Assessing the Response of Tumbling Mills to the Replacement of Balls by Relo Grinding Media (RGM)
27 January, 2020 | White paper
The need for grinding ores at higher tonnages and to finer particle sizes is driven by the increasing cost of energy and the decreasing grade of orebodies. Although grinding circuits can be optimized incrementally, radical changes are required to significantly improve their performance. The Relo grinding media (RGM), which are shaped similarly to “Reuleaux spheroidal tetrahedron”, could be the technological breakthrough that the mineral processing industry is looking for.
Multiple bench-scale comparative grinding tests were conducted to evaluate the benefits of using RGM instead of balls in tumbling mills. The Bond laboratory mill and the locked-cycle test approach were used with comparable grinding media loads (number of media, overall mass, size distribution). Consistently, the energy required to achieve a given product particle size, expressed by the number of mill revolutions needed, was shown to be significantly lower with RGM.
An assessment of the benefits that RGM can provide to a large-scale tumbling mill, operated in closed-circuit and wet-grinding mode, was also made. The test was run at the Rudozem (Pb/Zn) concentrator in Bulgaria where two identical tumbling mills of parallel closed circuits could each be loaded with a different type of grinding media. On average, the throughput (tph) to the RGM-loaded mill circuit was 89% higher than to (almost twice as high as) the ball-loaded mill circuit.
A methodology is currently being developed for predicting the performance of large-scale RGM-loaded tumbling mill from bench-scale test results. The population-balance approach, which involves the determination of the breakage/appearance function in laboratory, is envisaged.
Note that this white paper was written in collaboration with Vassil Genchev, Petar Bodurov and Nikolay Kolev (RELO-B Ltd.) and Donald Leroux from the BBA team. It was the subject of a presentation at the 52nd Canadian Mineral Processors Conference (CMP).
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