Effect of Microwave Irradiation on Mechanical Properties and Microstructures of Minerals

Abstract

Microwave-assisted rock breaking is a new and promising technology for the tunneling and drilling industry. Minerals in rocks have an important influence on the effect of microwave-assisted rock breaking. In this paper, common minerals in rocks such as potash feldspar (hereafter referred to as K-feldspar), calcite and pyroxene were selected as samples, and a lot of microwave irradiation tests were carried out by using a hamilab-v1500 microwave oven. The mass, strength and microstructure of the rock samples were tested before and after microwave irradiation. The change law of the mineral mass, strength and microstructure with regard to temperature was analyzed, and the influence mechanism was discussed. The results show that the strength of K-feldspar increases from 20 °C to 400 °C but decreases significantly when it is higher than 400 °C; the strength of pyroxene increases from 20 °C to 600 °C but decreases when it is higher than 600 °C; the strength of calcite decreases with the increase in temperature. As for the weakening pattern, pyroxene shows drawstring, step and flow with the increase in temperature, but K-feldspar and calcite show that failure occurs along the cleavage plane of the crystal structure. The higher the temperature of microwave irradiation, the finer the pattern at the fractured zone is, and the more fragmented it becomes; the loss of mineral mass increases with the increase in the temperature of microwave irradiation.