p. 1



# OAR Box 

# 1828 Prepped by Ollie Stewart



### Document

Number: 

# 321 ) IV-B-2 5 Docket Number: 

# A-83-2 7

Printed 11/12/2008 11:12:59 AM Sheet 321 of 325P. 2 

# A-83-2 7

CORPORATIO N

MEMORANDUM IV-B-2 5

DATE : Jun e 22 , 198 7 TO : Wal t Stevenson , EPA/OAQPS/ESE D FROM : Davi dWhite , Radia nCorporatio n SUBJECT : Sulfu r Reductio nPotentia l o f Advance dPhysica l Coa l

Cleanin g Technologie s

1. 0 INTRODUCTIO N
Th e term "physica l coa l cleaning " (PCC ) cover s a larg e numbe r o f technique s use dt o separat e as han d sulfu r fro

m as-mine dcoa l prio r t o 1 2 combustion . ' Th e abilit y t o remov e as han

d sulfu r b

y PC C depend s o

n th e washabilit y

o f th e coa l (whic hi s a functio no f th e mod e o f physica l occurrenc e o f thes e impuritie s withi nth e coal) , th e leve l o f coa l crushin g an

d grindin g use dt o liberat e thes e material s from th e coa l prio r t o actua l cleaning , an d th e typ e o f cleanin g technolog y used . Almos t al l conventiona l PC C processe s us e a separatin g flui dt o floa t th e lighte r organi c materia l i n coa l (havin g a typica l specifi c gravit y o f 1.2-1.3 ) fro

m th e heavie r impuritie s (s.g.=2.0-5.0) . Th e lowe r th e specifi c gravit y o f th e separatin g fluid , th e lowe r th e as h an dsulfu r conten t o f th e cleane dcoal . Wit hsome highl y washabl e coal s (e.g. , some o f th e high-sulfu r coal s fro m Norther nAppalachia ) commercia l PC C processe s ca n reduc e a coal' s SO - emissio nrat e (i.e. , l bSOp/mi1 1 io

nBtu ) b

y roughl y 5 0 percent . However , fo r mos t coals , SO - reduction s achievabl e wit hexistin g PC C processe s ar e les s tha n3 0 percent . Thi s mem o examine s th e sulfu r reductio npotentia l o f advance d physica l coa l cleanin g (APCC ) processe s currentl y unde r developmen t b

y 3 4 th e U.S . Departmen t o f Energ y (DOE ) an

d privat e industry . ' O f

Progres s Center/320 0 E

. Chape l Hil l Rd./Nelso n Hwy./P.O

. Bo x13000/Researc h Triangl e Park

. N.C

. 27709/(919)541-9100P. 3

specifi c interes t ar e th e abilit y o f APC C t o 1 ) decreas e SO - emission s b y 9 0 percent , an

d2 ) yiel dver y

low-sulfu r coal s wit ha nSO - emissio n rat e o f les s tha n1. 2 lbs/millio nBtu . Chemica l an dbiologica l processe s fo r removin g sulfu r fro m coa l ar e als o unde r development , bu t ar e no t expecte dt o be o f commercia l significanc e withi nth e nex t 5-1 0 years . Becaus e o f thei r limite dnear-ter m commercia l significance , the y

ar e no t discusse dfurthe r inthi s memo . Th e mem o i s divide dint o fou r section s coverin g 1 ) th e importanc e o f mode s o f sulfu r occurrenc e incoa l onsulfu r remova l durin g PCC , 2 ) th e desig no f APC C processes , 3 ) th e leve l o f sulfu r reductio n achievabl e wit hAPC C processes , an d4 ) th e impac t o f APC C processe s on th e potentia l fo r productio no f ver y low sulfu r coals . 2. 0 MODE S O F SULFU ROCCURRENC E I N COA L
Sulfu r occur s incoa l inthre e basi c forms : organic , pyritic , an dsulfate . Organi c sulfu r i s chemicall y boun dt o th e organi c structur e o f coal . Becaus e o f thi s chemica l bond , physica l cleanin g method s ar e ineffectiv e a t removin g organi c sulfur . Inmos t U . S . coals , organi c sulfu r account s fo r 0. 3 t o 1. 5 percen t o f th e tota l weigh t o f th e coal . Thi s correspond s t o u pt o 8 0 percen t o f th e tota l sulfu r i nsom e low

