Selective drop breakage studies: a precursor for dry deshaling of Indian non-coking coals

摘要

The coal seams in India are mostly inter-banded, containing stone and hard shales, since such bands cannot be separated during the mining operations; these are mixed with the coal, thereby increasing the ash per cent of the run-of-mine (ROM) coal. In majority of the coalfields, it was found that the nature/ character of the coal and stone is such that the stone is harder than the coal. Hence, it may be possible to remove the hard stone by incorporating a rotary breaker at the pithead or coal handling plant. However, before installing a rotary breaker, it is very much essential to understand the breakage characteristics of the coal and stone.The present investigation includes selective drop breakage tests of coals and stones from variable heights. The differential breakage patterns of this material have been quantified in terms of Selective Crushing Index and its dependence on number of drops and heights. Attempts have been made to find a breakage constant with the assumption of drop breakage as a first-order process dominated by volume breakage. Results of the selective drop breakage tests on coal and stone from non-coking coalfields showed that there is a good potential of installing a rotary breaker at the pithead.