Laboratory study: simultaneous leaching silver-bearing low-grade manganese ore and sphalerite concentrate

Rich silver-bearing low-grade manganese ore can be found in great supply in China's Yunnan Province. This paper describes an experiment in which silver-bearing low-grade manganese and sphalerite concentrate were leached and manganese, silver and zinc recovered. First the chemical composition and mineralogical structure of silver-bearing low-grade manganese ore were determined. Then, by studying the effects of adding amounts of reducing agents and sulfuric acid as well as reaction time, the temperature and the liquid-to-solid ratio on the leaching process, optimum technological conditions were achieved. The leaching rate of manganese reached 98%. The silver in the slag was leached by adding an ammonia solution. By adding hydrazine hydrate, sponge silver with purity of up to 99% was obtained. The recovery rate of silver reached 87%. (C) 2004 Elsevier Ltd. All rights reserved.