Paper Number:DOE/MC/30056-97/C0754

Title:Utilization of Lightweight Materials Made from Coal Gasification Slags

Authors:V. ChoudhryS. Hadley

Contractor:Praxis Engineers, Inc.852 North Hillview DriveMilpitas, CA 95035

Contract Number:DE-FC21-94MC30056

Conference:Advanced Coal-Fired Power Systems '96 Review Meeting

Conference Location:Morgantown, West Virginia

Conference Dates:July 16-18, 1996

Conference Sponsor:U.S. DOE, Morgantown Energy Technology Center

Disclaimer

This report was prepared as an account of work sponsored by anagency of the United States Government. Neither the United StatesGovernment nor any agency thereof, nor any of their employees,makes any warranty, express or implied, or assumes any legal liabilityor responsibility for the accuracy, completeness, or usefulness of anyinformation, apparatus, product, or process disclosed, or representsthat its use would not infringe privately owned rights. Referenceherein to any specific commercial product, process, or service by tradename, trademark, manufacturer, or otherwise does not necessarilyconstitute or imply its endorsement, recommendation, or favoring bythe United States Government or any agency thereof. The views andopinions of authors expressed herein do not necessarily state or reflectthose of the United States Government or any agency thereof.

PB.19 Utilization of Lightweight Materials Made fromCoal Gasification Slags

Vas Choudhry (70402.3 150@compuserve.tom; 408-945-4282)

Steve Hadley (70402.3 150@?,compuserve.tom; 408-945-4282)

Praxis Engineers, Inc.852 North Hillview Drive

Milpitas, CA 95035

Abstract

The integrated gasification combined-cycle (IGCC) coal conversion process has beendemonstrated to be a clean, efficient, and environmentally acceptable method of generatingpower; however, it generates solid waste materials in relatively large quantities. For example,a 400-MW power plant using 4000 tons of 10’%0 ash coal per day may generate over 440 tons/dayof solid waste or slag, consisting of vitrified mineral matter and unburned carbon. The disposalof these wastes represents significant costs, Regulatory trends with respect to solid wastedisposal, landfill development costs, and public concern make utilization of solid wastes a high-priority issue. As coal gasification technologies find increasing commercial applications forpower generation or production of chemical feed stocks, it becomes imperative that slag utilizationmethods be developed, tested, and commercialized in order to offset disposal costs.

Praxis is working on a DOEMETC funded project to demonstrate the technical andeconomic feasibility of making lightweight and ultra-lightweight aggregates from slags left assolid by-products from the coal gasification process. These aggregates are produced by controlledheating of the slags to temperatures ranging between 1600 and 1900”F. Over 10 tons ofexpanded slag lightweight aggregates (SLA) were produced using a direct-fired rotary kiln anda fluidized bed calciner with unit weights varying between 20 and 50 lb/ft3. The slag-basedaggregates are being evaluated at the laboratory scale as substitutes for conventional lightweightaggregates in making lightweight structural concrete, roof tiles, blocks, insulating concrete, anda number of other applications. Based on the laboratory data, large-scale testing will beperformed and the durability of the finished products evaluated. Conventional lightweightaggregates are made from pyroprocessing of expansible shale or clay and sell at $30-40/ton. Thenet production costs of SLA are in the range of $22 to $24/ton. Thus, the technology providesa good opportunity for economic use of gasification slags.

Research sponsored by the U.S. Department of Energy’s Morgantown Energy Technology Center, under contractDE-FC21 -94MC30056 with Praxis Engineers, Inc, 852 North Hillview Drive, Milpitas, CA 95035.

Utilization of Lightweight Materials Madefrom

Coal Gasification Slags

Praxis Engineers, Inc.Milpitas, California 95035

Funding Sources: METC, EPRI, and ICCI

Project Objectives

Developtechnologylightweight

Produce 10

and demonstrate thefor producing slag-basedaggregates (SLA)

tons of SLA Products withdifferent unit weights from two slags

Collect operational and emissions datafrom pilot-scale operations

Laboratory- and commercial-scaleevaluation of SLA with conventionallightweight and ultra-lightweightaggregates (LWA and ULWA)

Project Objectives (contd)

Characterize SLA products forleachabi l i ty and conduc tapplications testing

Evaluate recovered char forrecycle to the gasifier, and foruse as a fuel during slagexpansion or in the boiler

