HYDROMETALLURGICAL PROCESSING OF NICKEL LATERITES- A BRIEF OVERVIEW ON THE USE OF SOLVENT EXTRACTION AND NICKEL/COBALT PROJECT FOR THE SEPARATION AND PURIFICATION OF NICKEL AND COBALT

In this study, a brief overview of the solvent extraction (SX) application for the separation and purification of nickel and cobalt in hydrometallurgical processing of laterite nickel ores is presented. This paper consists of two parts: firstly, the SX of nickel and cobalt from sulphate leach solutions is described; and secondly, the development of hydrometallurgical plants for the processing of laterite nickel ores that involve solvent extraction technique is discussed. The most important extractants are shortly given in the first part of the study. It is seen that the extraction and separation of nickel and cobalt from the impure leach solution of laterite nickel ores can be performed by either using a single extractant system that is called as a direct solvent extraction (DSX) or a mixture of two or more extractant which is known as a synergistic solvent extraction system (SSX). Mixed sulphide precipitation (MSP) and mixed hydroxide precipitation (MHP) processes are mentioned. This paper is also addressed advantage and disadvantages of each extraction system. It is shown that capital investment expenditure, operational investment expenditure and mineralogical content are the most important factors that can affect the selection of the appropriate hydrometallurgical process for lateritic nickel ore