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The overall performance of hydrometallurgical leaching operations can be limited by the presence of various types of insoluble layers coating the surface of the treated solids. The attrition-leaching process, which is carried out in a stirred reactor containing millimetric beads, can partially overcome this problem and increase the extraction yield by physically abrading the layers. Through a comparative analysis of three different systems, this work develops a constructive discussion of the attrition-leaching process. The systems of interest are (i) mineral carbonation of ferronickel slag, (ii) dissolution of a chalcopyrite concentrate in sulfuric media, and (iii) dissolution of spent Ni-MH battery black mass powder in sulfuric media. In the case of ferronickel slag and chalcopyrite, the reaction yields are improved by a factor of 10 with attrition-leaching compared to leaching only, while there is no yield improvement in the case of Ni-MH black mass batteries, highlighting that the layers observed on the grain surface do not interfere with the leaching reaction. Despite very different system chemistries and conditions, the particle size distribution is similar for the three materials, showing that particles’ behavior is controlled by the attrition environment. This work offers a simple setup for investigating the potential improvements of the kinetics and yields of leaching reaction due to concomitant attrition. It also allows a fundamental study of the physico-chemical processes involved, by testing whether a leaching reaction is hindered by an in situ passivation at the surface of a material.
Laskar et al. (2024) studied this question.