This is both a feature article in IM’s forthcoming September issue and a research theme of Australia’s Minerals Down Under Flagship. The latter is working closely with mining companies, SMEs and mining technology service providers to develop technology-based solutions to address the challenges of increasing production costs, declining ore grades, complex ores with higher levels of impurities and increasing pressure from regulators to improve environmental performance.Swirl Flow technology – This patented technology was developed in conjunction with Queensland Alumina Limited (QAL) and is now used in 15 precipitation tanks approximately 30 m tall and 10 m in diameter at QAL. Swirl Flow offers many benefits including reduced scale formation on tank walls, lower capital costs, lower energy consumption and easier restart after power failures. In addition to applications within the alumina industry there are many other applications for Swirl Flow in other mineral processing operations as well as outside the minerals industry.
New thickener feedwell – the first installation of a patented feedwell concept for use in gravity thickeners has now been installed. Once the new feedwell concept is proven through prolonged full-scale performance, it is expected to lead to significant takeup across the minerals industry – in which there are more than 5,000 gravity thickeners – and potentially other industries.
Direct solvent extraction – CSIRO has patented a Direct Solvent Extraction (DSX) process for extracting nickel, cobalt, copper and zinc directly from the aqueous leach solution into an organic solution and then stripping the metals back into aqueous solution with acid, thereby purifying and concentrating the valuable metals. This avoids the need to have an intermediate purification step involving precipitation of these values as either a mixed hydroxide or sulphide product. The key innovation has been the use of a (synergistic) mix of two commercially-available extractants to achieve the desired separation in a single process step.
Thiosulphate leaching of refractory gold ores – Minerals Down Under researchers have been working in close collaboration with a major gold mining company to assist their development of a pressure oxidation-thiosulphate leaching process for treating sulphidic-carbonaceous refractory gold ores. The process, which incorporates a CSIRO-patented resin elution procedure, has moved to the construction of a demonstration plant. If successful, this will be the world’s first demonstration of a thiosulphate leaching and resin in pulp process for recovering gold.
In-situ/in place leaching of oxide gold deposits – CSIRO has been researching the problem of in-situ leaching of gold deposits for some years. This work has focussed on using gold-complexing reagents (lixiviants) other than cyanide and oxidants that can function effectively in an anaerobic environment. CSIRO jointly holds with Murdoch &University, intellectual rights on a specific non-cyanide lixiviant-oxidant combination of this type. It uses sodium thiosulphate as a lixiviant and ferric EDTA as an oxidant. For in-situ applications it has been decided to focus on gold mineralisation in which pyrite and other sulphides as well as carbonaceous materials are absent, such as deeply weathered gold ores. Many such deposits are known, especially in the southern parts of Western Australia and South Australia, where such mineralisation is present in ore accumulations which are either too small, low grade, deeply buried or far from a suitable mill to be economically viable. Seven organisations have agreed to sponsor ongoing research in this area.
The Flagship’s contributions to thickener technology advances through an AMIRA project since 2007 amount to a delivered value of about A$100 million (NPV) with potential for at least another A$100 million (NPV) over the next five years.
CSIRO’s Synergistic Solvent Extraction technology is estimated to have delivered at least A$100 million (NPV) to the nickel industry, with potential for at least another A$200 million (NPV) over the next five years.
The 2009 Parker Centre Award for Research Collaboration was presented to the Flagship’s Dr Jian Li and her Impacts of Mineralogy on Hydrometallurgy project team. The award recognised the most effective collaboration within the Centre in aCRC funded research project. The report on the project stated that: “The project involving teams from CSIRO and Curtin in year one, is another excellent example of a successful multi-disciplinary/multi agency team. The significant level of research collaboration and individual scientist interaction has developed in less than 12 months, many of the researchers had not even met before the projuect commenced. It is encouraging to see the very positive scientific contribution being made by researchers from Curtin University Applied Geology and Applied Physics, who do not have a hydrometallurgy/mineral processing background.”
The project’s fundamental research is focussed on understanding nickel and/or copper losses during processing and increasing the dissolution kinetics of refractory nickel-bearing and/or copper-bearing mineral phases.
For more details on any of these contact Dr John Farrow, +61 8 9334 8020, John.Farrow@csiro.au