Development Document for Effluent Limitations Guidelines
   and New Source Performance Standards for the
BAUXITE REFINING SUBCATEGORY
 of the Aluminum Segment of the
Nonferrous Metals Manufacturing
   Point Source  Category
                            MARCH 1974
            U.S. ENVIRONMENTAL PROTECTION AGENCY
        *        Washington, D.C. 20460

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                   DEVELOPMENT DOCUMENT

                             for

              EFFLUENT LIMITATIONS GUIDELINES

                             and

             NEW SOURCE  PERFORMANCE STANDARDS


                           for the

                     BAUXITE REFINING
                         SUBCATEGORY
                           of the
                     ALUMINUM SEGMENT
                           of the
              NONFERROUS METALS MANUFACTURING
                   POINT SOURCE CATEGORY
                        Russell Train
                       Administrator
                       Roger  Strelow
Acting Assistant Administrator for Air and Water Programs
                        Allen  Cywin
          Director, Effluent Guidelines Division

                  George s. Thompson, Jr.
                      Project  Officer
                        March,  1974
               Effluent Guidelines Division
             Office of Air and Water Programs
           U.S.  Environmental  Protection Agency
                 Washington, D.c.    20U60
    For aale by the Superintendent of Document*, U.S. Government Printing Office, Washington, D.C.20402 - Prloe $1.46

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                            ABSTRACT

This document presents the findings of a  study  of  the  bauxite
refining  industry by the Environmental Protection Agency for the
purpose  of  developing  effluent   limitation   guidelines   and
standards  of performance for the industry, to implement Sections
304, 306, and 307 of the Federal Water Pollution Control  Act  as
amended.

Effluent  limitations guidelines contained herein for the bauxite
refining industry set forth  the  degree  of  effluent  reduction
attainable  through  the  application  of  the  best  practicable
control technology currently available, and  the  application  of
the best available technology economically achievable, which must
be  achieved  by existing point sources by July 1, 1977, and July
1, 1983, respectively.  The  standards  of  performance  for  new
sources  contained  herein  set  forth  the  degree  of  effluent
reduction  attainable  through  the  application  of   the   best
available  demonstrated  control technology, processes, operating
methods, or other alternatives.

The major process waste from bauxite  refining  is  the  red  mud
residue  remaining after extraction of the alumina.  Thousands of
tons per  day  are  produced  by  the  typical  refinery.   Total
impoundment  of  process  wastes  was determined to represent the
best  practicable  control  technology  currently  available  for
existing  point  sources.   No  discharge  of process waste water
pollutants to navigable waters is the effluent limitation  to  be
achieved  by  existing  point sources by July 1, 1977, and as the
standard of performance for new sources.

Supportive data and rationale for  development  of  the  effluent
limitations guidelines and standards of performance are contained
in this report.
                               111

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XI       NEW SOURCE PERFORMANCE STANDARDS




XII      ACKNOWLEDGMENTS




XIII     REFERENCES




XIV      GLOSSARY
87




89




91



93
                          VI

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                             FIGURES

Number

  1      Location of Alumina Refining Plants in the U.S.

  2      Generalized Diagram of the Bayer Process

  3      Generalized Diagram of the Combination Process

  4      Generalized Diagram of Water Circuit for Bayer
         Plant Employing Total Impoundment

  5      Flowsheet of Digestion and Heat-Recovery System

  6      Mean Annual Lake Evaporation in the United States

  7      Mud Lake Dike Construction

  8      Generalized Diagram of Basic Water Balance
         for a 3000 ton/day Bauxite Refinery Processing
         Jamaican Bauxite
10

16

17


19

26

29

56



71
                            Vll

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                            TABLES
 6

 7

 8

 9

10

11


12




13


1U

15

16


17
                                                     ESS®
Operating companies, Locations, capacities
and Date of Operation of U.S. Bauxite Refining Plants  8

Production of Primary Aluminum in the United
States                                                 11

Maximum Rainfalls                                      24

Rainfall and Evaporation Data                          28

Range of Composition of Bauxites for Alumina
Production                                             31

Characteristic Analyses for Various Bauxites           33

Red Mud Insoluble Solids                               38

Red Mud Slurry Soluble Solids                          39

Screen Analysis of Red Mud                             39

Range of Chemical Analyses of Red Muds                 41

Characterization of Principal Waste streams
from U.S. Bauxite Refineries                           44

Summary of Effluent Reductions Achieved for
Bauxite Refinery Process Wastes Using Best
Practicable Control Technology Currently Available     61

Water Pollution Abatement Status and Planned
Changes  (Process and Non-Process Waste Streams)        62

Unit Mud Production Rates for Various Bauxites         75

Summary of Waste Disposal Cost Data                    76

Summary of Estimates of Future Waste Disposal
Cost Data                                              78

English/Metric Unit Conversion Table                   99
                           viii

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                            SECTION I
                           CONCLUSIONS

For  the  purpose of establishing effluent limitations guidelines
and  standards  of  performance,  the  aluminum  segment  of  the
nonferrous metals manufacturing point source category was divided
into  three  subcategories.   This  report deals with the bauxite
refining subcategory.  Consideration of the factors  of  age  and
size  of plant, processes employed, geographical location, wastes
generated, and  waste  water  treatment  and  control  techniques
employed support this conclusion.  The similarities of the wastes
produced  by  bauxite  refining  operations  and  the control and
treatment  techniques  available  to  reduce  the  discharge   of
pollutants further substantiate the treatment of bauxite refining
as a single subcategory.

It  is  concluded  that  the  best practicable control technology
currently available consists of techniques including  impoundment
(controlled  disposal  on land), the management of process waters
by methods  dependent  on  the  impoundment  capability  and  the
evaporative  capability  inherent in the bauxite refining process
as  currently  practiced,  and  various   measures   applied   to
individual waste streams including neutralization and impoundment
to  eliminate . the discharge of process waste water pollutants to
navigable waters.  Recycle of water contained in the  impoundment
area should be practiced to the maximum extent possible.

It   is   further   concluded  that  the  current  technology  of
impoundment to control the major process waste (red  mud)  allows
the  control  of  other  wastes  by  use  of the same impoundment
facilities   with   or   without   prior   treatment   such    as
neutralization.

It   is   also  concluded  that  the  best  available  technology
economically achievable applicable to existing  sources  and  the
best   available   demonstrated  control  technology,  processes,
operating methods or other alternatives applicable to new sources
aad equivalent  to  the  best  practicable   control   technology
currently available.

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                           SECTION II
                         RggOMMEKDATIQNS

The  effluent  limitations  and  standards of performance for the
bauxite refining subcategory are no discharge  of  process  waste
water pollutants into navigable waters.

The   effluent  limitations  are  considered  achievable  by  all
existing  sources  by  July  1,  1977,  inasmuch  as  two  plants
currently  achieve the effluent limitations.  The limitations are
based on the application  of  control  and  treatment  technology
meeting  the  criteria  for  best  practicable control technology
currently  available,  best  available  technology   economically
achievable,   and   the   best   available  demonstrated  control
technology, processes, operating methods, or other alternatives.

The technologies on which such effluent limitations and standards
are based consist of impoundment, in the form of a red mud  lake,
of the major solid waste from the bauxite refining processes, and
the  management of process streams and waste waters using the red
mud  lake,  other  impoundment  lakes,  and/or  the   evaporative
capability  present  in  the bauxite refining operation.  Thus, a
closed cycle system with reuse of  water  within  the  system  is
achieved.  The technologies identified also include the treatment
of  smaller  associated  waste  water  streams  by  such means as
neutralization,  with  subsequent  disposal   of   neutralization
sludges  to  the solid waste impoundment facility and the control
of remaining waste waters by impoundment, evaporation, or recycle
within the plant facility.  Treatment may involve,  for  example,
neutralization before impoundment, as for spent cleaning acid; or
the  treatment may involve evaporative cooling, as for barometric
condenser effluents.  In such cases, the  treated  effluents  are
contained within the cycle.

These  identified  waste  water control technologies are directly
related to the characteristics of the bauxite  refining  process,
which, as currently practiced, inherently involves control of the
amount  of  water  in relatively large volumes of process streams
and always contains  evaporative  capacity  for  control  of  the
composition of process streams and product drying.

Under    certain   conditions,   the   discharge   of   excessive
accumulations of rainfall may be allowed from point sources as an
exception to the above limitations and practices.  This exception
is based on the recognition that  most  bauxite  refining  plants
occupy  large  areas,  and  are located in climatic regions where
short-term (i.e.,  hours or days)  high rainfalls occur.   Further,
annual  variations  in  rainfall  may exceed the capacity of even
reasonably designed impoundment facilities.

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                           SECTION III
                          INTRODUCTION
                      Purpose and Authority

Section 301 (b) of the Act requires the achievement by  not  later
than  July  1,  1977,  of effluent limitations for point sources,
other than publicly owned treatment works, which are based on the
application of the best practicable control technology  currently
available  as  defined  by  the Administrator pursuant to Section
304(b) of the Act.

Section 301(b) also requires the acievement  by  not  later  than
July  1,  1983,  of effluent limitations for point sources, other
than publicly owned treatment  works.  Which  are  based  on  the
application   of   the  best  available  technology  economically
achievable which  will  result  in  reasonable  further  progres s
toward  the  goal of eliminating the discharge of all pollutants,
as determined  in  accordance  with  regulations  issued  by  the
Administrator pursuant to Section 304(b) to the Act.

Section 306 of the Act requires the achievement by new sources of
a  Federal  standard  of performance providing for the control of
the discharge of pollutants which reflects the greatest degree of
effluent reduction  which  the  Administrator  determines  to  be
achievable   through   the  application  of  the  best  available
demonstrated control technology, processes, operating methods, or
other alternatives,  including,  where  practicable,  a  standard
permitting no discharge of pollutants.

Section  304(b)   of the Act requires the Administrator to publish
within one year of enactment of the  Act,  regulations  providing
guidelines  for  effluent limitations setting forth the degree of
effluent reduction attainable through the application of the best
practicable control technology currently available and the degree
of effluent reduction attainable through the application  of  the
best   control   measures  and  practices  achievable,  including
treatment  techniques,   process   and   procedure   innovations,
operation   methods  and  other  alternatives.    The  regulations
contained  herein  set  forth  effluent  limitations   guidelines
pursuant  to  Section  304(b)  of the Act for the bauxite refining
subcategory of the nonferrous metals category.

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         Summary of Methods Used for Development of the
  Effluent Limitations Guidelines and Standards of Performance

The effluent limitations guidelines and standards of  performance
contained herein were developed in the following manner.  General
information  was  obtained  on all domestic bauxite plants in the
continental U.S. by means of a questionnaire.

Data for the development of effluent limitations guidelines  were
based  largely  on  site  visits  and  interviews  at  the  eight
continental U.S. plants, supplemented by published technical  and
trade  literature,  telephone  interviews, EPA technical reports,
and meetings with EPA personnel.

The industry was  first  examined  for  purposes  of  determining
whether  separate  limitations  and standards are appropriate for
different subsegments within a point source  category.   Possible
further   subcategori zation   was   considered,  based  upon  raw
materials used, processes employed, product produced,  geographic
location,  size,  and  age of plants, wastes generated, and other
factors, as discussed in Section IV.

From the on-site inspections  and  the  questionnaire  responses,
flow  diagrams,  and  information  on water management practices,
control and treatment methods, equipment and costs were acquired.
From these data, the differences
were identified.  This included:
in  raw  waste  characteristics
    1)   Analysis of the source and volume of water used  in  the
    process,  the  sources of waste and waste water in the plant,
    and type and quantity of constituents in the waste waters, as
    discussed in Section V.

    2)   Identification  of  those  constituents,  discussed   in
    Section  VI, which are characteristic of the industry and are
    present in  significant  quantities.   These  pollutants  are
    subject  to  effluent limitations guidelines and standards of
    performance.

The information, as outlined above, was then evaluated  in  order
to  determine  what  levels  of  technology  constituted the best
practicable  control   technology   currently   available,   best
available   technology  economically  achievable,  and  the  best
available demonstrated control  technology  processes,  operating
methods    and   other   alternatives.    In   identifying   such
technologies, various factors were  considered.   These  included
the  total  cost  of application of technology in relation to the
effluent reduction benefits to be achieved from such application,
the facilities involved, the process  employed,  the  engineering
aspects   of   the   application  of  various  types  of  control
techniques,  process  changes,  nonwater  quality   environmental
impact  (including  energy  requirements)  and  other factors, as
discussed in Sections IX, X, and XI.

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In  view  of  the  small  number  of  plants and the geographical
concentration of the industry,  it  was  possible  to  visit  and
acquire detailed data from all 8 of the bauxite refineries in the
continental  United  states.   Only  the  refinery  in the Virgin
Islands was not included in  the  industry  sample,  so  that  90
percent of the plants, and a larger percentage of production, was
included in the survey sample.

               General Description of.the Industry

This  document applies to the bauxite refining industry, standard
Industrial Classification (SIC) 2819 (alumina only).

Although the manufacture of aluminum  metal  dates  back  to  the
simultaneous  discovery  by  Hall and Heroult of the electrolytic
reduction process, the rapid growth of  the  industy  began  only
during  World  War  II.   Almost  overnight, the demands for this
light metal for aircraft created the  large  industry  of  today.
Because  of  this growth pattern, aluminum is one of the youngest
metal industries, and very few plants,  either primary aluminum or
bauxite refining, are more than 30 years old.

Bauxite is the principal ore of aluminum and the  only  one  used
commercially in the United States.  Aluminum is a unique metal in
that  all  of  its  purification  is  accomplished in the bauxite
refining step; none occurs in the subsequent reduction to  metal.
Thus,  the purification requirements in producing refined alumina
(A1203)  from  the  raw  ore  are  strict.   Bauxite  consists  of
aluminum  oxide,  more  or  less  hydrated and containing various
impurities, such  as  iron  oxide,  aluminum  silicate,  titanium
dioxide,  quartz,  and  compounds  of  phosphorus  and  vanadium.
Bauxite ores vary in characteristics from stony materials to soft
clays.  In general the term bauxite applies to weathered deposits
from which substances other than alumina  have  been  leached  to
leave a sufficient alumina content to make the deposit profitably
workable.  The process chemistry of alumina refining is basically
quite  simple,  and the classic Bayer process is universally used
in the United States.  In this process  the impure alumina in  the
bauxite  is dissolved in a hot, strong  alkali solution, generally
NaOH, to form sodium aluminate.  Upon dilution  and  cooling  the
sodium  aluminate  hydrolyzes,  forming a precipitate of aluminum
hydroxide  which  is  filtered  and  calcined  to  alumina.   The
operations  employed  are  those  typical  of  very  large  scale
hydrometallurgical operations, conducted in essentially a  closed
circuit,  and economically possible only with maximum recovery of
heat and a near quantitative recovery of reagents.

Bauxite refining is carried on  in  the  United  States  only  by
primary  aluminum producers.   The majority are integrated back to
the bauxite  refinery  or  to  the  mine.   Bauxite  refining  is
characteristically  conducted  in very  large scale installations.
There are only  nine  U.S.   bauxite  refineries,  owned  by  five
primary aluminum producers.  Alumina capacities, shown in Table 1,
vary from 325,000 to 1,3000,000 metric  tons (360,000 to 1,440,000

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                              TABLE 1.  OPERATING COMPANIES, LOCATIONS, CAPACITIES, AND DATE
                                        OF OPERATION OF U.S. BAUXITE REFINING PLANTS
CD
Company
Aluminum Company
of America
Raiser Aluminum and
Chemical Corp.
Reynolds Metals Co.
Onnet Corporation
Martin-Marietta
Aluminum Co.
Plant Location
Mobile, Alabama
Pt. Comfort, Texas
Bauxite , Arkansas
Baton Rouge, Louisiana
Gramercy, Louisiana
Corpus Chris ti, Texas
Hurricane Creek, Arkansas
Burns ide , Louis iana
St. Croix, Virgin Islands
Total U.S.
Date of
Commercial
Approximate Plant Capacity.
Operation Metric Tons/Day
1938
1959
1952
1942
1960
1953
1942
1958
1967
Capacity
2,270
3,200
900
2,800
2,400
3,600
2,100
1,550
900
19 , 720
Short Tons/Day
2,500
3,500
1,000
3,100
2,650
4,000
2,300
1,700
1,000
21,750
, tons alumina
Metric Tons/Year(a)
820,000
1,150,000
325,000
1,010,000
865,000
1,300,000
755,000
560,000
325,000
7,200,000
      (a)  Basis 360 day/year operation (98.6% of capacity).

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short  tons)  per year.  The locations of the eight refineries in
the continental United States are shown in Figure 1.

Alumina  production  capacity  is  in  reasonable  balance   with
consumption,  and  the period of explosive growth of the industry
appears to have subsided (see Table 2).  Over  the  last  several
years,  the  industry  has operated substantially below capacity.
The next round of growth is judged to  be  some  years  away  and
industry  consensus  appears  to  be  that  no large additions to
bauxite refining capacity in the form of new, grass-roots  plants
are anticipated over the next several years.  Future expansion is
more  likely  to  be  in  the  form of incremental expansions and
additions to existing plants.

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                                                                                           NEW ENGLANC
PACIFIC
                                        WEST NORTH CENTRAL
                                      WEST SOUTH-CENTRAL
   Annual Capacity, metric tons
  + < 500,000
  O 501,000 TO 1,000,000
  D > 1,000,000
                  Figure 1.   Location of  alumina refining  plants in the U.S.
                                                                                                ST. CR01X

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TABLE 2.  PRODUCTION OF PRIMARY ALUMINUM IN THE UNITED STATES
Year
1950
1951
1952
1953
1954
1955
&•
1956
1957
1958
1959
1960
1961
1962
1963
1964
1965
1966
1967
1968
1969
1970
1971
1972
Production,
short tons
718,600
836,900
937,300
1,252,000
1,460,600
1,565,700

1,679,000
1,647,700
1,565,600
1,954,100
2,014,500
1,903,700
2,117,900
2,312,500
2,552,700
2,754,500
2,968,400
3,269,200
3,255,000
3,793,000
3,976,100
3,905,000
4,120,000
Annual Increase
Short Tons
115,100
118,300
100,400
314,600
208,600
105,100

113,300
3 1,300 00
83,100(a)
388,500
60,400
110,800(a)
214,200
194,600
240,200
201,800
213,900
300,800
14,800
225,000
Percent
19.1
16.5
12.0
33.6
16.6
7.2

7.2
1.900
4.9(a)
24.8
3.1
5.500
11.3
9.1 '
10.4
7.9
7.7
10.3
0.4(a>
16.5
4.8
i.sOO
5.4
(a)  Decrease.
Source:   Metal
Statistics, 1972
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                           SECTION IV
                     INDUSTRY CATEGORIZATION
                          Introduction

In developing effluent  limitations  guidelines  and  new  source
performance  standards  for  a given industry, a judgment must be
made as  to  whether  these  regulations  can  be  uniformly  and
equitably  applied  to the entire industry, or whether sufficient
differences exist to  warrant  the  establishment  of  additional
subcategories.   The  factors  considered  in determining whether
such subcategories are justified for bauxite refining were:

     (1)  Manufacturing process.
     (2)  Raw materials.
     (3)  Products produced.
     (4)  Wastes generated.
     (5)  Plant size and age.
     (6)  Plant location.
     (7)  Air pollution control equipment.

