Magnetic separation and thermo-magneto-chemical properties of coal liquefaction mineral participates

Sulphide solid particulates have been successfully separated from solvent-refined coal (SRC) liquid streams by high-gradient magnetic separation (HGMS) preceded by a sulphidation pretreatment in an H₂S-rich gaseous atmosphere. This pretreatment is derived from studies of the properties of dry sulphide residual liquefaction solids, treated in an atmosphere of various H₂/H₂S compositions. Procedures have been devised for promoting rapid conversion of the weakly magnetic hexagonal pyrrhotites to the more strongly magnetic monoclinic form at a temperature intermediate to those of the SRC dissolver and the magnetic separation stage.