Water Washing of Fungal-treated Carbonaceous Ores: Effect on Aurocyanide Adsorption by Activated Carbon in CIL Circuit

Ghana Mining Journal Pub Date : 2018-06-28 DOI:10.4314/gm.v18i1.8

R. Amankwah, G. Ofori-Sarpong, Abigail Ewoenam Adzigbli

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引用次数: 2

Abstract

A typical challenge encountered on most gold processing plants during leaching of refractory ores is the reduction in recovery due to the presence of carbonaceous matter which preg-robs dissolved gold. To reduce preg-robbing during cyanidation, carbonaceous matter has to undergo pretreatment to passivate the active surface. The fungus, Phanerochaete chrysosporium has been shown to biotransform carbonaceous matter, thus reducing its ability to preg-rob gold. However, the possible transfer of entrained fungal biomass into Carbon-In-Leach (CIL) circuits has been reported to decrease the activity of activated carbon, and a proposed solution to this was to wash the fungal-treated material thoroughly with water before CIL operation. This paper therefore set out to assess the effect of water-washing on aurocyanide adsorption by activated carbon in CIL following fungal pretreatment of carbonaceous ores. To realise the objective, activated carbon was contacted with cell-free extract of P. chrysosporium under varying conditions of pH and time, after which it was washed with different volumes of water, and its gold-adsorption ability assessed. The results revealed a decrease in the activity of activated carbon as a function of increasing contact time with the cell-free extract. The percentage decrease was higher after treatment in the acidic medium (13%) than the basic medium (9%). After washing the carbon (treated in acidic medium), gold adsorption was found to increase directly with the volume of water used from 64% at 0 mL to 84% at 500 mL and 91% at 1000 mL. Correspondingly, the carbon treated in basic medium recorded 69% at 0 mL to 87% at 500 mL and 93% at 1000 mL. This paper thus concludes that, sufficient water washing should be employed after fungal-biotransformation of refractory ores before CIL operation to decrease the effect of entrained biomass on the adsorption capacity of activated carbon. Keywords: Carbonaceous Gold Ore, Activated Carbon, Carbon-In-Leach, Cell-Free Extracts

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真菌处理炭质矿石的水洗:对活性炭在CIL回路中吸附氰化物的影响

大多数黄金加工厂在浸出难熔矿石时遇到的一个典型挑战是，由于存在含碳物质而使溶解的金浸出而导致回收率降低。为了减少氰化过程中的抢胎现象，必须对含碳物质进行预处理，使活性表面钝化。真菌，黄孢Phanerochaete chrysosporium已被证明可以生物转化碳质物质，从而降低其孕抢金的能力。然而，据报道，携带的真菌生物量可能会转移到碳浸出(CIL)回路中，从而降低活性炭的活性，对此提出的解决方案是在CIL操作之前用水彻底清洗真菌处理过的材料。因此，本文开始评估水洗对炭质矿石真菌预处理后CIL中活性炭吸附氰化物的影响。为了实现这一目标，在不同的pH和时间条件下，将活性炭与无细胞的黄孢假单胞菌提取物接触，然后用不同体积的水洗涤活性炭，并评估其吸附金的能力。结果表明，随着与无细胞提取物接触时间的增加，活性炭的活性降低。在酸性培养基中处理后的百分比下降(13%)高于碱性培养基(9%)。在酸性介质中处理的碳洗涤后，金的吸附性随水体积的增加而直接增加，从0 mL时的64%增加到500 mL时的84%，1000 mL时增加到91%。相应的，在碱性介质中处理的碳在0 mL时为69%，500 mL时为87%，1000 mL时为93%。在CIL操作前，对难处理矿石进行真菌-生物转化后，应进行充分的水洗，以减少夹带的生物质对活性炭吸附能力的影响。关键词:含碳金矿石，活性炭，浸出碳，无细胞萃取物

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Ghana Mining Journal

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