As a result of a study of the literature, plant .inspections,  and
communications  with  the  industry,  it  was  concluded that the
bauxite refining  industry  should  be  considered  as  a  single
subcategory.
                       Factors Considered
Manufacturing Process
Process  Description.  The  refining  of  alumina from bauxite is
accomplished by either of two processes, the Bayer process or the
combination process.  The combination process is a  variation  of
the  Bayer  process  in that the solid residue is retreated.  The
Bayer process has been in use since about  1895,  and  is  now  a
mature technology.

l£Y®£ Process.  In the Bayer process, the hydrated alumina in the
bauxite  is  converted  to  a  soluble salt, sodium aluminate, by
reaction with either sodium hydroxide or a  combination  of  lime
and sodium carbonate to accomplish the following net reaction:
    (monohydrate)   A1203«H20 + 2NaOH --- v2NaA102 + 2H20

    (trihydrate)    A1203«3H20 •*• 2NaOH --- >2NaAl02 + UH20,

In practice this reaction is accomplished by  mixing  the  ground
ore  with  caustic  solution  in  large  iron  mixing tanks.  The
mixture is fed into pressure vessels or autoclaves, and heat  and
pressure  are  developed  by  either  steam  heating  of jacketed
autoclaves or, more generally, by direct injection of live steam.

                             13

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Conditions must be varied to suit the
but may be indicated as follows:
bauxite  ore  composition.
    monohydrate forms - a solution containing 200 to 300  g/1  of
                        Na20  and  temperature of 200 to 250°C at
                        pressures as high as 35 atmospheres   (500
    trihydrate  forms - a   solution containing 100 to 150 g/1 of
                        Na20 and temperatures of 120 to 170°c  at
                        3.40  to  a. 75  atmospheres (50 to 70psi)
                        pressure.

Most  bauxite  ores  contain   different   proportions   of   the
monohydrate  and  trihydrate  forms/ and operating conditions are
adjusted to obtain optimum processing.  The  greater  portion  of
bauxites  processed in the United states are predominantly of the
trihydrate  form,  which   permits   the   use   of   the   lower
concentrations,  temperatures,  and  pressures.   There are minor
differences  in  severity  of   processing   conditions   between
refiners, which are described later, but these differences do not
significantly influence aqueous process effluents.

The  bauxite  ore,  if  imported,  is  dried  before  shipment to
eliminate excess moisture; locally mined ore, as in Arkansas,  is
used as received, although it is stored under cover in a blending
building  before  use.  Prior to leaching, bauxite ore is ground.
An exception is Jamaican ore, which has a particle size so  small
that grinding prior to leaching is unnecessary,

The product of the above digestion process is a slurry containing
NaAl02 in aqueous solution and undissolved solids.  The insoluble
residue  remaining after the attack is commonly known as red mud,
and contains the iron oxides from the bauxite, as  well  as  some
sodium  aluminosilicate,  titanium  dioxide   (Ti02) ,  and various
other secondary impurities.

Red mud from  various  bauxites  has  different  characteristics.
These   characteristics  produce  varying  disposal  problems  at
different refineries.  For example, the yield of red mud  residue
from  Surinam  bauxite  is  low (approximately 1/3 ton per ton of
alumina product) , and the  mud  is  amenable  to  filtration  and
effective  washing  on  a  filter.   Thus,  the  final residue is
relatively easy to handle  and  disposal  area  requirements  are
moderate.   On  the  other hand, red mud from Jamaican bauxite is
produced in much greater yield, (approximately 1 ton per  ton  of
alumina) ,  due  to  its  larger  content  of  contaminants.   Its
physical  characteristics  are  such  that  filtration   may   be
uneconomic at this time, and the muds are separated and washed by
as  many  as  seven  stages  of  countercurrent decantation.  The
caustic values recovered  by  the  washing  are  concentrated  by
evaporation and returned to the process.

The  red mud may be moved as a waterborne slurry to a waste area,
known as the red mud lake, and not  further  processed.   In  the
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past,  and  still  occurring at some domestic refineries, the red
mud has been discharged to a river.  Under  an  existing  Federal
consent  decree,  these  discharges will soon stop.  Jamaican red
mud also has poor settling properties, so that  its  disposal  on
land   could   pose  serious  problems.   As  noted  in  a  later
discussion,  a  solution  to  this  problem  has  recently   been
developed to the point of commercial application.

A  generalized  schematic flowsheet of the Bayer process is shown
in Figure 2.  As described above, the separation and  washing  of
the  red  mud  residue  may  be  accomplished  by  filtration  or
countercurrent   decantation,   depending   on    its    handling
characteristics.   Another  feature  of  the  process, which is a
relatively large energy consumer, is  the  maximization  of  heat
recovery;  heat  exchangers  are  a  major feature of the process
flowsheet.  All possible caustic values are  recovered  from  the
red  mud  residues  for  return  to  the  digestion  step.   This
introduces a problem common to many closed  extractive  circuits,
namely,    buildup    of    soluble    contaminants.    Excessive
concentrations of contaminants in the sodium aluminate liquor can
interfere with alumina precipitation, and control measures may be
required.  Some contaminants can be eliminated by contact of  the
spent  liquor  with  the  red  mud  residues  in  a holding tank.
Another approach is to  pass  a  portion  of  the  mother  liquor
through a salting-out evaporation step.
combination Process.
In
	        .the  combination  process,  applied to
high-silica bauxites such as those from  Arkansas,  the  red  mud
residue  is  treated to extract additional amounts of the alumina
and to recover sodium values.  This additional extraction step is
accomplished by mixing the red mud  with  limestone   (effectively
CaC03)  and .sodium carbonate, and then sintering this mixture at
1100 to 1200°C.  The important reactions are  the  conversion  of
silica  to  calcium  silicate  and  residual  alumina  to  sodium
aluminate.   The  sintered  products  are  leached   to   produce
additional  sodium  aluminate  solution, which is either filtered
and added to the main stream for precipitation or  is  precipated
separately.   The  residual  solids (brown mud)  are slurried to a
waste lake.  A generalized flowsheet of the  combination  process
is  shown  in  Figure  3.   Although  omitted for simplicity, the
analogous use of heat exchangers and condensates shown in  Figure
2 is used.

One  feature of the combination process is that lime and soda ash
may substitute totally for caustic soda as the starting  reagent,
utilizing the familiar reaction:

    Ca(OH)2 + N3.2CO3---*- 2NaOH + CaCO3.

From   either  of  the  alternative  processes,   purified  sodium
aluminate solution is passed through heat exchangers  and  cooled
to  50 to 60°C prior to being discharged into large precipitation
vessels.  By the addition of seed material and by careful control
of composition and controlled agitation,  alumina  trihydrate  is
precipitated  in  a  controlled form,  amenable to easy separation
                            15

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    Bauxite
                                  Reconcentrated Caustic Liquor
                                                                            f Washing precipitates
                                                        Condensate - To     J  Boiler feed water
                                                                              Dilution Green Liquor
Steam
   To
 Mud Lake
                                                           Calcined Alumina
                                                               Product
           Figure 2*   Generalized diagram of the Bayer Process.
                                                 16

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    Brown Mud
     To Lake
                                                  Product         Product

Figure 3.   Generalized diagram of the Combination Process.

                               17

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and washing.  Precipitation may take  one  to  three  days.   The
precipitated trihydrate  (aluminum hydroxide)  is dewatered and fed
to  calcination  which  transforms  the  alumina to the anhydrous
crystalline form, most suitable for later use in the electrolytic
reduction to aluminum metal.  Much of the alumina produced by the
combination process from Arkansas bauxite is utilized  for  other
purposes  than  the  production of aluminum metal.  These include
refractories, electrical insulators, catalyst supports, ceramics,
abrasives and polishes, heat exchange media,  activated  alumina,
and chemical alums.

A  large  percentage  of  U.S.  production  of  gallium,  used in
transitors, results as a by-product of the refining  of  Arkansas
bauxite.  The gallium occurs in the ore as a trace element and is
recovered  from  the  process  for  its  commercial  value.  This
recovery operation is associated only with one plant operating on
a specific ore,

Water Circuit.  The general pattern of water usage  includes  the
use  of  water  for  leaching solutions, washing of precipitates,
considerable use for heat exchange purposes  in  connection  with
the control of temperatures in the reaction (i.e., steam heating,
flash  evaporation  or  multiple-effect  evaporators,  etc.), and
other  steps  of  the  chemical  extraction  process,   From  the
viewpoint  of water recirculation or discharge, the major feature
of all water circuits is the red or brown mud  lake  operated  at
nearly  all  alumina  refineries.   This  lake  is analagous to a
tailings pond in a flotation  concentrator  operation.    The  mud
lake  serves  as  a  receiver  of  solid residues, a receiver and
reservoir of process water, a point of loss  by  evaporation  and
seepage,  and a collector of rainfall.  Since some minimum amount
of water is required by the mechanics of flushing the material to
the disposal site, water also serves as the transport  medium  of
the waste portion of the ore to the lake.

In  general,  the  standard  or  combination Bayer process has no
large demand for water for air pollution control.  The  processes
used  are essentially carried out in closed vessels.  As with any
plant, a  sanitary  water  circuit  is  part  of  the  operation,
requiring  a  source  of  potable  water.   Disposal  may be to a
municipal sewer system, a plant sewer system,  or to the  red  mud
lake, with or without any form of treatment.

Although  all  plants  use  either  the  Bayer or the combination
process, no two plants are alike with respect to water  treatment
and   management   schemes.    This  makes  characterizing  plant
effluents somewhat complicated.  Location, climate, type of  ore,
and  waste  management  philosphy  all  contribute  to  different
approaches to waste water management.  Seven  of  the  nine  U.S.
bauxite  refineries  already  practice  total  impoundment of mud
wastes,  A very generalized water  flow  diagram  for  a  bauxite
refinery  practicing  total  impoundment  is  shown  in Figure U.
while the diagram shows intake water  treatment,  sanitary  uses,
and  boiler plant water streams, these streams are not considered
                               18

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                                                         Bauxite
 Rain
Runoff
                                                                          Liquor from
                                                                          Evaporation
             Stormwater
               Lake
Process
 Lake
Liquor
 To         Salts -
Mixer     To Waste
         C. W. - Cooling Water
                Figure 4.  Generalized diagram of water circuit for
                            Bayer.plant employing total impoundment.
                                               19

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to be bauxite process streams, and are shown merely
the water circuit.
to  complete
Since most of the industry uses total recycle of the main process
stream  and  normally concerns itself with only combined streams,
complete analyses for  process  waste  streams  are  not  readily
available.   The  principal  waste  stream is the red mud stream.
When this is routed to a red mud lake, as part of a closed  water
circuit,  the  parameter  of  concern  is  the  alkalinity of the
recycling lake water.  This is kept low because the  lake  serves
as  an  additional  washing  stage.   Other  ions in this recycle
stream  (e.g., sulfate)  are monitored  only  to  the  extent  that
their levels will not interfere with plant operation.

A  refinery  may  have,  in  addition to the main red mud lake, a
process water lake and a storm  water  lake.   In  addition,  the
minor  remaining  storage capacity in abandoned red mud lakes may
be utilized to dispose of  small  quantities  of  aqueous  wastes
intolerable  in  the  recycle circuit.  An example of this is the
sulfate streams resulting from acid cleaning of equipment or from
salting-out evaporators.  A process water lake can be thought  of
as  a recycle reservoir used for higher grade operations than the
red mud lake, which has a lower alkalinity and generally a higher
water quality.  It may also be used as a source of  makeup  water
for the mud lake circuit.

A storm water lake may be used to collect storm water runoff from
the plant site.  Since the surface areas encompassed by a bauxite
refinery  complex  will  range  from a minimum of several hundred
acres to a thousand acres or more, very large  volumes  of  storm
water  must  be  planned  for.  This problem is discussed in some
detail later.  Normally, a bauxite  refinery  will  maintain  its
main process water stream 'in approximate balance.  In most cases,
there  will  be  a  large  circulating load, tens of thousands of
liters per minute, but makeup additions will be relatively minor.

The prinicipal water  streams  in  a  bauxite  refinery  are  the
following:

    Red mud stream
    Spent liquor
    condensates
    Barometric condenser cooling water
    Miscellaneous cooling water streams
    Miscellaneous waste streams
    Storm water runoff.

Red Mud stream.  Red mud is the insoluble residue remaining after
extraction  of  the  alumina  from  bauxite,  in  the case of the
combination process used for Arkansas ore the  final  residue  is
brown  mud,  but the same considerations apply.  After filtration
or thickening to separate the pregnant  sodium  aluminate  liquor
from  the  red mud gangue, the mud is pumped to disposal.  If not
already at a pumpable consistency, it is first diluted.   Disposal
may be to a river (two plants)  or  to  a  red  mud  lake  (seven
                            20

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plants).   If  disposed of to a river, the mud is further diluted
to 0.5-1.5 percent solids to insure that rapid settling does  not
occur at the point of discharge.  Depending upon the bauxite ore,
the  residue  may  range  between  0.33 ton/ton of A1203 produced
 (Surinam bauxite) to 2 tons/ton   (Arkansas  bauxite).   At  17-20
percent  solids,  the  water  going  to  the  red  mud  lake will
approximate  1,900,000  to  18,000,000  liters/day   (500,000   to
4,800,000  gal/day).   Not all of this water returns to the plant
since the terminal density of the settled solids may  range  from
35  to  75 percent.  A substantial amount of water is retained in
the mud.  This is one manner in which water is rejected from  the
process water circuit.

Spent  Liquor.   After separation from the mud residue, either by
filtration or by  countercurrent  decantation  plus  a  polishing
filtration,  the  pregnant  liquor is cooled, diluted and sent to
the precipitators.  Here, fine  seeds  of  hydrated  alumina  are
added  and  after  a  cooling  period  of  1-3 days, the solution
hydrolyzes and the alumina precipitates as alumina hydroxide.

After filtration of the product  alumina  trihydrate,  the  spent
liquor  is  heated  and  concentrated for return to the digester.
Thus, the spent liquor is  not  a  waste  stream,  although  some
wastes  may be withdrawn from it.  In order to control buildup of
contaminants  which  might   either   retard   precipitation   or
precipitate  with the product in the process liquor, a portion of
the spent liquor may be passed through a salting-out  evaporator,
where  it  is  evaporated  to  low  volume  in order to eliminate
contaminants, particularly sulfates.   To prevent redissolution of
sulfates and their return to the process, the sulfate  slurry  is
normally  disposed of to an abandoned mud lake or to a land fill.
The discharge of such wastes to surface waters was  not  observed
in any plant.

In  another  scavenging  scheme,  soluble contaminants tending to
build up in  the  spent  liquor  are  allowed  to  adsorb  and/or
precipitate  on  the  bauxite slurry from the digesters.  This is
accomplished by mixing spent  liquor  with  the  bauxite  slurry,
cooling   and   diluting   it  before  filtration,  and  allowing
sufficient contact time for the scavenging to occur.  After this,
the red mud is filtered off and rejected.  This  scheme  performs
satisfactorily  for  one  producer,   and  eliminates a need for a
salting-out evaporator.

Condensates.   Numerous large  scale  evaporation  operations  are
carried  out  in  bauxite refineries.   The high temperature, high
pressure slurry from the digesters is flashed down to atmospheric
pressure for filtration or thickening.   The  still-hot  clarified
pregnant   liquor   may   be   vacuum-flashed   to  cool  it  for
precipitation.    The  spent   liquor   after   precipitation   is
evaporated  to  concentrate  it.   All of these operations produce
steam which is generally condensed in a heat exchanger to heat  a
process stream.   These steam condensates are high quality waters,
and  are  normally  utilized  for  the  most demanding plant uses
(i.e.,  boiler-feed water,  product washing,  and final  washing  of
                             21

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red muds).  However, in some plants where the water balance is in
excess, some condensates may be rejected as a waste discharge.

Barometric Condenser	Cooling Water.   As  noted in the preceding
section, cooling and concentration in  evaporators  is  a  common
feature  of  most  bauxite  refineries.   However,  one refinery,
processing high-grade Surinam bauxite by  careful  management  of
the   process  water  circuit,  is  able  to  avoid  the  use  of
evaporators and barometric condensers.  In  most  cases,  in  the
last  stage,  the multi-effect evaporators are under a relatively
high vacuum.  Surface condensers are  much  more  expensive  than
barometric  condensers  and use more water.  They are not used as
evaporators unless the vapor to be condensed  must  be  recovered
separately  from  the cooling water.  Thus, barometric condensers
are invariably used in the bauxite refining industry.  Barometric
condensers are large consumers of water, and the water management
scheme adopted will depend upon water availability, water balance
considerations, and effluent discharge requirements.

Where  a  negative  system  water  balance   exists   and   water
conservation  measures  are  practiced,  the barometric condenser
water loop will be closed,  using  the  red  mud  lake  or  other
process  water.   Where  the  process water system tends toward a
positive  balance,  or  where  ample   supplies   of   water   of
satisfactory quality are available, a once- through scheme may be
adopted, with the effluent rejected to a nearby surface water.

Water  quantities  required by barometric condensers used in this
service   are   large,   characteristically   several    thousand
liters/minute  for  each condenser,  water used may be as much as
20,000-40,000 liters/ton (5,000-10,000 gallons/ton)  of  product.
Theoretically,   the  overhead  vapors  to  be  condensed  should
approach  distilled  water  in  composition.   When   entrainment
occurs,  alkali and aluminum values will be carried over and will
appear in the effluent from the  barometric  condenser  hot-well.
If  this  is discharged to a receiving water containing dissolved
magnesium or calcium compounds, these  will  be  precipitated  as
visible  white hydroxides.  Normally, entrainment will be minimal
from a well designed  and  operated  evaporator  and  will  reach
unsatisfactory    levels    only   during   periods   of   upset.
Incorporation of suitable demisters in the evaporator vapor space
will further minimize entrainment.

Miscellaneous  Cooling  Water	Streams.   Normally,  the  various
cooling  streams  in  a bauxite refinery come from air compressor
aftercoolers and  various  cooling  duties  associated  with  the
rotary calcining kilns.  These are characteristically non-contact
services.

storm Water Runoff.   storm  water  runoff  from bauxite refinery
sites may comprise a significant volume.  This results  from  the
large  ground areas occupied and general location in regions with
high and occasionally torrential rainfalls.  There are  no  known
data  on  the changes in alkalinity of runoff water as a function
of amount of rainfall  for  a  single  storm,  but  it  would  be
                            22

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anticipated  that   the   first   portion  of a rain would  remove  any
superficial alkaline dust, and  that  alkalinity  of  the   runoff
would decrease thereafter.