sulfu r coals , bu t ca nb e a s littl e a s 2 5 percen t o n th e tota l sulfu r i nsome hig hsulfu r coals . Sulfat e generall y represent s les s tha n0. 1 weigh t percen t an dha s littl e impac t ontota l sulfu r level s (th e majo r exception s i nth e U . S . ar e i nth e Interio r an dNorther nGrea t Plain s region s wher e level s o f upt o 0. 5 percen t ca noccur) . Pyriti c sulfu r occur s i ncoa l a s discret e particle s o f pyrit e an d marcasit e (bot ho f whic har e minera l polymorph s o f iro nsulfide , FeS- ) an dt o a lesse r exten t a s sulfide s o f copper , zinc , an dlead . Thes e minera l particle s ca nrang e from microscopi c grain s disperse d throughou t th e coa l matri xt o larg e fragment s severa l inche s across . Inmos t U.S . coals , pyriti c sulfu r range s fro m 0. 1 t o 5. 0 weigh tP. 4

percent . O na relativ e basis , pyriti c sulfu r ca nrang e fro m 2 0 percen t t o 8 0 percen t o f th e tota l sulfu r content ; th e low en do f thi s rang e i s generall y

associate dwit hcoal s tha t ar e als o low inorgani c sulfu r whil e th e highendi s generall y foundincoal s tha t ar e highin organi c sulfur . Th e abilit y

t o separat e pyriti c sulfu r fro m coa l depend s o

nbot h th e physica l siz e o f th e sulfid e particle s an dthei r distributio n throughou t th e coa l matrix . I ngeneral , smal l sulfid e particle s ar e harde r t o remov e tha nlarg e particles . Existin g coa l cleanin g methods , mos t o f whic har e limite dt o cleanin g coal s tha t hav e bee n crushe dt o a particl e siz e o f 2 8 mesh * an dlarger , ar e capabl e o f removin g almos t al l o f th e pyriti c sulfu r tha t occur s a s fairl y large , discret e nodules . However , sulfid e particle s smalle r tha nthi s siz e remai nattachedt o th e lighte r organi c fractio nan dar e mor e difficul t t o remove . B

y usin g separatin g fluid s wit hlow specifi c gravitie s (e.g. , s.g.=1.3-1.4) , additiona l amount s o f pyrit e ca nb e removed . A t thes e low

specifi c gravities , however , a significan t portio no f th e origina l heatin g conten t o f th e coa l i s als o lost , thu s resultin g i n unfavorabl e economics . A s a percentag e o f th e tota l sulfu r incoal , sulfu r reduction s economicall y achievabl e wit hconventiona l PC C processe s rang e fro

m nea r zer o (fo r as-minedcoal s inwhic hpyrit e conten t i s alread y

low ) upt o roughl y

5 0 percent .
3. 0 ADVANCE D PHYSICA L CLEANIN GPROCESSE S
Researc han

ddevelopmen t effort s ar e underwa y b y DO E an dprivat e industr y t o develo pAPC C processe s capabl e o f removin g greate r amount s o f fine-graine dpyrite . T o achiev e thes e highe r remova l efficiencies ,

* Mes hsize s ar e use dt o defin e th e siz e o f particle s abl e t o pas s throug ha wir e scree no f define dspacin g betwee nwires . Mes hsize s use dinthi s mem o an

dcorrespondin g particl e size s are : 1 4 mes h= 1.1 9 m

m (0.046 9 inches) , 2 8 mes h= 0.59 5 m

m (0.023 4 inches) , 10 0 mes h= 0.14 9 m

m (0.005 9 inches) , and 20 0 mes h= 0.07 4 m

m (0.002 9 inches) .P. 5

th e coa l i s groun dt o particl e size s smalle r tha nconventiona l PC C processe s ca nhandl e (i.e. , 2 8 mesh) . Some APC C processe s hav e bee n teste da t particl e size s o f 20 0 mes han dsmaller . Thi s additiona l grindin g allow s mor e complet e separatio no f particle s containin g fine-graine dpyriti c sulfu r an das hfro

m those containin g mainl y coal . However , a t these smal l particl e sizes , PC C method s base dsolel y o n differentiatin g th e specifi c gravit y o f particle s ar e relativel y ineffectiv e du e t o constraint s associate dwit hbot hth e physic s o f smal l particle s an

