Acta Montanistica Slovaca (Sep 2000)
The influence of microwave radiation on the failure of rocks
Abstract
The heating and processing of materials using microwaves becomes increasingly popular for industrial applications. Compared to conventional heating, microwave processing can provide a rapid, the production of materials with unique properties, and reductions in manufacturing costs and processing times.The positive influence of the microwave radiation on the faulting of the individual rocks is described. At the heating of the heterogeneous ores, the microwaves have an selective effect for individual mineral components. Owing to the different degree of to heating and thermal dilatation the stress and destructive attendants arise, which increase the faulting of rocks. The rate of the faulting has been investigated on the basis of measurement of the elastic waves motion velocity by the impulse-dynamic method.On the basis of the measured values of elastic wave motion in the observed rocks before and after their microwave heating the coefficient of faulting was computed according to the relation (1). Subsequently, from these coefficients the rate of faulting was determined for individual rocks according to Jaeger (Table 1).Various rate of rocks faulting caused by the radiation depend on their ability to absorb microwave power. High rate of faulting was observed in rocks with strong absorption of microwave power unlike from substances which weakly absorb the radiation. Particularly, a high rate of faulting after microwave heating was observed at samples of limestone (Roòava-Jovice) and magnesite (Haèava). Low rate of faulting was obtained in the case of granodiorite (Podhradová), granite (Hnilec), sandstone (Horelica), marble (Koelga) and andesite (Huboovce).The influence of microwave energy on the rate of rocks faulting was confirmed. The new knowledge can be applied for the intensification of the rock disintegration processes.
