Process design for gallium recovery including lixiviant regeneration

Abstract

Gallium extraction from a zinc smelter waste stream is designed, discussed, and evaluated. Gallium is separation is achieved via precipitation behavior from zinc and via caustic leach behavior from iron. The process developed showed a recovery of 38% of the gallium from the zinc smelter waste product. The process economics are developed to show the conditions under which the process may be operated economically to recover gallium from this resource. The economic analysis is useful to identify the specific operations and factors that contribute to the process costs. One of the most significant parameters that affects cost is the acid consumption of the leaching unit operation and the soda ash consumption of the pH adjustment unit operation. In order to address this large cost parameter a novel process for recovering sulfuric acid and soda ash from the leach solution after metals have been precipitated is developed and studied. This novel operation has the potential to significantly impact a range of industries that are consumers of chemicals including any mining project where reagent consumption is a major cost item.