The index A*b, determined from JKM RC DWT results, has become well known in the mining industry as a reliable measure of ore hardness in impact or crushing, having the inferred units of tonnes/kWh. This index evolved from a long history of comminution studies at the JKMRC, including the development of the now superseded JKTech twin-pendulum, the industry-standard JK Drop Weight Tester (JKDWT) and the faster alternative JKMRC Rotary Breakage Tester (JKRBT). A reduced version of the DWT, the SMC Test®, also provides estimates of the A*b though the testing of only one particle size at five specific energies.
Experimental determination of A*b using the above devices/tests requires samples, with sufficient mass, to be sent to designated laboratories, registered to conduct such tests.

This protocol is fine for bankable and commercial testing, where material characterization data is used in conjunction with machine specific data in modelling and simulation, and power-based calculations. However, for comparative testing, where results are required at the time of sampling (e.g. for plant troubleshooting or spot-surveys), or for rapid ranking of geometallurgical samples, these existing tests simply do not provide a timely, viable and cost-effective solution.

In order to address this critical void in the realm of comparative testing, a new device has been developed, exploiting a central feature of single particle impact testing – that the A*b can be reliably estimated using one precise low energy test, and that the Bond grindability can be linked to the breakage response at one precise high energy test. Called the Hardness Index Tester (or HIT), this patented device has been precision engineered to allow users to break narrowly sized fragments at a set specific energy in a safe and easy manner. The manufacturing materials have been chosen carefully to ensure compatibility with the intended use and portability to any site, whilst minimizing cost.

The device is supplied with a novel QA/QC feature, to ensure that the targeted potential energy is consistently delivered. The product from the HIT breakage test can be quickly sized using a single screen to determine the mass percent undersize, from which the A*b index is calculated directly at site – eliminating the need to send the raw data offsite for analysis.