Influence of grinding methods on the preparation of ultra-clean coal from slime

This study discusses the technology of coal slime recovery for preparing ultra-clean coal (UCC). X-ray diffraction analysis (XRD) and scanning electron microscopy combined with energy dispersive spectroscopy (SEM-EDS) were used to analyze the characteristics of coal slime and to explore the types of minerals and embedded characteristics of coal slime. The particle interaction energy and contact angle analysis were used to determine the UCC preparation process through dry and wet grinding dissociation comparison and shear flocculation flotation tests, combined with zeta potential measurements. The results showed that the inorganic minerals in the slime were mainly kaolinite clay minerals, which were easy to mud in the pulp and needed grinding. The calculation results of the interaction energy indicated that the interaction force of dry-ground slime in the pulp was small, and flocculation was more likely to occur. The wet-ground product was subjected to three flotations to obtain UCC with an ash content of 0.95%.