-------
cascading of process waste water is practiced to varying
extents.
For primary lead facilities geographically located in areas
of net evaporation, the effluent limitation and standard of
performance, based upon current industry practices, is no
discharge of process waste water pollutants to navigable
waters. A storm water runoff discharge provision _is
proposed for these facilities to alleviate potential
problems associated with this source of waste water. For
primary lead facilities geographically located in areas of
net precipitation, a discharge of process waste water is
permitted. The amount of pollutant discharge, as a function
of lead production, was derived as a product of process
waste water flow volume per unit of production and pollu-cant
concentration, after application of liming and settling.
Since control routes for the minimization of acid plant
blowdown by means of reuse and recycle, producing smaller
values than indicated by the best practicable technology,
are questionable and since additional sulfur oxide permanent
control may be required of primary lead smelters, which
SSSlf increase ?he magnitude of the blowdown, the best
available technology economically achievable is considered
to be identical to the recommended best practicable control
technology currently available. New source performance
standards for air pollution will probably require permanent
sulfur oxide control of the entire sinter machine offgas by
means of weak-strand gas recirculation. For this reason,
the best demonstrated control technology is considered to be
identical to the proposed best practicable control
technology currently available.
It has been estimated that for the existing plants to
achieve the levels cf control of process waste water
pollutants recommended for July 1, 1977 and July 1. 1983,
the required capital cost and annual operating cost would
total $1,275,000 and $570,700, respectively.
-------
SECTION II
RECOMMENDATIONS
n arof^ facillties geographically located
i«r«ter|o^tt.nSaPSrt^igSledl'2|t'SI °* ^«~
provisions to this regulation follow- Waters' sPecial
SsEL'L-F"
-------
lEffluent_limitation§
Effluent
characteristic
Maximum for
any 1 day
Average of daily
values for 30
consecutive days
shall not exceed
Metric units__(mg/ll
TSS
Cd
Pb
Zn
pH
50
1.0
1.0
10
25
0.5
0.5
5
Within the range 7.0 to 10.5
English units (ppm)
TSS
Cd
Pb
Zn
ES.
50
1
1
10
.0
.0
in the r
25
0.5
0.5
5
ange 7.0 to 10.5
For primary lead facilities geographically located
in areas of net precipitation:
lEfJ[lu.ent_limitation£
Effluent
characteristic
Maximum for
any 1 day
Average of daily
values for 30
consecutive days
shall not exceed
Metric units (kilograms per 1000 kg
of product)
TSS
Cd
Pb
Hg
Zn
pH
0.042
0.0008
0.0008
8.0x10~6
0.008
0.021
0.0004
0.0004
4.0x10~6
0.004
Within the range 7.0 to 10.0
-------
English units (pounds per 1000 Ib
of product] ____
°-OZ42 0.021
0.0008 0.0004
0.0008 0.0004
8.0x10-6 4.0x10-6
0.004
7 . 0 _tg_10 . 0
?{!* h!SJ availabif technology economically achievable and
the best available demonstrated control technology
identical' to^f^ T^5' °r °ther alternatives 1^4
identical to the best practicable control technoloav
andrestan^ilab^ ?6 CO^S^^^ effluent lirJtSons
and standards of performance are identical to the effluent
thS1^ i°nS ^lde^nes established after the application of
the best practicable control techr.clcgy currently available.
The rationale for these effluent limitations and standards
of performance are contained in Sections IX, X, and XI of
this development document.
-------
SECTION III
INTRODUCTION
ft tha?. Publi=ly <**>ea treatmen workf,
" s^sariStSLS' -r -ssssr -,«
Administrator pursuant to Section 304 (b) of thS Act.
301Jb) .S80 re^uires ^e achievement by not later
technology economically achievable which will rlsui? i
reasonable further progress toward the goal of eliminati
attainable through the appliation of
salting subcategory of 'tL^onfer^oaa etals ca'tegorf.
-------
Methods Used for Development^o£_gffluent
Limitations Guidelines and Standards of Performance
The guidelines and standards of performance that are
recommended in this document for the primary lead industry
were developed by analyzing information on the industry and
its current water management practices, as well as
information on the practices in related industries.
Initially, a literature search was made of statistical
abstracts, monographs, and journal articles in order to
assemble data on the companies in the primary lead industry.
From this information, an inventory was compiled for each
facility, covering location, age, climate, number of
employees, operations conducted, production figures, air
pollution control systems employed, and future plans. This
inventory provided an overview upon which later data
acquisitions could be built and from which the need for
industry subcategorization could be assessed.
There are seven plants or properties in the United States
presently engaged in lead smelting and/or refining. A
representative of each of these was contacted by telephone
or letter to acquire information on production operations
and waste water treatment methods. Assistance was provided
by members of the Water Pollution Control Subcommittee of
the American Mining Congress in obtaining data from the
firms they represented. Several state water pollution
control offices and EPA regional offices contributed
information on the primary lead facilities under their
jurisdiction.
General information from firms was obtained by telephone
conversations with each company. Information regarding
process equipment, water usage, waste water outfalls,
treatment practices, treatment costs, water analyses, and
storm water runoff was requested during these conversations.
Plant visits were made to six sites. The sites selected for
visits represented a variety of climates, industry
processing practices, ore types, and water management
methods.
Additional data for four plant sites were obtained from the
Corps of Engineers Permits to Discharge under the Refuse Act
Permit Program, (RAPP). These included (in varying degrees
of detail) composition, temperature, and volume of intake
and effluent water, plus a general description of waste
water treatment. Some analysis data was also provided on
the questionnaire completed by several companies.
-------
Two plant sites were visited in order to sample and navz^
Sf^ lnter"al and °»ttall streams. The sJtes werl
selected in order to obtain the widest variety of streams J?
unitaoStal^ti0n' /° deVel°P 8P«"ic information regarding
unit operations and waste characterization, to verify the
treatment. **' ^ "° dete™ine ^e effect of wastewater
The data obtained from the literature and the field were
prod^d and^hfa^ J^.80"?68 ™* -lames of wLle wltJr
?£* f • u quantities of constituents contained in
the discharge. on the basis of this analysis the
constituents of waste water considered to be pollutfonally
significant were identified. p^-tj-uxionaiiy
On ^COntro1. and treatment technologies
ifo °r Un r considerati°n were supplemented by
information covering control technologies from other
industries, which might be applicable to the treatmen^and
control of waste water from the primary lead industry
Consideration was given to both inplant and end-*of-procel;
technologies and to applications of the effluent from ?he
various production operations. For each of the control or
treatment technology candidates, the resultant was?e Sater
constituents were determined and the limitations and
were
^^^
All of the information developed was evaluated in order to
^^Hi*1^ leV6lS °f tech«clogy constitute the bes?
liable ^T^1 technolo5Y currently available, the best
J !^i S technology economically achievable, and the best
available demonstrated control technology.
classified under SIC 3356, and are not subjec? to Ihe
1031 UeaSVS d.Standards set f°^h by this document. si?
1031 (Lead and ^mc Ores) describes establishments which are
-------
primarily engaged in the mining, milling, or otherwise
preparing lead ores, zinc ores, or lead-zinc ores. These
establishments are also not subject to the proposed
regulations derived from this document.
The primary lead industry, consisting of six domestic lead
smelters and five refineries ranks fifth in tonnage of
United States metals produced, after iron, aluminum, copper
and zinc. The geographic distribution of these facilities
is shown in Figure 1 and tabulated in Table 1. Four of the
six smelters have on-site refineries, while two produce lead
bullion, which is shipped to a lead refinery.
Primary lead in the United States is recovered entirely from
sulfide ores, which are associated with other minerals,
chiefly zinc, copper, and silver. In addition to zinc and
copper, associated byproducts in seme of the more complex
ores include economically significant amounts of gold,
silver, cadmium, bismuth, indium, and antimony.
There are approximately 48 mines that mine ore containing
important percentages of lead and 31 concentrating
facilities, which supply lead concentrates to the six
smelters. Some lead concentrates are imported from as far
as Australia. In 1971, the leading mines, all in Missouri,
produced 72 percent of total domestic mine production, the
10 leading mines produced 85 percent, and the 25 leading
mines contributed 98 percent. In this same year, mines west
of the Mississippi produced almost 99 percent of the lead
ores, with the most important lead producing areas being
southeastern Missouri, Shoshone County in Northern Idaho,
the area just south of Salt Lake City in north central Utah,
and the Upper San Miguel region in southwestern Colorado.
The 1971 lead mine production by states is given in Table 2.
Lead consumption in the United States, by product, in 1970
and 1971, is shown in Table 3.
10
-------
(S) = Smelter only.
(R) = Refinery only.
(S 4- R) = Smelter and refinery.
Figure 1. Geographic locations of domestic primary lead smelters and refineries.
-------
(1-5)
TABLE 1 • LEAD SMELTERS AND REFINERIES
Company Location
American Smelting and Glover,
Refining Company Missouri
Ditto East Helena,
Montana
_, " El Paso,
^ Texas
" Omaha,
Nebraska
Annual Tons
of Lead
Containing
Material
Treated 1972
159,600
192,000
not reported
136,000
First
Year Of
Operation
1968
1888
1887
1870
Raw Materials
Used
Lead Cone.
Waela Residue
Lead Residues
Lead Cone.
Siliceous Ores
Zinc Residue
Lead Bullion
Secondary 'Lead
Slag Acid
Treatment Plant
None None
Slag None
Fuming
Furnace
Slag None
Fuming
None None
Products
Refined Lead
Copper Dross
Retort Bullion
Lead Bullion
Soda Ash Matte
Soda Ash Speiss
Lead Baghouse Dust
Zinc Fume
Lead Bullion
Zinc Fume
Refined Lead
Antimonal Lead
Solder
Bunker Hill Co.
St. Joe Minerals
Missouri Lead
Operating Co.
Kellogg,
Idaho
550,000
Herculaneum, 336,000
Missouri
Boss,
Missouri
192,500
1918
1892
1968
Lead Cone.
Lead Cone.
Lead Cone.
Slag
Fuming
None
None
Misc. Lead Alloys
Bismuth
Copper Matte
Sodium Telluride
Slag,
300 TPD Refined Lead,
Gold, Silver,
Antimony
300 TPD Refined Lead,
Silver Bullion,
Copper Matte
225 TPD Refined Lead
Copper Matte
Dross
Silver Bullion
-------
TABLE 2. MINE PRODUCTION OF RECOVERABLE LEAD
IN THE UNITED STATES, BY STATED
(Short Tons)
State
Alaska
Arizona
California
Colorado
Idaho
Illinois
Kansas
Kentucky
Missouri
Montana
Nevada
New Mexico
New York
Oklahoma
Oregon
Soiuth Dakota
Utah
Virginia
Washington
Wisconsin
Other States
Total
1967
__
4,771
1,735
21,923
61,387
2,384
1,031
845
152,549
898
1,500
1,827
1,653
2,727
—
53,813
3,430
2,762
1,596
--
316,931
1968
W
1,704
4,001
19,778
54,790
1,467
1,227
W
212,611
1,870
863
1,363
1,396
2,387
W
45,205
3,573
5,655
1,126
140
359,156
1969
2
217
2,518
21,767
65,597
791
395
—
355,452
1,753
1,420
2,368
1,686
605
(1)
1
41,332
3,358
8,649
1,102
—
509,013
1970
__
285
1,772
21,855
61,211
1,532
80
--
421,764
996
364
3,550
1,280
797
(1)
3
45,377
3,356
6,784
761
__
571,767
1971
....
859
2,284
25,746
66,610
1,238
--
—
429,634
615
111
2,971
877
--
—
38,270
3,386
5,177
752
20
578,550
W Withheld to avoid disclosing individual company confidential data;
included in "Other States".
(1) Less than 1/2 unit.
13
-------
TABLE 3. LEAD CONSUMPTION IN THE UNITED STATES, BY PRODUCT
Product
Metal products:
Ammunition
Bearing metals
Brass and bronze
Cable covering
Calking lead
Casting metals
Collapsible tubes
Foil
Pipes, traps, and bends
Sheet lead
Solder
Storage batteries:
Battery grids, posts, etc.
Battery oxides
Terne metal
Type metal
Total
Pigments:
White Lead
Red Lead and litharge
Pigment colors
Other^1'
Total
Chemicals :
Gasoline antiknock additives
Miscellaneous chemicals
Total
Miscellaneous uses:
Annealing
Galvanizing
Lead plating
Weights and ballast
Total
Other, unclassified uses
(2)
Grand Totalv '
1970
72,726
16,328
18,927
50,772
34,608
7,498
10,913
5,521
17,888
21,050
69,707
283,451
310,002
1,038
24,476
944,905
5,936
77,215
14,407
1,178
98,736
278,505
623
279,128
4,161
1,792
400
16,184
22,537
15 T 246
1,360,552
1971
87,567
16,285
20,044
52,920
29,993
7,281
10,041
4,417
18,174
27,607
70,013
322,236
357,567
1,409
20,812
1,046,366
4,731
61,838
13,916
773
81,258
264,240
401
264,641
4,068
1,395
582
17,453
23,498
15T751
1,431,514
(1) Includes lead content of leaded zinc oxide and other pigments.
(2) Includes lead that went directly from scrap to fabricated products.
14
-------
SECTION IV
INDUSTRY CATEGORIZATION
Introduction
This section describes the scope of the primary lead
industry. Included are technical discussions of the raw
materials used, methods of production, and products
produced. Possible methods of subcategorizing this industry
into discrete units for separate waste treatment and
effluent limitations guidelines are also discussed.
Objectives of Categorization
The objective of industry categorization is to establish
recommended effluent limitations and standards of
performance, which are specific and uniformly applicable to
a given category. Categorization, therefore, involves the
identification and examination of the factors in the
industry, which might affect categorization in terms of the
recommendations to be developed.
Factors Considered
Manufacturing Process
As explained in the previous section, there are six primary
lead smelters and five primary lead refineries in the United
States. Salient characteristics of each of these
operations, including data on the number of years in
operation, annual tonnage of lead concentrates handled,
origin of concentrates, method of handling the zinc
constituent in the concentrates, method of handling SO2
offgas from the sintering machine, location of the refinery
with respect to the smelter, and annual production of
refined lead, are shown in Table 4.
The sequence of lead smelting and refining processes,
illustrated in the generalized flowsheet in Figure 2, are
charge preparation (blending of the concentrate with flux,
return products, etc), sintering, blast furnace smelting,
and the subsequent refining operation to remove and, in some
cases, recover metallic impurities. The major steps in the
production of lead will be discussed in this sequence.
Charge Preparation. In general practice, charge preparation
may involve the blending of lead concentrates with fluxes
and a variety of recycle products, such as dust from
15
-------
TABLE 4. SALIENT CHARACTERISTICS OF U.S. LEAD SMELTERS
Plant
A
B
Year
First Origin of
Operated Concentrates
1891 U.S.A.
(S.E. Mo.
ores)
1968 U.S.A.
(S.E. Mo.
Ores)
Method of
Slag Handling S02
Fuming Gas From
Plant Sinter Mach.
None; Acid plant
zinc dis-
carded in
slag
None; Acid plant
zinc dis-
carded in
slag
Refined Lead
Refinery Production
Adjacent 1000 units/year
to Smelter kkg (tons)
yes 209 (230)
yes 121 (133)
1968
1917
1888
1887
U.S.A.
U.S.A.
Canada, Peru,
Australia
U.S.A.
Canada, Peru,
Australia
U.S.A.
Canada, Peru,
Mexico
None; Spray chamber,
zinc dis- baghouse,
carded "in stack
slag
yes Acid plant
yes Spray chamber,
baghouse,
yes Spray chamber,
baghouse,
stack
yes
98
yes
No; bullion
refined at
Asarco refin-
ery in Omaha
No; bullion
refined at
Asarco refin-
ery in Omaha
121
58
56
(108)
(133)
(64)
(62)
1870
N.A.
N.A.
N.A.
N.A.
123
(136)
-------
SMI
Lead Concentrates
Flux » Char
Prepar
[—
1
Recycle
Underslze
L ~
ation
^" Sinter Fume
SECTION
1
Coke - BUgt
1 ». Furnace
t
Partial
Recycle of Sett
Refinery
Dross
Lead E
Slag
ler *
ullion
Solid!
' S02 CM
Dust
System
Slag fc Slag
Granulation
J
Water
Slag ^ Zinc Fuming
""" Furnace
Stack
tt
1
_^ Acid
Plant
• _att cr
t
Recycle
to Sinter
t
- 1 g To
Waate
p Fume to Baghouse
„ Slag to Waste
Lead
"• (ist and 2nd Co
Sulfur *|
f
[
i
ties B
t
pper By-Product
*" Reverberate
Furnace
f"*" Baghouse r *
J Softening Arsenl
cal & _, Hard Lead
». Fume
ry •• Copp
to C
to Baghouse
er Matte and Spelss
.opper Smelter
-CO , Silica Lead Oxide
Refining
•» Antimonial
; ' ; Skims ' 1 '—— *
i *— f Slag to Charge Preparation (By-Product)
So£tfinsd Lead
Zinc to Desilverizing
Lead i AIr
til t . . T
Desilve
1
REFINERY
SECTION
Zinc »— f. Desllver
'• 2
Si
rizlng (
^ Secondary
L<
i
Vaccum
^ Dezincinj?
Ca.MR • Deblsmu
Ket
tie
NaOH «• Refining
NaNO Kettle
Refined Lead
lver f llouard 1
klras Press
Sliver Skims
t
iros ^ Howard
Press
C12 Gas,
Oxidizing Flux,
Charcoal
1
Bismuth
^ Dross
sr Retort 1—
1
•» Cupel 1 •• D° re'
! 1
t
PbO(Lltharge)
Reclrculated
to B.F.
, Bismuth Metal
•y Removal, Traces of Zn, Sb , and As
(Caustic Dross to Charge Preparation)
Figure 2. Generalized flow sheet of a lead smelter and refinery.
17
-------
collection systems, fumes, slags, etc, which contain
recoverable lead and other metals. This blended mixture is
pelletized after addition of moisture (up to 1C percent) by
rolling in rotating drums, referred to as ball drums, to
form spherical pellets about 1/2 inch or more in diameter.
The pelletized concentrates are then sintered.
