This study focuses on the development of an alkaline leaching hydrometallurgy process for the recovery of tungsten from WC/Co hardmetal sludge, and an examination of the effect of the process parameters on tungsten recovery. The alkaline leaching hydrometallurgy process has four stages, i.e., oxidation of the sludge, leaching of tungsten by NaOH, refinement of the leaching solution, and precipitation of tungsten. The WC/Co hardmetal sludge oxide consists of WO3 and CoWO4. The leaching of tungsten is most affected by the leaching temperature, followed by the NaOH concentration and the leaching time. About 99% of tungsten in the WC/Co hardmetal sludge is leached at temperatures above 90oC and a NaOH concentration above 15%. For refinement of the leaching solution, pH control of the solution using HCl is more effective than the addition of Na2S·9H2O. The tungsten is precipitated as high-purity H2WO4·H2O by pH control using HCl. With decreasing pH of the solution, the tungsten recovery rate increases and then decrease. About 93% of tungsten in the WC/Co hardmetal sludge is recovered by the alkaline leaching hydrometallurgy process.

Abstract
 1. 서 론
 2. 실험방법
 3. 결과 및 고찰
 4. 결 론
 References

• 이길근(부경대학교 신소재시스템공학과) | Gil-Geun Lee (Department of Materials System Engineering, College of Engineering, Pukyong National University) Corresponding author
• 권지은(부경대학교 신소재시스템공학과) | Ji-Eun Kwon (Department of Materials System Engineering, College of Engineering, Pukyong National University)