EPA 440/1-73/005
   Development Document for Proposed
      Effluent Limitations Guidelines
  and New Source Performance Standards
                  for the
               CEMENT
   Manufacturing Point Source Category
                        \
 UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
                 AUGUST 1973

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                          Publication Notice








     This is a development document for proposed effluent



limitations guidelines and new source performance standards,



As such, this report is subject to changes resulting from



comments received during the period of public comments



of the proposed regulations.  This document in its final



form will be published at the time the regulations for



this industry are promulgated.

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            DEVELOPMENT DOCUMENT FOR
        EFFLUENT  LIMITATIONS GUIDELINES
          AND STANDARDS OF PEPFORMANCE
         CEMENT MANUFACTURING CATEGORY
                   John Quarles
               Acting Administrator

                 Robert L. Sansom
Assistant Administrator for Air & Water  Programs
                    Allen Cywin
     Director,  Effluent Guidelines Division

                    John Riley
                  Project Officer
                  September, 1973

          Effluent Guidelines Division
        Office  of Air and Water Programs
      U.S. Environmental Protection Agency
             Washington, D. C.   20460
              Environmental Protection Agency
              Li IT': ":,  ''. v^lon V
              1 l^nh  ">V?-,;;c^r Brive
              Chicago,  Illinois  60606

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                                ABSTRACT

This report presents the findings of a study of the cement manufacturing
industry by Southern Research Institute for the Environmental Protection
Agency for the purpose of developing effluent limitation  guidelines
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  available  technology  economically  achievable
which  must  be  achieved by existing plants by July 1, 1977 and July 1,
1983  respectively;  and  standards  of  performance;  and  pretreatment
standards  for  the  industry  —  setting  forth the degree of effluent
reduction achievable through  the  application  of  the  best  available
demonstrated  control technology, processes, operating methods, or other
alternatives — to implement Sections 304, 306, and 307 of  the  Federal
Water Pollution Control Act, as amended.

Nonleaching plants can achieve essentially no discharge of pollutants by
July  1,  1977  through  the  implementation of technology consisting of
recycling and  reuse,  or  isolation  of  cooling  water  from  possible
contamination  and  containment  of  runoff  from kiln dust piles.  This
technology also applies  to  1983  limitations  and  standards  for  new
sources,  and  to  the  nonleaching  streams  at.  leaching  plants.  For
leaching streams, the recommended limitations for 1977 are a pH  of  6.0
to  9.0 and suspended solids of not more than 0.15 kg/kkg (0.30 Ib/t)  of
dust   leached   achievable   by   neutralization   and   sedimentation.
Elimination  of  dissolved  solids  by 1983 will require the transfer of
treatment technology from other industries.

Supporting data and  rationale  for  the  development  of  the  proposed
guidelines and standards are contained in this report.

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                           CONTENTS

Section                                                  Page

  I      Conclusions                                      1

 II      Recommendations                                  3

            Best Practicable Control Technology           3
              Currently Available
            Best Available Technology                     3
              Economically Achievable
            New Source Performance Standards              3

III      Introduction                                     5

            Purpose and Authority                         5
            Basis for Guidelines Development              6
            Description of the Cement Manufacturing       14
              Industry
            Description of the Manufacturing Process      16
            Kiln-Dust Considerations                      20

 IV      Industry Categorization

            Introduction                                  25
            Factors Considered                            25

  V      Water Use and Waste Characterization             33

            General                                       33
            Specific Water Uses and Waste                 33
              Characteristics

 VI      Selection of Pollutant Parameters                41

            Definition of Pollutants                      41
            Parameters Selected as Pollutants             41
            Rationale for Selection of Specific           42
              Parameters as Pollutants
            Rationale for Rejection of Specific           45
              Parameters as Pollutants
                           111

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                           CONTENTS
Section
VII
VIII
 IX
  X
 XI
Control and Treatment Technology                 49

   Introduction                                  49
   In-Plant Control Measures                     50
   Treatment Technology                          52
   Description of Plants That Demonstrate        60
     Control and Treatment Technology

Cost, Energy, and Nonwater Quality Aspects       73

   Cost and Reduction Benefits of Alternative    73
     Control and Treatment Technologies
   Effects of Costs on the Industry              79
   Energy Requirements                           79
   Nonwater Quality Aspects                      79

Effluent Reduction Attainable Through            87
Application of the Best Practicable
Control Technology Currently Available;
Effluent Limitations Guidelines

   Introduction                                  87
   Identification of BPCTCA                      88
   Rationale for Selection of BPCTCA             89

Effluent Reduction Attainable Through
The Application of the Best Available            93
Technology Economically Achievable;
Effluent Limitations Guidelines

   Introduction                                  Q3
   Identification of BATEA
   Rationale for Selection of BATEA              9.,

New Source Performance Standards and             97
Pretreatment Standards

   New Source Performance Standard               97
   Pretreatment Standards                        97
                           IV

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                           CONTENTS

Section                                                  Page
XII      Acknowledgments                                  99

XIII     References                                       101

XIV      Glossary                                         105

             Definitions and Terminology                  105
             Conversion Factors                           HI

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                     FIGURES


                                              PAGE

 1    Waste Water Survey Questionnaire          ,s

 2    Sample Data Sheet                        11

 3    Geographical Distribution of              15
         Operating Cement Plants

 4    Flow Sheet for the Manufacture           IQ
         of  Portland Cement

 5    Kiln Dust Collection and Handling        22

 6    Comparison of Loading of Selected        27
         Parameters for Leaching and Non-
         leaching Plants

 7    Diagram of Water Usage  in Cement          36
         Manufacturing

 8    Distribution of Reported Maximum  pH      44

 9    Distribution of Calculated Average       46
         Temperature Rise

10    Solubility of Calcium Carbonate as       53
         a Function of pH

11    Diagram of Electrodialytic Treatment     55
         of Leachate

12    Flow Sheet for the Recovery of           61
         Potassium Sulfate from Kiln Dust

13    Diagram of Water-Management Plan  for     62
         Plant A

14    Diagram of Water-Management Plan  for     64
         Plant B

15    Diagram of Water-Management Plan  for     66
         Plant C
                      VI

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               FIGURES (continued)
                                             PAGE
16    Diagram of Water-Management Plan for    57
         Plant D

17    Diagram of Water-Management Plan for    69
         Plant G

18    Diagram of Water-Management Plan for    70
         Plant H
                        Vll

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                      TABLES

                                              PAGE

 1    Summary of Features  of  Plants             10
          Studied

 2    Distribution of  Plants  by  Reported       12
          Loading for  18 Parameters

 3    Comparison of Reported  and Measured      ^3
          Waste Loads  at Plants  Visited

 4    Distribution of  Portland Cement          ^7
          Plants by Capacity

 5    Summary of Methods of Dust               23
          Utilization  and  Disposal

 6    Comparison of Loadings  of  Selected       28
          Parameters for Wet- and Dry-
          Process Plants

 7    Comparison of Loadings  and Water          39
          Discharged for Plants  of
          Different Capacity

 8    Comparison of Loadings  for Leaching      34
          and Nonleaching  Subcategories

 9    Summary of Water Usage  for the           35
          Cement Manufacturing Industry

10    Reported Cooling Water  Usage in          37
          Cement Plants

11    Loadings of Pollutant Parameters  for     43
          Leaching and Nonleaching Plants

12    Water Effluent Treatment Cost and        74
          Pollution Reduction Benefits

13    Plant Production Costs                    78

14    Table of Conversion  Factors              11;L
                      Vlll

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                               SECTION 1

                              CONCLUSIONS

For  the  purpose  of  establishing  effluent limitations guidelines and
standards of performance  for  new  sources,  the  cement  manufacturing
industry  is divided into two subcategories: leaching plants (those that
use water in contact with kiln dus-t as an integral part of  the  process
as  in  the leaching of dust for reuse or wet scrubbing to control stack
emissions), and nonleaching plants.

Process waste water pollutants  are  those  constituents  of  discharged
water that are added in measurable quantities (greater than 0.005 kg/kkg
(0.01  Ib/t)  of  product)  as  a  result  of  the  water  being used in
manufacturing operations characteristic of the industry.

Presently about 35 of 154 nonleaching plants are  achieving  essentially
no  discharge  of  pollutants;  that  is, they are discharging less than
0.005 kg/kkg (0.01 Ib/t) of product not including runoff.  The remaining
119 plants can also achieve essentially no discharge  of  pollutants  by
July 1, 1977.

For the approximately 12 plants in the leaching subcategory, substantial
reduction  in  suspended  solids  and pH can be achieved by July 1, 1977
with existing technology.  However, elimination of dissolved  solids  by
July  1,  1983  will  require  the  adaptation  of  additional treatment
technology by the industry.

It is  estimated  that  the  costs  of  achieving  the  limitations  and
standards  for  1977  by  all  plants  in  the  industry  is  less  than
$30,000,000.  As a result  of  implementing  the  1977  limitations  and
standards,  the increased cost of producing cement is estimated to range
from 0.6 to 0.9 percent.

The cost of the additional  treatment  technology  required  for  plants
currently  leaching  to meet 1983 limitations and standards is less than
$U,000,000.  As a  result  of  implementing  the  1983  limitations  and
standards,  the increased cost of producing cement is estimated to range
from  0.6  to  0.9  percent  above  the  costs  required  to  meet  1977
limitations and standards.

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                         SECTION II

                      RECOMMENDATIONS

Best Practicable^Control Technology Currently Available

For  plants  in the nonleaching subcategory, essentially no discharge of
pollutants in manufacturing effluents is recommended as  the  limitation
except  for  temperature  where an increase of 3°C is recommended as the
limitation.  This represents the degree of effluent reduction obtainable
by existing plants by July 1, 1977 through the application of  the  best
practicable control technology currently available.

The  technology  on which this limitation is based consists of isolation
of cooling water from possible contamination, and recycling or reuse  of
other water (including cooling water if not isolated).

Disposal  sites  for  kiln dust should be designed to prevent runoff, or
where  such  runoff  cannot  be  prevented,  it  should  be  treated  by
neutralization  and  sedimentation.  Material  storage  piles  should be
suitably diked to prevent  the  discharge  of  pollutants  to  navigable
waters if a 10 year, 24 hour rainfall event occurs.

For  plants  in  the  leaching subcategory, the degree of improvement in
effluent quality that is achievable  through  application  of  the  best
practicable  control technology currently available is the same as those
for plants in the nonleaching  subcategory  for  all  except  the  dust-
contact  streams  where  reduction  of pH to 9.0 and suspended solids to
0.15 kg/kkg (0.30 Ib/ton)  of dust leached is recommended as the effluent
limitation.

The technology on which the limitation for  leaching  streams  is  based
consists  of segregation of dust-contact streams and neutralization with
stack gases followed by sedimentation.

ggst^Ayailable^TechnglogY^Economically^Achievable

Essentially no discharge of pollutants is recommended  as  the  effluent
limitation  for nonleaching plants and leaching plants to be achieved by
July 1, 1983.
New Spurce^Performance Standards

For leaching plants, this limitation is based on the  use  of  processes
shown  to  be  feasible  in  other industries for reducing the dissolved
content in the leachate stream, and  recycling  the  stream.   One  such

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process  is  electrodialysis, which has been used for more than a decad.».
in Japan for concentrating seawater to produce brines.   tne  definition
of  Best  Available  Technology  Economically  Achievable, the necessar\
technology is available, but may require some development work to  adapt
to this application.

The  effluent  reduction  attainable through the application of the belt
available demonstrated control technology is essentially no discharge :f
pollutants for nonleaching plants and for the nondust contact streams at
leaching plants.  For  the  dust  contact  streams  at  leaching  plants
reduction  of suspended solids to less than 0.15 kg/kkg (0.30 Ib/ton) of
dust leached is attainable These are the standards recommended  for  new
plants  and  are based on the application of the technology described as
Best Practicable, Currently Available.  As the technology  described  as
Best  Available,  Economically Achievable is developed and demonstrated,
the performance standards for new leaching plants should be  revised  to
reflect the recommendation of essentially no discharge of pollutants*

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                              SECTION III

                              INTRODUCTION


Purpose^ and Authority

Section  301(b)   of  the  Act requires the achievement by not latur than
July lf 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 achievement by not later than July 1, 1V83,  of
effluent limitations for point sources, other than publicly own .vd treat-
ment  works,  which  are  based on the application of the best  available
technology economically  achievable  which  will  result  in  reasonable
further  progress  toward the national goal of eliminating the iischarge
of all pollutants, as determined in accordance with  regulations  issued
by the Administrator pursuant to Section 304(b) of 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 \ollutants
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 proposed herein set forth  effluent  limitation1,  guidelines
pursuant  to  Section  304 (b)  of  the  Act for the cement Manufacturing
source category.

Section 306 of the Act requires the Administrator, within  me year after
a category of sources is  included  in  a  list  published  pursuant  to
Section  306(b)    (1) (A)  of the Act, to propose regulations establishing
Federal  standards  of  performances  for  new   sources   within   such
categories.   The  Administrator  published  in  the Federal Register of
January 16, 1973  (38  F.R.  1624),  a  list  of  27  source  categories.
Publication  of the list constituted announcement of the Administrator's
intention of establishing, under Section 306, standards  of  performance
applicable  to new sources in the cement manufactturing -ource category,
which was included within the list published January 16, 1973.

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Basis for Guidelings Development

The  effluent   limitations   guidelines   and   performance   standards
recommended  in  this  report  were  developed from analysis af Corps of
Engineers discharge permit applications and questionnaires  to  identify
potential subcategories, and exemplary plants, and obtain information on
water  use and waste water characteristics.  Furthert on-site studies of
potential exemplary plants were conducted to verify \his information and
observe control and treatment technology  employed.   Also,  discussions
were  held with consultants and others knowledgable of the manufacturing
and waste treatment practices in the industry.

General information was obtained on all plants and detailtsd  information
was collected for 132  (80%) of the 166 domestic cem
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     - Identification of distinguishing features that could
       potentially provide a basis foi subcategorization of
       the industry.  These features included method of dust
       collection and disposal, type of process, raw materials,
       plant size and age, and others, discussed in detail in
       Section IV.

     - Determination of the water usage and waste character-
       istics for each subcategory, discussed in Section V,
       including the volume of water used, the sources of con-
       tamination in the plant, and the type and quantity of
       constituents in the wastewaters.

     - Identification of those constituents, discussed in
       Section VI, which are characteristic of the industry
       and present in measurable quantities, thus being pol-
       lutants subject to effluent limitations guidelines and
       standards.

The results of this analysis, shown in Table 2, indicated that at  least
20% of the plants in the industry are currently achieving essentially no
discharge  of  pollutants, that is, they are discharging less than 0.005
kg/kkg (0.01 Ib/ton) of product which corresponds to about 1  mg/1,  the
minimum  measurable  concentration  at  the  flow  rates  common in this
industry.  The reliability of the reported RAPP  data  was  verified  by
sampling  and analysis at ten plants.  The average measured and reported
loadings of seven nonleaching plants and three leaching plants are shown
in Table 3.  With the exception of dissolved solids at leaching  plants,
the deviation of either measurement from the mean of the

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10.   Water usage information:

                In the table below indicate the source and daily amount  (surface water, municipal, etc.)  of
     intake water and the fate and daily  amount  (surface containment,  surface  streams, evaporation, etc.)  of
     discharged water for each use.  For  recycled water, indicate makeup  amount only under "Source" and esti-
     mate total amount of water that would be consumed without recycling  in  Question No. ]1.  For water that
     is  reused for another purpose, indicate previous usage under "Source" and subsequent use under "Fate".
     For example, if cooling water is reused as slurry water, "Fate"  for  "cooling" is "slurry" and "Source"
     for "slurry" is "cooling".
Intake
Use Source Amount, gpd
Boiler feed
Bearing cooling water
Cement-cooler water
Sanitary
Process (Slurry)
Dust leaching
Dust control
Quarry dewa taring
Contact clinker cooling
Raw material washing and
beneficiation
Other
(specify)
Total intake
Discharge Check if
treated before
Fate Amountj gpd discharge
D
n
D
D
D
D
n
n
n
n
n
Total discharge
11. Describe quantity and use of any water that is recycled


12.   Types of kiln-dust collection system(s) used:

                  I~JCyclones                   [  [wet scrubbers

                  |  |Bag houses                 [  ] None

                  [  [Precipitators              [  [other (specify)


13.   Estimated or designed kiln-dust collection efficiency: ______
14.   Disposition of collected kiln-dust:

     (a)  Returned to kiln:  	 tons/day; alkali content 	%

     (b)  Not returned to kiln:  	 tons/day; alkali content 	%


15.   Method of disposal:   [  ]Surface piling     |  ) Return to quarry

      [   | Utilized in some way (specify)	

      f~] Other  (specify)	
                  Figure  1  (continued).   Wastewater Survey Questionnaire

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10.  Water usage information:

                 In the  table below indicate the source and daily amount  (surface water, municipal, etc.)  of
     intake water and the  fate and daily amount (surface containment,  surface streams, evaporation, etc.)  of
     discharged water for  each use.  For recycled water, indicate makeup  amount only under "Source" and esti-
     mate total amount of  water that would be consumed without recycling  in Question No. 11.  For water that
     is reused for another purpose, indicate previous usage under "Source" and subsequent use under "Fate".
     For example, if cooling water is reused as slurry water,  "Fate"  for  "cooling" is "slurry" and "Source"
     for "slurry" is "cooling".

