A SAG Mill Comminution (SMC) test developed by Dr Steve Morrell looks set to provide a quick and easy method of ore body characterisation by using a cut down version of the well-established and widely-used JKMRC drop weight test.

Dr Morrell said the JKMRC's drop weight test, developed almost ten years ago, has become an industry standard for characterising rock breakage as it provides valuable information about how crushers, autogenous and semi-autogenous mills will work. The problem, as Dr Morrell explained, is the requirement for relatively large quantities of rock to conduct a test.

The SMC test was developed after he recognised there was a need to get information produced by the drop weight tester, but extracted from small pieces of rock. The test uses the drop weight tester on smaller size intervals, cut by a diamond saw from drill core.

"In many cases, mines only have small sections of drill core to send for analysis," Dr Morrell said. "Mines that don't have large quantities of rock to send for a comprehensive assessment of their ore body can now use the SMC test to get A and b values."

"The A and b numbers describe the hardness of the rock," he said. "They are indices of the competence of the rock used in an equation that describes the relationship between size reduction and energy," he said.

The SMC test generates a drop weight index (DWI), which is correlated to the A and b values normally derived from the full drop weight test. The drop weight index also gives a number which says how hard the rock is. Steve Morrell has taken this number and correlated it with the performance of AG and SAG mills.

He said JKTech - the exclusive licensees of the test - offer an SMC testing service which measures the breakage variability in the ore body through 'ore body profiling', thereby enabling predictions of how mill performance will vary as the deposit is mined: "Mines can now get a better picture of the comminution properties of their ore bodies through the use of the SMC test."