The coal-derived pyrite sample used in the present investigation was extracted from the Qinshui coalfield, Shanxi province of China. The initial sample of the coal-derived pyrite with particle size 0.1–0.2 mm was first subjected to gravity separation to remove the inclusions of coal using a laboratory mechanical pan (Micropaner).
Then, the obtained concentrate was cleaned by means of magnetic separation. The purity of the final product was estimated by X-ray diffraction (XRD). The XRD pattern for the coal-derived pyrite is presented in Fig. 1.
2.2.1. X-