                                	Intake	  	Discharge	     Check  if
                                                                                               treated before
     	Use	  	Source	  Amount,  gpd   	Fate	  Amount, gpd    discharge

     Boiler feed               	  	   	  	       |	)

     Bearing cooling water     	  	   	  	       I |

     Cement-cooler water       	  	   	  	       |	j

     Sanitary                  	  	   	  	       |	j

     Process (Slurry)           	  	   	  	       |	|

     Dust leaching             	  	   	  	       |	j

     Dust control              	  	   	  	       |	]

     Quarry dewatering         	  	   	  	       |	|

     Contact clinker cooling    	  	   	  	       |	)

     Raw material washing  and                                                                        i—i
       benef iciation           	  	   	  	       |	|
     Other
               (specify)
                                 Total intake     	    Total  discharge
11.  Describe quantity  and use of any water that is recycled
12.  Types of kiln-dust collection system(s) used:

                  I~J Cyclones                    [ J Wet scrubbers

                  [   | Bag houses                  [ ~JNone

                  fIPrecipitators               I[other (specify)


13.  Estimated or  designed kiln-dust collection efficiency:  	
14.  Disposition  of  collected kiln-dust:

     (a)  Returned to kiln:  	 tons/day; alkali content
     (b)  Not returned to kiln:  	 tons/day; alkali content


15.   Method of disposal:   [  ]Surface piling    |  1 Return to quarry

      IjUtilized  in some way  (specify)

          Other  (specify)	
                  Figure  1  (continued).   Wastewater  Survey  Questionnaire

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                                                    DRAFT


                            TABLE 1

             Summary of Features of Plants Studied

Features                                      Number of Plants

Type of Process
Method of Dust Collection and Disposition
           All returned to kiln                       3
           Leach                                      3
           Surface pile or quarry                     8
           Wet slurry                                 1
           Wet scrubber                               1

Plant Age
           Built before 1920                          4
           1920 to 1939                               3
           1940 to 1959                               4
           1959 to present                            4

Plant Capacity , Thousand metric tons/year
           450 or less                                4
           450 to 900                                 9
           Over 900                                   1

Raw Materials
           Limestone                                 10
           Marl                                       2
           Oyster Shell                               3

Type of Primary Fuel
           Gas                                       10
           Coal                                       3
           Oil                                        2

Plant Location
           Northeast                                  3
           South                                      4
           Midwest                                    4
           West                                       4
                              -10-

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-11-

-------
                           TABLE 2

DISTRIBUTION OF PLANTS BY REPORTED LOADING FOR 18 PARAMETERS
Alkalinity
BOD
COD
Total solids
Dissolved solids
Suspended solids
Volatile solids
Ammonia
Kjeldahl nitrogen
Nitrate as N
Phosphorus
Oil and grease
Chloride
Sulfate
Sulfide
Phenols*
Chromium*
Potassium

Number of
Plants
Reporting
78
74
69
79
77
75
73
69
67
69
71
56
67
68
50
56
62
15
waste Load, kg/k*
Less
than
.005
44
59
40
28
27
35
34
69
65
66
71
51
48
36
50
52
55
7
.OU5
to
.049
8
14
17
15
11
13
13
0
1
3
0
3
6
11
0
1
2
1
• w 3
to
.49
15
1
12
11
19
18
15
0
1
0
0
2
9
10
0
3
4
3
;g
0.5
to
4.9
11
0
0
13
8
8
11
0
0
0
0
0
4
10
0
0
1
3

Greater
than
5
0
0
0
12
12
1
0
0
0
0
0
0
0
1
0
0
0
1
*Load expressed in g/kkg.
                           -12-

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-------
two  is  well within the reliability of the test methods.   In subsequent
sections of this report, the  data  base  used  in  the  development  of
charts,  tables, and figures includes all 166 plants except as otherwise
indicated.

The  control  and  treatment  technologies  employed  at   plants   with
essentially  no  discharge  ~of  pollutants  and  at leaching plants were
identified during the on-site studies,  and  are  discussed  in  Section
VIII.


The  information,  as  outlined  above,  was  then evaluated in order to
determine what levels of technology constituted  the  "best  practicable
control   technology  currently  available,"  and  the  "best  available
demonstrated control technology, process, operating  methods,  or  other
alternatives."   In  identifying such technologies, various factors were
considered.  These included the feasibility of using technology employed
by other industries, the total cost  of  application  of  technology  in
relation  to  the  effluent  reduction benefits to be achieved from such
application, the  process  employed,  the  engineering  aspects  of  the
application  of  various  types of control techniques, non-water quality
environmental impact (including energy requirements) and  other  factors
as discussed in sections IX, X, and XI.

Description of the Cement. Manufacturing Industry

The  cement  manufacturing  industry  is classified by the Department of
Commerce as SIC group 3241  (Hydraulic Cement).  The products produced by
the industry are various types of portland cement, manufactured to  meet
different requirements.

There  are  51  companies  with 166 plants currently in operation in the
United States and Puerto Rico.  These plants are widely distributed,  as
shown  on  the map in Figure 3, being located in all but nine states, in
areas close to sources of  raw  materials,  transportation  routes,  and
local markets.

The  number  of plants in operation has declined from a high of 188  (12)
in 1967 to the estimated 166 plants at the end of 1972.  In addition  to
these,  about five plants are presently shut down for modernization, and
five new plants are under construction.   Expansion  programs  are  also
underway or planned at about 20 existing plants.

The  annual  capacity  of  these  plants ranges from 0.18 to 2.7 million
metric tons  (0.2-3.0 million short tons).  Table U shows the  number  of
plants in each of four size categories.

In  1971  the  production  of  clinker  by  domestic plants was about 68
million kkg  (75 million tons).  (7)  According to the U.  3,   Department
                                  14

-------
1
£ — .
Is
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L
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                                           3

-------
of  Commerce  (6),  the  value  of  cement shipments will grow from $1.6
billion in 1971 to $2.2 billion by 1975 and $3.1 billion by 1980.

Excess capacity has existed in the industry since a major  expansion  in
the early sixties.  In 1971, the capacity utilization was about Q8%f and
is  estimated  at 90% for 1972—the highest in over 10 years.  Expansion
programs currently underway should increase capacity about 2%  in  1973.
(6)

Description of the Manufacturing Process

Cement  is  manufactured  by  a continuous process, normally interrupted
only to reline the kilns.  There are 3 major  steps  in  the  production
process:   grinding  and  blending of raw materials; clinker production;
and finish grinding.  These steps are illustrated in Figure 4.

The ordinary ingredients for  the  production  of  cement  include  lime
(calcium  oxide), silica, alumina, and iron.  Lime which constitutes the
largest single ingredient, is most  commonly  obtained  from  limestone,
cement  rock,  oyster shell marl, or chalk, all of which are principally
calcium carbonate.  Materials such as sand, clay, shale,  iron  ore  and
blast  furnace  slag  are  added to obtain the proper proportions of the
other ingredients.  At some plants it is necessary  to  beneficiate  the
raw  materials  before  they  can  be  used.   For  example, if the most
economical supply of clay contains too much sand,  the  mixture  can  be
separated by washing with water.

Two  types of processes are used in the manufacture of cement, "wet" and
"dry."  At wet plants, the raw materials are ground with water  and  fed
to  the  kiln  in  a  slurry.  At dry plants the raw materials are dried
before grinding,  and are ground and fed to the kiln in a dry state.  The
moisture content of the raw materials available at a given location
                                  16

-------
                                                   DRAFT

                            TABLE 4

      DISTRIBUTION OF PORTLAND CEMENT PLANTS BY CAPACITY
Rated Annual
(thousands of
metric tons)
0-270
270-455
455-910
over 910
Capacity
(thousands of
short tons)
0-300
300-500
500-1000
over 1000
Number of
Plants
31
56
66
13
166
Percent
of Total
Plants
18.7
33.7
39.7
7.9
100.0
Percent of
Industry
Capacity3
7.4
24.0
47.6
21.0
100.0
a.  Total rated annual capacity of industry is 86-million
    metric tons (95-million short tons).

Data derived from RAPP applications, questionnaires, and
  industry publications.
                            -17-

-------
Wet Process
.
\
Proportioning
and Mixing of
Raw Materials
in Slurry Tanks
"j

Grinding « — Vv
1

Homogenizing
and Blending
i
Ki

Evaporati
t

In


Raw Materials
I
I Crushing 1
I
~ Water
fater
on 	
/KilnX '
/ Dust \
*""Vsee Fig- /
V ure 5 ) /
*


1
Finish
Grinding and ^
Gypsum
Ad^i^iQn
1
Cement Cooler
I
Storage
Bagging
Shipping
Dry Process
1
Proportioning
and Mixing of
Raw Materials
1
Grinding
1
Homogenizing
and Blending
i




_^ Clinker
Storage


Figure 4.  Flow Sheet for the Manufacture of
               Portland Cement

                     18

-------
frequently determines which process a plant will use.  For  example,  if
clay  and  marl with a high water content are available, the wet process
may prove more economical.

After the raw material has been finely ground it is  placed  in  storage
containers—silos for dry process and slurry tanks for wet process.  The
material  is  analyzed  and  the composition is adjusted as necessary to
obtain the correct formulation for the type of cement being produced.

The ground raw materials are  fed  to  a  kiln  consisting  of  a  large
rotating  metal tube, usually 3.7 m(12 ft) or more in diameter and 75 to
150 m (250 to 500 ft) long, lined with refractory brick on  the  inside.
The  kiln  is  inclined  slightly  so  that the contents are transferred
forward as the kiln  rotates.   The  raw  materials  are  fed  into  the
elevated  end,  and  the kiln'is heated by a flame at the lower end.  An
array of heavy steel chains near the  entrance  is  used  sometimes  and
serves to transfer heat from the gas stream to the raw materials.

The  fuel for the kiln may be coal, gas  or oil.  Most cement plants are
equipped to burn more than one type of fuel, and the fuel  used  at  any
particular  time  is  dictated by availability and cost. When available,
natural gas is usually the  least expensive fuel, but in order to obtain
gas at the most favorable price, the manufacturer must agree to  curtail
its  use when supplies are limited, and must, therefore, use coal or oil
as a standby fuel.

The amount of fuel used to manufacture cement varies with the efficiency
of the kiln, the composition of raw materials,  the  process  used,  and
many other operational factors.  In 1963, on the average, the production
of  one  metric  ton of cement required about 2U6 kg(541 Ib) of coal, or
187  cu  m  (6670  cu  ft)  of  natural  gas  which  is  equivalent   to
approximately  1.5 million kg cal. (5.8 million BTU). (29)   Newer plants
would be expected to consume about 2Q% less  fuel.   Although  the  wet-
process  kiln  has  a higher heat requirement than the dry-process kiln,
the fuel consumption difference, in many cases, is partially  offset  by
the  heat  consumed  in those dry-process plants in which dryers precede
the raw materials grinding.

As the raw materials proceed down the kiln their  temperature  increases
to about 1600°C (2900°F).  At this temperature the raw materials reach a
point  of incipient fusion and hard,  marble-sized balls, called clinker,
are formed As the clinker comes from the kiln it is  rapidly  cooled  by
air (part of which is subsequently used as combustion air in the kiln).

The  clinker  along  with a small amount of gypsum added to regulate the
setting time is ground into a  fine  powder.   The  grinding  energy  is
dissipated as heat in the product, and the cement is cooled before being
bagged  or  shipped  in  bulk  to  the  user.  One type of cement cooler
consists of a large, vertical cylinder with a rotating screw that pushes
                                  19

-------
the cement through the cooler.  The heat  is  removed  by  water,  which
flows  through  an  enclosed jacket around the cooler or cascades in the
open down the outside.

The finely ground cement is transported within the  plant  by  pneumatic
pumps.   The air is supplied by water cooled compressors.  After the air
has been used to convey the cement it is cleaned with bag  filters,  and
the  dust  removed  is  returned  to the product stream.  In dry-process
plants much dust is associated with the grinding and  pneumatic  pumping
of  raw  material.   This  dust  can also be collected in bag houses and
returned to the process.


Kiln-Dust^Considerations

Because of its impact on the environment, the collection arid disposition
of kiln-dust deserve special consideration.

The greatest source of dust at most cement plants is from the kiln.  The
rotation of the kiln plus the rapid flow of gases (from the evolution of
carbon dioxide from the raw materials)  and  the  motion  of  the  chains
cause  a  large amount of the finely ground material to become airborne.
The high-velocity gases flowing through the kiln carry large  quantities
of  this dust (typically 10 to 20% of the kiln feed) out of the feed end
of the kiln.  The large dust particles can be removed from the gases  by
mechanical collectors (cyclones), but the smaller particles require more
expensive  dust collectors  (electrostatic precipitators, bag filters, or
wet scrubbers).   Reuse  of  collected  dust,  if  compatible  with  the
process,  is  advantageous  from three points of view -- conservation of
raw  materials,  reduction  of  disposal   costs,   and   reduction   in
accumulation of solid wastes.

There are two ways to return collected dust to the kiln.  In some plants
the  dust is mixed with the raw feed.  In other plants the clust is blown
in through a pipe in the hot end of  the  kiln,  a  technique  known  as
insufflation.   A portion of the dust is often wasted to prevent buildup
of a large amount of fine particulate  matter  containing  alkali  salts
that continuously cycles between dust collector and kiln.

The dust that is removed from the kiln gases by the dust collectors is a
mixture  of  particles  of  raw  material,  clinker,  and  materials  of
intermediate composition.  The gases  also  contain  alkalies  from  raw
materials  and  fuel  that are volatilized in the hottest portion of the
kiln and condensed into a fume as the gases  passed  through  the  kiln.
The  alkalies in the raw material are insoluble because they are tightly
bound in a mineralogical matrix.   The  high  temperature  in  the  kiln
alters  the matrix sufficiently to free a large portion of the alkalies.
The free alkali is volatile at high temperatures, and it is  also  water
soluble.
                                  20

-------
A.S.T.M.  and  Federal specifications require that the alkali content of
certain cement products not exceed 0.6%.  The  low-alkali  specification
is  only  necessary in cases of known or suspected alkali reactions with
the aggregate being used, but many building and construction contractors
routinely specify low alkali cement regardless of the characteristics of
the aggregate.  Therefore,  since  many  manufacturers  have  difficulty
marketing high-alkali cement, they strive to make a low alkali cement as
a  standard  product.   For  plants  that  use raw materials with a high
alkali content, the

dust cannot be returned directly to the kiln, and its reuse and disposal
constitute a serious problem in the industry.

As air pollution control regulations have  become  more  stringent,  the
amount  of high-alkali dust that is collected has increased, and as more
manufacturers install dust collectors that remove more than 99%  of  the
particulate  load from the stack gases, the problem of disposal of high-
alkali  dust  will  increase.   Measures  to  minimize  water  pollution
stemming  from  increased  amounts  of high-alkali dust are described in
Section VII.

Figure 5 shows a schematic of  the  kiln-dust  collection  and  handling
systems currently employed in the industry.

Table  5  summarizes  the  methods  employed  to dispose of kiln dust as
reported by 80 plants.  As shown in the Table, only 27  (34?4)   of  these
plants are able to return all of the collected dust to the kiln.

Presently  most  manufacturers  are wasting the collected kiln dust that
cannot be returned to the kiln.  The dust is hauled or  slurried  either
to  an  unused part of the quarry or to vacant land near the plant.  The
presence of the  dust  limits  the  future  use  of  the  dumping  site.
Moreover,  leaching  of  the  dust  piles  by  rainwater  overflow  from
slurrying can cause pollution of streams and ground water.

To avoid wasting high-alkali dust,  some  manufacturers  have  installed
kiln-dust  leaching  systems.  The dry dust is mixed with water in a pug
mill to  make  a  slurry  containing  about  10%  solids.   The  soluble
alkalies,  usually  at  least  half  of  the alkali content, immediately
dissolve.  The slurry flows into a clarifier where  the  solid  material
falls  to the bottom.  The underflow from the clarifer which contains 40
to 60% solids is returned to the kiln.  The overflow, which contains the
alkalies is discharged.  This  discharge  constitutes  the  most  severe
water pollution problem in the industry.

Another  alternative is to use only raw materials of low alkali content.
Many cement manufacturers do not have a dust  disposal  problem  because
their  quarries  centalr   low-alkali raw materials.  However, the alkali
content of the raw mateiials is only one of the many factors  that  must
                                  21

-------
Kiln Dust
i
< ' 1 1
Electrostatic _ , _.
Precipitator Cyclone Bag House
1 1 I

Dust Bin
,
I , 1
Return Pile, Bury, Mixed with
to Kiln or Haul Water to *—
Form Slurry
Overflow Recycled



OC.4-+-1 -i n(-r _ Leaching
oet-UJ-J-ny (Overflow nasin
Pond * '
(Thickener)
1 4

Neutralization

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>
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Make-
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Water


Underflow
» Returned
to Kiln


scharge
                  Discharge




Figure 5.  Kiln Dust Collection and Handling
                      22

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                                                   DRAFT

                           TABLE 5

    SUMMARY OF METHODS OF DUST UTILIZATION AND DISPOSAL


                                Number of        % of 80 Plants3
	Method	    Plants Reporting       Reporting

All dust returned to kiln          27                  34

Surface piling (dry)               29                  36

Returned to quarry  (dry)           11                  14

Leached                             9              -    11

Slurried and discarded              7                   9

Some sold or hauled
  away by contractor                8                  10
a.  Percentage total is greater than 100 because some
    plants report more than one method.

Data derived from RAPP applications, questionnaires, and
  plant visits.
                            23

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be  considered in selecting a plant site,  and many of the present cement
plants were constructed long before alkali problems became  significant.
Cohrs  (20)   made  a survey of 30 plants built since 1960 and found that
only ten had anticipated dust disposal problems  prior  to  construction
and  had  made  plans to handle it.  In some cases plants have hauled in
low-alkali raw materials to avoid a  dust  disposal  problem,  but  most
plants would find this solution economically prohibitive.

Since  waste  kiln  dust  has  a high potassium content and considerable
capacity for neutralizing acids, suitable uses  for  the  material  have
been  proposed.   Some of the applications that have been, considered are
fertilization, soil stabilization, and neutralization of  acidic  wastes
from  metal  pickling  operations and mine drainage.  Although such uses
for waste dust have been pursued for many years, most of  the  dust  now
being collected is discarded.
                                  24

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                               SECTION IV

                        INDUSTRY CATEGORIZATION


                              Introduction

In   developing   effluent   limitations  guidelines  and  standards  of
performance for new sources for a given industry,  a  judgment  must  be
made  as  to  whether  separate  effluent  limitations and standards are
appropriate for different segments (subcategories)  within the  industry.
The  appropriateness  of  potential  subcategories  for the cement manu-
facturing industry was evaluated on the basis of inherent differences in
the  characteristics  and  treatability  of  the  effluent  from  plants
segmented with respect to the following features.

     Method of Dust Collection and Disposition

     Type of Process  (Wet or Dry)

     Plant Age

     Plant Size

     Raw Materials

     Type of Fuel

     Auxiliary Operations

     Products Produced

     Plant Location

As  a  result of an intensive study of the wastewater characteristics of
about 80% of the 166 plants in the industry, and an  evaluation  of  the
technology  available  for  control and treatment of these wastes, it is
concluded that the cement manufacturing industry should be divided  into
two subcategories based upon the method employed for dust collection and
disposition.