Sintering is done on a "sintering machine"
which, in essence, is a traveling grate furnace. Both
downdraft and updraft machines have been used in sintering
lead and zinc concentrates, but at present the latter are
more commonly used for lead sintering. Figure 3 illustrates
the general structure and function of the updraft sintering
machine. In U. S. sintering procedure, a positive pressure
of air is supplied from below the traveling grate of the
sintering machine and slightly reduced pressure is
maintained above the bed. in the operation, a layer of
pelletized charge is laid down on the bed of the sintering
machine and is ignited by downdraft burners above the bed.
The balance of the charge (up to about 40 cm (16 in) total
depth) is spread on the burning layer, and the traveling
grate then enters the updraft windbox section. Under the
effect of the applied updraft, the bed burns from the bottom
up. The total charge is sintered in the front half, called
"strong gas strand", of the sinter machine, while the rear
half, the "weak gas strand" is used for cooling of the
sintered charge.
The objectives of the sintering operation are not only to
remove sulfur as SO2 and SO3 and to eliminate, by volatili-
zation, much of the undesirable impurities such as arsenic,
antimony, and cadmium, but, equally as important, to produce
"sinter" of suitable size distribution and strength for
subsequent treatment in the blast furnace process.
At the end of the sinter machine, the sinter is then passed
through a sinter breaker (i.e., spiked rolls). This
operation breaks the sinter and sizes the material. The
oversize material (+ 2 inch) is sent to blast furnace charge
preparation. The undersize product (-2 inch) is passed
through a set of roll crushers to further reduce the sinter
in size, then cooled by water addition (usually recycled
water) and sent back to sinter feed preparation. In one
case, the sinter temperature is reduced by water sprayed
directly on the sinter strand. The sinter sizing operation
produces a considerable amount of dust, and this dust is
captured by wet scrubbers or baghouses. In either case, the
collected material is recycled back to the sinter operation.
18
-------
Gas off lake
Hood
and seal
^Working floor
A_
Windbox
cleaning chute
Dust Hopper
Air inlet
Figure 3. Cross section of a typical updraft sinter in-i rachinc.
19
-------
The sintered product fed to the blast furnace will vary in
composition depending on the primary source of lead con-
centrates. The following tabulation is an example of a
finished sinter composition.
Weight
Constituent Percent
Pb 45-50
Fe 12-13
CaO 10-11
Si02 10-12
S 1-2
Zn 4-8
Cu 0.3-3.0
Blast Furnace. The blast furnace is the primary reduction
unit in a lead smelter. By a combination of heat and
reducing gases, it separates the constituents into two
phases: molten metal and slag. The metals that are easily
reduced, such as lead, copper, silver, gold, bismuth,
antimony, and arsenic, become part of the metal phase;
whereas, metals that are not easily reduced become part of
the slag phase along with the nonmetallic elements.
The lead blast furnace is water-cooled, rectangular in
shape, 6.7 to 8.5 meters (22 to 28 feet) in length and 4.6
to 6.1 meters (15 to 20 feet) in height, and may range in
width from 1.5 to 3.0 meters (5 to 10 feet), sometimes being
tapered from 3.0 meters (10 feet) wide at the top to a
minimum width of 1.5 meters (5 feet) at the bottom. It is
vertical, generally with a thimble-top design, where the
furnace is charged on both sides at the top. Associated
facilities include materials-handling equipment and an
exhaust gas handling system, an air supply system of bustle
pipes, a conveyor system for introducing the charge, tuyeres
for the introduction of air to the charge at several levels,
and a refractory crucible structure at the bottom with
provisions for continuous or intermittent tapping of lead
bullion and slag. A general arrangement is illustrated in
Figure 4.
The charge to the blast furnace always includes sinter,
coke, and fluxing or slagging additions such as silica and
limestone, and usually includes recycled slag from
associated operations, cadmium plant residues, refinery
dross, and fume from dust-collecting equipment.
The products of the blast furnace are as follows:
20
-------
Flue to
Cooling Chamber
X
Ventilation Fan
y
[\_Control for Movable
Charge Bins
^-Granulator
\ Pump
/-Granulating
Launder
Blast Furnace
Air
Bucket
glevator
Figure 4. General arrangement of a typical blast furnace and associated facilities.
-------
(a) Lead bullion, which normally contains quantities of
copper, arsenic, antimony, or bismuth. These
impurities must be removed by further processing to
produce an acceptable lead. The lead bullion also
may contain precious metals in quantities that are
worth recovering. The composition of the lead
bullion will vary from plant to plant, but will in
general contain 95 to 99 percent lead with
impurities ranging as follows:
Copper - up to 2.5 percent,
Zinc - negligible.
Antimony - up to 2 percent,
Arsenic - up to 1 percent.
Bismuth - up to 0.03 percent.
(b) Slag which consists of iron, calcium, and magnesium
silicates, small quantities of arsenic and
antimony, and variable amounts of lead (1.5 to
about 4 percent). Where the amount of zinc in the
concentrate is sufficient, the common practice is
to treat the slag in a slag fuming furnace to
recover the zinc. In the slag fuming operation,
the slag, usually while still molten, is charged to
a zinc fuming furnace, which is commonly a
reverberatory-type furnace, with or without
additions of other zinc-bearing materials (cold
slag, other recycled drosses, dusts, etc.). The
charge is heated to a high temperature through
addition of fuel (coal) and air is blown into the
molten slag. The zinc is boiled off and oxidized
to zinc oxide dust particles, which are collected
in dust collecting equipment such as cyclones,
precipitators, dust chambers, and baghouses. Slag
after zinc fuming, or that which is discarded
without fuming, is usually granulated by impacting
a stream of the molten slag with a high pressure
water jet. The granulated slag may be dewatered
and either recycled as part of the charge materials
to the sinter process, or, depending on slag
composition and plant facilities, may be totally
discarded.
(c) Matte and speiss in some blast furnace practice.
The matte phase consisting of copper and iron
sulfides and precious metals may be formed as a
discrete liquid layer between bullion and slag. If
considerable arsenic is present in the charge,
speiss is present. These materials are usually
22
-------
sent to copper smelters or outside processors for
further treatment.
Refining Operations. In some operations where the refinery
is a considerable distance from the smelter, the first step
of the refining operation, the dressing-byproduct
reverberatory furnace decopperizing operation, is performed
at the smelter as shown in the generalized flow sheet in
Figure 2. In other cases, where the smelter is adjacent to
the refinery, the dressing operation is carried on as a
refinery function. In either case, it is always the first
step in the refining of the lead bullion. The various
industrial approaches used in domestic dressing operations
are described below.
Drossing. Dressing is performed in vessels referred to as
kettles. The kettles are generally hemispherical in shape,
up to 7.3 meters (24 feet) in diameter, and are constructed
of welded steel plate up to 3.8 centimeters (1-1/2 inches)
thick, holding up to 227 kkg (250 tons). The kettles are
gas heated with external refractory brick insulation.
Permanent auxiliary equipment for stirring, skimming,
transfer of products, etc., is generally provided. The
major purpose of dressing is to remove copper. The
separation of copper is effected by lowering the temperature
of the metal close to, but still above, the melting point of
lead. At this temperature, the solubility of copper in lead
is minimal and excess copper is rejected from the melt to
form a crust or head on the melt, and is separated by
skimming from the liquid lead. Sulfur is sometimes added to
the dressing kettle to enhance the removal of copper as
copper sulfide.
By dressing, the copper content of the lead is reduced from
as high as several tenths of a percent to as low as 0.005
percent. The liquid lead is then transferred to a second
kettle, where a second decopperizing cycle may be performed.
The dross, which may typically contain about 90 percent lead
oxide, 2 percent copper, and 2 percent antimony, with
entrained gold and silver, is treated in a byproduct
reverberatory furnace (i.e., dross reverb) to recover lead
as bullion and to produce a copper matte for subsequent
treatment by copper smelter practice.
Softening. After dressing, the bullion is subjected to a
"softening" step. This refining operation is performed to
remove antimony and produces a product of lower hardness and
strength. In contrast, lead alloyed with antimony is
commonly referred to as "hard lead" or antimonial lead.
-------
The softening may be done in either of two ways, either by
air oxidation of the molten bullion in a reverberatory
furnace or by oxidative slagging with a flux of sodium
hydroxide and sodium nitrate.
The air oxidation process consists of treatment of drossed
lead in a reverberatory type furnace with air introduced
into the bath through pipes or lances. In the air oxidation
method of softening, most of the impurities are removed in a
primary slag, which is skimmed off. The aeration is
continued with the formation of a final slag. This two-
stage slagging permits the maximum degree of removal of
impurities. The slag produced contains the oxides of
copper, arsenic, antimony, and tin as complex oxides (lead
stannate, lead arsenate, lead antimonate) and entrained
metal, and is further treated to recovery antimony, antimony
oxide, antimonial (hard) lead, a tin-rich skim (sold to tin
recovery operations), and sodium arsenate, which is
generally discarded.
After softening by the air-oxidation, reverberatory-furnace
treatment, the lead bullion is drained from beneath the slag
and treated further by fire-refining methods.
An alternative method of softening is an oxidative slagging
technique in which a sodium hydroxide-sodium nitrate mixture
is stirred into the molten lead to oxidize arsenic,
antimony, tin, etc. These impurities enter the slag as
arsenates, antimonates, and stannates of sodium. At least
two versions of the oxidative slagging process are used, the
kettle process and the Harris process. The major difference
between these two processes is that the kettle process slag
is discarded to waste, while the Harris process slag is
extensively treated by a hydrometallurgical process to
recover sodium hydroxide and, where indicated, arsenic,
antimony, and tin products.
Desilverizing and Debismuthizinq bv. Fire Refining Methods.
Electrolytic refining of softened lead is no longer
practiced in the United States. All U.S. refineries use
fire refining to effect a separation of gold and silver and,
if necessary, bismuth from the lead bullion at this point.
The processing steps involved are as follows:
(1) Desilverizing by the so-called Parke's process, in
which the softened lead is treated for several
hours with zinc metal at about 90(TF with stirring.
The zinc combines preferentially with gold and
silver to form zinc-gold and zinc- silver
24
-------
compounds. These compounds are virtually insoluble
in lead. Enough zinc is added to combine with all
the gold and silver and to saturate the lead with
zinc. The zinc-precious metal alloys accumulate on
the surface and are skimmed off. By conducting the
desilverizing in two stages, it is possible to
isolate high- gold and high-silver Dore silver-gold
alloys to facilitate the recovery of these metals
in subsequent processing. However, most plants
produce only a high silver-gold skim and separation
is made later from the combined Dore.
(2) After removal of the gold and silver, zinc is
removed by a process called vacuum dezincing, which
is conducted in a separate kettle. A portable
bell-shaped vessel with an open bottom is lowered
onto the liquid lead to form a seal and allow
evacuation of the space above the melt. The upper
portion of the dezincing chamber contains a
condenser, a stirrer extending down into the melt,
and connections to a vacuum system. As a vacuum is
applied to the chamber, any zinc in the lead leaves
the melt by vaporization and condenses on the
condenser.
Debismuthizincf. Formerly, the electrolytic method, which
utilized" a hydrofluosilicic electrolyte, was the only
feasible method for producing refined lead with an extremely
low bismuth content. With the Betterton process, bismuth
can be removed down to a content of below 0.01 percent. The
simultaneous addition of calcium and magnesium produces
CaMg2Bi2 crystals as a precipitate, which float to the
surface of the kettle and can be skimmed off. Subsequent
treatments with antimony or organic agents are sometimes
used to reduce the bismuth content further by improving the
physical separability of the fine bismuthide crystals still
remaining in the bath.
The CaMg2Bi2 crystals form a rich bismuth crust which is
transferred "to another kettle where it is melted and
subjected to a chloridizing gas treatment. The gas reacts
with the calcium and magnesium to form chlorides; these, in
turn, are treated with an oxidizing flux which forms a slag,
and also oxidizes other impurities that may be present.
After the slag containing the impurities are removed,
charcoal is added as a cover to maintain the bismuth metal
in a reduced condition while it is being cast.
25
-------
of the Debismuthized Lead. Calcium and
magnesium remaining in the lead ""after debismuthizing is
removed by stirring caustic soda (sodium hydroxide) into the
molten lead in the final refining kettle. A dry dross is
produced, which is retreated at the smelter. Any residual
zinc, antimony, or arsenic remaining in the lead at this
point is also removed. Sodium nitrate is sometimes added
along with caustic soda to effect the removal of these
impurities.
Summary. The processes employed by the six primary lead
smelters are basically the same. Various degrees of
refining are required depending upon ore constituents, as
discussed below. The one primary refinery, which is not
located on-site with a primary smelter, does not produce
process waste water pollutants, as defined in this document.
Therefore, from the standpoint of manufacturing process,
this one refinery should not be considered as part of the
primary lead subcategory; whereas, the six remaining primary
lead facilities should, for the purpose of establishing
effluent limitations, be considered as one subcategory.
Age of_Plant
A factor shared by all U.S. smelters is similarity in
processing procedures in the smelting operations. All are
conventional sinter-blast furnace smelters. As shown in
Table 4, two of the six domestic smelters were recently
constructed; whereas, the original starting dates of the
remaining four make them much older. These older plants
have all been modernized, producing a commonality of process
equipment for all six facilities. This commonality is
basically the updraft sinter machine and the hood-type blast
furnace. Age of facilities also has no effect on the
refining steps used to purify lead bullion.
Thus, age of the plant does not affect the industry
characterization.
Size
On the basis of annual production of refined lead, Plant A
is larger than the others by approximately a factor of two,
(Table H). If the single-company complex of Plants E, F,
and G is considered as a single smelter-refinery unit, the
production of the four smelter- refineries, B, C, D, and the
Plant E, F, and G Complex, can each be considered as unity
(vis-a-vis. Plant A's factor of two). Thus, there are five
important units sharing U.S. production, none of which
require a separate categorization on the basis of size. The
26
-------
production figures for concentrates and refined lead is
evidence of the fact that the Missouri smelters operate on
lead concentrates containing a larger percentage of lead.
The western smelters handle lower grade, larger variety of
concentrates to obtain a given amount of refined lead.
Raw Materials and Products
The primary ore minerals of lead are shown in Table 5.
Table 6 illustrates the ranges of compositions of lead
concentrates produced by gravity and floatation procedures.
Table 7 lists the chemical requirements of various types of
refined lead.
Smelters, Treating Concentrates, From Southeastern Missouri
Ores. There is a marked difference between the type of
concentrate handled by the western smelters and those
treated by southeastern Missouri smelters. Typical
compositions of southeastern Missouri concentrates from
mills, which have both copper and zinc removal circuits are
shown in Table 8 (figures are in percent, except for silver,
which is in ounces per ton).
The lead content of all Missouri lead concentrates is above
70 percent; zinc does not exceed 2.5-3 percent, nor copper 2
percent. There are only trace amounts of antimony, arsenic,
and bismuth. Zinc is not high enough to warrant a slag
fuming plant, so it is discarded as a constituent of the
slag. Cadmium, which builds up in the recirculating
baghouse dust, is bled off for cadmium recovery. Thus, the
major end products from the refineries associated with these
Missouri smelters are limited to refined lead and a
relatively small amount of copper as matte, and silver
bullion; for every 90,700 kkg (100,000 tons) of lead
produced, there is an associated 1810 - 2270 kkg (2000 -
2500 tons) of copper matte (containing about 45 percent Cu,
10 to 20 percent Pb) produced, along with approximately
2,840 to 3,410 kg of silver. Because of the lower impurity
content, especially bismuth, fewer refining steps are
required for Missouri refined lead production.
Western Smelters Treating_Domestic and_ImBorted_Ores All the
U.S. smelters outside the Missouri group (Plants D, E, and
F) are custom smelters, handling both domestic and imported
ores. There is, of course, no such thing as a typical
2'7
-------
TABLE 5. ORE MINERALS OF LEAD
Mineral
Chemical Composition
Remarks
Galena
Cerussite
PbS
PbCO,
Anglesite
PbSO,
Principal ore mineral,
commonly associated with
cerussite and anglesite
Results of weathering of
galena; frequently occur-
ring within a galena
deposit
Ditto
28
-------
TABLC 6. RANGES OF COMPOSITION;. OF LEAD CONCENTRATES PRODUCLD
BY GRAVITY 7\ND FLOATATION rROCEDUREE
Constituent
Pb
Zn
Au(a)
Ag(a)
Cu
As
Sb
Fe
Insolubles
CaO
S
Bi
Cd
Percent
Lead Concentrates
45-80
0-5.0
0-17
0-3800
0-3
0.01-4.0
0.01-2.0
1.0-8.0
0.5-4.0
Trace -3.0
10-30
Trace -0.1
Trace -0.2
(a) Grams/metric ton.
29
-------
TABLE 7. CHEMICAL REQUIREMENTS
Composition, percent
Silver, max
Silver, min
Copper, max
Copper, min
Silver and copper together,
Corroding
Lead
0.0015
—
0.0015
--
Chemical
Lead
0.020
0.002
0.080
0.040
Acid-
Copper
Lead
0.002
--
0.080
0.040
Common
Desilverized
Lead
0.002
—
0.0025
--
max
Arsenic, antimony, and tin
together, max
Zinc, max
Iron, max
Bismuth, max
Lead (by difference), min
0.0025
0.002
0.001
0.002
0.050
99.94
0.002
0.001
0.002
0.005
99.90
0.002
0.001
0.002
0.025
99.90
0.005
0.002
0.002
0.150
99.85
30
-------
TABLE 8. TYPICAL SOUTHEASTERN MISSOURI LEAD CONCENTRATE ANALYSES
Pb
Cu
Zn
Fe
Ni
Co
As
Insol CaO MqO
1.42 74.8 0.64 1.05 2.08 0.10 0.06 15.1 0.009 1.1 1.34 0.90
1.4 76.1 0.85 1.29 1.04 0.2 0.08 15.4 0.006 1.3 0.94 0.75
-------
analysis of the concentrates handled by these plants.
However/ an understanding of the complexity and variety of
the concentrates treated by these smelters can be had by
examining the operation at one of them. Plant E. Last year
this smelter treated 107,000 kkg (118,000 tons) of lead
concentrate with a reported average analysis of 0.50 oz/ton
Au, 168.8 oz/ton Ag, 38 percent Pb, and 5.4 percent Cu.
