Application of LA-ICP-MS to process mineralogy: Gallium and germanium recovery at Kipushi copper-zinc deposit

Abstract

In the field of process mineralogy, laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) is a valuable tool that can complement other mineralogical techniques used to characterise orebodies and concentrator performance. Many economic metals are present at ultra-low levels as solid solution or as inclusions within minerals and require complex recovery techniques to separate them from the bulk ore. Understanding metal occurrence is necessary for implementing the proper recovery strategies. LA-ICP-MS is a cost-effective and versatile method of measuring precious-metals and other economic trace-elements in solid solution in various types of mineral phases while achieving low detection limits. To demonstrate the practical uses of LA-ICP-MS to process mineralogy, XPS has collected data from a sulphide-rich heavy liquid separation and shaking table concentrate from the Kipushi Cu-Zn deposit, Katanga, Democratic Republic of Congo. In addition to Cu and Zn, Kipushi Corporation SA (KICO) is currently investigating strategies for concentrating Ge and Ga. A combination of gravity separation and recovery of Ge and Ga through flotation of Zn and other base metal sulphides are being considered. The objective of the LA-ICP-MS analysis was to determine the proportion of Ge and Ga present in solid solution in sulphides and in discrete mineral phases. The results indicate that sphalerite carries Ga in solid solution (42.5 ppm, representing 54% of the Ga deportment) and chalcopyrite hosts Ge in solid solution (2462 ppm, representing 21% of the Ge deportment). Discrete phases host the remaining portions of Ga and Ge. The deportment information can be used to guide flowsheet development in order to optimize recovery.