If  the  plant  areas  were smaller or  refineries were  located in
more  arid  areas,  storm  water  runoff  would  be   of    little
consequence.   However,  all bauxite refineries in the continental
United  States  have  histories  showing  storm-type    rainfalls.
Illustrative  of  the  maximum  rates   of  rainfalls which  can be
experienced in these regions are some historical data   from U.S.
Weather Bureau Records  (Table 3).  For  example, during  this study
about 60 cm (24 in) of rainfall were accumulated over a three-day
period in one area  of the Texas Gulf Coast  (3).

Current  technology  for control of storm water runoff  appears to
be the  selection   of  a  maximum  rainfall  rate  which  can   be
collected,  and  to  divert  storm  water runoff, accumulating at
greater  rates  than  this,  by   overflow   weirs   or  similar
arrangements.   One  plant,  for  example,  can collect and store
rainfall up to a rate of 7.6 cm (3 inch) per  hour;  rainfall   at
rates  greater than this is diverted to a nearby waterway.   Storm
water runoff from rains exceeding this rate are considered  by  the
plant  to  be  either  essentially  uncontaminated   by  process
pollutants,  or  so  extremely  dilute  that any contaminants  are
below significant levels.

Mass Water Balance in a Bauxite Refinery.  A better understanding
of the state-of-the-art of treatment technology and  the  factors
affecting the feasibility of total impoundment is gained when  the
possible  water  gains  and  losses  in  a  bauxite  refinery  are
considered.  Although these will vary, the  following   summarizes
the main sources of gain and loss:

Water Gains.   In most cases, refineries processing imported ores
will not gain water from them, since these ores are dried   before
shipment  and normally stored under cover before use.   if outdoor
storage piles are used, some moisture will enter  with  the ore.
Domestic ore (Arkansas)  is not dried before processing, and there
is  a  definite  water  gain from this source.  Almost  all  plants
have a fresh water  intake,  although  this  quantity   is   highly
variable.    Water  intake  may  be  needed  for potable purposes,
boiler feed water, barometric  condensers,  washing  precipitated
aluminum hydroxide, or makeup for water losses from the circuit.

The  other  large  and  uncontrollable  cause  of  water  gain  is
rainfall.   Since bauxite refineries occupy  large  areas,   runoff
quantities  can significantly affect the water balance.  There  is
some possibility of diverting rainfall on plant grounds  so  that
it  does  not enter the water circuit.  However, rain which falls
on mud lakes enters the water circuit directly,  and can represent
a sizable  water gain.   For example, 31 cm (1 ft)   of  rain  on  a
40.5  ha  (100  ac)  mud lake is equal to a little over 125,000,000
liters (33,000,000 gal), and can accumulate in as  little  as   24
hours (Table 3).
                            23

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                                             TSELE 3.  MAXIMUM RAINFALLS
                                                                         (a)
                                                         Cumulative Rainfall,  cm (in.)
        Location
                            1-hr
2-hr
3-hr
6-hr
12-hr
24-hr
    Little Rock, Arkansas    7.62 (3.00)    11.68  (4.60)    17.32 (6.82)    19.50 (7.68)   20.80 ( 8.19)   24.33 ( 9.58)
            Year              -<	  1955 	>-        1913            1913
    Mobile, Alabama
            Year
                         8.91 (3.51)   11.35  (4.47)    12.70 (5.00)    20.88 (8.22)    32.97 (12.98)   33.93 (13.36)
                            1947            1922            1900           1911           1900            1955
to
Baton Rouge, Louisiana   6.12 (2.41)    9.27  (3.65)    11.56 (4.55)    12.34 (4.86)    12.60 ( 4.96)   21.34 ( 8.40)
        Year                1959        •<	 1954	»-        1947

New Orleans, Louisiana  11.97 (4.71)   14.91  (5,87)    16.61 (6.54)    21.89 (8.62)    32.41 (12.76)   35.58 (14.01)
        Year             -«	 1953 	*-         1927            1929        -«	 1927 	*-

Corpus Christi, Texas    9.22 (3.63)   11.81  (4.65)    13.59 (5.35)    15.95 (6.28)    17.78 ( 7.00)   20.98 ( 8.26)
        Year                1928            1960            1956         	 1931 	>-        1924
    Victoria, Texas
            Year
                         7.87 (3.10)   11.81  (4.65)    15.62 (6.15)    18.67 (7.35)    20.19 ( 7,95)   22.02 ( 8.67)
                         -*	 I960  	»-
    (a)  Data through 1961.
    Reference:  The Water Encyclopedia.

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 Water Losses.
 the~following:
Water losses in a bauxite refinery may arise from
    Drying and calcining of product.
    Red mud.
    Evaporative cooling of green liquor,
    Concentration of spent liquor.
    Evaporation from lakes,
    Seepage*
    Red mud calcination  (combination process),

Drying and  calcining  of  product:   The  precipitated   aluminum
hydroxide,  Al(OH)3, is filtered from the spent  liquor, washed to
displace the entrapped caustic  solution,  dried,  and  calcined.
Assuming a 50 percent solids cake from the filter, a ton  of water
is  evaporated for each ton of alumina product  (i.e., 520 to 3600
kkg (575 to 4000 ton) water).

Red mud:  The red or  brown  mud  carries  water,  which  is  not
reclaimed.   Even  when fully consolidated, the  mud in a  lake may
contain more than 50 percent moisture.  This  is  approximately one
ton of water loss for each ton of mud.  This  loss will vary on an
alumina basis due to the range for various bauxite ores   of  from
0,33 to 2.0 tons mud per ton A1203 produced.
                                                           «.
Evaporative cooling of green liquor:  Evaporation is a ubiquitous
operation  in a bauxite refinery.  It occurs  first ,in cooling the
bauxite slurry issuing from the digesters.  Typically, the  green
liquor  slurry from the digesters will be blown  down (flashed) to
atmospheric pressure in several stages.  The  vapors released will
be condensed and reused as boiler feed water,  cake  washing,  or
dilution  of  the  filtered pregnant liquor before precipitation.
It is not normally discarded.  The general system  was  described
by  Hudson,  (5)  and is illustrated by the flowsheet in Figure 5.
Although  the  slurry  must  be  cooled  before  going    to   the
precipitators,    recovery   of   heat  is  an equally  important
objective.  The steam from the flash tanks is used in  the  shell
side  of  tubular  heat  exchangers  to  heat  the process liquor
recycling to the digesters.  As indicated by  Figure 5, a  portion
of  the liquor is diverted through the mixer where the liquor and
bauxite are combined.

The final stage of cooling the green liquor before filtration  or
countercurrent  decantation  of  the  mud  may be performed by an
evaporator operating  under  vacuum.   The  vapors  released  are
condensed   in   a   barometric  condenser.    There  are  several
possibilities for disposal of the mixture of  cooling  water  and
process  condensate  from  the  barometric  condenser.   It may be
contained in a totally closed circuit, with the  effluent  going to
the lake or cooling tower from which the condenser cooling  water
is  drawn.  The barometric condenser may use  once-through cooling
water, in which case the mixed effluent is  discharged  from  the
plant to a waterway and represents a water loss.
                           25

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                                                        Bauxite
Digester
    0
                         Tubular
                          Heat
                        Exchangers
               Steam	
                  Condensate
                                             Mixer
r    Tl
+*	i—A_,
                                             Reconcentrated
                                                Spent
                                                Liquor
            Slurry from Digester
                                  Flash
                                  Tanks
                                                                          Digested Slurry
                                                                         - to Clarification
               Figure  5.   Flowsheet of  digestion  and  heat recovery system.
                                                26

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 The  pregnant   liquor   filtrate   from  the  red  mud  separation  step
 also needs  further  cooling  before  going   to   the   precipitators.
 This    cooling   may be  done  through evaporation  or   in   heat
 exchangers   against the  cold   spent   liquor   enroute    to    the
 evaporators.     The   effluent    from   the barometric   condenser
 generally will  go to a reservoir for recycle to the process.

 Concentration of spent liquor:   A large heat duty   is associated
 with  the   concentration  for reuse of the spent liquor  filtrates
 from separation of  the aluminum  hydroxide  product  from the mother
 liquor.   Typically,   the  multistage   evaporators  used    will
 concentrate the liquor from about 150 g/1 to  about 170  g/1 Na203
 (113 g/1 to 128 g/1 NaOH) .   Again,  the   vapor from the  first
 stages  will generally  be condensed against some cold process
 stream, but the last stage  will  be under   high  vacuum   and   will
 utilize  a  barometric  condenser.   Depending on the  balance in the
 water circuit and the  availability of   the large   quantities of
 water   needed   for  a   barometric condenser, the effluent will be
 discharged  to a waterway  or recycled to an impoundment   lake in
 the plant water circuit.  If efficiently operated,  there will not
 be  any  appreciable carryover of caustic  from an evaporator  to a
 barometric  condenser.

 Evaporation from lakes:   The area of a bauxite refinery's red mud
 lake may vary from,  40  to  800 ha  (100 to 20CO ac).   In addition, a
 plant may have  a series of  lakes  (process lakes,   clear  water
 lakes,   storm   water   lakes,  etc.)   used for other   purposes.
 Depending on the geographical location of  a refinery, these lakes
 may serve as net evaporators or  net collectors.    In more   arid
 locations along the Texas Gulf Coast,  these lakes may be a source
 of  water   loss;  further east,  in southern Louisiana or Alabama,
 the reverse may be  true.  Table  4 depicts  this situation, showing
 average rainfall and mean annual  lake evaporation,  the latter
 data taken  from Figure 6.

 Seepage:  seepage   from lakes is a possible minor source of water
 loss.  However,  in  constructing  a  lake, .  attempts   are   made to
 insure  that the   bottom  provides an impervious layer.  A ditch
 surrounds the red mud  lake  dikes,  in which any minor seepage  will
 be collected and pumped back to  the lake.   General  practice is to
 monitor this ditch by   survey  wells   located   around  the  lake.
 Ground water does not  exit  the property through a recognizable or
 identifiable outfall.    Based   on information supplied by plant
 operators,  there is  no  evidence  to   suggest  that this  is a
 pollution problem  to  either surface or ground waters.

 Red  mud  calcination:   One special case  of water  loss  is in the
 red mud  calcination   peculiar   to combination process  bauxite
 refineries.   The  red  mud from  the  first stage  is retreatd by
 mixing with soda ash and  lime and than  calcined.    The   red   mud
.underflow   from  the  countercurrent   decantation   unit,  at   25
 percent  solids,  generally will   undergo  pressure  filtration,
 possibly to 40-50 percent solids,  to reduce the  water content and
 the evaporative  load.   This will  represent  a loss from the system
 of about a  ton  of water per ton  of red  mud  processed.
                          27

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                                        TABLE 4.   RAINFALL AND EVAPORATION DATA
to
00
Mean Annual
Lake
Rainfall Data'3^
Location
Little Rock, Ark. /Robinson AAF
Little Rock, Ark. /Adams Field
Mobile, Ala. /Bates Field
Mobile, Ala./Brookley AFB
Baton Rouge, La. /Downtown
New Orleans, La./Moissant Field
Corpus Christ! , Tex./Cuddihy Field
Matagorda Island, Tex.
cm
128
126
158
154
133
146
72
94
(in.)
(50.3)
(49.5)
(62.2)
(60.7)
(52.3)
(57.4)
(28.3)
(37.1)
Years
9
23
90
12
16
84
19
12
Evaporation^)
cm
109
119
124
124
140
140
(in.)
(-43)
(-47)
(-49)
(-49)
(-55)
(-55)
Average Net
Accumulation
cm
18
37
9
22
68
46
(in.)
<~7,
(-14)
( ~3)
( ~9)
(-27)
(-18)
              (a)  U.S. Naval Weather Service World-Wide  Airfield  Summaries.'^'

              (b)  The Water Encyclopedia(^)  (see Figure  6).

-------
                                   Figure 6.   Mean annual evaporation  in the United States.
                                                           (Source: U.S. Weather Bureau)
                                                         [Values in inches for period 1946-55-1
VO

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Summary .   As  described  in  the  foregoing  paragraphs, there is
fundamentally only one process for refining  bauxite,  the  Bayer
process.    The  combination  process,  a  variation  of the .Bayer
process,  retreats the red mud waste from  the  Bayer  process  to
recover  additional  aluminum  and alkali values.  Upon review of
both  methods,  it  is  concluded   that   the   differences   in
manufacturing processes do not warrant further subcategorization.

Various  means of condensation create varying quantities of waste
water.  When barometric condensers are utilized, large quantities
of cooling water are required which may create  an  imbalance  in
the  water circuit.  While these differences may justify adoption
of  a  different  configuration  or  management  of  some   water
circuits,  there  is  no  justification  for  establishment  of a
subcategory to provide for them.

Raw Materials

The raw material for all U.S. alumina refineries is  bauxite,  an
ore  of aluminum which consists of hydrated alumina  (A1203/ 3H20) ,
known as gibbsite or hydrargillite.                      *~

This  classification  is  of  great   practical   importance   in
processing,  as  the  methods  used to treat bauxites in order to
extract pure alumina are based on  attacking  the  bauxites  with
caustic soda.  The trihydrate is much more soluble in alkali than
are  the  monohydrates , and processing conditions are appreciably
milder.  Most of the bauxite processed in the  United  States  is
predominantly of the trihydrate variety.

The  suitablity  of  a  bauxite  as  a  raw material for aluminum
extraction depends on its alumina content and on its  content  of
combined  silica in the form of kaolinite, A1203/ 2Si02- 2H20 .  Not
only does such a silicate, if present, tie up~"a certain amount of
alumina that cannot be extracted, but, in the course of treatment
entails a heavy and expensive loss of caustic soda in the form of
insoluble sodium aluminum silicate compounds  (such  as  sodalite,
3^20.^1203/68102/2^01,   and   cancrinite,   (Na,K) (Al,Si) 204.) .
Each kilogram of "SiO^  in  the  bauxite  involves  the  loss ~"of
approximately  1  kilogram  of  A120_3  and 0.6 to 0.7 kilogram of
The composition of the bauxite used in alumina production  varies
a great deal.  The variations generally fall within the following
limits shown in Table 5,
                             30

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           TABLK 5.  RANGE OF COMPOSITION OF BAUXITES
                     FOR ALUMINA PRODUCTION
    Composition
 Weight Percent
     f total
Si02_, free and combined
Fei03
Ti02
p2.°5.' V2,05' etc-
H20, combined
 40 to 60
  1 to 20
  7 to 30
  3 to . 4
0.05 to 0.20
 12 to 30
Reference:  Kirk-Othmer  (7)

                              31

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There  are  other  ores  of aluminum, such as nepheline, a double
silicate of alumina and an alkali metal, and alunite,  a  hydrous
potassium aluminum sulfate, K(A10) 3_(S04:)2^3H2p.  The treatment of
these ores is complicated and expensive, and"no other ores except
bauxite are commercially processed in the United States.

Most  of  the  bauxite  used  in  the  United States is imported.
Jamaica and Surinam (formerly Dutch  Guiana)  are  the  principal
suppliers.   Some  comes  from Australia, Guinea (formerly French
Guiana), Haiti, and South America.  The only commercial  deposits
in the United States are in Arkansas, and are used by two bauxite
refineries  located  nearby.   The differences in ore composition
mentioned previously are illustrated by typical analyses supplied
by the producers for these ores (as shown in Table 6).

The silica content in imported ores is not high enough to warrant
other than the basic Bayer process.   It  is  less  expensive  to
accept the losses of alumina and  caustic discussed above than to
attempt  to recover them.  However, the average silica content of
Arkansas ores is now in the 13 to 20 percent range.  Ores as  low
as  6  percent  Si02  occurred in the past in the area, but these
were "high-graded" (Turing World War II.   There  is  considerable
variation  over  this  mineralized  area, and selective mining is
practiced to produce a uniform feed material.

In order to avoid the high losses of alumina  and  alkali,  which
would  occur  as  a  result  of  the  high  silica  content,  the
"combination" process is employed for  Arkansas  ores.   In  this
process  the  red  mud residue from the Bayer process, containing
alumina  and  soda  values  insolubilized  as   sodium   aluminum
silicate,  is  sintered with lime soda ash.  The lime ties up the
silica as  calcium  silicate,  and  the  soda  ash  promotes  the
formation  of  sodium  aluminate,  which  is then leached out and
precipitated in the usual fashion.  The resultant  solid  residue
from  the  second  leaching is known as "brown mud".  Its calcium
silicate content confers some of the properties  of  a  hydraulic
cement  upon  it,  and brown mud can be safely accumulated in mud
lakes to'considerable heights.

In summary, the bauxite ores processed in the United  States  are
essentially  all  trihydrate-type  ores, more amenable to control
and treatment  than  the  monohydrate  ores  common  to  European
deposits.   Even  in  the  ores  least  amenable to treatment, 80
percent of the alumina is of the trihydrate form.  The best  ores
contain  95  percent  of  the alumina in trihydrate form.  In any
case, the chief effect of the higher monohydrate  content  is  to
require  a higher temperature and pressure in the digesters.  The
quantity and quality of wastes  generated  is  not  significantly
affected.   Accordingly,  a  subcategory  based upon raw material
differences is not warranted.

If imported bauxite  ceases  to  become  freely  available  at  a
competitive  price,  other  domestic  ores  such  as nepheline or
anorthosite, CaO -Al^OS^SiO^, may be used.   No  domestic  plants
                             32

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TABLE 6.  CHARACTERISTIC ANALYSES FOR VARIOUS  BAUXITES
Weight Percent

A1203, total
SiOa
Fe203
Ti°2
F
F205
V205
H20, combined
A 12^3) trihydrate
A ^03, monohydrate
Jamaican
49.0
0.8
18.4
2.4
--
0.7
- _»
27.5
40-47
2-9
Surinam
59.8
3.8
2.7
2.4
-_
0.06
0.04
31.2
59.6
0.2
Arkansas
48.7
15.3
6,5
2.1
0.2
._
--
25.8
34.1
14.6
Guiana
58.6
4.9
4.1
2.5
0.02
--
_.
29.6
52.7
5.9
                       33

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currently  are  using  or plan to use such raw materials, but one
producer has begun exploratory investigations.

Products Produced

The  only  product  from  U.S.  bauxite  refineries  is  purified
alumina.  Normally, this is calcined for use in the production of
aluminum  metal.  There are no significant differences in product
between  the  various  producers.   Minor  quantities  of   other
aluminum   compounds   are   produced,   but   the  tonnages  are
insignificant.    There   is   no   justification   for   further
subcategorization based on products.

Wastes Generated

The  major  process waste associated with the refining of bauxite
is the mud residue.  There are differences between  the  residues
from the Bayer process (red mud)  and the residues left after this
mud is retreated by means of the combination process (brown mud).
These  differences  do  not  appreciably  alter  the  problem  of
disposal.  There are  also  differences  in  the  amount  of  mud
generated  per  ton of alumina produced depending upon the source
of the  bauxite.   Only  1/3  ton/ton  of  alumina  results  from
processing   Surinam  bauxite;  about  1  ton/ton  from  Jamaican
bauxite; and 2 to 2-1/2 tons/ton for Arkansas bauxite.   However,
these  differences change the size, not the nature of the problem
of disposal.

