Separation of Silver from a Zinc Sulfide Concentrate by a Co-smelting Process

Abstract

The main purpose of this study is to characterize and separate silver from a zinc sulfide concentrate through co-smelting with lead oxide dust. This article reports the optimization of process parameters, such as flux composition, co-smelting temperature, flux dosage, and charging material compositions, on the silver separation rate and resultant zinc sulfide concentrate grade. A maximum silver recovery of 97.36%, zinc sulfide concentrate grade of 43.91%, and 98.25% crude lead enriched silver are obtained under the optimized condition of temperature 900°C, smelting duration 120 min, 27.5 wt.% zinc sulfide concentrate, and 15.0 wt.% lead oxide dust, flux composition ${{W_{\text{NaOH}} } \mathord{\left/ {\vphantom {{W_{\text{NaOH}} } {W_{{{\text{Na}}_{ 2} {\text{CO}}_{ 3} }} }}} \right. \kern-0pt} {W_{{{\text{Na}}_{ 2} {\text{CO}}_{ 3} }} }} = 1/ 3$. This co-smelting process was proven effective to separate silver from zinc sulfide concentrate and produce a higher grade zinc sulfide concentrate. Especially, it was found to be effective to separate some associated impurities from zinc sulfide concentrate, such as arsenic, cadmium, fluorine, and chlorine etc.