreciable irritation will cause severe pain,
Phenols
Many phenolic compounds are more toxic than pure phenol; their toxicity
varies with the combinations and general nature of total wastes. The
effect of combinations of different phenolic compounds is cumulative.
Phenols and phenolic compounds are both acutely and chronically toxic to
fish and other aquatic animals. Also, chlorophenols produce an
unpleasant taste in fish flesh that destroys their recreational and
commercial value.
It is necessary to limit phenolic compounds in raw water used for
drinking water supplies, as conventional treatment methods used by water
supply facilities do not remove phenols. The ingestion of concentrated
solutions of phenols will result in severe pain, renal irritation, shock
and possibly death.
Phenols also reduce the utility of water for certain industrial uses,
notably food and beverage processing, where it creates unpleasant tastes
and odors in the product.
-------
Cyanide
Cyanides in water derive their toxicity primarily from undissolved
hydrogen cyanide (HCN) rather than from the cyanide ion (CN-). HCN
dissociates in water into H* and CN~ in a pH-dependent reaction. At a
pH of 7 or below, less than 1 percent of the cyanide is present as CN~;
at a pH of 8, 6.7 percent; at a pH of 9, 42 percent; and at a pH of 10,
87 percent of the cyanide is dissociated. The toxicity of cyanides is
also increased by increases in temperature and reductions in oxygen
tensions. A temperature rise of 10*C produced a two- to threefold
increase in the rate of the lethal action of cyanide.
Cyanide has been shown to be poisonous to humans, and amounts over 18
ppm can have adverse effects, A single dose of about 50-60 mg is
reported to be fatal.
Trout and other aquatic organisms are extremely sensitive to cyanide.
Amounts as small as .1 part per million can kill them. Certain metals,
such as nickel, may complex with cyanide to reduce lethality especially
at higher pH values, but zinc and cadmium cyanide complexes are
exceedingly toxic.
When fish are poisoned by cyanide, the gills become considerably
brighter in color than those of normal fish, owing to the inhibition by
cyanide of the oxidase responsible for oxygen transfer from the blood to
the tissues.
Chromium
Chromium, in its various valence states, is hazardous tc man. It can
produce lung tumors when inhaled and induces skin sensitizations. Large
doses of chromates have corrosive effects on the intestinal tract and
can cause inflammation of the kidneys. Levels of chrcmate ions that
have no effect on man appear to be so low as to prohibit determination
to date.
The toxicity of chromium salts toward aquatic life varies widely with
the species, temperature, pH, valence of the chromium, and synergistic
or antagonistic effects, especially that of hardness. Fish are
relatively tolerant of chromium salts, but fish food organisms and other
lower forms of aquatic life are extremely sensitive, chromium also
inhibits the growth of algae.
In some agricultural crops, chromium can cause reduced growth or death
of the crop. Adverse effects of low concentrations of chromium on corn,
tobacco and sugar beets have been documented.
Manganese
65
-------
The presence of manganese may interfere with water usage, since
manganese stains materials, especially when the pH is raised as in
laundering, scouring, or other washing operations. These stains, if not
masked by iron, may be dirty brown, gray or black in color and usually
occur in spots and streaks. Waters containing manganous bicarbonate
cannot be used in the textile industries, in dyeing, tanning,
laundering, or in hosts of other industrial uses. In the pulp and paper
industry, waters containing above 0.05 ppm manganese cannot be tolerated
except for low-grade products. Very small amounts of manganese—0.2 to
0.3 ppm—may form heavy encrustations in piping, while even smaller
amounts may form noticeable black deposits.
66
-------
SECTION VII
CONTROL AND TREATMENT TECHNOLOGY
The water pollution control and treatment technology used in the
ferroalloy industry has generally been sedimentation in lagoons, some of
which are very large. The 8 plants which were surveyed in the course of
the present study cover the full range of processes used in the industry
and the various levels of control and treatment technology.
By far the most serious pollution problem to the industry has been that
of air pollution. Air pollution abatement has been a major concern of
the industry and has involved most of the expenditures for pollution
control. Air pollution control systems installed, being built, or
planned are generally capable of meeting existing state regulations; in
cases where controls have been 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 30 in terms of the industry
categorization given previously.
Table 30. CHARACTERISTICS OF SURVEYED PLANTS
Plant Category Processes and Water Uses and Air Controls
A Baghouses being built, recirculated
cooling water
B II Disintegrator scrubbers, once-through
cooling water use
C II Sealed furnace, disintegrator scrubbers,
recirculated cooling water and scrubber water
D I Steam/hot water scrubbers, recirculation of
cooling and scrubber water
E I,II,III Disintegrator scrubbers, venturi scrubbers,
once-through water use, slag processing
F Baghouse/no air controls, recirculated
cooling water
G I,III Electrostatic precipitators with water
sprays, recirculated cooling water, slag processing
H II 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:
67
-------
Suspended Solids: Water recirculation, lagoons, clarifier-flocculators,
sand filters
pH: Neutralization
Chromium: Hexavalent chromium reduction, precipitation, sedimentation
Cyanide: Alkaline chlorination, ozonation
Manganese: Neutralization of acid salts, precipitation, sedimentation
Phenol: Biological oxidation, breakpoint chlorination, activated carbon
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
sulfuric acid solution can be used and pH controlled to within +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 a.2
and the reduced chromium is settled out. With proper operation, the
hexavalent chromium should be completely reduced. The 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 N2 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.
Manganese and iron, to the extent they 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 by 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 fcy chlorine and
chlorine dioxide (Ref. 34). Chlorine dioxide must, of course, be
generated on-site. Phenol can also be removed by absorption on
68
-------
activated carbon. Biological oxidation may be unfeasible for this
industry with its generally low BOD levels, although it may be usable if
nutrients are added. Activated carbon absorption is also possible as a
treatment technique, as is breakpoint chlorination.
The treatment processes discussed here are conventional. There 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.
The choice of air pollution control technology is of 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 which 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 31-89, 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 ether cases where the net concentration is zero, it
is because the average concentration is the same as or less than that of
the intake water.
The test methods used for the constituents of the waters are as follows:
pH - Standard Method No. 221, Aluminum, Chromium, Iron (Total), Lead,
Manganese, and Zinc - Standard Method No. 129 (Atomic Absorption),
Cyanide - Standard Method Nos. 207A, 207C, Phenol - Standard Method Nos.
222A, 222B and 222D, Phosphate - Standard Method No. 223E, and Suspended
Solids T Standard Method No. 148C. With the exception of the test
procedure for suspended solids, the tests used are identical with those
specified for use for monitoring under the NPDES system (38 C.F.R., Part
136). The test for suspended solids gives results within the
experimental error of the NPDES test method. 'Standard Method' refers
to methods contained in "Standard Methods for Examination of Water and
Wastewater," Thirteenth Edition, 1971, American Public Health
Association.
69
-------
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 1968, and a 20 mw furnace is
currently under construction. The large furnace produces 50-85 percent
FeSi. The other furnaces produce 50 percent FeSi, proprietary silicon
base alloys, and a rare earth silicide. Chromium alloys have been
produced in the past. No wet air pollution controls are used; baghouses
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 built in 1952 and serves the
three 10 mw furnaces. It is being automated and modified 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 used in each system. Blowdown
from the Nc. 1 tower is manual and from No. 2 tower is automatically
controlled by total solids levels. A softener is used in the No. 2
tower system with bulk salt used as a regenerant. Recirculated 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 neec j. Recirculation flow
in the No. 2 tower system is 284 I/sec (4500 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 only of 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 off originating in
the hills behind the plant. This has reduced the wet 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 31 through 35. The
temperature drop across cooling tower No. 1 was determined to be 6.70C
(12°F). The operating power on the furnaces served by this tower during
the sampling period was 21.9 mw.
70
-------
Figure 7.
PLANT A WATER AND WASTEWATER SYSTEMS
DRAINAGE
FURNACE
CONDENSATE
BACKWASH
STORM
SEWER
TO
RIVER
WATER
ORE FIELD i,
DRAINAGE
YARD
DRAINAGE
LABORATORY
DRAINAGE
YARD
DRAINAGE
SEPTIC
SYSTEM
OVERFLOW
LAGOON
-------
Table 31 ANALYTICAL DATA -SPA- 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
= 6-7 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 32 ANALYTICAL DATA -SPE - 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 = 6«7 I/sec. ( 106
Average Temperature =13.3°C (56 °F)
72
-------
Table 33 ANALYTICAL DATA -SPC- PLANT 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 noted)
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
Average
.27
.01
.39
. ( gpm)
Table 34 ANALYTICAL DATA -SPD - PLANT A
COOLING TOWER #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
Maximum
500
-
0.
0.
0.
0.
—
0.
5.
-
8.
53
8
38
055
57
26
3
(except as
noted)
Average Net Average
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
73
-------
Table 35 ANALYTICAL DATA -SPE" PLANT
WELL WATER
Constituent
Concentrations, mg/1 (except as noted)
Minimum Maximum Average Net Average
Suspended Solids 8 16 13
Total Chromium -
Hexavalent Chromium -
Total Cyanide - -
Free Cyanide - -
Manganese 0.32 0.32 0.32
Oil 0.6 1.0 0.8
Iron - 0.06 0.03
Zinc 0.022 0.07 0.044
Aluminum - - -
Phenol 0.30 0.41 0.34
Phosphate - 0.14 0.08
Lead -
pH (units) 6.9 7.7 7.3
Average Flow = I/sec. ( gpm)
Table 36 ANALYTICAL DATA -SPA- PLANT B
INTAKE WATER
Constituents
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 =
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)
74
-------
PLANT E
This plant has been operating since 1939 and has four covered submerged-
arc furnaces producing 50 percent ferrosilicon, 75 percent ferrosilicon
and silicon-manganese-zirconium (SMZ). These furnaces have a total
rating of 71.0 mw and operated during the plant survey period at 51.3
mw. The water and waste water system for the plant is shown in Figure
8.
The four covered furnaces use cooling water on a once-through basis and
the sewage by the 350 employees is treated at an on-site plant. The
total effluent is 30,282 cu. in/day (8 mgd) . Water is drawn from a
surface source.
The fumes from the four furnaces are scrubbed using seven Buffalo Forge
(disintegrator) scrubbers, each using 15.78 I/sec (250 gpm) of water.
