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Abstract
The segregation pattern for dry beneficiation of fine coal (–1.0 + 0.1 mm) in an air table was investigated. The feasibility of cleaning a high ash (~49%) coal to the ash level specified for application in a thermal power plant (34%) was established. The density (ash) distribution pattern on the deck surface at steady state established the progress of segregation under various operating conditions. The operating regimes for a desired product at suitable mass yield were identified. A strategy was developed to process the high ash thermal coal and the flow scheme was established through which around 47% mass yield of the clean coal was obtained at 34% ash level. A second product was generated which was suitable for application in a fluidized bed combustion unit. A completely rejectable tailing was also obtained with 69% ash having a mass yield of 33%. Thus, it was established that high ash coal fines can be treated efficiently by controlled air fluidization over an inclined porous deck. The present study also brought out the features of separation and how segregation progresses over the deck as the material moves towards the discharge end. The effects of important process variables on the separation performance as well as on the segregation pattern were also established.