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

April 10, 2023

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)

April 10, 2023

LVC Coal Scenario in IndiaLVC Coal Scenario in India

LowVolatileCoking

50% ofTotal Coking Coal

15,680 mt

Available Resource

AlternativeProposition

April 10, 2023

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)

April 10, 2023

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

April 10, 2023

WASHABILITY STUDIESWASHABILITY STUDIESWITH LVC COALWITH LVC COAL

Lab. and Pilot plant study at CFRI

Sample : V/VI/VII/VIII Seam coal

of Jharia Coalfield

April 10, 2023

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

April 10, 2023

LVC CoalsLVC Coals

Presently NLW grade

Unwashable !‘Formidable’ to wash !

April 10, 2023

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

April 10, 2023

Liberation of coal/ mineral

particles by progressive size

reduction is insignificant

April 10, 2023

‘‘Difficult - to - wash’Difficult - to - wash’

Due to

Typical Geological formation Intergrown Mineral matter High NGM at desired d50

Poor plant performance

April 10, 2023

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 ? )

April 10, 2023

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? )

April 10, 2023

CFRI’s ConceptCFRI’s Concept

Sp.Gravity based Washability Model

Limiting Characteristics Ash

Multi-stage washing

April 10, 2023

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

April 10, 2023

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%)

April 10, 2023

Technological SolutionTechnological Solution

April 10, 2023

Issuies for AttentionIssuies for Attention

Economics of Clean coal

Washing Circuit

Quality of Product

Effect of Raw coal ash on yield

April 10, 2023

PricePrice

ofof

Clean coalClean coal

at 17 - 18 % ash ?at 17 - 18 % ash ?

April 10, 2023

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

April 10, 2023

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

April 10, 2023

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

April 10, 2023

April 10, 2023

Purpose ofHM Drum

&HM Cyclone

in the Second Stage

April 10, 2023

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

April 10, 2023

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

April 10, 2023

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