Soluble Catalysts for Copper Recovery from Low Grade Primary Copper Sulfide Ores

世界上大约80%的铜来自硫化铜矿黄铜矿CuFeS2。 典型地，黄铜矿矿石被浓缩并且随后被熔炼以获得高纯度的铜。 然而，这些原生铜矿石的品位一直在稳步下降，这使得这条路线对于当今许多低品位矿石来说不太经济。 处理低品位铜矿石的一种潜在的低成本替代方法是堆浸。 然而，众所周知，黄铜矿由于矿物钝化而难以浸出，因此堆浸生物浸出的商业应用迄今为止仅限于次生硫化铜（辉铜矿，Cu2S）矿石。 低品位黄铜矿矿石的堆浸（结合溶剂萃取和电解，或SXEW）多年来一直是湿法冶金的“圣杯”，几种方法已经显示出一定的前景，包括在热堆中使用极端嗜热微生物，其中黄铁矿首先氧化产生热量，以及使用氯化物作为催化剂。然而，热堆是不可靠的，难以控制，氯化物具有极强的腐蚀性。UBC最近的工作表明，用某些可溶性物质催化黄铜矿的浸出是可能的。对黄铜矿电极的电化学测试表明，少量的专有（尽管便宜且容易获得）可溶性有机化合物（其将被称为MFD）使电极去钝化。 柱浸和槽浸实验的初步结果表明，MFD是铁浸出的强催化剂。 添加MFD可防止钝化，显著提高浸出率。 此外，已经停止浸出的矿石柱在添加MFD后再次开始快速浸出。这些结果非常有希望。 如果MFD可以在堆浸条件下使黄铜矿脱钝化，则这可以使黄铜矿矿石与辉铜矿矿石一样容易堆浸。这将是一个重大突破，从根本上改变铜矿开采的经济状况。拟议的研究将集中在开发一个可行的黄铜矿堆浸工艺使用MFD。 具体目标包括：* 1使用MFD进行柱生物浸出实验，以确定最佳工艺条件 * 2培养铁和硫氧化细菌，使其在所需水平上对MFD具有抗性 * 3改进用于测量浸出溶液中MFD浓度的分析方法 * 4确定MFD（如果有的话）对铜SXEW的影响 * 5测量MFD催化浸出的反应动力学 * 6开发使用MFD的堆生物浸出的综合数学模型 * 7开发黄铜矿矿石和精矿的搅拌罐生物浸出的并行技术 * 8确定MFD催化作用的基本机理 * 9测试与MFD具有相同官能团的替代有机化合物 *10测试其他重要硫化物矿物的MFD **

Roughly 80% of the world's copper comes from the copper sulfide mineral chalcopyrite, CuFeS2. Typically, chalcopyrite ores are concentrated and subsequently smelted to obtain high purity copper. However, the grades of these primary copper ores have been steadily decreasing, which renders this route less than economical for many of today's low-grade ores. A potential low-cost alternative to process low-grade copper ores is heap bioleaching. However, chalcopyrite is notoriously difficult to leach due to mineral passivation, and commercial application of heap bioleaching has thus far been limited to secondary copper sulfide (chalcocite, Cu2S) ores. Heap bioleaching of low-grade chalcopyrite ores (combined with solvent extraction and electrowinning, or SXEW) has been the “holy grail” of hydrometallurgy for many years, and several methods have shown some promise, including the use of extreme thermophilic microbes in hot heaps where pyrite is first oxidized to generate heat, and the use of chloride as a catalyst. However, hot heaps are unreliable and difficult to control, and chloride is extremely corrosive.******Recent work at UBC suggests that it is possible to catalyse the leaching of chalcopyrite with certain soluble species. Electrochemical tests on a chalcopyrite electrode showed that small amounts of a proprietary (albeit inexpensive and readily available) soluble organic compound (which will be referred to as MFD) depassivated the electrode. Preliminary results from column and tank leaching experiments show that MFD is a powerful catalyst in ferric leaching. Adding MFD prevented passivation and enhanced the leaching rate significantly. Also, a column of ore which had stopped leaching began to leach rapidly again upon addition of MFD.******These results are very promising. If MFD can depassivate chalcopyrite under heap leaching conditions, then this could render chalcopyrite ores as easy to heap leach as chalcocite ores. This would be a major breakthrough which fundamentally alters the economics of copper mining.******The proposed research will focus on developing a viable heap bioleaching process for chalcopyrite ores using MFD. Specific objectives include:*** 1 Conduct column bioleaching experiments with MFD to determine optimum process conditions*** 2 Culture iron and sulfur oxidizing bacteria to be resistant to MFD at the levels required*** 3 Refine analytical methods for measuring MFD concentrations in leach solutions*** 4 Determine the impact of MFD (if any) on copper SXEW*** 5 Measure the reaction kinetics of MFD-catalyzed leaching*** 6 Develop a comprehensive mathematical model of heap bioleaching with MFD*** 7 Develop a parallel technology for stirred tank bioleaching of chalcopyrite ores and concentrates*** 8 Determine the fundamental mechanism of the catalytic effect of MFD*** 9 Test alternative organic compounds which share the same functional groups as MFD***10 Test MFD on other important sulfide minerals**