dth e cos t o f handlin g finel y groun dmaterial . T o overcom e thes e limitations , APC C processe s us e a variet y o f tech niques , includin g heav y organi c compound s combine dwit hcentrifuga l force , alteratio no f surfac e propertie s throug hus e o f surfactants , an dus e o f difference s inth e magneti c an delectrostati c properties . Tabl e 1 summarize s severa l advance dphysica l coa l cleanin g processes . Becaus e APC C processe s ar e expecte dt o b e two - t o three-time s mor e expensiv e pe r tono f cleane dcoa l tha nexistin g PC C processes , mos t advance dcleanin g processe s ar e envisione da s par t o f a ninte grate dcleanin g plan t inwhic hmateria l large r tha n2 8 mes hi s cleane d usin g conventiona l processe s followe db y furthe r crushin g an dAPC C o f a portio no f th e plant' s tota l throughpu t a s neede dt o mee t coa l produc t specifications . B y combinin g conventiona l an dadvance dPC C processe s int o a singl e plant , i t i s possibl e t o operat e th e conven tiona l equipmen t a t lowe r specifi c gravitie s tha nwoul dotherwis e b e economica l i norde r t o recove r a ver y low as han dsulfu r product .
4. 0 SULFU RREDUCTIO N POTENTIA L O F APC C

A s discusse dabove , th e performanc e o f APC C processe s relativ e t o conventiona l processe s i s dependen t upo nth e liberatio no f additiona l pyrit e a s a resul t o f fine r grinding . I nconcept , th e fine r th e grind , th e mor e complet e th e separatio no f pyriti c sulfu r fro m coal . A s discusse dearlier , however , non e o f th e physica l cleanin g processes—whethe r conventiona l o r advanced—ar e abl e t o remov eTABL E 1. . DESCRIPTIO N OF SELECTE D APC C PROCESSE S


### EBQCESS .
Heav y Medi a Cyclon e (HM O

Advance d Flotatio

n

Heav y Liqui d

Electrostati c Separatio

n

01 1 Agglomeratio

n 

### DESCRIPTIO N

Use s finely

groun d magnetit e (32 5 mesh ) disperse d 1 n wate r t o produc e a hig hspecifi c gravit

y fluid . Separatio

n o f sulfu

r an d coa l 1 s enhance d b y centrifuga l force s produce d 1 n cyclone . Use

d o n 2 8 X15 0 meshmaterial . Multipl e vendors .

Use s finely

divide d bubble s an

d surfactant s t o selectivel y remov e as han d pyrit e 1

n sequentia l cleanin g steps . Use

d o n 10 0 X0 mesh material . Developer s includ e BCRNL , Bechtel , Michiga n Tech .
Use s heav

y organi c liquid s (e.g. , freon , perchloroethylene ) an d cyclone s t o separat e coal fro m as han d pyrit e base

d o n specifi c gravity . Som

e heav y liquid processe s als o us e agglomeratio n a s a precleanin

g ste p t o separat e hydrophobi c coa l fro m hydrophili c clay . Use d o n 10 0 X0 meshmaterial . Developer s Includ e Do w Chemica l an

d Otlsca .
Use s difference s 1

n electrostati c propertie s o f nonconductiv e coa l versu s conductiv

e pyrit e an

d as ht o collec t coa l o n a n electricall y charge d drum . Tw

o different variant s o f proces s exist , on e fo r 2 8 X40 0 mesh"fine " coa l an d the othe r fo

r 14 0 X0 mesh"ultraflne " coal . Develope

d b y Advance

d Energ y Dynamics .
Use s fue l oi l or othe r solvent s t o selectivel y coa t an

d agglomerat e hydrophobi c coal . Use d o n 10 0 X0 mes hmaterial . Developer s includ e Nationa l Researc

hCounci l o f Canada , Otlsca , an d University

o f Pittsburgh .

T JP. 7

organi c sulfu r regardles s o f how finely th e coa l i s ground . A s a result , SO - reduction s fro m a coa l containin g hal f pyriti c sulfu r an d hal f organi c sulfu r ar e a t mos t 5 0 percent . Tabl e 2 present s dat a o nsulfu r remova l versu s coa l particl e siz e an dBt urecover y

fo r severa l majo r U . S . coa l seams . Whil e washabilit y

dat a doe s no t directl y translat e t o sulfu r removal s wit h specifi c cleanin g processes , the y d o giv e a

nindicatio no f th e relativ e significanc e o f additiona l grindin g an dBt urecovery . Fo r th e liste dcoals , th e additiona l SO - reductio nachieved(a t 9 0 percen t Bt urecovery ) b

y reducin g particl e to psiz e fro m 3/ 8 inc h(comparabl e t o particl e to psize s insevera l conventiona l processes ) t o 1 4 mes h (close r t o tha t use dinconjuctio nwit hadvance dprocesses ) range s from 2 t o 7 percent . Dependin g onth e mod e o f pyrit e occurrenc e ina n individua l coal , grindin g t o smalle r particl e size s (e.g. , les s tha n 10 0 mesh ) ma y