The bauxite refining industry has reduced itself to one  category
for  mud  wastes.   Seven  of  the  existing nine U.S. refineries
practice total impoundment of the mud slurry waste  stream.   Two
refineries  currently  are  discharging the mud residues into the
Mississippi River.  Under a consent  degree,  these  plants  must
convert  to the equivalent of impoundment by 1975.  Thus, by 1975
total impoundment  of  mud  wastes  will  be  universal  for  the
industry.

As indicated by the process description in the preceding section,
the  red  mud  wastes  are  accompanied by alkaline process water
containing some unrecovered aluminum.  Because of the  similarity
of  process  technology,  the  differences from plant to plant in
composition of the aqueous phase  are  minor.   With  respect  to
treatability  of  red  (brown)  mud  wastes,  the differences are
insufficient to warrant establishment of subcategories  based  on
types  of  mud.   Substantiation for this judgment is provided by
the current, or soon to be successful, total impoundment of  each
of the various types of mud.

All  bauxite refineries use sulfuric acid for removing scale from
heat exchangers,  as  well  as  filtration  and  other  types  of
equipment.   The  resultant  spent  acid is generally neutralized
with the alkaline mud waste in an active or abandoned  mud  lake.
Other wastes which may be generated by bauxite refineries include
the following:
                               34

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    Boiler blowdown.
    Cooling tower blowdown.
    Water softener sludges.
    Sanitary waste effluents.

None  of  these  effluents  is unique to bauxite refining.  Since
none of .these are process streams, they are not , the  subject  of
effluent limitations.

Plant Size and Age

The  aluminum industry and the bauxite refining industry are new,
relative to the other  primary  metals  industries.   The  oldest
bauxite refinery dates back only to 1938 and two were constructed
during  World War II by the Defense Plant Corporation.  Four more
refineries were constructed in the 1950's.  Since then, only  one
has  been  constructed  and it began operation in 1967.  The only
old bauxite refinery was shut down in 1957 and dismantled.

Because all refineries use bauxite  ore  and  employ  either  the
Bayer or combination process, there is a great deal of similarity
between plants.  One primary aluminum producer designed and built
its  own  three  plants  and the two erected during World War II.
Many components are of identical design.

The smallest bauxite refinery has a production  capacity  of  900
kkg (1000 tons)/day of A1203.  The largest has a capacity of 3265
kkg  (3600  tons)/day.   A Fourfold difference in plant size does
not significantly affect the quality or quantity of  waste  water
produced   or   its  amenability  to  treatment.   Thus,  further
subcategorization on the basis of the age or size  of  refineries
is not justified.

Plant Location

As  illustrated  by  Figure 1, two bauxite refineries are located
near the domestic bauxite deposits  in  Arkansas.    The  rest  of
those  in  the continental United States use imported bauxite and
are located in the South.  These locations are accessible to deep
water shipping, either  'directly  on  the  coast,   or  along  the
Mississippi River.

The  relationship  between annual rainfall and annual evaporation
may be significant for some plants.  In some locations,  such  as
western   Texas,   annual  rainfall  averages  about  72  cm  (30
inches)/year, while the annual evaporation rate is about  140  cm
(60  inches)/year, a net deficit of 68 cm (30 inches)/year. Thus,
management of red mud lakes  and  water  balances  in  the  water
circuit  is  simplified.   In  southern  Louisiana  and  Alabama,
average  annual  rainfall  is  approximately  130-160  cm  (51-62
inches)/year,  while  evaporation  averages only about 120-140 cm
(47-55 in)/yr, a net gain of 10-20 cm (4-8  in)/yr  of  rainfall.
This excess water complicates the management of the red mud lakes
and may pose a disposal problem.
                               35

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Rainfall   is   important   because   of  the  large  land  areas
characteristic of a bauxite refinery  complex.   Apart  from  the
rainfall   collected   directly   in  the  red  mud  lake,  which
unavoidably enters the water circuit, runoff from the plant  site
must  also be managed.  Since the plant area may comprise several
thousand acres, the quantities of water collected can be large.

However, the differences between  rainfall  and  evaporation  for
various  locations  are  susceptible  to  control  by  design and
process management.  Runoff from plant sites can be discharged to
its normal water course, if the plant is  designed  to  segregate
process  waste  waters  and runoff.  By allowing the discharge of
net rainfall for each monthly period from  the  overflow  of  the
impoundment  areas, a subcategorization based upon plant location
is not necessary.

Air Pollution Control Equipment

The principal air pollution problem in a bauxite refinery is  the
dust  from the calcination of the alumina product.  Electrostatic
precipitators have been used in the past,  but  have  not  always
provided  adequate  control.   New  designs for precipitators are
being developed.  Baghouses are also used for final cleanup after
electrostatic precipitators.  No plants use or plan  to  use  wet
scrubbers  on  this  operation.   Where wet scrubbers are used on
other dust producing operations (e.g.,  lime  kilns  or  conveyor
transfer  points), the waste effluent normally is recycled to the
process or is included with the main red mud flow.   Compared  to
the   very   large   volumes   of  red  mud,  these  streams  are
insignificant.   Air  pollution  control  equipment  in   bauxite
refineries  appears  unlikely to have any significant effect upon
aqueous effluents, and no further subcategorization is warranted.
                               36

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                            SECTION V
                     WASTE CHARACTERIZATION
                          Introduction

The dominant waste from a bauxite refinery is the gangue material
from  the  ore, known as red or brown mud, which is produced on a
very large scale  (500 to nearly 4,000 kkgs per  day).   The  most
common   solution   to  this  red  mud  waste  problem  is  total
impoundment, but the tonnages to be  disposed  of  can  make  the
problem  difficult.   Compared to the other wastes characteristic
of bauxite refining, the red mud waste stream  poses  only  minor
problems.
               Characteristics _of Types of Wastes
Red Mud wastes
Depending  upon  the  type  of  bauxite  used,  from  1/3  ton to
approximately one ton of red mud will  be  produced  per  ton  of
alumina.   In  the  case of brown mud from Arkansas bauxite, this
increases to 2 to 2 1/2 ton/ton.  The red mud is the major  waste
stream from a bauxite refinery.  It will generally issue from the
washing  thickeners at approximately 17 to 20 percent solids, and
be pumped to a disposal lake.  Iron  impurities  impart  the  red
color  to the mud.  If derived from Jamaican or Arkansas bauxite,
the red mud may contain as much as 50 percent iron.

Table 7 shows a typical chemical analysis of the insoluble solids
in Jamaican red mud.  98.5 percent of the  material  consists  of
the  oxides of only eight elements plus water and carbon dioxide.
The remaining 1.5 percent consists  of  the  oxides  of  metallic
elements,   such   as  MgO,K20,Cr203,ZnO,Zr02,NiOj2,V2C5,SrO,  and
others.
                             37

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             TABLE 7.  RED MUD INSOLUBLE SOLIDS  (a)
Loason Ingition (LOI)
Si02
A1203
Fe203
P205
CaO
Na20
Ti02
Mn02
Miscellaneous
Percent

  11.0
   5.5
  12.0
  49.5
   2.0

   3.5
   5.0
   1.0
   1.5
8.0
 (a) Specific gravity = 3.6
Reference: Rushing  (8)

"Poor  crystallization  and  agglomeration  have   made   mineral
identification  of  red  mud  very  difficult.   By  using  X-ray
diffraction, petrographic  microscopy  and  differential  thermal
analysis,  some  of  the  mineral compounds have been identified.
Predominant compounds  are  iron  oxides,  hematite,  Fe203,  and
hydrated  iron  oxides  such  as goethite, FeO(OH), and limonite,
FeO (OH)»nH20  +  Fe.203«nH2C.   Other  iron  compounds   such   as
jacobsite,  MnO«Fe2037 magnetite, -Fe304, hercynit, FeO»Al203, and
ilmenite, FeO», Ti02 have been tentatively identified.   Aluminum
is  present  with silica in tentatively identified compounds such
as pyrophyllite, Al2O3*USiO2»H2O,  sarcolite,
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 TABLE 8.  RED MUD SLURRY SOLUBLE SOLIDS
A12°3
NaOH
NaCl
Na2C204
Specific gravity
PH
BOD
COD
  2.5 g/kg liq,
  3.7 g/kg
  1.6 g/kg
  0.4 g/kg
  0.7 g/kg
  0.1 g/kg
  1.008
 12.5
  6 ppm
148 ppm
Reference:   Rushing
                   (8)
   TABLE 9.   SCREEN ANALYSIS OF RED MUD
Screen
Mesh

-10
-20
-50
-100
-200
-325
+10
+20
+50
+100
+200
+325

Percent
Dry Solids
0.0
0.2
0.8
0.8
0.8
1.9
95.5
Reference:  Rushing
                   (8)
                    39

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    "The small particle size of the  red  mud  is  similar  to  a
    material  of  about  3  percent  fine sand, 62% silt, and 35%
    clay, but since few true clay minerals are present,  the  red
    mud will present physical properties of salty fines.  Red mud
    slurry   is  moderately  thixotropic  in  that  the  apparent
    viscosity  decreases  or  the  fluidity  increases   as   the
    cumulative shear rate increases and acts as a Bingham plastic
    in   that  a  yield  stress  must  be  exceeded  before  flow
    commences.

    "Jamaican red mud will reach a maximum  compaction  of  about
    35%  solids if allowed to settle and compact below a layer of
    water.  If the mud slurry is allowed to dry in  air,  surface
    cracking   will  start  at  about  28%  solids.   Desiccation
    fissuring  will  continue  on  air  drying  with   a   volume
    shrinkage.   The  volume  of one ton of red mud solids at 80%
    solids will be 1/4 the volume required for one ton of mud  at
    35%  solids.   The  air-dried  mud  will  reslurry  at solids
    contents less than 60%; however, if the drying  is  continued
    to  solids  contents  greater  than  60%,  the dessicated mud
    agglomerates will not reslurry although  there  may  be  some
    parting of the lumps at fissure or crack planes."  (8)

Red  mud  wastes  contain significant amounts of suspended solids
and alkalinity.  Depending upon the number of mud washing stages,
the water associated with the mud may contain 3-10 g/1 alkalinity
(expressed  as  Na^CO^),  and  1-3  g/1  of   sodium   aluminate.
(Convention  in  the  U.S.   alumina industry is to express total
alkalinity, including both NaOH and Na£C03 as
The ideal solution to the red mud problem would be to  develop  a
use  for  it.   An obvious possible application utilizes its high
iron content (Table 10).  Fursman, et al (10) describe a  process
based  on  sintering  the  red  mud with carbon and limestone and
melting the sinter in an electric furnace to produce a low purity
iron which could be further processed into steel.   Although  the
basic  process  has  been  further  developed (11) it has not yet
found commercial application.  It may have some economic value in
countries which have bauxite refineries, but produce little or no
steel.

Other  investigators  have  examined  its  applicability  to  the
manufacture  of  portland  cement, bricks, and road construction,
(10) (12),  But no domestic markets have yet been developed which
will economically justify processing the waste  red  mud.   Total
impoundment  however,  affords the opportunity for reclamation of
the red mud  when  an  economic  recovery  process  and  adequate
markets are developed.

gleaning Acid Wastes

The  thermal  efficiency  of  a  bauxite  refinery,  an important
economic item,  depends significantly upon the efficiency  of  the
many  heat  exchangers  used  to  transfer  heat from hot to cold
process  streams.   Many  of  the  streams  contain   substantial
                              40

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           TABLE 10,   RANGE OF CHEMICAL ANALYSES  OF RED MUDS
Wetszht Percent
Component
Fe2°3
A1203
Si02
Ti02
CaO
N820
Loss on
Ignition
Alcoa
Mobile, Ala.
(Surinam)
30-40
16-20
11-14
10-11
5-6
6-8
10,7-11.4
Reynolds
Bauxite, Ark.
(Arkansas)
55-60
12-15
4-5
4-5
5-10
2
5-10
Reynolds
Corpus Christ!, Texas
(Jamaica)
50-54
11-13
2.5-6
trace
6.5-8.5
1.5-5.0
10-13
Reference:  IITRI Project No.  G6015
                                   (9)
                                 41

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quantities of dissolved solids, and scaling of exchanger surfaces
is  a  recurring problem.  Acid cleaning is universally employed,
generally with sulfuric  acid.   Small  quantities  of  inhibited
hydrochloric  acid or acetic acid are sometimes used.  Scaling is
also a problem with filtration equipment and filter  cloths,  and
similar  cleaning  procedures  are used.  Normally, the resulting
spent acid is primarily a solution high  in  sulfates,  but  with
only  low  to  moderate  free acid concentrations.  These sulfate
solutions  are  disposed  of  by  most  plants  to   active   or,
preferably,  to  abandoned  mud lakes where the neutralization is
completed.   In  a  few  instances  they  are   neutralized   and
discharged  to  waterways but this procedure is being replaced by
impoundment.  The quantities of sulfuric acid used are not large,
averaging about 0,453 to 0.907 kkg (0.5 to 1.0 tons)  of acid  per
day.

Barometric condenser Effluents

Possible  pollutants from the barometric condensers operation are
heat and alkalinity.  As described  earlier,  sizable  barometric
condensers are found at nearly all bauxite refineries, where they
are  used  on  the  evaporative  coolers  and  the  spent  liquor
evaporators.  Illustrative of the heat duty are the data from one
plant with five spent liquor evaporators.   Here  the  barometric
condensers  averaged 126 I/sec {2000 gal/min)  and the temperature
rise was approximately 1U°C  (25°FJ, for  a  total  heat  duty  of
about  31 million kg-cal/hr  (125 million BTU/hr).  Entrainment of
significant  amounts  of  alkali  to  the  barometric   condenser
effluent  should  be negligible except during periods of upset or
abnormal operation.  However, barometric condenser effluents will
tend to have a pH over 7.

Thermal Effluents

Air compressor aftercoolers may also contribute heat  to  process
streams,  compressed air is generally used in sizable amounts for
agitation  in  the  numerous precipitators in a bauxite refinery.
Air from compressors is frequently  passed  through  water-cooled
aftercoolers  to remove the heat of compression and cool the air.
This service is a non-contact cooling application  and  the  only
pollutant the cooling water can acquire is heat.

similarly,   there   may   be  other  non-contact  cooling  water
applications, from which thermal discharges may result,  such  as
seal rings on rotary calcining kilns.  Heat discharges from these
ancillary services are nominal,

Miscellaneous _Wastgs

Several  bauxite  refineries operate rotary lime kilns to produce
the lime needed to compensate for the  carbonate  accumulated  in
the  process liquor, or for use in the combination process,  some
plants use wet scrubbers  on  these  lime  kilns,  from  which  a
potential  waste  stream results, but the resultant hydrated lime
                             42

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slurry is invariably fed back to the process in order to
the contained lime, and is never discharged.
      utilize
One  miscellaneous waste stream from a bauxite refinery difficult
to characterize is  the  "housekeeping"  or  "hose-down"  stream.
This  results from minor spills, leaks, and wastes resulting from
clean-ups.  In most plants the inplant drains  are  connected  to
the  storm sewer, which may be discharged to the storm water lake
or to the red mud lake.

In most plants, all  process  areas,  where  aqueous  spills  are
possible,  are  floored  with  concrete; curb about 6 inches high
surrounds the entire area.   Any  spill  is  thus  contained  for
recovery  and  controlled  disposal.  Several other waste streams
may also be associated with the operation of a bauxite  refinery.
Examples of these are:

    Sludge from treatment and softening of the raw intake water.

    Spent regenerant from ion exchange treatment of intake water.

    Boiler blowdown.

    Cooling tower blowdown.

    Treated sanitary waste effluent.

None of these streams is unique to bauxite refining.   However, it
should  be  noted  that  all of them fit very well into the total
impoundment philosophy of  disposal  of  process  wastes  from  a
bauxite refinery and would represent one increment percent to the
normal red mud load.  Effluent limitations for these streams have
not  been established inasmuch as they are not considered process
waste streams.
The characterization of process waste streams from
of bauxite is summarized in Table 11.
the  refining
                            43

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          TAEEE 11.   CHARACTERIZATION OF  PRINCIPAL WASTE STREAMS FROM U.S. BAUXITE REFINERIES
      Waste
                  Quantity
Red arud
Spent Cleaning Acid
Salts from salting -
out evaporator


Barometric condenser, C.W.*
Boiler and cooling tower
  "slowdown
Water softener sludge
Sanitary waste
500-3600 T/D  (dry basis)

  1,000-7,200 T/D (wet, settled)

  3,000-20,000 T/D  (slurry at
    18% solids)
Variable, 5-10 T/week
intermittently discharged
Variable-estimated up to
several thousand kg/day


Millions of liters/hr
Variable - thousands of
  liters/day


one to few T/D
375 liters/D/capita
          Characterization
15-20 % solids

5-12 g/1 soda

2-5 g/1 aluminum

pH - 12.5


Na2SO,, plus some free H«SO^
HC1 or HAc" may also be used

pH -  0

Na2S04 - alkaline

pH - 12.5

Temp, rise of up to 15QC(25°F)
may contain traces entrained alkali

Dilute alkaline solutions

pH -   12.5

Lime and suspended solids from
  intake water

B.O.D. 70 g((0.15 Ib)/day/capita
*C.W.= Cooling Water

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                           SECTION VI
                SELECTION OF POLLUTANT PARAMETERS
                          Introduction

The  waste  water  parameters of pollutional significance for the
bauxite refining industry include:

    Alkalinity
    PH
    Total dissolved solids
    Total suspended solids
    Sulfate

Since the waste streams are  essentially  inorganic,. biochemical
oxygen  demand  (BOD5)  and  chemical  oxygen  demand  (COD)  are
generally insignificant.  On the basis of the  evidence  reviewed
there are hazardous or potentially toxic substances in the wastes
discharged  from  bauxite  refineries.   The  use  of waste water
recycle systems, along with complete waste retention, permits the
elimination  of  the  discharge  of  all  process   waste   water
pollutants to receiving waters.

         Rationale_For_Selection of gQllutant_Paramgters

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 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
                             45

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pH  increases,  and it is advantageous to keep the pH close to 7.
This is very significant for providing safe drinking water.

Extremes of pH or rapid pH changes can exert stress conditions or
kill aquatic life outright.  Dead 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.

Since  the Bayer refining process uses a strong caustic solution,
the process waste from a bauxite refinery will be  alkaline.   As
indicated  above, the principal effluents are alkaline, with a pH
over 10.

Dissolved Solids

In  natural  waters  the  dissolved  solids  consist  mainly   of
carbonates,   chlorides,   sulfates,   phosphates,  and  possibly
nitrates of  calcium,  magnesium,  sodium,  and  potassium,  with
traces of iron, manganese and other substances.

Many  communities in the United States and in other countries use
Water supplies containing 2000 to 4000 mg/1 of  dissolved  salts,
when   no  better  water  is  available.   Such  waters  are  not
palatable, may not quench thirst, and may have a laxative  action
on  new  users.   Waters  containing more than 4000 mg/1 of total
salts are generally considered unfit for human use,  although  in
hot  climates  such  higher  salt concentrations can be tolerated
whereas  they  could  not  be  in  temperate  climates.    Waters
containing 5000 mg/1 or more are reported to be bitter and act as
bladder  and  intestinal  irritants.  It is generally agreed that
the salt concentration of good, palatable water should not exceed
500 mg/1.

