BIF型磁铁矿石冲击破碎特性的能量效应

Effects of energy on the impact comminution characteristics of BIF magnetite ore

为研究能量对条带硅铁建造(BIF型)磁铁矿石冲击破碎特性的影响规律,采用导杆式落锤冲击试验系统,对BIF型磁铁矿石进行直接冲击破碎试验,破碎作用更接近机械破碎。结果表明:降低冲击能、理论输入能、应变率或延长作用时间可提高能量效率,破碎动态强度与能量密度呈正比例关系,峰值应变随冲击能密度的增大线性增大,但不受吸收能密度的影响。落锤冲击破碎BIF型磁铁矿石的产品粒度具有分形特性,根据分形理论提出了适合计算产品粒度分形维数的方法,建立了能量与分形维数的关系模型,随着能量密度的增大,分形维数呈负指数函数增长。研究结果为BIF型磁铁矿石破碎能量与粒度控制提供理论依据。

To research the effect of energy on the impact comminution characteristics of BIF magnetite ore, some experiments were done using a drop weight test system with guide rod to make the comminution action closer to mechanical comminution. It is shown that the energy efficiency can be improved by reducing the impact energy, theoretical input energy, and strain rate or extending the impact time. The energy density has positive proportional effect on the comminution dynamic strength. The maximum strain increases with the increase of impact energy density, but it is not related with the absorbed energy density. The product size has fractal characteristic, so an appropriate calculation method for the fractal dimension was put forward by virtue of the fractal theory, the model describing the relation between energy and fractal dimension was established. The fractal dimension increases according to a negative exponential function with the increase of energy density. The research results provide a theoretical basis for the control of comminution energy and particle size of BIF magnetite ore.