Optimization of Microwave Presplitting Iron Ore to Improve Mechanical Mining Efficiency.

Optimizing the microwave parameters adopted in microwave-assisted mechanical mining is of great significance to improving the efficiency of the deep resource development. The effects of varying the type of microwave antenna, microwave power, and working distance on the reflection coefficient and heating characteristics of Sishanling iron ore were studied. The optimized microwave operating parameters were proposed, and microwave irradiation and mechanical cutting tests were then carried out on the ore samples under true triaxial stress conditions to verify the feasibility of the optimized parameters. The results show that the ore's reflection coefficient increased at first and then decreased as the working distance (2–8 cm) was increased. The reflection coefficient increased as the microwave power was increased. Compared with other distances, the temperature and temperature gradient of the irradiated surfaces of samples were maximized when the working distance was 2 cm. The optimum microwave parameters of iron ore were: a microwave antenna format of horn antenna/standard waveguide antenna, a working distance of 2 cm. Under true triaxial stress conditions, samples suffered no macroscopic damage when irradiated for 300 s at a working distance of 8 cm. When the working distance was reduced to 2 cm, however, samples broke apart after just 10 s (failure mainly taking the form of intermittent spalling). Arcing readily occurred under true triaxial stress conditions when the working distance was 2 cm. This phenomenon occurred on the irradiated surface of the sample and the baffle of the antenna could also be ignited. Ways of optimizing the antenna were put forward and discussed. Highlights: The influence of microwave antenna type, microwave power and working distance on reflection coefficient and heating characteristics of Sishanling iron ore was studied. The influence of optimized working distance on microwave cracking effect of ore under true triaxial stress was studied. The optimization scheme of microwave antenna was proposed based on the arc phenomenon of ore. [ABSTRACT FROM AUTHOR]