Factors_Considered

Method of Dust Collection and Disposition

All  cement  plants  collect  large amounts of kiln dust and must either
reuse it or discard it.  As discussed in  Section  III,  if  the  alkali
content  is  too  high for direct return to the kiln, the dust is either
leached or wasted.
                                  25

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Whether wasted by means of wet slurrying to a pond  or  by  dry  piling,
contamination  of surface waters can result from overflow of the pond or
runoff from  rain.   Adequate  methods  of  controlling  or  eliminating
discharges from these sources are available.

In  leaching  operations,  large volumes of water are generally involved
and the waste loadings are much higher than in  nonleaching  plants,  as
shown  in  Figure  6.   At the present time, no practical and completely
effective methods of  treating  this  water  for  reuse  are  available.
Plants  that  use  wet  scrubbers for the collection of kiln dust employ
even larger quantities  of  water,  which  may  become  contaminated  by
soluble materials.

Thus,  based  on  the  significant  differences  in  waste  loadings and
treatability of the wastewaters, two subcategories are defined:

     ~ leaching plants, in which the kiln dust comes into
       direct contact with water in the leaching of kiln
       dust for reuse or in the wet scrubbing of dust to
       control stack emissions.

       nonleachinq plants, in which contamination of water is
       not inherently associated with the water usage.

Type of Process

As described in  Section  III  of  this  report,  there  are  two  basic
processes  for  the  manufacture  of portland cement: the wet process in
which the raw materials are slurried with water before being fed to  the
kiln  and  the dry process in which the raw materials are ground and fed
to the kiln without use of water.  A review of  the  characteristics  of
the wastewater and inspections of both types of processes, indicate that
the  type of process need not have a direct effect on the quality of the
wastewater.  Table 6 shows  the  average  loading  of  several  selected
parameters  for  wet- and dryprocess plants and the percentage of plants
of each type that report less than 0.005 kg per metric ton  (0.01 Ib/ton)
of cement produced.  The average loadings  for  wet-process  plants  are
slightly greater, due to the high loadings of the leaching plants.
                                  26

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                                                                         D
       Alkalinity
  Total
Dissolved
  Solids
  Total
Suspended
  Solids
Sulfate
Potassium
          Figure   6.  Comparison of Loadings of Selected Parameters
                     for Leaching and Nonleaching Plants
Data derived from 88 RAPP  applications.
                                   27

-------
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                               28

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almost  all  of  which are wet, but the average is still relatively low.
Moreover, a significant number of plants in both groups report very  low
loadings.

As discussed in Section VII, the two different processes offer basically
different  options  for water management and reuse.  However, acceptable
options are available for both types of processes.  Any difference  that
may exist in the cost of implementing these options is likely to vary as
much  among  plants  of  the  same  type  of  process as among plants of
different types of process.  Therefore, wet- and dry-process plants  may
be included in either subcategory.

Plant Age

Portland  cement  plants range in age from 2 years to more than 75 years
since initial plant start-up.  Analysis of the reported  start-up  dates
for  plants  representing  75%  of  the  establishments  in the industry
indicates that 16% of the plants are less than 10 years old while 37% of
the plants are less than 20 years old, and about 32% of the  plants  are
more  than 50 years old.  Analysis of the quantity of water used and the
wastewater constituents with respect to plant age shows  no  correlation
between  plant age and either the volume of water used or the wastewater
characteristics.  There are probably two basic reasons for this lack  of
correlation:   first,  the basic process for the manufacture of portland
cement has changed little in the  last  50  years;  and  second,  cement
plants  in  general are constantly undergoing updating and modification.
Thus, a plant that was constructed in 1906 may be operating  with  kilns
and   other  equipment  that  are  identical  to  those  in  a  recently
constructed plant.  Therefore, plants of different ages may be  included
in either subcategory.

Plant Size

Analysis of the available data and inspection of plants of various sizes
indicate that there is no correlation between plant size and the quality
of  wastewaters  as  shown  in  Table 7.  The lowest and highest average
values  for  alkalinity  and  total  solids  are  within  one   standard
deviation.  Also  shown  in the table are the gross water discharged and
the water discharged per ton of product, which  vary  widely  among  the
large  and  small  plants  with  no  obvious relationship to plant size.
While  a  smaller  plant  may,  through  water  conservation  and   good
management  practices, consume and discharge far less water, this is not
necessarily the case.  Differences in the amount of water discharged and
possibly requiring treatment may be reflected in higher costs of control
and treatment  technology;  however,  since  such  differences  are  not
directly relatable to plant size, plants of all sizes may be included in
either subcategory.

Paw Materials
                                  29

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As  discussed  in  Section  III,  the  raw  materials  required  for the
manufacture of portland cement are  chemically  similar,  including  the
oyster  shell  used  at  a small number of plants located along the Gulf
Coast.  Analysis of the available data and on-site studies of  exemplary
plants indicate that with the exception of alkali content, which will be
discussed  below,  only  minor differences in the quantity or quality of
wastewater may be related to the type of raw materials used.

The raw  materials  that  are  available  to  some  plants.   especially
 limestone and clay, may contain higher-than-average amounts of potassium
and sodium.  These differences  will  be  reflected  in  the  wastewater
streams  only  at those plants where the kiln dust comes in contact with
the waste stream.  Plants where such contact is purposeful  rather  than
incidental  have  already  been  considered  as  a separate subcategory.
Thus, the type of  raw  material  is  considered  with  respect  to  its
influence on dust handling techniques, and as such is covered in the two
selected subcategories.

Fuel

Few  plants  use  only  one  type  of fuel.  The type of fuel burned may
affect the amount of water-soluble constituents in the  kiln  dust;  and
minor  differences  may  be  found  in the wastewater characteristics of
plants using different fuels, if the kiln-dust comes in contact with the
water.  These differences are considered in the  defined  subcategories.
Leaching  of  coal  piles  by  rainfall  and  subsequent runoff may be a
problem at some  coal-burning  plants,  however,  adequate  methods  for
controlling  such  runoff  are  available  in other industries that have
large coal storage piles.  Such methods include spraying the piles  with
latex  films  that  prevent moisture from entering the piles, and diking
the coal-pile combined with lime or limestone neutralization to  prevent
discharge of acidic run-off water.

Ancillary Operations

A.S  discussed  in  Section III, cement plants may conduct activities not
directly concerned with  the  manufacture  of  portland  cement.   These
activities  include the generation of electric power from boilers heated
by waste kiln heat, the washing of bulk hauling trucks, the cleaning  of
slurry  tanks,  the blowing-down of cooling towers, air compressors, and
boilers, and the beneficiation and washing of raw material.

Power generation by waste-heat boilers is limited to only a few  plants.
While  this  operation could provide a basis for separate consideration,
pollutants in waters arising from  this  activity  are  intended  to  be
covered  by  effluent  guideline  document  and  regulations promulgated
separately at a future date by EPA.
                                  31

-------
The other activities are practiced to some extent at  most  plants,  and
the  characteristics  of  wastewaters  arising  from such activities are
common to the industry as  a  whole  which  precludes  consideration  of
auxiliary operations as a basis for subcategorization.

Products Produced

Different  types  of  portland cement are produced by either varying the
raw material mix and manufacturing conditions or blending additives with
the cement after the clinker has been  ground.   There  are  only  minor
variations  in  the manufacturing process for making different products.
Several types of products may also be made at  different  times  at  the
same  facility.   With  the exception of low-alkali cement produced from
high-alkali raw materials, the general waste characteristics will be the
same, irrespective of the type of  cement  being  produced.,    Low-alkali
cement  production  affects water quality only at leaching plants and is
thus already considered.

Plant Location

Wastewater quality was not found to be related to geographical location.
Some variation may exist in  regions  of  the  country  where  the  only
available  raw  materials  are  highly  alkaline,  but,  this factor was
considered under raw materials.  Thus, geographical location  is  not  a
suitable basis for subcategorization.

The  local  topography  as  reflected  by the availability of land or an
adjacent  quarry  that  may  be  used  for  wastewater  disposal  varies
considerably  from  plant  to  plant.   However,  since  other  options,
discussed in Section VII,  are  available,  topological  considerations.
are not a reasonable basis for subcategorization.
                                  32

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                               SECTION V

                  WATER USE AND WASTE CHARACTERIZATION

General

The  operations  where  the  largest volumes of water are used in cement
plants are essentially non-polluting.  Process water in  wet  plants  is
evaporated;  most  cooling water is not contaminated; the change usually
noted is an increase in temperature.

Any contaminated discharges contain constituents that are present in the
raw materials, collected kiln dust, or cement dust.  These constituents,
which include aluminum, iron,  calcium,  magnesium,  sodium,  potassium,
sulfate,  and  chloride,  may  occur  in any water that has contact with
these materials.

The presence of these constituents will be reflected as total  dissolved
solids, total suspended solids, and high pH and alkalinity.

Other  constituents,  reported  as  BOD,  COD,  Kjeldahi nitrogen, total
volatile solids, and phenols, have been noted in the effluents  of  some
plants.  However, these are related to the presence of organic materials
not  directly  related to the process of cement manufacture, but arising
from sanitary effluents, spills of fuel oil, runoff from coal piles, and
drainage from quarries, settling ponds  and  cooling  ponds,  which  may
contain decayed vegetation.

Plants  in the leaching subcategory have a higher pollutant loading than
other plants.  This is  illustrated  by  the  average  loading  for  six
selected  parameters  in  Figure  6 and for 35 parameters reported in 88
RAPP applications in Table 8 for plants in both subcategories.

SpecificWater^Uses and Waste^characteristics

Water usage for the cement industry is summarized in Table 9 and in  the
flow  diagrams  in  Figure 7.  These uses and the characteristics of the
associated discharges are discussed below.
Cooling Water

The major use of water at most cement plants is for cooling.  This water
is used to cool bearings on the kiln
                                  33

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-------
Intake
 Water
     100 1/kkg Raw.  Mat.
           Cooling
           Cooling
      Dust
     Contact
             Raw Material
              Washing and
             Beneficiation
     2060 1/kkg Product
            Mill Bearings

            Kiln Bearings

            Burner Pipes

            Cement Cooler

            Air
             Compressors
     340 1/kkg Product
     	Process	

      (wet plants only)
      860 1/kkg Product


        Dust Control

      264,000 I/day
               Collection
             Clinker
              Cooler
             Kiln-Gas
              Cooling
               Slurry
             Truck Washer
            Road Spraying
                             Wet Scrubber
28,000
 1/kkg Product

Leaching
                     1/kkg
                 Dust

                 Disposal
                              Clarifier
                                                      Recycle,
                                                       Reuse,  or
                                                        Discharge
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                   1/kkg
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                             Settling
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                                       Discharge
            Figure  7.  Diagram of Water Usage in Cement Manufacturing,

                                   36

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                                   TABLE 10

                REPORTED COOLING WATER USAGE IN CEMENT PLANTS


                              Average Flow,       Number of    	Range	
	Use	    1/kkg (gal/ton) Product    Plants      Minimum    Maximum

 Bearing cooling               1,080 (284)           39        3.8 (1.0)  5,800 (1,530)

 Cement Cooling                  760 (200)           22        1.9 (0.5)  3,750 (985)

 Clinker cooling                  60 (23)            12        2.1 (0.6)    242 (64)

 Kiln-gas cooling                322 (85)             4         92 (24)     770 (203)

 Bucner-pipe cooling             265 (70)             2        258 (68)     272 (72)
 Data derived from 39 questionnaires.
                                       37

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and grinding equipment., air compressors, burner pipes and  the  finished
cement  prior  to  storage or shipment.  A summary of average volumes of
cooling water used for specific purposes is given in Table 10.

While cooling water is mostly non-contact, it can become contaminated to
some extent through poor water management practices.  This contamination
may include oil and grease, suspended solids, and  even  some  dissolved
solids.   If  cooling  towers are used, blow down discharges may contain
residual algicides.

Process Water

For purposes of this discussion, process water is defined as the  slurry
water  used  at  wet  plants to feed the raw material to the kiln.  This
water is subsequently evaporated in the kiln and,  therefore,  does  not
constitute a discharge.

The  relatively  constant  volume  of  water  used in the preparation of
slurry averages 860 1/kkg (260 gal/ton).
At a few  plants,  excess  water  containing  a  high  concentration  of
suspended  solids  is  discharged  from  the  slurry  thickeners.   This
practice constitues a non-essential discharge and is easily  avoided  by
recycling  this water for making the slurry.  Other losses of slurry may
occur due to poor maintenance of pumps, which become  worn  and  develop
leaky  seals.   The  resulting  spillage may result in a waste discharge
with high solids if not controlled.

Kiln-Dust-Contact Water

There are three operations in which water contacts collected kiln  dust.
The wastewater generated by plants with these operations constitutes the
highest loadings of pollutants within the industry.

The  most  significant  of these operations is the leaching  (removal) of
soluble alkalies from the  collected  dust  so  that  the  dust  may  be
returned  to  the kiln as recovered raw material.  This operation occurs
at about nine plants.  In all cases the overflow   (leachate)  from  this
operation  is  discharged, sometimes without treatment.  The wastewaters
from this operation are essentially identical for all plants, varying to
some extent in the concentration of individual constituents  because  of
differences  in raw materials at each plant.  These constituents include
high pH, alkalinity, suspended solids, dissolved solids, potassium,  and
sulfate.

The  second  most common operation is the wet disposal of dust.  In this
operation a slurry is also made of the collected kiln dust and fed to  a
pond, where the solids settle out.  The settled solids are not recovered
for  return  to the kiln, and the overflow  (leachate) may be discharged.
The constituents of this discharge are essentially  the  same  as  those
                                  38

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from  the  leaching operation.  At least five plants use this wet method
to dispose of collected kiln dust and the volume of  water  used  ranges
from 70,000 to 760,000 I/day  (18,000 to 200,000 gal/day).

The use of wet scrubbers for air pollution control constitutes the third
example  of  water in direct contact with the kiln dust.  At least three
plants in the industry use wet  scrubbers  to  collect  kiln  dust  from
effluent gases.

Other Water Uses

All  cement  plants  have some accumulation of settled dust on the plant
property and this dust may show up in the  wastewater  in  a  number  of
ways.   Many  plants  spray  water on the roads to prevent the dust from
becoming air-borne by truck traffic.  Most plants  also  routinely  wash
accumulated  dust  off the trucks.  At some plants, certain parts of the
plant areas are also washed down to remove accumulated dust.  The amount
of water used for these purposes varies widely, ranging from 950 to 9500
I/day  (250 to 2500 gal/day) as reported in a sample of 12 plants.   Some
of this water undoubtedly evaporates, but depending on the topography of
the  plants,  some  of this water may drain into storm sewers or natural
waterways.

Water from surface runoff after rain may also be  laden  with  the  dust
that accumulates on the plant site.  Runoff from dust piles, coal piles,
and  raw  material  piles  may  also  become  contaminated.  Plants with
boilers, cooling towers,  and  intake  water-treatment  facilities,  have
blowdown and backwash discharges associated with these operations.

At some plants, raw materials are washed and at others the raw materials
are  encriched by a beneficiation process; these processes may result in
wastewater discharges containing suspended solids.

Where an active or abandoned quarry is used as  a  receiving  basin  for
dust  disposal or plant wastewater, the discharge from the quarry may be
contaminated with wastes associated with cement manufacturing.  However,
where a quarry is used exclusively for the production of  raw  material,
discharge  of  any  accumulated  water (dewatering) if not considered in
this report and is intended to  be  considered  in  the  Mineral  Mining
Industry  Effluent Guidelines Study.  For nonleaching plants the average
net loading of suspended solids is less than zero, indicating that  more
solids  are  removed  from  the  intake water used in the plant than are
added by the process.  However, 4 of the 58 plants of this group  report
over  1  kg/kkg  (2  Ib/ton)  of  product indicating a moderate level of
suspended solids is possible if not properly controlled.

For leaching plants the average discharge of  suspended  solids  is  0.9
kg/kkg  (1.8 Ib/ton) of product.
                                   39

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                               SECTION VI
                   SELECTION OF POLLUTANT PARAMETERS


Definition^ of Pollutants

Section  502  of  the  Federal Water Pollution Control Act Amendments of
1972  defines  pollution  as  "...the  iran-induced  alteration  of   the
chemical,  physical,  biological,  and  radiological  integrity  of  the
water."  The term pollutant is defined as  "industrial,  municipal,  and
agricultural waste discharged into water."

For  purposes  of  this  report  pollutants  are  defined  as  chemical,
physical, or biological constituents of discharged water that are  added
in  quantities  measurable by routine analytical procedures greater than
0.005 kg/kkg  (0.01 Ib/t) of product as a result of the water being used
in manufacturing operations characteristic of the industry.  For a plant
with a discharge flow of 8.3 million liters per day  (2.2  mgpd)   and  a
daily  production  of  1420  kkg/day (1560 t/day) average values for the
industry, a loading of 0.005 kg/kkg of product  would  correspond  to  a
concentration of less than 1 mg/1.

At  some  plants,  other  constituents  may  be  added  as  a  result of
operations that are not unique  to  the  industry,  but  are  considered
pollutants  as defined in the Act.  Pollutants from these sources may be
subject to limitations on an individual plant basis, or  to  limitations
developed for other point sources.

Pollutant^Parameters

Based on information on 35 parameters,  listed in Table 8, as reported in
the  RAPP  Applications  of  88  plants and analysis of wastewater at 10
plants, seven constituents have been identified as  pollutants  for  the
cement industry.  These constituents are present in the waste streams of
plants  in  both  subcategories  and  are  subject  to  the  limitations
recommended in this report.  Table 11 presents the relevant data on each
of these parameters, listed below, for plants in both subcategories.
                                  41

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1.  pH

2.  Total dissolved solids

3.  Total suspended solids

4.  Alkalinity

5.  Potassium

6.  Sulfate

7.  Temperature


Rationale for Selection of Specific Parameters as Pollutants

PH

Because of the water soluble  alkalies  in  cement  dust,  any  effluent
contaminated  with  dust  will  have  an alkaline pH.  Average pH values
range from 8.2 for nonleaching plants to 9.9 for plants in the  leaching
subcategory.  Figure 8 shows the distribution of maximum reported pH for
88 plants.

Total Dissolved Solids

Dissolved  Solids  are present in effluent waters that have contact with
dust.  Average loading of dissolved solids is 0.27 kg/kkg  (0.54  Ib/ton)
of  product  for  nonleaching  plants  and  6.6 kg/kkg  (13.2 Ib/ton) for
leaching plants.

