Ammoniacal Solvoleaching of Copper from High-Grade Chrysocolla

Abstract

The copper silicate ore chrysocolla forms a large potential copper resource, which has not yet been fully exploited, due to difficulties associated with its beneficiation by flotation and metallurgical processing. Direct acid leaching of chrysocolla causes silica gel formation. Therefore, in this work, the feasibility of solvometallurgical methods to leach copper from high-grade chrysocolla while avoiding issues with silica gel formation was assessed. Ammoniacal solvoleaching was performed with a solvent comprising the chelating extractant LIX 984 N or the acidic extractant Versatic acid 10 in an aliphatic diluent (ShellSol D70 or GTL Fluid G70), combined with a small volume of aqueous ammonia. In the three-phase system, aqueous ammonia dissolves copper from milled and sieved chrysocolla, while copper is simultaneously extracted to the organic phase, releasing ammonia that can be reused for further extraction. The best results were obtained with LIX 984 N as extractant: using a 50 vol% LIX 984 N solution, about 75% of copper could be extracted after 60 min of leaching at 25 °C. The stripping of copper from the pregnant leach solution was optimized. Quantitative stripping of copper was achieved with 1.89 M sulfuric acid and the final aqueous solution of copper sulfate had a concentration of 33 g L−1. Experiments in a leaching reactor (1 L) and small battery of mixer-settlers (3 stages, 35 and 143 mL effective volume in the mixer and the settler, respectively, per stage) were successfully conducted and allowed to recover copper with a purity of 99.9%. A conceptual flow sheet has been developed. Graphical Abstract

Combined Hydro–Solvo–Bioleaching Approach toward the Valorization of a Sulfidic Copper Mine Tailing

“…While roasting increased the leachability, less than 70% of the copper was leached via conventional ammoniacal leaching. To increase the efficiency of the process, a simultaneous leaching and SX were investigated. , In this process, the solid (S) is allowed to contact with two immiscible liquid phases, that is, the aqueous lixiviant phase (A) and the organic extractant phase (O). The solid is leached by the aqueous phase, but the leached metals are immediately extracted to the organic phase.…”

“…To increase the efficiency of the process, a simultaneous leaching and solvent extraction (SX) was investigated. 35,36 In this process, the solid (S) is contacted with two immiscible liquid phases, i.e. the aqueous lixiviant phase (A) and the organic extractant phase (O).…”

Solvometallurgical Process for the Recovery of Copper from Chrysocolla in Monoethanolamine

“…22 Leaching of low-grade complex copper ore in an ammonia−ammonium chloride system readily extracted 63−100% of the malachite phases but only 2−37% of the chrysocolla phases. 24 A solvometallurgical leaching system consisting of a chelating extractant, an aliphatic diluent, and aqueous ammonia obtained the best result of 75% copper extraction yield from high-grade chrysocolla ore. 9 An unwanted stable emulsion was formed at the interface between the organic and aqueous phase during the subsequent stripping process, which then required the addition of a modifier. Solvometallurgy is a relatively new approach in the extractive metallurgy that may offer advantages over hydrometallurgical processing, for example, minimizing problems with silica gel and obtaining a higher leaching selectivity compared to acid leaching.…”

Recovery of cobalt from lithium-ion battery cathode material by combining solvoleaching and solvent extraction

“…For example, Gijsemans et al used the chelating extractant LIX 984 N (equivolume mixture of 2-hydroxy-5-nonylacetophenone oxime and 5-dodecylsalicylaldoxime) as lixiviant to solvoleach copper from chrysocolla, after which the copper-loaded organic phase was directly stripped by a mineral acid. 28 Using non-aqueous lixiviants during solvoleaching could avoid the formation of toxic and/or dangerous gasses compared to leaching with conventional mineral acids, which is a potential benefit. 26 It has been demonstrated that process intensification by integration of unit operations not only reduces the operating costs but it also improves the safety, greenness and energy efficiency of processes.…”

“…[29][30][31] For example, in the process of Gijsemans et al, the number of solvent extraction steps was reduced. 28 If their process would be up-scaled in countercurrent mode, it would require fewer mixer-settler units and smaller volumes of chemicals, and would produce less aqueous waste. Furthermore, several recent studies on LIB recycling have shown that the aluminium and copper current collectors can also reduce cobalt(III) during the leaching of cathode material, which could avoid pre-separation steps and in turn reduce energy costs.…”