High Efficiency Electro-Refining for Direct Capture of Saleable Metals

Electrowinning is a widely used process method for primary mineral extraction and refined metal production; however, conventional technologies have economic and efficiency limitations that leave significant resources either unutilized or lost to waste discharge. The major challenges for electrowinning technologies are increasing production efficiency; eliminating waste; and combining separation, refining, and production into a single process. This project will develop a unique, high-efficiency electrowinning technology that can capture metals from aqueous streams, especially at low concentrations (<500 mg/L), and simultaneously produce metals and reduced metal oxides. During Phase I, a number of process conditions and system configurations were evaluated for removing several different metals from acid solutions, without the use of additives. Unique capabilities in energy efficiency, waste treatment, and material production were demonstrated at low concentration (200 mg/L). In particular, it was demonstrated that copper or cuprous oxide could be produced for about $0.30 per pound, that iron ferrite could be produced directly from solution for less than $0.15 per pound, and that arsenic could be removed to achieve discharge levels. During Phase II, process conditions will be optimized for more selective production of specific products (metals and metal oxides) from feed streams relevant to solvent extraction and mine waste, using the pilot-scale reactor produced in Phase I. A pilot-scale system, incorporating several reactors, will be designed, fabricated, and demonstrated as the vehicle for transitioning the technology to one of several potential end-users. Commercial Applications and other Benefits as described by the awardee: Commercial applications and market entry will initially focus on the metals recovery and reduced oxide products markets. These markets are very large (several $ billion each), the economic benefits are clear, and interested companies are numerous. For the production of cuprous oxide and iron ferrite alone (not including metals recovery), the internal rate of return for a licensing venture is estimated at 152%, with a net present value of about $145 million