Effect of multi-intensification on the liberation of maceral components in coal

Abstract In order to achieve high-quality coal resources in western China, this study focused on a coal sample from the Shangwan Coal Mine, owned by the China Shendong Group, and employed scanning electron microscopy (SEM), mineral liberation analysis (MLA), and maceral component quantitative analysis for investigating the coal sample’s liberation characteristics and crack distribution patterns after pre-grading and microwave processing. The results show that the physical properties of coal maceral components significantly affected the related enrichment performances, and many intra-group and inter-group cracks were produced under the induction of microwave radiation. The cracks then developed and stopped growing among the different maceral components and mineral components, thereby inducing selective and random pulverization along the crack growth direction in further pulverization process and effectively enhancing the liberation properties of different components. Using the Sandbox method, the fractal dimension of the cracks on the particle surface was calculated to be 1.01, which confirmed the self-similarity of the cracks on the coal surface. Multi-intensification maceral liberation also yielded favorable grading performances. The inertinite content was the highest (75.23%) in grade-3 product, while the vitrinite content was the highest (66.3%) in grade-1 product; the corresponding enrichment ratios were 2.15 and 1.59, respectively. Moreover, the ash content in grade-2 product was the lowest, which dropped by 3.61% compared with that in raw coal sample.