High Efficiency Electro-Refining for Direct Capture of Saleable Metals

78481S Electrowinning is an important process used in the mining and refining of many valuable metals. Conventional electrowinning technologies are economically practical only at high metal concentrations, greater than 1000 mg/L. As a result, a large amount of metal value is lost as toxic waste that must be treated for proper discharge. There are also large aqueous sources laden with valuable heavy metals that are too dilute to be economically utilized as a resource. This project will develop a high-efficiency, electro-refining system for the direct recovery of economically valuable metals from a variety of aqueous sources. The core of this system is a unique electrolytic technology, which allows control over the key operating parameters that determine the electrowinning selectivity for individual metals. The technology will be reagentless, simple in design and process flow, low cost, and mobile, and will enable economic metal recovery and separation to very low concentrations, less than 1 mg/L. In Phase I, the operating parameters and performance specifications for a flow-through electrowinning system will be determined for the efficient recovery and selectivity of a number of target heavy metals. Electrolytic cell design and materials will be tested and evaluated for performance and longevity. This results will be used to design a pilot-scale flow-through electro-refining system that will be constructed and demonstrated during Phase II. Commercial Applications and Other Benefits as described by the awardee: The high-efficiency electro-refining system should allow for the selective recovery of metals from liquid streams down to very low concentrations. This should provide more complete utilization of available metal resources and greatly reduce toxic metal discharge and treatment costs. The primary end-users of the technology are the mining, refining, metal finishing, semiconductor/electronics, and environmental remediation industries.