During the plant survey, one furnace had only one scrubber, each of the
other furnaces had 2 scrubbers; a second scrubber was being installed on
the first furnace. The scrubber water is combined at a lift station
where lime and chlorine are added to oxidize the cyanides produced in
the covered furnaces. The scrubber water then flows through 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 flocculant are
added for improved sedimentation. The clariflocculator underflow is
returned to the first lagoon and 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 efflueiit was determined by measurements over a
rectangular weir and the sewage plant effluent was measured by bucket
and stopwatch. The yard drainage flow was estimated. The furnace
cooling water flow was determined by difference and checked by a
calculated chloride balance. The discharge permit data for this 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 percent of the cooling water
is recirculated and the flow obtained during the plant survey was judged
to be correct.
75
-------
The total operating loads on the furnaces during the sampling was 5H.3
mw. summarized analytical data are shown for the sampling points as
designated in Figure 8 in Tables 36 through 42.
76
-------
Figure 8.
PLANT B WATER AND WASTEWATER
SYSTEMS
FURNACE
COOLING
WATER
YARD DRAINAGE
SEWAGE TREATMENT
PLANT
FFLUENT
4-COVERED ELECTRIC
SUBMERGED ARC
FURNACES
FOR
COOLING
INFLUENT
WATER
7-WET
SCRUBBERS
CHLORINE
LIME
DEMERGE NCY_
OVERFLOW
DISPOSAL LAGOON
2.5 ACRES
| ^ W 1
LIFT
STATION
i
DISPOSAL LAGOON
13.5 ACRES
i
1
1
1
x UNDERFLOW
• v
i
LIME FLOCCULANT
i 1
DISPOSAL LAGOON
17 ACRES
fr\ fc r i ADiCiorrill AT
OVERFLOW
OR
SETTLING LAGOON
0.25 ACRES
CHLORINE ^OVERFLOW
pH CONTROL ©
SETTLING LAGOON
I.I ACRES
SETTLING LAGOON
I.I ACRES
-------
Table 37 ANALYTICAL DATA -SPB • PLANT B
WET SCRUBBERS
Concentrations ,
Constituent
Suspended Solids
Total Chromium
Hexavalent Chromium
Total Cyanide
Free Cyanide
Manganese
Oil
Iron
Zinc
Aluminum
Phenol
Phosphate
Lead
pH (units)
Average Flow
mg/1 (except as noted)
Minimum Maximum
968
-
—
1.
0.
15.
2.
6.
1.
0.
5.
0.
1.
6.
= 126
2
18
20
9
4
1
46
69
62
54
43
2
I/sec
,242
-
—
3.
1.
38.
7.
8.
3.
1.
9.
2.
1.
6.
. (2,
28
57
6
6
9
10
29
05
25
96
4
000
Average
1,555
—
_
2.
1.
24.
4.
7.
2.
0.
7.
1.
1.
6.
gpm)
49
04
0
5
8
10
99
27
11
71
3
Met Average
1,535
0
0
2
1
24
3
6
2
0
7
0
1
.48
.03
.0
.7
.5
.08
.99
.27
.88
.71
Table 38 ANALYTICAL DATA -SPC - PLANT B
THICKENER INLET
Constituents
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 =
70
0.15
0.15
2.58
0.6
0.79
0.94
0.43
0.45
96
0.36
0.36
2.97
2.2
1.
1
14
08
0.29
0.44
0.54
83
0.22
0.22
2.84
1.2
0.95
1.01
0.19
0.43
0.51
6.3 6.9 6.6
126 I/sec. (2,000
63
0
0.21
0.21
2.82
0.4
0
0.99
0.19
0.43
0.28
0
78
-------
Table 39 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
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 I/sec
86
0.01
_
0.34
0.34
0.93
3.0
0.50
0.39
—
0.51
0.54
0.05
9.6
. (2,000
Average
56
—
_
0.21
0.21
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
0.88
1.4
0
0.36
0
0.50
0.18
0.03
Table 40 ANALYTICAL DATA -SPL - PLANT B
COOLING WATER
Concentrations, mg/1 (except as
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.
1.
0.
0.
—
0.
-
6.
006
025
6
20
044
47
22
7
Maximum
22
—
-
0.
-
0.
0.
1.
0.
0.
-
0.
-
8.
061
025
8
34
044
47
22
5
Average
11
—
-
0.
-
0.
0.
1.
0.
0.
—
0.
—
7.
025
025
7
27
044
47
22
9
Net
0
0
0
0.
0
0.
0
0
0.
0.
0
0
0
noted)
Average
020
007
024
47
Average Flow = 217 I/sec. (3,440 gpm)
79
-------
Table 41 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)
Concentrations, mg/1 (except as noted)
Minimum Maximum Average Net Average
20
0.01
52
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
Average Flow = 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 42 ANALYTICAL DATA -SP G- 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 (69.9F)
80
-------
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 tower and a low energy
(Dingier) scrubber. Water is recycled and reused in both the scrubber
system and the furnace cooling water system; the latter 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 of the scrubber
water flows. The thickener overflow is recycled to the scrubbers and
the underflow is treated in a series of 2 lagoons. The 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 tower is 14°C (25.2°F).
Summarized analytical data are shown for the designated sampling points
in Tables <*3 through 49.
81
-------
Figure 9.
PLANT C WATER AND WASTEWATER SYSTEMS
00
NJ
COOLING
TOWER
OTO
BLOW/gsDOWN
EMERGENCY
POLYELECTROLYTE
REFUSE
WATER
TANK
t
i
fc
SCRUBBE R
KMn04
-<£H
4
1
1 —
ACTIVATED
CARBON
FILTERS
THICKENER
DISCHARGE
SANITARY
TREATMENT
PLANT
CHLORINE
LAGOON
-------
Table 43 ANALYTICAL DATA -SPA- PLANT c
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 gpm)
Table 44 ANALYTICAL DATA -SPB - PLANT c
COOLING TOWER SLOWDOWN
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)
83
-------
Table 49 ANALYTICAL DATA -SPG- PLANT c
THICKENER OVERFLOW
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
100
5.01
0.73
51
2.8
0.27
1.00
4.1
0.47
1.02
7.2
252
6.48
1.12
82
4.0
0.43
2.80
9.4
0.86
4.0
0.80
7.7
181
5.60
0.90
71
3.4
0.38
1.73
6.2
0.64
2.05
0.49
7.5
180
0
0
5.60
0.90
71
3.2
0
1.70
6.2
0.64
2.05
0.49
Average Flow = 67.7 I/sec. (1,075 gpm)
Table 50 ANALYTICAL DATA -SPA - PLANT D
WELL WATER
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
16
0.20
2.24
0.026
0.20
2.30
0.026
13
0.20
2.27
0.026
0.02 0.04 0.03
6.1 7.9 6.7
Average Flow =16.3 I/sec. ( 259 gpm)
86
-------
PLANT C
This plant has open submerged-arc furnaces which produce ferrochromium,
ferrosilicon, blocking chrome, and ferromanganese. Three of the
furnaces are rated at 5.5 mw and the fourth at 16.5 mw.
These furnaces are equipped with a new type of dust-removal system
utilizing waste heat from the furnace to provide the energy for gas
scrubbing without the use of exhaust fans. This system has recently
been installed on four ferroalloy furnaces. The reaction gas passes
through a heat exchanger, a nozzle, and a separator. The heat from the
reaction gases is transferred to the water in the heat exchanger,
increasing the temperature of the water to about 177-204°C (350-400«F)
and the water pressure to about 21 kg/sq cm (300 psi). As the heated
water is expanded through the nozzle of the scrubber, partial flashing
occurs, and the remaining liquid is atomized. Thus, a two-phase mixture
of steam and small droplets leaves the nozzle at high velocity. The
reaction gas from the furnace is entrained by this high velocity, two-
phase mixture, and in the subsequent mixing, the reaction gas is
scrubbed and cleaned. At the same time, the action of the gases leaving
the nozzle aspirates the reaction gases from the furnace and propels
them through the system. The mixture of steam, gas, and water droplets
entrained with the collected particulates from the gas passes through a
separator after discharge from the mixing section. The water and dust
are removed from the gas-steam mixture; the gas leaves the separator
through the stack, and the water and dust are discharged from the
separator to a waste water treatment system. Chemicals 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 the heat exchanger.
Makeup water is added to replace any losses.
The water flow diagram is shown in Figure 11. The clarifiers consist of
3 inclined, tube-type clarifier-flocculators in parallel. The filters
are 3 deep-bed sand filters in parallel; backwash on the 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 (58.5 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 percent ferrosilicon. The average daily power
consumption on the furnaces totaled 695.5 mwhr.
87
-------
Summarized analytical data for various sampling points as designated in
Figure 11 are shown in Tables 50 through 55.
88
-------
Figure IO.
STEAM/HOT WATER SCRUBBING SYSTEM
CO
OFFTAKE
DUCT
EMERGENCY
STACK
HEAT
EXCHANGER
CLEAN GAS
DISCHARGE
PRIMARY
PUMPS
NOZZLE
MIXING DUCT
SEPARATOR
CLARIFIER
PUMP HOUSE
FURNACE
ENCLOSURE
-------
Figure I /.
PLANT D WATER AND WASTEWATER SYSTEMS
BLOW DOWN
PLANT
DISCHARGE
BLOW
PH
ADJUSTMENT
CELL
BRINE
T
COOLING
TOWER
$ '
WELL
t.
9 PUMro
-—
MAKE UP TO
SCRUBBERS *
^-
FURNACES !—• 1
")
SCRUBBERS
_/
1
\_/
' t
* — '>
' 1 1
BLOV/IDOWN
SOFTENER
-------
Table 51 ANALYTICAL DATA -SPB- 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.
-
0.
0.
3.
0.
0.
_
1.
—
6.
= 0.38
007
09
2
08
059
7
95
2
I/sec
28
_
_
0.
-
0.
0.
3.
0.
0.
_
2.
-
7.
