Issue 37

Q. Like et alii, Frattura ed Integrità Strutturale, 37 (2016) 342-351; DOI: 10.3221/IGF-ESIS.37.45 342 Analysis on the growth of different shapes of mineral microcracks in microwave field Qin Like School of Architecture and Civil Engineering Xi’an University of Science and Technology, Xi’an 710054, P.R China Dai Jun School of Architecture and Civil Engineering Xi’an University of Science and Technology, Xi’an 710054, P.R China A BSTRACT . Microwave heating-assisted ore grinding and crushing can effectively increase the dissociation energy of minerals and decrease energy consumption. Microcrack growth and distribution characteristics inside different shapes of ore particles, which are composed of galena and calcite under microwave irradiation, were analyzed using discrete element method to explore the effects of mineral shapes on microwave-assisted dissociation. Growth laws on the total number of microcracks, numbers of microcracks in galena and calcite, and boundary damage rate against irradiation time under high power and low power were studied. Research results demonstrated that mineral shape mainly affects the quantity of microcracks inside ores but does not their growth law. K EYWORDS . Microwave heating; Ore crushing and grinding; Mesoscale simulation; Microcrack growth; Energy consumption. I NTRODUCTION osts for ore crushing and grinding in dressing plants account for over 40% of the total, and investments for ore crushing and grinding take up for 60% of the total. However, ore crushing and grinding have significantly low energy utilization. Only 1% energy is used for ores to develop new surfaces, and a large amount of energy is lost through heating, noise, and friction [1, 2]. Many improvement methods have been proposed to reduce energy and steel consumptions and increase energy utilization. Among these methods, microwave-assisted technology appears promising [2, 3]. Many gangue minerals in ore (e.g., quartz, calcite, and white mica) are wave transmitting materials, which can be difficult to heat by microwaves. However, unit element ores, most sulfide ores, and oxidized ores (e.g., iron, copper, lead sulfide, pyrite, and manganese oxide ores) absorb materials and can heated in microwave field for a short time [5-7]. Therefore, significant temperature difference and temperature stress are produced between different minerals under microwave irradiation and induce many cracks in minerals [8, 9]. C