From these concentrates (with additions of siliceous lead
ore, residues from the zinc fuming plant, etc.), the
intermediate products shown in Table 9 were produced.
Lead bullion from this plant is sent to a refinery, which
also treats bullion from Plant F. Last year a combined
bullion from both plants amounted to 119,720 kkg (132,000
tons). This with 3630 kkg (4,000 tons) of secondary lead
and dross was treated to produce gold and silver Dore and
the following base metal products:
Refined Lead 103,400 kkg (114,000 tons)
Antimonial Lead Alloys 12,150 kkg (13,400 tons)
Other Lead Alloys 6,666 kkg (7,350 tons)
Refined Bismuth (99.99
Percent) 544 kkg (600 tons)
Copper Matte 254 kkg (280 tons)
Telluride Slag 109 kkg (120 tons)
The concentrate handled at Plant D had a higher average lead
content than Plant E concentrates (a reported 62 percent Pb
with 6.6 percent S). Last year, the refinery at Plant D
produced the following product mix:
Refined Lead 120,630 kkg (133,000 tons)
Gold 239 kg (8,400 oz)
Silver 305,584 kg (10,760,000 oz)
Antimony 580 kkg (639 tons)
Generally, a large number of products are made at the
western smelters, but this additional production does not
produce additional process waste water. One byproduct,
metallurgically produced sulfuric acid, does produce process
waste water at lead smelters. This subject is discussed
below.
Location
Of the seven primary lead plants in the United States, one
(Plant F) has no discharge by virtue of climatic conditions,
one other (Plant G) discharges noncontact cooling water, but
32
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TABLE 9. INTERMEDIATE PRODUCTS OF A WESTERN SMELTER
Gold, Silver, Lead, Copper, Cadmium, Zinc,
oz/ton oz/ton % % % % (Tons) kkg
Lead
Bullion 1.7 3.48 97.5 (64,000) 58,048
Soda Ash
Matte 0.1 88 6.4 43.5 (6,700) 6,077
Soda Ash
Speiss 6.8 440 6.8 64 (11,000) 9,980
Lead Baghouse
Dust 0.5 6.7 17.5 17.6 (1,200) 1,090
Zinc Fume 2.7 7.7 0.17 70 (36,000) 32,650
-------
has no discharge of process waste waters by virtue of
process variation (i.e., refining operations only), and the
balance of the plants all have some discharge of process
waste water pollutants to navigable waters. The data on net
annual accumulation of water and mean temperature given in
Table 10 indicate that not all existing plants in the
industry have the available option of achieving no discharge
by means of total impoundment and solar evaporation.
Air Pollution Control
Particulate^Matter. Large amounts of dust and fume are
generated during sintering and reduction in the blast
furnace. The conventional dust collection device used at
primary lead smelters is the baghouse. One baghouse is used
on the sinter machine offgas, while a second baghouse is
employed on the blast furnace effluent. There is only one
known application of an electrostatic precipitator to a
sinter machine offgas at one domestic smelter. These dust
collection techniques operate dry, except when water is
injected into the gas stream for gas cooling prior to the
baghouse. This water is evaporated. Other particulate
control points (i.e., transfer points, hygiene areas, etc.)
are usually either controlled by the main baghouses,
separate, smaller baghouses, or smaller closed-loop wet
collection devices. The dusts collected are usually mixed
with water in a pugmill and then returned to the process as
recycle material.
Sulfur Oxide Control. The majority of the sulfur contained
in the feed is converted to sulfur dioxide in the front
portion of the sinter machine. This gas stream is
segregated from the weaker (lower SO2 concentration)
offgases from the rear section of the sinter machine at
three of the six domestic smelters. The strong SO2 effluent
is sent to a metallurgical sulfuric acid plant at these
three smelters. The other three plants collect all of the
sinter machine offgases in one flue and pass them to the
baghouse with no sulfur oxide control. Since the potential
of sulfur oxide control at these three smelters exists and
may result in the operation of an acid plant at a future
date, a separate category based upon air pollution control
is not warranted.
Industry Categorization Summary
Since one of the six currently operating primary lead
smelters operates at no discharge of process waste water
34
-------
TABLE 10 CLIMATIC CHARACTERISTICS AT U.S. LEAD SMELTER LOCATIONS
OJ
Plant
A
B
C
D
E
F
G
Mean Max
Temp,
January,
C (F)
7
8
8
-1
-3
13
0.
(44)
(46)
(46)
(30)
(26)
(56)
6(33)
Mean Min
Temp,
January,
C (F)
-4
-3
-2
-8
-13
•» 1
-11
(24)
(27)
(28)
(18)
(8)
(30)
(12)
Mean Max
Temp,
July,
C (F)
33
32
32
29
30
34
32
(91)
(90)
(90)
(84)
(86)
(94)
(90)
Mean Min
Temp,
July,
C (F)
19
18
17
9
11
20
19
(66)
(64)
(62)
(48)
(52)
(68)
(66)
Mean Annual
Precipitation,
Cm (in)
97
107
107
79
25
20
66
(38)
(42)
(42)
(31)
(10)
(8)
(26)
Mean Annual
Lake
Evaporation,
Cm ( in)
91
97
97
76
66
183
102
(36)
(38)
(38)
(30)
(26)
(72)
(40)
Annual
Accumulation,
Cm ( in)
+6
+10
+10
+3
-41
-163
-36
(+2)
(+4)
(+4)
(+1)
(-16)
(-64)
(-14)
-------
pollutants by virtue of location, the primary lead
subcategory should be segmented for the purposes of
establishing effluent limitations into two geographical
groups, smelters geographically located in areas of net
evaporation and smelters geographically located in areas of
net precipitation. The one primary lead refinery, not
physically located on-site with a primary lead smelter,
should not be considered as part of the primary lead
subcategory, since, due to processes employed at this one
site, process waste waters are not produced.
36
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SECTION V
WASTE CHARACTERIZATION
Introduction
The sources of waste water within the primary lead industry
are set forth in this section. The kinds and amounts of
waste water characteristics are discussed in terms of
volumes of flow and are related to process operations and
current control and treatment practices.
Sources of Waste Water
The process operations found in primary lead plants are
discussed in the previous section. The sources of waste
water are indicated in the generalized diagram given in
Figure 5, and are discussed in the following paragraphs.
Various applications of noncontact cooling are found in
primary lead smelters. These applications include the
cooling of various parts of sinter machines and the jackets
or outer shells of the blast furnace, cooling of door frames
or other portions of reverberatory furnaces (if present),
bearing cooling, and, if one is present at the plant, the
cooling of sulfuric acid plant reactors and other
components. Other noncontact cooling water applications may
be related to power and steam plants if they are present at
the lead smelter. In the primary lead industry, metal
casting cooling water is characteristically a noncontact
cooling water source. The waste water streams from such
noncontact cooling operations are not within the scope of
this document and are only discussed here to differentiate
them from process waste waters. Process waste water streams
identified within lead smelter operations include:
• Streams from the gas cleaning train associated with
acid plant operations, including water from such
sources as gas conditioning (humidification)
chambers, electrostatic precipitator sumps, or
bleed streams from weak acid wet scrubbers;
• Streams from blast furnace slag, speiss, and/or
dross granulation operations, usually a bleed or
intermittent overflow stream from a recirculating
water system;
37
-------
CO
00
Cooling Tower
or Reservoir
Sinter
Plant
Blast
Furnace
Noncontact
Cooling
Water
I
I SO,, -:
Gas Cleaning
Train
Acid
Plant
Blowdown
Acid
Plant
Blast
Furnace
Slag
Granulation
Recycle
Pond
Ventilation
Scrubbers
Settling
Figure 5. Generalized diagram of water uses and v/aste water sources in prirrary lead plants.
-------
• Similarly, water circuits for cooling of hot gases
from either the blast furnace or the sintering
operation, or for air pollution control in wet
scrubbers. These were found to be operating in
closed loop fashion (i.e., without an effluent)
except in the case of one plant.
The process waste water streams identified as components of
discharge waters include acid plant blowdown (in three
plants), slag granulation waste water (in five plants), and
wet scrubber waste water (in four plants). Data developed
on the identifiable constituents of plant discharges and
calculated unit waste loads for one smelter (given in Tables
11 and 12) represent discharges from the plant as reported
in 1971. The discharge at that time totaled about 8,175,600
I/day (1500 gpm) and contained suspended and dissolved
solids (mostly sulfates), as well as identifiable amounts of
cadmium, lead, and zinc. The data in Table 13 represent the
discharge anticipated after the revision of the water
circuits at the plant. In order to achieve the projected
waste loads, the total flow of effluent will be reduced from
8,175,600 I/day (1500 gal/min) to 1,635,120 I/day (300
gal/min), with lime treatment of the acid plant blowdown, to
achieve the projected waste loads listed in Table 13. The
calculated specific discharge rate would be reduced from
about 14,000 1/kkg (3400 gal/ton) to 2,900 1/kkg (690
gal/ton). This latter figure would include 408,780 I/day
(75 gpm) of treated acid plant blowdown, equivalent to a
calculated minimum rate of blowdown of 1500 I/day (360
gal/ton) of acid produced or 713 1/kkg (170 gal/ton) of lead
produced. Similarly, waste characteristics for other lead
smelters are given in Tables 14 through 17, which indicate
the waste characteristics before and after revision of the
water systems.
For example, waste characteristics for one lead smelter in
1971 are shown in Table 14. According to present plans,
this discharge will be greatly reduced before 1975. The
reduction in effluent will be achieved by various measures,
some presently completed, including closed-loop cooling
water circuits for the acid plant, with a cooling tower
installed in the metal casting cooling circuit and acid
plant blowdown being appropriately treated and then used for
dross and slag granulation. Ventilation air venturi
scrubbers will operate in closed circuits and will provide
additional evaporative capacity.
The waste characteristics given in Table 15 are for the
discharge from settling ponds which receive waste water from
a slag granulating operation. This is the only discharge
39
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TABLL 11. WASTE EFFLUENTS FROM PLANT A (OUTFALL No. 001)
Contributing Operations: Slag granulation , blast-furnace
cooling water, miscellaneous blowdowns
Parameter
pH
Alkalinity
COD
Total Solids
Dissolved Solids
Suspended Solids
Oil and Grease
Sulfate (as S)
Chloride
Cyanide
A lumi rum
Arsenic
Cadmium
Calcium
Chromium
Copper
Iron
Lead
Magnesium
Mercury
Molybdenum
Nickel
Po t a s s i uin
Selenium
Silver
Sodium
To llur ium
Zi nc
Flow,
I/day
(gal /day)
Production,
kkg/d^y
(l ons/day)
Total
Plant
Intake ,
mg/1
7.6
203
8
--
408
3
—
145
18
__
—
—
—
70
—
0.02
1.70
0.12
.31
--
—
0.03
—
—
—
—
--
0.12
(2,592,000)
571.4
(630)
Total
Plant
Discharge ,
mg/1
8.3
186
8
—
500
36
--
215
—
—
—
--
—
—
—
0.02
—
0.30
--
—
--
0.04
—
--
—
—
—
0.50
5,995,440
(1,584,000)
571.4
(630)
Net
Change,
mg/1
-17
0
—
92
33
-_
70
—
—
--
--
--
—
—
0
--
0.18
--
--
--
0.02
--
--
—
—
—
0.38
Net Loading_
kg /day kg/kkg
NLC(a)
0
--
551.54 0.97
197.84 0.35
_-
419.65 0.73
—
—
-_
--
__
-_
—
0 0
__
1.08 0.002
--
—
__
0.12 0.0002
--
-_
--
—
—
2.28 0.004
Ib/ton
--
0
-.
1.94
0.70
-_
1.46
--
--
_-
__
__
__
-_
0
__
0.004
—
--
--
0.0004
__
__
--
—
--
0.008
Source: This contract and 1971 RAPP data.
(a) NLC = no load calculable.
40
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TABLE 12. WASTE EFFLUENTS FROM PLANT A (OUTFALL No.: 002)
Contributing Operations: Casting, cooling, acid-plant blowdown,
dross granulation, noncontact cooling water
Parameter
PH
Alkalinity
COD
Total Solids
Dissolved Solids
Suspended Solids
Oil and Grease
Sulfate (as S)
Chloride
Cyanide
Altimirum
Arsenic
Cadmium
Calcium
Chromium
Copper
Iron
Lead
Magnesium
Mercury
Molybdenum
Nickel
Potassium
Selenium
Silver
Sodium
Tellurium
Zinc
Flow,
I/day
(gal /day)
Production,
kkg/day
(tons/day)
Total
Plant
Intake,
mg/1
7.6
203
8
—
408
3
--
145
18
--
--
—
--
70
--
0.02
1.70
0.12
0.31
--
—
0.03
—
—
—
—
—
0.12
(2,592,000)
571.4
(630)
Total
Plant
Discharge ,
mg/1
6.8
260
200
—
980
500
--
500
—
—
--
—
1.9
40
—
0.10
1.0
0.50
—
—
—
--
—
—
—
200
--
10
2,180,160
(576,000)
571.4
(630)
Net
Change,
mg/1
__
'57
192
—
572
497
--
355
—
—
—
--
1.9
-30
—
0.08
-9.7
0.38
--
—
—
—
—
—
—
—
—
9.88
Net Loading
kg/day
__
124.26
418.56
—
1246.96
1083.46
--
773.90
—
--
—
—
4.13
NLC
—
0.17
NLC
0.83
—
—
—
—
—
—
_-
—
—
21.54
kg/kkg
..
0.22
0.73
--
2.18
1.90
_-
1.35
—
--
—
—
0.007
--
—
0.0003
—
0.001
—
--
--
--
--
—
__
—
--
0.038
Ib/ton
..
0.44
1.46
__
4.36
3.80
__
2.70
-_
--
—
--
0.014
--
—
0.0006
—
0.002
--
-_
__
_-
__
—
__
-_
__
0.076
Source: 1971 RAPP Data.
41
-------
TABLE 13- WASTE EFFLUENTS FROM PLANT A
(EFFLUENT FROM PROJECTED TREATMENT PLANT WITH
REVISED WATER CIRCUITS)
Parametc •
pH
Alkalini i
COD
Total So '•
Dissolve h- il ids
Suspend '-'i>lids
Oil and i -,se
Sulfatt S)
Chloric-
Cyanide
A lumii i,
Arsenic
Cadmium
Calci uni
Chromiuii
Copper
Iron
Lead
Magnesium
Mercury
Molybdenum
Nickel
Potassium
S e 1 e n i um
S ilver
Sodium
Tellurium
Zinc
Flow,
I/day 9
(gal/day) (2
Production ,
kkg/day
(tons/day )
Total
Plant
Intake ,
mg/1
7.6
203
8
__
408
3
--
145
18
--
--
—
—
70
--
0.02
1.70
0.12
31
--
--
0.03
--
--
__
.-
--
0.16
,810,720
,592,000)
571.4
(630)
Total
Plant Net
Discharge, Change. Net Loading
niR/1 mg/1 kg/day kg/kkg Ib /ton
8.0
--
--
— «- — —
550 142 232.17 0.41 0.82
30 27 44.15 0.08 0.16
--
215 50 81.75 0.14 0.28
--
—
--
--
--
--
—
0.02 000 0
0.6 -1.1 NLC
0.30 0.18 0.29 0.0005 0.001
--
—
--
0.08 0.05 0.08 0.0001 0.0002
--
__
__
-— — — — - __ __
-- — — __ __ __
°'50 0.34 0.56 0.001 0.002
1,635,120
(432,000)
571.4
(630)
Source: This contract, 1973.
42
-------
TABLE 14. WASTE EFFLUENTS FROM PLANT B (OUTFALL No.: 001)
Contributing Operations: Noncontact cooling, treated acid-
plant blowdown
Parameter
P«
Alkalinity
COD
Total Solids
Dissolved Solids
Suspended Solids
Oil and Grease
Sulfate (as S)
Chloride
Cyanide
Aluminum
Arsenic
Cadmium
Ca ] cium
Chromium
Copper
] von
], .-id
t-'!.i",nes ium
;•' T.ury
Mo I vbdcnum
Nickel
Potassium
Se len i IUTI
Silver
Sod iuin
Te llur j urn
Zinc
Flow,
1/da^
(gal/L,,^ )
Product 01, ,
kkg/n
(tons/, )
Total
Plant
Intake,
mg/1
7.1
110
8
._
4,481
2
6.0
338
45
--
—
--
--
112
--
0.20
—
—
56
--
--
0.12
--
—
--
34.5
--
0.44
2,725,200
(720,000)
331
(365)
Total
Plant
Discharge ,
mg/1
6.5
8
21
__
1,565
15
0.4
975
49.7
—
—
0.01
1.2
290
—
0.020
0.4
0.52
63
0.0005
--
0.250
--
—
—
67
--
5.5
408,780
(108,000)
331
(365)
Net
Change,
mg/1
..
-102
13
_-
-2,916
13
-5.6
637
4.7
—
--
--
1.2
178
—
-0.18
NLC
0.52
7
'--
--
0.13
--
—
--
32.5
--
5.06
Net Loading
kg/day
NLC
5.31
__
NLC
5.31
NLC
260.39
1.92
—
__
-_
0.49
72.76
--
NLC
NLC
0.21
2.86
—
--
0.05
—
—
—
13.29
—
2.07
kg/kkg
--
0.016
__
—
0.016
—
0.79
0.006
—
__
__
0.001
0.22
--
--
--
0.0006
0.009
--
--
0.0002
—
—
—
0.04
—
0.006
Ib/ton
_-
0.032
__
—
0.032
__
1.58
0.012
--
__
__
0.002
0.44
__
__
--
0.0012
0.018
--
--
0.0004
—
—
—
0.08
—
0.012
Source: RAPP Data.
