Dry comminution and liberation with microwave assistance

This paper presents the experimental results obtained from microwave-assisted comminution/liberation tests on various minerals. The effects of microwave energy intensity and exposure time on microwave heating behaviour and grind-ability of materials are discussed. The experimental results indicated that particle size has a significant effect. The coarser particles ( -9.50 + 4.75 mm) of some minerals (limestone and quartz) were affected by microwave heating to varying degrees, resulting in an increased fineness of the ground product in a subsequent dry ball milling. It was observed that the silicate and carbonate minerals are difficult to heat at lower microwave energy intensities ( <7 kW) during a short expo- sure (< 30 min) due to their principally transparent or reflection to microwave energy. The thermal stress fractures in a copper ore in microwave exposure occurred readily, resulting in a better and cleaner liberation of sulphide minerals from the ore matrix.