liberat e additiona l sulfu r fro m some coals . Th e "7 0 percen t Bt urecovery , -1 4 mesh " colum ni s a napproximatio no f th e practica l uppe r limi t o nSO - reductio nachievable ; fo r th e Norther n Appalachi a an

dIllinoi s Basi ncoals , thes e SO - reduction s correspon d t o removin g 7 5 t o 9 0 percen t o f th e pyriti c suluf r i nth e as-receive d coal . APC C processe s ma y b e abl e t o achiev e comparabl e SO - reductio n whil e recoverin g a highe r percentag e o f th e origina l Bt ucontent . Tabl e 3 present s dat a from test s onthre e Norther nAppalachia n coal s usin g severa l differen t APC C processe s discusse dinTabl e 1 . Not e th e variabilit y

inperformanc e achievedwit hdifferen t processes , indicatin g th e sensitivit y o f thes e processe s t o coa l specifi c characteristics . Inclusio no f th e Uppe r andLowe r Freepor t seam s i n thi s tabl e i s significan t becaus e the y ar e generall y

amon g th e mos t highl y washabl e coal s inth e U . S . Maximu m SO - reduction s wit heac h coa l rang e from

4 9 percen t fo r th e Pittsburg hseam t o 7 7 percen t wit h th e Lowe r Freeport . Direc t compariso no f dat a fro m Table s 2 an

d3 fo r th e Pittsburg h andth e two Freepor t seam s inno t possibl e becaus e o f differenc e i n as-receive dcoa l characteristic s fo r th e evaluate dsamples . However ,TABL E 2 . S0 2 REDUCTIO N VERSU S PARTICL E SIZ E AN D BT URECOVER

YBASED O

N WAHABILIT

YDAT A FO R SELECTE

D U.S . COALS 3

Coa l Reg1on/Sea

m
Norther n Appalachi a Pittsburg

h Uppe r Freepor t Lowe r Freepor t Uppe r K1ttan1n

g M1d/Lo w K1ttan1n

g
Souther n Appalachi a
Illinoi s Basi n

Wester n Interio

r

Wes t RO M

5. 8 3. 9 3. 6 3. 5 4. 8
1. 6
6. 5
9. 0
1. 1 90 % 

### - I 1 

### / *

4. 2 2. 3 2. 1 1. 8 2. 8
1. 3
4. 2
6. 2
0. 8 —

lh^ O /MUn+ n Bt u Recover

y 

### =!/f i -1 4 Mes h

3. 9 3. 6 1. 9 1. 6 1. 5 1. 4 1. 5 1. 4 2. 3 2. 2
1. 2 1. 2
4. 1 4. 0

5. 9 5. 8
0. 9 0. 8 705 6



### -1 4 Mes h

3. 0 1. 2 1. 1 1. 1 1. 8
1. 2
3. 5
4. 6

0. 8 90 * 

## -lV 2

2 6 3 9 4 0 4 3 3 8
1 5
3 4
3 0
15 Btu Recover

y

- 3 / 8 -1 4 Mes h

3 1 3 8 5 0 5 7 5 6 6 2 5 0 5 2 4 4 4 7

1 6 1 8

3 5 3 8

3 5 3 8

1 5 1 9 70 S



### -1 4 Mes h

4 7 6 5 6 8 5 9 5 4
1 9
4 5
5 2

2 3

-l 1 / ? = I 1 /? " • - 3 /f l = 3 /fl « Actua l particl e sizes : -1V 2 = 1V2 " X10 0 mesh ; - / 8 = J /8 " X10 0 mesh ; -1 4 mesh= 1 4 meshX0
Referenc e 5TABL E 3 . S0 2 REDUCTION PERFORMANC E FO

