Webinar: Application of HIT for Estimating Axb and Bond BWi using Single and Bed Breakage Tests

Since the commercialisation of the HIT device in 2017, the unit has been successfully deployed in metallurgical testing programs globally to help focus early resource definition, progress geometallurgical project development, and provide inputs for mill throughput modelling from SAG feed or blast rejects. As of September 2025, there are 21 units deployed across 14 sites, with over 100,000 tests completed.

The HIT testing protocol has relied to date on access to relatively larger sample fragments, typically 13.2 mm to 22.4 mm for Axb tests and 8.0 to 11.2 mm for Bond BWi tests, requiring 50 to 500 g of sample depending on the ore SG, type of test and size fraction selected. The experience to date indicates excellent agreement with SMC and JKDWT testing when materials tested were similar, and that the Bond Wi normally requires an update to the calibration model to ensure the best accuracy.

The HIT Axb testing has also provided an unbiased assessment of the inherent hardness variability, which can be missed by applying set rock selection protocols. In 2024, an experimental study was initiated at the Brisbane Metallurgical Laboratory in Australia to understand if HIT testing on –2 mm fragments could provide a means to reliably estimate the Axb and Bond BWi from testing material below 2 mm using a modified HIT bed test protocol, called the SFHIT.

The benefit is that the HIT can be deployed on samples finer than 2 mm generated from exploration drilling, offering the potential for targeted exploration drilling and focused geometallurgy sampling and testing/analysis, affording potential cost savings at the front end of a project or resource definition. This paper describes the current standard HIT Axb and Bond BWi measurement and some key learnings from the two tests to date, plus initial findings from the limited application of the SFHIT using 10 g of fragments in the 1.7 × 1.4 mm range.

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