. (
007
14
2
15
077
7
77
8
6
Average
19
—
_
0.007
-
0.11
0.2
3.10
0.069
0.7
_
2.54
—
6.8
gpm)
Net
6
0
0
0
-
0
0
0
0
0
2
0
Average
.007
.2
.83
.043
.7
_
.51
Table 52
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
1.69
0.70
25.6
25.1
58.6
0.24
3.92
3.03
Average Flow =21.6 I/sec. (343.5 gpm)
91
-------
Table 53 ANALYTICAL DATA -SPL- 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
0.60
1.6
0.77
0.325
0.6
0.30
0.10
38
0.46
0.014 0.005
0.25
1.0
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
Table 54 ANALYTICAL DATA -SPD - PLANT D
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
0.42
0.3
1.53
0.288
0.7
-
0.01
—
9.1
19.2 I/sec
134
0.43
0.029
1.23
1.6
6.15
2.51
1.8
0.23
0.18
0.42
10.3
. ( 305
112
0.31
0.024
3,
1,
0.78
1.1
15
24
1.3
0.12
0.07
0.14
9.7
99
0.31
0.024
0.58
1.1
0.88
1.21
1.3
0.12
0.04
0.14
gpm)
92
-------
Table 55 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
8.4
532
1.35
0.215
0.030
3.25
0.61
7.83
3.79
0.05
0.10
0.63
9.6
186
0.87
0.177
0.025
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)
93
-------
PLANT E
This plant has been operating since 1951 and has principally two areas
where waste waters other than cooling waters are generated and
discharged. These two areas contain electric arc furnaces and
electrolytic cells, respectively.
There are seven covered and two open submerged-arc furnaces where 50
percent ferrosilicon, silicomanganese, standard and medium carbon
ferrcmanganese, and high carbon ferrochromium are produced. This area
also contains metals refining and slag shotting operations. These
furnaces have a total rating of 126 mw and operated during the survey
period at 82 mw.
The nine furnaces use cooling water on a once-through basis. The
sanitary sewage is treated at an on-site plant and discharges with the
cooling water. The total plant effluent is 1.16 X 106 cu. m/day (305.5
mgd), the majority of which is cooling water from the plant's power
generating station.
The water and waste water systems for the plant are shown in Figure 12.
Also shown in this figure are the sampling points used during the
survey.
The fumes from the furnaces are scrubbed with either venturi or
disintegrator type scrubbers. There are five venturi and 12
disintegrator type scrubbers available for the nine furnaces. The
scrubbers use between 22-32 I/sec (350-500 gpm) of the water when
operating. The metals refining operation also utilizes a venturi
scrubber. The scrubber water flows via a common line to the first of
two lagoons operated in series. The lagoons have a combined surface
area of 78 acres. The wash water from the electrolytic operations mixes
with the scrubber waste water before entering the lagoons.
The acid waste water from the electrolytic operations flows to the
second of these lagoons where a hydrated lime slurry is also added as a
neutralizing agent. This second lagoon also receives the effluent from
a flyash removal system at the power plant. The effluent 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 56 through 72. The 1971 average temperature
increase in cooling water temperatures over inlet was 3.9°C (7°F).
-------
Figure \i.
PLANT E WATER AND WASTEWATER SYSTEMS
CHLORINE
CHLORINE INFLUENT WATER
IJFROM RIVER
FOR MISCELLANEOUS
OPERATIONS
SLUDGE LAGOON N0.3
69.6 ACRES
OUTFALL
TO RIVER
OUTFALL
TO RIVER
OUTFALL
TO RIVER
OUTFALL
TO RIVER
OUTFALL
TO RIVER
-------
Table 56 ANALYTICAL DATA -SPA- PLANT
FURNACE A SCRUBBER 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
210
0.01
54
1.2
5.26
18
4.45
1.79
7.0
342
0.01
54
1.2
5.26
18
4.45
1.79
7.1
261
0.01
54
1.2
5.26
18
4.45
1.79
7.0
228
0
0
0
0
54
1.2
4.68
18
3.78
0
0
1.79
Average Flow = 28.4 I/sec. ( 450 gpm)
Table 57 ANALYTICAL DATA -SPB - PLANT
FURNACE B SCRUBBER 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
318
0.09
0.87
256
1.6
18.0
48
13.0
0.22
5.6
6.4
426
0.09
0.87
256
1.6
18.0
48
13.0
0.22
5.6
6.9
373
0.09
0.87
256
1.6
18.0
48
13.0
0.22
5.6
6.7
340
0.09
0.87
256
1.6
17.4
48
12.3
0.22
0
5.6
Average Flow =25.2 I/sec. ( 400 gpm)
96
-------
Table 58 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 59 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)
(about 2U min/nr)
97
-------
Table 60 ANALYTICAL DATA -SPL- 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 61 ANALYTICAL DATA -SP F - 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)
98
-------
Table 62 ANALYTICAL DATA -SP G - PLANT E
FURNACE E SCRUBBER 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
3,244 4,
0.50
_
-
-
1,576 1,
—
6.94
51
178
0.09
-
11.7
8.6
=44.1 I/sec.
140
0.50
_
-
-
576
-
6.94
51
178
0.09
-
11.7
8.7
( 700
Average
3,753
0.50
_
—
-
1,576
-
6.94
51
178
0.09
-
11.7
8,6
gpm)
Net Average
3,720
0.34
—
0
0
1,576
-
6.36
51
177
0.09
0
11.7
Table 63 ANALYTICAL DATA -SPH - PLANT E
FURNACE E SCRUBBER SETTLING BASIN 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
3,348
0.17
_
-
-
1,322
1.0
7,16
89
178
-
-
9,1
8.5
Maximum
11,364
0.17
_.
-
~
1,322
1.0
7.16
89
178
-
-
9.1
8.6
Average
6,080
0.17
_
-
-
1,322
1.0
7.16
89
178
-
-
9.1
8.6
Net Average
6,047
0.01
_
0
0
1,322
1.0
6.58
89
177
0
0
9.1
Average Flow = 44.1 I/sec. ( 700
99
-------
Table 64 ANALYTICAL DATA -SPI - PLANT
SLAG CONCENTRATOR WASTEWATER
Concentrations, mg/1 (except as noted)
Constituent MinimumMaximum 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 0
Phosphate o
Lead 0
pH (units) 6.1 6.2 6.2
Average Flow = 107.ll/sec. (1,700
Table 65 ANALYTICAL DATA -SPJ - 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 gpm)
100
-------
Table 66 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
T1
-
25.4
0.4
1.28
5.55
2.04
_
-
0.04
6.8
gpmj
150
0.61
0.198
0
0
24.9
0.4
0.70
5.53
1.37
0
0
0.04
Table 67 ANALYTICAL DATA -SP L - PLANT E
LAGOON #3 EFFLUENT
Concentrations, mg/1 (except as
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
Average
15
0.
_
0.
-
91
0.
0.
0.
0.
—
0.
—
7.
08
005
2
35
34
15
9
2
Net
0
0
_
0.
0
91
0.
0
0
0
0
0.
0
noted)
Average
005
2
9
Average Flow = 632.81/sec. (10,045 gpm)
101
-------
Table 68 ANALYTICAL DATA -SP M- PLANT
INTAKE RIVER 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
24
0.16
0.49
0.54
0.022
0.67
38
0.16
0.49
0.2
0.62
0.022
0.67
33
0.16
0.49
0.58
0.022
0.67
7.2 7.2 7.2
Average Flow = 13,366 I/sec. ( 212,150
Table 69 ANALYTICAL DATA -SPN - PLANT E
COOLING WATER 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
90
6.6
0.053
3.42
0.045
4.28
1.98
3.8
176
6.6
0.014
4.61
0.4
32.
0.045
4.28
1.98
7.2
125
6.6
0.005
1.58
0.3
15.0
0.045
4.28
1.98
5.4
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)
102
-------
Table 70 ANALYTICAL DATA -SPO - PLANT E
COMBINED SLAG SHOTTING & COOLING WATER DISCHARGE
Constituent
Suspended Solids
Total Chromium
aexavalent 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 71 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)
103
-------
Table 72 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 73 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)
Concentrations, mg/1 (except as noted)
MinimumMaximum 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
Average Flow = 25.2 I/sec. ( 400 gpm)
104
-------
PLANT F
This plant utilizes seven electric arc furnaces to produce a product
line including 50 percent ferrosilicon, low carbon ferrochromesilicon,
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. Slowdown 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 percent 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 percent of the recirculating flow. Two additional furnaces with a
capacity of 65 mw are served by a 316 I/sec (5000 gpm) recirculating
flow and a bleed-off of 13 I/sec (200 gpm) or 4 percent of the flow.
Water treatment in the cooling system consists of a chromate based
proprietary compound and algaecides.
Except for the overflew from septic tanks and isolated roof 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 73 through 75. 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 is
blowdown to a closed lagoon i.e., a lagoon with no outlet. This process
was not operating at the time of our visit. The plant reports the
blowdown rate to be 1.58 I/sec (25 gpm) from this system, while the
total circulation rate is 94.65 I/sec (1500 gpm).
105
-------
PLANT G
This plant has two 35 mw open furnaces which produce ferrochromium and a
slag concentration operation. At times ferrochromesilicon 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 the performance of
the precipitators; ammonia is added to the spray water.
The water supply is purchased city water and originates from wells. The
cooling water used on the furnaces is recirculated through a cooling
tower at the rate of 316 I/sec (5000 gpm). The spray towers remove a
portion of the particulates from the furnace gases prior to the
precipitators; the resultant slurry passes through settling basins near
the furnaces and then a lagoon which has been excavated from a slag
pile.
The slag concentrator is a sink-float process in which slag fines are
separated from larger, usable slag particles and in turn from
recoverable metal. The products are thus slag for sale and 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 kkgs (270 short tons) of alloy
per day. Reference 32 indicates a factor of 4.3 mwhr per ton, i.e., a
furnace load of 1,134 mwhr per day. Analytical data are summarized in
Tables 76 through 81, for sampling locations designated in Figure 14.
108
-------
Figure 14.
