Floc flotation of Prince coal with simultaneous grinding and hydrophobic flocculation in a Szego mill

A novel idea, combining fine grinding and selective hydrophobic flocculation in a Szego mill, is presented to simplify the hydrophobic flocculation-flotation process for fine coal cleaning. In this simultaneous grinding and hydrophobic flocculation-flotation (SGHFF) process, the excess mechanical energy expended in grinding is utilized for mixing coal slurry, resulting in the formation of hydrophobic coal Aocs in the mill. The SGHFF process was tested for removing ash and pyritic sulfur from Prince coal. After four-stage cleaning flotation, 92.8% of ash and 65.8% of pyrite were rejected from the coal with 81.6% combustible recovery. The size of the Aocs formed in the Szego mill was determined, and the main factors affecting the SGHFF process were also investigated. Compared with the HFF system, the SGHFF system seems economically advantageous, owing to savings in equipment and power consumption. (C) 1997 Elsevier Science Ltd.