Abstract

Recent studies of metal leaching using monosodium glutamate have shown promising results of this being an alternative to conventional leaching reagents. However, limited information is available covering the treatment of leaching solutions and the final recovery of metals. In this regard, this article presents an experimental study on the precipitation of copper from glutamate solutions using sodium hydrosulfide (NaHS), as a simple and efficient route for the processing of leaching solutions from this new system. Synthetic pregnant leach solutions (PLS) with varying copper total concentrations [CuT] and glutamate concentrations were used. The effects of [CuT], [CuT]:[NaHS] molar ratio and glutamate concentration on the particle size distribution and copper recovery were investigated. The results revealed that higher [CuT] led to smaller particle sizes, with the P90 decreasing from 106 mu m to 60.7 mu m and 73.2 mu m for Cu concentrations of 1 g/L, 2.5 g/L, and 5 g/L, respectively. The [CuT]:[NaHS] molar ratio reduced the P90 particle size, from 60.7 mu m to 56.4 mu m and 7.44 mu m as the molar ratio increased from 1:0.8 to 1:1 and 1:1.2, respectively. Copper recovery from glutamate solutions increased with higher molar ratios, achieving values of 70.95 %, 88.24 %, and 99.55 % for molar ratios of 1:0.8, 1:1, and 1:1.2, respectively, agreeing with copper recovery values of other chemical systems. The glutamate concentration had minimal impact on particle size but affected copper recovery, with a decrease from 88.24 % to 85.83 % when increasing the glutamate concentration from 0.5 M to 1 M. X-ray diffraction (XRD) analysis confirmed the presence of pure covellite with hexagonal phase in the precipitates. These findings contribute to understanding copper precipitation dynamics from glutamate solutions using NaHS and have implications for optimizing copper recovery processes in the perspectives of the advent of alkaline leaching of copper ores.