The mill that changed fine grinding: Glencore Technology’s IsaMill™ turns 30

Brisbane, Australia

For immediate release

Thirty years after transforming fine grinding in mineral processing, the IsaMill continues to evolve, helping operations around the world improve energy efficiency, increase throughput and unlock greater value from their ore bodies.

Originally developed through a partnership between Mount Isa Mines and NETZSCH to solve a complex metallurgical challenge, the IsaMill has become one of the mining industry's most successful grinding technologies. Since its introduction in 1994, it has been installed at 157 metalliferous operations across 23 countries, helping sites improve recovery while reducing energy consumption and operating costs.

The IsaMill was born from necessity. During the 1980s, declining ore quality at Mount Isa Mines created the need for much finer grinding to unlock mineral value. Existing technologies struggled to achieve the required grind size efficiently, prompting engineers to look beyond the mining industry for a solution. Working with German ultrafine milling specialist NETZSCH, the team developed the IsaMill, a technology that ultimately increased zinc recovery by 16 per cent while maintaining concentrate grade.

While the IsaMill established itself as a breakthrough in fine and ultrafine grinding, continuous improvement has remained central to its development. Over the past three decades, Glencore Technology has expanded the IsaMill platform from the original M3000 design to larger configurations capable of processing significantly higher throughputs, including the 5.5MW M20,000 mill and designs up to the M50,000 scale.

Advancements have extended well beyond mill size. Successive generations of IsaMill designs have focused on reducing capital costs, simplifying installation and improving operating efficiency. Plant layouts have been optimised to lower overall project costs, with low-profile configurations reducing structural steel and concrete requirements and cutting installation costs by around 30 per cent.

Recent developments in internal component design are also delivering significant performance gains. Technologies such as square spacers and protruding discs have improved grinding efficiency through enhanced media movement and energy transfer. Testing and commercial trials have demonstrated energy efficiency improvements exceeding 20 per cent, with some applications achieving substantially higher gains.

These advancements are helping operations process more material, reduce energy consumption and maximise the value of existing infrastructure, outcomes that are becoming increasingly important as ore bodies become more complex and sustainability expectations continue to rise.

“The IsaMill has always been about finding smarter ways to grind more efficiently,” said Ion Gurnett, Principal Metallurgist at Glencore Technology.

“While mill size has increased over the years, some of the most exciting gains are now coming from improvements to mill internals and circuit design. We're seeing small design changes deliver meaningful improvements in energy efficiency and throughput, helping customers get more from their existing infrastructure while keeping costs under control.”

Further insights into the IsaMill's 30-year journey and the future of stirred milling technology will be shared in the paper Stirring the Pot: 30 Years of Innovation and Beyond, presented by Ion Gurnett at IMPC 2026 in Cape Town, South Africa, on Wednesday 21 October.
 

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