Characterization of strength of Australian iron ores by tumble-drum and drop tests

The nature of fracture and factors that control the extent of fracture in the tumble-drum and drop-tower tests have been identified. The product-size distribution, on which the standard strength indices for these tests are based, and the breakage rate constants depend on a number of factors other than the strength of the lumps. The standard indices and rate constants are meaningful only in a comparative context and for events whose loading mechanism is similar. The results of experiments on three Australian ores, from Yandi, Koolan and Mount Whaleback, are used in combination with fracture mechanics theory to explain why different tumble-drum standards have been found to be fully consistent. A more meaningful measure of strength could be the parameters of the Weibull function, scatter and average strength