INTERACTION BETWEEN PHYSICAL AND CHEMICAL-VARIABLES IN THE FLOTATION OF LOW-RANK COALS

Relatively large amounts of hydrocarbons such as fuel oils are often n eeded in the flotation of low rank coals. The amount of oil can be dec reased considerably by using surfactants as promoters. The reagents th at are good candidates as surfactants to promote hydrophobicity can al so act as emulsifying and wetting agents. Because the physical and che mical variables influence various subprocesses in different ways, thei r influence on the performance parameters is complex. The results of l aboratory tests are presented to show that the dual role of reagents c an be judiciously exploited to increase both the recovery and grade of the clean coal. The mode and order of reagent addition is critical in enhancing their efficacy as flotation promoters. The results demonstr ate the benefits of proper conditioning of the pulp prior to flotation .