基于矿物特征分析的磁铁矿动态破碎与能耗机制

Dynamic Crushing and Energy Consumption Mechanism of Magnetite Based on Mineral Characterization Analysis

为研究动载下磁铁矿石的破碎特性及能耗规律,以某沉积变质型磁铁矿石为研究对象,利用分离式霍普金森压杆对磁铁矿石进行冲击破碎试验,结合矿物特征理论分析磁铁矿石的动力学特性、破碎能耗及破碎形态。结果表明:在冲击载荷作用下,磁铁矿石应力-应变曲线呈现3个阶段:弹性阶段、裂纹演化阶段、卸载阶段。随着入射能的增加,破碎能耗及能耗密度不断增大,破碎平均粒径随着能耗密度的增加而减小。在低入射能下,能量以弹性能形式储存在石英颗粒内部,当应力波作用结束后,能量释放,用于原有裂隙扩展,破坏试样内部结构。在高入射能下,石英颗粒储存弹性能速率加快,更快达到储存极限,内部能量快速释放,原有裂隙快速扩展并产生大量的沿晶裂隙及穿晶裂隙,试样内部结构破坏严重。磁铁矿石成分以石英为主,矿石结构构造和接触关系简单,结构以结晶结构、交代结构为主,构造以条带构造、块状构造为主,矿物颗粒之间成线接触,破碎主要以沿晶破裂和穿晶破裂为主,带有阶梯状和蛇纹状破裂形态。

In order to study the crushing characteristics and energy consumption law of magnetite under dynamic load,a sedimentary metamorphic magnetite was taken as the research object,and the impact crushing test of magnetite was carried out by using a separated Hopkinson pressure bar.The dynamic characteristics,crushing energy consumption and crushing morphology of the magnetite were analyzed based on the theory of mineral characteristics.The results show that the stress-strain curve of magnetite presents three stages under impact load:elastic stage,crack evolution stage and unloading stage.With the increase of incident energy,the crushing energy consumption and energy consumption density increase continuously,and the crushing average diameter decreases with the increase of energy consumption density.Under low incident energy,the energy is stored in the form of elastic energy inside the quartz particles,and when the stress wave action is over,the energy is released for the expansion of the original cracks,destroying the internal structure of the specimen.Under high incident energy,the rate of storing elastic energy in quartz particles is accelerated,reaching the storage limit faster,and the internal energy is released rapidly.The original fissures are expanded rapidly and a large number of along-crystal fissures and through-crystal fissures are generated,and the internal structure of the specimen is seriously damaged.The composition of magnetite is mainly quartz.The structural,construction and contact relationship of the ore are simple.The structure is mainly crystalline structure and metasomatic structure.The construction is mainly strip construction and block construction.The mineral particles are in linear contact,and the crushing is mainly along-crystal rupture and through-crystal rupture,with stepped and serpentine rupture morphology.