The IsaMill™ - 25 Years of Stirred Milling


Ion Gurnett

Mount Isa Mines (MIM) had two significant liberation issues in the 1980's.  The first being the inability to find a technical solution for the economic development of the massive McArthur River Pb/Zn deposit.  The second was the continuing deterioration in the metallurgical performance at the Mt Isa Pb/Zn concentrator as a result of the increasing ore body complexity.  In both cases, grinds as fine as P80 7um had been identified to adress the liberation issues.  Despite years of research and investigation, an adequate solution was not found using exisiting technology or processes available within the mining industry.  Conventional grinding technology consumed uneconomic levels of specific energy and even when the target size was achieved, flotation response was poor - primarily due to the impact of steel grinding media on surface chemistry.  MIM then looked outside the mining industry for cross over technology from other industries that had to grind fine, eventually collaborating with the world leader Netzsch-Feinmahltecknik to develop to IsaMill technology onsite at Mt Isa.  The first commercial installation was at Mt Isa in 1994 and then it became the enabling technology at McArthur River in 1995.  Based on the success of these installations, the IsaMill was commercialized in 1998 to make the benefits of large scale finer inert grinding available to the wider mining industry for the first time.  The year 2019 marks 25 years since the first commercial installation of the IsaMill and today there are 130 installations totalling over 230MW of installed power.  This paper discusses the development history of the IsaMill at various mine sites, subsequent commercialization, scale up, crossover to coarser gridning and the IsaMill as a technology enabler for the Albion Process.
Keywords: Grinding, Milling, Mineral Processing, Metallurgy, Technology, Innovation, Testing, Scale up
cim.paperattributes.header.paperkeywordsfrench: Grinding, Milling, Mineral Processing, Metallurgy, Technology, Innovation, Testing, Scale up