1-step acidic gold bioleaching by the use of iron and sulfur oxidizing and thiocyanate (SCN) generating microorganisms

从低品位硫化金矿石中提金的传统工艺是在低pH值下堆浸矿石，在细菌的帮助下氧化硫化物，然后洗涤固体，最后用含氰化物的溶液浸出堆，以将金浸出成氰化物。该方法具有环境和成本缺点，因为在堆操作中氰化物的应用具有环境后果，并且在硫化物氧化后堆pH是酸性的，并且需要用石灰中和以将pH增加到氰化浸金所需的水平，即pH 9.5至10.5。石灰成本和氰化物使用的环境问题是这种标准工艺的主要挑战。*本文提出在酸性pH条件下一步完成硫化物氧化和金浸出。在这个拟议的过程中，硫化物矿物与通常的细菌氧化，但此外，硫氰酸盐生产细菌在堆中使用，以产生硫氰酸盐作为浸出剂的金浸出在酸性pH值。该过程将减少石灰消耗的工厂（整个过程将在酸性pH值进行），并将消除氰化物的使用。硫氰酸盐的毒性比氰化物低200倍，因此对黄金回收更具吸引力。通过这个项目，将培养一名博士生。

The conventional gold extraction process from low grade sulphide gold ores is to heap leach the ore at low pH to oxidize sulphides with the help of bacteria, and then wash the solids and finally leach the heap with cyanide containing solution to leach gold into cyanide. The process has environmental and cost disadvantages as the cyanide application in the heap operation has environmental consequences, and also the heap pH is acidic after sulphide oxidation and will require neutralization with lime to increase the pH to the required level for gold cyanide leaching, i.e. pH 9.5 to 10.5. The lime cost and environmental issues of cyanide use are the main challenges with this standard process.****Here it is proposed to do both the sulfide oxidation and gold leaching in acidic pH in one step. In this proposed process, sulfide minerals are oxidized with the usual bacteria, but in addition, thiocyanate producing bacteria are used in the heap to produce thiocyanate as the lixiviant for gold leaching in acidic pH. The process will reduce the lime consumption of the plant (the whole process will be carried out at acidic pH) and will eliminate cyanide use. Thiocyanate is 200x less toxic than cyanide thus making it much more attractive for gold recovery. Through this project a PhD student will be trained.