UNfTED STATES ENVIRONMENTAL PROTECTION AGENCY
WASHINGTON, D.C 20460
OFFICE OF
SOLIO WASTE AMD EMERGENCV FIESPC
MEMORANDUM
SUBJECT: Report on "
FKOM: /ruett "^DeGeTfe, Chief
Special Wastes Branch
amation of Aluminum Finishing Sludges"
TO:
Jim Lounsbury, Special Assistant
Waste Management Division
Attached fot your use is the subject report. Our review
indicates that the waste sludges are not of direct concern
to the Branch as a possible exempt waste under the Bevill
amendment or other special exemption. However, you may find
this report relevant to your work on the waste minimization
program.
Attachment
cc: Joe Carra
Bob Delli nger
Francis Mayo (WERL-Cincinnati)
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PROJECT SUMMARY
RECLAMATION OF ALUMINUM FINISHING SLUDGES
BY
F. Michael Saunders
School Of Civil Engineering
Georgia Tech Research Corporation
Georgia Institute Of Technology
Atlanta, Georgia 30332
CR110290-01-0
Project Officer
Thomas J. Powers
Industrial Wastes and Toxic Technology Division
Water Engineering Research Laboratory
Cincinnati, Ohio 45268
WATER ENGINEERING RESEARCH LABORATORY
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
CINCINNATI, OHIO 45?68
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UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
OFFICE OF RESEARCH AND DEVELOPMENT
WATER ENGINEERING RESEARCH LABORATORY
CINCINNATI. OHIO 45268
DATE: November 5, 1987
SUBJECT: Awareness Memo: Final Report
"Reclamation of Aluminum Finishing Sludges"
F. Michael Saunders, Georgia Tech Research Corporation
FROM: Francis T. Mayo, Director
Water Engineering Research Laboratory
TO: Truett Degeare
Office of Solid Waste
The subject final report is forwarded to your office as an example of a
long term research effort on sludge treatment potential for reclamation. This
report illustrates the commercial feasibility of reclamation of aluminum
finishing sludges as commercial products. Results are presented for enhanced
dewatering of these industrial sludges and the acidic extraction of aluminum
from them. Project results indicate that sludge reclamation can be achieved,
producing a commercially marketable product and eliminating a solid waste
disposal problem for the industry.
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PROJECT SUMMARY
RECLAMATION OF ALLUMINUM FINISHING SLUDGES
F. MICHAEL SAUNDERS
ABSTRACT
The reclamation of aluminum-anodizing sludges produced as a result of
finishing extruded architectural aluminum using etching and anodizing
processes was studied by Georgia Tech Research Corporation. Two sequential
phases focused on (1) enhanced dewatering of aluminum-anodizing sludges with
recessed-chamber filter presses and (2) acidic extraction of de watered
aluminum-anodizing sludges to produce commercial-strength solutions of
anmixjumsuVfa.te', i.e., liquid alum.
A high-pressure (14 to 15 bar) and a diaphragm filter press were effective
in dewatering aluminum anodizing sludges to cake solids contents of 27% to 29%
and 25% to 31%, respectively. These values were well above the 21% value
required to justify pursuit of direct acidic extraction of aluminum.
Commercial-strength solutions of aluminum sulfate with concentrations of 8% as
Al?0- were produced using conventional-neutralization, segregated-
neutralization, etch-recovery sludge cakes. The trace metal contents of the
T1
alum products were, in general, typical of commercial products.',',
.=*»
This Project Summary was developed by EPA's Water Engineering Research
Laboratory, Cincinnati, OH, to announce key findings of the research project
that is fully documented in a separate report of the same title (see Project
Report ordering information at back).
