Microwave Technology for Mineral Grinding
Reduce the energy demand for grinding minerals.
Vast amounts of energy are used every year (3-5% of the world’s total electrical energy use) in the mining and minerals processing industries to grind mined rocks and ores in preparation for subsequent processing and metal extraction. Currently, the mining industry uses crushers and grinding mills to break and then liberate individual minerals. Once liberated, the minerals can be recovered and concentrated. Typically, only 1% of the energy input is used to create new surfaces, the rest becoming noise and heat.
Prior to mechanically grinding the material, microwaves can be used to selectively heat parts of the rock, causing them to fracture along grain boundaries. Using numerical modelling and computer simulations, the ability to heat minerals differentially was shown to be key – hence the application of low amounts of focussed microwave energy.
A specifically designed microwave cavity based on the modelling has produced a step change in the development of the technology by taking electromagnetic design principles and integrating them with process engineering. The energy-saving technique has already attracted interest from some of the key players in the mining industry, including Rio Tinto, which has supported the research since 1995 and plans to use the technology, if scale-up tests prove successful.