OBJECTIVES

Nickel production is a major industry in Western Australia (laterites and sulfides). One challenge for the industry is the losses of both nickel and cobalt that occur during pressure acid leaching of laterite ores. The full extent and mechanism(s) of these losses need to be understood to increase extraction efficiency. Industry also needs to understand the factors affecting the precipitation of metallic nickel powder by hydrogen reduction of nickel sulfate solutions.

Another challenge is that process water, particularly in WA, is seldom ideal. Previous research has determined the effect of water quality on nickel extraction by pressure leaching of laterites, and how additives can be used to improve nickel recoveries. The effects of process water quality on the pressure oxidation of nickel and copper sulfides also need to be investigated, as does the potential of improving metal extraction by using additives.

This project aims to assist industry to improve process efficiency and metal extraction from oxide and sulfide ores through:

• gaining an understanding of nickel and cobalt losses during pressure acid leaching of laterites in terms of leach feed mineralogy and leach residue composition, morphology (shape) and mineralogy
  
• developing methods for the pressure oxidation of nickel sulfide ores and copper sulfide ores, and describing the effects of water quality and additives on metal extraction
  
• investigating the use of homogeneous nucleation catalysts in nickel powder production
  
• investigating the effect of additives and impurities on the nickel powder produced by hydrogen reduction, and also studying hydrogen reduction of copper and cobalt.

INDUSTRY BENEFITS

• greater nickel recovery during high pressure acid leaching of nickel laterites through understanding how nickel losses occur during leaching
  
• identification of process conditions for copper and nickel sulfide pressure oxidation informed by fundamental understanding of the impacts of process water quality and additives on autoclave reaction chemistry and thus metal extraction
  
• higher nickel recovery by increasing the number of densifications possible in the production of metallic nickel powders by hydrogen reduction without loss of product quality.

RESEARCH TEAM
Dr Robbie McDonald (Project Leader)
Dr David Muir
(CSIRO Minerals)

PROJECT DURATION
2005-2008