Central Fuel Research Institute Dhanbad 828 108 presents

1
Central Fuel Research Institute Dhanbad 828
108presents
Beneficiation of difficult-to-wash Low Volatile
Coals of Jharia and Bokaro Coalfields
by
Kalyan Sen and Rahul Das Gupta
2
Coal in India
Total Coal Reserve 206 billion tonnes
Distribution

• Non Coking (Gondowana) 83
• Coking (Gondowana) 14
• Others 3

3
Coking Coal Scenario
4
Characteristics of LVCC

• High raw coal ash 37-40
• Low volatile matter content 15-16
• Poor washability potential
• High Maturity Ro 1.3
• High Reserve 15,680 mt

5
Mining Condition

• LVC coals outcrop near the fringe areas of
  coalfields
• Easy for Opencast production
• Low overburden coal ratio (upto 3)
• Low slope (1 15)
• Possibility of high scale mechanization

6
Washability Potential

• Very poor washability due to typical geological
  formation
• Liberation of coal / mineral particles by
  progressive size reduction is insignificant

7
Mayers Curve
8
Present scenario

• Annual Production of LVCC (16 -18 mt)
• 8 to 10 mt from Jharia
• 6 to 8 mt from East Bokaro
• Use of NLW coals
• Power Stations (major consumption)
• Beehive ovens (minor consumption)

9
Beneficiation in existing washeries
Existing Washeries

• 2-product circuit
• About 70-75 with 40-45 ash with no market
  outlet
• Cost of cleans is more than 5 times that of raw
  coal
• 3-product circuit
• 4-product circuit

10
Beneficiation in existing washeries
Existing Washeries

• 3-product circuit
• Low reject disposal capacity of old deshaling
  Jigs
• LVCC requires about 20 disposal
• Congenial defects in the cyclones circuits
• 60 middlings with 45 ash (Fate ?)
• 20 rejects - 50 with 41 ash (outlet ?)
• Cost of cleans is 4 times that of raw coal ?

11
Pilot Scale Study at CFRI

• 1200t of V-VI-VII-VIII seam coal was beneficiated
  in the Pilot Plant
• Cleans at 17-18 ash was carbonized at CFRI
  RDCIS
• Tested at Bokaro test ovens
• Highly encouraging results

12
Washed Coal Analysis

• Petrographic Analysis
• Mean Ro 1.27
• Vitrinite 53.2
• Semi Vitrinite 4.8
• Exinite 0.3
• Inertinite 31.5
• Mineral Matter 10.2

13
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

14
Washed Coal
Coke Property Porosity 48.5 CRI 12.6 CS
R 72.9 M40 82.6 M10 9.8
15
Proposed Scheme
4-Product Washing Multi Stage Concept 1st Stage
3-product Jig 2nd Stage HM Flotation
16
1st Stage Products

• Rejects 28-30 wt, 60-65 ash
• Middlings 20-22 wt, lt34 ash
• Pre-cleans (about 50), 22-24 ash

17
2nd Stage Product

• Cleans 25-30 wt, 18 ash
• Foundry cleans 20-25 wt, 28 ash
• Cost of cleans about 3 times that of Raw coal

18
Multi-stage Concept
19
Comparative Cost of Cleans

• 2-product 5
• 3-product 4
• 4-product 3

20
Thank You