Limiting concentrations of dissolved solids for fresh-water  fish
may  range  from  5,000  to 10,000 mg/1, according to species and
prior acclimatization.  Some fish are adapted to living  in  more
saline  waters,  and a few species of fresh-water forms have been
found in natural waters with a salt concentration  of  15,000  to
20,000  mg/1.   Fish  can  slowly  become  acclimatized to higher
salinities, but fish in waters of  low  salinity  cannot  survive
sudden  exposure to high salinities, such as those resulting from
discharges of oil-well brines.  Dissolved  solids  may  influence
the  toxicity  of  heavy metals and organic compounds to fish and
                             46

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other aquatic life, primarily because of the antagonistic
of hardness on metals.
effect
Waters  with total dissolved solids over 500 mg/1 have decreasing
utility as irrigation water.  At 5,000 mg/1 water has  little  or
no value for irrigation.

Dissolved  solids  in  industrial  waters  can  cause  foaming in
boilers and cause interference with cleanliness, color, or  taste
of  many  finished  products.   High contents of dissolved solids
also tend to accelerate corrosion.

Specific conductance is a measure of the  capacity  of  water  to
convey  an  electric  current.   This  property is related to the
total concentration of ionized  substances  in  water  and  water
temperature.   This  property  is frequently used as a substitute
method of quickly estimating the dissolved solids concentration.

Dissolved solids  will  be  high  in  effluents  from  a  bauxite
refining  process  and will include the alkalies sodium hydroxide
and sodium carbonate, plus sodium sulfate, sodium  aluminate  and
other  lesser  constituents  such  as  sodium chloride and sodium
oxalate.  The total dissolved solids content is an aggregation of
the components listed above and serves as an overall  monitor  of
the effluent quality.

Total Suspended Solids

Suspended  solids  include  both organic and inorganic materials.
The inorganic components  include  sand,  silt,  and  clay.   The
organic  fraction  includes  such  materials as grease, oil, tar,
animal and vegetable fats, various  fibers,  sawdust,  hair,  an4
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.
                                                              j
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.
                             47

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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
substitute  method  of  quickly  estimating  the  total suspended
solids when the concentration is relatively low.

With a closed  cycle  and  total  impoundment  of  wastes,  total
suspended solids should be low in any effluents discharged.  High
suspended  solids  content  would  indicate  a process upset or a
containment failure and is included as a significant parameter to
monitor such occurrences.
Sulfate

Sulfate concentrations in discharge streams and pH  measurements,
would  be  indicative  of  the  release  of  spent  acid cleaning
solutions.  Sulfate  is  an  undesirable  addition  to  navigable
waters.
          Rationale for Rejection of Other Waste Water
              Constituents as Pollutant Parameters
As  suggested  by  the  earlier  process  description  and by the
preceding list of pollutant parameters, the process  of  refining
bauxite  involves  earthy  inorganic  minerals.  Because of this,
several  commonly  encountered  waste  water   constituents   are
relatively unimportant as pollutants.  These are noted below.
                             48

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Biochemical Oxygen Demand (BOD)

Biochemical  oxygen  demand  (BOD)  is  a  measure  of the oxygen
consuming capabilities of organic matter.  The BOD  does  not  in
itself  cause direct harm to a water system, but it does exert an
indirect effect by depressing the oxygen content  of  the  water.
Sewage  and  other  organic  effluents  during their processes of
decomposition exert a BOD, which can have a  catastrophic  effect
on  the ecosystem by depleting the oxygen supply.  Conditions are
reached frequently where all  of  the  oxygen  is  used  and  the
continuing  decay  process causes the production of noxious gases
such as hydrogen sulfide and methane.   Water  with  a  high  BOD
indicates   the   presence  of  decomposing  organic  matter  and
subsequent high bacterial counts that  degrade  its  quality  and
potential uses.

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  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 of blood
clotting, decreased tolerance to certain toxicants, reduced  food
efficiency   and  growth  rate,  and  reduced  maximum  sustained
swimming  speed.   Fish  food  organisms  are  likewise  affected
adversely  in  conditions  with suppressed DO.  Since all aerobic
aquatic  organisms  need  a  certain  amount   of   oxygen,   the
consequences  of total lack of dissolved oxygen due to a high BOD
can kill all inhabitants of the affected area.

If a high BOD is present, the quality of  the  water  is  usually
visually  degraded  by  the presence of decomposing materials and
algae blooms due to the uptake of degraded  materials  that  form
the foodstuffs of the algal populations.

Since  the process waste streams are essentially inorganic rather
than organic, there is no significant BOD5_.

Chemical Oxygen Demand (COD)

The chemical oxygen demand in the process waste  streams  from  a
bauxite  refining  process  will  be insignificant because of the
inorganic nature of the waste.

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
exhibit 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-

                            49

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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.

Oil and grease are  not  normally  found  in  the  process  waste
streams.   The  only  source  of  oil  or  grease'  would  be from
lubrication of process machinery.   The  contribution  from  this
source is insignificant.


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 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 of the
water  increases  reaching  a  maximum at about 30^C (86%F).  The
temperature of stream water, even during  summer,  is  below  the
optimum  for pollution-associated bacteria.  Increasing the 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  under  restricted
temperature  ranges.   Spawning  may  not  occur  at  all because
temperatures are too high.  Thus, a fish population may exist  in
a  heated  area  only by continued immigration.  Disregarding the
decreased reproductive potential,  water t temperatures  need  not
reach  lethal  levels  to  decimate a species.  Temperatures that
                           50

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favor competitors, predators, parasites, and disease can  destroy
a species at levels far below those that are lethal.

Pish  food  organisms  are  altered  severely  when, temperatures
approach or  exceed  9 0%jF.   Predominant  algal  species  change,
primary  production is decreased, and bottom associated organisms
may  be  depleted  or  altered   drastically -  in   numbers   and
distribution.   Increased  water  temperatures  may cause aquatic
plant nuisances when other environmental factors are favorable.

Synergistic actions of pollutants are more severe at higher water
temperatures.  Given amounts of domestic sewage, refinery wastes,
oils,  tars,  insecticides,  detergents,  and  fertilizers   more
rapidly  deplete  oxygen in water at higher 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
preferential.  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.

Thermal economy is important to a bauxite  refining  process,  so
that  thermal  pollution is normally not significant.  When once-
through cooling is employed, temperature increases  in  receiving
waters  in  the  vicinity  of  outfalls  will be noted and may be
significant near barometric condenser discharges.   There  is  no
treatment  technology  for  heat, other than its dissipation into
some sink, either water, the ground, or the atmosphere.  For  the
purposes  of  this  document,  control consists of preventing its
dissipation into navigable waters.
                            51

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Color

Color in bauxite refining  effluents  will  usually  result  from
suspended  gangue  material  and  will  have  the  characteristic
reddish-brown color of red mud.  The  parameter  selected,   total
suspended  solids, is considered a better measure of the presence
of pollutants than color.

Turbidity

Turbidity is indirectly measured and controlled by the limitation
on suspended solids.

Trace Metals

Assuming total impoundment of red  mud,  the  hydroxides  of  the
trace  metals  associated  with the aluminum in bauxite are quite
insoluble and should not  leach  from  a  properly  designed  and
operated impoundment area.
                              52

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                           SECTION VII
                CONTROL AND TREATMENT TECHNOLOGY
                          Introduction

The control and treatment technologies for the waste streams of a
bauxite  refinery  must  be  viewed  in  light  of   the   unique
circumstances  applicable  to this specific industry subcategory.
The key factor is that bauxite refineries are  hydrometallurgical
plants   producing   enormous   tonnages   of  an  aqueous  waste
suspension.  As illustrated in Table 11, these range from U54  to
3,265  kkg  (500  to 3,600 ton)/day on a dry basis.  On a settled
mud basis these qualities approximately double.  In terms of  the
slurry  issuing  from the process at 15 to 20 percent solids, the
tonnages can exceed 18,140 kkg (20,000  ton)/day.   There  is  no
practicable   or   currently   available   treatment  or  control
technology for such a waste except impoundment.  Thus, as a basic
operating premise, a bauxite refinery must provide a large  diked
area for impounding the red mud produced.  This has been the case
for all but two plants.

Construction  of  this  large diked area creates the most logical
and cost effective receptacle for  impounding  all  other  liquid
wastes,  associated  with the refining process.  The red mud lake,
as a recipient of the red mud and all other liquid wastes, offers
a practicable and currently available technology to  achieve  the
goals of the Act.

The  nature  of  the other pollutants from a bauxite refinery, as
described and discussed in Sections  V  and  VI,  are  such  that
treatment  is  not  a  particularly viable option.  These process
wastes are characterized by the objectionable characteristics  of
alkalinity, acidity, and dissolved solids.

The   first   two   characteristics  can  be  neutralized,  which
transforms them into the third  objectionable  pollutant.   Thus,
the  available  facts  lead  to  the  conclusion that the optimum
solution for treatment and control of all other  pollutants  from
bauxite  refining is impoundment in the red mud lake system.  The
technology is currently available and practicable.

It has generally been recognized by the bauxite refining industry
that impoundment of the gangue from bauxite ore is feasible,  and
the  refinery  water  circuit  can  operate either as a closed or
nearly  closed  circuit*   Accordingly,  most  plants   currently
impound  at  least  the mud wastes, and, in many instances,  other
significant process waste streams.

There may be additional  nonprocess  streams,  such  as  sanitary
effluents  and  boiler and cooling tower  blowdowns  which must be
disposed of.  These lesser streams may or may not be included  in
                            53

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the  total impoundment site.  In more arid climates, the tendency
is to totally impound all streams; in high rainfall regions,  the
tendency is to discharge.

The  parameters  in  the  water  circuit that inhibit adoption of
total recycle of all streams  (no discharge) are dissolved solids,
and in some instances, heat.  The precipitation step is  the  key
to purity of alumina product and the efficiency of the operation.
The  effects  of  buildup of contaminants in process water do not
appear to be completly defined or fully understood, and may  well
be significantly influenced by other variables.  In any event, it
appears  that  there  is  a  tendency  to  bar contaminants whose
behaviors are not understood, so that they will be discharged  in
preference  to  recycling  to  the  process stream as a part of a
total impoundment scheme.

The other problem  is  heat.   The  cooler  the  water  the  less
treatment  is  needed  and  the easier it is to achieve a desired
vacuum on a barometric condenser.   Heat  rejection  may  not  be
sufficient  in  a closed-loop lake system to provide for adequate
cooling of barometric condenser effluents for reuse.  Hence, some
of  these  systems  will  use  once-through  cooling  water  when
available  in  a satisfactory quantity and quality.  Alternatives
are cooling towers or much larger lakes.
The state of the art control technology can be best described  in
terms  of  the  individual  types  of waste streams.  The red mud
stream must be impounded.  Other alternatives  are  possible  for
the  other  waste  streams.  Due to the nature of the pollutants,
primarily dissolved solids not readily  precipitated,  there  are
essentially  no  end-o'f-the-pipe  pollution abatement schemes for
these other bauxite process wastes.  Some treatment  technologies
are described in the following paragraphs.
The only practicable control technology for the enormous tonnages
of  muds  produced by bauxite refineries each day is impoundment.
Muds are impounded in large diked lakes, which may range in  size
from 40 ha (100 ac) to as much as 800 ha (2000 ac) .

Two approaches are used for construction of mud lakes.  The dikes
are erected to their full height initially.  The complete lake is
available from the beginning, and additional dike construction is
not  required  during  the life of the lake.  The construction of
this kind of dike has been  described  by  Rushing,    (8)   and  is
summarized below.
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The installation described contained two mud  lakes containing  4.8
and 3.3 square kilometers  (1200 and 800 acres) and represents  the
largest  such  lakes in the bauxite refining  industry,  while  the
dike construction is generally typical, it was modified  slightly
because  of  some  local  considerations.  The top layer of soil,
about 25-30 cm  (9-12 inches) was highly weathered, and was removed
before construction of the dikes.  The 25-30  cm  below  this   was
scarified  and  compacted  to form the dike foundation.  A trench
was excavated around the entire  perimeter  of  the  lakes  3-4.5
meters (10-15 feet) deep and 2.5-3 meters  (7.5-9 feet) wide.   The
trench  was  backfilled with clay and compacted in 15 cm  (6 inch)
layers as the dike was built.  This feature helps to key the dike
to minimize seepage of lake water.  Details of  the  construction
are  shown  in Figure 7.  Embankments were laid out for a maximum
height of 9 meters (30 feet) due to  the  somewhat  poor  bearing
soils.   Slopes  of  the  dikes  were  lower  (1:4 outside and  1:3
inside)  than often used due apparently to local conditions.    One
other  construction  feature  peculiar  to  the  location was  the
facing of the dike nearest the bay with riprap  to  protect  from
hurricane  tide and wave action.  Pipe was laid on the top of  the
dikes with mechanical sections to allow  for  expansion  movement
and  ease in breaking the sections apart to modify the pipe line.
Several pipes also were routed to the center  of the storage areas
so that the mud could be distributed more  evenly.   The  initial
capital   investment   is   higher   for   this  method  of  dike
construction, but maintenance and operating costs will be lower.

In the other,  "low  capital  investment-high  maintenance  cost"
approach,  a  low  dike is initially built,   which is continually
raised as the lake fills.  The construction of this type of  dike
is   outlined   schematically  in  Figure  7.   Initially  a   low
combination roadway-dike is constructed to a  height  of  1.2-1.8
meters (4-6 feet)  and with a width of 4.5-5.3 meters  (15-18 feet)
from  some stable sand-clay mixture.  Along the inside perimeter,
steel  standards  are  erected,  from  which  the  mud  pipe   zs
suspended.   The  pipe  has  a tapered bottom shape, in which  th^e
coarser sands settle out.  At intervals the tapered  bottoms   are
valved;   attached  hoses are used to convey the sand to form sand
dunes, with a gently sloping beach  towards   the  inside  of   the
lake.   To  avoid  erosion  of the beach, the main flow of mud is
diverted well out into the lake.   As  the  height  of  the  dike
approaches  the  original  pipe  line,   a new set of standards is
erected inside and the pipe lines relocated.

The success of this type of dike construction  depends  upon   the
existence  of  a coarse sand fraction in the red mud.  Thus, this
is practicable for Surinam bauxite,  but  less  so  for  Jamaican
bauxite.    The net disposal costs appear to be comparable for  the
two approaches.

It is possible to raise the dike around a mud lake in stages by a
variation of the above technique.  With the usage of a drag line,
previously settled and well-consolidated red mud can  be  dredged
from  the  lake and cast on the bank to raise it in 2.5 meter  (8-
foot)  increments.   Slopes must be low and there is a  significant
                            55

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    Inside slope
                      Dike Key
                    3-4,5 m deep
                    2.5m min.width
                             a. Initial Full Dike Construction
                                      Phase TL relocation
                                       of mud line
Phasen dike
                                               Mud line-Phase I
                                                           Phase X dike
                                                                     Roadway
                                                                       4,5-6m wide
                                                                              high
                         b. Buildup Construction of Mud Lake Dike
                       Figure 7.  Mjd lake dike construction.
                                       56

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diversion  of  lake  capacity  to  dikes.   This technique can be
applied even to Jamaican  red  mud,  in  spite  of  its  nonsandy
character.

Disposal of Jamaican red mud can pose special problems, resulting
from  its  very  small  particle  size  and  somewhat thixotropic
character.  Its settling properties are  poor.   For  example,  a
maximum  compaction  of  about  35  percent solids is possible if
settling and compaction occur below a layer  of  water  (8).   If
Jamaican mud can be spread in layers only inches deep rather than
feet,  and  exposed  to  net  evaporation conditions, it will dry
satisfactorily.  Once past a critical moisture content (i.e., the
60 percent solids range), the mud does not resuspend when  wetted
(8).   However, adoption of this approach to the disposal of mud,
like Jamaican red mud, depends upon the existence of a relatively
arid climate, and the availability of large tracts  of  land  for
the  disposal  area.  Where land is unavailable and rainfalls are
high, this approach may not be practicable.
                                       dewatering of Jamaican red
                                       that  the  solids  content
                                      Approximately 40 percent of
                                      clear  effluent  containing
                                       for  recycle to the plant.
Another  approach  may  be  required  in  nonarid  regions.   One
alternative, investigated at the U.S. Bureau of Mines by Good and
Fursman  (13),  utilized  centrifugal
mud.  Results of this study indicated
could  be  increased  to 40 percent.
the slurry liquid was recovered as a
dissolved  alumina  and  soda  values
Economic analysis indicated that centrifugation  and  evaporation
of  the  filtrate for recovery of the alumina and soda values was
approximately a "break-even" operation.  With this arrangement, a
satisfactory consolidation and dewatering of Jamaican red mud  is
achieved,  even  in a region where the annual evaporation is less
than the annual rainfall.  The net positive water  balance  makes
the  management  of  the  water  circuit  more  difficult and may
require  increased  evaporator  capacity,  but  the  circuit   is
controllable.

In  all  mud lake construction, care must be taken to insure that
the bottom is as impervious as possible.  Soil tests may be  made
to evaluate the bottom, and clay may be brought in for the bottom
if  an  undesirable  porosity  is  indicated.   Depending  on the
structural characteristics of the underlying soil, the  dike  may
also  be  keyed-in  by  excavating a trench along its center line
before construction.  Dikes were  frequently  built  with  a  1:1
slope;  after  some  trouble  with dike slippages and failures, a
slope of 1:2 or less is now more common.

Dike heights will  depend  upon  soil  and  mud  characteristics.
Heights of 6-9 meters (20-30 feet)  are usual with good underlying
soil  conditions  and a mud which sets up.  Arkansas dikes can be
as high as 18 meters (60 ft).  Typically,  a  refinery  initially
constructs  a  mud  lake of 20-40 ha (50-100 ac), surrounded by a
dike on four sides.  After this lake is  filled,   a  new  one  is
constructed  adjacent to it.  By using one side as a common dike,
only three new sides need to be constructed, thus,  reducing  the
capital investment.
                           57

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Mud  lakes  are  not single-purpose operations, nor is their cost
entirely assignable to pollution control.  They are,  of  course,
primarily  employed  as  receptacles  for the waste mud residues.
Secondary uses include cooling ponds  and  water  reservoirs,  as
well as receptacles for other minor waste streams from the plant,
such  as  boiler and cooling tower blowdowns and treated sanitary
waste effluents.  If  soda  concentrations  are  not  excessively
high,  they  can  also  serve to some extent as an additional mud
washing stage.  Thus, for the purpose of this report, the red mud
lake may be considered  as  the  major  feature  of  the  bauxite
refinery.   The intrinsic requirement for the disposal of the red
mud residue from alumina plants has  inherent  effects  on  plant
space  requirements ,  plant  site  arrangement,  and  the initial
design of the plant water system.