R SELECTE D APC C PROCESSE S

0 0 Pittsburg h l bS0 2 /M M Btu XS0 2 Reductio

n XBtu Recover

y
Uppe r Freepor t l bS0 2 /M M Bt u XS0 2 Reductio

n XBtu Recover

y

Lowe r Freepor t l bS0 2 /M M Btu XS0 2 Reductio

n XBtu Recover

y 

### RO

M 

### F£E £

5. 6

—



### 4. 7

—



### 7. 5 HMC / 

### FLOTATION

3. 2 4 3 8 9

1. 8 6 3 8 6

2. 1 7 2 8 4 ADVANCE

D 

### FLOTATION

3. 4 3 9 8 9

2. 1 5 5 9 3

2. 6 65 8 9 HEAV

Y LIQUI D



### 3. 1 4 4 9 2

1. 6 6 6 8 9

2. 0 7 4 8 7 ULTRAFIN

E 

### ELECTROSTATIC S

2. 8 4 9 9 4

1. 1 7 4 9 2

1. 7 7 7 9 0 OI

L 

### AGGLOMERATION

3. 7 34 9 2

2. 3 5 2 9 0

2. 9 6 1 9 0

a Se e Tabl e 1 fo r descriptio no f Processe s Referenc e 3P.1 0

fo r th e Pittsburg hsea m (fo r whic htota l sulfu r level s o nbot htable s ar e similar , bu t no t necessaril y th e spli t betwee norgani c an d puriti c sulfur) , severa l o f th e APC C processe s wer e abl e t o achiev e 5 t o 1 0 percen t greate r SO - reduction s tha nshow ninth e "9 0 percen t Bt u recovery , -1 4 mesh " colum no f Tabl e 2 . Thes e SO - reduction s ar e comparabl e t o th e chang e inTabl e 2 betwee n7 0 an d 9 0 percen t Bt u recover y wit h-1 4 mes hcoal .
5. 0 US E O F APC C T O PRODUC E VERYLO W SULFU RCOAL S
Eve ni f al l o f th e pyriti c sulfu r coul d b e remove d b y APC C processes , a

nSO - emissio nlimi t o f 1. 2 lb/millio nBt u woul d requir e a coa l wit hles s tha nroughl y 0. 7 percen t organi c sulfu r (assumin g a coa l heatin g valu e o f 11,70 0 Btu/lb) . A t a emissio nrat e o f 0. 8 l b SO-/millio nBtu , th e maximu m organi c sulfu r leve l i s 0. 5 percent . Coal s wit hthes e lo

w organi c sulfu r level s ar e found primaril y inth e Pottsvill e Formatio no f Alabama , easter nKentucky , souther nWes t Virginia , an

d Virginia ; th e Freepor t an d Kittanin g seam s o f Ohio , Pennsylvania , an

d norther nWes t Virginia ; an d variou s wester ncoal s fro m Colorado , Montana , Nort hDakota , Utah , an d Wyoming . Becaus e many o f thes e wester ncoal s hav e pyriti c sulfu r level s o f les s tha n0. 1 percent an

d as-mine d SO - emissio nrate s below 0. 8 lb/millionBtu , coa l cleanin g woul d b e o f limite d value . Thi s section , therefore , focuse s o ncoal s fro

m Norther nan

d Souther nAppalachia . A s show ninTabl e 2 , cleane d coal s fro m severa l majo r seam s in thes e region s hav e averag e SO - emissio nrate s a t o r slightl y abov e 1. 2 lb/millio nBtu . However , some individua l coal s hav e lowe r sulfu r content s o r ar e mor e washabl e tha nthes e averag e values . T o estimat e th e potentia l fo r producin g ver y low sulfu r coals , washabilit y dat a in Referenc e 5 wa s reviewed . A threshol d valu e o f 1. 2 l bS0-/millio nBt u a t 7 0 percent Bt u recover y an d a 1 4 mes hto p siz e wa s use d t o estimat e SO - reduction s possibl e wit hAPCC . A to p siz e o f 3/ 8 inc han d 9 0 percen t Bt u recover y

wa s use d t o represen t conventiona l PC C processes .Coa l seam s o f interes t i nNorther nAppalachi a ar e th e Uppe r and Lowe r Freepor t an

dth e thre e member s o f th e Kittaning . Base don coa l sample s collecte dfro m thes e seam s i nPennsylvania , roughl y 6 0 percen t o f th e Freepor t coal s an d2 0 percen t o f th e Kittanin g coal s mee t o r excee dth e 1. 2 l bcriteri a fo r APCC . Wit hconventiona l PC C processe s (i.e. , a t 9 0 percen t Bt urecovery) , th e percentage s fo r eac h se t o f seam s decrease s t o roughl y 2 0 an d1 5 percent , respectivley . Th e lowes t SO - emissio nrat e wit hAPC C i s roughl y 0. 8 lb/millio nBt u fo r bot hset s o f seams . Wit hconventiona l PC C th e lowes t emissio n limi t i s roughl y

