SBIR Phase II: An Economic, Sustainable, Green, Gold Isolation Process

这个小企业创新研究第二阶段项目的更广泛的影响/商业潜力是通过提高工艺经济性和减少采矿作业对环境的影响来改变黄金开采方式的潜力。目前的黄金分离方法涉及消耗大量的氰化钠，其中氰化物包含在大型尾矿坝中，构成环境威胁，如有记录的违规行为所示。在美国，由于技术限制和环境问题，有些金矿尚未开采。该项目正在开发的技术将提高现有矿山的盈利能力，因为只需对工厂设计进行微小修改即可使用。这也将带来新的就业机会。另一个机会是从铜尾矿坝中提取黄金。拟议中的技术将有可能使这些网站的清理有利可图，并可在全球范围内应用。从长远来看，第三世界国家可以采用这种工艺，因为这些国家仍然依赖汞，汞不仅污染环境，而且污染食物链。该第二阶段研究项目的目标是（i）扩大使用堆浸和桶浸工艺提取黄金的规模，（ii）优化天然产物α-环糊精存在下Au（III）的结晶，和（iii）分离金。对于堆浸，建议在400公吨水平下操作，浓缩金盐并使金-环糊精络合物结晶。扩大规模将需要在设计工艺时利用现有设备（最初为氰化钠工艺建造的设备），并引进新的化学品。对于桶浸，将建造一个小型试验系统，以接受破碎的矿石作为进料，并将通过结晶过程提取所得的含金提取物。浸出剂、传质、动力学和材料消耗的优化工作将继续进行。 一旦获得监管机构对瓮浸法的批准，就可以在全球范围内现场应用，以证明该工艺的环境和经济效益。这项技术有可能大大提高现有和新的采矿作业的环境可持续性。

The broader impact/commercial potential of this Small Business Innovation Research Phase II project is the potential to change the way gold mining is carried out by improving the process economics and reducing the environmental impact of mining operations. Current gold isolation methods involve the consumption of vast quantities of sodium cyanide, where cyanide is contained in large tailing dams, posing an environmental threat as exemplified by documented breaches. In the United States there are gold deposits which have not been exploited because of technology limitations and environmental concerns. The technology being developed in this project will improve the profitability of existing mines, as it can be employed with only minor changes in plant design. It will also but will also lead to new jobs. Another opportunity is to extract gold from copper tailings dams. The proposed technology will potentially make cleanup of these sites profitable and can be applied worldwide. In the longer term, the process could be adopted in third world countries which still rely on mercury which pollutes, not only the environment, but also the food chain.The objectives of this Phase II research project are to (i) scale up the extraction of gold using both the heap and vat leach processes, (ii) optimize the crystallization of Au(III) in the presence of the natural product á-cyclodextrin, and (iii) isolate the gold. For heap leaching, it is proposed to operate at the 400-MT level, concentrate the gold salt and crystallize the gold-cyclodextrin complex. Scale-up will require designing the process to utilize existing equipment (built originally for the sodium cyanide process) and introducing new chemicals. For vat leaching, a small pilot system will be built to accept crushed ore as the feed, and the resulting gold-containing extract will be taken through the crystallization process. Optimization of the leaching agent, mass transfer, kinetics and materials consumption will be ongoing. Regulatory approval for vat leaching, once secured, can be applied on-site globally to demonstrate the environmental and economic benefits of the process. This technology has the potential to significantly make existing and new mining operations more environmentally sustainable.