Total Suspended Solids

Since cement dust is dense and tends to settle  out  rapidly,  suspended
solids  may  be  removed  from  the wastewaters before leaving the plant
property.

For nonleaching plants the average net loading of  suspended  solids  is
zero.  However, 4 of the 58 plants of this group report over 1 kg/kkg  (2
Ib/ton)  of  product  indicating a moderate level of suspended solids is
possible, if not properly controlled.

For leaching plants the average discharge of  suspended  solids  is  0.9
kg/kkg (1.8 Ib/ton) of product.

Alkalinity
                                  42

-------
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43

-------
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8      9      10    11

 Reported Maximum pH
                                                   12
13
           Figure 8.  Distribution of Reported Maximum pH
                               44

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Because  of  their  highly  buffered  nature,  the effluents from cement
plants can  have  a  relatively  low  pH  and  still  have  considerable
alkalinity.   The  average loading for nonleaching plants is 0.09 kg/kkg
(0.18 Ib/ton)  of product.

For leaching plants the average loading  is  considerably  higher,  1.38
kg/kkg (2.8 Ib/ton)  of product.

Potassium

Where   potassium   is  present  in  the  raw  material  in  appreciable
quantities, it will be the major soluble alkaline component of the  kiln
dust  collected  in  air  pollution  control equipment.  Thus, potassium
salts will be found in water that has contact with the  collected  dust.
This  is  confirmed  by  the fact that leaching plants report an average
loading of 3.3 kg/kkg (6.6 Ib/ton)  while other plants report 0.08 kg/kkg
(0.16 Ib/ton).

Sulfate

Sulfate is present in the raw materials and some  additional  quantities
may  be formed in the kiln, at plants that burn sulfur-containing fuels.
Average net loadings of sulfate are zero for nonleaching plants and  6.7
kg/kkg (13.4 Ib/ton) for leaching plants.

Temperature

Since  all  cement plants use cooling water, a temperature increase is a
characteristic of the effluent  of  most  cement  plants.   Because  the
quantity   of  water  used  for  cooling  varies  considerably,  and  is
distributed  among  a  number  of  streams,  the  thermal  pollution  is
calculated  in  terms  of  actual  heat  generated (cal/kg of product or
BTO/ton)  by dividing the increase in temperature by the daily production
and multiplying by the daily flow and an appropriate constant.  In these
terms, the average thermal increase reported by 63  plants  is  4800  kg
cal/kkg  (17,200 BTU/ton) + 4150 kg cal/kkg  (14,900 BTU/ton)  of product.
These numbers may be back-calculated using the average  daily  flow  and
production  to  give  a  typical  temperature  increase  of 3°C (5.5°F).
Eleven plants report a t.ypical increase from 6 to  11°C   (10  to  19°F) .
Figure 9 shows t.he calculated average temperature rise for 65 plants.

At  some  plants  in  the  cement  industry,  thermal  pollution must be
considered as a significant parameter.

Rationale for Rejection of Specific Parameters as Pollutants

The following constituents were considered, but  were  not  selected  as
pollutants for the reasons indicated:
                                  45

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                       Rise.
      Data derived from 88 RAPP applications.
                                     46

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BOD, Kjeldahl nitrogen, phenols, total organic carbon

These  constituents  are  reported  in  the  discharges  for some cement
plants.  However, their occurence is  associated  with  nonmanufacturing
discharges,  such  as  sanitary  effluent  and drainage from quarries or
ponds where organic material could be present.  Since they  are  largely
identified with organic materials not associated with the manufacture of
cement,  they  are  not  considered  pollutants  characteristic  of this
industry.  The average loading of each of  these  constituents  is  less
than 0.005 kg/kkg  (0.01 Ib/ton).

Calcium, magnesium, sodium, aluminum, iron

These  constituents  are  present  in  both  the  raw  materials and the
finished  product;  consequently  they  are  sometimes  found   in   the
wastewater  generated  by  cement  plants.   sodium and calcium are more
prevalent in dust-contact streams.  Since the  presence  of  sodium  and
calcium will be reflected in the level of alkalinity and total dissolved
solids,   they  will  be  indirectly  measured  and  controlled  by  the
limitations on these parameters.

Aluminum and iron compounds are  normally  found  only  in  dust-contact
streams  and  at  relatively  low  loading  levels  and  are included in
consideration of total suspended solids and total dissolved solids.

Heavy metals (lead, chromium, cadmium, mercury, nickel, copper)

With the exception of lead and chromium, significant loadings  of  heavy
metals  have  not been detected in the wastewaters for the industry.  In
an apparently isolated case, lead  is  reportedly  associated  with  the
discharge  of  a  single plant that uses oyster shell.  Chromium is only
present in the discharge of a few plants from non contact cooling  water
systems.

Turbidity, total hardness, total solids, total volatile
solids, COD

These parameters are present in the wastewaters of the industry, but are
more  accurately  covered  by inclusion with the parameters of suspended
solids, dissolved solids and alkalinity.

Oil & grease, ammonia, nitrate  (as N) , phosphorus (as P) ,
sulfide, sulfite, fluoride, zinc

These constituents are not normally  present  in  the  wastewaters  from
cement  plants.   Oil  and  grease can occur from leakage of bearings in
cooling-water streams.  However, the average loading  of  this  and  the
other  parameters  in this group is less than 0.005 kg/kkg (0.01 Ib/ton)
of product for the industry.
                                  47

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                              SECTION VII

                    CONTROL AND TREATMENT TECHNOLOGY


Introduction

There are relatively few operations in cement  manufacturing  where  the
addition  of  pollutants to the water used is inherently associated with
the use of that  water.   For  most  of  the  plants  in  the  industry,
pollution results from practices that allow materials to come in contact
with the water.  Pollutant levels at these plants can be greatly reduced
or  eliminated by suitable in-plant control measures that prevent wastes
from entering the water or by more extensive  reuse  and  recycling*  of
water that may become contaminated.

For  the  plants  in  the  leaching  subcategory, wastes are necessarily
introduced into the water and recycling  is  not  feasible.   Thus,  for
these  plants,  treatment  is  required to reduce the pollutant loading.
Only a limited improvement can  be  expected  from  the  application  of
 available  control technology.   The main control and treatment methods
for the cement industry involve recycle and reuse  of  wastewater.   The
devices  employed  include cooling towers or ponds, settling ponds, con-
tainment ponds, and clarifiers.  Cooling towers or  ponds  are  used  to
reduce  the  temperature  of  waters  used  to  cool  process equipment.
Settling ponds  are  used  primarily  to  reduce  the  concentration  of
suspended  solids.   Containment ponds are used to dispose ot waste kiln
dust.  Clarifiers are mainly used to separate  solids  in  dust-leaching
operations.

With  the exception of plants in the dust-contact subcategory, both wet-
process and dry-process plants can achieve virtually complete  reuse  of
wastewater with existing state-of-the-art technology.

*In  these  discussions  recycle means using again for the same purpose;
whereas, reuse means to recover for another use.

With respect to wastewater management, wet-process  cement  plants  have
features  that  iistinguish them from dry-process cement plants.  In all
wet-process plai~s, except for those  that  leach  collected  dust,  the
wastewaters  from  sub-processes (e.g.plant clean-up, truck washing, and
cooling) and storm runoff waters, can  be  used  in  the  raw  mills  to
prepare  the  slurry  fed  to  the  kiln.   In  the  kiln  the  water is
evaporated, any inorganic matter in the water enters  the  product,  and
any organic matter in the water is burned.  Thus, for wet-process plants
complete  reuse  of  wastewaters  is possible, although in some existing
                                  49

-------
plants installation of cooling towers  or  ponds  may  be  necessary  to
permit recycling of excess cooling water.

In  contrast  to  the practices possible in wet-process plants, for dry-
process plants disposal of wastewaters from sub-processes in  the  kilns
is  not  possible.   Nevertheless,  a  number of dry-process plants have
achieved virtually complete recycle of wastewaters by the employment  of
cooling  towers  or  ponds.  The only discharge from these plants is the
small volume of "blow-down" or "bleed" water from cooling towers that is
required to prevent buildup of dissolved solids in  the  cooling  water,
and  where  contaminated,  these  small volumes can be evaporated at low
cost.

Even without  recycling,  control  measures  can  be  taken  to  prevent
introduction  of  contaminants  into  the water effluent from the plant.
Cooling  water  streams  can  be  segregated  from  other  streams,  and
precautions  can  be taken to avoid entry of dust into the cooling water
circuit.

In-Plant JTontrol^Measures

In-plant measures are primarily  limited  to  the  control  of  nondust-
contact  streams.   For  plants within the leaching subcategory, control
technology consists of segregation of the leaching  streams  from  other
plant discharge streams and conservation of water to minimize the volume
of water requiring treatment.

Control  technology applicable to non-contact streams is discussed below
for the major water uses  and  potential  sources  of  wastewater.   The
individual plants referred to are discussed in detail at the end of this
section.

Cooling Water

In  either  wet-or  dry  process  cement  plants,  water is used to cool
process equipment such  as  bearings,  compressors,  burner  tubes,  and
cement coolers by non-contact heat exchange.  The wastewaters from these
cooling  operations are hotter than the entering water.  The temperature
rise in waters used to cool bearings is normally  small,  and  desirably
low  temperatures  can  often  be achieved by a simple recycle system in
which heat is lost to the atmosphere from a small amount of  pipe  or  a
package recycle system as is the practice at Plant A.  In waters used to
cool  compressors, burner tubes, or cement coolers, the temperature rise
is larger.   However,  if  the  temperature  of  cooling  wastewater  is
reduced,  the  waters  may  be recycled.  Temperature reduction has been
accomplished in cooling towers  (plants B  and  E)  and  in  spray  ponds
(plant  F),  or by simply recycling to a storage pond of sufficient area
so that surface evaporation maintains a stable temperature.
                                  50

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The suspended solids concentration in recycled  waters  used  in  cement
coolers  can  increase because the cooling stream in many cement coolers
is open to a dust-laden atmosphere.  If a cooling pond is used  to  cool
the  water before recycling, the pond can also serve as a settling pond.
However, if cooling towers are used, a small-volume  "bleed"  or  "blow-
down"  stream  from  the recycle stream is normally provided to maintain
suspended and precipitable dissolved solids at a low concentration.

At a few plants, waste cooling waters from bearings or  compressors  may
contain  lubricants.   Such  cooling waters can be segregated to prevent
dilution and treated to remove lubricants if necessary.   Flotation  and
skimming  usually  suffice  for  removal  of  lubricants,  but  emulsion
breaking may be needed in extreme cases.

Process Water

Process water as defined in this report refers only to the slurry  water
used in wet plants.  Since this water is evaporated, no direct discharge
is  associated with it.  However, precautions need to be taken to insure
that overflow from slurry tanks,  leaks  from  slurry  Ixnes,  and  tank
clean-up  is  prevented from entering the discharge from the plant or is
adequately treated before discharge.  As discussed above, at  many  wet-
process  plants the slurry mix itself can represent a convenient control
measure for handling at least some wastewater generated  in  the  plant.
Unless  these  wastewaters  are  highly  alkaline,  they  can be used to
prepare the slurry, as is done at plants  A,  B  and  C;  the  water  is
evaporated  in  the kiln, and the wastes that would otherwise have to be
treated or eliminated by other control  measures  are  consumed  in  the
product.

Runoff Water

For  plants collecting a high-alkali dust not returnable to the process,
surface dumping on the plant site or  in  an  adjacent  quarry  is  most
common.   Disposed  of in this way, the dust could affect the quality of
the plant effluent through  runoff  or  quarry  dewatering.   Therefore,
adequate  precautions  must  be  taken to enclose the dust disposal area
with dikes to contain runoff and to use areas of the quarry not  subject
to flooding by ground water.

Another  technique for disposal of dust is mixing its with water to make
a slurry that is pumped into a lagoon.  In some cases the overflow  from
the  lagoon  is  discharged.   However,  in the past few years, at least
three plants that  slurry  their  discarded  dust  have  eliminated  the
overflow  from  the lagoons by recycling this water for slurry disposal.
Plant H illustrates this practice.

Contaminants, primarily in the  form  of  suspended  solids,  can  enter
wastewaters in other ways; such as, in plant clean-up and truck washing,
                                   51

-------
and  by  pick-up  of dust by storm runoff waters.  The amounts of solids
introduced into wastewaters by plant cleanup can be  minimized  by  good
maintenance  and  operating procedures to minimize solid spillage and to
return dry dust to the process, and the  solids  introduced  into  otc-rn
runoff waters can be minimized by paving areas for vehicular traffic, by
providing  good  ground  cover  (e.g. grass) in other open areas, and by
removing accumulations of dust from roofs and buildings  for  return  to
the process.  Implementation of more stringent air pollution controls is
expected  to  result  in  a significant reduction in suspended solids in
runoff water.

If introduction of solids into wastewaters cannot be prevented, settling
ponds can be provided for the wastewaters that are affected by suspended
solids build-ups (e.g. the waters from floor-drainage sumps, waters from
raw-mill cleaning and slurry-pump leakage  in  wet-process  plants,  and
storm water runoff).

Treatment_TTechnQloqy

With the exception of settling ponds for the removal of
suspended solids, treatment of wastewater in the cement industry
is practiced primarily at leaching plants.

Leachate Water

As  mentioned in Section VI, pH, alkalinity, suspended solids, and total
dissolved solids (principally  potassium  and  sulfate)   are  pollutants
present  in the effluent from leaching plants.  The treatment technology
currently practiced can adequately control pH, alkalinity, and suspended
solids, but not dissolved solids.

Neutralization by the addition of mineral acids such  as  sulfuric  acid
has  the  following  effects:  it lowers the pH to any desired level; it
eliminates alkalinity by  neutralization  of  hydroxyl,  carbonate,  arvl
bicarbonate ions if it is followed by aeration to remove carbon dioxide;
oiicl  it  dissolves  acid-soluble particulate matter such as lime that is
prei.tnt as suspended solids in the leachate overflow.  However, it  adds
tc  the  total  dissolved  solids  content  because the sulfate ions are
h'.'.i-*ier than any of the anions that are removed by neutralization,

Carbonation lowers the pH by  replacing  hydroxyl  ions  with  catbonate
ions.   Additional  carbonation  converts  carbonate ions to bj Cdiboa-ate
ions.  Total alkalinity is  not  reduced  by  carbonation,,  because  the
c.":bon  dioxide  escapes  when  the bicarbonate solution is acidified or
aerated.  However, carbonation can Le used to reduce the hardness ot -;:hs
IfMChate,  The solubility of calcium reaches a minimum value of  ^6  ppm
(at  16°C1  when the pH has been lowered to 9,5 by carboriaticn, as r;nov,-r.
in Figure 10 (39) .  Any subsequent addition of carbon dioxide  t~  io^er

-------
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the  pH raises the solubility of calcium because calcium bicarbonate has
nearly the same solubility as calcium oxide.

The above discussion suggests that carbonation might be advantageous  as
a  treatment for leachate.  Overflow from the primary clarifier could be
carbonated with stack gas to lower the pH to 9.0, near the  pH  required
for  minimum  solubility and an acceptable pH for discharge.  This would
cause precipitation of calcium carbonate which could  be  removed  in  a
secondary clarifier or settling pond.

Carbonation  may  reduce  the  dissolved  solids by converting dissolved
calcium oxide to less soluble calcium carbonate which  appears  as  fine
suspended solids that must be removed by settling.  Suspended solids may
be  controlled  to  less  than  50  mg/1 as is done in Plant I by proper
design and operation of the clarifiers.

The degree of clarification is determined by several  factors  including
the length of time the leachate remains in the clarifier, the turbulence
in  the  clarifier,  and the characteristics of the dust.  The residence
time and the degree of turbulence in  the  clarifier  are  fixed  design
parameters.   However, the characteristics of the dust can be controlled
to some extent.

One way of controlling the dust characteristics  is  by  selecting  what
dust  is  to  be  leached.  Maximum flexibility of selection is achieved
when electrostatic precipitators are used to collect the dust  from  the
kiln exhaust gases.  In electrostatic precipitators the larger particles
are  more  easily  removed from the gas stream, so they are recovered in
the first stages  of  the  precipitator.   The  smallest  particles  are
collected  in  the last stage.  Precipitators are designed so that these
fractions of dust are segregated in several hoppers.  The fine particles
in the last hopper have significantly higher  alkali  content  than  the
coarse  particles  in  the first hopper.  By leaching only the dust from
the last hopper, the load of the leaching system  can  be  significantly
reduced.   However, in Plant I all the collected dust is leached because
the coarse particles make the slurry easier to handle.

The settling characteristics of the dust can also be controlled  by  the
addition of flocculating agents to the water used for leaching the dust.

Although  none  of the leaching plants use a treatment process to remove
dissolved solids from the  leachate  effluent,  there  are  methods  and
technologies  that  are  potentially applicable.  Several processes that
might be employed  include  evaporation,  precipitation,  ion  exchange,
reverse  osmosis,  electrodialysis,  and  combinations  of  these.  Each
process must be considered in relation to the problem of disposal of the
removed salts.  Some  of  these  processes  have  technical  limitations
associated  with  their  use  in  this application.  For example, in ion
exchange large amounts of acid and base are required to  regenerate  the

-------
resins.   The  amount  of waste material would be approximately twice as
great as for other separation processes.   Similarly,  although  reverse
osmosis  is  useful  for desalination of dilute solutions, the dissolved
solids content of the leachate is  too  high  for  this  process  to  be
practical.


Evaporation  of  the  leachate could potentially eliminate the effluent.
Although solar evaporation would have low operating cost,  it  could  be
used only in arid climates and where a large amount of land is available
for  evaporation  ponds.   Evaporation  by  submerged combustion or heat
exchangers involves considerable cost for  fuel  and  equipment.   Waste
heat  from  the  kiln  might  be  employed  for evaporation of leachate,
however, the economic feasibility of this practice is uncertain  in  the
absence  of  industry experience.  Reduction of the quantity of water to
be evaporated by concentrating the leachate in some other process may be
desirable.

A technology that appears promising for  concentration  of  leachate  is
electrodialysis  (ED),  which  has  been  successfully  applied  to  the
concentration of sea water for the recovery of salt.  (30)   If  ED  were
used,  the  concentrated  stream would be more easily evaporated and the
concentration of salts in the dilute stream would be low enough to allow
it to be recycled to the  leaching  system.   ED  could  be  transferred
directly to the concentration of leachate with two variations.