43
-------
TABLE 15' WASTE EFFLUENTS FROM PLANT c (OUTFALL FROM SETTLING
POND)
Contributing Operations: Slag granulation
Parameter
pH
Alkalinity
COD
Total Solids
Dissolved Solid ,
Suspended Solid--
Oil and Grease
Sulfate (as S)
Chloride
Cyanide
Alumirum
Arsenic
Cadmium
Calcium
Chromium
Copper
Iron
Lead
Magnesium
Mercury
Molybdenum
Nickel
Potassium
Selenium
Silver
Sodium
Tellurium
Zinc
Flow,
I/day
(gal/day)
Production ,
kkg/day
(tons/day)
Total Total
Plant Plant
Intake, Discharge,
mg/1 ms/1
8.0
0
<4
198
18
_ —
2
14
Nil
_ —
__
44
0.055
__
Nil
21
--
<0.05
__
__
__
1.2
—
0.03
1,506,430 1,477
(398,900) (390
268.5
(296)
7.6
8
4.4
301
15
112
14
Nil
< 0.02
0.08
48
<0.01
0.009
__
0.85
23
0.0024
0.05
__
_ —
_..
12
_„
1.2
,058
,240)
268.5
(296)
Net
Change,
mg/1
8
0.4
103
-3
110
0
0
0.08
4
-0.046
0.85
2
_M
10.8
*. •.
1.17
Net Loading_
kg/day
11.82
0.59
152.14
NLC
162.48
o
o
00.12
5.91
NLC
1.26
2.95
15.95
1.73
kg/kkg
0.04
0.002
0.57
0.61
n
0.0004
0.02
0.005
0.01
0.06
0.006
Ib/ton
0.08
0.004
1.14
1.22
""
0.0008
0.04
0.01
0.02
0 12
0.012
Source: Producer's data.
44
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TABLE 16. PRESENT CONTROL AND TREATMENT METHODS FOR
PROCESS hASTE WATER IN PRIMARY LEAD INDUSTRY
Acid Plant Blowdown Slag Granulation Scrubbing Current^ Process
Plant Recycle Lime Effluent Recycle
Designation Treatment cu m/day(gpm)
A Yes Yes 409 'a' Yes
(75)
B Yes Yes 251(a'b) Yes
(46)
C (c) (c) (c) Yes
D Yes Yes 272 Yes
(75)
No 0(a> (c)
(d)
No 3815 No
(700)
No 0 Yes
Treatment Effluent Discharge cu m/day (gpm)
No 0 1640
(300)
No 0 330
(50)
(c) (c) 0
Yes 1090(a Ole)
(200)
0
No 0
(a) Reused as process water for some other integrated function.
(b) Discharged, either directly or commingled, to navigable water.
(c) Not applicable.
(dj Consumed in slag pile.
(e) Except for smalljhighly intermittent flow produced during periodic clean-out of settling pond.
-------
TABLL 17. CONCENTRATIONS OF SELECTED CONSTITUENTS OF ACID PLANT
BLCWDCMI AFTER LIMING FROM FRT1ARY NOKFERROOS SMELTERS
Pollutant
Parameter
pH
Cadmium
Lead
Mercury
Zinc
Concentrations, mg/1
Copper
Smelter
7.1
0.06
0.19
0.0001
18.9
Zinc (a)
Smelter
8.2
0.02
0.15
0.004
50
Smelter
9.5
0.7
2.7
0.0009
1.2
(a) Data obtained under EPA Contract No. 68-01-1518.
(b) Limed and-settled acid plant blowdown at Plant B.
46
-------
from the subject lead smelter. All other uses of water in
the smelter (which does not include an acid plant) are for
indirect cooling, with a bleed stream being totally
evaporated by use for cooling of gases from the blast
furnace and sintering plant. Current plans at this smelter
include reuse of granulation water for sinter plant offgas
cooling.
In the case of another lead smelting operation for which
data were obtained, the only discharge was blowdown from a
cooling tower serving indirect cooling water circuits. The
process water streams at this smelter, consisting of slag
granulation and gas conditioning circuits, operate in a
closed loop fashion with no bleed streams. No acid plant
was included in the operations at this smelter.
Summary
The development of data on process waste water
characteristics in the primary lead smelting industry has
established that, for those existing primary smelters
currently discharging process waste water, three (soon to be
two) discharges contain waste water from slag granulation
operations and two (of the three with acid plants) contain
components from lime treated acid plant blowdown.
In those effluents containing the above process waste water
components, the characteristic constituents identifiable in
the effluent include dissolved solids (principally
sulfates), cadmium, lead, mercury, and zinc. Waste
characteristics are strongly influenced by the current
practices of lime treatment of acid plant blowdown and
settling of slag granulation water, and, in some cases, the
total control through recycle and reuse of such streams.
47
-------
SECTION VI
SELECTION OF POLLUTANT PARAMETERS
Introduction
The previous section provided quantitative data on a number
of parameters that characterized the process waste water
discharges from domestic primary lead smelters and
refineries. On the basis of rationales presented in this
section for selecting and excluding individual constituents,
the following pollutant parameters were identified to occur
in sufficient quantities to warrant their control and
treatment:
PH
Total suspended solids
Cadmium
Mercury
Lead
Zinc
A broad range of possible pollutants were considered as
potential constituent additions to the waste waters from U.
S. smelters and refineries. The results of this survey are
summarized in the previous section where the compositions of
each of these constituents in both the source and discharge
water for each smelter are given. Aside from the obvious
reason that the constituent in question was not present in
important enough amounts to be considered a significant
parameter, the following reasoning was used to determine
whether or not to exclude a given item from consideration as
a pollutant requiring an effluent limitation.
(1) There are insufficient data on which to base an
effluent limitation.
(2) The availability and cost of the required control
or treatment technology is beyond the scope of
"best practicable" or "best available" as defined
by the Federal Water Pollution Control Act
Amendments of 1972.
(3) The pollutant in question will be removed
simultaneously with another pollutant by co-
precipitation, clarification, etc.
49
-------
In light of this reasoning, the following discussion
presents rationales used to establish which are significant
parameters, and which are not. The waste water parameters
of pollutional significance are considered first.
Rationale for the Selection
of Pollutant Parameters
The control and treatment technologies discussed in Section
VII describe the current practices, as well as those which
are under construction, by the industry which are used to
treat and control the selected pollutants. From these
discussions, it was concluded that the discharge of total
suspended solids and heavy (trace) metals can be controlled
by pH adjustment and suspended solids removal.
Setting effluent limitations on cadmium and zinc, which are
the principal pollutant metals in the process waste waters
from the primary lead industry, and specifying a pH range
will in turn limit the other trace metals found in these
waste waters. Such metals include aluminum, antimony,
cobalt, chromium, iron, magnesium, manganese, nickel,
selenium, silver and tin.
There is an optimum pH for precipitation of each metal,
which results in its greatest reduction by solids removal
(settling or filtration). The pH selected for the mixture
of metals associated with the primary lead industry is a
compromise between the maximum removal of cadmium and zinc,
as hydroxides, and that suited for the maximum removal of
other metals associated with the process waste waters.
Coprecipitation of these heavy metal hydroxides with cadmium
and zinc hydroxide (and also aluminum, iron and magnesium
hydroxide, if they are present in the waste waters) at a pH
at which optimum Coprecipitation occurs is used in good
water treatment practice. Therefore, an appropriate pH
adjustment followed by solids removal will reduce all the
metals to levels consistent with the best control technology
currently available.
pH, Acidity and Alkalinity
Acidity and alkalinity are reciprocal terms. Acidity is
produced by substances that yield hydrogen ions upon
hydrolysis and alkalinity is produced by substances that
yield hydroxyl ions. The terms "total acidity" and "total
alkalinity" are often used to express the buffering capacity
of a solution. Acidity in natural waters is caused by
carbon dioxide mineral acids, weakly dissociated acids, and
50
-------
the salts of strong acids and weak bases. Alkalinity is
caused by strong bases and the salts of strong alkalies and
weak acids.
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 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 cf pH or rapid pH changes can exert stress
conditions or kill aquatic life outright. Dead fish,
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 aquatic life of many
materials is increased by changes in the water pH.
Metalocyanide 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. Ammonia is more lethal with a higher pH.
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.
When in the range of pH 7 to 10, the acid wastes have been
neutralized, but are not excessively alkaline. Overall
concentrations of dissolved metals can be expected to be at
a minimum when pH of the discharge is maintained in this
range.
Total_Suspended_Sglids
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,
51
-------
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.
Deposits containing organic materials may deplete bottom
oxygen supplies and produce hydrogen sulfide, carbon
dioxide, methane, and other noxious gases.
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 on 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. When of an organic and therefore decomposable
nature, solids use a portion or all of the dissolved oxygen
available in the area. Organic materials also serve as a
seemingly inexhaustible food source for sludgeworms and
associated organisms.
Turbidity is principally a measure of the light absorbing
properties of suspended solids. It is frequently used as a
52
-------
substitute method of quickly estimating the total suspended
solids when the concentration is relatively low.
Total suspended solids is a gross measure of the solids
remaining in suspension following treatment of precipitated
dissolved metals. Compliance with a TSS limitation insures
that effective phase separation has been achieved.
Relatively unsophisticated methods, the simplest of which is
provision for adequate settling time in a settling pond, are
available for the treatment of waste water to decrease the
suspended solids content.
Cadmium
Cadmium in drinking water supplies is extremely hazardous to
humans, and conventional treatment, as practiced in the
United States, does not remove it. Cadmium is cumulative in
the liver, kidney, pancreas, and thyroid of humans and other
animals. A severe bone and kidney syndrome in Japan has
been associated with the ingestion of as little as 600
ug/day of cadmium.
Cadmium is an extremely dangerous cumulative toxicant,
causing insidious progressive chronic poisoning in mammals,
fish, and probably other animals because the metal is not
excreted. Cadmium could form organic compounds which might
lead to mutagenic or teratogenic effects. Cadmium is known
to have marked acute and chronic effects on aquatic
organisms also.
Cadmium acts synergistically with other metals. Copper and
zinc substantially increase its toxicity. Cadmium is
concentrated by marine organisms, particularly molluscs,
which accumulate cadmium in calcareous tissues and in the
viscera. A concentration factor of 1000 for cadmium in fish
muscle has been reported, as have concentration factors of
3000 in marine plants, and up to 29,600 in certain marine
animals. The eggs and larvae of fish are apparently more
sensitive than adult fish to poisoning by cadmium, and
crustaceans appear to be more sensitive than fish eggs and
larvae.
Cadmium is associated with lead concentrates and is often
recovered from recirculating baghouse catches at primary
lead smelters.
Although elemental mercury occurs as a free metal in some
parts of the world, it is rather inert chemically and
53
-------
insoluble in water; hence, it is not likely to occur as a
water pollutant. It is used in scientific and electrical
instruments, in dentistry, in power generation, in solders,
and in the manufacture of lamps. Mercuric salts occur in
nature chiefly as the sulfide HgS, known as cinnabar, but
numerous synthetic organic and inorganic salts of mercury
are used commercially and industrially. Many of the
mercuric and mercurous salts are highly soluble in water.
Mercury and mercuric salts are considered to be highly toxic
to humans. They are readily absorbed by way of the
gastrointestinal tract, and fatal doses for man vary from 3
to 30 grams. Adults may safely drink water containing about
4 to 12 mg of Hg per day and a fatal dose of such water
would be about 75 to 300 mg per day.
Mercuric ions are considered to be highly toxic to aquatic
life. For freshwater fish, concentrations of 0.004 to 0.02
mg/1 of Hg have been reported harmful. Mercury salts, such
as the unstable compounds mercuric sulfate and nitrate, have
killed minnows at a concentration of 0.01 mg/1 as mercury,
after 80-92 days. At concentrations of 0.05 and 0.1 mg/1 as
mercury, fish were killed in 6 to 12 days. For
phytoplankton, the minimum lethal concentration of mercury
salts has been reported to range from 0.9 to 60 mg/1 of Hg.
The toxic effects of mercuric salts are accentuated by the
presence of trace amounts cf copper.
Mercury was included as a pollutant parameter because it
appeared in the waste water of a complex operation
consisting of both a lead smelter and a zinc electrolytic
plant. Mercury is associated with some lead concentrates,
such as those of the Coeur d'Alene area and some imported
ones.
Lead
Some natural waters contain lead in solution, as much as
0.4-0.8 mg/1, where mountain limestone and galena are found.
In the U.S.A., lead concentrations in surface and ground
waters used for domestic supplies range from traces to 0.04
mg/1 averaging about 0.01 mg/1. Lead may also be introduced
into water as a constituent of various industrial and mining
effluents, or as a result of the action of the water on lead
in pipes.
Foreign to the human body, lead is a cumulative poison. It
tends to be deposited in bone as a cumulative poison. The
intake that can be regarded as safe for everyone cannot be
stated definitely, because the sensitivity of individuals to
54
-------
lead differs considerably. Typical symptoms of advanced
lead poisoning are constipation, loss of appetite, anemia,
abdominal pain, and tenderness, pain, and gradual paralysis
in the muscles, especially of the arms. A milder and often
undiagnosed form of lead poisoning also occurs in which the
only symptoms may be lethargy, moroseness, constipation,
flatulence, and occasional abdominal pains. Lead poisoning
usually results from the cumulative toxic effects of lead
after continuous consumption over a long period of time,
rather than from occasional small doses. Immunity to lead
cannot be acquired, but sensitivity to lead seems to
increase. Lead is not among the metals considered essential
to the nutrition of aninr.als or human beings. Lead may enter
the body through food, air, and tobacco smoke as well as
from water and other beverages. The exact level at which
the intake of lead by the human body will exceed the amount
excreted has not been established, but it probably lies
between 0.3 and 1.0 mg per day. The mean daily intake of
lead by adults in North America is about 0.33 mg. Of this
quantity, 0.01 to 0.03 mg per day are derived from water
used for cooking and drinking. A total intake of lead
appreciably in excess of 0.6 mg per day may result in the
accumulation of a dangerous quantity of lead during a
lifetime. Lead in an amount of 0.1 mg ingested daily over a
period of years has been reported to cause lead poisoning.
The daily ingesticn of 0.2 mg lead is considered excessive
by one authority. Lead poisoning among human beings is
reported to have been caused by the drinking of water
containing lead in ccncentrations varying from 0.042 mg/1 to
1.0 mg/1 or more. There is a feeling that 0.1 mg/1 may
cause chronic poisoning if the water is used continuously,
expecially among hypersensitive persons. For many years,
the mandatory limit for lead in the USPHS Drinking Water
Standards was 0.1 mg/1; but in the 1962 Standards, the limit
for lead was lowered to 0.05 mg/1. In the WHO International
Standard and WHO European Standards, the limit for lead has
been set a 0.1 mg/1. Uruguay has used a standard as low as
0.02 mg/1. Several countries use 0.1 mg/1 as a standard.
Traces of lead in metal-plating baths will affect the
smoothness and brightness of deposits. Inorganic lead salts
in irrigation water may be toxic to plants. In the culture
of oats and potatoes, lead nitrate in concentrations of 1.5
to 25 mg/1 had a stimulating effect, but at concentrations
over 50 irg/1 all plants died in a week's time. Lead at a
concentration of 51.8 rrg/1 of nutrient solution was slightly
injurious to sugar beets grown in sand culture. Germination
of cress and mustard seeds in solution culture was
completely inhibited by a 2760 mg/1 lead solution, during an
55
-------
exposure period of 18 days. Germination was delayed and
growth was retarded by 345-1380 mg/1 of lead.
Farm animals are poisoned by lead from various sources,
including paint, more frequently than by other metallic
poisons. It is not unusual for cattle to be poisoned by
lead in the water; the lead need not necessarily be in
solution, but may be in suspension. Chronic lead poisoning
among animals has been caused by 0.18 mg/1 of lead in soft
water. Chronic changes in the central nervous system of
white rats were observed after an ingestion of 0.005 mg of
lead per kg of body weight. Most authorities agree that 0.5
mg/1 of lead is the maximum safe limit for lead in a potable
supply for animals.
The toxic concentration of lead for aerobic bacteria is
reported to be 1.0 mg/1; for flagellates and infusoria, 0.5
mg/1. The bacterial decomposition of organic matter is
inhibited by 0.1 to 0.5 mg/1 of lead. In water containing
lead salts, a film of coagulated mucus forms, first over the
gills, and then over the whole bcdy of the fish, probably as
a result of a reaction between lead and an organic
constituent of mucus. The death of the fish is caused by
suffocation due to this obstructive layer. In soft water,
lead may be very toxic; in hard water equivalent
concentrations of lead are less toxic.
Zinc
Occurring abundantly in rocks and ores, zinc is readily
refined into a stable pure metal and is used extensively for
galvanizing, in alloys, for electrical purposes, in printing
plates, for dye-manufacture and for dyeing processes, and
for many other industrial purposes. Zinc salts are used in
paint pigments, cosmetics, Pharmaceuticals, dyes,
insecticides, and other products too numerous to list
herein. Many of these salts (e.g., zinc chloride and zinc
sulfate) are highly scluble in water; hence it is to be
expected that zinc might occur in many industrial wastes.
On the other hand, some zinc salts (zinc carbonate, zinc
oxide, zinc sulfide) are insoluble in water and consequently
it is to be expected that some zinc will precipitate and be
removed readily in most natural waters.
In zinc mining areas, zinc has been found in waters in
concentrations as high as 50 mg/1. In most surface and
ground waters, it is present only in trace amounts. There
is some evidence that zinc ions are adsorbed strongly and
permanently on silt, resulting in inactivation of the zinc.
56
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Concentrations of zinc in excess of 5 mg/1 in raw water used
tor drinking water supplies cause an undesirable taste which
persists through conventional treatment. Zinc can have an
adverse effect on man and animals at high concentrations.
In soft water, concentrations of zinc ranging from 0.1 to
1.0 mg/1 have been reported to be lethal to fish. zinc is
thought to exert its toxic action by forming insoluble
compounds with the mucous that covers the gills, by damage
to the gill epithelium, or possibly by acting as an internal
poison. The sensitivity of fish to zinc varies with
species, age and condition, as well as with the physical and
chemical characteristics of the water. Some acclimatization
to the presence of zinc is possible. it has also been
observed that the effects of zinc poisoning may not become
apparent immediately, so that fish removed from zinc-
contaminated to zinc-free water (after 4-6 hours of exposure
to zinc) may die 48 hours later. The presence of copper in
water may increase the toxicity of zinc to aquatic
organisms, but the presence of calcium or hardness may
decrease the relative toxicity.
Observed values for the distribution of zinc in ocean waters
vary widely. The major concern with zinc compounds in
marine waters is not one of acute toxicity, but rather of
the long-term sub-lethal effects of the metallic compounds
and complexes. From an acute toxicity point of view
invertebrate marine animals seem to be the most sensitive
organisms tested. The growth of the sea urchin, for
example, has been retarded by as little as 30 ug/1 of zinc.
