Process Alternatives to Recover High-Grade Iron Ore Concentrate from the Thickener Underflow Slimes of the Sishen Beneficiation Plant

摘要

Kumba Iron Ore's Sishen Mine is one of the world's largest iron ore mining operations situated in the Northern Cape, South Africa. It produces 29 million tonnes of iron ore products per annum using a Dense Medium Separation (DMS) beneficiation process. Kumba is currently commissioning the Sishen Expansion Project (SEP) which will produce a further 13Mtpa product through a jigging beneficiation process. The products from the Sishen Mine are highly sought after and consumed by domestic and various European and Asian customers. During beneficiation iron ore slimes are generated and discarded as waste material to the slimes dams. A study was initiated in 2005 to investigate processes to beneficiate these slimes to saleable products - prompted by the current high demand for iron ore products and the high grade in the Sishen slimes thickener underflow of approximately 54 percent Fe. Initial laboratory scale test work indicated that a 66.5 percent Fe iron ore concentrate could be produced from the Sishen slimes thickener underflow through a process of classification, two stage wet high intensity magnetic separation (WHIMS) and five stage flotation. This process, however, did not produce the desired results during pilot plant testing and numerous alternative process routes were investigated. The process that did achieve the desired product grade of 66.5 percent Fe at economically feasible product yields consisted of two stage WHIMS using SLON magnetic separators. Results achieved indicate that the thickener underflow slimes can be upgraded from 54 percent Fe to 66.5 percent Fe at a product yield of ca. 40 percent . Product yield could be increased through the further beneficiation of the SLON tails. The Sishen slimes thickener underflow production rate is ca. 3Mtpa - resulting in a potential concentrate production of ca. 1.2Mtpa. The slimes concentrate will be fed to a pelletising plant that will produce 66 percent Fe pellets destined for domestic and or export markets.