Spent cleaning .Acid,  spent  cleaning  acid  from  cleaning  heat
exchange  surfaces,  filter  cloths,  etc., consists of solutions
containing high dissolved solids  concentrations.   One  producer
neutralizes  the  spent  acid  with mud before discharging to the
river.  Another producer  is  using  an  improved  method,  which
involves  the  reaction  of the spent cleaning acid with lime and
forming insoluble calcium sulfate, which is then disposed  of  in
the red mud lake.  Several other producers achieve neutralization
by  conveying  the  spent  acid  to  a  red  mud lake where it is
neutralized by alkaline mud slurry.  Some use  an  abandoned  mud
lake  to  eliminate any possibility of sulfate buildup in the red
mud lake circuit; others use an active lake and find that  enough
sulfate  is  trapped  by  the  settling  mud  to prevent  sulfate
buildup in the water circuit.

Using readily available technology, the spent cleaning acid could
be neutralized to form an insoluble salt, evaporated to  dryness,
and  disposed of to a landfill.  If it were not for the existence
of the alternative red mud  lake  "sink",  this  would  no  doubt
constitute the recommended treatment technology.

 al£s_ _ from  Salting-Out __ Eyapo?:atgr-
                                       Where dissolved impurities
must be removed from the caustic  liquor  circuit  of  a  bauxite
refinery  to  prevent accumulation to levels causing interference
with satisfactory operations, a salting-out evaporator is used on
spent liquor returning to the digesters from  the  precipitators.
By  greatly  concentrating  the  liquor,  the solubilities of the
contaminants are exceeded and they  crystallize  out.   Principal
components  are  sulfates,  and sodium oxalate resulting from the
traces of humic acid in the bauxite feed material.
      V

One control technology is to dispose of the solid  product  to  a
landfill,  with  the  waste  being  covered  with soil to prevent
leaching.  Another technology, mentioned in an  earlier  section,
avoids  the  problem  by promoting the adsorption of contaminants
upon the red. mud  prior  to  its  separation  from  the  pregnant
bauxite  slurry.  However, this technology may be applicable only
to Surinam bauxite.

-------
Perhaps  the  simplest  control  technology,  adopted  by several
producers, is the obvious one of disposal by  impoundment  in  an
abandoned red mud lake.

Barometric  Condenser  Cooling  Water. This water comes under the
heading of process water, because it comes  into  direct  contact
with  process reactants.  As noted earlier, very large quantities
of water are used to provide the reduced  pressure  in  the  last
stages  of  flash  evaporators  or  multiple-effect  evaporators.
Because this condenser water is used in such high volume and  the
carry-over  of  alkali to it is small, it is sometimes discharged
to surface waters without treatment.   Two  plants,  (G  and  H),
employ  this  procedure for discharge of all barometric condenser
effluents.  Another plant,  (B), recycles the barometric condenser
effluents from the green liquor flash evaporators to the  process
lake,   but   discharges   the   effluents  from  the  barometric
condensers,  operating   on   the   spent   liquor   multi-effect
evaporators,  to  an  adjacent  bay.   In  all  three  cases, the
receiving body of water is  very  large,  with  a  large  thermal
capacity.

It  must  be  recognized  that waste heat, if not rejected to the
water phase of the environment, must be rejected  either  to  the
earth  or to atmosphere, and the latter is the more favored sink.
The best technology available to dissipate heat to the atmosphere
is evaporative cooling, and this technology is applied in several
forms such as cooling ponds and cooling towers.  In  both  cases,
the  water  circuit is closed (except for blowdown) and the water
is recycled for reuse.  The simplest application is the use of  a
cooling pond or lake sufficiently large for the heat to dissipate
to the atmosphere by evaporative cooling.

Cooling towers, both mechanical draft and natural convection, are
also  widely  used,  and  would be considered as best practicable
control technology currently available.  Such technology does not
require  the  large  land  area  necessary  for  surface  cooling
systems,  normally  an  advantage,  but not necessarily one for a
bauxite refinery, which requires a  large  pond  area  for  other
reasons.   Thus,  while  cooling towers are normally economically
competitive with evaporative cooling in ponds, towers may not  be
an individual option in selecting a cooling method.

When the barometric condensers are operated in closed circuit, as
described  above,  the problem of potential alkaline Carryover is
taken care of, since any carryover is retained in the circuit.

Cooling Tower and Boiler Blowdown.  Blowdown from a cooling tower
associated  with  process  barometric  condensers  constitutes  a
process waste.  Since the contained pollutants are soluble salts,
no  simple and practicable precipitation technique is applicable.
The blowdown could be evaporated to a solid state,  suitable  for
landfill  disposal.   Reverse  osmosis  could  be  applied  as  a
pretreatment to recover a pure water stream.  Although the result
would be  discharge  of  pollutants,  reverse  osmosis  would  be
significantly  more  expensive  than direct disposal to a red mud

                            59

-------
lake.  However, the best practicable control technology currently
available  consists  of  impoundment  of  this waste stream in an
available red  mud  or  process  lake,  which  also  achieves  no
discharge,of pollutants to surface waters.

Blowdown from boilers and from associated cooling towers does not
constitute   a   process   waste  stream.   Effluent  limitations
guidelines and standards of performance for such streams will  be
developed in the near future.

Clean-Up Waste Streams.    Hose-down  and  other  clean-up  waste
streams are ubiquitous  at  a  bauxite  refinery.   They  contain
suspended  bauxite solids and pollutants found in bauxite liquor.
These waste streams are low in alkalinity, but dilute.  The  best
practicable  control technology currently available is to recycle
such wastes to the process, with the  optimum  point  of  recycle
being  the  red  mud  lake.   In a plant not operating on a water
deficiency basis, economical  usage  of  hose-  down  water  will
minimize  the water management problems associated with excessive
accumulation of water in the process water circuit.
Sanitary._Wa_ste s.  Sanitary wastes are not
wastes from bauxite refineries.
considered  as  process
The  application  of  the  best  practicable  control  technology
currently available to  process  waste  streams  of  the  bauxite
refining process is summarized in Table 12.
         S t at us_aiid_Pians .

The  bauxite  refining industry has begun to reduce the discharge
of pollutants, and further reductions are planned.   The  present
industry  status  and  reported plans are summarized in Table 13.
Exemplary plants, with no  discharge  of  pollutants  to  surface
waters, are plants C and E.

Total Impoundment Management .

The  mud  lake  is  the  central  item  in  any total impoundment
management scheme.  It is used for the alkaline  mud  stream  and
possibly  for  one  or more of the other waste streams previously
discussed.  There is variability in the manner  of  handling  the
ancillary waste streams.  They may also be disposed of in the mud
lake  or  in other similar clear water or storm water reservoirs.
The requirements for the  recycling  of  the  other  streams  are
flexible,  so  that  optional  solutions are possible.  This also
includes the recycling of barometric condenser cooling water.

An important item in a total impoundment scheme is management  of
general aqueous wastes from the refinery.  A well designed system
will include concrete curbs around all process areas where spills
or  leaks  of  process  solutions  could  occur,  with the drains
connected to a collection system.  Ultimate disposal will  be  to
the  red  mud lake or one of the other lakes in the total recycle
circuit.  Some trouble has been  encountered  in  the  past  from
                           60

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           TABLE 12.,   SUMMARY OF EFFLUENT REDUCTIONS ACHIEVED FOR BAUXITE REFINERY
                       PROCESS WASTES USING BEST PRACTICABLE TECHNOLOGY CURRENTLY
                       AVAILABLE
     Waste Stream
    Parameters
  Best Practicable(Level I)
Technology Currently Available
     Effluent
Reduction Achieved
 Red Mud
 Spent Cleaning Acid
 Barometric condenser
 cooling water

 Barometric condenser
 C.T. blowdown

*lHose-downtf and clean-up
 streams
TSS, TDS, Alkalinity
TDS, Sulfates, pH

TDS, sulfates, alka-
linity

Tlfe, Heat, alka-
linity
TSSj TDS, alka-
linity
 Impound and recycles aqueous
 phase; concentrate if nec-
 essary (A,B,C,D,E,F,I)

 Impound in red mud lake
 (B,C,D,E,Ff)
 Impound in red mudJlake
 or landfill (C,E)

 Cool and recycle
 (1/2B,C,D,E,1/2F)

 Impound in red mud lake
 (B,C,D,E)

 Recycle to process
 (Insufficient data)
   No discharge



   No discharge

   No discharge


   No discharge


   No discharge


   No discharge

-------
                         TABLE 13    HATER POLLUTION ABATEMENT STATUS AND PLANNED CHANGES
                                   (PROCESS AND NON-PROCESS WASTE STREAMS)
Plant
                                                                                 Disposition
Waste Stream
Parameter
    Present Status
Planned Changes
  A     Red mud

        Spent cleaning acid


        Salts from evaporator
        Barometric condenser
          C.W.

        Boiler and C,T. blow-
         ' down
  10
        Hose-down
                        TSS, TDS, alkalinity

                        TDS, sulfates, pH
                        TDS, sulfates, alkalinity,
                        oxalate

                        TSD, beat
                        TDS
        Compressor-after cooler    Heat
                        TDS, TSS, alkalinity
        Water softener sludge      TSS, alkalinity
        Sanitary waste
                        BOD
                                                No change planned

                                                Neutralize with lime and
                                                to abandoned red mud lake
To red mid lake

Discharged to river
                      No salting-out evapora-
                      tor

                      No barometric condenser
                        used
                      Boiler blowdown to river; No change planned
                        no cooling tower

                      Once-through non-contact  Install cooling tower and
                        discharged to river       close cycle

                      No data (return to cir-   No data (recycle?)
                        cult?)
                      No softener; potable             	
                        water obtained from
                        city

                      Untreated; discharged to  To be connected to city
                        river                     sewerage system

-------
                                                 TftBIE 13.  (continued)t
Plant
                                                                                  Disposition
Waste -Stream
Parameter
                                                                  Present Status
Planned Changes
B     Red mud
          *

      Spent cleaning acid

      Salts from evaporator
        Barometric condenser
          C.W. "
      Boiler and C.T. blow-
        down
 w
                       TSS, TDS, alkalinity

                       TDS, sulfate, pH

                       IDS, sulfates, alkalinity,
                       oxalate

                       T0S; heat
        Compressor after-
          cooler

        Hose»down

        Sanitary wastes
                       IDS



                       Heat


                       TSS, TDS, alkalinity

                       BOD
                                                               To  red mud lake

                                                                To abandoned red mud lake

                                                                No salting-out evaporator
                      Flash evaporator condensers
                        C,W. to process lake;
                        spent liquor evaporator
                        condenser C.U. discharged
                        to bay

                      Boiler blowdown to storm
                        water lake; no cooling
                        towers

                      To lake system; return to
                        circuit

                      Mo data

                      Secondary treated effluent
                        to lake system
                                                    No change planned

                                                    No change planned
                                                                                              No change planned
                                                                                              No change planned
                                                                                            No change planned


                                                                                            To lake system (?)

                                                                                            No change planned
  C     Red mud

        Spent cleaning acid


        Salts from evaporator
        Barometric condenser
          C.W.
                       TSS, TDS, alkalinity

                       TDS, sulfates, pH
                       TDS, sulfates,. alkalinity,
                         oxalate

                       TDS, heat
                      To brown mud lake

                      Neutralized and to brown
                        mud lake

                      Evaporator to dryness and
                        to covered landfill

                      To clear lake; recycled
                        to process
                                                                                            No change planned

                                                                                            No change planned


                                                                                            No change planned


                                                                                            No change planned

-------
                                                  TAE3JE 13. (continued)
                                                                                   Disposition
Plant
     Waste Stream
Parameter
Present Status
Planned Changes
  C (coat Mt)

        Boiler and C.T. blowdown   TDS

                                   Heat
Compressor
  after-cooler

Hose-down

Sanitary waste
                                   TDS, TSS, alkalinity

                                   BOP
                     To lake system; recycled

                     To lake system; recycled
                          No change planned

                          No change planned
                     No date (to lake system??)    To lake system (?)

                     To lake system                No change planned
        Red mud

        Spent cleaning acid

        Salts from evaporator
        Barometric condenser
          C.tf.
        Boiler and C.T. blow*
          down
        Hose-down

        Sanitary wastes
                           TSS, TDS, alkalinity

                           TDS, sulfates, pH
                     To brown mud lake

                     To brown mud lake
                           TDS, sulfates, alkalinity,   No data (not separated ?)
                             oxalate
                           TDS, heat
                           TDS
        Compressor after-cooler    Heat
                           TDS, alkalinity

                           BOD
                     Flash evaporator C.W.  to
                       mud lake; spent liquor
                       evaporator C.W,  to C.T.
                       in closed circuit

                     Boiler blowdown to lake; no
                       C.T. blowdown-intermittent
                       cleanout

                     Once-through non-contact,
                       discharged to river

                     No data

                     To mud lake
                          No change planned

                          No change planned

                          No data


                          No change planned




                          No change planned



                          No change planned


                          No data

                          No change planned

-------
                                                     TABt£ 13.  (continued)
  Plant
                                                                                     Disposition
     Waste Stream
      Parameter
   Present Status
   Planned Changes
in
Red mud
   *

Spent cleaning acid

Salts from evaporator


Barometric condenser
 C.W.

Boiler and C.T. blow-
  down

Compressor after-cooler

Hose-down

Sanitary wastes
                                     TSS, TDS, alkalinity

                                     TDS, sulfates, pH
                             To red mud lake

                             To red mud lake
                                     TDS, sulfates, alkalinity,   Calcined with soda ash
                                       oxalate                      and bauxite and leached
TDS, heat


TDS


Heat

TDS, alkalinity

BOD
                                                                  To C.T. in closed circuit;
                                                                     recycled
                              No change planned

                              No change planned

                              No change planned


                              No change planned
                                                                  To process water reservoir    No change planned
To C.T. in closed circuit

No data

Secondary treated effluent
  to process reservoir
No change planned

No data

No change planned
           Red mud

           Spent  cleaning acid

           Salts  from evaporator

           Barometric condenser
             C.W.
           Boiler and C.T.  blow-
             down
                           TSS, TDS, alkalinity

                           TDS, sulfates, pH

                           TDS, sulfates, alkalinity

                           TDS, heat



                           TDS
                             To red mud lake

                             To red mud lake

                             No salting-out evaporator

                             To red mud lake; recycled
                             Summertime-use once-thru;
                               to river

                             Discharged to river
                              No change, planned

                              No change planned

                              No change planned

                              No change planned



                              No change planned

-------
                                               T3VBLE 13.  (continued)
                                                                                    Disposition
Plant
Waste Stream
Parameter
Present Status
Planned Changes
  F     Compressor after-cooler
(cont'd)

        Hose-down

        Water softener sludge

        Sanitary wastes
                       Heat


                       TDS, alkalinity

                       TSS, alkalinity

                       BOD
                        Once-through; non-contact,
                          discharged to river

                        No data

                        Discharged to river

                        Secondary treated effluent
                          discharged to^riyer	
                          No change planned


                          No data

                          No change planned

                          No change-'planned
  ot
        Red mud
        Spent cleaning acid
        Salts from evaporator
        Barometric condenser
          C.W.
                       TSS, TDS, alkalinity
                       XDS, sulfates, pH
                       TDS, sulfates, alkalinity,
                        oxalate

                       TDS, Heat
        Compressor after-cooler    Heat
        Hose-down

        Sanitary wastes
                       TDS, TSS, alkalinity,

                       BOD
                        Discharged untreated to
                          river

                        No data (discharged to
                          river ?)

                        No salting-out evaporator
                        Once-through river water;
                          discharged to river

                        Once-through,non-contact,
                          discharged to river

                        No data

                        Secondary treated effluent
                          discharged to river
                          Solids  to red mud  lake;
                            portion of supernate
                            nautralized and  dis-
                            charged to river.
                          No data
                          No change planned
                          Neutralize before
                            discharged to river

                          No change planned
                          Recycled to process

                          No change

-------
                                             TRBEE 13,  Continued)
                                                                                  Disposition
Plant
Waste Stream
Parameter
Present Status
Planned Changes
  H     Red mud




        Spent cleaning acid

        Salts from evaporator
        Barometric condense'"
          C.W.

        Boiler and C.T. blow-
          down
        Hose-down

        'Water softener sludge

        Sanitary wastes
                      TSS, TDS, alkalinity
                      TDS, sulfates, pH

                      TDS, sulfates, alka-
                        linity, oxolate

                      TDS, heat
                      TDS
        Compressor after-cooler    Heat
                      TDS, TriS, alkalinity

                      TSS,. alkalinity

                      BOD
                         Discharged untreated to
                           river
                         No data

                         No salting-out evaporator
                         Once-through river water;
                           discharged to river

                         Discharged to river
                         Once-through, non-contact,
                           discharged to river

                         No data

                         Discharge to river

                         Secondary treated effluent
                           discharged to river
                           Solids to red mud lake;
                             portion of supernafe
                             neutralized and die-
                             charged to river

                           No data

                           No change planned
                           Neutralize before d!0<
                             charged to river

                           No change
                           No change


                           Recycled to process

                           No change

                           Improve plant

-------
                                                     1BBIE 13.  (continued)
   Plant
    Waste Stream
                                                                                      Disposition
Parameter
Present Status
Planned Changes
a\
CO
Red mud


Water softener sludge



Spent cleaning acid


Salts from evaporator


Barometric condenser, C.W,


Boiler and C.T. blowdown


Compressor after-cooler


Hose-down


Sanitary wastes
                                       TSS,  TDS,  alkalinity


                                       TDS,  TSS
                         To red mud lake


                         Ocean water desalinated;
                           reject stream returned
                           to ocean             «\
                           No data


                           No data
                                                                                                 No data

-------
failure  to  install  curbs,  or  from cracks and crevices  in  the
concrete floor slab which permitted escape  of  alkaline  process
solutions.  Most refineries have campaigns currently under  way to
eliminate  these  sources  of effluents, and are expected to have
them eliminated before July 1,  1977.

Another factor in a total impoundment scheme is whether the plant
is located in  an  area  of  net  rainfall  or  evaporation.   As
described  in section IV  (Table 4) , two refineries are located in
areas where  average  annual  evaporation  substantially  exceeds
average  annual  rainfall.   The other six refineries, located in
the  continental  U. S. ,  are  in  areas  of  net   excess   water
accumulation, with annual averages ranging from about 10 to 40 cm
(4-16  in) .   This  complicates  the water management scheme.  It
does not necessarily follow that a  refinery,  so  located,  must
expend energy evaporating rainfall.  The bauxite refining process
intrinsically has a substantial negative water balance, which  has
to  be  supplied  by  either  fresh  water  intake  (purchased or
otherwise, acquired)  in rainfall- deficient areas, or is  supplied
by the rainfall (in rainfall excess areas) .