Zinc sulfate has also been found to be lethal to many
plants, and it could impair agricultural uses.
BStionale_for__Rejection_of_gther__ Was te_ Water
£2£Stituents_as_Pollutant_Parameters
Arsenic
Arsenic is found to a small extent in nature in the
elemental form. It occurs mostly in the form of arsenites
of metals or as pyrites.
*o oiS ?ormally Present in sea water at concentrations
ot 2 to 3 ug/1 and tends to be accumulated by oysters and
other shellfish. Concentrations of 100 mg/kg have been
reported in certain shellfish. Arsenic is a cumulative
poison with long-term chronic effects on both aquatic
57
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organisms and on mammalian species and a succession of small
doses may add up to a final lethal dose. It is moderately
toxic to plants and highly toxic to animals especially as
AsH3.
Arsenic trioxide, which also is exceedingly toxic, was
studied in concentrations of 1.96 to 40 mg/1 and found to be
harmful in that range to fish and other aquatic life. Work
by the Washington Department of Fisheries on pink salmon has
shown that at a level of 5.3 mg/1 of As2O3 for 8 days was
extremely harmful to this species; on mussels, a level of 16
mg/1 was lethal in 3 to 16 days.
Severe human poisoning can result from 100 mg
concentrations, and 130 mg has proved fatal. Arsenic can
accumulate in the body faster than it is excreted and can
build to toxic levels, from small amounts taken periodically
through lung and intestinal walls from the air, water and
food.
Arsenic is a normal constituent of most soils, with
concentrations ranging up to 500 mg/kg. Although very low
concentrations of arsenates may actually stimulate plant
growth, the presence of excessive soluble arsenic in
irrigation waters will reduce the yield of crops, the main
effect appearing to be the destruction of chlorophyll in the
foliaqe. Plants grown in water containing one mg/1 of
arsenic trioxides showed a blackening of the vascular
bundles in the leaves. Beans and cucumbers are very
sensitive, while turnips, cereals, and grasses are
relatively resistant. Old orchard soils in Washington that
contained 4 to 12 mg/kg of arsenic trioxide in the top soil
were found to have become unproductive.
Data on arsenic content of process waste water is very
sparse and a firm conclusion regarding its significance can
not be reached at this time. It is assumed that most of the
arsenic remains with any formed speiss and that all speiss
granulation operations have closed water loops.
Chemical_Oxi£en_Demand
The chemical oxygen demand is a measure of the quantity of
the oxidizable materials present in water and varies with
water composition, temperature, and other functions.
Dissolved oxygen (DO) is a water quality constituent that,
in appropriate concentrations, is essential not only to keep
organisms living but also to sustain species reproduction,
vigor, and the development of populations. Organisms
undergo stress at reduced DO concentrations that make them
58
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less competitive and able to sustain their species within
the aquatic environment. For example, reduced DO
concentrations have been shown to interfere with fiSh
population through delayed hatching of eggs, reduced size
and vigor of embryos, production of deformities in young
interference with food digestion, acceleration ofY£lSod
clotting decreased tolerance to certain toxicants, reduced
snSt.i ^flciency and growth rate, and reduced maximum
sustained swimming speed. Fish food organisms are likewise
affected adversely in conditions with suppressed DO Since
ovv^n iLaqUatlC Or9anisms need a certain amount of
oxygen, the consequences of total lack of dissolved oxygen
due to a high COD can kill all inhabitants of the affected
3.3T€cfc •
If a high COD is present, the quality of the water is
usually visually degraded by the presence7 of decomposing
materials and algae blooms due to the uptake of degraded
materials that form the foodstuffs of the algal populations?
The low concentrations of oil and grease found in the
process waste waters of this industry will minimise the
organic sources of COD. Limitations OnY pH wiS control
ferrous-iron content of effluents. conrroi
Cyanide
Cyanides in water derive their toxicity primarily from
undissolved hydrogen cyanide (HCN) rather than fro£ 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
8^.} *e"^.°i,^^™i? }; *™* - <:»-; ""a 'PHleSS~
87 nr ^ JH a PH °5 9' ^ ^c^' and at a pH of ,
87 percent of the cyanide is dissociated. The toxicity of
"
Cyanide has been shown to be poisonous to humans- amounts
over 18 ppm can have adverse effects. A sinqlS dSsS of
about 50-60 mg is reported to be fatal. Sln9le dose of
aquatic organisms are extremely sensitive to
„ --.
59
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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.
Only nil amounts of total cyanide were reported in the data
collected from documented sources. Check analyses indicated
that the amount of cyanide in the waste water from lead
smelter slag granulation and acid plants, which use mine
water as a source, is of the order of 0.002 rng/1. This
level is considered negligible. Thus, cyanide was excluded
as a significant parameter.
Oil and_Grease
Oil and grease exhibit an oxygen demand. Oil emulsions may
adhere to the gills of fish or coat and destroy algae or
other plankton. Deposition of oil in the bottom sediments
can serve to inhibit normal benthic growths, thus
interrupting the aquatic food chain. Soluble and emulsified
material ingested by fish may taint the flavor of the fish
flesh. Water soluble components may exert toxic action on
fish. Floating oil may reduce the re-aeration of the water
surface and in conjunction with emulsified oil may interfere
with photosynthesis. Water insoluble components damage the
plumage and coats of water animals and fowls. Oil and
grease in a water can result in the formation of
objectionable surface slicks preventing the full aesthetic
enjoyment of the water.
Oil spills can damage the surface of boats and can destroy
the aesthetic characteristics of beaches and shorelines.
Only nil amounts of oil and grease were reported except in
the case of mine input water at Smelter B. The practice of
installing oil and grease skimmers in settling tanks is a
control practice which provides oil and grease pollution
reduction. Where such control devices are absent, oil and
grease might be considered as a parameter subject to control
and treatment.
Temperature
Temperature is one of the most important and influential
water quality characteristics. Temperature determines those
species that may be present; it activates the hatching of
young, regulates their activity, and stimulates or
suppresses their growth and development; it attracts, and
may kill when the water becomes too hot or becomes chilled
60
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too suddenly. colder water generally suppresses
development. Warmer water generally accelerates activity
and may be a primary cause of aquatic plant nuisances when
other environmental factors are suitable.
Temperature is a prime regulator of natural processes within
the water environment. It governs physiological functions
in organisms and, acting directly or indirectly in
combination with other water quality constituents, it
affects aquatic life with each change. These effects
include chemical reaction rates, enzymatic functions,
molecular movements, and molecular exchanges between
membranes within and between the physiological systems and
the organs of an animal.
Chemical reaction rates vary with temperature and generally
increase as the temperature is increased. The solubility of
gases in water varies with temperature. Dissolved oxygen is
decreased by the decay or decomposition of dissolved organic
substances and the decay rate increases as the temperature
vi W^er lncreases reaching a maximum at about 30°C
The temperature of stream water, even during
^ bel°W th! °Ptimum for Pollution-associated
h i Incfeas^n ^e water temperature increases the
bacterial multiplication rate when the environment is
favorable and the food supply is abundant.
Reproduction cycles may be changed significantly by
increased temperature because this function takes place
S? !!?i r*stricted temperature ranges. Spawning may not occSr
at all because temperatures are too high. Thus, a fish
population may exist in a heated area only by continued
oSt.nt?^°n- _D"re9arding the decreased reproductive
potential, water temperatures need not reach lethal levels
to decimate a species. Temperatures that favor competitors,
predators, parasites, and disease can destroy a species at
levels far below those that are lethal. species at
Fish food organisms are altered severely when temperatures
approach or exceed 90<>F. Predominant algal specie^ change?
oraanfL/ T1?1 ,±S decreased' *nd bottom associa?ed
organisms may be depleted or altered drastically in numbers
SuatfcSt^ f ^ Increased wat« temperatures may Sause
favSrabl? nuis^nces when other environmental factors are
Synergistic actions of pollutants are more severe at higher
water temperatures. Given amounts of domestic sewage,
refinery wastes, oils, tars, insecticides, detergents? 2nd
fertilizers more rapidly deplete oxygen in water at higher
61
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temperatures, and the respective toxicities are likewise
increased.
When water temperatures increase, the predominant algal
species may change from diatoms to green algae, and finally
at high temperatures to blue-green algae, because of species
temperature preferentials. Blue-green algae can cause
serious odor problems. The number and distribution of
benthic organisms decreases as water temperatures increase
above 90°F, which is close to the tolerance limit for the
population. This could seriously affect certain fish that
depend on benthic organisms as a food source.
The cost of fish being attracted to heated water in winter
months may be considerable, due to fish mortalities that may
result when the fish return to the cooler water.
Rising temperatures stimulate the decomposition of sludge,
formation of sludge gas, multiplication of saprophytic
bacteria and fungi (particularly in the presence of organic
wastes), and the consumption of oxygen by putrefactive
processes, thus affecting the esthetic value of a water
course.
In general, marine water temperatures do not change as
rapidly or range as widely as those of freshwaters. Marine
and estuarine fishes, therefore, are less tolerant of
temperature variation. Although this limited tolerance is
greater in estuarine than in open water marine species,
temperature changes are more important to those fishes in
estuaries and bays than to those in open marine areas,
because of the nursery and replenishment functions of the
estuary that can be adversely affected by extreme
temperature changes.
Although the maximum discharge temperature of waste water
issuing from domestic smelters was reported to be 130 F in
earlier (1971) Corps of Engineers reports, temperature is
not considered a significant pollution parameter because
such water is now impounded in cooling ponds before it is
released.
Bismuth
Bismuth is a constituent of some lead ores, but there are
insufficient data on which to base pollutant limitations.
It is not ordinarily reported on lead smelter waste water
effluents analyses. Salts of bismuth are virtually
insoluble in water, and because of this, bismuth is excluded
as a significant parameter.
62
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Calcium^ MaqnegJ.UJT
The lead veins in southeastern Missouri are located in a
dolomite (CaC03.MgC03) deposit. Except in the case of
Smelter B, only relatively low amounts of calcium and
magnesium are found in the waste waters of U.S. smelters
smelter B uses mine water which is moderately high in
calcium and magnesium and, thus, requires a softSninq
pretreatment. However, dolomite reacts with lead in basic
solutions to yield insoluble lead carbonate, and it is so
used to recover lead. Its presence, in the relatively low
amounts noted in Section V, augments the effect of lime used
as a control, and in this sense, it might be considered as a
secondary parameter.
Biochejnical_Oxy.q.en_Demand
BOD is not an important parameter in the primary lead
n«£?£jn ^S the • sanitar* effluents, containing
practically all the organic compounds in the total discharge
from the smelters, are now handled separately from process
?«« %*Ta ?' Jt W°Uld be considered as a parameter if the
two effluents were combined.
Dissglved_Chlor ides ^.Fluorides ^.Phosphates. _and_Carhnna*£s
The amount of chlorides in the source water entering U.S.
noSSefn +** x t, and there are n° aPPreciable additions
°JS\l discharge. The amount of fluorides entering
~™ * 5 STr°e ?ater is extremely low, and the measurements
reported show low amounts in the discharge. The phosphate
contents of both source and discharge water are negligible.
Data was also requested on the carbonates; the only reported
S~L J ?H considerable instability in that the amount
present in the source water was reduced to almost half as
nho^h,i« the^ dis^arge. Thus, chlorides, fluoride,
parameter's: carbonates are excluded as significant
Qther__Metals
Other metals for which there were either no available data
on effluent content or the reported effluent concentrations
were insignificant include alurrinum, copper, magnesium
manganese, antimony, chromium, cobalt, iron, nick™'
selenium, silver and tin. Setting effluent limitations on
the prescribed heavy metals, which are the principal
pollutant metals in the process waste waters from the
primary lead industry, and specifying a PH range wi™ in
turn Umit these other trace metals.
63
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SECTION VII
CONTROL AND TREATMENT TECHNOLOGY
Introduction
Specific water usage in primary lead smelters and refineries
was quantitatively discussed in Section V, and the
compositions of waste waters from each smelter were also
characterized. The selection of significant pollution
parameters was discussed in Section VI. This section
presents the control and treatment technology of primary
lead smelter and refinery waste waters.
Wa st e_ Wat er_ Ef f luent s_a nd
In the context of this report the term "control technology"
refers to any practice applied in order to reduce the volume
of waste water discharged. "Treatment technology" refers to
any practice applied to a waste water stream to reduce the
concentration of pollutants in the stream before discharge.
The control technology currently used by the primary lead
industry comprise the following items:
(1) Segregation of water streams (in lead
smelters and refineries these normally
fall into three categories (I) non-
contact cooling water, (2) process water,
and (3) smaller auxiliary, sometimes
intermittent, streams such as cooling
tower or furnace jacket blowdowns, leaks,
etc.);
(2) water conservation techniques (e.q
recycling) ;
(3) Housekeeping provisions (for spills,
leaks, storm water runoff, pond failures,
blowdowns of cooling towers, furnace
jackets, and auxiliary equipment) ;
(4) Special inplant abatement measures.
Process water effluents from primary lead operations include
° 6 ^ ?°urces: <1> a wea* acid bleed from
an acidnl ee from
an acid plant wet scrubber (i.e., acid plant blowdown) , (2)
slag granulation water, and (3) discharges from wet
65
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scrubbers at sinter plants. Current practices vary among
the plants with respect to the segregation of process water
and noncontact cooling water, and the extent to which the
process water is treated, recycled, and discharged. The
quantity of process water usage compared with cooling water
usage is generally small. For this reason, any further
treatment of process water will, in all probability, be
economically benefited by the segregation of process water
and cooling water.
Current methods of treatment and discharges of process water
at four plants (Plant A through D) are shown in Table 16.
In Plant E, all of the process water effluent is recycled,
which results in no discharge of process water.
In each of three plants which have a metallurgical sulfuric
acid plant, the acid plant scrubber is operated with weak
acid recycle and a bleed. The weak acid bleed is
neutralized with lime prior to discharge to the slag
granulation circuit. Plant B limes its acid plant blowdown
and then commingles it with other plant process and
nonprocess waste waters. The two ponds holding this water
provide recycle and reuse capability within the smelter, and
an average discharge of 330 cu m/day (50 gpm) results from
pond overflow. In Plant D, the bleed is discharged to a
treatment plant, where it is mixed with other waste water
streams and then reused and recycled. The quantities of the
weak acid bleed per unit of lead production are fairly
uniform among the three plants. They are: 715 1/kkg (171
gal/ton) at Plant A; 756 1/kkg (181 gal/ton) at Plant B; and
822 1/kkg (197 gal/ton) at Plant D.
Slag granulation water is currently discharged to surface
waters at three plants. All three plants operate partially
closed circuits with recycle and bleed-off. Plant D
operates a once-through granulation system, but this
effluent is lost or consumed in the slag pile and no
discernible water is discharged. Plant C is currently
attempting to reuse the bleed from its slag granulation
water system as a sinter machine offgas coolant prior to
entrance in the sinter baghouse. Plant A is making recycle
changes to its slag granulation system, so that a flow
reduction of from 8,200 cu m/day (1500 gpm) down to 1,640 cu
m/day (300 gpm) will be achieved.
Recycle and reuse of scrubber water is practiced by all four
smelters using such devices. As with its acid plant
blowdown. Plant D treats its scrubber water, commingles it
with other effluents, and both recycles it within the
66
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ath - °nSite PhosPhate fertilizer
plant with no resultant discharge.
JlLh t?6 primarv lead industry, waste water treatment
technology normally involves only chemical treatment. Lime
treatment, with mechanical separation of the resultina
precipitates from the process stream, is the common chemical
treatment practice used by this industry.
Chemical treatment technology is discussed first in this
section, because, regardless of inplant control procedures
"e P
°ne Sinc?le mode of chemical treatment
r^oval of the heavy metal pollutants by
Subse^ent hydroxides and their mechanical
from the process water) .
includedUt?2LParameterS S*lected in tne Previous section
included lead, zinc, cadmium, and mercury, as well as TSS
anu pn.
appearedWaSinnClthed " t P°llutant parameter, because it
appeared in the waste water of a complex ODerat i on
p?antStinL°f b°th-a I6ad Smelter and an -no elec?rolytS
plant. Mercury is associated in significant amounts with
some western and imported lead concentrates.
P°ilutan^s are in solution as sulfates and oxides
contro f63 Smelter waste water. The standard means of
control for removing these pollutants is to precipitate them
with lime additions from basic solution GsingP PH as a
settTin'a >£** *° Separate the Precipitated hydroxides by
settling. The remaining parameter that completes the list
soli^9 CanVP°11Utant parameters ^ total suspended
solids, consisting mainly of granulated slag particles with
some unsettled precipitates. parr.icj.es with
PreciP^ated hydroxides vary;
hydroxide settles very slowly
solubility data. Becau data ained c
equilibria measurements, and even in practical laboratory
67
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0.01
0-001
o.oooi
Figure 6. Theoretical solubilities of metal ions as a
function of pH.(7)
68
-------
experimental work, have not accurately mirrored conditions
in actual practice, they are shown here only to illustrate
the basis for the differences between the effectiveness of
removal of individual pollutants using a relatively narrow
pH range as a means of control. As shown by Figure 6, the
optimum pH for the minimum solubility of cadmium is around
11; whereas, a pH range of 9 to 10 is optimum for minimizing
the solubility of copper, zinc, lead, and nickel. The
minimum solubilities for mercury, arsenic, and antimony are
quite high.
Figures 7 and 8, adopted from West German work on waste
water purification of electroplating solutions, show zinc
and cadmium to have higher minimum solubilities than are
shown in the curves for equilibrium data in Figure 6.
Furthermore, Figure 9, taken from the same West German work,
indicates that cadmium, and to some extent nickel, have
progressively higher minimum solubility values as a function
of standing time (in these experiments, up to 7 hours).
Precipitation with lime is more effective than is indicated
in publications. Concentrations can be obtained that are
much lower than those obtained in theoretical and laboratory
experimental work on single solutions. In the West German
work cited above, coprecipitation of copper and nickel with
chromium resulted in a drastic reduction in the minimum
solubilities of copper and nickel. In a like manner,
coprecipitation and adsorption on flocculating agents, such
as ferrous and ferric sulfates, have a significant effect in
reducing the concentration of the metal ions. In lead
smelter waste waters, isomorphism is another factor which
relates to this effect. As an example, strontium carbonate
is added to zinc sulfate solutions to remove lead from
solution; the resulting strontium sulfate has the same
crystal structure and dimensions as lead sulfate.