First, calcium ions must be removed to prevent precipitation and fouling
of membranes.  Reducing the pH to 9.5 by carbonation with stack gas will
reduce  the  concentration of calcium ions to a minimum as was discussed
above.

second, reduction of the concentration of salts to  a  point  where  the
water  could  be  recycled  in  the leaching process will raise the cell
resistance.  Thus,  more power  must  be  provided  than  is  needed  for
recovery  of  salt  from  sea  water.   A  third  desirable  feature  is
additional carbonation to reduce the pH of the clarified  leachate  from
9.5 to about 8.0.

A  flow diagram of a conceptual design for electrodialytic concentration
of leachate is shown in Figure 11.  At a typical leaching  plant,  about
6.5 kg/kkg (13 Ib/ton) of dissolved solids are generated in the leachate
stream,  of which potassium salts are a major component.  If the typical
daily production of clinker is 1600 metric tons (1750 tons),  the  plant
will  generate  about 10 metric tons (11 tons) of salts per day or about
3300 metric tons (3650 tons)  per year.  The costs of  operating  such  a
facility would amount to about $350/day.

A  detailed description of electrodialytic concentration of electrolytes
is given by Nishiwaki  in  Chapter  6  in  Reference  30.   conventional
                                   55

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                                           56

-------
  Partially
  desalted  <•
  solution
.            .
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                              H2O
                                   V//////J
                                                              Concentrated
                                                                 brine

t.
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      membranes               Solution to be
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      Figure 11A.  Diagram of  Electrodialytic Concentration Stack
                              57

-------
electrodialytic  equipment  may be used.  The only major change from the
practices  used  in  electrodialysis  for  desalination  is   that   the
concentrating  compartments  are  not  fed  any  water;  the  water that
overflows the concentrating compartments and is withdrawn  as  brine  is
transferred through the membranes by electro-osmosis and osmosis.

A  diagram of an electrodialytic stack for concentrating electrolytes is
shown in Figure 11A.  The stack consists of many (up  to  2000)   cation-
and  anion-exchange  membranes  arranged  alternately  to  form solution
compartments, as  indicated,  between  a  cathode  and  an  anode.   The
solution   to   be   concentrated   is   circulated   through  alternate
compartments, as shown.  The other set cf compartments are closed at the
bottoms.  No solution is fed to them but they are filled with  solution.
When  electrical  current  flows  through  the stack, cations and anions
transfer  from  the  circulating  solution  through   the   ion-exchange
membranes into the closed compartments.  Simultaneously, water transfers
from  the  circulating  solution  through  the  membranes as a result of
electro-osmosis and osmosis.  The water, so transferred, overflows  from
the  tops of the closed compartments along with the transferred ions and
is withdrawn as concentrated brine.  It  should  be  re-emphasized  that
although  only  a  few  membranes and solution compartments are shown in
Figure 11A, commercial stacks may have as many  as  2000  membranes  and
1000 solution compartments.

The  usual mode of operation for electrodialytic concentration stacks is
known as feed-and-bleed operation.  In this mode  of  operation  only  a
small  portion of the circulating solution is "bled" from a recycle line
and returned to the cement process for reuse in  slurrying  dust.   Most
(perhaps  80%)  of the solution is mixed with a volume of fresh leachate
equal to the amount "bled" from the system and recycled  to  the  "feed"
side of the electrodialysis stacks.  With this "feed-and-bleed" mode of
                                  58

-------
operation  it  is  possible  to transfer ions through the membranes at a
high  rate,  without  decreasing  the  concentration  of  ions  in   the
circulating  solution  appreciably in any one passage through the stack.
It is  desirable  to  maintain  a  relatively  concentrated  circulating
solution  because with very dilute solutions the resistance of the stack
would be high.  Therefore, the  energy  requirements,  which  depend  on
resistance, would be high.

In  the conceptual design, shown in Figure 11, leachate from the primary
clarifier would be carbonated with stack gas in two turbo-agitated tanks
arranged in  series  to  reduce  the  pH  to  9.5  so  that  CaCO3  will
precipitate.   The  liquid  will  be  pumped to a secondary clarifier in
which CaCO3 can deposit on existing CaCOS particles carried  within  the
clarifier  as  inventory.   The  underflow  from this clarifier would be
pumped back to the primary classifier; the overflow would be transferred
to two secondary carbonators of the same type as the primary ones.

In the secondary carbonators the pH is reduced to  8.0  to  convert  the
CaCO3  remaining  in  solution  to  Ca(HCO3)2.  This step is expected to
prevent precipitation of calcium ions as the  carbonate,  since  calcium
bicarbonate  is  more  soluble  than  calcium  carbonate.   As  an added
precaution against precipitation of calcium as either the bicarbonate or
the sulfate, univalent selective  cation-exchange  membranes  should  be
used.    (Such uni-valent selective membranes are described and discussed
by Nishiwaki in Reference 30.)

No preatreatment of  the  feed  other  than  that  described  above  and
filtration  is  expected  to  be needed.  Iron and manganese, which have
caused troubles with ED units for desalination, should not be present in
this feed because any iron or manganese present in the  dust  should  be
fully oxidized, and should not leach from the dust at the high values of
pH  in  the leaching section.  If silica leaches from the dust, it could
present a problem with silica slimes building up on the membranes.   The
extent to which silica might be leached is not clearly evident.

The solution from the secondary carbonators would be pumped through sand
filters  and into the ED stacks.  As discussed previously, the ED stacks
would be operated by a feed-and-bleed method.   The  partially  desalted
solution  bled  from  the  feed-andbleed system would be returned to the
primary clarifier for reuse in slurrying dust.  The  concentrated  brine
that  overflows from the closed compartments of the stacks would be sent
to an evaporation step.  The evaporation could be performed in  a  solar
pond  in  arid  climates, or by other means in non-arid climates.  Since
only about 10,000 gal/day of concentrate must be  evaporated,  the  cost
should be low.

Cost for a typical operation, based on this conceptual design, have been
estimated and are presented in Section VIII.
                                   59

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The most valuable and most abundant cation in the leachate is potassium,
which   if   suitably  recovered  might  be  profitably  marketed.   The
agricultural grade of potassium sulfate has a market price  of  $77  per
metric  ton  of potassium oxide (38).  Recovery of potassium from cement
dust was practiced during World War I to free the  U.S.  of  a  monopoly
exercised by the German Industry.   One cement plant reportedly recovered
17.5  kg  of potassium sulfate for each metric ton (35 Ib/ton) of cement
produced  (15) .

In 1959 Patzias (21)   made  a  study  of  a  method  for  extraction  of
potassium sulfate from cement dust.  By leaching at high temperatures in
a pressurized vessel he achieved 84% recovery of alkalies from the dust.
After   filtration   the   leachate  was  concentrated  by  evaporation,
neutralized with sulfuric acid, and evaporated to dryness.  For a  plant
treating  180  metric  tons/day  of  dust  containing 1.66% of potassium
sulfate the calculated capitalized  payout  for  the  process  was  0.44
years,  and  the  calculated net profit was $101,304.  There would be no
discharge from this process because all of the water from  the  leachate
is   evaporated.    While  a  process  based  on  this  concept  appears
technically sound, it apparently has not been exploited by the industry.
The economic feasibility re-evaluated in view of present costs indicates
a recovery cost of about twice the present market price.  A  flow  sheet
illustrating this concept is shown in Figure 12.

Description of Plants _that^Dgnionstrate
Control and Treatment Technologies

About  30  identified  plants  in   the  industry  are  able  to  achieve
essentially no discharge of pollutants by application of the control and
treatment technologies discussed  above.   Eight  of  these  plants  are
discussed  below  to illustrate variations in particular methods used to
minimize discharge of pollutants.   While no plants in the leaching  sub-
category  have  achieved  this  level  of  performance,  an example of a
leaching plant  and  a  plant  with  a  wet  scrubber  are  included  to
illustrate  features of existing control and treatment technology which,
if implemented in proper combination, would result in minimum  discharge
of  pollutants.   The  information was obtained through on-site studies,
questionnaires, and telephone interviews.

Plant A - Complete reuse of all water, including runoff

This wet-process plant built in 1939 has electrostatic precipitators  on
four  kilns  and bag houses on two kilns.  All dust collected  (about 10*
of the kiln feed) is returned to the kilns without treatment   since  the
raw  materials  used  are  low  in  alkali  content.   The overall water
management plan for Plant A is shown in the simplified diagram in Figure
13.
                                 60

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        Quarry
       Elevated ]
         Pond   I
                  Slurry Dredged from Pond

                       (intermittent)
            00 1/kkg
           Raw Materials
                       Raw Material
                       Beneficiation
                         Primary
                         Raw Mill
                                     40,000 1/kkg
                                     Raw Materials
                        Secondary
                         Raw Mill
                                      3850 1/kkg Product
                           Evaporation
                                1
                           Kilns
                 Runoff
               Truck Washej
                House-
                 keeping
    Make-up Water
        from    	•
    Municipal System
     37 1/kkg Product
                               Bearing
                               Cooling
Cement
Cooler
                               Cooling
                                Tower
Settling
  Pond
 (sump)
   i  Slowdown
            Figure 13.   Diagram of Water-Management
                       Plan for Plant A

-------
The bearing-cooling water systems  in  this  plant  are  closed  recycle
systems.   A small amount (less than 1%) of the recycling stream is bled
off and sent to the sump.  An equal amount of  fresh  make-up  water  is
added.  In the cement cooler the finished product is conveyed vertically
through a large cylinder by a screw mechanism.  Heat is removed by water
flowing  through  a  jacket  on  the outside of the large cylinder.  The
temperature of the heated water is reduced in a  cooling  tower.   Fresh
water  is  added  to  the  recycling stream to replenish the evaporative
losses in the cooling tower.  The tower blow-down  (less than 1%  of  the
the recycle stream) goes to the sump.

The  water needed for cooling-water make-up, raw-material beneficiation,
and slurry preparation comes from an elevated pond as  shown  in  Figure
13.   The  pond  is  fed  by  water  pumped from the quarry and by water
purchased from a municipal water system.  Water flows from the  pond  to
the  raw-materials  beneficiation  plant.   Water accompanies the slurry
that is dredged from the pond and sent to  a  thickener.   The  overflow
from  the  thickener  is  pumped  back to the pond, and the underflow is
pumped to one of two raw mills.  Solids from the first raw mill are  fed
to  the  second  raw  mill  (along with some water).  The slurry from the
second raw mill is kiln feed.

All waters from plant clean-up and truck  washing  drain  into  a  sump.
Storm  runoff  waters  are intercepted by a series of ditches and led to
the sump.  The sump also  receives  blow-down  water  from  the  cooling
systems  and  drainage  from a sand pile  (the company sells construction
sand from raw-materials beneficiation).  The sump  is  provided  with  a
level  controller.   Water  is  pumped  back  to  the elevated pond on a
intermittent basis, controlled by a level  controller.   The  pumps  and
level  controller  are  provided  with  alarm  systems  to  notify plant
personnel in case of pump failure, because the sump could overflow  into
an adjacent stream if the pumps failed during heavy rainfall.

Plant B - Complete recycle and reuse of water

This  plant  uses  oyster  shells as raw material.  Wastewater treatment
facilities installed in 1973 consist of a system of  settling  ponds  to
clarify  wastewater from a clay-washing operation and to recover settled
solids for use in the process.  Electrostatic precipitators are used  to
collect  kiln dust (about 6% of the kiln feed is collected as dust).  No
dust is returned to the kilns.  Some of the dust is used  along  with  a
stabilized  shell  mixture  for  fill dirt on road projects in the area.
The rest of the dust is returned to an unused area of the clay pits.

In Plant B water is obtained from a deep well  and  is  first  used  for
cooling,  as  shown  in  Figure  1U.  The water for the cement cooler is
recycled through a cooling tower and water is added  from  the  well  to
replenish losses.
                                  63

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               (1150 1/kkg)
                               Bearing Cooling
          Make-up Water
           (80 1/kkg)
                           Cement Cooler
                       Evaporation (80 1/kkg)
                           Cooling Tower
  Slurry
Preparation
                    (80 1/kkg)
                    (1030 1/kkg)
 Belt Spray
(for shell)
Raw Materials
Beneficiation
                                   Evaporation  (1110 1/kkg)
                                  	L
                                      Kilns
                                    Evaporation  (40 1/kkg)
                                      Clinker
                                      Cooler
             Figure  14.  Diagram of Water-Management
                         Plan for Plant B
                             64

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Some  of  the  wastewater  from  the bearing-cooling circuits is used to
spray the belt used to transfer oyster shells from the unloading station
at the dock to the raw mills to prevent the shells from sticking to  the
belt.   This  water  is subsequently used for slurry preparation.  Other
wastewater from the bearing cooling  system  is  used  for  raw-material
beneficiation and subsequently used for slurry preparation.  Still other
bearing  cooling  water is used to cool cement clinker by direct contact
and is evaporated.  No wastewater is discharged from this plant.

Plant C - Complete reuse of water

This wet-process plant, built in the twenties is situated adjacent to  a
creek.   Two  smaller  creeks  on  the plant site are fed principally by
runoff, and originally drained into a larger creek.  The flow from these
two creeks has been diverted to a sump to provide a source of water  for
the  plant.   The  larger  creek  is  connected  to  the  sump through a
spillway, as shown in Figure 15.

All process water for cooling, plant clean-up, slurry  preparation,  and
other  uses  is  pumped  from  the  sump to an elevated tank.  In normal
operation the plant uses more  water  for  slurry  preparation  than  is
normally  available from the two small creeks.  Since the water used for
slurry preparation is evaporated in the kilns there is a net  inflow  of
water  from  the larger creek through the spillway into the sump.  Thus,
no water is discharged from this plant, except during periods  of  heavy
rainfall, when the level of the water in the sump is higher than that of
the larger creek.

All  cooling water is discharged through two outfalls into the two small
creeks.  All waters used in plant clean-up and truck washing  and  water
that has seeped into the quarry, which is on the plant property, is also
discharged into one of the creeks.

All  of the dust is collected by cyclones at this plant (about 6% of the
kiln feed is collected as dust)  and is disposed  of  by  surface  piling
within  the  plant area.  Any runoff of water from the dust piles drains
into the sump.

Plant D - Once-through cooling water isolated from contamination

As indicated in Figure 16, there are  two  sources  of  water  for  this
plant:   a  river,  and a shallow well.  River water is pumped through a
loop of pipe that traverses the area in which the mills  and  kilns  are
located.  About 1090 1/kkg (270 gal/ton) is withdrawn from the pipe loop
and used in the process.  About 23,000 1/kkg  (5500 gal/ton) is withdrawn
for  use  as  cooling  water for bearings and compressors.  This cooling
water re-enters the pipe loop and is discharged to the river along  with
some  excess  water in the loop that is not used, except for cooling the
wastewater from bearing  cooling  by  dilution.   About  230  1/kkg  (55
                                  65

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   I
Creek 1
   i
                    Creek  3
                            500
                           1/kkg
        Bearing
        Cooling
                     Sump
                    Holding
                     Tank
       Dust Pile
        Runoff
 160
1/kkg
Cement
Cooler
                            10
                           1/kkg
         House-
        Keeping
                                    Slurry
                                Evaporation 800 1/kkg
                                    Kiln
                                   Quarry
                     Creek 2
         Figure  15.  Water-Management Plan for Plant C,
                                66

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         Intake
                                                   DRAFT
                     Raw
                    Mills
                      I
                            Cooling Water(208 1/kkg)
        Process Water
  I
River
 Evaporation  (1090 1/kkg)
  f
                    Kilns
                               Cooling Water
  I
 Evaporation (230 1/kkg)
                  Clinker
                  Cooler
        _i
          Discharge
                   Finish
                    Mill
      (375 1/kkg)
                       Well
           Figure 16-
Diagram of Water-Management
Plan for Plant D
                            -.1

-------
gal/ton)  is  also  withdrawn  from the pipe loop to cool clinker.  This
water evaporates.  About 375 1/kkg (90 gal/ton) of water is pumped  from
a  shallow  well  to  the  cement  cooler.  The warm wastewater from the
cooling operation is discharged to the river.           '»>-,.,«, -'    «

Plant E - Recycling of all cooling water with cooling tower

This is a dry-process plant, built in the 1950's.   The  dust  from- the
kilns  is  collected in bag houses.  Almost all dust collected  (about 5%
of the kiln feed is collected as dust)  is returned to the kilns.  Only a
small amount (0.015 metric tons per metric ton of product)  is wasted  by
returning it to the quarry.

With  the  exception  of  small  amounts of water used for cleaning (e.g.
plant and truck clean-up)  all water used  is  for  non-contact  cooling.
The  wastewater  from all cooling operations, typically 625 to 730 1/kkg
(150 to 175 gal/ton) of product, is recycled through two cooling towers.
The blow down from the towers (about 12 1/kkg of product)  is discharged.
This amount of water could easily be evaporated at low cost.  The  water
required  to  replenish  the  blow-down  and  evaporative  losses in the
cooling towers amounts to about 83 1/kkg (20 gal/ton)  of product,  which
is obtained from a deep well.

Plant F - Recycling of all cooling water with spray pond

This  is a dry-process plant built before 1900.  The latest modification
that affected water management practices was the installation in 1965 of
a reservoir with spray cooling and a recycling system for cooling water.
About 0.1 metric tons of dust per metric ton of product is collected  in
a multicyclone collection system and is returned to the kiln.

Water  requirements  for bearing cooling and the cement cooler are about
2300 1/kkg (550 gal/ton) of product.  All cooling water is  recycled  to
the  spray-cooled  reservoir.   In  the  reservoir  about  230 1/kkg (55
gal/ton) of product is evaporated.  This plant also uses water  to  cool
cement  clinker  in  a direct-contact process.  This water, 83 1/kkg (20
gal/ton) of product, is evaporated.  Water is supplied to the  reservoir
at  a  rate  of about 300 1/kkg (72 gal/ton) of product to replenish the
evaporative losses.

