West Bokaro meets 50% of the clean coal and 100% of the middlings
requirement of Tata Steel. Clean coal and middlings are products of benefication of raw
coal in dense media cyclones (-13 +0.5 mm) and in forth floatation (below 0.5 mm). The
demand in the Jamshedpur Works for supply of clean coal has been increasing continiously.
To meet this demand at the desired cost, a team from Coal Benefication Stream 1 comprising
Quarry AB and Washery 2, came up with the ingenious idea of washing weathred coal.
Weathred coal is normally unfit for processing because of its poor floatibility. Another
problem at West Bokaro is that there are no easy means of transporting waethred coal
available in the quarry to the despatch point. The WB Team took this as a challenge and started working
towards winning clean coal from weathred coal. They were aware that the risk were high -
any slight error in judgement would have far reaching consequences.The Team made a detailed plan according to which, the portion of fines reporting to the floatation circuit was minimised by adjusting the gap in the crusher and by changing the aperture of the screen panels. Higher yeild from the deshaling plant and continious operation of the thickner underflow to transport the coal to the tailings ponds rather tahn accumulating it in the thickner were also ensured. The first trial was conducted on 7th July, 2001and 4200 tonnes of weathred coal was processed. 30% clean coal was obtained. The Team's confidence was boosted. In the next trial, weathred coal was processed for fourteen continious shifts and the logistics were estbalished beyond doubt. Processing of weathered coal to the extent of 0.1 million tonnes per annum, is now a part and parcel of operation of CB Stream 1 and Quarry AB. |
