Abstract
A series of impact compression tests were conducted to study the breakage characteristics of magnetite, as well as the impact pressure on its strain rate and dynamic compressive strength. The dynamic mechanical properties and fragmentation size distribution of magnetite under diverse impact loads and cyclic impact were investigated, with fractal theory as a basis and split Hopkinson pressure bar (SHPB). Breakage methods were also employed to analyze the fracture morphology of magnetite. According to the result, the fractal dimension can reflect the distribution of fragments in various sizes. If the strain rate increases, the fractal dimension will be larger, the fragment size will be finer, and the fragmentation degree will be more influential. A micro-analysis of SEM images demonstrates that the fracture morphology is determined by mineral properties. Under low load cyclic impact, intergranular fracture is the main fractography. Besides, the intergranular fracture will be changed to a transgranular one as the impact load increases.
Highlights
Minerals breakage, which is indispensable for the mining industry, helps mineral liberation and subsequent separation [1]
The speed of impact of the warhead was obtained by the electronic counter, and the dynamic strain was obtained by the data acquisition device
It can be seen that the incident energy achieved by the incident rod is proportional impact pressure
Summary
Minerals breakage, which is indispensable for the mining industry, helps mineral liberation and subsequent separation [1] It has bearings on the breaking performance of the mechanical and beneficiation process [2]. Studies on the dynamic mechanical characteristics of magnetite under low energy repeated impacts are rare [13]. Strain rate is an essential mechanical parameter for the dynamic fragmentation of rocks, which was conducted mainly under a low strain rate This means that the impact load at a high strain rate has been less commonly studied. This paper studies the dynamic mechanical, fragmentation size distribution and fracture morphology characteristics of magnetite under high- and low-load cyclic impact. The crushing system of magnetite may be under various impact forces, which results in a high energy consumption and low efficiency. This study is important in both theory and practice because it guides engineering practice, reducing unnecessary energy consumption, but it helps the understanding of magnetite dynamics
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