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INTRODUCTION
Aluminum anodizing plants may produce up to 500 metric tons/month of
finished architectural aluminum extrusions. In the finishing process,
approximately 3% to 5% of the mass of the extrusions is discharged as soluble
aluminum metal to plant wastewaters. These aluminum-bearing wastewaters are
typically neutralized, resulting in the production of a highly gelatinous,
aluminum-hydroxide suspension. When these suspensions are thickened and
dewatered, the remaining wet residue can equal or exceed the mass of finished
aluminum extrusions produced at a plant. This solid waste residue must then
be disposed of in a landfill or by other acceptable methods. Solid waste
reduction, therefore, has an extremely high priority in this industry and can
be addressed through alterations in aluminum-finishing and waste-treatment
procedures or by reclamation of the aluminum value in the dewatered solid
waste residue.
A major deterrent to the reclamation of the aluminum value in
aluminum-anodizing sludges is the high levels of moisture associated with
dewatered sludge cakes. Moisture generally constitutes more than 80% of the
total mass of dewatered sludges, thereby increasing sludge hauling and
ultimate disposal costs and contributing to the dilution of the aluminum
value. The high moisture content is attributable to the gelatinous,
hydrophilic nature of the aluminum hydroxide precipitate formed during
conventional neutralization of aluminum-anodizing wastewaters. To investigate
the extent to which sludge moisture content could be reduced, recessed-chamber
filter presses were selected for mechanical dewatering studies because of the
high pressure differentials (e.g., 6 to 15 bar) typically achieved with these
systems and their ability to produce dewatered sludge cakes with the lowest
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moisture content achievable by conventional mechanical dewatering systems.
The production of liquid alum from aluminum-anodizing sludges can be
represented by the addition of sulfuric acid (H^SO.) to an
aluminum-anodizing sludge containing dry fixed solids, represented by
A1(OH)3, and moisture. In an equation format, the acidic extraction of
aluminum is represented by:
2A1(OH>3 + xH20 + 3H2S04 ---- A12(S04)3 + (6 + x)
To produce a commercial -strength solution of liquid alum containing 26.8%
AlpfSO.K (i.e., 8% as Al^O.,), the aluminum-hydroxide content of a
sludge would have to be equal to 16% on a fixed solids basis. This value is
indicative of a total dry (103°C) solids content of approximately 21% for a
dewatered sludge cake. This is an exceptionally high value that, when
compared to current practice, is not routinely achieved. Therefore, effective
dewatering of sludge solids was a critical step in establishing the potential
for reclamation of aluminum-anodizing sludges. Without the ability to produce
a dewatered sludge cake with a solids content of 21%, further
consideration of direct reclamation of the aluminum value of
aluminum-anodizing sludge was futile.
Previous studies have been conducted in the laboratory to establish the
feasibility of producing liquid alum from aluminum-anodizing sludges. The
purpose of this study was to conduct extractions with three types of
aluminum-anodizing wastes, to establish the kinetics of the acidic extraction,
and to evaluate the quality of the products produced.
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PROCEDURES
Two recessed-chamber, fixed-volume filter presses (i.e., 470 mm and 250
mm) were employed in the study to establish the extent to which
aluminum-anodizing sludges could be dewatered. Low- and high-pressure
filtration studies were conducted with the presses, and the larger press was
operated with variable-volume diaphragm plates. Constant operational pressure
ranges of 6 to 7 bar (87 to 102 psi) and 14 to 15 bar (203 to 218 psi) were
employed throughout the studies and are typical, respectively, of low- and
high-pressure systems marketed for waste treatment practice.
Pressure filtration studies were conducted at the site of an
aluminum-anodizing facility producing architectural aluminum extrusions.
Aluminum finishing processes included alkaline cleaning, caustic etching,
acidic desmut, conventional and two-step sulfuric-acid anodizing, and
hot-water sealing. Wastewater treatment included neutralization with spent
acid and virgin caustic; polymer flocculation; gravity sedimentation; rotary
vacuum filtration of thickened sludge; and recycle of clarified water into
finishing rinses. Samples of the underflow suspension from the clarifier were
collected from the influent line to the rotary vacuum filter and were examined
intensively on the filter presses. These sludge suspensions were identified
as conventional neutralization (CN) suspensions. A CN suspension from a
similar aluminum-anodizing plant was also examined.
