采用颗粒流软件建立了基质为方解石、内含方铅矿颗粒的方铅矿二维模型,研究了脉冲微波功率密度、重复频率、脉宽、辐照时间对方铅矿微裂纹发育的影响.结果表明:由微波诱导产生的微裂纹集中在方铅矿和方解石的晶粒边界,并随辐照时间的增长呈发散状向周围扩展延伸,微裂纹类型以张性裂纹为主,剪切裂纹占极少比例;在输入能量相同的情况下,微波功率密度和辐照时间对矿石颗粒的损伤程度及微裂纹的发育有重大影响,高功率密度和短辐照时间比低功率密度和长辐照时间更有利于矿石颗粒内部微裂纹的发育;在一定范围内提高重复频率、增大脉宽有助于提高矿石颗粒内部微裂纹的发育程度及增大矿石颗粒的损伤程度,这有利于后续磨矿的进行;在其他条件一定的情况下,辐照时间并不是越长越好,选定最佳的最短辐照时间对于降低矿石的力学强度及减少能耗有重大意义.
Particle flow code software was used to establish a two-dimensional model with calcite as matrix and consisting galena inside.The effects of power density,pulse repetition frequency,pulse width and exposure time of microwave irradiation on the development of micro cracks of galena ore were investigated.The results showed that the thermally-induced micro cracks generated mainly along the grain boundaries,most of the cracks were radially oriented tensile cracks originating from the absorbent phase boundary,and the number of shear cracks was far less than the number of tensile cracks.Under the condition of same microwave energy input,the extent of damage and the crack pattern in the ore depended strongly on the applied power and irradiation time.High applied power density and short irradiation time were helpful to the development of micro cracks.Both the damage of an ore particle and the development degree of micro cracks inside an ore particle increased with the increase of repetition frequency and the pulse width within a certain range,which was helpful to the grinding process.The irradiation time had an optimal length,which had significant meaning for decreasing the mechanical strength of the ore particles and reducing the energy consumption.
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