SBIR Phase II: Cyanide-Free Biocatalyzed Leaching of Gold and Silver Ore

9529722亨特金矿和银矿往往位于非常容易受到采矿和金属回收活动污染的原始环境中。虽然生物技术已经被开发出来从难处理的矿石中提取贵金属，但氰化仍然是提取金银价值的首选方法。这个小型企业创新研究第二阶段项目将继续开发一种从生物氧化矿石中提取金银的生物湿法冶金新工艺。该项目调查了二硫化物浸出液作为传统氰化工艺的一种有效、但更环保、成本更低的替代方法的使用。然而，近年来，将环境成本添加到开采金银的总成本中，刺激了人们寻找更环保的选择。建议的二硫化物浸出方法利用了硫酸盐还原菌能够(1)产生溶解的硫化物作为贵金属的络合剂，以及(2)消耗络合(厌氧腐蚀)反应产生的氢气的事实。在第二阶段，将设计、建造和运行实验室原型；然后将其性能与传统的氰化工艺进行比较。原型将包括生物氧化、黄金提取和黄金回收的子系统。建议改变金银提取的基本技术，从源头上减少与采矿有关的污染。建议的工艺可用于从贵金属(金、银和铂族金属)的矿石和金属废料中浸出贵金属，这是一个全球数十亿美元的市场。如果第一阶段的结果得到证实，二硫化物浸出可以降低化学试剂的成本。拟议的生物湿法冶金工艺可以提供一种既有利可图又相对无污染的金银回收方法。

9529722 Hunter Gold and silver mines are often located in pristine environments that are highly susceptible to pollution by mining and metals recovery activities. While biotechnologies have been developed for freeing precious metals from refractory ores, cyanidation is still the process of choice for extracting gold and silver values. This Small Business Innovation Research Phase II project will continue the development of a novel biohydrometallurgical process for extracting gold and silver from bio-oxidized ore. The project investigates the use of a bisulfide leaching solution as an effective, but more environmentally friendly and less costly, alternative to the conventional cyanidation process. However, in recent years, the addition of the environmental costs to the total cost of mining gold and silver has stimulated a search for options that are more environmentally acceptable. The proposed bisulfide leaching approach takes advantage of the fact that sulfate-reducing bacteria are capable of both (1) producing dissolved sulfides which act as a complexing agent for precious metals and (2) consuming hydrogen gas generated by the complexation (anaerobic corrosion) reaction. During Phase II, a laboratory prototype will be designed, constructed, and operated; its performance will then be compared to that of the conventional cyanidation process. The prototype will include subsystems for bio-oxidation, gold extraction, and gold recovery. A change in the basic technology of gold and silver extraction is proposed that will reduce mining-related pollution at its source. The proposed process can be applied in leaching precious metals (gold, silver and platinum group metals) from their ores and from metal scrap, which is a multibillion market worldwide. If Phase I results are borne out, bisulfide leaching could reduce chemical reagent costs. The proposed biohydrometallurgical process could provide a means of gold and silver recovery that is both profitable and relatively nonpolluting.