Application of air table technology for cleaning Indian coals

Beneficiation of thermal coal in India is a relatively new development. For the year 2006, India produced 380 million tonnes of thermal coal, of which only 17 million tonnes were beneficiated coals. One potentially attractive method for upgrading India's coal feed stocks is the air table dry deshaling technology. Dry deshaling offers significant advantages over wet cleaning operations, including reduced surface moisture, enhanced heating value, elimination of processing water and waste slurries, and reduced transportation of large amounts of ash-forming minerals. To evaluate this potential, a pilot-scale air table deshaling unit was tested at three locations in India for the specific purpose of upgrading thermal coals. The field testing confirmed that the separation performance for Indian coals is similar to that which has been achieved at sites in the United States for material in the 50 x 6 mm size range. The data indicate that material with 80% ash and higher can be rejected by the dry deshaler unit with a combustible recovery of more than 90%. A very good separation was also obtained in the laboratory for the dry deshaling of a fine coal sample (minus 6 mm) obtained from one of the test sites in India.