Plant G - Once through cooling water with settling pond

This is a dry-process plant about 35 years  old.   The  plant  withdraws
about  3000 1/kkg  (730 gal/ton)  of water from a river as shown in Figure
17.  This water is treated by flocculation and settling  and  about  170
1/kkg   (40  gal/ton)  of  backwash  water from the water-treatment plant
drains to a settling pond.  Approximately 2870 1/kkg   (690  gal/ton)  of
the  treated  water  is used as cooling water.  A portion of the cooling
water, about 375 1/kkg  (92 gal/ton) of product is evaporated in  cooling
kiln gases and cement clinker.
                                  68

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    (375
     1/kkg)
(2495  1/kkg)
                        Intake-Water
                         Treatment
                   Evaporation
                   Kiln Gas
                    Cooling
                   Evaporation
                    Clinker
                    Cooling
                    Bearing
                    Cooling
                    Cement
                    Cooler
                      (3040
                     .1/kkg)
                                  Backwash
                                  (170  1/kkg)
                             Settling
                               Pond
                                   I
                                River
                                                     I
     Figure  17.
Diagram of Water-Management
Plan for Plant G
                        69

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  Dust from
Precipitator
      l
Precipitator
   Hopper
           Agitated
             Tank
Stack
 gas
                             Carbonator
     Make-up Water
     (1190 1/kkg Dust)
        Inactive Lagoon
        (being excavated)
  Active Lagoon
        Figure 18.  Diagram of Dust-Handling
                 System at Plant H

-------
All other water drains into a settling pond.  Water overflows a spillway
at  the  low end of the settling pond into a small creek that leads back
to the river.

Plant  H  -  Recycling  of  waste-dust-slurry  water  with   stack   gas
neutralization

This  is  a wet-process plant about 10 years old.  Dust from the kiln is
collected in an electrostatic precipitator.

In 1964 a dust-leaching system was installed in the hope that  the  dust
could be returned to the kiln.  However, the system could not be made to
work acceptably.  some of the components of the system were then used to
develop  a  system  for disposal of the dust.  This system appears to be
adaptable for use at other plants and is, therefore, described below.

As shown in Figure 18, dust from the precipitator hopper is  transferred
to  an  agitated tank, where it is mixed with water.  A slurry is pumped
from this tank through four gas absorbers in series.  A small amount  of
the  gas  from  the  stack  is  sparged  through  the  slurry in the gas
absorbers to reduce the pH from about 12 to about  8  by  absorption  of
carbon  dioxide.   The  slurry is pumped from the last gas absorber to a
system of two lagoons.  The distance to the lagoons is about 460  meters
(1500  feet),  and  much of the distance is traversed by fire hose.  The
fire hose is used because precipitates tend to deposit inside the  hose,
and  periodically  the  hose  is  collapsed by walking or beating on the
outside of it to break-up and flush out the deposits.


Both the dust and precipitates  formed  by  carbonation  with  kiln  gas
settle  in  one  of  the  lagoons.   The water drains into a sump in the
lagoon that is provided with a floating suction-head
and a pump.  The clear water is pumped back to the  dust-treatment  tank
for  reuse  in slurrying more dust,  some water is lost from the lagoon.
Since the lagoon was made with an impermeable  clay  bottom,  presumably
most of the water is lost by evaporation.  The make-up water supplied to
replenish  losses  averages  about  1300 1/kkg  (315 gal/ton) of dust, or
about 83 1/kkg  (20 gal/ton)

Each of the two lagoons is about 2.43 ha  (6 acres) in area.  Two lagoons
are provided so that one could be used  to  receive  slurry,  while  the
other  was  excavated  for sub-base fill for use in road and parking lot
construction.  The plant sells  the  sub-base  fill  to  a  construction
company.   By  the time one lagoon is filled with solids, the second has
been excavated so it can be used to receive slurry.

Plant I - Sedimentation for removal of suspended  solids  from  leachate
stream
                                  71

-------
This  plant  uses  cyclones  followed  by electrostatic precipitators to
collect kiln dust.  If all of the collected dust were returned  directly
to  the  kilns,  the alkali content of the product would be 0.8 to 0.9%,
well above the 0.6% maximum for  low-alkali  cement.   By  leaching  the
alkalies  from  the  dust  before it is returned to the kiln, the alkali
content of the product can be maintained in the 0.5 to 0.7X  range.   It
is  the  practice  at  this plant to leach all of the collected dust and
return it to the kiln.

The plant has two kilns and two separate dust  collection  and  leaching
systems.   Dust collected in the cyclones and precipitators of each kiln
is conveyed to a pug mill where well water is mixed  with  the  dust  to
make  a  slurry  containing  10%  solids.  The soluble alkalies, usually
about one third to one half the alkali content, dissolve  quickly.   The
slurry  enters  the  center  of  the  clarifier  and is distributed by a
revolving bar.  The leached dust particles settle to the bottom  of  the
clarifier  to form a dense slurry.  The rate of removal of material from
the bottom of the clarifier is controlled to maintain a  solids  content
of  about  45%  in  the  underflow.  The underflow is pumped back to the
kiln.

The combined overflow from the two  clarifiers  flows  directly  to  the
river.   It  has  a  pH  of  12.9 and is only slightly turbid (suspended
solids content of 40 mg/1). This low value of suspended  solids  content
suggests that the 13.7 m  (45 ft)  diameter of these clarifiers provides a
rise-rate that is adequate. (A similar plant with 8.5 m (28 ft)  diameter
clarifiers had 660 mg/1 suspended solids in the overlow.)

Plant J - Treatment of wet-scrubber effluent

This  plant  uses  a  wet  scrubber  as  its main dust collector for the
combined exhaust from three kilns. The effluent  from  the  scrubber  is
treated  with  a  polyelectrolyte before it flows into a clarifier where
the major portion of particulate matter is removed and returned  to  the
raw  mills.  The  retention time in the clarifier is 3.7 hours.  Sulfite
and sulfate that  are  adsorbed  from  -the  stack  gases  by  water  are
apparently  converted  to  hydrogen sulfide in the clarifier  (perhaps by
sulfur bacteria), since there is a strong odor of  hydrogen  sulfide  at
the  clarifier  if  chlorination is not practiced.  Chlorine is added to
the leaving the clarifier to oxidize the sulfide ions.  Then  the  water
cascades  down  the  side  of  the  quarry into a large pond.  After the
particulate matter settles the water is recycled from the quarry through
the scrubber.

The decision to install the wet scrubber described above  was  based  on
the  significantly  lower  cost  of  a  scrubber compared with that of a
haghouse or an  electrostatic  precipitator.  This  cost  advantage  was
reduced  somewhat  by  subsequent  modifications to meet wa-cer pollution
control standards.  Although  plagued  with  many  operational  problems
initially, the scrubber is now operating satisfactorily.
                                   72

-------
                        SECTION VIII

        COST, ENERGY, AND NO&-WATES QUALITY ASPECTS


Cost and_ Reduction Benefits^ of ^Alternative Control and
Treatment Technologies

A  detailed  analysis  of  the costs and pollution reduction benefits of
alternative  control  and  treatment  technologies  applicable  to  both
subcategories  of  this industry is given in this section of the report.
Table 12 summarizes the results of the analysis.

Nonleaching Plants

The present waste loadings from a typical nonleaching plant are shown in
Table 12.  These values represent the median of all values greater  than
0.005 kg/kkg (0.01 Ib/ton) of product reported by nonleaching plants.
Alternative  A - Recycling and reuse of all water used in manufacturing,
and containment or treatment of runoff from kiln-dust piles

This alternative will result in essentially no discharge of  pollutants.
The  investment  cost of implementing this technology at a typical plant
will be about $200,000 including a cooling tower  ($94,000) or spray pond
($91,000), the necessary piping ($76,000),  and  containment  dikes  for
coal  piles  and   kiln-dust piles ($35,000).  If an evaporative cooling
pond is used, it would cost about $160,000  including  piping,  but  not
including land cost.

The  operating  costs  of Alternative A will range from about $20,000 to
$30,000 per year  including  maintainence,  sludge  removal,  chemicals,
labor,  cost of power, and taxes and insurance.  Power costs are limited
to pumping and amount to $13,000 per year.

Alternative B - Limited reuse and in-plant controls

This alternative consists of isolation of cooling streams from  possible
contamination,   reuse  of  cooling  water  in  feed  slurry (wet-process
plants), retention and reuse or treatment  of  miscellaneous  wastewater
(§•9i   truck  washing)  and containment or treatment of runoff from coal
piles and kiln-dust piles and would also result in essentially
                                 73

-------


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                                            76

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no discharge of pollutants in manufacturing effluents.

 Cost of implementing this alternative at  individual  plants  may  vary
widely  but on the average will be comparable to that for Alternative A.
About 35 of 154 plants in the  nonleaching  subcategory  (23%)   are  now
achieving essentially no discharge of pollutants under either one of the
alternatives described above.

Leaching Plants

The  present  waste  loading  from  a typical leaching plant is shown in
Table 12.  These typical loadings are substantially  higher  than  those
from the typical nonleaching plant and reflect the added presence of the
leachate stream.

Alternative C - Segregation and Treatment of Leachate Stream

The  nonleaching  streams  of  leaching plants are treated like those of
nonleaching plants under this alternative.  Treatment  of  the  leachate
stream consists of neutralization of the leachate with stack gases to pH
9.0  followed  by  secondary  sedimentation  to remove both the residual
suspended solids that were present in the  leachate  and  the  suspended
solids   (calcium  carbonate)   created  by the neutralization with carbon
dioxide.

This alternative will result in an acceptable pH of less than 9.0, and a
suspended solids level of not more than 0.15  kg/kkg   (0.30  Ib/ton)   of
dust  leached.   Dissolved  solids  will  remain  at about their present
level.

The cost of implementing Alternative C will be about $425,000  including
$165,000  for  the  control  of  nonleaching  streams  and  the  cost of
installing a stack-gas neutralization system and a clarifier ($260,000).
Operating costs of Alternative  C  will  range  from  about  $35,000  to
$45,000 per year.

One  of  the 12 plants in the leaching subcategory is presently equipped
to implement  this  alternative  with  minor  adjustments  in  operative
procedures, this plant could meet the limitations of this alternative.


Alternative D - Recycling of Leachate Water

This  alternative  consists  of  reducing  the  dissolved  solids in the
leachate stream by means of electrodialysis and recycling the  partially
demineralized  leachate.   The  technology  of  alternative  C  must  be
implemented to provide a stream  acceptable  for  electrodialysis.   The
concentrated  brine  resulting form this treatment may be evaporated for
the recovery of potassium salts or contained in a suitable pond.
                                 77

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Implementation of Alternative D will result in essentially no  discharge
of pollutants.  None of the plants in the leaching subcategory, however,
is employing the technology described as Alternative D.


Alternative E - Abandonment of Existing Leaching Operations'

Under  this  alternative,  plants  that  presently leach kiln dust would
abandon the practice and adopt either alternative  A  or  B  which  will
result  in no discharge of pollutants.  A contractor would haul the dust
for about $0.50 per ton.  The value of the wasted dust  would  be  about
$2.00  per  ton. (46)  Therefore, the annual cost of wasting 200 tons per
day of dust that is presently leached would be $165,000.

Effects_gf^Costs on the

The investment cost of $200.000 involved  in  implementing  control  and
treatment  technology at an existing nonleaching plant represents 0.5 to
1% of the estimated replacement cost of the plant ($20 to $40  million).
In terms of plant size, these costs represent about $0.35 per metric ton
of  capacity.  For plants in the leaching category, these figures may be
approximately doubled.

The increased cost of manufacturing cement will range from  about  $0.10
per metric ton at nonleaching plants to about $0.21 at leaching plants.

One industry consultant has provided the typical production cost figures
for  14  plants  presented  in Table 13 (5).  The production cost ranges
from $15.11 to $21.20 with an average of $17.52  per  metric  ton.   The
added cost of water pollution control will thus increase production cost
by  less  than  1.5%  at plants operating at full capacity.  Since these
costs are largely fixed costs and, thus, must be borne at any  level  of
production,  production  at less than full capacity will reflect higher.
added costs.
Energy Requirements

Because of the large energy requirement at a cement  plant,  about  1.25
million  kg  cal  (5 million BTU) in fuel and about 120 kwhr of electric
power per metric ton, the added power needed to  operate  the  recycling
systems is neglible (less than 0.1%).

Non-Water Quality Aspects

Non-water  quality  environmental effects of the alternative control and
treatment technologies described appear minor.

Some additional solid wastes will  be  generated  by  increased  use  of
sedimentation,  but the amount will be small compared to the quantity of
                                  79

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kiln dust normally wasted.  Moreover, the relatively  inert  wastes  are
acceptable for land fill.

The  increased cost of dust leaching may discourage its practice at r ome
plants and thereby add to the solid waste load and create localized dust
problems on windy days.

                       Plant
The  typical  plant  used  as  the  model  for  this  discussion  is   a
hypothetical  wet-process leaching plant with a rated annual capacity of
520,000 kkg (580,000 tons).  It operates continuously for 330  days  per
year  and produces 1,580 kkg {1,750 tons) of clinker per day.  The water
flow for  all  cooling  except  finished  cement  is  2,360  1/min  (600
gal/min) ; flow in the cement cooler is 1,130 1/min (300 gal/min) ,

About  130 kkg (150 tons) of dust are collected each day and leached for
return to the kiln; flow of  the  leachate  stream  is  510  1/min  (140
gal/min) .

The plant site is about 240 m x 400 m (800 x 1,200 ft)  not including the
quarry.  Layout of the plant is shown in Figure 1.

This typical plant varies from actual plants in the industry as shown in
Table  3.   The  typical  plant  represents  an average of actual  plants
studied.   Variation in the costs involved in  implementing  control  and
treatment technology at actual plants is difficult to predict.  A number
of  factors  are  involved and the actual costs will depend, on the plant
situation.  The usual considerations such as age and  capacity  will  be
less  important than such things as plant layout and the volume of water
used.

Cost Estimates

In this section are presented the assumptions used  in  calculating  the
cost of implementing control and treatment technology.

Inflation Index

All  final  costs  given  in Table 12 are reported in 1971 dollars.  The
basis for adjusting cost data is the Marshall & Swift  Annual  Index  of
Comparative  Equipment  Cost.  (2)  Table  14 presents a listing of this
index for the years 1959-1971.
Cooling Water Assumptions

The data base used in estimating cooling water usage was obtained for 40
plants from returned questionnaires.
                                  80

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"Bearing  cooling"  includes  all  machinery  cooling  in  the   plants,
including  compressors,  burner  pipes,  kiln  bearings,  grinders, etc.
Twenty-five plants report an average of  1,840 1/kkg  (490 gal/ton).   The
average daily production at these plants is 1,570 kkg  (1,750 tons).  The
flow is therefore 2,245 1/min  (600 gal/min) .

The  temperature  rise  was  measured  to  be  28°C  (5°F) at a number of
plants.

Cement cooler water reported for 21 plants was 945 1/kkg  (224  gal/ton)
or  1,000  1/min  (272 gal/min).  This figure was verified by considering
the cement.  The following data were used:

    Change in T = 79°C  (140°F)[From 140°C  (250°F) to 62°C (110°F]

    Change in T = 121°C - 43°C = 78°C  (250°F - 110°F = 140°F)

    Cp (clinker) =0.19 cal/°Cg

Heat removed from 1 kkg of cement is:

    0.19 cal/°Cg x 1000 gKgcal/kkg cal x 78°C =  14,800 kgcal/kkg
(53,200 BTU/ton)

For the typical plant this is:

    (1580 kkg/day x 14,800 kgcal/kkg)/1440 min/day = 16,200 kg cal/min.
(64,000 BTU/min)

If the temperature rise in the water is  14°C  (25°F) and  no  evaporation
takes place, the flow required is calculated as

16,200 kgca1/min/(14°c x 1 kgcal/°Ckg x  1 kg/1)  =  1160 1/min.
(310 gal/min) .

which  is  close  to  the  actual  average  of   1060 1/min  (280 gal/min)
reported.  For present purposes, the flow for cement cooling  was  taken
as 1130 1/min  (300 gal/min).

If both cooling streams are combined we  have:

    (bearing cooling) 2270 1/min o> 2.8°C  (600 gal/min o>5°F)
    (cement cooling)  1135 1/min a) 14°C  (300 gal/min 325°F)
    Combined 3405 1/min a 6.5°C (900 gal/min ffi 11.7°F)

To  provide for extremely warm weather we will assume a temperature rise
of 8.4°C (15°F) .

Cooling Tower
                                   81

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Guthrie (5)  gives the base cost of a  cooling  tower  for  8.4°C   (15°F)
temperature  rise  and  3785 1/min (1000 gal/min) flow as $45,000.  This
includes:   cooling  tower,  concrete  basin,  pumps  and  drives,  field
erection,   and  indirect  costs.   The  bare-module  cost will be  1.75  x
$45,000 or $78,750.  Contingencies and contractor fees of 20X are  added
for a total of $94,000, total installed cost (1968-$).

Cooling Pond Costs

Cost  information provided by a single company on a spray pond to  handle
their cooling water (the production rate is 1090 kkg/day ('1200  ton/day)
and  flow is typical)  is $100,000 total installed cost in 1965.  For the
typical plant production of  1590  kkg/day   (1750  ton/day)   and   a  0.6
exponential  scaling  factor,  the  cost  for the typical plant would be
$125,000  (1965$) .

The size of an evaporative cooling pond required for this application is
determined by climatic conditions.   For  midsummer  conditions  of  50%
relative  humidity,  25°C  (77°F) average temperature, wind velocity of  8
km/hr (5 m/hr) , and solar radiation of 353 kgcal/hr/sq mi (.130 BTU/hr/sq
ft), the equilibrium temperature in a cooling pond would be 32°C  (90°F).
With inlet temperature of 46°C  (115°F) and outlet  temperature  of 38°C
(100°F),  the  area  of the cooling pond would be 4100 sq m or about one
acre.  For 24-hour holdup time the depth of the pond must be 1.19  m  (3.9
ft) .  Such a pond would cost about $15,000  (1971-$)  (6)  and  should  be
adequate for the typical plant.

Piping Costs

Estimates of piping costs were made for the typical plant illustrated in
Figure  I by assuming that a cooling tower will be located near the kiln
area opposite the slurry tanks.  The total  length  of  piping  will  be
about 915 m (3000 ft), including 244 m (800 ft) from the raw mill  to the
finish  mill,  427  m  (1400  ft)  to connect the opposite ends of these
buildings (returns), and 244 m  (800 ft) for twelve 20.3  (66.7  ft)  runs
to  the  kiln  area  (feed  and  return  to 4 piers, burner pipe and gas
analyzer).

A rough fitting count includes 28-90° ells and 4 valves.  Allowances for
contingencies and 42 and 7 were used in calculating fitting costs.