On the other hand, there are factors which operate to raise
the minimum solubilities of these heavy metal pollutants.
Dissolved solids, made up of noncommon ions, can increase
the solubility of the metal hydroxides, according to the
Debye-Huckel theory. Sodium sulfate in the lead smelter
waste waters exerts such an effect. Sodium is present in U.
S. lead-smelter waste waters, but not in large amounts.
Also, the presence of complexing agents, such as cyanide,
generally increases the minimum solubilities of metals.
Cyanides were scarcely detectable in the lead smelter waste
waters studied.
Table 17 presents the results of liming and settling of acid
plant blowdown from a primary copper smelter, a primary zinc
69
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mg/1 Soluble Zinc
o
•
o
fD
I
E
8
I
H-
m
o
HI
N
00
o
o
00
(D
U)
o
o
o
Mols/1 Soluble Zinc
-------
1000
100
\ /—Experimental
7 8 9 10 11 12 13
O.Oll
o
2
Figure 8. Experimental solubilities of cadmium.
71
-------
80 r-
70 :
60 -
>
pH = 7.5
— 1,11111
1 1 1 i i i i p
lOOr
80 =
60 -
r-* ,
pH = 8.5
pH = 9.0
1 1 1 1 1 1 i ,/
t *Y
o 20 -
c
N 10 -
0)
pH = 8.0
_ pH = 8.5
— i i 1 1 1 I 1
*f
•§ 20 -
u 10 -
0)
>— 1 /w
-1 * . . . - u 4 0
-Q 1
rH 1.6
O
w 1.2
rH
6 0.4
0
/ f
, _ pH . = 9.0
_ pH = 9 . 5
— pH = 10.1
1 1 I J i 1 l
o 3.0
^ 2.0
g i.ol
)
n ?
012345678
C
Standing time, hours
t
pH = 9.5
l I 1 1 1 1 1 ,
— y
-^ " pH = 10.0
i_ 1 1 1 i
-^ pTT=-TO.!>
^- — '
1 I 1
) 123 4 5 67 8
Standing time, hours
ZINC
16
1 A
14
12
% 10
-------
smelter, and a primary lead smelter. Input dissolved metal
concentrations are not identical for each of the three
cases. output concentrations are generally within the same
range.
n.™ treatment facility at one domestic
primary lead-zinc complex is currently being lined-out.
This new facility will treat the total plant waste water
which includes a periodic discharge from the lead smelter
during settling pond clean-out, process waste water from the
primary zinc plant (4060 cu m/day (745 gpm) ) . and the waste
nr^-«m ^ plant's integrated mining and milling
operations. The anticipated concentrations of selected
process waste water pollutants from this facility are as
toilows:
Process Waste Water Concentration
TSS 60
C<3 0.5
H9 0.006
^ 1.0
Zn 1.7
Plant personnel report that this new treatment facility is
currently operating above its anticipated expectations.
Mditional_Treatment_TechnoloqY
Additional treatment methods, which could be employed for
further reduction of pollutants from proceis water
discharges include (1) hydrogen sulfide treatment, 12)
reverse osmosis, (3) evaporation, and (4) chemical fixation.
Hydrogen sulfide treatment would be an effective method for
metals SS sulfi^ precipitates, which
e?tr?m?1y low solubility. Solubilities of
typical heavy metals found in the waste
Tabe 18 5?g^ ll°m t2?e P^mary lead industry are shown in
*? in „ iSCe the.solub^ities of the sulfides are higher
at low PH, the precipitation reaction should be carried out
at a neutral or alkaline pH.
73
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TJ03LE 18. SOLUBILITY OF METAL SULFIDES
Solubilityf
Metal Neutral Solution Low pH
Ni < 1 100,000
Cd < 1 5,000
Pb < 1 70
Cu < 1 < 1
Hg < 1 < 1
74
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Reverse Osmosis
s?r^me °Sm°sis (*0) is a Process whereby a waste water
2nnn • f PaSSSd at Pressures from 34 to 136 atm (500 to
2000 psia) over a membrane. The membrane is cast from a
solution of cellulose acetate and has the property or
allowing passage of water through the film, but ?ejec?iSa
ions. The permeate is almost completely of ionic ma^eriS
r'h ™ S. ?
ssr ',»
chemically or by evaporation. treated further,
Evaporation
ultlple. effe« evaporation/
^^ ° H
T
distillaion proess
suspended soli§s°?o mini eooofha
evaporation using a separate evaDorifo? £ by comPlete
means such as chlmica/ftxatiSn? ? ' Or by S°me other
75
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Disposal of process waste water by means of solar
evaporation is an excellent treatment method, especially in
climatic areas of net evaporation.
Chemical ^Fixation
rhPmical fixation is a process for detoxifying hazardous
liquid wastes £y means of reaction of chemical additions
with the waste material to form a chemically and
mechanically stable solid. The process can be used for the
chemical fixation of polyvalent metal ions in stable and
SSSSble inorganic compounds Monovalent catxons and »any
anions are physically entrapped in the matrix structure
Resulting from the reaction process. Chemical fixation is
cos'tly Shen compared with the treatment methods Discussed
thus far and probably would rarely be used for Directly
treating the large volume of process waste water effluents
from She primary lead operation. The process, however,
might prove useful and economic for the ultimate disposal of
concentrated liquor wastes generated from reverse osmosis
and evaporative treatment of waste water.
76
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SECTION VIII
COSTS, ENERGY, AND NONWATER QUALITY ASPECTS
Introduction
This section deals with the costs associated with the
various treatment strategies available to the primary lead
industry to reduce the pollutant load in the
°ther
Data on capital costs and on operating costs for present
control and treatment practices were obtained from selec?2d
lead smelters. These data were modified in the followina
way to put all costs on a common basis. following
(1) J^S??1**1 COStS rePorted were changed
to 1971 dollars by the use of the
Marshall and Swift Index (quarterly values
ot this index appear in the publication
McGraw Hill) .
(2) The annual costs were recalculated to
reflect common capitalized charges. To
do this, the annual costs were calculated
by using a factor method as follows:
Operating and maintenance - as reported
by the lead smelters,
Depreciation - 5 percent of the 1971
capital,
Administrative overhead - U percent of
operating and maintenance,
S?e^Y ^and insurance - 0.8 percent
of the 1971 capital,
Interest - 8 percent of the 1971 capital,
Other - as reported by the smelters.
Treatment cost study was performed on five of th- seven
existing primary lead plants. The two plants excluded rrom
77
-------
the cost study include one primary smelter, located in the
Southwest, where the arid climate permits no discharge of
process waste water pollutants by means of solar
evaporation, and one lead refinery, where the use of water
is confined to indirect (noncontact) cooling only.
The treatment costs associated with the present practices
were obtained directly from four of the five smelters. For
the fifth smelter, the costs were estimated on the basis of
the treatment process description and equipment
specifications supplied by the plant. The costs associated
with additional waste water treatment beyond the current
practices were estimated by using published cost data rather
than using the cost data supplied by the smelters. This
approach was considered necessary in view of the fact that
either the pertinent cost data were not available from the
smelters or the reported plant cost data show substantial
variation owing to the differences among the smelters with
respect to water usage and treatment and cost reporting
procedures.
The cost data for the present waste water practices in the
primary lead industry are summarized in Table 19. The
variation in the cost data reflects the difference among the
smelters with respect to smelter operation (e.g., the
presence or absence of an acid plant as part of plant
operation) , extent cf plant water circuit modification,
water usage, and waste water treatment practices, and cost
reporting procedures employed. Ihe higher costs shown in
Table 19 are for those three smelters operating a
metallurgical sulfuric acid plant.
Plant_A
Operations at this plant include the smelting of lead
concentrates, refining, and a metallurgical sulfuric acid
plant. waste water treatment costs were developed from the
costs data supplied by the plant.
Water Usage, Treatment^ and Discharge. A simplified
flowsheet of the plant water circuit is shown in Figure 10.
Plant water is supplied from a well. The discharge from
this plant is an overflow from a cooling pond located within
78
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TABLE 19 . CAPITAL AMD OPERATING COSTS OF PRESENT PROCESS WASTE
WATER TREATMENT PRACTICES IN PRIMARY LEAD INDUSTRY
1 — ' _ ,
Annual Lead
Plant Production,
Designation kkg
(tons)
A 208,610
(230,000)
B 120,963
(133,366)
C 97,956
(108,000)
D 120,948
(133,349)
E 58, 048
( 65,000)
Capital Costs
Total, $ $/Annual kkg
($/ Annual Ton)
208,500 1.00
(0.91)
335,600 2.77
(2.50)
112,700 1.15
(1.04)
472,000 3.90
(3.54)
53,400 0.92
(0.83)
Operating Costs
Total, $/year $/kkg
($/ton)
79,000 o.38
(0.34)
191,500 1.58
(1.43)
52,900 0.54
(0.49)
114,600 0.94
(0.86)
40,000 0.70
(0.63)
Comments
Acid plant
Slag gran.
Acid plant,
ilag gran.
Slag gran.
Acid plant,
Slag gran.
Speiss gran.
• — _ _ —
(a) Lead Bullion
-------
Scrubber
Bleed-off
Overflow
Discharge
to River
00
o
Indirect Cooling Water
Sinter
Plant
(Gas Cooling
Blast Furnace
and Refinery
(Indirect
cooling)
L:
Cooling
Tower
Recycle
Hot
Pond
Sinter Plant
Ventilation
Scrubber
Figure 10. Flow sheet for water circuit at Plant A.
-------
the slag granulation circuit. Water usage at this plant
includes that in the acid plant, blast furnace, refinery,
blast furnace slag granulation, and wet scrubbing of sinter
plant ventilation gases.
Water to the acid plant is supplied from the well. Water is
used in the acid plant for gas cleaning by a wet scrubber
and for indirect cooling. The scrubber water is recycled
between the scrubber and a cooling tower with a bleed-off,
which is passed through a limestone-lined pit to the slag
granulation system. Most of the indirect cooling water is
discharged to the slag granulation system, and the remainder
is discharged to the blast furnace and refinery cooling
system.
Slag granulation water is recycled in a partially closed
circuit between the granulation process and a cooling pond.
The overflow from this cooling pond is currently estimated
at 8,230 cu m/day (1500 gpm) and is discharged to a river.
The present practices for this smelter include internal flow
revisions to reduce the discharge to 1,640 cu m/day (300
gpm) .
Treatment Costs of the Present Practice. Capital and
operating cost data were furnished by the plant for the
current treatment practice (i.e., 1,640 cu m/day (300 gpm)).
The cost data are summarized below:
Basis: Production = 208,610 kkg/yr
(230,000 tons/yr) refined lead
Caeital_Costsi 1971_Dollars
Slag granulation system 48,UOO
Sinter plant ventilation scrubber
recycle 53,200
Plant water circuit revisions,
including ancillary equipment _i££.t22P_
Total Capital Costs $208,500
$/ Annual kkg (ton) 1.00 (0.91)
Raw Materials Nominal
81
-------
Operating and maintenance $48,400
Administrative overhead 1,900
Depreciation 10,400
Interest 16,600
Tax and insurance 1^700
Total Operating Costs $79,000
$/kkg (ton) 0.38 (0.34)
Plant B
This plant supplied fairly complete data on the plant water
circuit and waste water treatment costs. An acid plant is
included as part of the smelter operation at this plant.
Water Usac^ Treatment^ and pis charge. A simplified
flowsheet of the plant water circuit is shown in Figure 11.
Plant water is supplied from a well and a reservoir.
Discharges from the plant include overflows from two cooling
ponds (designated as No. 1 and No. 2).
Indirect cooling water used in the blast furnace, sinter
plant, and casting operation is cooled in a main cooling
tower and recycled. The cooling tower blowdown goes to a
settling pit located in the slag granulation circuit.
Cooling water makeup is provided from the fresh water
supply, the No. 1 cooling pond, and the acid plant as
indicated in the flowsheet.
Slag granulation water is recycled between the granulation
process and a settling pit and between the latter and the
No. 1 cooling pond. An overflow from the latter pond is
discharged to a river.
In the acid plant operation, the effluent from a packed
tower scrubber goes to a lime sump for neutralization.
Indirect cooling water is partially recycled through a cool-
ing tower. The remainder of the indirect cooling water is
discharged to the No. 2 cooling pond. The acid plant blow-
down is treated in the lime sump. An overflow from the lime
sump provides makeup water for the slag granulation circuit
via the settling pit located in that circuit. The remainder
of the lime sump effluent is discharged in succession to
a
82
-------
Blast Furnace
and Sinter
Plant
(Indirect Cool
(Indirect
Cooling)
Slag
Granulation
Indirect Cooling
Indirect
Cooling
Discharge
to
River
Figure 11. Flow sheet for water circuit at Plant B.
83
-------
lime bed and to the No. 2 cooling pond. An overflow from
the latter pond is discharged to a creek.
An average discharge from both ponds is about 273 cu m/day
(50 gpm) and is much lower during dry seasons.
Water employed in a wet scrubber is treated in a closed-loop
circuit using a settling basin as indicated in the
flowsheet.
Treatment Costs for Present __ Practices. The capital cost
data "supplied by the plant and updated to 1971 costs are
summarized below by treatment circuits keyed to the plant
operations:
Basis: Production = 120,963 kkg/yr
(133,366 tons/yr) refined lead
Casting operation cooling unit 7,200
Slag granulation circuit 232,000
Acid plant lime neutralization
system 2U,800
Wet scrubber settling basin 20,000
Cooling Pond No. 1 36,000
Cooling Pond No. 2 __ 15,600
Total Capital Costs $335,600
S/Annual kkg (ton) $2.77 (2.50)
Operating cost data supplied by the plant were available
only for the consumption of lime for the acid plant effluent
neutralization circuit, which is estimated at 113.5 kg/hr
(250 Ib/hr) , and for the operating labor requirement
specified at 2 men/shift. The remainder of the annual cost
items were estimated. Operating costs are summarized below:
pperating^Costsi
Raw materials (lime) 27,400
Utilities Nominal
84
-------
Operating labor 87,600
Maintenance 24,700
Administrative overhead 4,500
Depreciation 17,800
Interest 26,800
Tax and insurance 2.cZ.P_9.
Total Operating Costs $191,500
$/kkg (ton) 1.58 (1.43)
Plant C
This plant is engaged in smelting and refining operations.
No acid plant exists at this smelter.
Water ysagex Treatment^ and Discharge. A simplified
flowsheet of the plant water circuit is shown in Figure 12.
The plant water is supplied from a well and a lake. The
discharge from the plant is an overflow from two settling
ponds located in the slag granulation circuit.
Indirect cooling water is used for the blast furnace,
refining, casting, and various other process equipment, such
as baghouse fans and air compressors. The cooling water to
the blast furnace is totally evaporated.
The cooling water used in the refinery and casting
operations are recycled using a sump. The same sump also
receives the cooling water from the process equipment. An
overflow from the sump is used for cooling the blast furnace
and the sinter plant gases and is totally evaporated into
the gas streams.
Slag granulation is currently practiced in a partially
closed circuit. A bleed-off from the circuit is discharged
to two settling ponds, both of which overflow into a creek.
Two cooling towers are included in the slag granulation
system to provide cooling. Immediate plans for this system
include the usage of this small discharge as a gas cooling
media prior to passage through the sinter offgas baghouse.
85
-------
Evaporation
oo
Blast Furnace
(Indirect
Cooling)
Refining and
Casting
(Indirect
Cooling)
Process
Equipment
Cooling
(Indirect)
Slag
Granulation
System
Evaporation
Recycle
Sump
Settling
Ponds (2)
Blast Furnace
and Sinter
Plant
(Gas Cooling)
.
'
/ Planned
reuse as sinter
cooling media
Discharge
to
Creek
Figure 12. Flow sheet of water circuit at Plant C.
-------
Treatment Costs of Present Practice. Treatment costs for
this plant were estimated on the basis of treatment process
description and equipment specifications supplied by the
plant. The cost data are summarized below:
Basis: Production = 97,956 kkg/year
(108,000 tons/year) refined lead
1971_Dollars
Slag granulation water recycle 112^7,00
Total Capital Costs
$/Annual kkg (ton)
Operating Cgsts^
Raw materials
Utilities
Operating labor, $5/hr,
2 men/day
Maintenance
Administrative overhead
Depreciation
Interest
Tax and insurance
Total Operating Costs
$/kkg (ton)
$112,700
1.15 (1.04)
$/Year
Nominal
Nominal
29,200
6,800
1,400
5,600
9,000
900
$52,900
0.54 (0.49)
Plant_D
This plant includes, besides a lead smelting and refining
operation, a primary electrolytic zinc plant, a phosphate
fertilizer plant, and an ore concentrating and mining
operation. The plant is currently in the process of
extensive modification of water usage and waste water
treatment with the installation of a new central waste water
treatment plant to serve the entire plant complex. The
modification is scheduled to be completed in 1974. The cost
87
-------
analysis for this plant was, therefore, based on the
modified plan for water usage and treatment.
er Usaaex Treatment ^ and Discharge. The water usage,
treatment, and discharge are shown in Figure 13 for the lead
smelting and refining operation (referred to as the
smelter) . Feed water to the smelter consists of fresh water
supplied from the main plant reservoir, cooling water from
the zinc plant, and recycle water from the lead smelter's
internal treatment plant.
Slag granulation water proceeds with the slag to the slag
pile where it is totally consumed, and no known discharge to
navigable water occurs. Acid plant blowdown, baghouse
cleaning water, and scrubber water are combined and treated
in the lead smelter's internal treatment plant, consisting
of lime precipitation, thickening, and filtration. Most of
the resulting overflow is recycled back to the lead smelter
reservoir. About 2,180 cu m/day (400 gpm) of this overflow
is reused within the plant's phosphate fertilizer operation;
this fertilizer plant operates in a closed-water circuit
mode with a segregated portion of the central impoundment
area. The remaining discharge from the lead smelter's
internal treatment plant is periodic in nature and occurs
during cleanout of the internal treatment plant's pond.
