Experimental study of dry permanent magnet magnetic separation of high-sulfur fine coal

Dry magnetic separation of high-sulfur fine coal was carried out using a novel permanent magnet high-gradient magnetic separator (HGMS). The samples were analyzed using a vibrating sample magnetometer (VSM) and X-ray diffractometer (XRD) to determine the properties of the different size fractions of pulverized coal. It was found that magnetic susceptibility and the ash and sulfur content increased with increasing particle size below 0.9mm; Sulfur reduction of 44% and ash reduction of 43% were obtained from coal with particle size of 0.15~0.074 mm, while the clean coal yield reached 95.61%. The results show that desulfurization efficiency and de-ashing efficiency decreased with increasing size of the pulverized fine coal from 53% to 37% and from 49% to 32%, respectively. Desulfurization efficiency and de-ashing efficiency of fine coal were significantly improved by permanent magnet dry magnetic separation using a new permanent magnet HGMS. However, decreases in desulfurization efficiency and de-ashing efficiency of the different size coal samples were found to correlate with reduced clean coal recovery, besides coal fraction sized at 0.0-0.074 mm.