PLANT G WATER AND WASTEWATER SYSTEMS
CITY
WATER
FURNACE
COOLING
TOWER
i
r
fc
FURNACE
SPRAY
TOWER
SETTLING
BASIN
SPRAY
TOWER
SETTLING
BASIN
LAGOON
LAGOON
LAGOON
SLAG
CONCENTRATION
-------
Table 76 ANALYTICAL DATA -SP A PLANT
INTAKE CITY WATER
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
0.030
0.2
0.13
0.159
6.9
7.9
7.3
Average Flow =20.5 I/sec. ( 325 gpm)
Table 77 ANALYTICAL DATA -SP B- PLANT
COOLING TOWER BLOWDOWN
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
7.3 8.4
1.6 I/sec. ( 25
25
3.31
1.49
0.094
0.3
0.32
0.65
0.98
0.12
8.0
25
3.31
1.49
0
0
0.064
0.1
0.19
0.491
0.98
0
0.12
0
110
-------
Table 78 ANALYTICAL DATA -SP C 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 Maximum Average Net Average
4,134
6,104
4,980
4,873
2.66
1.68
0.2
1.77
0.75
4.34
0.01
7.3
8.36
0.49
14.0
0.6
,50
,28
3,
5,
23.0
0.02
8.6
4.76
0.32
8.15
0.3
2.58
2.45
11.28
0.02
4.76
0.32
0
0
8.12
0.1
2.45
2.29
11.28
0
0.02
0
8.1
Average Flow = 1.1 I/sec. ( 17.5gpm)
Table 79 ANALYTICAL DATA -SP D PLANT G
SETTLING BASIN EFFLUENT
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
784
5.29
3.33
0.4
2.95
4.75
21.9
0.03
8.3
784
5.29
0
0
0
3.30
0.2
2.82
4.59
21.9
0
0.03
0
Average Flow = 3.8 I/sec. ( 60 gpm)
111
-------
Table 80 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
—
—
-
O.a7
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
_
_
—
1.20
1.1
0.60
0.84
2.57
_
0.04
—
8.1
gpm)
Net Average
101
2.52
0
0
0
1.17
0.9
0.47
0.68
2.57
0
0.04
0
Table 81 ANALYTICAL DATA -SP F - 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)
112
-------
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 dichrornate. 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 fcatchwise in a series of rubber 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. 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
would almost triple their capacity. Currently, gravity flow is used,
but provisions have been made for the later addition of pumps if needed.
113
-------
Sludge production is expected to approach 454 kg/day (1,000 lb/ day).
Approximately six months of sludge storage is provided before removal
would be required. This storage capacity will allow for 180 days of
continuous operation at the maximum flow and chromium concentrations.
Analytical data from the plant survey are summarized in Tables 82
through 89 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 IT
(200 ft. X 220 ft.) .
114
-------
Figure ISL
DIAGRAM OF*WET BAGHOUSE* SYSTEM
FIRING CUBICLE
WITH
FIRING POT
U1
DUCTS WITH
WATER SPRAYS
BAGS CLEANED BY
INTERNAL WATER SPRAY
MAIN EXHAUST FAN
SLURRY TO
DRAIN
(CLEANED GAS TO ATMOSPHERE)
-------
Figure 16.
PLANT H WATER AND WASTEWATER SYSTEMS
GASES
t
EXOTHERMIC
SMELTING
OPERATION
ft-
BAG HOUSE
CITY
WATER
TO STREAM
SE
*
}
TREATMENT
LAGOON
(LINED)
^ASONAL BY- PASS
THERMAL
POND
(UNLINED)
fr\
i
\ii/
t
fo
SETTLING
LAGOON
(LINED)
k
POLISHING
LAGOON
(LINED)
T
4 ^ ru\
1
COOLING
WATER
-------
Table 82 ANALYTICAL DATA -SPA- 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 83 ANALYTICAL DATA -SP B- 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
220
121
44
136
112
37
0.040
1.2
0.04
0.002
O.U51
2.6
0.04
0.003
0.048
1.8
0.04
0.002
12.3
12.4
12.3
Average Flow = 100,303 I/da (26,500 gal/da)
136
112
37
0
0
0.022
1.8
0
0
0
0
0
0
117
-------
Table 84 ANALYTICAL DATA -SPC- PLANT
TREATED BAGHOUSE WASTEWATER
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
674
114
Maximum
748
114
0.047 0.363
_
-
0.41
0.8
2.64
0.90
127
—
0.41
—
4.7
= 100,303
_
—
0.73
2.0
3.73
1.53
130
—
0.50
—
6.2
I/da (26,500
Average
713
114
0.162
_
_
0.54
1.3
3.27
1.27
129
_
0.46
—
5.4
gal/da)
Net Average
713
114
0.162
0
0
0.51
1.3
3.01
1.25
129
0
0.46
0
Table 85 ANALYTICAL DATA -SP D - PLANT H
SETTLING LAGOON DISCHARGE
Concentrations, mg/1 (except as noted)
Constituents
Suspended Solids
Total chromium
Hexavalent chromium
Total Cyanide
Free Cyanide
Manganese
Oil"
Iron
Zinc
Aluminum
Phenol
Pnosphate
Lead
pH (units)
Average Flow
Minimum Maximum
58
17.9
0.189
-
-
0.70
3.4
0.24
0.77
31
-
0.05
—
4.9
= i/sec
70
18.3
0.218
-
-
0.70
3.4
0.42
0.77
31
-
0.05
—
4.9
. (
Average
66
18.1
0.208
-
-
0.70
3.4
0.32
0.77
31
-
0.05
-
4.9
gpm)
Net Average
66
18.1
0.208
0
0
0.67
3.4
0.06
0.75
31
0
0.05
0
118
-------
Table 86 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
10
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
38
7.40
0.245
_
—
0.92
4.0
0.17
0.44
15.3
_
0.05
—
5.2
gpm)
Net Average
38
7.40
0.245
0
0
0.89
4.0
0
0.42
15.3
0
0.05
0
Table 87 ANALYTICAL DATA -SPF - PLANT
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
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
119
-------
Table 88 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)
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
Average Flow = 3.01 i/sec. ( 48 gpm)
Taole 89 ANALYTICAL DATA -SP H - PLANT H
COOLING WATER
Constituents
Suspended Solids
Total Chromium
Hexavalent Cnromium
Total Cyanide
Free Cyanide
Manganese
Oil
iron
Zinc
Aluminum
Phenol
Phosphate
Lead
pti (units)
Concentrations, mg/1 (except as noted.)
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
Average Flow =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
120
-------
In Figure 17, a waste treatment scheme is shown in which all of the
waste constituents for which guidelines have been developed 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 manganese is precipitated as the hydroxide. In
the second step, additional chlorine is added and the pH is lowered to
7.0 by a suitable acid. With a reaction time of 60 minutes, the cyanate
is oxidized to CO_2 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 to trivalent. The fourth step
consists of raising the pH to 8.2, adding a polyelectrolyte, and
allowing sedimentation. At this point, the trivalent 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.
Obviously, not all plants will require the entire treatment system. For
example, plants (such as B or C) producing only manganese or only
silicon products in covered furnaces, will require only the first,
second and fourth (excluding raising the pH to 8.2) steps of the
treatment scheme for removal/destruction of cyanide, phenols, manganese
and suspended solids. A plant which specializes in chromium products
using open furnaces, would require only the third and fourth steps for
reduction of hexavalent chromium and removal of the trivalent and
suspended solids. For those plants which produce a variety of products,
an alternative solution may be the segregation of wastes and
installation of the various treatment modules for chromium reduction,
cyanide destruction, etc,, to be utilized in series or parallel as
required to achieve the proper results. This might result in
considerable economies over treatment of all wastes for all parameters.
Some plants which do not have any particular problem with metals or
cyanides may be able to use a system similar to that in practice at
Plant E, i.e., the addition of flyash from a nearby power station to
scrubber waste water, followed by settling. The average suspended
solids concentration reached by this system was 15 mg/1. It may be
useful to some plants to operate such a system, using existing lagoons,
to meet the 1977 standards.
121
-------
Figure 17. Diagram of Waste Water Treatment System
;£Gy
-------
Another alternative solution for 1977 might be the conversion of once-
through systems to recirculation, with only the blowdown treated for
removal of metals (obviously, recirculated water would need to be
treated for removal of! suspended solids) . Since less chemicals would be
required for treatment, in addition to smaller tanks, etc., this might
result in some savings over the costs estimated in Section VIII.
Some plants may be able to meet the 1977 guidelines simply by modifying
their present treatment system somewhat, while some other plants (such
as G) seem to meet all the 1977 pollutant load requirements for scrubber
waste water. For example, both plants C and D appear to meet all but
one of the 30 day average pollutant load requirements for 1977
(manganese and suspended solids, respectively). Plant C should be able
to meet fully the 1977 pollutant load standards by some additional
treatment for manganese removal prior to clarification. Plant D may be
able to rectify the suspended solids load by using more of their
clarification capacity (one of their three clarifiers was not operating
at the time of our visit), or by making the flow into the clarifiers
more quiescent (which may have caused improper distribution of the inlet
water), or by backwashing the sand filter more frequently.
Plant B apparently meets all 1977 pollutant load standards but that for
suspended solids (in spite of using water on a once-through basis). It
is possible that the suspended solids level after the final two settling
lagoons (which was not checked) may presently be low enough to meet the
standards, but possibly some additional clarification might be
necessary. Plant E probably meets the 1977 standard for suspended
solids (since the concentration at the outfall was 15 mg/1).
The treatment system as shown in Figure 17 is not utilized in toto in
any one plant in the industry. However, the modules which comprise the
system are in use in this, or similar, industries.
Plant P, studied as part of the Alloy and Stainless Steel Industry (Ref.
33), utilizes a treatment system for hexavalent chromium reduction,
neutralization and clarification almost identical to that shown in steps
3 and 4 of Figure 17. This system had an average influent
concentration of about 18 mg/1 total chromium and 16 mg/1 hexavalent
chromium. After treatment, the average concentrations were 0.10 and
less than 0.01 mg/1, respectively. This system was operating on a
continuous basis. Plant S of the Iron and Steel Industry study (Ref.
35), achieved an average suspended solids concentration of 22 mg/1 after
clarification of scrubber water from a B.O.F. Plant B achieved
concentrations of 0.22 mg/1 cyanide after alkaline chlorination, while
the phenol level was reduced to 0,50 mg/1. Plant D demonstrates the use
of alkaline precipitation of metals and the use of sand filters,
although not in a completely optimum manner. The treatment scheme shown
may be thought to be based upon the components of all these systems,
although as discussed above, any particular plant may not find it
necessary to utilize the entire system.
