Size reduction (comminution) is one of the most fundamental processes in mineral processing. The Mineral Processing Laboratory is well equipped with various crushers and tumbling mills and is capable of performing most comminution tasks. The largest jaw crusher will accept feed particles up to 150 mm and the resulting product can be reduced further by subsequent crushers and mills to achieve products in the μm-range. Typical tasks include the production of separation feed, production of material with defined shape, surface area or size distributions and general sample production for external testing and characterization.

Comminution can be performed both wet and dry and at different scales. Several tumbling mills (ball or rod mills) are available including batch ball mills with a 2 kg feed charge to the largest SAG/BM mill with a typical capacity of 100-200 kg/h. The larger tumbling mills or the High Pressure Grinding Rolls (HPGR) are often combined with screens or classifiers to create continuous grinding circuits that feed the pilot scale separation equipment.  Ultrafine grinding can be achieved by using jet mills, stirred mills or, on a small scale, planetary mills. The latter equipment can also be used to study mechanical activation, mechanical alloying or mineral-gas reactions during grinding.

The Mineral Processing Laboratory is also in possession of a SelFrag Lab-unit in which size reduction is achieved by utilizing high voltage pulse fragmentation (HVPF). Compared to mechanical comminution, HVPF can yield unprecedented liberation of the individual components with a minimum of problematic fines.

A selection of the comminution equipment is presented below: