Kal Hub urges Goldfields miners to focus on small size fractions

Mining operations in Western Australia’s Goldfields region could add value to their operations by focussing on small size fractions, researchers at Kalgoorlie-Boulder Mining Innovation Hub (Kal Hub) have suggested.

Kal Hub, established in 2018 by the Cooperative Research Centre for Optimising Resource Extraction (CRC ORE), enables focused collaboration between researchers; mining equipment, technology and services suppliers; and mining companies to unlock value for Australian mining through technology development.

Following extensive testing, the Hub’s researchers have explored the use of a preconcentration technique known as ‘grade by size deportment,’ which exploits the tendency for some ores to exhibit breakage leading to concentration of minerals in specific size fractions.

This differs from the technique used in recent decades of mining and processing as much material as possible to exploit economies of scale, leading to bigger equipment, higher throughput plants and greater production.

Kal Hub’s research found that several mine sites in the Goldfields region showed “significant potential” for separation by size, to provide further value to their operations.

This was particularly so at sites that housed either marginal grades or had growing distances from face to surface or mine to mill, subject to increasing transport costs.

CRC ORE chief operating officer doctor Luke Keeney said this work demonstrated the benefits of deploying various aspects of grade engineering – a methodology developed by CRC ORE designed to reject low value material early in the extraction value chain and pre-concentrate processing plant feed.

“This collaboration is good for the Goldfields and for the wider mining industry,” Keeney said. “It demonstrates the benefits mine sites can experience by deploying various aspects of grade engineering, including grade by size deportment.”

Kal Hub technical advisor doctor Laurence Dyer said the objective of the size by deportment project was to complete initial sample testing determining the natural deportment response rankings at a range of deposits.

“A number of companies came on board and we were able to obtain diamond drill core and reverse circulation (RC) drilling samples from a variety of sites in the Goldfields to crush, screen and assay, to develop a snapshot of response to this approach,” Dyer said.

“Gold samples produced varied data with the majority of sites producing low to moderate upgrades on average.

“The RC samples generated greater variation and often decreased in grade at the finest size fractions, likely due to particles being below liberation size, creating issues with the response ranking fit.”

The Hub is continuing to work on a variety of projects throughout the Goldfields that enable optimised resource extraction.

The Hub’s research also showed nickel produced far more consistent behaviour with all sites producing moderate to high responses for both nickel and cobalt. While for some samples the nickel and cobalt response rankings matched well, in others the nickel upgraded significantly better.

These results are explored in greater detail in the whitepaper “Grade deportment by size – initial characterisation of deposits in the Western Australia Goldfields at the small scale,” available on Kal Hub website.

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