123
-------
Other treatment methods in use in the industry appear to be relatively
ineffective for some constituents. For examples, the relatively high
concentrations of suspended solids in the treated water from the
clarifier and the sand filter at Plant D has already been discussed,
along with suggestions as to the cause for such concentrations.
Although flyash treatment appears to work well for removal of suspended
solids, as utilized at Plant E, the same treatment has little or no
effect on the content of metals found in the effluent. Although the
potassium permanganate used at Plant C might be expected to oxidize the
cyanide as well as some of the manganese, such was not the case, since
the cyanide and manganese concentrations in the overflow were almost as
high as in the raw waste. It is possible that higher dosages may more
effectively oxidize these wastes, but the cost of such treatment would
almost certainly be higher than chlorination. 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 97 percent of the scrubber water was recirculated,
the only blowdown being the clarifier underflow.
The control and treatment technologies which have been identified herein
are identified as applicable to the various industry categories in Table
90.
Table 90. CONTROL AND TREATMENT TECHNOLOGIES BY CATEGORY
Treatment
Category Technology Description
I 1 Chemical treatment, clarifier-flocculators,
recirculation at the scrubber
2 Chemical treatment, clarifier-flocculators,
sand filters and process water recirculation
II 1 Chemical treatment, clarifier-flocculators
2 Chemical treatment, clarifier-flocculators,
sand filters and process water recirculation
III 1 Clarifier-flocculators, chemical
treatment (if necessary)
2 Clarifier-flocculators, chemical treatment
(if necessary), process water recirculation
-------
It should be noted that with the exception of the slag processing
operations, the raw waste loads and final effluent leads have been
calculated in terms of mwhr as the production basis. This was done for
the following reasons, after examining the other possible basis (kg
(tons) ) :
1. Uncontrolled emission factors (upon which the raw waste loads
depend), are more uniform over the various types of products when
expressed as kg (lb)/mwhrf rather than as kg/kkg (Ib/ton).
2. Power usage is already such a large factor in production costs (about
30 percent) that an increase in power consumption so that the
permissible effluent discharge would be higher is very unlikely.
3. Power usage is very well monitored at the furnace itiself, usually
with a continuous automatic recording device.
U. Furnaces are commonly referred to in the industry as '10 mw1 or '35
mw1, rather than '50 ton1 or "150 ton', 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 in writing a permit with
many different conditions. The reader may refer to Table 18 for
comparisons of power usage per ton for various products.
Aggregate raw waste loads, representing for some parameters such as
chromium and manganese the maximum load which might be expected in the
waste, are shown in Tables 91 through 93. The manganese concentrations,
for example, would probably only be encountered 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 of water (kg(lb)/hr) x concentration
•9 (10* x furnace power (mw))
load (kg/kkg (Ib/ton)) = mass flow rate of water (kg (Ib)/hr) x
concentration t (amount processed (kkg (tons)/hr) x 106)
Furnace power may be calculated by dividing the number of megawatt-hours
used in the furnace in a 24 hour period by 24 hours.
Tables 91-93, 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.
125
-------
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) ]. Concentrations
of suspended solids and manganese at that sample point adjusted
accordingly to compensate for increased flow. Chromium concentrations
taken from Plant G, sample point C.
Treatment Level 1 - Concentrations shown are those achievable by the
treatment system as shown in Figure 17, less the 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/mwhr).
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 blowdown rate of 783 1/mwhr (207
gal/mwhr) .
Category II - Covered Electric Furnaces and Other Smelting Operations
with Wet Air Pollution Control Devices.
Raw Waste Load - Concentrations and loads as at Plant E, sample point B,
except that chromium concentrations are taken from Plant G, sample point
C, and manganese concentrations taken from Plant C, sample point C.
Loads calculated from Plant B, sample point B, flow.
Treatment Level 1 - Concentrations same as for Category I, treatment
level 1, except that cyanide and phenol concentrations are based upon
those found at Plant E, sample point D. Loads in kg (Ib) /mwhr were
calculated using the flows found at Plant B, sample point D.
Treatment Level 2 - Concentrations same as for Category I, treatment
level 2, with cyanide concentration based on Plant E, sample point D.
Loads in kg (lb)/mwhr based on 1060 1 (280 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) than 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 - Based on use of clarifier-flocculators.
126
-------
Treatment Level 2 - Eased on recalculation of process water after
precipitation of fine suspended solids in clarifier-flocculators. Loads
based on a blowdown rate of 5419 1/kkg (1300 gal/ton).
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 the case of
phenol, the limitations are 1.5 times the 30 day average.
STARTUP AND SHUTDOWN PROBLEMS
There have been no problems of consequence identified in connection with
the startup or shutdown of production facilities insofar as waste water
control and treatment is concerned. 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.
Loss of power can effect most of the treatment systems such as chemicals
addition for flocculation, cyanide destruction, or chrcmium reduction-
precipitation. In such cases, however, the production process also will
stop and little effect on waste water treatment would result.
127
-------
Table 91 INDUSTRY CATEGORY I
FURNACLS WITH wnr AIR POLLUTION CONTROLS
tv)
CO
Haw V/aste Load
Level 1 Affluent
30 day Average 24 lir Maximum
Level 2 Llffluent
30 day Average 24 lir Mixi
Suspended Splids 24.0
Total Giror.iium
Hexavalent
ChrcarniUTi
Manganese
pH
Flew
kg/riwiir
24.0
.078
.005
10.07
Ib/i.n.'hr HKJ/I kg/nwhr U>/rvhr
52.8
.172
.012
22.17
1460 .160
4.76 .0032
.32 .0003
613 .032
.352
.007
.0007
.070
Value
1/mwhr
16,410
7.2
gal/irwhr
4335
1/mwhr
6382
liXJ/1
25.
.5
.05
5.
Value
6.0 - 9.
kg/irwlir Ib/r.wlir nirj/'i
.319 .703 50.
.006 .014 1.
.0006 .0014 .1
.064 .141 10.
k.-../r.Tv;hr
.012
.0004
.00004
.0039
.026
.0009
.0001-
.0086
mg/1
15.
.5
.05
5.
kn/r-,dir l\j/i.:.:\x r.-j/l
.024
.0008
.00008
.008
.052 30.
.0017 1.
.0002 .1
.017 10.
Value
0
gal/nwia-
1686
1/py/hr
783
6.0--
9.0
oal/rvhr
207
-------
Table 92 INDUSTRY CATEGORY II
COVERED ELECTRIC FURNACES AND OTHER SMELTING OPERATIONS
WITH WET AIR POLLUTION CONTROL DEVICES
NJ
Raw Waste Load
Suspended Solids
Total Chromium
Hexavalent
Chromium
Total Cyanide
Manganese
Phenol
Flow
kg/mwhr
13.02
0.040
0.003
0.021
3.74
0.061
gal/mwhr
2210
Ib/mwhr
28.67
0.088
0.006
0.046
8.24
0.134
lA.hr
8365
mg/1
1555.
4.76
0.32
2.49
447.
7.27
Level I Effluent
30 Day Average 24 hr Maximum
kg/mwhr
0.209
0.004
0.0004
0.002
0.042
0.004
Ib/mwhr
0.461
0.009
0.0009
0.005
0.092
0.009
gal/mwhr
2210
Value
PH
6.0-9
.0
mg/1 kg/tawhr Ib/mwhr
25. 0.419 0.922
0.5 0.008 0.018
0.05 0.0008 0.0018
0.25 0.004 0.009
5.0 0.084 0.184
0.5 0.006 0.013
1/mwhr
8365
Value
6.0-9.0
Level 2 Effluent
30 Day Average 24 hr Maximum
mg/1 kg/mwhr Ib/mwhr mg/1 kg/mwhr
50.
1.0
0.1
0.5
10.
0.7
0.016 0.035
0.0005 0.0012
0.00005 0.0001
0.0003 0.0006
0.005 0.012
0.0002 0.0005
gal/mwhr
280
15. 0.032
0.5 0.001
0.05 0.0001
0.25 0.0005
5. 0.011
0.2 0.0004
lA^nr
1060
Value
6.0-9.0
Ib/imvhr
0.071
0.002
0.0002
0.001
0.023
0.0009
roVl
30.
1.0
0.10
0.5
10.
0.4
-------
Table 93 INDUSTRY CATEGORY III
SLAG PROCESSING
U)
O
Level 1 E
Raw Waste Load 30 Day Average
Suspended Solids
Total Chrondum
Manganese
pll
Flow
kg/kkg
processed
46.0
0.109
2.87
1/kkg
53,100
Ib/ton
processed
91.9
0.217
5.74
Value
6.2
gal/ ton
12,750
kg/kkg
mg/1 processed
864. 1.330
2.04 0.026
54. 0.266
Ib/ton
processed
2.659
0.053
0.532
1/kkg
53,100
mg/1
25.
0.5
5.
Value
••^MIWMI
6.0 - 9
ffluent
24 hr Maxirun
kg/kkg
processed
2.659
0.053
0.532
Ib/ton
processed ir*r/l
5.319 50.
0.106 1.
1.064 10.
30
kg/kkg
processed
0.136
0.0027
0.027
Level 2
Day Average
Ib/ton
processed mri/1
0.271 25.
0.0054 0.5
0.054 5.
Effluent
24 hr Maxirwm
kg/kkg Ib/ton
processed processed irxr/1
0.271
0.0054
0.054
0.542 50.
0.011 1.
0.108 10.
Value
.0
gaVton
12,750
6.0 -
1/kkg
5419
9.0
Ib/ton
1300
-------
SECTION VIII
COST, ENERGY AND NONWATER QUALITY ASPECT
Capital and operating cost information was obtained from each plant
surveyed. The capital costs (per mw capacity) for water treatment
systems at the plants surveyed varied from $5,581 (for an extensive
lagooning system with a clarifier) to $21,760 (for a treatment and
recirculation system). Operating costs varied from a low of $0.010/mwhr
(for settling ponds) to a high of $0.652/mwhr (for a treatment and
recirculation system).
Capital costs are given in terms of installed capacity and operating
costs in terms of units of production and also in terms of waste water
flows. These costs were based upon cost of capital at an interest rate
of 8 percent, and a depreciation period of 15 years.
