Advances at the Sulphide Mineral/Solution Interface: Improved Metal Extraction and Energy Storage

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Metals vital materials for modern civilization are required for their ubiquitous use as conductors, as building materials and in transportation. Metals such as copper, zinc and nickel are generally mineralized in the form of sulphides. The main economic production methods for these metals from their sulphides essentially relies on a scaled-up version of Bronze age technology: smelting or roasting. Because metals consumption has increased at a compound rate of approximately 3% per annum since 1850, and because ore grades are declining worldwide, metal markets are at a crossroads: in future how will we economically and responsibly extract these metals? To answer this question, research in the area of aqueous processing of the copper sulphide, chalcopyrite, has been ongoing worldwide for over 50 years with no viable solution because chalcopyrite resists oxidative breakdown in most practical leaching environments. Thankfully, detailed studies of the chalcopyrite/solution interface, using modern electrochemical and surface analysis techniques, have led to a breakthrough. A soluble organic catalyst that overcomes this problem has been identified. This proposal discusses a program to confirm the mechanism of catalysis and to identify new catalysts that will perform as well or better. Further, we will explore the use of the catalyst system for other sulphide minerals such as pentlandite (nickel) and sphalerite (zinc). ******The electrochemical studies aimed at chalcopyrite leaching have led to another discovery that could change the metals industry. To date, extractive industries have used sulphide minerals for producing copper, nickel and zinc. However, these minerals possess intrinsic properties that could be used for purposes other than metal production. Indeed, for example, chalcopyrite (CuFeS2) is a well known natural semiconductor that has been studied for use as cathode material in lithium batteries and as an active layer in photovoltaics. There exists a dichotomy between the current use of sulphide minerals for metal production and its potential application as an energy material. But what if we could combine these two uses? What if we could employ these natural, readily available materials for the purposes of energy storage and production as well as for a source of metals? Using the electrochemical and surface analysis methods that are central to this proposal, we will explain how sulphide mineral flow batteries could revolutionize the metals industry.