The  negative  refinery  water  balance arises from the fact that
dried bauxite ore, is converted  to  anhydrous  alumina  product,
with  the  water  of  hydratipn  being  eliminated in the alumina
calcining kilns.  The gangue material (red mud)  is  removed from
the  process as a wet mud containing at least 50 % moisture.  Much
water is recovered as high-purity condensate from the flash tanks
and added to the net positive rainfall accumulation,  assuming  a
minimum  red  mud  lake collection area.  The generalized example
described below is based on the following basic assumptions;
    Plant capacity is 3,000  ton/day  calcined  alumina  product,
    Jamaican bauxite, dried = negligible free water;

    49%  A1202*3H20, 100%  extraction efficiency  (losses of Al to
    mud neglected)";

    1 ton (dry)  mud/ton A1203 product;

    CCD thickener and washer underflow = 2036 solids;

    10 Ibs H20/lb, dry mud for washing; recycled water  from  mud
    lake, supplemented by makeup water;

    Mud lake water: 5 g/1 soda; 2.5 g/1 aluminum;

    1  Ib H20/lb A1203 final wash of product, using condensate or
    makeup water; eliminated in spent liquor evaporator;

    Mud lake = 162 ha (400 ac) ;

    Plant location gulf south,  with net excess of  rainfall  over
    evaporation  =  9  in/yr  (e.g.. New Orleans locations (Table
                           69

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With the 3000 tons of recoverable alumina in  the  bauxite  feed,
there  are,  1590 ton/day of combined water of hydration.  This is
one of the key masses of  water  removed  from  the  process;  it
passes  up  the  stack  to  the  atmosphere  when  the product is
calcined.

As described in earlier sections, there are tremendous  flows  of
water   in  internal  circuits  within  the  plant.   Very  large
quantities of steam are used for heating, but nearly all  of  the
contained  heat is recovered and the condensate reused throughout
the plant,  similarly, there are  tremendous  flows  through  the
barometric   condenser  circuit.   There  are  additions  to  and
blowdowns from these circuits/ but for this generalizied example,
it can be assumed that they are in nominal balance.

The other significant water withdrawal mechanism is the red  mud.
The  underflow  from  the last washing thickener will approximate
15,000 ton/day, at 20X solids.  Of the 12,000 tons of water going
with 3,000 ton/day of mud to the red mud lake, only 7500  ton/day
return  to  the process; the remaining 4,500 tons is tied up with
the mud  at  the  bottom  of  the  lake.   In  total,  these  two
mechanisms  represent  a  removal  of water from the hypothetical
circuit of 6090 ton/day.

Rainfall is the only uncontrolled water input to the circuit.  At
the location  of  the  example  plant,  the  net  average  annual
rainfall gain is 9-in/yr (Table 4).  For the asaumed 400-acre red
mud   lake,   this  represents  407,720  ton/yr,  an  average  of
approximately 1120 ton/day.  Overall system  deficiency  is  then
4970  ton/day,  as illustrated by the schematic diagram in Figure
8.

This estimate should be regarded as an approximation, so that not
all of the deficiency represents discretionary  applications  for
the  introduction  of makeup water into the system.  However, one
comparable plant,  operating  with  a  closed  circuit  which  is
located  in  a  more  arid  area of the Gulf Coast, has an actual
water makeup requirement of this magnitude.

In spite of the approximate nature of the  calculations  of  this
generalized  example,  it is apparent that even in an area of net
excess rainfall, it should not be necessary to  distill  rain  in
order to close the water circuit of a bauxite refinery.  There is
a  sufficiently large difference between water inputs and outputs
to the cycle, that with careful water circuit  management,  there
should  exist  a  net  deficiency,  which  can  be satisfied on a
discretionary basis.

Closing the water circuit will tend to increase  the  buildup  of
soluble  contaminants,  making the incorporation of a salting-out
evaporator into the spent  liquor  circuit  necessary.   However,
there  are also some monetary advantages which offset closing the
circuit, such as elimination of losses of the  soluble  soda  and
aluminum  associated  with  the  red mud slurry.  For the subject
example, the 12,000 ton/day of red mud liquor leaving  the  plant
                            70

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.
Combined HgO From Calciner
1590 T/D
Makeup Water
Bauxite
4590 T/D
A12O3 • SHgO
( - 3000 T/D AlgOg)
Condensate
t 1
Steam 1
f Bauxite J
v Refinery °j
i
Bar Cond
T c. w.
WATER BALANCE
IN
Rainfall, ave. 1120 T/D
TOTAL IN 1120
Deficiency = 4970
Supernate
8620 T/D
Red Mud Slurry
( 3000 T/D Mud ^
( 12000 T/D HO
ti
Net Rainfall
Accumulation
1120 T/D (Ave. )

400 Acre
Lake
/ S/ / SS///SS/' '// /
//{ 3000 T/D Mud 40°/o ///
// \ 4500 T/D HgO Solids XX/
' / / ////S/S///SS ///
OUT
Combined HO 1590 T/D
ii
Settled Red Mud 4500
Total OUT 6090 T/D
Figure 8.  Generalized diagram of basic water balance for a
           3000 T/D bauxite refinery processing Jamaican bauxite,

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carries  approximately  60  ton/day  of  soda  and  56 ton/day of
alumina.  Closing the circuit returns 7500 ton/day of supernatant
to the plant, and recovers about 37.5  ton/day  of  soda  and  35
ton/day of alumina.

In  summary, 9current  state  of the art technology is to totally
recycle all process waters  and  to  impound  all  solid  process
wastes.   Two  plants  are routinely doing this.  Five others are
totally impounding the red mud, as well as part or all of various
other smaller streams.
Storm Water Management.
                                                               of
                                                               no
Most bauxite refineries have successfully solved the  problem
providing  for  total  impoundment  of  process  wastes (i.e.,
discharge of process waste water  pollutants).    The  problem  is
defined  and  understood,  and  the  technology  is  available to
implement the effluent limitations.
Storm water management is not so clearly defined.   The  position
generally  held  in the industry is that some quantities of storm
water runoff from plant sites  can  be  subjected  to  management
controls,  but that an upper limit needs to be established, above
which, management (and collection)  of storm  water  need  not  be
attempted.     Present    technology   (and   that   in   planned
installations) is based on designing  a  collection  and  storage
system  which  will  handle an average (not torrential) rainfall,
but limitations on maximum flows are achieved by sizing pumps and
piping in storm water systems or designing  weirs  at  collection
points which will divert flows above a predetermined maximum.

As  evidenced  by  some  of  the rainfalls which can occur in the
areas in which bauxite refineries are located (see Table 4),  the
total  collection  and  retention  of  all  rainfall  may  not be
technically  or  economically   practicable.    The   promulgated
regulations   provide   provisions  for  the  discharge  of  such
rainfall.
                             72

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                          SECTION VIII
           COST, ENERGY* AND NQNHATER QUALITY ASPECTS
                          Introduction
In  this  section,  costs  associated with the degree of effluent
reduction that can be achieved by exemplary treatment methods are
summarized.  The nonwater quality aspects of solid waste disposal
and the energy  impact  of  the  in - process  control  and  waste
treatment technologies are also discussed.

As  noted  in  Section  V,  the  pollutants  found in waste water
effluents from bauxite  refining  are  characteristically  either
highly  soluble,  nonprecipitable,  dissolved salts, or suspended
solids (i.e., not amenable to end-of-pipe treatment  technology).
Thus,  the only practicable treatment method for bauxite refining
wastes is total impoundment, and the degree of effluent reduction
achieved by impoundment is the total elimination of the discharge
of process waste water pollutants to navigable waters.

                   Treatment and Control Costs

Although certain process  credits  undoubtedly  derive  from  the
quasi-washing stage, the costs of impoundment in the red mud lake
and  total  recycle  are  considered  wholly as pollutant control
costs.  Also, in the absence of a closed water cycle,  additional
sources of water intake would be required at some cost.  However,
the   credits  from  the  additional  washing  are  difficult  to
estimate,  and  the  water  cost  savings  are  highly  location-
dependent.

The  capital  cost of an impoundment and recycle system contains,
in its simplest form the following major cost elements:

    (a)   Cost of land.
    (b)   Cost of construction of reservoir(s).
    (c)   Cost of equipment and facilities.

Such a system may serve as a depository for red mud  tailings,  a
source  of  process  water for the plant, and a cooling pond.  In
some instances the  system  installed  may  be  large  enough  to
satisfy  the  first  two  uses  only.    In  this configuration,  a
cooling tower is an alternative for the cooling water supply.

The cost of land is a  major  consideration  in  any  impoundment
scheme.     Estimated   current  land  costs  range  from  $20 0/ha
($500/ac)   to  $1200/ha  ($3000/ac).    However,   most   bauxite
refineries   have   acquired   the   needed  land  years  ago  at
substantially lower unit cost.
                           73

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The cost of constructing the earthen dikes of a totally  new  mud
lake  reservoir  are  separable  and  identifiable,  and  are  so
reported.  Even here, costs may not be  entirely  comparable,  if
one or more dikes of an existing lake is available.

The  cost of equipment and facilities is difficult to reduce to a
unit cost basis, since the  major  portion  of  these  costs  are
associated   with   the  construction  of  the  first  mud  lake.
Relatively minor costs may be incurred in relocating some of  the
equipment and facilities.


Thus,  although  the  share  elements, listed above, comprise the
cost for total  impoundment,  available  cost  data  are  not  so
categorized.  Not one producer supplied cost data by waste stream
in  a usable form; only the aggregate figure was supplied.  Thus,
only  total  capital  costs  are  generally  available,  and  the
accuracy of these are suspect to some extent, where a timespan of
10-30   years   may  be  involved.   Nevertheless,  within  these
limitations, capital costs reported are regarded as good order of
magnitude values for past construction.

An  additional  factor  requiring  consideration   in   comparing
reported  costs  is  the type of bauxite to which the data apply.
As indicated by Table 14,  there  can  be  a  sixfold  difference
between  mud  production rates.  However, total costs of disposal
do not appear to be directly proportional to ton of  mud/day,  or
size  of  plant.   Reported costs for plants processing all three
basic categories of bauxite ore are presented in Table  15.   The
dollar  capital  and annual operating costs are as reported.  The
unit capital costs are based on  the   (estimated)   total  alumina
production  represented by the capacity of the impoundment lakes.
Unit operating costs were  determined  by  apportioning  reported
operating  cost  expenditures over the annual alumina capacity of
the plant.

Based on these data, impoundment of the  processing  wastes  from
Surinam  bauxite  requires  a  capital  investment  of  $0.25  to
$0.50/ton mud impounded and an operating  cost  of  about  $0.90-
$1.30/ton  of  mud   ($0.30  -$0.43/ton of alumina).  For Jamaican
ore, with its higher mud yield, capital costs are about $0.20/ton
of mud and operating costs about $0.50/ton  of  alumina.   Lowest
costs,  on a mud basis, are associated with mud-prolific Arkansas
bauxite, of the order of $0.10 to 0.20/ton of mud  capital  costs
and  about $0.10 to 0.25/ton of mud operating costs.  In spite of
the approximate nature of  the  data,  there  is  a  surprisingly
narrow range in waste disposal costs.

Estimated  costs  have  also  been  supplied  by the producer for
Plants G and H.  Neither of these plants currently has facilities
for impounding red mud, although both are committed to  doing  so
by  order  of  a Federal consent decree (Plant G by July 1, 1975,
and Plant H by July 1, 1974).  In  both  cases,  the  impoundment
will  constitute  a  grass-roots installation, complicated by the
fact that the whole configuration of the water circuits will have
                            74

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            TABLE 14.  UNIT MUD PRODUCTION RATES FOR VARIOUS
                       BAUXITES(a>
Tons mud/ton Al-203 produced
Tons mud/ 1000 T/D A1203
Volume of mud, cu m/d^"3)
Volume of mud, cu m/yr
Volume of mud, acre feet/yr
Type
Surinam
0.33
330
410
147,600
120
of Bauxite
Jamaica
1.0
1,000
1,248
449,280
364
Ore
Arkans as
2.0
2,000
2,496
994,560
728
(a)   Per 1000 metric tons of alumina production/day.

(b)   Density of settled mud taken at 1600 kg/m3 (100 lb/ft3) and
     solids at 50%.

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TABLE 15. SUMMARY OF WASTE DISPOSAL COST DATA
Lake Capacity,
metric tons dry nrud
Capital Cost, $
Unit Capital Cost,
$/metric ton mud
Annual Cost, $/yr
Mud, metric tons/yr
Unit Annual Costs,
$/metric ton mud
$/metric ton alumina
A
C

D
Old Pond^b^ New Pond
820,000
Surinam
0.33
4.2xl06
$1.13 x 10
0.26
$264,000
205,000
$1.29
0.43
325,000
Arkansas
2.0
ll.lxlO6
6 0.9xl06
0.08
75,600
660,000
0.11
0.22
755,000
Arkansas
2.0
7.5x106
0.69x106
0.09
373,000
1,520,000
0.24
0.48
755,000
Arkansas
2.0
11.7xl06
2.06xl06
0.18
—
—
—
Notes: (a) Mud basis, in 1971 dollars.
(b) Construction costs of old pond were expensed as incurred;
(c) Exemplary plant, zero discharge of pollutants.
(d) Annual costs represent average costs for two old ponds.
(e) Lbs mud/lb .of alumina produced.
(f) Very large lake; estimated capacity includes 20-year life
E
F
B
(b) Old Pond
9.52xl06
0.18
571,000
1,160,000
0.49
0.49
560,000 560,000
Surinam Surinam
0.33 0.33
3.0xl06 1.7xl06
1.26xl06 0.82x10$
0.52 0.48
166,000
187,000 -- -
0.89
0.30
1,150,000
Jamaican
1.0
—
0.30
,
—
0.35
new pond on capitalized basis.
still remaining.

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 to  be  reoriented toward   impounding  rather   than   toward   direct
 discharge.    Significant   piping  changes  can  be  anticipated.   The
 problem  at  Plant G  is  further complicated by  the fact  that  land
 for impounding  is not available adjacent to the plant, which is
 in  a metropolitan area, and the red mud lake  will be   located  10
 miles  from  the plant.

 The estimated costs,  as  supplied by the  producer,  are summarized
 in  Table  16.  Estimated capital costs were not detailed  so  that
 it  cannot  be stated  how costs are apportioned.  Plant H  is  part
 of  a large  chemical complex and definitive data  on division  of
 effluent  treatment costs  between  the  bauxite refinery  and the
 rest of  the complex are not available.  It is apparent,  however,
 that these  estimated costs differ from those  reported  by the  rest
 of  the industry by  an  order of magnitude.

 It  should  be  noted  that  the  impoundment of   red mud solids
 achieved  by the proposed  installation by  plants  G  and H   is   not
 total.    According   to   a  letter  to   the  U.S.  Environmental
 Protection  Agency  by the  producer   (14) t    there   will    be
 approximately 72 million  ton/day  of suspended solids discharged.
                    Nonwater Quality Aspects
Energy Requirements
Pumping	Costs.  The energy consumed in pumping red mud and other
effluents to an  impoundment  reservoir  is  comparable  to  that
required  to  pump  them  to  a  discharge outfall in a navigable
waterway, so the incremental energy usage  is  nominal.   By  the
same reasoning, energy consumed in returning the supernatant from
the  lake  to  the  plant  is comparable to that required to pump
fresh water to the process.

Evaporation Costs.   Depending  upon  the  location  and  overall
design  and  management  of  the  water  circuit  of a plant, the
evaporation of excess water may be necessary to  avoid  discharge
of  effluents  from the circuit.  Thus, the expenditure of fossil
fuel, in variable quantities, may  be  necessary;  this  presumes
that  the  water  to  be  evaporated will always be less than the
quantity routinely evaporated to satisfy process requirements.

In support of the latter conclusion, the producer  has  estimated
that  200  gal/min  of rain water (1200 ton/day)  might have to be
evaporated if Plants G and H went to a-closed circuit, with total
recycle of process waters.  However, it is estimated  that  water
evaporated  from the calcining kilns at these two plants is about
8680 ton/day, and the  steam  rate  is  about  UOO  ton/hr  (9600
ton/day)  for a total evaporative load of over 18,000 ton/day.  If
evaporation  of  rain water became necessary the evaporative load
would be increased by only about 6 percent.   (The  water  balance
calculations  presented  in  Section VII suggest that this should
not  occur).   Also,  discharge  of  excess   rainwater  has  been
addressed in the promulgated regulations.
                          77

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                              16.  SUMMARY OF ESTIMATES  OF FUTURE  WASTE DISPOSAL COST DATA
                                                                                           (a)
-J
00

Plant Capacity, metric tons/yr
fianxite Type
Mud Ratio
Lake Capacity, metric tons
dry mud^°}
Capital Cost, $^e)
Unit Capital Cost,
$/metric ton dry mud
Annual Cost/ $/y>r^e^
Mud, metric tons/yr
Unit Annual Costs, $/metric ton mud
$ /me trie ton A ^63
Plant G(b)
1,100,000
Jamaican
1.0
8.25 - 11 x 106
21,700,000
1.97 - 2.63
5,487,000
1,100,000
4.99
4.99
.mant H^
; '865,000
;^aican
1.0
^.5 - 8.7 x 10*
14,850,000
1.70 - 2. 28
4,391,000
865,000
5.07
5.07
                  (a)  In 1973-1974 dollars
                  (b)  .Plant does not now have  a  red  mud laks
                  (c)  Lbs mud/lb of alumina produced  (approximate)
                  (d)  Some uncertainty  on life of  pond, depending on efficiency of
                       proposed dewatering system;  estimated  by producer at from 705-10 years
                  (e)  Estimate supplied by producer

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Solids Disposal

The  volume of solid wastes (i.e., red mud)  generated annually by
the bauxite refining industry has been calculated to be 7,500,000
kkgs, equivalent to approximately 9.3 million  cubic  meters   (12
million cubic yards) per year.  This represents about 7600 ac ft,
which,  taken  at  an  assumed  mud lake-filled depth of 25 feet,
means the diversion from other uses of an average of  300  ac  of
land per year.
                           79

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                           SECTION IX
          BEST PRACTICABLE CONTROL TECHNOLOGY CURRENTLY
           AVAILABLE —EFFLUENT LIMITATIONS GUIDELINES
                          Introduction

The  effluent limitations which must be achieved by July 1, 1977,
are to  specify  the  degree  of  effluent  reduction  attainable
through   the   application   of  the  best  practicable  control
technology currently available.  This technology  is  based  upon
the average of the best existing performance by plants of various
sizes,  ages,  and  unit processes within the industrial category
and/or subcategory.  This average is not based upon a broad range
of plants within the bauxite refining industry, but is based upon
performance levels achieved by exemplary  plants.   Consideration
must also be given to:

    (a)  The total cost of application of technology in  relation
         to  the  effluent reduction benefits to be achieved from
         such application.
    (b)  The size and age of equipment and facilities involved.
    (c)  The processes employed.
    (d)  The engineering aspects of the  application  of  various
         types of control techniques.
    (e)  Process changes.
    (f)  Nonwater quality environmental impact (including  energy
         requirements).

Best  practicable control technology currently available not only
emphasizes treatment facilities at the  end  of  a  manufacturing
process,  but  includes the control technology within the process
itself, when the latter  is  considered  to  be  normal  practice
within an industry.