Capital costs have been adjusted to August, 1971 dollars using the
Chemical Engineering Plant Cost Index (1957-59=100), This index has
been indicated by a consultant to The Ferroalloys Association to be best
indicative of cost changes in the industry. Operating costs have been
adjusted when necessary on the basis of an average of 3.5 percent per
year.
Power costs were calculated on the basis of flow rates and pumping head,
and have been assumed at one cent per kwhr, which is the cost used in
the EPA-TFA Air Pollution Study (Ref. 32). This estimate has been
confirmed by The Ferroalloys Association as being equal to the average
cost in the industry.
The cost of land was not included as part of the total investment, since
it is thought that very few (if any) plants will need to purchase land
for wastewater treatment. Of the seven plants which were visited which
used seme type of wet air pollution control system, six were sampled and
are discussed in Section VII. Three of the plants which were visited
had multi-acre lagoon systems, which could either be utilized as part of
wastewater treatment system, or used for landfilling sludge. The ether
four plants had varying degrees of treatment systems presently in use.
Those two which appeared to have the least amount of land available, are
in such position as to already meet all (or most of) the standards. The
remaining two plants appeared to have sufficient land so as not to
require the purchase of additional land. The treatment system at Plant
D, for example, was housed in a building about 50' x 100' with two
lagoons totalling about another 50' x 100'. Being generous, this would
give a total land requirement of about a third of an acre. Therefore,
it is not anticipated that the cost of acquiring land for those few
plants which may require it would add more than $2,000 to the total
investment cost. Additionally, the cost would be for the entire plant,
not merely per mw of capacity, so that for a small, 20 mw plant, the
131
-------
added investment for land would probably be less than 1 percent of the
cost of the treatment system.
The following bases were used for cost calculations by Category and
Treatment Level:
Category I, Treatment Level 1.
Costs were developed for the treatment system as shewn in figure 17, on
the basis of a 63.1 I/sec (1000 gpm) 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 mechanical 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 particular
plant may not require all the treatment steps. The investment costs
will probably be less (per mw) for a plant larger than the model, and
greater for a plant smaller than the model.
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 percent of the
capital cost per annual unit of production. The operating costs at
Plant C are equal to 23.H percent per year of the capital cost. The
operating costs at Plant D are equal to 23.0 percent of the capital
cost. The operating costs at Plant B are equal to 30.9 percent per year
of the capital costs. Operating costs are thus estimated on the basis
of 30 percent 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 of recirculation
and sand filtration, with a proportionate increase in annual and
operating costs.
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 B, sample point B, (8365 1/mwhr
[2210 gal/mwhr]), is equivalent to the flew 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.
132
-------
Category III, Treatment Level 1.
Costs were calculated for two clarifier flocculators, with the necessary
piping, pumps and other appurtenances. Costs were based upon the use of
53,148 1/kkg (12,750 gal/ton) processed.
Category III, Treatment Level 2.
Costs are greater than for Level 1 by the addition of pumps and pipes
necessary for recycle.
The costs for each are summarized in Tables 94 and 95.
Figures 18 through 20 show the relative costs of treatment for reduction
of effluent loads of the critical pollutants from the raw wastes. These
curves provide graphical information of interest, but must be read in
the context of the previously described Treatment Levels to be of value.
133
-------
Table 94. TEEATHLNT LLVKL COSTS ON ULJIT OP PRODUCTION BASIS
(costs on basis of raw and rawhr unless noted thus*)
Annual
Inudstry Category
and Treatment Level
Category I:
Treatment Level
Treatment Level
Category II:
Treatment Level
Treatment Level
Category III:
Treatment Level
Treatment Level
1
2
1
2
1
2
($
17
21
22
27
2
2
Investment
per mw or tpd)
,143
,063
,222
,303
.526*
,604*
Costs ($ per mwhr or ton)
Operating Cost
Capital
0.103
0.127
0.134
0.165
0.344*
0.357*
Depreciation
0
0
0
0
0
0
.138
.169
.178
.219
.459*
.485*
0
0
0
0
0
0
less Power
.606
.745
.785
.965
.421*
.421*
Pov.'er
0
0
0
0
0
0
.012
.015
.016
.019
.051*
.051*
Total
0.859
1.056
1.113
1.368
1.28*
1.31*
-------
Table 95. Treatment Level Costs on Wastewater Flow Basis
U)
en
Annual Costs ($ per 1,000 gal)
Industry Category
and Treatment Level
Category I:
Treatment Level
Treatment Level
Category II:
Treatirent Level
Treatment Level
Category III:
Treatment Level
Treatment Level
1
2
1
2
1
2
($ per gpm)
600
737
600
737
285.29
294.12
Capital
0.
0.
0.
0.
0.
0.
057
070
057
070
027
028
Depreciation
0
0
0
0
0
0
.076
.094
.076
.094
.036
.038
Operating Cost
less
0
0
0
0
0
0
Power
.336
.413
.336
.413
.033
.033
Power
0
0
0
0
0
0
.007
.008
.007
.008
.004
.004
Total
0.476
0.585
0.476
0.585
0.100
0.103
-------
FIGURE 18.
1.056
.859 r-
20
COST OF TREATMENT vs. EFFLUENT REDUCTION
CATEGORY I
40
PERCENT REMOVED
60
80
100
-------
FIGURE 19.
1.368
1.113
U)
to-
co
COST OF TREATMENT vs. LFFLUEN11 REDUCTION7
CATEGORY II
20
40
PERCENT REMOVED
B/iTEA.
BPCTCA
100
-------
FIGURE 20.
00
COST OF TREA07CNT vs. EFFLUENT REDUCTION
CATEGORY III
80
100
PERCENT RE?WVED
-------
INCREMENTAL COSTS OF ACHIEVING LEVELS OF TREATMENT TECHNOLOGY
The cost of achieving the various levels of treatment technology in the
industry will vary from plant-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 scrubber 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 shewn in Table 94 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 additional 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 scrubber 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 percent 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 would be
$5,081/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 percent 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.
ENERGY AND NON-WATER QUALITY ASPECTS
There are significant energy and nonwater quality aspects to the
selection and operation of treatment systems. These may be considered
as land requirements, air and solid waste aspects, by-product
potentials, and energy requirements.
139
-------
Land acquirements
One of the important aspects in the selection of wastewater treatment
systems in this industry is the land required for water treatment
systems. Many plants in this industry have extensive land areas
available for such uses and may elect to use this land, and existing
lagoons, as part of their water treatment system. Other plants might
possibly not have land readily available and would have to select
alternative treatment systems such as the use of filters for sludge
dewatering, rather than sludge lagoons, for this reason alone.
Airland Solid Viastes
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 landfilling in a
sealed site, or encapsulation in concrete or polymers. There 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. The potential for
such recovery methods is probably very limited, since this refining
process is not a common operation. Although there has been some
discussion in the industry of reusing the particulates collected in
baghouses as part of the furnace charge, to the best of our knowledge
this has not actually been attempted as yet.
Slag concentration is used at a number of plants to recover metal values
and as a byproduct, 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
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 not add to
potential water pollution, since the particulates replace ore in an
140
-------
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.
Power requirements for waste water treatment systems are generally low.
Power uses range from less 0.07 percent to 1.3 percent of the power used
in the smelting furnaces. The higher figure is fcr 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. This compares with the use of about 10
percent of the productive power for operation of high-energy scrubbers
for air pollution control.
Monitoring
For the purpose of writing a permit, one would need to know historical
production figures for the plant. These may be in the form of tonnage
of the various products (broken down by product, and also by the type of
furnace and air pollution control system), or else in the form of power
consumption, broken down by the type of furnace and air pollution
control system.
For example. Plant X may have produced 200 tons per day of HC
ferrcmanganese in open electric furnaces with wet scrubbers, 150 tons
per day of silicomanganese in a covered electric furnace with a wet
scrubber, and 350 tons per day of 50 percent ferrosilicon in furnaces
with dry or no air pollution control equipment. These tonnage figures
may then be converted, using Table 18, into power consumption figures.
As another example. Plant Y may have used 110 mwhr/day in open furnaces
with wet air pollution control systems, 290 mwhr/day in a covered
furnace with a wet scrubber, and 480 mwhr/day in furnaces with
baghouses.
An alternative for plants which do not posses historical production
data, would be the use of capacity figures, such as the furnace or
transformer rating.
Historical data covering a year's time would probably be necessary,
although in the case of a plant which has several furnaces out of
operation, but plans to use these in the future, a longer period might
be necessary.
141
-------
Once the permit has been issued, the plants would need to know the
appropriate flows and concentrations of the pollutant parameters so that
the pollution load from the plant may be reported as Ib/day.
142
-------
SECTION IX
BEST PRACTICABLE CONTROL TECHNOLOGY CURRENTLY AVAILABLE,
GUIDELINES AND LIMITATIONS
INTRODUCTION
The effluent limitations which must te 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 sutcategory.
Consideration must also be given to:
a. The total cost of application of technology in relation to the
effluent reduction benefits to be 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;
f. non-water quality environmental impact (including energy
requirements).
Also, Best Practicable Control Technology Currently Available emphasizes
treatment facilities at the end of a manufacturing process but includes
the control technologies within the process itself when the latter are
considered to be normal practice within an industry.
A further consideration is the degree of econoiric and engineering
reliability which must be established for the technology to be
"currently available." As a result of demonstration projects, pilot
plants and general use, there must exist a high degree of confidence in
the engineering and economic practicability of the technology at the
time of commencement of construction or installation of the control
facilities.
Definition of what constitutes 'best practicable1 technology for many
industries involves, at first, a general review of the industry to
determine the best technologies being practiced in the industry. Then,
after closer review and investigation of these technologies, the 'best
practicable' technology would be assessed as the average of the best,
1U3
-------
though not necessarily the best technology, after taking into account
information relating to other factors spelled out in the Act. In those
industries where present treatment is uniformly inadequate, a higher
degree of treatment than is presently practiced may be required, based
on a comparison with existing treatments for similar wastes in other
industries. Factors for determining the 'best available' technology are
similar, except that rather than assessing the average of the best, the
focus is on the very best technology currently in use or demonstrably
achievable.
Under thio analysis of the statutory standard, it is the opinion of the
Agency that it is not necessary that 'best practicable' technology be
currently in use as a single treatment.