Conduct preliminary economicsof SLA production

Slag, LWA, ULWA, & SLA:Definitions

➤ Slag is a solid residue by-product ofcoal gasification combined-cycleprocess

F Gasification slag is vitrified ashcontaining some unconverted carbon

F Conventional LWA:- Produced by pyroprocessing clays

and shales at 2 100”F- Unit weight is 50 lb/fi3. Used to make lightweight structural

concrete, blocks, and roof tilesMarket price is $20-30/ton

,

Definitions (contd)

F Conventional ULWA:- Produced by pyroprocessing perlite

ores at 2000”F- Unit weight is 4-12 lb/R3- Used for horticultural and insulation

applications- Market price is over $200/ton

F Slag can be expanded under controlledconditions to produce lightweightmaterials, termed slag-based LWA orSLA:- Produced by pyroprocessing at 1600-

1800”F- Unit weight is 12-50 lb/fi3- Blendable with existing raw materials- Can be substituted for all or part of the

ingredients of some LWA and ULWAapplications

MUFFLE BURN TESTS - EXTRUDED MIXTURES

BURN TESTS ALL THREE BLENDS

.,.

50/50, 1900%=1 /5mjn :

1

50/50 MIX-COMPLETE CUP BURN - 1900”F

Specifications

LkdHeigti 3J?

FeedHeigM(Above Gtit#: Zjl

hide IMameta e.sJ

Z?npc?rerhere: +1420%2FneL

_—

Reactor Section Detail

Feed\ , A1#v

1 1 ,,, - ,

H

Act

A Grid Level 11

—Air Disirib&”on

Me

h r- 2tBed TC

Fuel

L-Material flow - -’*.” w;::,.,,.

Gas Flow5“”’” –-”-)3 ‘I=tiI / u

Dired-FirdAir He&r

\l.D. FAN]

I

JFILTERINLETTCIPT

E!!EJ.

*I

/

3’x30’ Rotary Kiln Schematic

CHROMELTHERMOCOUPLES

/ 1 1---1FIRINGHOOD

PT

AIR+

#2 FUELOIL

80

70

- 5 0

40

30

20

10

\I

!

) I I I I I 1 I I I I I i I I I I I I I I [ I I I I I I I I I 1 I I I I I I I [ I I I I I I I I i I I I I

TEMPERATURE (“F)

+1() meshSlag I

A

4 x 20 mesh80/20 pellets

-w

-8 mesh50/50 pellets

4 x 20 mesh50/50 pellets-w/ ph

A

4 x 20 mesh50/50 pellets-no ph

4 x 20 mesh50/50 TVA pellets

7

4I

II

I

t

)I

/II

II

II

II

II

II

oC9

Lou)

iL-C

&m-1g

w’)zwnm

0m

tt

wd

do0

00

00

00

00

0

t-mce

F

=co

m*

m

mv

orrrn-r—/--?

~

“..

c<—.—

—

lull

,.

1 1 c I 3 I 4~:~6 7 0 9 1 0 II 1.? 13 ““” 1.. —— ,;

.B15

. WI

PROMJCT B I NP R O D U C T B I NPRODUCT BINPRODUCT BINPROOUCT B I NBURNCRBURNCRBELT SCALEBELT SCALCAGGRCGATC COOLERCDNC CRUSHERDRYCR (5’ X S5’)DUCT 1 NGDUCTINGDUCT 1 NGDUCT I NC)D I V E R T E R V A L V EDIVCRTCR V A L V ED I V E R T E R VALVED I V E R T E R V A L V ECXTRUDERS L A G B I N +10 T O ~S L A G B I N - S OCLAY B I NFANf ANrAN,FANrANK I L N <9’ X 1 2 0 ’ )P U G M I L LR O T A R Y FEEDERR O T A R Y rf[DCRR O T A R Y fECOERR O T A R Y rEEOCRR O T A R Y fCCOCRR O T A R Y rECDCRR O T A R Y fEZDCRR O T A R Y rEEOCRR O T A R Y SCRtXNSCRUBB[RSCREW CONVCYORC L A Y rECOCRSTACKSTACK

so

. OU2

(30” DIA. X 6 0 ’ )(20’DIA. x 30’)( ? O ’ D I A . X 30’)

c.fB1

mAGBIN

● IO +s0

.Rrl

L. BC5

.Bls

.RF7

.

. . . =.. . ...’,= . . . . . . . _g2.i2FT=.F:..-=. F

.,, . . .