One other type of suspension was examined during the pressure filtration
studies. Suspensions formed by batch neutralization of spent caustic etch
from the aluminum-finishing line with spent anodizing acid were identified as
segregated neutralization (SN) suspensions. These suspensions were not
produced in the plant treatment systems, but were produced experimentally in
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0.2-m3 ( 50-gal) volumes for use In the filtration and acidic extraction
portions of the study. These suspensions were formed by pumping anodizing
acid into an intensively mixed, lined reactor containing spent caustic etch
until a pH of 9 to 10 was achieved. These suspensions were then blended with
CN suspensions or used directly in pressure filtration studies.
Acidic extraction of aluminum-anodizing sludges was conducted in a
laboratory-scale reactor equipped with a mixer and temperature control system
used to maintain post-acid-addition temperatures at 50°C to 90°C.
Following addition of acid, samples were collected at 30- to 60-roin intervals
to monitor the progress of the reaction. A detailed material balance was
conducted on total reaction mass and on the mass of aluminum in each reactor.
Three types of suspensions were examined. The CN and SN suspensions as
included in filter-press dewatering studies were examined. In addition, an
etch recovery (ER) sludge provided by an aluminum-anodizing plant was
examined. This residue was produced from a patented system designed to remove
aluminum from caustic etching suspensions allowing for the continuous recovery
and reuse of the caustic etch suspension. The aluminum is crystallized as an
aluminum hydrate (e.g., A12°3 '* H2Q* at temPeratures of 55°c to
65°C, removed from the caustic etch, and water washed using, for example, a
vacuum filtration system. The dewatared residue was provided as one sample in
0.2-m volume and had a solids content of 91.6% and an aluminum content of
43.6 g/100 g fixed solids.
FILTER PRESS DEWATERING
Typical characteristics of the suspensions obtained from or experimentally
produced at two aluminum-anodizing plants and examined during the filter press
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studies are included in Table 1. The two clarlfier underflow suspensions, the
primary focus of the dewatering studies, were slightly alkaline and relatively
dilute. The specific resistance values for all suspensions were similar,
although that for the SN suspension was the lowest, indicating slightly
improved dewatering characteristics. Although not directly indicative of
final cake solids content for a mechanical dewatering system, the dewatered
cake solids concentration (Ck) determined as a part of the specific
resistance test is effective in indicating the relative potentioal to which a
suspension can be dewatered. The clarifier underflow from plant X had the
lowest Ck value and was approximately 50% to 60% of that for the
neutralization basin effluent and clarifier underflow from plant A.
Furthermore, the solids content values for all CN suspensions ranged from 7%
TABLE 1. TYPICAL CHARACTERISTICS OF ALUMINUM-ANODIZIMQ SUSPENSIONS FROM
PARTICIPATING PLANTS
PH
Plant A
Neutralization basin
effluent 8.2
Clarifier underflow 8.2
Segregated neutralization* 9.6
Plant C
Clarifier underflow 7.6
Suspended
Solids
SS,
9/L
2.4
41
143
21
Specific
Resistance
Tm/kg+
3
4
1.4
3
Ck.
12
13
47
7
Capillary
Suction Time
Seconds
60
150
530
66
plant waste flow.
-Tin/kg = 1012 meters/kg
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to 13%, well below the minimum desired value of 21%, indicating indirectly the
nature of the problem with respect to aluminum recovery as liquid alum. SN
suspensions produced experimentally had exceptionally high suspended solids
concentrations and the lowest and highest values for specific resistance and
specific-resistance cake solids (Ck), respectively. This indicated the high
potential for use of SN suspensions in the production of liquid alum.