A further consideration is the degree of economic and engineering
reliability  which  must  be established for the technology to be
currently available.  As  a  result  of  demonstration  projects,
pilot  plants  and general use, there must exist a high degree of
confidence in the engineering and economic practicability of  the
technology  at  the  time  of  commencement  of  construction  or
installation of the control facilities.

            Effluent Reduction Attainable Through The
            "Application of Best Practicable Control"
                 Technology Currently Available


Based upon the information contained in Sections III through VIII
of this report, a determination has been made that the degree  of
effluent reduction attainable through the application of the best
                         81

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practicable   control   technology    currently   available   is  no
discharge of process waste water pollutants  to navigable waters.

        j
           Identification of  Best Practicable Control
              '"  Technolog"currently_AyaiIable


Best practicable control technology  currently available  for  the
bauxite refining  industry is recycle and  reuse  of  process  waters
within  the operation.  To implement  this requires:

     (1)  Acquisition of land,  and  construction,  operation,  and
         maintenance  of  dikes  to  provide  one  or  more permanent
         lakes for ore tailings as well  as  reservoirs  for  the
         plant water circuit.
    ^(2)  Provision for  means of   cooling  the  effluent   from
    ,     barometric condensers for reuse in  the  plant, by the use
         of cooling towers or by use of the  plant lake system.
     (3)  Retention of all general wastes  (e.g.,  solution  spills,
         floor   and   equipment  washes,  spent  heat  exchanger
         cleaning  acid, acid   filter,  cloth washes,  and  other
   (      miscellaneous  waste waters within  the  processing  plant)
         by subsequent treatment and reuse or disposal  on  land.
   '.      Maintenance  of  the integrity of  floor slabs and curbs
         around plant areas will be  a feature   of   such  control
         measures.

There   will be, in addition,  some nonprocess waste  streams  (e.g.,
w/ater softener backwash and boiler blowdown) for which control is
more applicable than treatment*  These wastes,   relatively  small
^.n comparison  with the main stream,  can  be readily incorporated
•into and included  as part of  the total impoundment  system.

'The technologies and levels of effluent  reduction   stated  above
have  been  demonstrated  to  the following degree by the existing
plants  in the industy:

     (a)  Two plants are known to be  currently operating  with  no
         discharge of water.
     (b)  Four other plants  have  prepared  or   are implementing
         plans  to achieve   no discharge  of process waste  waters
         before the effective date of the  effluent  limitations.
     (c)  Two plants are currently discharging all wastes, but are
         implementing plans to impound red mud.

        Rationale for the gelection of the_Best Practicable
             Control Technology Currently  AvallaEle"


Acre and Size of Equipment and Facilities

As set  forth in previous sections of  this  report,  the  bauxite
refining industry  is characterized by:
                          82

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     (a)  very large plants, the smallest producing  900   kkgs(lQOO
         tons) /day  of  alumina,  and  the largest  producing  3600
         kkg(4000 tons) /day.
     (b)  A plant age differential of 30 years.
     (c)  A commonality of process and  equipment  design arising
         from  the  universal  use  of  the  Bayer  or combination
         process and that five of the nine existing plants   were
         designed and built by one company.

These  similarities, coupled with the similarities  of waste water
characteristics  substantiate  the   best   practicable   control
technology currently available to be total recycle.

Total Cost of Application. in Relation_to .Effluent
Reduction~Benefits                 ~

Based  upon  the  information  contained  in  Section  VIII,  the
industry as a whole would have to invest an estimated maximum of
$42,000,000 to achieve the promulgated regulations*  This amounts
to  approximately  a  0.5  percent  increase in projected capital
investment for seven of the nine  domestic  refineries   and   12.0
percent for the two remaining ones (Plants G and H) .

operating  costs  for  the production of alumina from bauxite are
estimated to be on the order    of $55/kkg <$50/ton) of  alumina,
Increases  in  operating  costs  to  achieve  the limitations are
estimated at $1,200,000 for seven of the nine U.S.  refineries and
$9,500,000 for the other two.

It  is  concluded  that  the  benefits  derived  from  the  total
elimination of process waste water pollutants to navigable waters
outweigh the costs.  Twenty-two percent of the plants are already
achieving no discharge of process waste water pollutants.  Fifty--
five  percent  are  achieving  no  discharge  of  red mud and are
discharging only minor quantities  of  other  process  waters to
surface  waters; no discharge of pollutants from these plants can
be readily achieved  at  moderate  cost.   Only  two  plants  (22
percent)  still discharge major process waters to surface waters.

Process .Employed

There  is only one product from U.S.  bauxite refineries, purified
alumina.   The process chemistry is basically quite  simple.   The
Bayer   process   or  the  combination  process  modification  is
universally used in the United States.   Accordingly, the  process
flowsheets  are  essentially the same and the discharges are  very
similar.   There is no evidence  that  operation  of  any  current
process  or  subprocess will substantially affect capabilities to
implement  the  best  practicable  control  technology  currently
available.

Engineering Aspects__of ^
This  level  of  technology  is  practicable  because  twenty-two
percent of the plants in  the  industry  are  now  achieving  the
                         83

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effluent  reductions  set  forth  herein,  and another fifty-five
percent can achieve them with only minor  process  changes.   The
concepts  are  proven,  available  for implementation, and may be
readily adopted through adaptation or  modification  of  existing
production facilities.

Process changes

This  technology  is  an  integral  part  of the waste management
program now being implemented within the industry.  While it does
require  process  changes  at  some  plants,  these  changes  are
successfully practiced by other plants in the industry.
     }
Nonwater Quality Environmental, pnpact

Total impoundment has a potential effect upon soil systems due to
strong  reliance  upon the land for ultimate disposition of final
effluents.  Total annual land requirement for waste  disposal  is
of the order of 120 ha (300 ac)  per year.  Impoundment areas must
be  impermeable  to prevent the wastes from contaminating surface
or subsurface waters.  Air pollution could be a problem  in  arid
locations  from  fugitive  dust blowing from abandoned mud lakes.
This has been controlled by keeping  the  surface  of  the  ponds
wetted.
                           84

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                            SECTION X
                   BIST_AyAILABLE_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  no
discharge of process waste water pollutants to navigable waters.
                        85

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                           SECTION XI
                NEW SOURCE PERFQRMANCE_STANDARDS

The best available demonstrated  control  technology,  processes,
operating methods, or other alternatives is identical to the best
practicable   control   technology   currently   available.   The
corresponding standard of performance is no discharge of  process
waste water pollutants to navigable waters.
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                           SECTION XII
                         ACKNOWLEDGMENTS
The Environmental Protection Agency would like to thank the staff
of the Battelle Memorial Institute  (Columbus) under the direction
of Mr. John B. Hallowell for their aid in the preparation of this
document.     Assistance    from   representatives   of   General
Technologies Corporation is also appreciated.

The Project officer, George S. Thompson, Jr., would like to thank
his associates in the Effluent Guidelines  Division,  namely  Mr.
Allen  Cywin, Mr. Ernst P. Hall, and Mr. Walter J. Hunt for their
valuable suggestions and assistance.

Mr. Harry Thron, Effluent Guidelines  Division,  was  responsible
for  the  proposed  regulation  and development document (October
1973)  for this industry.
The  members  of  the  working   group/steering
coordinated the internal EPA review are:
committee   who
    Mr. Walter J, Hunt, Chairman, Effluent Guidelines Division
    Mr. Marshall Dick, office of Research and Development
    Mr. John Ciancia, National Environmental Research
     Center, Edison
    Mr. Lew Felleisen, Region III
    Mr. Swep Davis, Office of Planning and Evaluation
    Mr. Taylor Miller, Office of General Counsel

Appreciation  is also extended to the follwing trade associations
and corporations for assistance and cooperation provided in  this
program:

    Aluminum Company of America
    Kaiser Aluminum and Chemical Corporation
    Martin - Marietta
    Ormet  corporation
    Reynolds Aluminum

Finally,  many  thanks  are given to the hard working secretarial
staff  of  the  Effluent  Guidelines  Division.   In  particular,
recognition  is  given  to Ms. Linda Rose, Ms. Kay Starr, and Ms,
Nancy Zrubek*
                         89

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                          SECTION XIII
                           REFERENCES
(1)  Metal Statistics, 1972, American Metal Marker, Fairchild
    Publications, Inc., N.Y., N. Y.

(2)  Hayward, C.R., "An Outline of Metallurgical Practice",
    3rd Ed., D. Van Nostrand, N, Y., 728 pp  (1952).
                  —»
(3)  Garden, Clair, Texas Water Quality Board, Personal
    Communication (June, 1973).

(4)  Todd, D.K., "The water Encyclopedia", Water Information
    Center, Water Research Building, Port Washington, N. Y.
    (1970).

(5)  Hudson, L.K., "Recent Changes in the Bayer Process",
    from "Extractive Metallurgy of Alumina", Vol. I,
    Alumina, Gerard,  G., and Stroup, P. T., editors,
    Interscience Publishers, N.Y., 355 pp (1963).

(6)  U.S.  Naval Service World wide Summaries, Vol. VIII,
    Part 5, U.S.A.,  Mississippi Valley Area. Environmental
    Technical Applications Center (U.S. Air Force),
    Washington, D.C.  (1961) AD699 917.

(7)  Kirk-Othmer, "Encyclopedia of Chemical Technology",
    2nd Ed., Vol. I  (1963).

(8)  Rushing, J.C., "Alumina Plant Tailings Storage", Paper
    No.  A73-58, Metallurgical Society of AIME, Chicago, 111.,
    Feb.  25-28, 1973.

(9)  "Utilization of  Red Mud Wastes for Lightweight
    Structural Building Products".  IITRI Project No.
    G-6015, prepared  for U.S. Bureau of Mines.

(10)Fursman, O.C., Mauser,  J.E., Butler, N. o,, and Stickney,
    W.  A.,  "Utilization of  Red Mud Residues from Alumina
    Production", U.S.  Dept. of the Interior, Bureau of Mines,
    Report  of Investigations No. 7454 (1970).

(11)Guccione, E., "'Red Mud1, a Solid Waste Can Now be
    converted to a High-Quality Steel", Eng. S Mining J.,
    V72,  9, 136-7 (1971).

(12)Solyman, K., and  Bujdoso, E., "Properties of Red Mud in
    the  Bayer Process  and Its Utilization", Paper NO.
    A73-56, Metallurgical Society of AIME, Feb, 28-Mar. 1, 1973,
    Chicago, Illinois.
                         91

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(13)Good,  P.C.,  and Fursman,  O,C.,  "Centrifugal Dewatering
    of  Jamaican  Red Mud",  U.S.  Dept.  of the Interior, Bureau
    of  Mines,  Report of investigation No.  7140 (June, 1968).

(14)Day, J.V.  Letter to R,B.  Elliott, Permits Branch,
    U.S. Environmental Protection Agency,  Region VI,  Dallas
    February 27, 1973.
                          92

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                           SECTION XIV
                            GLOSSARY


Acidity

The concentration of acid ions expressed as pH for a solution.

Act

The Federal Water Pollution Control Act Amendments of 1972.

Alkalinity

The alkali  concentration  or  alkaline  quality  of  an  alkali-
containing substance.

Alumina

Any of several forms of aluminum oxide, Al^OS, occuring naturally
as  corundum,  in  a  hydrated  form in bauxite, and with various
impurities as ruby, sapphire, and emery.

Autoclave

A strong, pressurized, steam heated  vessel,  used  to  establish
special  conditions for chemical reaction, for sterilization, and
for cooking.

Baghouse

Large chamber for holding bags used in the  filtration  of  gases
from  a  furnace,  for  the  recovery of metal oxides and similar
solids, suspended in the gases.

Barometric Condenser

An apparatus used to condense vapor,  in  which  the  vapors  are
condensed   by   direct  contact  with  water  in  a  vessel  set
sufficiently  high  so  that  the  water  drains  from  it  in  a
barometric hot-leg into a sealed tank or hot-well.

Bayer Process

Process in which impure alumina in bauxite is dissolved in a hot,
strong  alkali solution, normally NaOH, to form sodium aluminate,
which upon diluting and cooling the solution, hydrolyzes, forming
a precipitate of pure aluminum hydroxide.

Bauxite
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An  impure  mixture  of  earthy  hydrous  aluminum   oxides   and
hydroxides  that  commonly contain similar compounds of iron, the
principal ore of aluminum.

Best_Available Technoj.pgy Economically Achievable

Level of technology applicable  to  effluent  limitations  to  be
achieved  by  July  1, 1983, for industrial discharges to surface
waters as defined by Section 301  (b)(1)(A) of the Act.

Igs^ggacticable^ ContrQ^T

Level of technology applicable  to  effluent  limitations  to  be
achieved  by  July  1, 1977, for industrial discharges to surface
waters as defined by Section 301 (b) (1) (A) of the Act.

Bioghemica^ Oxygen Demand  (BOD}

A measure of the oxygen demand in sewage and industrial wastes or
in the stream, determined by chemical techniques.  One  technique
(BOD5) determines the 5-day oxygen demand.

Slowdown

A  discharge from a system, designed to prevent a buildup of some
material, as in a boiler to control dissolved solids.
Thefinal solid waste remaining after the alumina is leached  from
the calcined red mud in the combination process.
The diked reservoir  (tailings pond) used to impound brown mud,
The  roasting or burning of any substance to bring about physical
or chemical  changes;  e.g. ,  the  conversion  of  lime  rock  to
quicklime,
Financial charges which are computed as the cost of capital times
the  capital  expenditures  for  pollution  control.  The cost of
capital is based upon a weighted average of the separate costs of
debt and equity,

Category and Subcategpry

Divisions of a particular industry which possess different traits
which effect  waste  treatability  and  would  require  different
effluent limitations.
                           94

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Caustic Soda

Sodium hydroxide  (NaOH)

                Demand  (COD)
A  measure  Of  the  oxygen  demand equivalent of that portion of
matter in a sample which is susceptible to oxidation by a  strong
chemical oxidant.                              •

Clear Water Lake

Nominally  the  lake  relatively  free  of  alkalinity  and other
dissolved solids used as a fresh water reservoir  for  a  bauxite
refinery.

Combination Process

Variation  of  Bayer  process used for high-silica ores, in which
the red mud from the first stage Bayer process is  calcined  with
soda ash and lime and leached to recover additional alumina.

Conductivity

A  measure  of  the  ability of water in conducting an electrical
current.  In practical terms, it is used  for  approximating  the
salinity or total dissolved solids content of water.

Continuous Countercurrent Decantation (CCD)_

A continuous system of washing finely divided solids, such as red
muds,  to free them from liquids containing dissolved substances.
In practice, the fresh wash water and the strong solids start  at
opposite  ends  and  move  countercurrently toward each other, so
that the freshest  water  contacts  the  most  thoroughly  washed
solids.
Accounting  charges  reflecting  the  deterioration  of a capital
asset over its useful life.
Pressure vessel or autoclave; vessels in  which  the  alumina  is
dissolved from the bauxite.

Effluent

The  waste  water  discharged  from  a  point source to navigable
waters.

Effluent Limitation
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A  maximum  amount  per  unit  of  production  of  each  specific
constituent  of the effluent that is subject to limitation in the
discharge from a point source.

Electrostatic Precjpitator

A  gas  cleaning  device  using  the  principle  of  placing   an
electrical  charge on a solid particle which is then attracted to
an oppositely-charged collector plate.  The collector plates  are
intermittently  rapped  to  discharge  the  collected dust into a
hopper below.

Ganaue
The worthless rock or other material in which valuable metals
minerals occur.
                                        or
The  aluminum- bearing
further processing.
Industrial
solution from the bauxite digesters before
All wastes streams within a  plant.   Included  are  contact  and
noncontact  waters.  Not included are wastes typically considered
to be sanitary wastes.

           qpsts
The capital expenditures  required  to  bring  the  treatment  or
control  technology into operation.  These include the traditonal
expenditures such as design, purchase of land and materials, site
preparation, construction and installation, plus  any  additional
expenses   required   to  bring  the  technology  into  operation
including expenditures to establish related necessary solid waste
disposal.
Milligrams per liter.  Nearly equivalent  to  parts  per  million
concentration.
Any  building,  structure,  facility,  or installation from which
there  is  or  may  be  a  discharge  of  pollutants  and   whose
construction  is  commenced after the publication of the proposed
regulations.
Performance standards for the industry and applicable new sources
as defined by Section 306 of the Act.
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Operations  and Maintenance

Costs   required  to  operate   and  maintain   pollution   abatement
equipment,  such as labor, material, insurance, taxes, solid waste
disposal, etc.

£H

A measure of the alkalinity or acidity of a  solution, numerically
equal   to   7  for  neutral  solutions, increasing with  increasing
alkalinity  and decreasing with increasing acidity.   A   one  unit
change  in pH indicates a tenfold change in acidity or alkalinity.

Plant Effluent_or_Dj.scharqe After Treatment

The  volumes of waste water discharged from  the industrial plant.
In this definition, any waste  treatment device   (pond,   trickling
filter, etc.) is considered part of the industrial plant.

Pregnant Liquor

Solution  containing  the metal values prior to their removal and
recovery.

Point Source

A single source of water discharge such as an individual plant.

Process Effluent or Discharge

The volume  of water emerging from a particular process  use in the
plant.

Process Lake

Reservoir used for process water; often in   closed  circuit  with
part of process; not used for mud disposal,

Red Mud Lake

The diked reservoir used to impound red mud.

Secondary Treatment

Biological treatment provided beyond primary  clarification.

Silicates

A  chemical  compound containing silicon,  oxygen, and one or more
metals.

Standard of Performance

A maximum weight discharged  per  unit  of  production  for  each
constituent  that  is subject to limitation and applicable to new
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sources, as opposed to existing  sources  which  are  subject  to
effluent limitations,

storm Water Lake

Reservoir  for storage of storm water runoff collected from plant
site; also/ auxilary source of process water.
Navigable waters.  The waters of the United States including  the
territorial seas.

Thixotropic

Having  the property exhibited by certain gels of liquefying when
stirred or shaken  and  returning  to  the  hardened  state  upon
standing.

Total Suspended Solids_ (TSS)

Solids found in waste water or in the stream, which in most cases
can be removed by filtration.  The origin of suspended matter may
be man-made or of natural sources, such as silt from erosion.

Unit Operation

A  single, discrete process as part of an overall sequence, e.g.,
precipitation, settling, filtration.
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                                  CONVERSION TABLE
 MULTIPLY (ENGLISH UNITS)

     ENGLISH UNIT      ABBREVIATION
 acre                    ac
 acre - feet             ac ft
 British Thermal
   Unit                  BTU
 British Thermal
   Unit/pound            BTU/lb
 cubic feet/minute       cfm
 cubic feet/second       cfs
 cubic feet              cu ft
 cubic feet              cu ft
 cubic Inches            cu in
 degree Fahrenheit       F°
 feet                    ft
 gallon                  gal
 galIon/minute           gpm
 horsepower              hp
 inches                  in
 inches of  mercury       in Hg
 pounds                  Ib
 million gallons/day     mgd
 mile                    mi
 pound/square
   inch (gauge)           peig
 square feet             s
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