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African Metals Corporation (“AFR”) reported that the Company has successfully completed trial processing of a bulk sample of the historic Luisha South stockpile.
Approximately 200 tonnes of bulk sample grading approximately 2% copper and 0.3% cobalt has been excavated and trucked to a generator powered, modular concentration plant including a DMS (Dense Media Separator) plant and gravity spirals. The 200 tonne material produced a DMS concentrate grading approximately 32% copper, 1.2% cobalt; fines concentrate from spirals graded approximately 28% copper and 1.6% cobalt. The results highlight the economic potential of processing the stockpile material using gravity based separation process technology. The bulk processing results will be used in conjunction with metallurgical test results from METS-SGS in Perth, and a maiden resource estimation which is expected in May, to produce a feasibility study and cash flow model. AFR aims to commence full time concentrate production by end Q3 2011, if the study and cash flow modeling produce favorable scenarios. Luisha South Project Stockpile RC Drilling In October 2010, Magnum Drilling Sprl completed a 42 hole, Reverse Circulation (RC) drilling program on top of the Luisha South stockpile. Based on the positive assay results from the RC drilling program, and the observation that the mineralization is of an oxide nature (malachite and heterogenite), AFR has engaged METS and SGS in Perth, Australia, to conduct metallurgical beneficiation test work aimed at producing a higher grade concentrate amenable to conventional hydrometallurgical leaching. Test work on ore characteristics and heavy media separation qualities has commenced, with beneficiation results expected late May. With the goal of commencing production of an oxide concentrate by the end of Q3, 2011, AFR took an opportunity to run a bulk ore sample through a nearby DMS Plant and spirals. The results of the bulk sample test run were to be used in conjunction with the metallurgical beneficiation test work to optimize copper and cobalt recovery. An initial composite sample was selected to be processed through the DMS plant. The composite sample represented coarse Reverse Circulation (RC) drill chips collected from the stockpile drilling in 2010; the chips came from holes drilled across the stockpile. Approximately 300kg of composite drill material grading on average 0.3% copper and 0.3% cobalt, was transported some 40km to a generator powered, modular DMS (Dense Media Separator) plant and spirals near Likasi for processing. The DMS plant usually operated at an average through put of 50 tonnes of ore per hour, with the spirals processing fines at a throughput rate of 60 tonnes of ore per hour. The plant was simple, and consisted of a Primary Crushing Circuit (-150mm static grizzly screen, jaw crusher, conveyor system, scrubber, -1.6mm double deck sizing screen); Spiral Plant (processing -1.6mm fines); and DMS Plant (processing -27mm to +1.6mm material). Approximately four x 1kg samples were collected from four stages during the DMS plant test run. The samples were dispatched to SGS laboratories in Kalulushi, Zambia, where they were analyzed for copper and cobalt. The DMS plant produced a concentrate grading 15.1% Cu, 0.5% Co. The Spirals concentrate of fine grained material produced a concentrate grading 4.7% Cu, 0.2% Co. The results indicated that the DMS plant successfully produced a higher grade concentrate. The DMS process plant operations’ team however considered the performance of the DMS plant during the processing of the 300kg composite drill material to have been below par; the plant and spirals struggled with the fine-grained nature of the composite RC hammer sample, and the plant may have introduced contamination issues. As a result the company decided to run another trial by processing a 200 tonne bulk tonnage stockpile sample. More information, click here |