High-pressure and low-pressure filtration studies were conducted at
constant feed pressures of 6 to 7 bar (87 to 102 psi) and 14 to 15 bar (203 to
218 psi) using two pilot-scale filter presses. Replicate runs were usually
performed for an individual suspension at each feed pressure with each
replicate run being conducted for a variable time of filtration. For example,
a CN suspension from plant A was examined in one series of runs at two
concentrations and three filtration time intervals for each operational
pressure, as indicated in Table 2. Filtrate volume data were also collected
as a function of time, as presented in Figure 1 for runs 24 through 29. The
runs were highly reproducible with respect to filtrate volume. This allowed
for evaluation of the effect of filtration time on dewatered cake solids,
evaluation of the ultimate filtrate volume that could be produced at infinite
filtration time, and, thereby, the ultimate dewatered-cake solids
concentration, (Ck)ULT. Using a procedure developed in conjunction with
this study, the ultimate filtrate volume was established using a procedure
illustrated in Figure 2. With the projected ultimate filtrate volume (i.e.,
filtrate volume at a projected filtration rate of zero), both the ultimate
cake solids concentration, (OUL j, and the cake solids concentration at
the point of collection of 90% of the ultimate filtrate volume, (Ck)Q g,
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were calculated. This is illustrated in Table 3 for all low-pressure and
high-pressure runs with CN suspensions
TABLE 2 RESULTS FOR FILTER PRESS DEWATERING OF CN SUSPENSIONS (PLANT A, RUNS
24-29)
Influent Suspension
Specific
Suspended Resistance
Runs Solids, r, Cfc,
g/L Tm/kg* %
24,25,26 73 3.6 15.4
27,28,29 37 2.6 14.7
Filtration
Pressure,
bar
14-15
14-15
Time of
Filtration,
min
75,50,35
156,90,68
Cake
Solids,
28.1,26.4,25.
28.9,25.1,23.
3
6
*Tm/Kg = 1012 meters/Kg
TABLE 3. PREDICTED CAKE SOLIDS CONCENTRATIONS FOR FILTER-PRESS DEWATERING OF
_ CN SUSPENSIONS FROM PLANT A _ _ _
Predicated Cake Solids Concentration
Range of Suspended (C^JuLT (Ck)o.9
Solids
g/L _ % _ %_
High pressure (14 to 15 bar)
21-73*
Low pressures (6 to 7 bar)
17-61 +
27-29
22-25
25-26
21-23
*Results for a total of 15 runs
Results for a total of 13 runs
from plant A. The ultimate cake solids concentrations, (C^L-p for both
low- and high-pressure filtration were at or above the desired value of 21*,
as were all (Ck)Q g values, indicating that it was feasible to explore the
acidic extraction of sludge aluminum. Data collected for a similar CN sludge
from plant X indicated that high- and low-pressure filtration produced
(Ck)ULT values of 24.5% and 17.6%, respectively, indicating that only
high-pressure filtration would be acceptable. Therefore, in general, CN
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sludges can be dewatered to solids concentrations ranging from 18% to 29%
using filter-press systems. Furthermore, high-pressure systems appear most
suitable for production of dewatered sludge cakes that are suitable for direct
production of liquid alum.
SN suspensions, produced by direct neutralization of spent caustic etch
suspensions (containing elevated concentrations of aluminum, e.g., 50 to 150
g/L) with spent desmut or anodizing acids, have better dewatering properties
than CN suspensions, as shown in Table 1. Samples of these experimentally
produced suspensions were blended with CN suspensions, since both would be
produced at a plant employing SN, to determine the impact on dewatering. Data
in Table 4 indicate a dramatic impact of SN solids on ultimate solids
concentration, as well as the high level of cake solids concentration, i.e.,
51%, that can be achieved with SN suspensions alone.
TABLE 4. PREDICTED CAKE SOLIDS CONCENTRATION FOR HIGH-PRESSURE FILTER-PRESS
DEWATERING OF BLENDS OF SN AND CN SUSPENSIONS
Predicted Cake Solids
SN Suspension in Blend
of SN-1 and CN-2 Suspensions,
% (by volume)
0
5
15
30
100
Suspended
Solids,
9/L
38
47
60
78
180
Concentration
WULT,
%
29
33
37
39
51
%
27
31
34
37
49
The use of variable-volume, or diaphragm, plates was examined on the
470-mm press using a low-pressure (6 to 7 bar) addition of a suspension to the
press followed by a high-pressure (15.5 bar) squeeze cycle, in which the
contents of each chamber were compressed until no filtrate was released.
