Atomic Force Microscopy and Raman Microspectroscopy Investigations of the Leaching of Chalcopyrite (112) Surface

Gujie Qian,Christopher T Gibson,Allan Pring,Sarah Harmer-Bassell

doi:10.3390/min10060485

Abstract

The aim of this study was to determine the reactivity of the chalcopyrite (112) surface under industrially relevant leaching conditions. Leaching of the chalcopyrite (112) surface was carried out at approximately pH 1 and in the presence of 0.01 M ferric or ferrous. The atomic force microscopy (AFM) and Raman microspectroscopy analyses suggested that the chalcopyrite (112) surface was relatively inert, with no formation of elemental sulfur observed over 42 days of leaching. In addition, it was found that the distribution of Fe-S and Cu-S bonds was always negatively correlated, as revealed by Raman analysis. This suggested that the breakage of the Fe-S and Cu-S bonds did not occur concurrently at a specific reaction site. The rate of variation of surface roughness, as reflected by AFM data, also suggested that leaching of the chalcopyrite (112) surface in the ferric or ferrous solution medium likely occurred more rapidly in the initial stage (fewer than seven days) than in the later stage (after seven days).

Highlights

Chalcopyrite (CuFeS2 ) is one of the most abundant copper-bearing minerals and the primary source of copper in the world, accounting for nearly 70% of the Earth’s copper [1,2]
−1 consistent with those reported in the literature [15,16,17,18], while those below 200 cm−1 are scarcely consistent with those reported in the literature [15,16,17,18], while those below 200 cm are scarcely reported [17]
Chalcopyrite surface was possibly due to precipitation of secondary sulfate from data showed some variations in the surface roughness for samples leached in the presence of ferric leachate

Summary

Introduction

Chalcopyrite (CuFeS2 ) is one of the most abundant copper-bearing minerals and the primary source of copper in the world, accounting for nearly 70% of the Earth’s copper [1,2]. Copper is largely extracted from chalcopyrite using pyrometallurgy (smelting) after concentration by mineral flotation [3], which is a high energy consuming method and associated with significant environmental concerns (e.g., release of toxic sulfur-containing gases). Hydrometallurgy is an alternative method to pyrometallurgy which has been increasingly applied to extract copper from ores, low-grade chalcopyrite ores [4]. Chalcopyrite is highly refractory with relatively slow leaching kinetics, which limits the application of hydrometallurgy in the mining industry [2,3]. While complete chalcopyrite leaching has been achievable [1,5], slow and incomplete leaching has often been observed under certain conditions, in particular, at relatively low temperatures. A maximum of 85% of chalcopyrite has been leached at 43 ◦ C and pH 1.0, and the remaining 15% of chalcopyrite was found to be resistant to leaching [6], which is not immediately explainable

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