During cleanout, the pond's volume is discharged to the
central impoundment area, where it commingles with effluents
from the primary electrolytic zinc plant and from the ore
mining and concentrating operations.
The waste water collected in the central impoundment area is
treated in the central treatment plant by lime precipitation
and thickening. The underflow sludge from the thickener is
returned to the central impoundment area and the overflow
(clarified water) is partially reused in the plant
concentrator, with the remainder discharged to a creek.
§25§i£e£ Treatment Facilities C2§t§. The waste water
treatment facilities at the"" smelter include the lime
precipitation plant, the settling pond, the main reservoir,
and associated piping, pumps, and other auxiliary equipment.
The capital and operating costs were estimated as follows
using the cost data supplied by the plant:
Basis: Production = 120,950 kkg/year
(133,349 tons/year) refined lead
88
-------
Zinc Plant
Reservoir
Overflow
+ Make-up
oo
VD
Internal
Lead
rreatment
PI a«<-
Periodic Pond
Clean-out
Discharge
Final
^"Discharge
to Creek
Closed-
Circuit
Figure 13. Flowsheet of water circuit at Plant D.
-------
C ap it a 1 _Co s t s^
Total Capital Costs $286rOOO
I/Annual kkg (ton) 2.36 (2.14)
Qperating_Costs^
Total Operating Costs $ 99,000
$/kkg (ton) 0.82 (C.74)
Central Treatment Plant Costs... The central treatment
facilities include the central impoundment area and the
central treatment plant for lime precipitation. As pointed
out previously, the treatment complex is designed to serve
the integrated plant operation, of which the lead smelter is
a part. The capital costs of the central treatment
facilities associated with the smelter operation include:
(1) the retrofit costs for the smelter, (2) the cost of the
central impoundment area apportioned to the smelter, and (3)
the cost of the central treatment plant apportioned to the
smelter. Since only the total costs are known or can be
calculated for the latter two items, the costs associated
with the smelter were estimated by apportioning the total
costs by the ratic of the waste water discharge from the
smelter to the central impoundment area and the total waste
water input to the central impoundment area. The only
discharge from the lead smelter to the central impoundment
area occurs when the smelter's internal treatment pond is
periodically emptied for clean-out. Plant D personnel
estimate this flow to average around 576 cu m/day (105 gpm) .
The total flow to the central treatment plant from the
central impoundment area is 27,800 cu m/day (5,100 gpm),
which consists of 576 cu m/day (105 gpm) average from the
lead smelter; 4,060 cu m/day (745 gpm) from the zinc plant;
6,660 cu m/day (1,210 gpm) mill waters; and 16,600 cu m/day
(3,040 gpm) mine drainage water.
Under the above assumption, the capital and operating costs
for the smelter portion of the central treatment plant were
estimated as follows:
Basis: (a) Production = 120,948 kkg/year
(133,349 tons/year) refined lead
(b) Lead smelter/total plant input =
105/5,100 = 0.02.
90
-------
Capital Costsj^
Central Treatment Plant
Total
Smelter portion
Central Impoundment Area
Total
Smelter portion
Smelter retrofit costs
Total smelter
$/Annual kkg (ton)
Operating Costs:
Central Treatment Plant
Total
Smelter portion
Central Impoundment Area (Smelter Portion)
Maintenance $ 700
1971 Dollars
$518,000
$ 11,000
$644,000
$ 13,000
$162,000
$186,000
1.54 (1.40)
$/Year
$656,000/year
$ 13,000/year
Depreciation (straight
line over 17-year life)
Tax and insurance
Interest
$
$
800
100
$ 1^.000
$ 2,600
Total Operating Costs $ 15,600/year
$/kkg (ton) 0.13 (0.12)
Total Costs for the Present Treatment Practice. The total
capital and operating ccsts for" the "present" treatment
practice were estimated by adding the costs associated with
the smelter treatment facilities and the central treatment
facilities:
91
-------
Capital costs $472,000
S/Annual kkg (ton) 3.90 (3.54)
Operating Costs $114,600/year
$/kkg (ton) 0.94 (0.86)
Plant E
This plant is engaged in smelting operations only. No
refining or acid plant operations are involved.
Watgr Usa^e^ Treatment^ and Discharge. A simplified
flowsheet of the plant water circuit is shown in Figure 14.
The plant water is supplied from a reservoir, wnich also
serves as a cooling pond. Water usage at this plant can be
categorized by indirect cooling and process water. Indirect
cooling water is used on a once-through basis in the blast
furnace, the sinter plant, and the dross reverberatory
furnace and is then combined and cooled in a cooling tower
and discharged to a creek. Cooling water used in the slag
fuming furnace is returned to the reservoir.
Process water is used in the granulation of speiss, produced
from the dross reverberatory furnace, and spray conditioning
of sinter plant flue gas for an electrostatic precipitator.
The effluents from these two operations are recycled in
closed circuits using a settling pond and settling sumps as
indicated in the flowsheet.
Treatment costs of Present Practice. Capital costs for
the treatment processes as described above were estimated by
using the cost and equipment data supplied by the plant.
Cost data and calculations are summarized below:
Basis: Production = 58,048 kkg/year
(64,000 tons/year) lead bullion
Cap_ital_Costs_:. 1971 Dollars
Speiss granulation water recycle $27,400
Electrostatic precipitator gas conditioning
spray recycle $26^000
Total Capital Costs $53,400
92
-------
Reservoir
(Cooling Pond)
co
Recycle
Zinc Fuming
Furnace
(Indirect
Cooling)
Blast Furnace
(Indirect
Cooling)
Sinter Plant
(Gas Cooling
and Indirect
Cooling)
Reverberatory
Furnace
(Indirect
Cooling)
Speiss
Granulation
Cottrell
Gas
Conditioning
Sprays
Indirect
Cooling
Indirect
Cooling
Indirect
Cooling
^Discharge to
Creek
Recycle^
Recycle
Fiqure 14. Flow sheet of water circuit at Plant E.
-------
$/Annual kkg (ton) 0.92 (0.83)
QEeration_Costs.:. $/Year
Raw materials
Utilities
Operating labor
Maintenance
Administrative overhead
Depreciation
Interest
Tax and insurance
Total Operating Costs
$/kkg (ton)
jEcononjics_of_Additional^COQtrol and
"~ Treatment Practicgs
Of the seven primary lead facilities currently operating in
the United States, five plants, by virtue of either the
current control and treatment practices or the lack of
process waste water at these plants, meet the proposed
effluent limitations guidelines derived in this development
document. These five plants, therefore, are not
economically impacted by the proposed limitations.
The economics of the necessary additional control and
treatment practices for the two remaining primary lead
operations are discussed in the ensuing paragraphs.
Plant_A
Current control and treatment technology used by Plant A
allows the final discharge of 1,6UO cu m/day (300 gpm) of
process waste water after usage for slag granulation. This
effluent contains acid plant blcwdown. The proposed
effluent limitations for Plant A (this plant is
geographically located in an area of net precipitation) are
94
-------
based upon a selected discharge flew rate of 835 1/kkg (200
gal/ton) and treated process waste water pollutant
concentrations after liming and settling. One alternative
for achievement of the proposed limitations for this plant
is to reduce the plant discharge by further recycle or reuse
until the selected discharge flow rate is achieved, and then
use a lime and settle treatment facility.
Based upon an annual production rate of 208,610 kkg/yr
(230,000 tons/yr) and the selected discharge flow rate of
835 1/kkg (200 gal/ton), Plant A's discharge should be about
545 cu m/day (TOO gpm). Cost estimates for pumping and
piping the additional recycle water are not currently
available, nor are economic estimates for reuse of such a
volume. In order to obtain an approximation of these costs,
cost estimates for artificial evaporation will be used on
the 1,090 cu m/day (200 gpm) flow reduction. These costs
should represent the iraximum costs seen through recycle and
reuse control alternatives.
£a£ital_Costs ,1971, Dollars
Control alternatives $1,084,000
Qger.ating Costs _$/year
Operating and maintenance $ 132,000
Fuel 165,000
Depreciation 54,000
Taxes and insurance 22,000
Interest _109A000_
Total Operating Costs $ 482,000
The costs for treating the resultant 545 cu m/day (100 gpm)
of process waste waters prior to release to navigable waters
by lime and settle are estimated as follows:
Ca£ital_Costs liII_Pollars
Lime and settle treatment plant $150,000
Operating Costs . $/year
Operating and maintenance 53,200
95
-------
Depreciation 7r50C
Taxes and insurance 3,000
Interest JL5XOGO
Total Operating Costs $ 78,700
The total estimated costs for Plant A to achieve compliance
to the recommended limitations are:
Total Capital Costs $1,234,000
$/Annual kkg 5.90
($/Annual ton) (5.37)
Total Operating Costs $ 560,700
$/kkg ($/ton) 2.68 (2.44)
These costs are considered to represent the upper limit of
control costs, since the costs of artificial evaporation
were used to approximate the unknown costs of recycle and/or
reuse.
Plant B
The current discharge of process waste water from this
primary lead smelter is reported to be 273 cu m/day (50
gpm). This plant is geographically located in an area of
net precipitation, so the selected discharge flow rate of
835 1/kkg (200 gal/ton) can be used to calculate this
plant's discharge. For a production rate of 120,963
kkg/year (133,366 tons/year), this plant's discharge should
be about 300 cu m/day (55 gpm). Therefore, liming and
settling the resultant 273 cu m/day (50 gpm) will provide
compliance to the proposed limitations. Effluent
concentration data from Plant B are contained in Table 14
and indicate high discharge values of cadmium. The primary
reason for these high values was due to an untreated sinter
plant spray chamber discharge entering one of the holding
lakes, from which the final discharge occurs. Recently,
plant personnel feel that this problem has been solved by
the installation of a dry electrostatic precipitator.
Company personnel also feel that their currently used lime
96
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pit should be either modified or replaced with a new liming
system. Estimates of this replacement or modification are:
Ca£ital_Costs 1 97 1_ Dollars
Modified or replaced liming system $ 41,000
S/Annual kkg $0.34
($/Annual ton) ($0.31)
Operating Costs _$/£e.ar_
(Assume 25% of capital) $ 10, 000
$/kkg $0.08
($/ton) ($0.07)
Total_Costs_
, estimated costs to Plants A and B, on the basis of
1971 dollars, are $1,275,000 capital and $570,700 operating,
most of which is attributable to additional treatment and
control technology at Plant A. These values are lifted in
Table 20.
Specific data on energy requirements were not available from
most of the plants surveyed. The current waste water
treatment practices are confined to cooling towers, settling
ponds, and lime treatment, which require an insignificant
amount of electrical and thermal energy relative to total
plant operations. Data supplied by Plant D on a lime
treatment process located in the sirelter plant indicate a
power consumption estimated at about 5 kwhr/kkg (4 5
kwhr/ton) of lead produced. Power requirements for Plant
?«« total cornPle* liir.e and settle treatment plant are about
100 horsepower, or the equivalent of much less than 1
percent of total plant energy consumption.
97
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TABLE 20. ADDITIONAL CONTROL AND TREATMENT COSTS (1971 DOLLARS)
Plant
Designation
Additional Additional
Control and Treatment Capital $/Annual kkg
Practice Cost ($/Annual Ton)
Additional
Operating
Cost
$/kkg
($/ton)
CO
Further Reuse and
Recycle and lime and
settle
$1,234,000
$5.90
(5.37)
$560,700
2.68
(2.44
B
Modify or Replace
Liming System
$ 41,000
0.34
(0.31)
10,000
0.08
(0.07)
None
D
None
E
None
None
TOTAL
$1,275,000
$570,700
-------
Solid_Waste_Gener ation
Lime treatment processes will produce solid waste in the
form of dewatered sludge containing calcium sulfate and
metal hydroxides. The quantity of sludge produced on a
CaSO4 basis was estimated at 20 kg/kkg (40 Ib/ton) of lead
production based upon data supplied by Plant B on lime
consumption in neutralization of acid plant scrubber bleed.
Sludge production is small and can be disposed of by
numerous means such as by reuse as a sinter-feed constituent
or as an input to the zinc fuming plant. Disposal to either
the slag pile or to tailings pond (Plant D) is also
possible. In comparison to the mass generation of slag, the
production of solid waste through water pollution control is
nearly negligible.
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SECTION IX
BEST PRACTICABLE CONTROL TECHNOLOGY CURRENTLY
AVAILABLE—EFFLUENT LIMITATIONS GUIDELINES
Introduction
The effluent limitations that must be achieved by July I,
1977 are to specify the degree of effluent reduction
attainable through the application of the best practicable
control technology currently available. Such control
technology is based on the average of the best performance
by plants of various sizes and ages, as well as the unit
processes within the industrial category. This average is
not based upon a broad range of plants within the primary
lead industry, but upon the performance levels achieved by
the exemplary plants. Additional consideration was also
given to:
(1) The total cost of application of
technology in relation to the effluent
reduction benefits to be achieved
from such application.
(2) The size and age of the equipment and
plant facilities involved.
(3) The process employed.
(4) The engineering aspects of the
application of various types of
control techniques.
(5) Process changes.
(6) Nonwater quality environmental
impact (including energy requirements).
The best practical control technology currently available
emphasizes effluent treatment at the end of a manufacturing
process. It includes the control technology within the
process itself when the latter is considered to be normal
practice within the industry.
A further consideration is the degree of economic 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
or treatment facilities.
101
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Indugtr^_Catec[orY_and Process Waste Waters
The primary lead industry as defined herein includes that
segment of the nonferrous metals industry which extracts
and/or refines metallic lead from ores and concentrates
containing lead as the principal valuable metal. For the
purposes of recommending effluent limitations guidelines,
the primary lead industry is considered as a single
subcategory of point sources of process waste waters. The
rationale for this categorization has been developed in the
previous sections of this document as being principally
based on a nearly uniform pattern of water use and discharge
of process waste waters, including similarities in the
factors of processes, production process waste water
characteristics, and current practices in control and
treatment of process waste water pollutants.
Plant location is considered to have a bearing on specific
limitations for this subcategory. Two of the currently
operating seven primary lead facilities are geographically
located in arid regions, providing a means for process waste
water disposal through solar evaporation. One of the seven
operations, a primary lead refinery, not located on-site
with a primary lead smelter, is net considered as part of
the primary lead subcategory since, due to process, no
process waste water pollutants (as defined for this
subcategory) are produced at this facility.
The sources of process waste water from the primary lead
industry include acid plant blowdown, slag granulation, and
wet scrubber bleed streams. Storm water runoff which
commingles with process waste water is also considered as a
process waste water.
Eiifflary. Lead Facilities Geographically, Located in Areas of
N§t Evaporation
The recommended effluent limitation based on the application
of the best practicable control technology currently
available is no discharge of process waste water pollutants
to navigable waters.
102
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The achievement of this limitation by use of control and
treatment technologies identified in this document leads to
the complete recycle, reuse, or consumption of all water
within the combined processes of the industry with an
associated result of no discharge of water.
Since some primary lead facilities are geographically
located in areas of heavy rainfall event, the following
discharge provisions are proposed as part of the BPCTCA
effluent limitations:
A process waste water impoundment which is designed,
constructed and operated so as to contain the
precipitation from the 10 year, 24 hour rainfall event
as established by the National Climatic Center, National
Oceanic and Atmospheric Administration, for the area in
which such impoundment is located may discharge that
volume of process waste water which is equivalent to the
volume of precipitation that falls within the
impoundment in excess of that attributable to the 10
year, 24 hour rainfall event, when such event occurs.
During any calendar month there may be discharged from a
process waste water impoundment either a volume of
process waste water equal to the difference between the
precipitation for that month that falls within the
impoundment and the evaporation within the impoundment
for that month, or, if greater, a volume of process
waste water equal to the difference between the mean
precipitation for that month that falls within the
impoundment and the mean evaporation for that month as
established by the National Climatic Center, National
Oceanic and Atmospheric Administration, for the area in
which such impoundment is located (or as otherwise
determined if no monthly data have been established by
the National Climatic Center).
Any process waste water discharged pursuant to the above
paragraph shall comply with each of the following
requirements:
Effluent limitations
Effluent Average of daily
characteristic Maximum for values for 30
any 1 day consecutive days
shall not exceed
103
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Metric units tma/11
TSS
Cd
Pb
Zn
pH
50
1
1,
10
25
0.
0,
Within the range 7.0 to 10.5
English units (ppm)
TSS
Cd
Pb
Zn
50
1.0
1.0
10
25
0.5
0.5
5
Within^the range 7.0 to 10.5
When commingled waters are contained in the impoundment
area, the volume of water allowably discharged to
navigable waters due to the conditions of the above
paragraphs will equal the volume calculated on the basis
of the ratio of process waste water volume and total
impoundment volume.
Net Rainfall
L§£d Facilities Geoc[rap_hicallY Located in Areas of
The recommended effluent limitations based on the
application of the best practicable control technology
currently available for primary lead facilities
geographically located in areas cf net rainfall are:
Effluent
characteristic
Effluent limitations
Maximum for
any 1 day
Average of daily
values for 30
consecutive days
shall not exceed
TSS
Cd
Pb
Hg
Zn
pH
Metric units (kilograms per 1,000 kg
of
0.042
0.0008
0.0008
8.0x10-*
0.008
0.021
0.0004
0.0004
4.0x10-6
0.004
Within the range 7.0 to 10.0
104
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English units (pounds per 1,000 Ib
gf^product)
TSS 0.042 0.021
Cd 0.0008 0.0004
Pb 0.0008 0.0004
Hg 8.0x10-6 4.0x10-6
Zn 0.008 0.004
pH Within the range 7.0, to 10.0
Idgntificatign and_Rationale of Best Practicable Control
Technology^Currently_Ayailablg
The prior sections of this document have presented
information on current discharges cf process waste water
from primary lead facilities, consisting of waste water from
slag granulation, scrubber applications, and acid plant
operations. Further, it has been observed that two of the
seven currently operating plants discharge process waste
water from their slag granulation-acid plant blowdown
circuit.