EFFLUENT REDUCTION ATTAINABLE THROUGH THE APPLICATION OF BEST
PRACTICAELE CONTROL TECHNOLOGY CURRENTLY AVAILABLE (BPCTCA)
Based upon the information contained in Sections III through 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 1 technologies to the
various industry categories as shown in Table 96.
Table 96. BPCTCA EFFLUENT GUIDELINES TREATMENT BASIS
Industry Category Treatment Basis
I Chemical treatment, clarifier-flocculators,
recirculation at the scrubber
II Chemical treatment, clarifier-flocculators
III Clarifier-flocculators
Category I
New, larger open furnaces have generally 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 recirculation
at the scrubber and this lowered volume is that to be treated for
discharge. The costs here would be those given in Tables 94 and 95,
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 or similar
industries. 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 so.ne 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.
Although the technology is not in use at any one plant, portions are in
use at various 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 conmonplace. 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.
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 cormon 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 is proposed.
Power consumption for treatment is about 1 percent of that used in the
furnaces.
The effluent limitations here apply to measurements taken at the outlet
of the last waste water treatment process unit.
1U5
-------
The effluent loads, together with estimated costs applicable to the Best
Practicable Control Technology Currently Available Guidelines and
Limitations are summarized in Table 97.
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 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 30 day average load of suspended solids would be
calculated by Category as follows:
Category I: (30 X 24) mwhr/day X 0.352 Ibs/mwhr = 254 Ibs/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 Ib/day
Category III: 10 ton/hr X 24 hr/day X 2.659 Ib/ton processed = 638 Ib/day
Total plant load, Ib/day suspended solids = 1,065 Ibs/day
(4,84 kg/day)
146
-------
Table 97. BEST PRACTICABLE CONTROL TDCliNOinGY CURRUJTLy AVAILABLE
GUIDEUN1S AND LIMITATIONS
Suspended Solids
Total Cliromium
Hexavalent
Chromium
Manganese
Total Cyanide
Phenol
pli
CATEGORY I
30 Day Average 24 hr Maximum
kg/mwhr
.160
.0032
.0003
.032
Ib/nwhr
.352
.007
.0007
.070
kg/ira.'hr
.319
.006
.0006
.064
lb/r,whr
.703
.014
.0014
.141
. CATEGORY II*
30 Day Average 24 hr Maximum
6.0 - 9.0
kg/mwhr
.209
.004
.0004
.042
.002
.004
Ib/mwlir
.461
.009
.0009
.092
.005
.009
kg/r.iwhr
.419
.008
.0008
.084
.004
.006
Ib/hwhr
.922
.018
.0018
.184
.009
.013
6.0 - 9.0
CATK3ORY III
30 Day Average 24 lir Maxiiuum
kg/kkg Ib/ton kg/kkgIb/ton
1.330 2.659 2.659 5.319
.026 .053 .053 .106
.266 .532 .532 1.064
G.O - 9.0
Cost Iter,i
Investnent
Capital.Costs
Depreciation
Operating Costs
Lesn r-ov:er
Power Costs
Total Operating
Costs
$/miv'hr
17,143
0.103
0.138
0.606
0.012
0.859
22,222
0.134
0.178
0.785
0.016
1.113
$/ton/day
2,526
0.344
0.459
0.421
0.051
1.2S
*For nonelectric furnace smelting operations, read units as kg/kkg (Ib/ton), rather than kg/nwhr (Ib/mwlir), and imltiply
the metric unit limitations by 3.3 and the Qiglish unit limitations by 3.0.
-------
-------
SECTION X
BEST AVAILABLE TECHNOLOGY ECONOMICALLY ACHIEVABLE,
GUIDELINES AND LIMITATIONS
INTRODUCTION
The effluent limitations which must be achieved by July 1, 1983 are to
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 within the industry
category or by technology which is readily transferable from 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-use, 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 BEST 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
149
-------
reduction attainable through the application of best available
technology economically achievable is the application of the levels of
treatment described in section VII as Level 2 to the various industry
categories as shown in Table 98.
Table 98. BATEA EFFLUENT GUIDELINES TREATMENT BASIS
Industry Category Treatment Basis
I Chemical treatment, clarifier-flocculators,
sand filters, recirculaticn
II Chemical treatment, clarifier-
flocculators, sand filters, recirculation
III Clarifier-flocculators, recirculation
These guidelines have been selected on the basis of the following
considerations and assumptions.
Category I
The effluent load reduction above Level 1 is primarily due to the
effluent reduction attained through recirculation of the 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. Additionally, some plants may not find baghouses to be the
most efficient or economical means for reduction of air emissions.
Category II
Again, load reduction above Level 1 is due primarily to the reduction in
effluent volume attained by recirculation. Although Plant C was
achieving 97 percent 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.
150
-------
Category III
Since water is used only as a transport or cooling 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
minimal discharge (less than 2 percent) of total circulation is
practiced at one plant. However, since differing conditions may require
greater blowdown rates, a higher blowdown rate has been used to
calculate the guidelines. It is intended that removal of suspended
solids be accomplished prior to recirculation, so that valves, etc. will
not be unduly abraded. The engineering problems are minimal, requiring
only recirculation pumps and clarifier^flocculators close to the slag
processing equipment.
Summary
The suggested Guidelines present no particular problems in
implementation from an engineering aspect and require no process
changes. Water reuse and good housekeeping are emphasized. 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
1.3 percent 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 control of
runoff due to storm water for the 1983 standards for existing plants.
Such 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 the
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 99.
151
-------
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 t.he effluent limits from the plant as a whole. 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 97 Ib/day (U4 kg/day), rather
than 1,065 Ib/day.
152
-------
Table 99 BEST AVAILABLE TECHNOLOGY ECONOMICALLY ACHIEVABLE
GUIDELINES AND LIMITATIONS
Suspended Solids
Total Chromium
Hexavalent
Chromium
Total Cyanide
Manganese
Phenol
pH
Cost Item
Investment
Capital Costs
Depreciation
Operating Costs
Less Power
Power Costs
Total Operating
Costs
CATEGORY I
30 Day Average 24 hr Maximum
kg/mwhr Ib/mwhr kg/mwhr Ib/mwhr
.012 .026 .024 .052
.0004 .0009 .0008 .0017
.00004 .0001 .00008 .0002
.0039 .0086 .008 .017
6.0-9.0
$/mw $/mwhr
21,063
0.127
0.169
0.745
0.015
1.056
30 Day
kg/mwhr
.016
.0005
.00005
.0003
.005
.0002
v/mw
27,303
CATEGORY II*
Average 24 hr Maximum
Ib/mwhr kg/mwhr Ib/mwhr
.035 .032 .071
.0012 .001 .002
.0001 .0001 .0002
.0006 .0005 .001
.012 .011 .023
.0005 .0004 .0009
6.0-9.0
$/mwhr
0.165
0.219
0.965
0.019
1.368
CATEGORY III
30 Day Average 24 hr Maximum
kg/kkg Ib/ton kg/kkg Ib/ton
processed processed processed processed
.136 .271 .271 .542
.0027 .0054 .0054 .011
.027 .054 .054 .108
,6.0-9.0
$/ton/yr $/ton
2,604
0.357
0.485
0.421
0.051
1.31
*For non-electric furnace smelting operations, read units as kg/kkg (Ib/ton), rather than kg/mwhr (Ib/mwhr) and multiply
the metric unit limitations by 3.3 and the English unit limitations by 3.0.
-------
-------
SECTION XI
NEK 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 must be considered. The end result is to identify
effluent standards achievable through the use of improved production
processes (as well as control technology). A further determination
which must be made for new source performance standards is whether a
standard permitting no discharge of pollutants is practicable.
Consideration must also be given to:
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 and mixes of raw
materials;
e. use of dry rather than wet processes;
f. 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 owned activated sludge or trickling filter 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 STANCARDS
Based upon the information contained in section III through VIII of this
report, a determination has been made that the degree of effluent
155
-------
reduction attainable by new sources is the same achieved by application
of the levels of treatment described in Section X and as shown in Table
100.
Table 100. NEW SOURCE PERFORMANCE STANDARDS BASIS
Industry Category Treatment Basis
I Chemical treatment, clarifier -
flocculators, sand filters, recirculation.
II Chemical treatment, clarifier -
flocculators, sand filters, recirculation.
Ill Clarifier-flocculators, recirculation
These performance standards have been selected on the basis of the
following assumptions and considerations:
Category I
Although baghouses may be used for air pollution control, because of
energy, efficiency and cost considerations some plants may elect to use
various 'wet* systems, such as steam/hot water scrubbers or
electrostatic precipitators. Therefore, the treatment specified for
BATEA is that which will minimize waste discharge for those plants
choosing to utilize wet air pollution control systems.
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
specified for EATEA, Category II appears to be that which will minimize
waste discharge.
Category III
Some plants may be able to achieve no discharge of pollutants from slag
processing operations by discharging blowdown into closed lagoons, where
the blowdown will be evaporated. However, due to varying soil
characteristics, other plants, if attempting to use such techniques,
156
-------
would have leaching to ground water. Sealed lagoons may not be
practicable for all plants, and additionally, may require large land
areas. Therefore, the BATEA treatment is selected as the basis for
limitations from new sources.
SUMMARY
The effluent leads, together with estimated costs, applicable to the New
Source Performance Standards are summarized in Table 101.
For the new source performance standards, it should be additionally
specified that all measurements taken 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-off 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. These
standards should be applied by the "building block" approach, as
discussed in section IX. If the hypothetical plant of that section were
a new source, the permissible suspended solids discharge would be 97
Ib/day (4U kg/day).
PRETREATMENT STANDARDS
The raw wastes from the three categories included in this document are
all generally high in metals (manganese and chromium (total and
hexavalent)), as well as suspended solids. The wastes from Category II
additionally contain cyanide and phenols. The metals are of particular
concern, if the wastes are discharged directly to publicly owned
treatment systems, since they tend to pass through such treatment works,
essentially untreated or removed. The other parameters are of less
concern, since (in the concentrations found in the typical raw waste in
this industry), they will be treated or removed by the municipal system,
and should, for this industry, be classified as "compatible pollutants."
