june 3, 2014 beneficiation of lvc coal in india a challenge dr kalyan sen, director central fuel...
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April 10, 2023
Beneficiation of LVC CoalBeneficiation of LVC Coalin Indiain India
A ChallengeA ChallengeDr Kalyan Sen, DirectorDr Kalyan Sen, Director
Central Fuel Research InstituteCentral Fuel Research InstituteDhanbad 828 108Dhanbad 828 108
April 10, 2023
Coal Scenario in IndiaCoal Scenario in India
83.0% 14.0%
3.0%
Prime coking
LVC
MVCHVCSemi-coking
19%
50%
15%
11%6%
Total Coal Reserves 206239.5 mt
Non-coking
Coking
Others
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COKING COAL FOR COKING COAL FOR METALLURGICAL USESMETALLURGICAL USES
REQUIREMENT : 25mt /yr.
IMPORT (1997-’98) : 10.6mt
SHORTFALL :
Depletion of good upper seam coal high cost of underground mining
(1998-99)
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LVC Coal Scenario in IndiaLVC Coal Scenario in India
LowVolatileCoking
50% ofTotal Coking Coal
15,680 mt
Available Resource
AlternativeProposition
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LVC Coal Scenario in IndiaLVC Coal Scenario in India Annual Production (16 -18 mt)
8 to 10 mt from Jharia 6 to 8 mt from East Bokaro
Present Use Power Stations (major consumption) Beehive ovens (minor consumption)
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Mining ConditionMining Condition
LVC coals outcrop near the fringe areas of coalfields
Easy for Opencast production Low overburden : coal ratio Low slope Possibility of high scale mechanization
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WASHABILITY STUDIESWASHABILITY STUDIESWITH LVC COALWITH LVC COAL
Lab. and Pilot plant study at CFRI
Sample : V/VI/VII/VIII Seam coal
of Jharia Coalfield
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Characteristics of LVCCCharacteristics of LVCC
High raw coal ash 35-45%
High Maturity Ro = 1.3
Low volatile matter content 15-16%
High Inertinite content (60-70%)
Poor washability potential
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LVC CoalsLVC Coals
Presently NLW grade
Unwashable !‘Formidable’ to wash !
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Liberation Potential of GOCP CoalLiberation Potential of GOCP Coal
0102030405060708090
100
Yield %
0 10 20 30
Ash%
Raw coal X 75mm & deshaledDeshaled coal X 13mm
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Liberation of coal/ mineral
particles by progressive size
reduction is insignificant
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‘‘Difficult - to - wash’Difficult - to - wash’
Due to
Typical Geological formation Intergrown Mineral matter High NGM at desired d50
Poor plant performance
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Theo. Yield of products from GOCP coalTheo. Yield of products from GOCP coal
0102030405060708090
1000 10 20 30 40 50 60 70
Ash,%
Yie
ld,%
2- product separation
Cleans ~30% of ash 18%
Rest ash 45% ( sale value ? )
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Theo. Yield of products from GOCP coalTheo. Yield of products from GOCP coal
0102030405060708090
1000 10 20 30 40 50 60 70
Ash,%
Yie
ld,%
Cleans ~30% Ash 18%
3- product separation
Rejects ~20% Ash 60%
Middling 50% Ash ~41%
( fate? )
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CFRI’s ConceptCFRI’s Concept
Sp.Gravity based Washability Model
Limiting Characteristics Ash
Multi-stage washing
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1.25 1.35 1.45 1.55 1.65 1.75 1.85 1.95 2.050
10
20
30
40
50
0
10
20
30
40
50
60
70
80
Char. Ash
Fra
ctio
nal
Yie
ld
Mid Sp. gravity
Ch
ar. Ash
%Density-wise mass distribution of GOCP CoalDensity-wise mass distribution of GOCP Coal
Claens RejectsFoundry
CoalPower Coal
4- product separation
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A Typical FlowsheetA Typical Flowsheet
Cleans Sinks Cleans Sinks Conc.. Tailings
Screened 13/6 mm & 0.5mm
R..O.M Coal X75mm
Cleans A Rejects Effluents
Precleans
75-13/6mm 13/6-0.5 <0.5mmRewash in
HM Bath/Cyclone Flotation
Total Cleans Foundry Fuel
Power Coal20-28%(a 60-65%)
50% (a21-23%)
20-28%(a34-37%)
25-28%(a17-18%) 20-23%(a27-29%)
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Technological SolutionTechnological Solution
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Issuies for AttentionIssuies for Attention
Economics of Clean coal
Washing Circuit
Quality of Product
Effect of Raw coal ash on yield
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PricePrice
ofof
Clean coalClean coal
at 17 - 18 % ash ?at 17 - 18 % ash ?
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Beneficiation in existing washeries
2-product circuit
About 70-75% with 40-45% ash with no
market outlet
Cost of clean coal is approximately 5 times that of raw coal
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Beneficiation in existing washeries
3-product circuit
LVCC requires disposal of 20% as reject
50% middling with 41% ash (outlet ?)
Cost of clean coal is 4 times that of raw coal
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4-Product Circuit4-Product Circuit
Cleans (25-30%), 17-18% ash
Foundry cleans (20-25%), 28% ash
Middlings (20-22%), 34% ash
Rejects (28-30%), 60-65% ash
Cost of clean coal is about 3 times that of Raw coal price
April 10, 2023
April 10, 2023
CircuitCircuitforfor
1 mt washery1 mt washery
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April 10, 2023
Purpose ofHM Drum
&HM Cyclone
in the Second Stage
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1.3 1.4 1.5 1.6 1.7 1.8 1.9
Relative density
0
10
20
30
40
50
60
70
Ch
ara
cte
ristic
Ash
%
Char. Ash 26-28%
Coarser coal
Smaller coal
Cut Densities for HMB & HMC
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QualityQualityofof
Clean coalClean coal
April 10, 2023
Washed Coal AnalysisPetrographic Analysis
Mean Ro % 1.27
Vitrinite % 53.2
Semi Vitrinite % 4.8
Exinite % 0.3
Inertinite % 31.5
Mineral Matter % 10.2
April 10, 2023
Washed Coal Analysis
Chemical Analysis
Moisture % 0.9
Ash % 18.3
V. M. (%dmf) 21.0
S.I. 5.0
Max Fl. (ddpm) 150.0
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Washed Coal
Coke Property
Porosity % 48.5
CRI 12.6
CSR 72.9
M40 82.6
M10 9.8
April 10, 2023
Effect ofEffect of
Change in Change in
Raw Coal AshRaw Coal Ash
onon
Clean Coal Yield Clean Coal Yield
April 10, 2023
Predicted cleans from Raw coals Predicted cleans from Raw coals of varying ash valuesof varying ash values
Raw coal Precleans Foundry Fuel Cleans
ash,% wt ash% wt ash% wt ash%
34.0 47.9 21.8 19.0 28.3 28.9 17.5
35.0 45.0 21.6 17.5 28.4 27.5 17.3
36.0 42.8 21.5 15.4 28.5 27.5 17.6
37.0 42.0 21.6 16.2 28.5 26.8 17.6
April 10, 2023
Predicted Cleans Vs. Raw coal ashPredicted Cleans Vs. Raw coal ash
32 34 36 38 40
Raw coal ash,%
20
25
30
35
40
Yie
ld a
t 17.
5% a
sh
ooo o
Y = 60.3 - 0.9 ash
April 10, 2023
Thank You