Leaching Behavior of Gold and Silver from Concentrated Sulfide Ore Using Ammonium Thiosulfate

Mooki Bae,Hyunju Lee,Sookyung Kim,Jeongsoo Sohn,Donghyo Yang

doi:10.3390/met10081029

Abstract

Ammonium thiosulfate is an alternative lixiviant for the hydrometallurgical treatment of sulfide gold ores. The present study is primarily focused on ammonium thiosulfate leaching of gold (Au) and silver (Ag) from the sulfide ore (Sunshin mine in Korea). The main chemical composition of the concentrate was Au (84 ppm), Ag (852 ppm), Fe (18.9%), Si (23.2%), and S (21.1%). The effects of various parameters on the process, such as leaching time (1–4 h), ammonium thiosulfate concentration (0.05–0.5 M), copper sulfate (CuSO4), concentration (0.05–0.25 M), solid to liquid ratio (0.2–0.5), and reaction temperature (40–60 °C) were systematically examined. Optimum Au leaching efficiency (>99%) was obtained under the following leaching conditions: 0.5 M ammonium thiosulfate with 0.05 M CuSO4 concentration, 0.2 S/L ratio at 60 °C for 2 h. The results indicate that the behavior of Ag was similar to that of Au. Almost complete dissolution of Ag occurred under following leaching conditions: 0.5 M ammonium thiosulfate with 0.05 M CuSO4 concentration at 60 °C for 4 h. This study would be useful in understanding the eco-friendly leaching systems of Au and Ag during the hydrometallurgical process of sulfide gold ore.

Highlights

For over 100 years, cyanide has been the most common leaching reagent for gold (Au) recovery from ores and concentrates
Of 40 ◦ C to 60 ◦ C, and >99% leaching efficiency is reached at 60 ◦ C after42ofh
The ammonium thiosulfate leaching process has been investigated for the recovery of

Summary

Introduction

For over 100 years, cyanide has been the most common leaching reagent for gold (Au) recovery from ores and concentrates. Cyanide has advantages including high Au recoveries, robustness, and relatively low costs, it is highly toxic and harmful to human health and the environment [1,2]. Various alternative lixiviants, such as halide, thiourea, and ammonium thiosulfate, have been extensively researched in the last few years [1]. In the 1990s, few researchers conducted Au leaching studies using ammonium thiosulfate with cupric ions acting as an oxidant [4,5,6,7].

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Conclusion