The assessment of the factors affecting the microwave heating of magmatic rocks


KAHRAMAN S., Canpolat A. N. , FENER M., Kilic C. O.

GEOMECHANICS AND GEOPHYSICS FOR GEO-ENERGY AND GEO-RESOURCES, vol.6, no.4, 2020 (SCI-Expanded) identifier identifier

Abstract

Low cutting rate and high tool wear are the important problems during excavating hard rocks. In order to find a solution for these problems, some investigations have been carried out by several researchers. One of the recent studies is the microwave assisted excavation of hard rocks. Revealing the impacts of microwave exposure on the minerals and micro-structures of rocks will be useful for the investigations on the microwave assisted hard rock excavation. In this research, the factors affecting the microwave heating of magmatic rocks were studied. First, the mineralogical analysis was carried out using the thin sections of the untreated specimens. Then, the specimens were exposed to microwaves at different power levels for varying durations. The surface temperature of the specimens was also measured using the infrared gun. After that, the mineralogical analysis was repeated for the treated specimens. The evaluation of the results shows that increasing microwave energy and radiation duration increases the surface temperatures of the tested specimens. The own mineral percentages of a specific specimen are the key factor for the heating degree. It was seen that the micro-structural changes in the specimens began at about the surface temperature of 100 degrees C. Very important micro-structural changes were observed in the specimens with metallic minerals and the minerals having metallic elements. It is concluded that the applied microwave power, the treatment time, and the mineral constitutes importantly influence the heating degrees of magmatic rocks irradiated with the microwave energy. The developed empirical equation can be used for the prediction of surface temperatures of the magmatic rocks using the percentages of quartz plus feldspar, the density and the porosity.