Research On The Mechanism And Influencing Factors Of Microwave-Assisted Mineral Dissociation Based On Multi-field Coupling

Before smelting,ores and minerals must be ore beneficiated,and most useless materials can be removed before smelting.Currently,the commonly used ore dressing methods all have the disadvantage of low energy utilization rate.Microwave-assisted crushing and dissociation of ores and minerals has received widespread attention as a high-efficiency and energy-saving method.This paper is based on electromagnetic thermal multiphysics coupling,taking pyrite and calcite ore blocks and single-grain minerals as the research object,using a combination of finite element and discrete element methods to carry out the numerical simulation of microwave irradiation,and obtaining different factors through analysis The influence law of microwave irradiation effect,and reveal the dissociation mechanism of microwave irradiation minerals.The main findings of this article are as follows:(1)From a theoretical perspective,explain the basic principles of mineral cracking under microwave irradiation and the necessity of using multi-physics coupling,and write a coupling program to couple the finite element to the discrete element;study the microwave based on the evaluation index of intensity and dissociation rate.The irradiation effect on ore blocks and single-particle minerals;the strength change curve of ore blocks is divided into two stages:rapid reduction and slow reduction.The growth curve of single-particle mineral dissociation rate is divided into three stages:initial growth,rapid growth and slow growth;there is an optimal irradiation time for microwave irradiation of ore blocks and single-particle minerals.When the optimal irradiation time is not reached,the strength of the ore cannot be fully reduced,and the minerals cannot be fully dissociated;if the optimal irradiation time is exceeded,energy will be wasted.(2)Research the dissociation mechanism of microwave-assisted dissociation minerals based on the electric field distribution,temperature distribution,crack distribution and force chain changes of ore minerals under microwave irradiation at different times.The results show that the electric fields of ore blocks and single-particle minerals both gradually increase from top to bottom;the temperature presents a non-uniform mass distribution;the cracks in the ore block develop around the pyrite from bottom to top,and develop between different pyrites.Inter-links are distributed in a mesh pattern.In single-grain minerals,the internal cracks of calcite are distributed radially around the pyrite,and the cracks on the interface are distributed around the pyrite in a ring shape;the crack growth curve with time can be divided into three stages:crack initiation,rapid growth and slow growth;the tensile force exceeds the mineral At the time of strength,tensile cracks are generated,and the internal cracks in the mineral are mainly tensile cracks;the microwave dissociated minerals are divided into three stages:radial crack initiation,radial crack development to the interface,hoop crack initiation and hoop crack development.(3)The simulated ore block is subjected to microwave irradiation under different mineral size,mineral content and microwave power conditions,and the influence of different factors on the irradiation effect of the ore block is discussed.The results show that the larger the mineral size,the smaller the content,and the greater the microwave power,the higher the maximum temperature in the ore block;the crack growth is divided into two stages,the larger the ore size,the more the content,and the greater the microwave power,the number of cracks produced The more;the best irradiation time of 10kW microwave irradiation ore is between 20s-30s,and the ore intensity decreases between 50%-70%after reaching the optimal irradiation time.The size of the mineral does not affect the reduction in intensity.The higher the mineral content and the greater the microwave power,the more obvious the reduction in ore intensity and the higher the energy utilization rate.(4)Simulate microwave irradiation of single-particle minerals under different mineral size,mineral shape and microwave power conditions,and explore the influence of different factors on the irradiation effect of single-particle minerals.The results show that for single-particle minerals,the larger the mineral size and the higher the power,the higher the electric field and temperature in the mineral,and the more cracks will be generated;the shape of the mineral has basically no effect on the electric field,temperature field distribution,and the number of cracks;different factors The growth curve of the lower crack growth curve and the dissociation rate growth curve can be divided into three or two stages of growth;the mineral dissociation rate is about 50%under different factors.The shape of the mineral has little effect on the dissociation rate,and the use of high-power microwave irradiation is more conducive to improving energy utilization efficiency;the optimal irradiation time for mineral dissociation shows a trend of first increasing and then decreasing with the increase of mineral size.The best exposure time is reached first.