Microwaving vermiculite

Vermiculite, a mineral with a sheet-like structure, is mined and then processed into different grades for applications in fireproofing and horticultural markets.

In the process of turning the raw material into a commercially useful material, vermiculite is heated, whereupon it expands. The expansion process, called exfoliation, takes place in commercial furnaces that turn the vermiculite into a low-weight, high-volume product.

Traditionally, however, the gas or oil-fired furnaces have been highly inneficient. And while microwave processing has shown significant promise in reducing energy consumption, a commercial process has never been developed.

Until recently that is. Prof Sam Kingman and his team in the National Centre for Industrial Microwave Processing at Nottingham University have successfully developed a microwave process technology that consumes significantly less energy than traditional techniques.

‘One of vermiculite’s key properties is that it is a poor heat conductor and this leads to extremely high energy consumptions (up to 1Mhh/t) in conventional gas-fired furnaces during the exfoliation process,’  Prof Kingman told The Engineer Online.