An invitation by Glencore Technology to an IsaMill workshop at Comminution '25

The need to grind ever finer, as ores have become more complex and of lower grade, has led to the successful adoption of stirred mills. The most successful of these has been the IsaMill, which has led the way in energy efficient ultra-fine grinding since its development in the early 1990s.

IsaMill

In the 6th edition of my book Mineral Processing Technology I highlighted, in the Introduction, the inability to treat the huge zinc-lead- silver deposit at McArthur River in Australia. Discovered in 1955, for 35 years it resisted attempts to find an economic processing route and it ranked as one of the world's largest undeveloped deposits, with reserves estimated at 227 million tonnes, Due to the extremely fine dissemination and intergrowth of the minerals, attempts to treat the ore by existing processing methods had proved fruitless. 

The 6th edition was published in 1997 so I must have written this section shortly after the publication of the 5th edition in 1992, because in 1995 the McArthur River mine commenced production, the concentrator producing a bulk lead-zinc concentrate with an extremely fine product size of 80% minus 7 microns.

Development of a circuit for McArthur River ore recommenced in August 1989 at Mount Isa under the direction of Bill Johnson, the Milling Research Manager (posting of 27 August 2020). The ore was even more difficult to treat than the Mount Isa zinc-lead ore, well known for its difficult properties; one important outcome of the McArthur River project was the IsaMill, developed from the stirred milling technology of Netzsch Feinmahltechnik GmbH.

The mill was successfully introduced at  Mount Isa Mines and the Lead/Zinc Concentrator manager at that time was Joe Pease, who said that the team delivered the first significant breakthrough in fine grinding in 50 years, and the most significant development since SAG milling. The work at Mount Isa led to the development of the fine grinding necessary for mineral liberation of the McArthur River ore.

Joe Pease and Bill Johnson in Denver for their induction into
International Mining Hall of Fame in 2017

Mechanical Engineer Peter Woodall played a very important role in the pilot plant phase, the design modification phase and in numerous later activities with the mill and in 2008 Bill and Peter shared the Mineral Industry Operating Technique Award, for the development of the IsaMill technology.

The IsaMill technology, which is marketed by Glencore Technology, has spread into other duties in mineral processing and larger models have been developed, resulting in a large number operating in industry. The benefits of fine grinding in the IsaMill are now being applied at increasingly coarser grind sizes, and to a diverse range of minerals, a remarkable transition from the original small-scale applications. Larger ceramic media is now pushing the boundaries of feed size and can offer advantages in grinding efficiencies, product size distribution and internal wear.

Prior to Comminution '23, conference sponsor Glencore Technology held an afternoon workshop on the IsaMill at the Vineyard Hotel, attended by around 40 delegates.

Glencore workshop at Comminution '23

To celebrate the 30th Anniversary of the IsaMill, Glencore Technology invite Comminution '25 delegates to an exclusive workshop "Expanding the capability and application of the IsaMill" on Sunday 30 March immediately prior to the Comminution '25 welcoming reception. In the 2 hour workshop the Glencore Technology team will lead interactive sessions to help delegates make the right choices for their unique processing needs. Full details can be found on the workshop flyer.

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