Cost of piping was calculated on per lineal meter basis from Guthrie  (5)
assuming 0.23 m (8" schedule 40) pipe, a 0.61 m  (2 ft) wide by 1.83 m  (6
ft)  deep  trench,  machine  backfilled  with  hand  dressing.   Summary
follows:
       pipe  (materials
       pipe  (installation.
Cost/m
  15.25
Cost/lin ft
      5.00
                                  82

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         yard and offsite)      7.62             2.50
       trench (machine)         1.92              .63
       backfill 3 1.18/cu m
         (1.56/cu yd)            JL.10              ^69_
         Total                 26.89             8782/lin ft.

Cost of fittings from rough count including 50% contingency:

       42 ells material 3 $35.00 =      $1,470
       42 ells installed a) $11.50 =        483
        7 gate valves material a) $500.00 =
                                         3,500
        7 gate valves installed 2) $60.00_^_420
          Total fitting =               $5,873

Therefore,  total cost of installed piping is:

        pipe  915 x 26.89 = 24,622
        fitting             .,5*873
                           $30,495

To  allow  for finding and plugging existing lines, a 50% contingency is
provided to bring the total cost of piping at the plant to about $50,000
(1968 dollars).

Because a cooling pond may have to be located some distance say 1,000 ft
from where the cooling tower would have been, the cost of piping is the
same as for the cooling tower plus and additional 610m at 26.89 per
m. The cost of piping a cooling pond is therefore

             cooling tower piping      $50,000 plus
             610 m a $26.89/m           16,400
                    Total              $66,400  (#1968-$)

Containment of run-off from dust piles

Thirty-five plants report  an  average  of  0.156  metric  ton  of  dust
collected  per ton of product which for the typical plant amounts to 248
metric tons/day (273 ton/day).  The bulk density of  kiln  dust  may  be
estimated  as  1900  kg/cu  m  (117 Ib/cu ft) for a real density of 2400
kg/cu m (150 Ib/cu ft)  and 22% void  volume.   The  typical  plant  thus
collects  and,  in  the  extreme  case,  would pile 44,000 cu m per year
(57,000 cu yd).  With an angle of repose of about 37°,  a  conical  pile
2.4  hectares (6 acres) at the base and 65m  (200 ft) high will amount to
about 590,000 cu m  (700,000 cu yd)  or more than enough for 10 years use,
a square 2.4 ha (6 acre) site will leave a  perimeter  of  about  720  m
(2200  lineal  ft).   A  1.5 m (5 ft) high dike, 3 m  (10 ft) wide at the
base and 1.5 m (5 ft)  wide at the top will contain about 2400 cu m  (3100
cu yd)  which at $.91/cu m (7)  amounts to a construction costs  of  about
                                  83

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$2,000.   Allow  a contingency of 5056 and triple to provide a truck ramp
to a total of $10,000.  An adequate 3 m (10 ft) sluiceway  for  overflow
of  a  25 cm (10 m) 10" rain (extreme case) would add about $3,000 for a
total of $13,000 (1968-$) (7)  for a 2.4 ha  (6 acre)  containment  with  a
ramp and sluiceway.

To  handle  the  overflow  in  a  wet  climate  where  rainfall  exceeds
evaporation by 75 cm  (30 in)  per year, a  sulfuric  acid  neutralization
facility  could  be  installed for about $15,000.  Therefore, investment
cost of surface dust  pile  containment  for  the  typical  plant,  with
neutralization of excess runoff will cost about $30,000.


Stack Gas Carbonation and Settling of Leachate Stream

One  plant  reported that a 1962 cost of $175,000 to install a stack gas
carbonation system with  associated  thickener  and  clarifying  basins.
leachate  streams.    Adjustment  for size of typical plant and inflation
brings the 1971 investment cost to $260,000.

Operating costs are reported as approximately $15,000 per year.

Estimated Cost of Electrodialysis

    Assumptions used in estimating the cost of ED are as follows:

    Flow 757,000 I/day  (200,000 gal/day)
    K2.SOU to be removed = 1.209 eq/sec  (10 tons/day)

For technical details, Lacey & Loeb (30) should be consulted.

With the 85% efficiency given  in  Reference  30  the  electric  current
required is:

    1.209 eq/sec x (96500 amp sec)/(O.85)  = 137,000 amp

To  estimate  the  number  of  stacks required, a polarization parameter
(i/N, where i = current density and N = normality) of 250 (conservative)
will be assumed.  The current per cell pair is, therefore:

    300  (ma/sq cm)/(eq/l) x 0.11 eq/1 x 2600 sq cm/pair
    = 85.8 amp/cell pair

Since the total current is 137,000 amp, 1600 (137,000/85.8)   cell  pairs
are required, or 8 stacks of 200 cell pairs.

    Quotation from Aqua Chem, Inc. (January, 1971)

    WD-10-4 stacks (without membranes)
                                  84

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    50 cell pair stack $3,185 each
    100 cell pair stack $4,225 each

Therefore,  each  additional 50 cell pairs will cost $1,040.  A 200 cell
pair stack will cost $4,225 + 2,080 = $6,305.  If 8 stacks are  required
and  2  are  on  standby,  cost  will  be 10 x $6,305 or $63,050 without
membranes.

A suitable rectifier will cost about $13,500 (46).

Pumps will cost $5,400 (2 in service, 2 standbys at $1,350 each).

Membranes will cost no more than $37.70 sq m  ($3.50/sq  ft),  based  on
1970  quotations  from Tokuyama Soda Co., Ltd.,  of $18.85/sq m ($1.75/sq
ft) and from lonac Chemical Co., Inc. of $37.70/sq m ($3.50/sq ft).  The
cost of the 1598 sq m (17,200 sq ft) of membranes needed is $50,200.

Required sand filters will cost about $18,000.

The cost of a 13.72 m (45 ft) clarifier was quoted by Eimco, Inc., to be
$23,000.

It is estimated that a total of four turbo-agitated gas-contacting tanks
will be needed for the two stages of carbonation.  The cost of the  four
tanks is estimated to be $16,000 (34).

    Stacks         $63,050
    Membranes       50,200
    Rectifier       13,500
    Filter          18,000
    Pumps            5,400
    Secondary
         clarifier  23,000
    Carbonators     16T000
                  $189,150 Principal Items of Equipment  (PIE)

Erection  &  Assembly = 3056 of PIE or $56,745.  Contingencies of 10% PIE
and 10% E & A = 24,690 bringing the total to

    PIE       $189,150
    EGA       56,745
    Contin
    gencies     24^690
              $270,585
    Engineering 27^050
    (10X)
Total Investment for ED = $297,635  (1971-$)

Cost of Capital and Depreciation
                                  85

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Since the return on assets for the cement industry varies from 3 to  10%
and  the  interest  on  vorrowed  money  is  about Q%,  capital costs are
assumed at a straight 8% per year over a ten year period.   Depreciation
is on a 10 year straight-line basis.

Operating Costs

Operating  costs for ED will consist  of power,  replacement membranes and
labor.

At a stack voltage of 200 and a current  of  85.8  amps,  power  is  412
kwhr/day for ED, pumping will add about 60 kwhr/day.   In addition,  about
725 kwhr/day will be needed for the carbonators.

Some  manufacturers  of  membranes  guarantee  a  membrane life-time of 5
years for desalination, but a conservative  estimate   of  2  years   life
expectancy  was  assumed.   On  this   basis  the  annual cost of membrane
replacement is $25,100.  Labor is estimated at   100  man-hour/stack/year
or  about  1000  man-hours at $6.00/hr for a total labor of $6,000/year.
Annual operating cost of ED is therefore:

    330 days power at 12/kwhr $3,850


    Replacement of membranes and labor $3,850

    For a total annual operating cost of about
    $35,000 which is about 9% of the total
    investment for ED.
                                 86

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                         SECTION IX

       EFFLUENT REDUCTION ATTAINABLE THROUGH APPLICATION
     OF THE 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 (BPCTCA).  This technology is generally based upon the average
of  the  best  existing performance by plants of various sizes, ages and
unit processes within the industrial category or  subcategory  or  both.
This average is not based upon a broad range of plants within the cement
manufacturing  industry,  but  based upon performance levels achieved by
exemplary plants.  Consideration must be given to:

     a.  The total cost of application of technology in
         relation to the effluent reduction benefits to be
         achieved from such application.

     b.  The size and age of equipment and facilities involved.

     c.  The processes employed.

     d.  The engineering aspects of the application of
         various types of control techniques.

     e.  Process changes.

     f.  Non-water quality environmental impact (including
         energy requirements) .

Best  practicable  control  technology  currently  available  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
                                  87

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time of commencement of construction  or  installation  of  the  control
facilities.

Identification of,BPCTCA

Nonleaching Subcategory

For  the  nonleaching  subcategory  of  the  cement  industry,  BCTCA is
recycling and reuse of wastewaters and containment of runoff  from  coal
piles  and discarded kiln dust. An alternative to recycling and reuse is
the isolation of cooling water from possible sources  of  contamination.
In  any  case,  the  application  of  this  technology  will  result  in
essentially no discharge of pollutants.  To implement this requires:


     1.  Recycling of cooling water through the use of
         cooling towers, cooling ponds or completely
         closed package systems, or isolation of cooling
         water circuits from possible sources of con-
         tamination by the use of enclosures, and control
         of ambient dust within the plant, or reuse of
         cooling water for preparation of slurry in wet-
         process plants.

     2.  Containment and return-to-process of slurry spills
        and slurry tank wash waters at wet-process plants.

     3.  Installation of suitable dikes to contain runoff from
         coal piles and kiln dust piles or overflow from ponds
         where waste dust is slurried or neutralization and
         sedimentation of such runoff where it cannot normally
         be contained.

     4.  Recycling or evaporation of water used to slurry
         waste dust.

     5.  Storage piles of material other than high-alkali
         kiln dust should be suitably diked to prevent the
         discharge of pollutants to navigable waters in the
         event of a 10 year 24 hour rainfall event.

Leaching Subcategory

For the leaching subcategory, BPCTCA is reduction  of  suspended  solids
and  neutralization  of the leaching streams and application of the same
technology as outlined for plants in the nonleaching  category  for  the
remaining  streams.   Application of this technology, netrualization and
sedimentation should result in a suspended solids loading  of  not  more
than  0.15  kg/kkg  (0.30  Ib/ton) of dust leached, and a pH of not more
                                  88

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than 9.0.  Since the amount of dust leached rather than  the  amount  of
product  produced, determines water usage for these streams, limitations
on the leaching stream are expressed in these terms.

In addition to the implementation required for the nonleaching  streams,
implementation for the leaching streams requires:

      1.  Segregation of the leaching stream from all other
          streams.

      2.  Installation of suitable facilities to neutralize the
          leachate stream with stack gas to a pH of 9.0

      3.  Installation of a secondary clarifier or settling
          basin to reduce suspended solids to not more than
          0.15 kg/kkg (0.30 Ib/ton) of dust leached.

Limitations  resulting  from the application of this technology will not
result  in  a  reduction  in  total  dissolved  solids.   The  extensive
treatment  required  to  remove dissolved solids and the lack of current
practicable technology for treatment precludes setting  limitations  for
dissolved solids to be achieved by July 1, 1977.

Rationale_for_the_Selection_of_BPCTCA

Age and Size of Plants

As  discussed  in  Section IV, the age and size of a cement plant do not
bear directly on the quantity or quality of wastewater generated.

The age of a plant is not very meaningful because new  kilns  and  other
facilities may be added years after the original plant start-up.

Size  of  a  plant,  as  measured  by  rated capacity, is not applicable
because variations  in  the  type  of  equipment  and  plant  management
practices are reflected in widely varying water requirements.

These considerations, coupled with verification of exemplary performance
at  plants  of various sizes and ages, indicate that size and age do not
bear on the practicality of zero discharge of pollutants.

Total Cost of Application in Relation to Effluent
Reduction Benefits

Based on the information contained in Section VIII of this  report,  the
total  investment for all plants in the nonleaching subcategory would be
about $23,000,000 to achieve zero discharge of pollutants.
This figure is estimated on the basis of the known 151  plants  in  this
subcategory of which about 35 already report no discharge of pollutants.
                                 89

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For  the  remaining 116 plants the typical cost of $200,000 per plant is
assumed.  The 12 plants in the leaching subcategory will require a total
of about $5.1 million.  This includes the same per plant expenditures as
above plus an additional  $225,000  per  plant  for  neutralization  and
sedimentation facilities.

Thus, the estimated maximum expenditures for the industry as a whole are
about $28 million.   On a per-plant basis, cost will range from 0.5 to 2%
of  the  $20  to  $40  million  estimated average cost of building a new
plant.   The  anticipated  increase  in   operating   costs,   including
depreciation,  amounts  to  about $0.11 per metric ton of cement (with a
current reported cost of from $15.11 to $21.20 per metric ton).

Processes Employed and Engineering Aspects

All plants in the industry use the same or similar  production  methods,
giving  similar  discharges.  There is no evidence that operation of any
current process or subprocess will substantially affect capabilities  to
implement best practicable control technology currently available.

Engineering Aspects of Control Technique Applications

This  level  of technology is practicable because at least 23 percent of
the plants in the nonleaching subcategory are now achieving the effluent
reductions set forth herein.  The concepts are proved and available  for
implementation,  and  may  be  readily  adopted  through  adaptation  or
modification of existing production units.

Of the plants in the leaching subcategory, none is  presently  achieving
the  effluent  quality  that is specificed herein.  However, each of the
control techniques is presently employed at  individual  plants  and  in
proper  combination  could  achieve the prescribed effluent reduction if
applied at all plants in the leaching subcategory.

Process Changes

No process changes are envisioned for irrplementation of this
technology for plants in either subcategory.

Non-Water Quality Environmental Impact


The impacts upon non-water elements of the environment
include:

     1.  An increase in the solid wastes generated by the
         industry due to collected sludge

     2.  A potential limited effect upon ambient air quality
                                  90

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The former is relatively minor in view of -the large quantities  of  kiln
dust  presently  being  wasted.   The  latter arises because the cost of
implementing the control measures necessary at  leaching  plants  or  at
plants  that  slurry  discarded  dust may encourage these plants to pile
waste dust which can create localized dust problems on windy days.

The enhancement to water quality management provided  by  these  control
measures  substantially  outweighs  the  air  and  solids waste effects.
Moreover, techniques are available to control air-borne dust from piles,
and the solid wastes from this industry are  relatively  inert  and  are
acceptable  as  land  fill  and for uses such as sub-bases for secondary
roads and parking lots.
                                 91

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                          SECTION X

            EFFLUENT REDUCTION ATTAINABLE THROUGH
            THE APPLICATION OF THE BEST AVAILABLE
            TECHNOLOGY ECONOMICALLY ACHIEVABLE —
              EFFLUENT LIMITATIONS GUIDELINES


Introduction

The effluent limitations which must be achieved by July 1, 1983  are  to
specify   the  degree  of  effluent  reduction  attainable  through  the
application of the Best  Available  Technology  Economically  Achievable
(BATEA) .   This  technology  can  be  based on the very best control and
treatment technology employed by a  specific  point  source  within  the
industry  category  and/or  subcategory  or  technology  that is readily
transferable from one industry process to another.  A  specific  finding
must be made as to the availability of control measures and practices to
eliminate  the  discharge of pollutants, taking into account the cost of
such elimination.

Consideration must also be given to:

     1.  The age of the equipment and facilities
         involved

     2.  The process employed.

     3.  The engineering aspects of the application
         of various types of control technologies.

     4.  Process Changes

     5.  Cost of achieving the effluent reduction
         resulting from the technology.

     6.  Nonwater quality environmental impact
         (including energy requirements).

The Best Available Technology Economically Achievable also assesses  the
availability  in all cases of in-process controls as well as the control
or additional treatment techniques employed at the end of  a  production
process.   A  further consideration is the availability of processes and
control technology at the pilot  plant,  semi-works,  or  other  levels,
which  have  demonstrated  both  technological performances and economic
viability at a level sufficient to reasonably justify investing in  such
facilities.   Best  Available  Technology Economically Achievable is the
highest degree of control technology that has been achieved or has  been
demonstrated  to  be capable of being designed for plant scale operation
                                  93

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up to and including  no  discharge  of  pollutants.    Although  economic
factors are considered, the costs for this level of  control are intended
to  be  top-of-the-line  of  current  technology  subject to limitations
imposed  by  economic  and  engineering  feasibility.     However,   Best
Available  Technology  Economically  Achievable  may be characterized by
some technical risk with respect to performance and  costs and, thus, may
necessitate some industry development prior to its application.

Identification of BATEA

Nonleaching Subcategory

For  plants  in  the  nonleaching  contact  subcategory,  the   effluent
limitations  reflecting  this technology are essentially no discharge of
pollutants as developed in Section IX.

Leaching Subcategory

Based upon the information presented in Sections  III  through  VIII  of
this  report,   the  degree of effluent reduction attainable through the
application of BATEA is concluded to  be  essentially  no  discharge  of
process wastewaters to nayigable streams.

This  technology  consists  of  treatment  and  reuse  of water from the
leachate streams within  the  operation.   Implementation  requires  the
development  of  a practical system for the concentration and removal of
the alkali salts in the leachate stream.  Such  a  system,  outlined  in
Section  VII,  might  consist  of  electrodialysis,   evaporation,  or  a
combination of both.  While the technical and  economic  feasibility  of
these methods remains

to  be  demonstrated in this industry, the components of this technology
have been sufficiently demonstrated  to  justify  the  development  work
despite the technical and economic risks.
                                  94

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Rationale for Sglectipn of BATEA

For nonleaching plants, the rationale was developed
in Section IX.

For   leaching  plants,  the  effluent  limitation  of  "essentially  no
discharge" is based on the  availability  of  transferrable  technology,
electrodialysis.  While  this  technology is not presently in use in the
cement industry, it is considered the best  available  and  economically
achievable because:

     1.  It is currently is use on a commercial scale
         for recovery of salt from sea water, a more rigorous
         operation.

     2.  The total costs of implementing this technology,
         about $300,000 investments and $35,000 annual
         operating cost, appear to be within the range of
         economic, practicality in view of the pollution
         reduction benefits obtained.

     3.  The process appears to be technically sound as
         developed in Section VII.
                                  95

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                         SECTION XI

             NEW SOURCE PERFORMANCE STANDARDS
                AND PRETREATMENT STANDARDS


New Source^Performance Standards

A  new  source  is  defined as "any source, the construction of which is
commenced after the publication of proposed  regulations  prescribing  a
standard of performance."  Technology to be utilized for new sources has
been  evaluated by considering the control technology identified as Best
Available  Technology  Economically  Achievable   in   Section   X   and
considering  the  availability  of  alternative production processes and
operating methods.

