The spherical agglomeration process provides an attractive method for the cleaning and recovery of fine coals in the form of compact oil-bonded pellets. In treating a washery effluent containing 50% minus 20 micron material by this technique, the slurry was first mixed under vigorous agitation with oil to deash and dewater the fine coal. The flocculated coal pulp was then formed into larger agglomerates on a modified balling disc. The operation of a semi-pilot scale process is described and an analysis of some of the operating and system variables is given. A semi-theoretical expression to predict the final agglomerate size under various conditions is derived and compared with the experimental data.
Fine Coal Treatment Processes
Most coal cleaning methods depend upon the density difference between coal and its impurities to effect separation. These gravity concentration methods, however, are not practical for particles finer than about 100 mesh and cleaning methods dependent upon the differences in the surface chemistry of coal and foreign matter are used for the finer sizes.
Whereas surface treatment chemicals are used in very small quantities in the flotation of coal, these extremely fine sizes may be removed from suspension only if quite large quantities of oil (5