Optimization of an Iron Ore Washing Plant

Abstract

The sustainable viability of a mineral enterprise depends on improving the concentrate quality, generating readily salable by-products, improving recovery, throughput, and reduction of unit cost rate and maximize the unit income rate and thereby unit profit rate. Closing down of iron ore mines due to environmental constraints spurred the captive iron ore washing plants to workon a custom plant mode and also recover the values from their slimy tails. This paper enumerates the difficulties faced by a captive iron ore fine washing plant [treating iron ore fines assaying Fe∼58% yielding sands assaying Fe>60%] due to raw material change yielding unsalable sands and discuss the importance of process plant audit for improving the mineral processing plant performance. Based on the base line study, laboratory tests on typical samples followed by short term modifications, retrofitting of downstream slime concentrating wet high intensity magnetic separators and dewatering of products could produce readily salable sinter grade [Fe>60%] and pellet grade[Fe>62.5%] with an overall increase of concentrate yield by 11.5%. Even the previous wash plant tails [which assayed Fe > 45%] may be reprocessed in the retrofitted slime processing VPWHIMS plant. The final tails assayed 38.60% Fe at weight % yield of 28.5. Efforts are on for utilizing the above tails in bricks- tiles manufacture. Also, R&D efforts to concentrate Fe values from above 38.60% Fe tails by Magnetizing roast followed by magnetic separations in bench scale has given encouraging results. Thus auditing not only improved the quality, quantity and rate of production of concentrate but mitigated the problem of tailing disposal. The investments were repaid within a year of operation and unit operating costs reduced by 20% with reference to base line data.