The effluent limitation for new sources in the  nonleaching  subcategory
is  essentially  no  discharge  of  pollutants  to  navigable  waters as
developed in Section IX.  For leaching plants, the standard is reduction
of suspended solids to less than 0.15 kg/kkg (0.30  Ib/ton)  of  product
and pH to 9.0 as developed in Section IX.

The  technology  utilized  should  be  that  defined as Best Practicable
Control   Technology   Currently   Available.   After   the    necessary
developmental work is performed the technology defined as Best Available
Technology  Economically  Achievable  for leaching plants may eventually
provide a  more  effective  and  economical  treatment  system  and  the
performance standards should then be revised accordingly.

Pretreatment Standards

In  addition  to  the  effluent  limit for new sources, those wastewater
characteristics have been identified which would  interfere  with,  pass
through,  or otherwise be incompatible with a well designed and operated
publicly owned wastewater treatment plant.   A  determination  has  been
made  of  the  guidelines  for  the introduction of such wastes into the
treatment plant.
                                   97

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                       SECTION XIII

                        REFERENCES


                    CEMENT MANUFACTURING


1.  "The Making of Portland Cement," Portland Cement Association  (1964).

2.  "Portland Cements," Portland Cement Association  (1971).

3.  H. S. Frolich, "The Development of Cement Manufacture  in the Last 50
Years," Pit_and_Quarry_, 59, 301  (Oct., 1966).

4.  P. K. Mehta, "Trends in  Technology  of  Cement  Manufacture,"  Rock
Products^.      73, 83 (March, 1970) .

5.   J.  D.  Wilson,  Bendy  Engineering  Co.,  Letter to  G.A.  Morneau,
    Southern Research Institute, May 24, 1973.


        STATISTICAL AND COST DATA:  CEMENT INDUSTRY


6.  "U. S. Industrial Outlook 1972 with  Projections  to   1980,"  U.  S.
    Department of Commerce, 1972, p. 12.

7.   R.  A.  Grancher, "Cycling with Cement," Rock Products,75, 66  (Dec.
1972) .

8.  R. A. Grancher, "Cement's Second Century,"  Rock	Products, 7_4,  100
    (Oct. 1971) .

9.   Anon.,  "Cement:   Increase Anticipated for Cement Demand and  Plant
    Capacity Planning," Rock_Products, 74, 54  (Dec.  1971).

10.  "World cement Directory, 1972," International Publications Service,
    New York, 1972.

11.   "American  Cement  Directory  1972,"   Bradley   Pulverizer   Co.,
    Allentown, Pa.  (April, 1972).

12.   S.  Levine and E. W. Stearn, "The Year Ahead 1973,"  Rock Products,
    75X   53  (Deceirber,  ]9?2).                              	

13.  J. P. Wynen, "Economics of Cement Plant Design," Rock Products, 74,
    78  (Feb.  1971) and 74, 70  (March, 1971).
                                   101

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            KILN DUST UTILIZATION AND DISPOSAL


14.  B. Kester, "The Alkali Probelm," Presented to the  Portland  Cement
    Association, General Technical Committee,  (Fall, 1972).

15.   Anon.,  "Potash  from  Cement  at  the  Riverside  Portland Cement
    Company," Metallurgical and	Chemical_ Engineering, 701,   (June  15,
    1917).

16.   J.  M. Wolfe, "Kiln Dust-Properties and Handling," Pit and Quarry,
    55X. 136  (March, 2964) .                                             ~~

17.  C. H. Goller, Jr.,  "Is Dust Leaching Worthwhile," Pit and  Quarry,
    59A_122  (August, }966).

18.  W. R. Dersnah and C. F. Clausen, "Can that Dust be Used Again?" Pit
    and_2uarry., 50 (Sept.,  1958).

19.   T.  L.  McCubbin,  "Dust  Control Techniques for a Portland Cement
    Plant," Minerals Processing, 10, 24, (May, 1969).

20.  F. W. Cohrs, "How the Newer Plants Handle Kiln Dust Disposal," Rock
ProductSj^T^  	  50  (Nov., 1971).

21.  Termachos Patzias, "Extraction of Potassium Oxide from Cement  Kiln
    Flue Dust,"  Doctoral Dissertation, Wayne State University  (1959).

22.  G. C. Lindsay, "Don't Throw Away Dust," Rock Products,65, 87  (July,
    1962) .

23. "Panel Session on Dust Returned to Rotary  Kilns,"  Portland  Cement
    Association  (Jan., 1966).

           AIR AND WATER POLLUTION STUDIES:  CEMENT INDUSTRY

24.  "The Cement Industry:   Economic Impact of Pollution Control Costs,"
    Prepared by the Boston Consulting Group, for the U. S. Environmental
    Protection Agency  (Nov., 1971).

25.    "Background   Information  for  Proposed  New-Source'  Performance
    Standards:  Steam Generators, Incinerators, Portland Cement  Plants,
    Nitric  Acid  Plants,  Sulfuric  Acid  Plants,"  U. S. Environmental
    Protection Agency, Office of Air Programs  (Aug., 1971).

26.  "The Industrial Wastes Studies Program:  Summary Report on the Flat
    Glass,  Cement,  Lime,   Gypsum  and  Asbestos  Industries,"  U.    S.
    Environmental Protection Agency  (Jan., 1972).
                                   102

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27.    "Regional  Guidance for Permit Preparation:  Cement, Lime, Gypsum,
    Asbestos and Flat Glass Industries, U. S.  Environmental  Protection
    Agency (Sept. 21, 1972) .

28.    "Industrial Waste Study Report:  Flat Glass, Cement, Lime, Gypsum,
    and  Asbestos  Industries,"  Prepared  by  Sverdrup  &  Parcel   and
    Associates,  Inc.  for  the  U.  S.  Environmental Protection Agency
    (July, 1971).

29.   T. E. Kreichelt, "Atmospheric Emissions  from  the  Manufacture  of
    Portland Cement," U. S.  Department of Health, Education, and Welfare
    (1967).


              WASTEWATER CONTROL AND TREATMENT


30.   R. E. Lacey and S. Loeb, "Industrial Processing with
    Membranes," John Wiley and Sons, Inc., New York (1972).

31.   Henri Chidiac, "Water Pollution Control at Dundee's
    Clarksville, Mo., Plant," Pit and Quarry, 60, 86
    (Oct. 1968) .

32.   J. D. Wilson, "Controls Spark Waste Water Dilemna,"
    E2£fc_Products, 2£r 92 (March, 1973).

33.   G. Rey, W. J. Lacey, A. Cywin, "Industrial Water Reuse:
    Future Pollution Solution,"  Environmental Science^and
    Technology, 5, 763 (Sept., 1971).
34.   K. M. Guthrie, "Modern Cost Engineering Techniques,"
    McGraw-Hill Book Co., New York  (1970).

35.   W. L. Patterson, et.al., "Estimating costs and Manpower
    Requirements for Conventional Wastewater Treatment
    Facilities," U. S. Environmental Protection Agency
    (Oct., 1971) .

36.   "Pretreatment Guidelines for the Discharge of Indus-
    trial Wastes to Municipal Treatment Works," Prepared
     by Roy F. Weston, Inc.  for the U. S. Environmental Protec-
    tion Agency  (Nov. 17, 1972).


37.   "Commodity Data Summaries," U. S. Department of Interior, Bureau of
    Mines, pp. 114-115 (Jan., 1973).

38.   Chemical_Marketing_Re£orter, 203,  (Feb. 12, 1973).
                                  103

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39.    E.  L.  Quinn and C. L. Jones, "Carbon Dioxide," Reinhold Publishing
    Co.,  New York (1936).

40.   "Methods  for  Chemical  Analysis  of  Water  and  Wastes,"  U.  S.
    Environmental Protection Agency (1971).

41.    "Water  Measurement  Manual,"  U.  S.  Department of the Interior,
    Bureau of Reclamation  (1971).

42.  Japanese Patent 224611 (August 31, 1956), "Process for concentration
    of inorganic electrolyte solutions."

43.  Japanese Patent 217865 (November 28,  1955),  "Electro-dialyzer  for
    concentration of electrolytic solutions."

44.  Japanese  Patent   236354   (November   4,   1957),   "Process   for
    concentrating potassium salts."

45.  T. Nishiwaki, "Concentration of Electrolytes  Prior  to  Evaporation
    with  an  Electromembrane Process",  Chapter 6 in Industrial Processing
 	with	Membranes	,  R.  Lacey  and S. Loeb, editors,
    John  Wiley and Sons, Inc., New York (1972).

46.  Private  Communication, J. D.  Wilson, Bendy Engineering.

47.  Letter of J. D.  Wilson, Bendy Engineering to G. A. Morneau, Southern
    Research, May 24, 1973.

48.  "Marshall & Swift Annual Indexes  of  Comparative  Equipment  Costs,
    1953  to  1971," Chem.Eng;., Nov. 13, 1972, p. 170.

49.  Bruce Kester, private communication, Missouri Portland Cement Co.

50.  J. Perry (ed.),  "Chemical Engineers Handbook (3rd Edition)," McGraw-
    Hill  Book Co., New York, 1950.

51.  K. M. Guthrie, in "Modern Cost Engineering Techniques," Edited by H.
    Popper,  McGraw-Hill Book Co., New York, 1970.

52.  W. L. Patterson and R. F. Banker,  "Estimating  Costs  and  Man
                                                                  power
    Requirements  for  Wastewater Treatment Facilities," Final Report to
    EPA,  Contract 14-12-462, October,  1971.

53.  H. E. Mills, in "Modern Cost Engineering Techniques," Edited  by  H.
    Popper,  McGraw-Hill Book Co., New York, 1970.

54.  R. E. Lacey and  S.Loeb,  "Industrial  Processing  with  Membranes,"
    Wiley-Interscience, New York, 1972.
                                   104

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SECTION XIV

GLOSSARY


peg init ions and Terming logy


Alkali:  A substance having marked basic properties, generally sodium or
potassium oxides or hydroxides in kiln dust.
              A  quantitative  measure  of  the  capacity  of liquids or
suspensions to neutralize strong acids or to resist the establishment of
acidic  conditions.    Alkalinity   results   from   the   presence   of
bicarbonates,   carbonates,   hydroxides,  volatile  acids,  salts,  and
occasionally borates, silicates  and  phosphates.   Numerically,  it  is
expressed  in terms of the concentration of calcium carbonate that would
have equivalent capacity to neutralize strong acids.

B§.3._House :  A dust collection system in which the dust is  trapped  when
dust- laden air is passed through porous bags.

Bengf iciatign;   Improvement of the chemical or physical properties of a
raw  material  or  intermediate  product  by  removal   of   undesirable
components or impurities.

Blowdown:   A  periodic  discharge  to  prevent the buildup of dissolved
solids due to evaporative loss in cooling towers and boilers.

BOD __ .IBiochemical __ Oxygen __Demand^;   An   indirect   measure   of   the
concentration  of  biologically  degradable  material present in organic
wastes.  It is the amount of free oxygen utilized by  aerobic  organisms
when  allowed  to attack the organic matter in an aerobically maintained
environment at a specified temperature (20°C) for  a  specific  time  (5
days) .   It  is  expressed in milligrams of oxygen utilized per liter of
liquid waste volume  (mg/1) or in milligrams of oxygen  per  kilogram  of
solids present (mg/kg = ppm = parts per million parts) .
                                  105

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Burning:   Combustion  of  fuel,  or sintering or near-fusion in a kiln,
resulting in chemical combination of the raw materials and formation  of
clinker.

c§ffi§!lt__C-22.l£E:   Equipment  for cooling finished cement after grinding.
May consist of a  water-jacketed  screw  conveyor  with  a  water-cooled
impeller  schaft  and  blades,  or a vertical cylinder, with the outside
cooled by running water and along the inner  surface  of  which  a  thin
layer of cement is moved by centrifugal action.

Clarifier:   A  large  tank  or pond used for holding turbid water for a
sufficient time to allow solid materials to settle.

Clinker:  The fused product of a kiln which is ground to make cement.

COD jChemigal Oxygen Demand):   An indirect measure  of  the  biochemical
load exerted on the oxygen assets of a body of water when organic wastes
are  introduced  into  the  water.   It  is  determined by the amount of
potassium dichromate consumed  in  a  boiling  mixture  of  chromic  and
sulfuric acids.  The amount of oxidizable organic matter is proportional
to  the  potassium  dichromate  consumed.  Where the wastes contain only
readily available organic bacterial food and no toxic  matter,  the  COD
values can be correlated with BOD values obtained from the same wastes.

Cooling	Pond:   A  pond,  sometimes  equipped  with sprayers, used with
recycle cooling water systems to reduce the temperature of the water  by
evaporation.

Cooling	Tower:   A  mechanical  device,  normally  elevated,  used with
recycle cooling water systems to reduce the temperature of the water  by
evaporation.

Dissolved	Solids;   Solids  dissolved  in  water  and  not  removed  by
filtration.

Pry Process;  Process for cement manufacture in which the raw  materials
are ground, blended, stored, and conveyed to the kiln in a dry form.
                                 106

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Effluent:  The wastewater discharged from a point source (plant).

Electrostatic	Preqipitator:   Collector  for fine dust, particularly in
kiln gases.  Dust laden air is passed through a large chamber where  the
dust  particles  are ionized by contact with chains or rods connected to
one pole  of  a  high-voltage  rectifier,  and  then  attracted  to  and
collected  on  the  sides  of  tubes  or  plates  connected to the other
(grounded)  pole.  Collectors are rapped periodically to discharge dust.
Flocculation;  Accumulation or  agglomeration  of  fine  particles
masses or floes of suspended solids to facilitate settling.
            into
Gas_Analy_zer:  An instrument using the principle of chemical combination
or  catalytic  combustion  in which a sample of gas may be collected and
analyzed for oxygen, carbon dioxide and combustile materials.

Insufflation:  Practice of adding collected dust to the coal in a burner
pipe for return to the kiln.

Kiln:  A metal cylinder 2.5 to 8.5 m in diameter and  65  to  250  m  in
length,  slowly  rotating  (60 to 90 r.p.h.) and inclined approximately U
cm per m toward its discharge end:  for  burning  cement  raw  mix  into
clinker.   Lined  with refactory bricks and often equipped with internal
heatexchangers.
Kiln_Dust:  Fine particles of cement and raw materials
kiln and collected by air-pollution control equipment.
blown  from  the
           The overflow discharged from a leaching operation.

Leaching:   A  process  for  removing alkalies from kiln-dust by washing
with water, so that the dust can be reused to make cement.

Loading;  The quantity of a constituent added to the water used within a
point source and subsequently discharged, normally expressed  in  amount
per unit of production.
                                  107

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Outfall:   A  point  at  which  the  effluent  from  a  point  source is
discharged into a navigable waterway.

Overflow;  Excess water from an operation, tank,  pond,  etc.   that  is
recycled or discharged, generally after settling of suspended solids.

p.H;   The symbol for the logarithm of the reciprocal of the hydrogen ion
concentration, expressed in moles per liter of a solution, and  used  to
indicate  an  acid or alkaline condition.  (pH 7 indicates neutral; less
than 7 is acid; greater than 7 is basic).

Portland^Cement;  The product obtained by pulverizing clinker consisting
essentially of hydraulic calcium silicates, to which no  additions  have
been  made  subsequent  to calcination other than water and/or untreated
calcium sulphate, except that additions not to  exceed  1.0  percent  of
other materials may be interground with the clinker at the option of the
manufacturer, provided such materials in the amounts indicated have been
shown to be not harmful by tests carried out or reviewed by committee C-
1 on Cement of the American Society for Testing Materials (A.S.T.M.).

Process^. Water;   A general term applied to the water used in operations
directly  related  to  the  manufacture  of  a  product,  and  sometimes
contacting  the  product or raw materials, as distinguished from cooling
water, boiler water, and all other water used in  ancillary  operations.
In  cement manufacturing the term is most commonly applied to the slurry
water used at wet-process plants.

RAPP Applications:  Applications submitted to the Corps of Engineers  to
obtain  a  Permit  for  Discharge  into  Navigable Waters under the 1899
Refuse Act Permit Program.

Recycled Water;  Water which is recirculated for the same use.

Reused Water;  Water which is used for one purpose and then  reused  for
another purpose.
                                  108

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Sedimentation;   The removal of suspended solids contained in wastewater
that will separate by settling when the carrier  liquid  is  held  in  a
quiescent condition for a specified time interval.

Settling	Basin:  A pond, lagoon, or tank also referred to as holding or
sedimentation basin in which suspended solids are removed  sometimes  by
the addition of flocculants.

Sludge:   The  accumulated  settled  solids deposited from the sewage or
other wastes, raw  or  treated,  in  tanks  or  basins,  and  containing
sufficient water for form a semiliquid mass.

Slurry.:   Suspension  of  ground  raw  materials in water at wet-process
plants.

Su§_£ended_Solids:  Solids that either float on the surface of, or are in
suspension in, water and which are largely  removable  by  filtering  or
sedimentation.

Thickener:   Large  basin for slurry of raw materials ground with excess
water.   Suspended  particles  settle  to  bottom  (underflow),  whereas
surplus water (overflow) runs over edge.

Total Solids:  The residue remaining when the water is evaporated from a
sample  of water, sewage, other liquids or semi-solid masses of material
and the residue is  then  dried  at  a  specified  temperature  (usually
103°C).

Underflow:   Carrier  water  used in an operation to transport solids to
another operation or disposal site.

Volatile_Solids:  That portion of the total or suspended solids  residue
which  is  driven  off  as  volatile  (combustible)  gases at a specified
temperature and time (usually at 600°C for a least one hour).

Waste-Heat_Boiler;  System of boilers and economizers, heated by the hot
exit gases from kilns, used to generate electricity.
                                  109

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Waste Load;   The  quantity  of  a  constituent  present  in  wastewater
expressed  in units of concentration, amount per day, or amount per unit
of production.  Raw waste load is the quantity of a given constituent in
the wastewater prior to treatment.  Net waste  load  is  the  difference
between  the  quantity  of  a  constituent  in  the intake and discharge
waters.

Wet ^Process;   Grinding,  blending,  mixing  and  pumping  cement   raw
materials  mixed  with water.  Wet process is chosen where raw materials
have a high water content, which would make drying before  crushing  and
grinding difficult.

Wet	Scrubber:   Type  of  dust  collector in which dust-laden gases are
cleaned by passing through a fine spray of water.
                                   110

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