The metals, however, fall under the general classification of
"incompatible pollutants," and therefore, a determination has been made
that the wastes from these three categories should be treated to the
level of best practicable technology (for existing sources) and to the
level of the new source performance standards (for new sources).
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 navigable waters),
157
-------
Shall be the standard set forth in Part 128, 40 CFR, except that the
ptetreatment standard for incompatible pollutants shall be the standard
of performance for new sources of that subcategory. If the publicly
owned treatment works is committed, in its NPDES permit, to remove a
specified percentage of any incompatible pollutant, the pretreatment
standard applicable to users of such treatment works shall be
correspondingly reduced for that pollutant.
158
-------
Table 101 NEW SOURCE PERFORMANCE STANDARDS
Suspended Solids
Total Chromium
Hexavalent
Chromium
Total Cyanide
Manganese
Phenol
pH
Cost Item
Investment
Capital Costs
Depreciation
Operating Costs
Less Power
Power Costs
Total Operating
Costs
CATEGORY I
30 Day Average 24 hr Maximum
kg/mwhr Ib/mwhr kg/mwhr Ib/mwhr
.012 .026 .024 .052
.0004 .0009 .0008 .0017
.00004 .0001 .00008 .0002
.0039 .0086 .008 .017
6.0-9.0
$/mw $/mwhr
21,063
0.127
0.169
0.745
0.015
1.056
30 Day
kg/mwhr
.016
.0005
.00005
.0003
.005
.0002
$/mw
27,303
CATEGORY II*
Average 24 hr Maximum
Ib/mwhr kg/mwhr Ib/mwhr
.035 .032 .071
.0012 .001 .002
.0001 .0001 .0002
.0006 .0005 .001
.012 .011 .023
.0005 .0004 .0009
6.0-9.0
$/mwhr
0.165
0.219
0.965
0.019
1.368
CATEGORY III
30 Day Average 24 hr Maximum
kg/kkg Ib/ton kg/kkg
processed processed processed
.136 .271 .271
.0027 .0054 .0054
.027 .054 .054
6.0-9.0
$/ton/yr $/ton
2,604
0.357
0.485
0.421
0.051
1.31
Ib/ton
processed
.542
.011
.108
*For non-electric furnace smelting operations, read units as kg/kkg (Ib/ton), rather than kg/mwhr (Ib/mwhr) and multiply
the metric unit limitations by 3.3 and the English unit limitations by 3.0.
-------
-------
SECTION XII
ACKNOWLEDGEMENTS
The Environmental Protection Agency would like to thank Dr. H.C. Bramer
and Messrs. E. Shapiro and N. Elliott of Datagraphics, Inc. for their
aid in the preparation of this report. Thanks are also given to the
sampling crews (Messrs. D. Eramer, D. Riston, C. Caswell, E. D. Escher,
E. Brunell, et al). Special thanks is also given to Ms, Darlene Speight
of Datagraphics, Inc., Mrs. Nancy Zrubek and Ms. Patsy Williams of EPA
for their long, late hours spent in the typing and retyping of this
report.
The author would like to thank her associates in the Effluent Guidelines
Division, particularly Messrs. Edward Dulaney, Walter J. Hunt, Ernst P.
Hall, and Allen Cywin for their helpful suggestions and assistance.
Thanks also are expressed to Messrs. George A. Watson and Arthur M.
Killan of the Ferroalloys Association for their valuable assistance.
Acknowledgement and appreciation is extended tc 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.; R.D. Turner and W.A. Witt of
Chromium Mining and Smelting Corporation; C.G. Adler and E.W. Batchelor
of Foote Mineral Company; F. Krikau and J.C. Cline of Interlake, Inc.;
and C.F. Seybold, M. Evans, and L. Risi of Shieldalloy.
Appreciation is also expressed to Mr. H'. Rathman who acted as a
consultant to Datagraphics, Inc. and provided invaluable 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 of the EPA Working Group/Steering
Committee for their advice and assistance. They are: Messrs. A.
Brueckmann, S. Davis, M. Dick, T. Powers, R. Zener, E. Lazar, Dr. H.
Durham and Walter J. Hunt.
161
-------
-------
SECTION XIII
REFERENCES
1. Compilation of Air Pollutant Emission Factors, U.S. Environmental
Protection Agency, Office of Air Programs, February, 1972 (N.T.I.S. No.
PB-209 559).
2. Sherman, P. R. & Springman, E. R., "Operating Problems with High
Energy Wet Scrubbers en Submerged Arc Furnaces", a paper presented at
the American Institute of Metallurgical Engineers Electric Furnace
Conference, Chicago, Illinois December, 1972
3. Scherrer, R. E., "Air Pollution Control for a Calcium Carbide
Furnace", A.I.M.E. Electric Furnace Proceedings, Volume 27, Detroit,
1969, pages 93-98
4. Seybold, Charles F., "Pollution Control Equipment for Thermite
Smelting Processes", A.I.M.E. Electric Furnace Proceedings, Volume 27,
Detroit, 1969, pages 99-108
5. Person, R. A., "Control of Emissions frcm Ferroalloy Furnace
Processing", A.I.M.E. Electric Furnace Proceedings, Volume 27, Detroit,
1969, pages 81-92.
6. Retelsdorf, H. J., Hodapp, E., & Endell, N., "Experiences with an
Electric Filter Dust Collecting System in Connection with a 20-MW
Silicochromium Furnace", A.I.M.E. Electric 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. Dehuff, J. A., coppolecchia, V. D., & Lesnewich, 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,
163
-------
12. "Water Use in Manufacturing", 1967 Census of Manufactures, U.S.
Department of Commerce, Bureau of the Census, ME 67 (1) -7, April, 1971,
361 pages.
13. Ferrari, Renzo, "Experiences in Developing an Effective Pollution
Control System for a Submerged Arc Ferroalloy 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 F. Rissman of General Technologies
Corporation - Trip Report from the Astabula, Ohio plant of Union Carbide
Corporation, February 14, 1973.
16. Braaten, O. and Sandberg, C., "Progress in Electric Furnace
Smelting of Calcium Carbide and Ferroalloys", 5th International Congress
on Electro-Heat, 7 pages.
17. Scott, J. W., "Design of a 35,000 K. W. High Carbon Ferrochrome
Furnace Equipped with an Electrostatic Precipitator", The Metallurgical
Society of A.I.M.E., paper No. EFC-2, 9 pages.
18. "A Study of Pollution Control Practices in Manufacturing Industries
- Part 1 - Water Pollution Control", Dun & Bradstreet, 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, 1973, (Unpublished).
21. Mantell, C. L., "Electrochemical Engineering," McGraw-Hill Book
Company, Inc., 4th 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, Walter 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.
164
-------
25. "Minerals Yearbook - 1970", United States Bureau of Mines, pages
513-518.
26. "Minerals Yearbook - 1967", United States Bureau of Mines, pages
499-506.
27. "A New Process for Cleaning and Pumping Industrial Gases - The
ADTEC System", Aronetics, Inc., Tullahoma, 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 45-51.
31. Eckenfelder, W. W., "Water Quality Engineering", Barnes and Noble,
New York (1970).
32. "Air Pollution Control Engineering and Cost Study of the Ferroalloy
Industry" (Draft Report), 1973, U. S. Environmental Protection Agency,
Office of Air and Water Programs, Washington, B.C. (Unpublished).
33. "Draft Development Document for Effluent Limitations Guidelines and
Standards of Performance, Alloy and Stainless Steel Industry",
Datagraphics, Inc., Pittsburgh, PA, 1974.
34. Rudolfs, Willem, "Industrial Wastes, Their Disposal and Treatment,"
Reinhold Publishing Corp., 1953.
35. "Development Document for Proposed Effluent Limitations Guidelines
and New Source Performance Standards for the Steel Making Segment of the
Iron and Steel Manufacturing Point Source Category," United States
Environmental Protection Agency, February 1974, EPA 440/1-73/024.
165
-------
-------
SECTION XIV
GLOSSARY
Blocking chrome - A high 10-12 percent silicon grade of high carbon
(HC) Ferrochromium, used as an additive in the making of chromium steel
where it 'blocks' (i.e., stops) the reaction in the ladle,
Charge Chrome - A grade of HC ferrochromium, so called because it forms
part of the charge in the making of stainless steel.
Charging - The process by which raw materials ("charge") are added to
the furnace.
Chrome ore - lime melt A melt of chromium ore and lime produced in an
open arc furnace and an intermediate in the production of low carbon
(LC) ferrochromium.
Covered furnace - An electric furnace with a water-cooled cover over the
top to limit the introduction of air which would burn the 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 withoxygen 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
chargeexposed to the atmosphere, whereby the reaction gases are burned
by the inrushing air.
167
-------
Open arc furnace -» Heat is generated in an open arc furnace by the
passage of an electric arc, either between two electrodes or between one
or more electrodes and the charge. The arc furnace consists of a
furnace chamber and two or more electrodes. The furnace chamber has 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 dia.neters up to about 130 cm (51 in.) . These electrodes come in
sections with threaded ends, and are added to the electrode column.
Reducing Agent - Carbon bearing materials, such as metallurgical coke,
low volatile coal, and petroleum coke used in the electric furnace to
provide the carbcn which combines with oxygen in the charge to form
carbon monoxide, thereby reducing the oxide to the metallic form.
Self-baking electrode - The electrode consists of a sheet steel casing
filled with a paste of carbonaceous material quite similar to that usod
to make prebaked amorphous carbon electrodes. The heat from the passage
of current within the electrode and the heat from the furnace 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, or by heating and pressing, so that
certain constituents of the particles coalesce, fuse, cr otherwise bind
together. This may occur in the furnace itself, in which 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.
Submerqed-arc^furnace - In ferroalloy reduction furnaces, the electrodes
usually extend to a considerable depth into the charge, hence such
furnaces are called "submerged-are furnaces". This name is used for the
furnaces whose load is almost entirely of the resistant type.
Tapping - This term is used in the metallurgical industries for the
removal of molten metal frcm furnaces, usually by opening a taphole
located in t he lower portion of the furnace vessel.
168
-------
Vacuum furnace - A furnace in which the charge can be brought to an
elevated temperature in a high vacuum. The high vacuum provides an
almost completely inert enclosure where the process of reduction and
sintering can occur.
-------
-------
-------
-------
-------
------- |