Quite a few studies have been carried out that look at the application of microwave energy for material processing in various spheres. Microwaves can selectively and quickly heat the target bulk material thanks to its dielectric properties. Gold ores have a complex mineral composition and the effect of microwaves is different on different minerals. This enables to heat selected areas of the rock causing a strong thermal stress. This leads to microcracks occurring at the mineral boundaries resulting in weaker grains and hence better grinding performance. Refractory gold concentrates contain a lot of sulphides, which get hot instantly when exposed to microwave radiation. Thus, microwave energy can be efficiently used to roast sulphide gold concentrates. During microwave roasting, heat conversion takes place directly in the sulphides and the reaction starts immediately. That’s why microwave roasting is a much faster process compared with convection roasting. This paper provides a brief overview of microwave energy used for gold ore and concentrate processing and describes the behaviour of minerals in the microwave field, as well as the results of a number of studies that looked at using microwave energy to destroy rocks, roast refractory sulphide gold concentrates and regenerate charcoals. The key advantages of microwave radiation include an easy process control, the possibility to quickly and selectively heat the product and low energy costs.
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