Sakhre, D.K. (2018) Coal Winnowing: An Innovative Technique for Dry Coal Beneficiation. CPSI Journal , 10 (28). pp. 3-13.

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Thermal Power plants in India burn high ash content coal of 40-60 ash % due to the paucity of low ash coal. Combustion of high ash coals creates a lot of environmental issues like atmospheric pollution, generation of high quantities of fly/bottom ash, water and soil pollution. The common practice for reduction of mineral matter and undesirable pollutants in coal is by wet washing or cleaning. The disadvantages of wet coal cleaning are high water requirement, increase in moisture content of washed coal thereby decrease in heat value, chemical breakdown of coaly material, physical degradation & generation of excessive fines, disposal of slurry water in addition to high capital investment, high processing cost and cumbersome handling. A new dry coal beneficiation system namely "COAL WINNOWING SYSTEM" has been designed & developed. Various coals from Wardha Valley Coalfields of WCL had been experimented in Coal winnowing system. Studies on Coal of size fractions; 50-25 mm, 25-13 mm, 13-6 mm were conducted. One experiment conducted with size fractions of 25-13 mm WCL -Marki Mangli mine coal shows overall ash percentage reduction from 47.4% to 43.1% with cleans yield of 79.5%. The parameters like air velocity, horizontal distribution of particles and handling of higher sized coal, 100-50 mm was optimized. Studies on ROM coal from New Sasti Mines, Wardha Valley Coalfield, Maharashtra on size fraction of 100-75 mm shows overall ash percentage reduction from 55.8% to 37.0% with cleans yield of 48.17%.Winnowing Index is calculated and Tromp curve has been drawn for different size fractions of coal. The probable error (Ep) values for different size fractions are between 0.065 to 0.155 which seems better than the Allair Jig which has Ep value 0.18 during bench scale test in the laboratory. These studies show that Coal winnowing technique can be effectively applied to physically separate the coal & shale/stone particles. The developed technique can be easily applied to dry coal cleaning of non-coking coals for thermal power plant use and will be more useful in as the coal will have low moisture, no chemical breakdown, no physical degradation as well as low capital investment, low processing cost and easy handling.

Item Type: Article
Uncontrolled Keywords: Coal washing, Dry coal beneficiation, Coal winnowing, Non-coking coal
Subjects: Fuel Scinece
Depositing User: Mr. B. R. Panduranga
Date Deposited: 26 Jul 2018 10:47
Last Modified: 26 Jul 2018 10:47

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