Study of washability characteristics of coals from Seam-IX of Jamadoba Colliery of the Jharia basin, India

Abstract

The present paper entails the results of investigations carried out on the coals of Seam-IX from Jamadoba colliery, Jharia basin to know their washability characteristics. The coal samples have been subjected to liberation study, sink-float tests, froth-floatation study and alternative process to obtain maximum clean coal fractions. To understand the nature of mineral matter occurrence, petro-chemical characteristics have also been studied. It is observed that -3 mm top-size fraction has a relatively better potentiality to produce clean coal compared to any other top-size fractions (-20, -15 and -10 mm). However, the crushing of ROM coal to fine size is more power consuming and will also generate more fines (-0.5 mm). This would require modification in the washing practices. This would eventually increase the cost of coal washing. The coal particles free from any mineral contamination is seen maximum (14.28%) in -3 mm top-size fraction and also the dispersed mineral matter is less in this (-3 mm) top-size fraction and the beneficiation is relatively easy. The optimum result of floatation is achieved at high dose of collector and medium dose of frother. Through petrographic study a substantial decrease in the mineral matter content is noticed from 29.2% in the raw coal sample to 8.2% in the washed coal. Similarly a concomitant fall in the ash yield was also recorded from 38.48% in the raw coal to 15.27% in the washed coal.