Ws&uld ”””

~ 0“,984——?= .- . . . . . .. .,Ctl ,G– “’ ““!WIS AM Odl 002

,m.?c .% Suol+m>asul \8Jm4 0sS1313d IM Cldl S&z

U/p* .palDl* ● I -1* Owwou aJwl.—

INv-sd 31wJ3zmv 11’01 M Lmsl -1 ——- . . .,b$tmwwsm”-u Wm$w @13X AuJ-u lN3Mdlf103 amdmd

dIlcfllan*Pm-um .—— -——. -

II .*W.als.tils=1 swq!*IUIS,wJ, @l J>c?o / *buol UI -ICI*WINNWfro%AWWIOUIB14

———-— ---..—.—

. . .——.—

/

130”

?~,aS*”PAI”C*”z?-% “

910”Elan.31a”Ila”

-+AO “d &ho ‘Jam -J lAO”

12s”

I

ml

Sno”u

I]H l-lx”

b280” n

L-m “

SIC”

f)NIE

AV13m>”

o93”

os-N18Wss

203”

L

%

1X3”

md”‘T

Lx ‘

?=?

1,s. CD- IRE”

I—. .

T--iF--G212-.=. -. .81l-—lr--l~ c1*I .c1

SLA Products Made at Pilot Scale

Slag/Size/ Direct- Fluidized BedMix Type Fired Kiln Expander

lblfd lblf~

Slag I: +1OM 28-67 24-73Char injection -- 16-26

Slag I: 10x 50M 34-58 --

Slag I: +50M 38 16-58

Extruded80/2050/500/100

Slag I/Clay27-62 --21-42 --18-41 --

Slag I/Clay Granules80/20 4 X 20M .- 30-6080/20 4 X 30M -- 37-4250/50 4 X 20M -- 31-6550/50 -8M -- 43-66

Slag II: +1OM 22-82 --

Slag 11/Clay Granules

50/50 4 X 20M -- 33-63

Production Costs of SLA vs.ULWA ($/Ton)

LWA and

SLA(3)Cost Item Shale/Clay PerliteLw7A(~) ULWA(2)

System Rotary Kiln Vert.Shafl Rotary KilnFurnace

Fuel.011 Natl gas Coal/char

Mining/prep 6.00 40.00 -

Trans~ort 0.50 40.00

Clay binder 1.45

Labor 6.23 12.00 6.25

Fuel 5.09 8.00 1.64

Power 1.37 4.50 1.35

M&S 1.85 3.00 1.48

Other 1.11 2.00 1.10

Overhead 2.24 10.00 -

Depreciate 5.71 4.75 4.28

Interest excluded excluded 6.85

Total 30.10 124.25 24.40Estimated by(1) Fuller Co., (2) Silbrico, (3) Praxis/Fuller

Conclusions: Slag Processing

➤ Slag I was expanded to unit weights of30-50 lb/fi3 and Slag II to 20-50 lb/fi3by means of temperature control.Attempts to lower these firther resultedin fusion which is a function of slagchemistry.

➤ The entire 1/4” x 50M fraction can beprocessed in the kiln as a single feed.

➤ Minus 50M fines must be extrudedprior to kiln processing. Extrudedpellets using 20-50% expansive claybinder yielded product unit weights of27-33 lb/fi3 at 1800 -1900”F.

Conclusions: Char Utilization

F Char can be recovered from slageasily and used as a fuel

F A char product containing 45-54%ash was upgraded successfully to70!% carbon

➤ Char can be utilized as a substitutefor 50% of the fuel in a rotary kilnand 80°/0 of the fuel in a fluidizedbed system

Conclusions: SLA Economics

F Expansion temperature for slag is 300-400 “F lower than that typically requiredfor expansible clays and shales andrepresents significant energy savings

F SLA production costs from a large (440t/d) facili ty were estimated at$24.40/ton using rotary kiln and$21.87/ton using fluidized bed vs.$30. 10/ton for conventional LWA plant

F Preliminary analyses also indicate thatsmall SLA plants can be economicallyattractive if the avoided costs of slagdisposal ($10-$20/ton) are factored in.

Planned Product Evaluation

Commercial-scale testing of

(Phase II)

SLA as asubstitute for LWA and ULWA in thefollowimz amiications:

Structural concrete using 3/4” coarseand 3/8” LWA

Lightweight blocks (2-3 blends)

Insulating concrete (ASTM C 332Group II concrete, 45-90 lb/i33)

Lightweight roof tile aggregate

Loose fill insulation (ASTM C 549)

Horticultural applications