Examples of the filtrate volume collected with time during the fill (or
filter) and squeeze portions of several replicate runs are presented in Figure
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3. Following filtration with the diaphragm plates, the CH suspensions from
plant A had final cake solids concentrations that ranged from 25% to 31% and
averaged 29%. These values were equivalent to or slightly higher than the
analogous (C^MIT values obtained for high pressure filtration (see Table
3). The limited increase in cake solids concentration would not appear to
warrant the use of diaphragm plates, although a comparison of capital and
operating costs may dictate otherwise.
ACIDIC EXTRACTION OF SLUDGES
Extractions were conducted on numerous aluminum anodizing sludges,
following dewatering by pressure filtration, and on blends of dewatered
sludges. Each extraction was initiated by addition of a fixed mass of
sulfuric acid to a known mass of dewatered sludge. A temperature control
system was used to maintain a prescribed control temperature. The
temperature, however, was not controlled during the initial acid addition
phase but was controlled at temperatures of 50°C to 90°C following
dissipation of heat associated with the initial exothermic reaction.
The characteristics of the sludges extracted are summarized in Table 5.
The aluminum content of the sludges, expressed on a mass basis in terms of the
fixed (550°C) solids, varied from 31% to 43.6%, comparing favorably with the
AKOH), form, with,a theoretical aluminum content of 34.6%, used in Equation
1 to describe the chemistry of the acidic extraction. Sulfuric acid was added
to dewatered cakes, in accordance with Equation 1, at the rate of 1.89 g
H2S04/g fixed solids or 5.44 g H2S04/g Al. Acid doses were also
expressed as a percentage of the stoichiometric acid dose based on sludge
10
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TABLE 5. CHARACTERISTCS OF ALUMINUM-ANODIZING SLUDGE CAKES USED IN ACIDIC
EXTRACTION STUDIES
Cake Solids Aluminum
Sludge Cake Total, Fixed, Content,
% % g/1 OOg fixed sol ids
Conventional Neutralization
CN-1
CN-2
Segregated Neutralization
SN-1
Etch Recovery
ER-1
Blended Cakes
CN-2 & SN-1
CN-2 & ER-1
18.1
17.4
36.8
91.6
25.2
30.2
13.3
13.9
29.9
66.4
21.4
22.5
35.6
39.2
31.0
43.6
34.6
41.3
aluminum content (e.g., the addition of 5.44 g H-SO./g Al to a sludge cake
would represent a stoichiometric dose of 100%).
Filtrate aluminum data in Figure 4 indicate the results of a typical
acidic extraction. In general, within an initial 1-hr period, the aluminum
contained in the sludge cakes was extracted to near completion and approached
the concentration of commercial-strength liquid alum (i.e., 8% as Al^Oo).
Because of the robust exothermic nature of the reaction during the initial
period, the controlled reaction temperature had only a minimal effect on the
rate of the reaction, as measured after a 0.5-hr extraction period.
Data in Table 6 indicate that 89% to 109% of the aluminum placed in the
reactors was accounted for in the studies conducted. In addition,the data
indicate that, for all but the ER cakes, 93% to 100% of the aluminum was
extracted and appeared in the soluble form as aluminum sulfate. Those
instances in which the percentage extracted was low (i.e., 93%) were
attributable to extractions in which acid addition v/as less than the
stoichiometric amount.
