Work

Secondary Phase Formation During Electrokinetic in Situ Leaching of Intact Copper Sulphide Ore

Year: 2022

Type: article

Abstract: Electrokinetic in situ leaching (EK-ISL) of copper sulphides is a novel mining technology aimed at recovering copper from ore bodies without physical excavation, thereby significantly reducing the environmental footprint of the mining operation. So far, its proof of concept has been demonstrated at the cm-scale. Its viability at larger scale is, however, highly dependent on developing a comprehensive understanding of the geochemical processes occurring inside the pore space of the intact rocks during leaching. One of the critical issues that has shown to impact the efficiency of conventional (hydraulically driven) copper sulphide leaching operations is the formation of secondary layers. So far, the details of their formation have only been studied under ex situ conditions and for ground samples. These secondary leaching products are often proposed as the main culprit for the successively diminishing copper recoveries in hydrometallurgical systems. Therefore, this study was aimed at a detailed characterisation of the secondary leaching products under EK-ISL induced leaching conditions and how they evolved over time. We conducted time-dependant leaching tests with intact core samples with either ferric chloride or ferric sulphate as lixiviant. SEM-EDS and laser Raman microspectroscopy showed the formation of elemental sulphur as a result of the oxidation of longer-chain polysulphides. The neo-formed phases showed to slow down copper recovery, yet did not completely halt the leaching progress. Our conceptual model of the secondary layer formation suggests that the sustained dissolution of polysulphides during EK-ISL-induced leaching under the induced geochemical conditions exposes new mineral surfaces to attack. Importantly, this creates the opportunity for secondary phase re-solubilisation and therefore enhanced copper recovery.

Source: Hydrometallurgy

DOI: 10.1016/j.hydromet.2022.105993

Authors: Pablo Ortega-Tong, James Jamieson, Benjamin C. Bostick, Andy Fourie, Henning Prommer

Institutions: The University of Western Australia, Lamont-Doherty Earth Observatory, Columbia University, CSIRO Land and Water

Language: English

Topic: Electrokinetic Soil Remediation Techniques

Subfield: Electrical and Electronic Engineering

Field: Engineering

Domain: Physical Sciences

Open Access status: hybrid

Estimated APC paid: $3,850

Funder: Minerals Research Institute of Western Australia