At two shelters operating metallurgical sulfuric acid
plants, the blowdown from the acid plant is used as part of
the slag granulation water input. At differing degrees of
recycle, a discharge from the slag granulation circuit
occurs. The third smelter which operates an acid plant for
sulfur-value recovery on sinter machine offgases recycles
and reuses all of its process waste waters in integrated on-
site operations. The one Missouri smelter, currently
operating without an acid plant, plans to recycle and reuse
all of its slag granulation water with no resultant
discharge of process waste water. Some slag granulation
water will be used as a cooling media for the hot smelter
gas streams prior to entrance into the baghouse. Two
smelters are located in areas of net evaporation, and any
generated process waste water can be disposed of by means of
solar evaporation, after maximumizaticn of recycle and
reuse.
The recommended effluent limitations are based on reported
flow and concentration data. The discussion of water
circuits and flows in Sections VII and VIII of this document
developed the calculated rates of acid plant blowdown for
the three existing acid plants as 715 1/kkg (171 gal/ton),
756 1/kkg (181 gal/ton), and 822 1/kkg (197 gal/ton). The
latter value was applied for the development of the
recommended effluent limitations. One of the elements of
the rationale for the recommended guidelines is the intent
105
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to make the guidelines compatible with air pollution control
requirements. Of the six primary lead smelters currently
operating, three have permanent SO2 control by means of the
conventional metallurgical sulfuric acid plant. In
anticipation of those three smelters, which do not currently
have permanent control, but may shortly, due to air
pollution regulations, the effluent limitations prescribe a
volumetric discharge for an acid plant blowdown. In
accordance with this regulation, two of these three smelters
(with no permanent S02 control) would be required to comply
to a no discharge of process waste water pollutants
guideline, based upon geographical location. The third
smelter, located in Missouri, would be allowed a discharge
of acid plant blowdown in accordance with the recommended
limitations, as identically applied to the other two primary
smelters in Missouri, both of which currently operate
metallurgical acid plants.
The concentrations of selected pollutant parameters applied
to develop the guidelines were selected from available data
on effluents as contained in documents of record, field
analyses, and projected effluent characteristics (as
described in information supplied by the industry). The
relevant values are listed below:
Pollutant Concentration
Parameter ^ 1203/1J
1SS 25
Cd 0.5
Pb o.S.
Hg 0.005
Zn 5
These concentration values were basically taken from a
composite analysis of the data contained in Table 17 and
Figures 6 through 9. Data on arsenic for the primary lead
industry is inconclusive.
The combination of neutralization and clarification is
required to achieve the best practicable technology
currently available. Clarification alone will reduce only
total suspended solids; neutralization without clarification
will reduce dissolved metals, but not suspended ones, and
will not provide an effluent of satisfactory quality.
Neutralization with lime to a pH in the 8 to 10 range will
reduce the concentrations of those metals precipitable as
hydroxides, and with properly designed retention facilities
will also reduce total suspended solids to below effluent
limitations guidelines. Use of lime has the further advan-
106
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tage that it, unlike sodium-based alkalies, forms a
relatively insoluble sulfate, CaSOU, which will tend to also
reduce the concentrations of dissolved sulfate in the
effluent. Neutralization will not significantly reduce
concentrations of those parameters which are soluble at an
alkaline pH.
Other considerations bearing on this recommendation include:
(1) The selected lime and settle technology has been
shown to be capable of achieving significant re-
ductions in the discharge of pollutants.
(2) The technology is compatible with industry
variations, including: age and size of plant,
processes employed, raw material variations, and
nonwater quality environmental impact.
(3) The technology, as an end-of-pipe treatment, can be
an add-on to existing plants, and need not affect
existing internal process and equipment
arrangements.
(>4) The effluent reduction benefits balance the costs
of the technology. On the basis of the information
contained in Section VIII, it is concluded that
those two plants not presently achieving the
recommended best practicable limitations would
require an estimated total maximum capital
investment of about $1,275,000 and an increased
operating cost of about $570,700/year to achieve
these limitations.
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SECTION X
BEST AVAILABLE TECHNOLOGY ECONOMICALLY ACHIEVABLE—
EFFLUENT LIMITATIONS GUIDELINES
The best available technology economically achievable is
identical to the best practicable control technology
currently available. The corresponding effluent limitations
are identical to those effluent limitations established from
usage of the best practicable control technology currently
available.
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SECTION XI
NEW SOURCE PERFORMANCE STANDARDS
The best available demonstrated control technology,
processes, operating methods, or other alternatives are
identical to the best practicable control technology
currently available. The corresponding standard of
performance is identical to the effluent limitations
guidelines established from the usage of the best
practicable control technology currently available.
Ill
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SECTION XII
ACKNOWLEDGMENTS
This document was developed by the Environmental Protection
Agency. The original contractor's draft report, dated
December 1973 was prepared by Battelle Memorial Institute,
Columbus, Ohio, under contract no. 68-01-1518. Mr. John B.
Hallowell prepared this original (contractor's) draft
report.
This study was conducted under the supervision and guidance
of Mr. George S. Thompson, Jr., Project Officer.
Preparation, organizing, editing, and final rewriting of
this report were accomplished by Mr. Thompson.
The following members of the EPA working group/steering
committee provided detailed review, advice and assistance:
W.J. Hunt, Chairman Effluent Guidelines Division
G.S. Thompson, Jr., Effluent Guidelines Division
Project Officer
S. Davis Office of Planning and Evaluation
D. Fink Office of Planning and Evaluation
J. Ciancia National Environmental Research
Center, Edison
T. Powers National Field Investigation Center,
Cincinnati
Excellent guidance and assistance was provided to the
Project Officer by his associates in the Effluent Guidelines
Division, particularly Messrs. Allen Cywin, Director,
Effluent Guidelines Division, Ernst P. Hall, Deputy
Director, and Walter J. Hunt, Branch Chief.
The cooperation of individual primary lead companies, who
offered their plants for survey and contributed pertinent
data, is greatly appreciated. These include:
American Smelting and Refining Company
Missouri Lead operating Company
Bunker Hill Company
St. Joe Minerals Corporation
The cooperation of the Water Pollution Control Subcommittee
of the American Mining Congress is also appreciated.
The following state and national EPA officials provided
considerable assistance: Mr. Thomas Jones, Missouri; Dr. Lee
113
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W. Stokes, Idaho; Mr. Mark Hopper, Region X, Seattle; Mr.
Donald G. Willems, Montana; Mr. Dick Montgomery, Region
VIII, Denver; Mr. Donald Benson, Nebraska; Mr. John B.
Latchford, Jr., Texas; Ms. Linda Nyatt, Texas; and Mr. Frank
Rozich, Colorado.
Acknowledgment and appreciation is also given to Ms. Kay
Starr, Ms. Nancy Zrubek, and Ms. Alice Thompson of the
Effluent Guidelines Division secretarial staff.
114
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SECTION XIII
REFERENCES
Brobst, D.A., and Pratt, W.P., editors, United
States Mineral Resources, Geological Survey
Professional Paper, United States Government
Printing Office, Washington, D.C., 1973.
Bureau of Mines, Minerals Yearbook, 1971, "Volume
I, Metals, Minerals, and Fuels", United States
Department of the Interior, Bureau of Mines, U.S.
Government Printing Office, Washington, D.C.
(1973).
Bureau of Mines, "Mineral Facts and Problems, 1970
Edition", Bureau of Mines Bulletin 650, U.S.
Department of the Interior, Bureau of Mines, U.S.
Government Printing Office, Washington, D.C.
(1970) .
Cotterill, C.H., and Cigan, J.M. (editors), AIME
World Symposium of Mining and Metallurgy of Lead
and Zinc, "Volume II, Extractive Metallurgy of Lead
and Zinc", The American Institute of Mining,
Metallurgical, and Petroleum Engineers Inc., Port
City Press, Baltimore, Maryland (1970).
1970 E/MJ International Directory of Mining and
Mineral Processing Operations, Published by Mining
Informational Services, Engineering and Mining
Journal, McGraw-Hill, New York (1970).
1973 Annual Book of ASTM Standards, Part 7,
Nonferrous Metals and Alloys, "Standard
Specification for Lead", B29-55 (Reapproved 1971).
Pourbaix, M., "Atlas of Electrochemical Equilibria
in Aqueous Solutions", (1966), English Translation,
Pergamon Press, 644 pp.
Hartinger, L.; "Waste Water Purification in the
Metalworking Industries, Precipitation of Heavy
Metals", Part 1, Problems, Bander Bleche Rohre
Dusseldorf, October, 1963, pp 535-540.
115
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SECTION XIV
GLOSSARY
Act
The Federal Water Pollution Control Act Amendments of 1972.
Acid Plant (Metallurgical)^
In primary lead smelting operations, a plant adjoining a
smelter which utilizes SO2 gases from the sintering
operation to produce sulfuric acid.
Baghouse
An air cleaning system consisting of multiple bag filters.
Achievable
Level of technology applicable to effluent limitations to be
achieved by July 1, 1983f for industrial discharges to
surface waters as defined by Section 301(b)(2) (A) of the
Act.
Best Practicable Control TechnologY_Currentlv._Rva,i 1 able
Level of technology applicable to effluent limitations to be
achieved by July 1, 1977, for industrial discharges to
surface water as defined by Section 301(B) (1) (A) of the Act.
Blast Furnace
In the primary lead industry, a shaft reducing furnace,
usually of rectangular cross section, in which concentrates
are mixed with fuel and fluxes and charged from the top so
that, as they descend to a level where an air blast is
admitted (through nozzles called tuyeres), melting takes
place under reducing conditions to form reduced metal and a
supernatant slag, which may be tapped continuously or
intermittantly.
Calcination
Heating of a solid to a temperature below its melting point
to bring about a state of thermal decomposition or phase
transition other than melting.
117
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Capital^ Costs
Financial charges which are computed as cost of capital
times the capital expenditures for pollution control. Cost
of capital is based upon the average of the separate costs
of debt and equity.
Category^and Subcategory
Divisions of a particular industry which possess different
traits that affect waste water treatability and require
different effluent limitations.
Cooling_Tgwer
A device in which hot water is pumped to the top of a tower
and cooled by allowing it to flow downward in thin streams
from one container to another.
Concentrates
The product of milling operations in which the ore values,
usually after grinding and milling, are separated and
concentrated.
Desilverizing
Removal of silver from lead bullion during the refining
operation.
Dewatering Classifier^Isometimes referred
to as a dewatering bin or tank)
A settling tank for clarifying process water; the tank may
have a continuously operating rake at the bottom, which
moves the settled solids or sludge towards an outlet pipe in
the bottom.
Prossing
Usually the first step in refining, the purpose of which is
to remove copper. Separation is effected by lowering the
temperature of the bullion in the kettle to a point where
copper comes out of metallic solution. Excess copper is
rejected from the melt and forms a crust or "head" on its
surface.
Effluent
The waste water discharged from a point source.
118
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Electrostatic Precipitator
An air cleaning system in which dust particles are
electrically charged and then collected on plates of the
opposite electrical charge.
Final Refining
Final refinery operation in which the last traces of zinc,
antimony, and arsenic remaining in the bullion are removed
by treatment with caustic soda, sometimes augmented with
additions of sodium nitrate.
Flux
A substance added to a smelting furnace charge that promotes
fusing of minerals or metals, or prevents the formation of
oxides.
Gangue
A waste rock or slag material remaining after most of the
metal values have been removed.
Gravity Concentration
Separation of ground ore into gangue and metal values by
virtue of difference in the density of the minerals in their
make-up, it can also be used to separate one ore mineral
from another if the differences in their specific gravity is
sufficiently large.
Flotation
A method of mineral separation in which a froth created in
water by air bubbles and a variety of reagents selectively
float some minerals (in a finely divided condition) by means
of adherence to oil-firm bubbles, while other minerals are
not so wetted and sink.
Harris Process
An alternative method for softening lead. Arsenic,
antimony, and tin are oxidized by adding sodium nitrate and
lead oxide, and the oxides formed are caused to react with
sodium hydroxide and chloride to form arsenates,
antimonates, and stannates.
119
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Indirect Cooling
Water cooling in which water is not in contact with any
material in process; jacket cooling of the blast furnace,
slag fuming furnace, kettles, and the underside of casting
molds are examples.
Jig
A device which separates crushed ore into values and gangue
by means of their differences in specific gravity in a water
medium. In some cases, it is used to separate one ore
mineral of value from another.
Lead Bullion (sometimes referred to as bullion)
The metallic product of the lead hearth or blast furnace;
normally it contains quantities of copper, arsenic antimony,
or bismuth, which must be removed in the_refining operations
to produce lead of acceptable specifications.
Lime Sump
A pit or tank to which lime is added to precipitate out
dissolved metallic impurities from the lead smelter waste
water.
Matte
A metallic sulfide mixture produced in the smelting of
sulfide ores.
New Source Performance
Level of technology applicable to effluent limitations as
outlined in Section 306 of the Act, which provides for the
control of the discharge of pollutants and reflects the
greatest degree of effluent reduction 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.
Ore
A natural mineral from which materials such as metals can be
economically extracted.
Parkes Process
A process for removing silver and gold from lead bullion;
zinc is added to the bullion in a refining kettle, where it
120
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combines with silver and gold to form compounds that are
virtually insoluble in lead and, being much lighter,
accumulate on the surface where they can be skimmed off.
EH
The logarithm, to the base 10, of the reciprocal of the
concentration of hydrogen ions in an aqueous solution; it
denotes the degree of acidity or basicity of a solution. At
25 C, seven is the neutral value. Acidity increases with
decreasing values below seven. Basicity increases with
increasing values above seven.
Point Source
A single source of water discharged from an individual
plant.
Refining
In the primary lead industry, refining implies the removal
of impurities from blast furnace or hearth smelted lead
bullion, usually by a series of treatments in a succession
of large hemispherically shaped kettles.
Reyerberatgry Furnace
A furnace in which the charge is melted on a shallow hearth
by a flame applied from one end and passes upward over the
charge, which heats a low roof, shaped to reflect the flame
and radiate heat onto the charge.
Settling Pond
A pond, natural or artificial, used for settling out solids
by gravity from waste water effluents.
Sinter
The product of the sintering machine; agglomerated masses of
relatively sulfur-free concentrates of suitable size for
blast furnace feed in which some of the impurities such as
arsenic and cadmium have been removed, at least partially,
by volatilization.
Sintering
In primary lead smelting, a process for removing sulfur from
the concentrates by oxidation, and impurities, such as
arsenic and cadmium by volatilization, and at the same time
121
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fritting the concentrates together into manageably sized
masses suitable for charging into the blast furnace.
Sintering Machine
A horizontal sintering furnace containing traveling,
articulated grates which move the feed continuously in
conveyer belt fashion under controlled conditions of
combustion to produce a nearly sulfur-free sinter of a size
suitable for furnace charging.
Skimmings
Wastes from melting operations that are removed from the
surface molten metal; the wastes consist of metal that is
contained in oxidized metal.
The fused agglomerate of oxides or salts, which separates in
metal smelting and floats on the surface of the molten
metal. It is formed by the combination of gangue of the
ore, ash of the fuel, fluxes and, in some cases, the furnace
lining. The slag is often the medium by means of which
impurities may be separated from metal.
Slaa_Fumin2_Furnace
A furnace used to recover zinc from lead smelter blast
furnace slag; zinc is separated from the slag by
volatilization.
Slag Granulation
In the primary lead industry, the granulation of slag is
produced by contact, as it flows from a furnace, with jets
of high pressure water.
Smelting
In the primary lead industry, smelting implies a reduction
of the lead oxide in the ore to produce elemental lead
(bullion). Fluxes in the form of limestone and silica unite
with the gangue of the concentrate and ash of the fuel to
form a liquid slag which collects some of the impurities.
Softening
A refining step is performed usually after dressing to
remove antimony, arsenic, and any tin that is present in the
122
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lead bullion. These impurities harden the lead, and their
removal renders it softer; hence, the term softening. There
are two principal methods of softening, air-oxidation of the
molten bullion in a reverberatory furnace or the Harris
process.
Speiss
A mixture of arsenides and antimonides produced in the
smelting of arsenical and antimonial ores.
Standard_of_Perfgrmance
A maximum weight discharged per unit of production for each
constituent that is subject to limitations. The weight is
applicable to new sources as opposed to existing sources,
which are subject to effluent limitations.
Thickener
In primary lead smelters, a vessel or apparatus for
separating waste solids from waste water.
Tuyere
A nozzle through which an air blast is delivered to a cupola
or a blast furnace.
Venturi Air Scrubbers
An air cleaning system consisting of intense water-spray
cleaning of the air at a point where the air goes through a
restriction (venturi) in the duct.
Waste Water Constituents
Materials which are carried by or dissolved in a water
stream for disposal.
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TABLE 21
CONVERSION TABLE
MULTIPLY (ENGLISH UNITS) by TO OBTAIN (METRIC UNITS)
ENGLISH UNIT ABBREVIATION CONVERSION ABBREVIATION METRIC UNIT
acre
acre - feet
British Thermal
Unit
British Thermal
Unit/pound
cubic feet/minute
cubic feet/second
cubic feet
cubic feet
cubic inches
degree Fahrenheit
feet
gallon
gallon/minute
horsepower
inches
inches of mercury
pounds
million gallons/day
mile
pound/square
inch (gauge)
square feet
square inches
ton (short)
yard
* Actual conversion, not a multiplier
ac
ac ft
BTU
BTU/lb
cfm
cfs
cu ft
cu ft
cu in
%e
ft
gal
gpm
hp
in
in Hg
Ib
mgd
mi
psig
sq ft
sq in
ton
yd
0.405
1233.5
0.252
0.555
0.028
1.7
0.028
28.32
16.39
0.555PsF-32)*
0.3048
3.785
0.0631
0.7457
2.54
0.03342
0.454
3,785
1.609
(0.06805 psig +1)*
0.0929
6.452
0.907
0.9144
ha
cu m
kg cal
kg cal/kg
cu m/min
cu m/min
cu m
1
cu cm
*C
m
1
I/sec
kw
cm
atm
kg
cu m/day
km
atm
sq m
sq cm
kkg
m
hectares
cubic meters
kilogram - calories
kilogram calories/kilogram
cubic meters/Mnute
cubic meters/minute
cubic meters
liters
cubic centimeters
degree Centigrade
meters
liters
liters/second
killowatts
centimeters
atmospheres
kilograms
cubic meters/day
kilometer
atmospheres (absolute)
square meters
square centimeters
metric ton (1000 kilograms)
meter
124
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Region V8 Library
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