11
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TABLE 6. MATERIAL BALANCE ON ALUMINUM AND ALUM PRODUCT QUALITY FOR ACIDIC
EXTRACTION OF SLUDGE CAKES
Sludge Cake
Conventional Neutralization
CN-1
CN-2
Segregated Neutralization
SN-1
Etch Recovery
ER-1
Blends
CN-2 & SN-1
CN-2 & ER-1
Reactor
Material
Balance-
Aluminum,
% Al
recovered
104
99
100-105
89-1 09
99
102
Alum Product
Al extracted
into soluble
form,
% of total Al
93-97
97
99-1 00
69-85
99
82
Concentration
% as A1?03
7.4-8.0
8.1-8.8
8.1-9.0
8.3-9.2
8.2
8.8
For ER cakes, the level of aluminum extracted ranged from 69% to 85%. In
some extractions of these cakes, dilution water (reauired because of the high
solids content of these sludges) was withheld until later portions of the
extraction. This produced an elevated acid strength in the initial extraction
phase, and a higher level of aluminum extraction (i.e., 81% to 85%), as
compared to those in which the additional water was added prior to acid
addition and lower portions were extracted (i.e., 68% to 69%).
The trace metal content of liquid alum produced with CN-2, SN-1, and ER-1
sludge cakes compared favorably with commercial products. Data in Table 7
indicated that concentrations of cadmium, chromium, iron, silver, and zinc in
alum produced from aluminum-anodizing cakes compared favorably with those
contained in commercial alum products obtained from, and used at, two large
municipal water treatment plants. The concentrations of lead were moderately
12
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higher than those in the commercial products.
TABLE 7. METAL CONTENT OF LIQUID-ALUM SAMPLES, PRODUCED FROM CN-2, SN-1, AND
ER-1 SLUDGE CAKES, AND TWO COMMERCIAL ALUM PRODUCTS
Metal
Concentration, mg/L
Sludge-Cake Alum
Cadmium, Cd
Chromium, Cr
Iron, Fe
Lead, Pb
Nickel, Ni
Silver, Ag
Tin, Sn
Zinc, An
CN-2
0.4
30.0
60.0
20
752
0.7
914
12
SN-1
0.3
4.4
18.3
19
8
0.2
28
6
ER-T
0.3
3.7
21.0
26
7
0.08
17
7
Commercial Alum
Plant 1
0.03
78
1845
6.6
44
0.25
155
8.5
Plant 2
0.3
0.9
2080
4.1
44
0.2
--
8.5
Concentrations of nickel and tin in alum produced from a conventional
sludge (CN-2) were significantly higher than those in the commercial
products. This was attributed to the nickel and tin used in the two-step
anodizing process at the plant. Nickel and tin concentrations in the alum
produced from SN and ER cakes were well below the concentrations contained in
the commercial products. Therefore, with the exception of nickel and tin
originating from a two-step anodizing system, the levels of trace metals
contained in the alum produced from aluminum-anodizing sludges were similar to
those contained in commercial alum, indicating the potential utility of the
alum for use in coagulation of drinking waters. However, since less than 10%
of commercial alum is actually used in the treatment of drinking water, it is
apparent that the alum products produced from aluminum-anodizing sludges can
be marketed for non-potable-water uses in industry.
CONCLUSIONS
Research was conducted on filter-press dewatering followed by reclamation
of three types of aluminum-anodizing sludges as commercial-strength liquid
alum. Numerous conclusions were drawn from the study.
13
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Pressure filtration studies were conducted with two pilot-scale,
fixed-volume, recessed-chamber filter presses at low (5 to 7 bar) and high (14
to 15 bar) pressures. The solids content of dewatered sludge cakes at the
ultimate completion of a filter press run were projected from filtration rate
data. CN suspensions had ultimate cake solids contents of 22% to 25% and 27%
to 29%, respectively, at low (6 to 7 bar) and high (14 to 15 bar) pressures
for suspensions with suspended solids concentrations of 17 to 73 g/L.
SN suspensions could be effectively dewatered separately and resulted in
major improvements in the dewatering of CN suspensions when blended with
them. At low and high pressures, ultimate cake solids contents of 49% and
51%, respectively, were achieved with SN suspensions. Blends of SN
suspensions at 5% to 30% volumetric ratios with CN suspensions resulted in
ultimate solids contents of 33% to 39% with high-pressure filtration and 31%
to 37% with low-pressure filtration.
