The development of a microwave-assisted laboratory hard rock cutting machine

Mechanical excavators have been widely used for the excavation of rocks in mining and civil engineering projects. The excavation of hard rocks by mechanical machines is difficult due to low advance rate and high tool wear. This difficulty can be overcome by exposing hard rocks to microwave energy just before cutting. This paper presents the newly developed a microwave-assisted laboratory hard rock linear cutting machine. The cutting machine which can be equipped with disc cutter or conical cutter has been integrated with a microwave treatment system. The microwave system is composed of 25 kW-magnetron with a frequency of 915 MHz, wave guide, circulator, water load, stub tuner, and directional coupler. A rock sample is first exposed to microwave energy, then cut by cutter using the test system. During cutting tests, normal and cutting forces are measured, and specific cutting energy values are calculated. A preliminary cutting tests were carried out on some rock types using the cutting machine at different microwave power levels. It was observed that the optimum specific energy values ​​of the samples exposed to microwave energy were considerably lower than those that were not exposed to microwave energy. It was also observed that the optimum specific energy values ​​decreased quite steadily with increasing microwave power. The experiments using the new microwave assisted laboratory hard rock cutting machine showed that microwave treatment of rocks before cutting was an efficient method for the excavation of hard rocks.