Reverse flotation of cut-of-grade of Lakhra coal

Abstract

ABSTRACTThe selective mining activities have generated a huge quantity of poor grade coal that is rich in mineral matter and sulfur content and has piled up in whole mining site at Lakhra. This highly oxidized and mineral matter rich coal has been upgraded by reverse floatation. Three process parameters such as pH (7, 8, 9, 10, 11), particle mesh size (60, 100, 150, 200), and % solids (10, 15, 20, 25, 30) in flotation pulp have been investigated with respect to their effect on sulfur and ash reduction. According to results of this study, parameters such as particle size of 100 mesh (150 µm), pH 9 and 20% solids were found to be optimum removing 63.7% of ash and 72.9% of sulfur from coal and coal recovery of 61.3%. Moreover, the heating value of coal also improved from 3924 kcal/kg to 5500 kcal/kg ~ 40.16% enhancement. The recovery of combustibles and gangue at optimum conditions was found to be 60.31% and 39.1% respectively. The clean coal thus obtained containing 12.7% ash, 1.5% sulfur, and 5500 kcal/kg heating value can be used as an energy source for cement manufacturing, in utility boilers, and production of smokeless briquettes for domestic and industrial use.