A diaphragm press was used effectively to dewater aluminum anodizing
suspensions. CN suspensions had final cake solids contents of 25% to 31%,
while 5% to 30% volumetric blends of SN suspensions with CN suspensions had
solids contents of 31% to 43%.
Commercial-strength solutions of liquid alum can be effectively and
rapidly produced with the addition of sulfuric acid. Addition of stoichio-
metric quantities of acid, based on sludge aluminum content, resulted in
virtually complete extraction within 30 to 60 min.
CN sludge cakes with solids contents of 17% to 18% were extracted to
produce liquid alum with concentrations of 7.4% to 8.8% as AlgOj. A total
of 93% to 97% of the aluminum was extracted.
14
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SN sludge cakes with solids contents of 36.8% were extracted to produce
liquid alum with concentrations of 8.1% to 9.0% as AlpO.,. An ER sludge
with a solids content of 91.6% produced a liquid alum with a concentration of
8.3% to 9.2% as AKCq. Acid addition resulted in extraction of 69% to 85%
of the aluminum. Addition of SN or ER solids to CN solids increased the
aluminum content of the blended sludge and could be effectively extracted to
easily produce commercial-strength liquid alum.
The cadmium, chromium, and iron concentrations of liquid alum produced
from CN sludges were less than those of commercial alum products, while lead,
silver, and zinc concentrations were slightly above those for commercial alum
products. The concentrations of nickel and tin were sixfold to seventeenfold
higher than those in commercial alum. The high nickel and tin concentrations
were attributed to dragout from the two-step anodizing process and to the use
of nickel in seal tanks. Segregation of these wastes from plant wastewaters
may be needed to eliminate them from the sludges produced for extraction and
reclamation.
The full report was submitted in fulfillment of CR110290-01-0 by Georgia
Institute of Technology under the sponsorship of the U.S. Environmental
Protection Agency.
15
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F. Michael Saunders is with the School of Civil Engineering, Georgia Tech
Research Corporation, Georgia Institute of Technology, Atlanta, GA 30332.
Thomas J. Powers is the EPA Project Officer (see below)
The complete report, entitled "Reclamation of Aluminum Finishing Sludges"
(Order No. PB ; Cost: , subject to change), will be
available only from:
National Technical Information Service
5285 Port Royal Road
Springfield, VA 22161
Telephone: 703-487-A650
The EPA Project Officer can be contacted at:
Water Engineering Research Laboratory
U.S. Environmental Protection Agency
Cincinnati, Ohio 45268
16
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80 r
i-p r-p r-p rp r-p
~
Run Number
24
25
T 26
X 27
28
X 29
o1-1
0
i i i i i i i i i i i i i i i i i i i i * i i
40
80 120 160
Time, min.
200
240
Figure 1. Cumulative filtrate volume for high-pressure (14 to 15 bar)
dewatering of CN sludges.
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LJL.
0.00
0.000
0.050 0.100
Volume, m3/ h«J
0.150
0.200
Figure ?.. Filtration rate for high pressure dewatering of CN sludges and
projection of ultimate filtrate volume produced.
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ou
60
o)"40
E
D
o
>
20
i i i i | i i i i | i i i i | i r- i [
172 Filter
o Squeeze
175 Filter
Q Squeeze
T 176 Filter
A Squeeze
X 179 Filter
X Squeeze
-
^-r------^x'?SS!^H"A
, , , , I , , , , I , , , . I . . . I ' I
0 40 80
.
-
12i
Time, min.
Figure 3.
Cumulative filtrate volume for filter and squeeze portions of
diaphragm filter press dewatering of CN sludges.
-------
10 i-'
9,
8
rrvj J
10 z 4
oc:
I I I I
DEWATERED SLUDGE CAKE
STOICHIOMETRIC
RUN TEMP ACID DOSAGE
2-1 90 *C 100 x if
2-2 50 *C 100 5 -h
0
I
2
TIME, HR
8
Figure <1. Filtrate aluminum concentration for sulfuric add extraction of
sludge cake CM-?.
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