Production of Zn powder by alkaline treatment of smithsonite Zn-Pb ores

Abstract

A production process for Zn powder by alkaline treatment of an oxidized Zn ore smithsonite (ZnCO3) is studied. It is found that over 85% of both Zn and Pb, and less than 10% of Al is leached from the ore when the leaching operation is conducted at over 95 °C using 5 M NaOH solution as leaching agent. Leaching of Pb is improved with the addition of NaCl to the leaching systems. The leach solution is subjected to electrolysis for the production of metallic Zn after Pb is separated by sodium sulfide after filtration. The NaOH solution is recycled to the next leaching operation after most of the Zn is electrowon. Most of the operational cost for this process comprises the consumption of electricity for electrolysis, NaOH, and energy required for heating.