Effects of Minerals Type and Content on the Synthetic Graphitization of Coal: Insights from the Mixture of Minerals and Anthracite with Varied Rank

The challenge of how to effectively treat minerals in coal before synthetic graphitization is a practical problem. It is unrealistic to remove minerals completely via physical or chemical methods. So, it is essential to clarify the role of minerals in the synthetic graphitization of coal. Based on the complex mineral composition, the mixture samples consisting of coal and mineral are used to obtain the effect of minerals type and content on the synthetic graphitization of coal. The role of minerals in synthetic graphitization is closely associated with the mineral content and type, as well as the rank. As to the lower-rank anthracite, quartz, kaolinite, and calcite have the role of inhibitor for the yields and defect degrees of corresponding samples after synthetic graphitization derived from the mixtures, but the role of catalyzer for their crystal structure (the degree of graphitization, stacking height, lateral size). The increasing content of quartz, kaolinite, and calcite is harmful for the yield, but useful for the crystal structure and defect degrees: the increasing content of pyrite is harmful for the yield, degree of graphitization, and stacking height, and it is useful for defect degrees. As to the higher-rank anthracite, quartz, kaolinite, and calcite have the role of inhibitor for the yield of corresponding samples after synthetic graphitization, catalyzer for their crystal sizes (stacking height, lateral size), and inertia for their degrees of graphitization. The increasing content of quartz, kaolinite, calcite, and pyrite is harmful for the yield and crystal size. A lower coal rank indicates being more prone to positive mineral effects on synthetic graphitization. The role of minerals in the synthetic graphitization of coal is complex and also represents a coupling relationship with the thermal transformation of anthracite.