Nickel (Ni) is one of the main elements used in stainless steels, coinage, rechargeable batteries and magnets. It is an extremely important export commodity for the Australian mining sector as the country is the fourth largest producer of nickel internationally (90% in Western Australia). However due to the continued use of the reserves of high-grade nickel sulphide ores, laterite ores have now become an important source from which this element is extracted. The use of mineralized surficial material as a source of metals has increased in recent years due to the diminishing availability of traditional primary mineralization. Furthermore, because these ores occur at the surface, and therefore have easy access for mining, they can be far more economic than primary ores as a source of metals. This is true even though the actual concentrations of the economic minerals are lower than in more traditional primary ores. However, there is a significant problem associated with extraction of metals from surficial deposits in that the relative refractory nature of goethite (a secondary hydrated iron oxide mineral produced by weathering iron ores) present can severely limit the extractive efficiency of both chemical and bacteriological agents. Consequently, even relatively high grade deposits can be extractively largely sterile. Therefore it would be economically extremely beneficial to be able to characterise the degree of extractability, and therefore economic value, of ores prior to establishing costly plant facilities on site and only then find out that the ores being processed are refractory. At present the test procedures involved in determining the extraction potential of these ores includes processes that can last over six months and the expenditure of a significant amount of money with concomitant waste of time if the ores prove to be largely economically un-extractable. Characterization of nickel laterite ores suited to heap leach processing is therefore important in order to select those that are the most reactive and provide the highest recovery of the metal. Heap leaching, albeit an expensive and time consuming process, is the main technique used to extract Ni from nickel laterites. Consequently, the research detailed in this thesis is designed to develop a fast extractive chemical leaching protocol to assess the reactiveness of nickel laterites to heap leaching regimes and thereby overcome the significant expenditure and time requirements associated with the traditional longer term field trials now used to determine nickel extractability.
|Publication status||Unpublished - 2013|