0. 9 lb/millio nBtu . Percen t reduction s inS0 - emission s associate dwit hcleanin g thes e coal s range fro m 5 0 t o 7 0 percen t fo r bot hPC C an dAPCC . InSouther nAppalachia , th e coal s fro m Virgini a wer e examined . Al l o f th e Virgini a coal s liste dinReferenc e 5 achiev e SO - emissio n rate s o f 1. 2 lb/millio nBt uo r lowe r a t 9 0 percen t Bt urecover y (i n5 o f th e 8 sample s listed , th e 1. 2 l bleve l wa s me t withou t washing) . Th e lowes t SO - emissio nrat e a t bot h7 0 an d9 0 percen t Bt urecover y i s roughl y 0. 8 lb/millio nBtu . Becaus e mos t o f thes e sample s hav e as-receive dpyriti c sulfu r level s o f les s tha n0. 3 percent , S0 - reduction s associate dwit hcleanin g wer e generall y les s tha n2 0 percent . Base donth e above discussion , th e potentia l fo r APC C processe s t o produc e ver y

low sulfu r coal s appear s limite dt o specifi c coal s whic har e inherentl y

low i norgani c sulfur . Base donth e dat a reviewed , us e o f APC C ha s th e potentia l t o expan dth e suppl y o f Norther nAppalachia ncoal s wit hles s tha n1. 2 l bS0-/millio nBtu , bu t doe s no t appea r likel y t o significantl y

increas e th e suppl y o f thes e coal s wit hles s tha n0. 8 l bS0-/mil1io nBtu . Becaus e o f th e lo w pyriti c sulfu r conten t i nothe r lo w sulfu r coals , suc ha s thos e fro m Souther nAppalachi a an dth e West , th e potentia l impac t o f APC C onver y low sulfu r coa l suppl y

appear s small .



### 1 0P.1 2

6. 0 REFERENCE S

1 . Kilgroe , J . D . and J . Strauss . Coa l Cleanin g Option s fo r S0

- Emissio n Reduction
. Powe r Magazin e Conferenc e o f Aci d Rain , Washington , D . C , 1985 , 5 3 pp . 2 . Holt , E . C . A n Engineering/Economi c Analysi s o f Coa l Preparatio n Plan t Operatio n an

d Cost . EPA-600/7-78-124 , U . S . Departmen t o f Energ yand U . S . Environmenta l Protectio n Agency , Washington , D . C , 1978 , 29 6 pp . 3 . Boron , D . J. , M . P . Matoney , and M . C . Albrecht
. Advance d Physica l Coa l Cleaning : An Evaluatio n o f Fiv e Selec t Processes . Proceeding s o f th e Thir d Annua l Pittsburg h Coa l Conference , Universit yo f Pittsburgh , Septembe r 8-12 , 1986 , pp . 13-18 . 4 . Cavallaro , J . A. , R . P . Killmeyer , A . W . Deurbrouck , and K . Rhee
. A n Overvie wo f PETC' s Chemical , Physical , and Surface-Enhance d Beneficiatio n Program . Pittsburg h Energ yTechnolog yCenter , U . S . Departmen t o f Energy , 1986 , 2 9 pp . 5 . Cavallaro , J . A. , M . T . Johnston , and A . W . Deurbrouck
. Sulfu r Reductio n Potentia l o f th e Coal s o f th e Unite d States . R I 8118 , U . S . Burea u o f Mines , Pittsburgh , Pennsylvania , 1976 , 32 3 pp . Hucko , R . E. , Pittsburg h Energ yTechnolog yCenter . A n Overvie wo f U.S . Departmen t o f Energ yCoa l Preparatio n Research
. Societ yo f Minin g Engineer s o f AIME , Preprin t Numbe r 84-105 . 5 . Hucko , R . E. , Pittsburg h Energ yTechnolog yCenter . Recen t Initiative s i n Coa l Cleanin g Researc h a t th e U.S . Departmen t o f Energy . Societ yo f Minin g Engineer s o f AIME , Preprin t Numbe r 86-56 . 6 . Simmons , Frederic k J. , and Dougla s V . Keller , Jr. , Otisc a Industries , Ltd. , Two Ton-per-da yProductio n o f Otisc a T-Proces s Ultra-Clea n Coal/Wate r Slurry , 10t h Internationa l Coa l Preparatio n Congress , Septembe r 1-5 , 1986 . 7 . Keller , Dougla s V. , Jr. , Otisc a Industrie s Ltd. , telephon e conversatio n wit h Edwar d Moretti , Radia n Corporation , Decembe r 8 , 1986 .



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