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Coal Scenario in India

Beneficiation of LVC Coal in India A Challenge Dr Kalyan Sen, Director Central Fuel Research Institute Dhanbad 828 108. Coal Scenario in India. Total Coal Reserves 206239.5 mt. Others. 6%. Semi-coking. 11%. HVC. 3.0%. 15%. MVC. 14.0%. 83.0%. 50%. LVC. Coking. Non- coking. 19%.

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Coal Scenario in India

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  1. Beneficiation of LVC Coalin IndiaA ChallengeDr Kalyan Sen, DirectorCentral Fuel Research InstituteDhanbad 828 108

  2. Coal Scenario in India Total Coal Reserves 206239.5 mt Others 6% Semi-coking 11% HVC 3.0% 15% MVC 14.0% 83.0% 50% LVC Coking Non- coking 19% Prime coking

  3. COKING COAL FOR METALLURGICAL USES REQUIREMENT :25mt /yr. (1998-99) SHORTFALL : • Depletion of good upper seam coal • high cost of underground mining IMPORT (1997-’98) :10.6mt

  4. LVC Coal Scenario in India Available Resource 15,680 mt Low Volatile Coking Alternative Proposition 50% of Total Coking Coal

  5. LVC 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)

  6. Mining 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

  7. WASHABILITY STUDIESWITH LVC COAL Lab. and Pilot plant study at CFRI Sample :V/VI/VII/VIII Seam coal of Jharia Coalfield

  8. Characteristics 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

  9. LVC Coals Presently NLW grade Unwashable ! ‘Formidable’ to wash !

  10. Liberation Potential of GOCP Coal Raw coal X 75mm & deshaled Deshaled coal X 13mm

  11. Liberation of coal/ mineral particles by progressive size reduction is insignificant

  12. ‘Difficult - to - wash’ Due to • Typical Geological formation • Intergrown Mineral matter • High NGM at desired d50 • Poor plant performance

  13. 0 10 20 30 40 Yield,% 50 60 70 80 90 100 0 10 20 30 40 50 60 70 Ash,% Theo. Yield of products from GOCP coal 2- product separation Cleans ~30% of ash 18% Rest ash 45% ( sale value ? )

  14. Theo. Yield of products from GOCP coal 0 10 20 30 40 Yield,% 50 60 70 80 90 100 0 10 20 30 40 50 60 70 Ash,% 3- product separation Cleans ~30% Ash 18% Ash 60% Rejects ~20% Middling 50% Ash ~41% ( fate? )

  15. CFRI’s Concept • Sp.Gravity based Washability Model • Limiting Characteristics Ash • Multi-stage washing

  16. Density-wise mass distribution of GOCP Coal 50 80 70 40 Char. Ash 60 50 30 40 Char. Ash% Fractional Yield 20 30 20 10 10 0 0 1.25 1.35 1.45 1.55 1.65 1.75 1.85 1.95 2.05 Mid Sp. gravity 4- product separation Power Coal Foundry Coal Claens Rejects

  17. A Typical Flowsheet R..O.M Coal X75mm Cleans A RejectsEffluents 20-28%(a 60-65%) Power Coal 20-28%(a34-37%) Precleans Screened 13/6 mm & 0.5mm 50% (a21-23%) 75-13/6mm 13/6-0.5 <0.5mm Rewash in HM Bath/Cyclone Flotation Cleans Sinks Cleans Sinks Conc.. Tailings Total Cleans Foundry Fuel 20-23%(a27-29%) 25-28%(a17-18%)

  18. Technological Solution

  19. Issuies for Attention • Economics of Clean coal • Washing Circuit • Quality of Product • Effect of Raw coal ash on yield

  20. PriceofClean coalat 17 - 18 % ash ?

  21. 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

  22. 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

  23. 4-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

  24. Circuitfor1 mt washery

  25. Purpose ofHM Drum&HM Cyclonein the Second Stage

  26. 70 60 50 Coarser coal 40 Characteristic Ash% Char. Ash 26-28% 30 20 10 Smaller coal 0 1.3 1.4 1.5 1.6 1.7 1.8 1.9 Relative density Cut Densities for HMB & HMC

  27. QualityofClean coal

  28. 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

  29. 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

  30. Washed Coal Coke Property Porosity % 48.5 CRI 12.6 CSR 72.9 M40 82.6 M10 9.8

  31. Effect ofChange in Raw Coal AshonClean Coal Yield

  32. Predicted cleans from Raw coals of varying ash values

  33. o o o o Predicted Cleans Vs. Raw coal ash 40 Y = 60.3 - 0.9 ash 35 30 Yield at 17.5% ash 25 20 32 34 36 38 40 Raw coal ash,%

  34. Thank You

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