GB234885A - Improvements in or relating to the treatment of finely divided coal - Google Patents

Abstract

234,885. Wood, L. A., and Minerals Separation, Ltd. Feb. 29, 1924. Flotation processes. - Finely divided coal is agitated with aeration in aqueous suspension with fine pitch under conditions which lead to the formation of a coal-pitch bearing froth whereby mixed coal and pitch are separated from the bulk of the water and gangue. An aqueous pulp of this mixture is then heated with or without a flocculating agent to flocculate the coal particles which may then be briquetted. In a modification, wherein the coal contains particles too coarse to float, all the coal is subjected to the flotation step and the residues which contain the coarse particles and gangue are treated by gravity concentration to separate the coal and this with the flotation concentrate is subjected to flocculation. In an example, fine anthracite passed through a screen of “inch square aperture is mixed with about 5 per cent of crushed pitch and three times its weight of water and subjected in the presence of a frothing-agent to froth flotation. The residual pulp is treated in an upcast classifier, the outflow from which carrying gangue finer than 40 mesh and coal coarser than 20 mesh is delivered to a 20 mesh shaking screen to retain the coal. The mixture of this coal and the froth is agitated with 2 per cent of tar and creosote oil, steam being introduced to raise the temperature to 80-100‹ C. The hot flocculated pulp is drained on a coco-matting belt, passed through squeezing rollers and briquetted. Specifications 155,875, 185,216, 189,220, 189,221, and 193,947 are referred to.