Improvements in or relating to the pelleting of finely divided solid substances

摘要

654,272. Making pellets from finely-divided solids. MONSANTO CHEMICAL CO. Feb. 25, 1948, No. 5595. Convention date, July 19, 1943. [Class 87 (ii)] Pellets of phthalic anhydride, ferric sulphate, aluminium sulphate or sodium sulphate are formed by placing a mass of the substance, in a finely-divided state, in a drum 10, rotating the drum, and continuously supplying, through a pipe 18, additional finely-divided solids and either a substance which is a liquid, e.g. water, an aqueous solution of the substance or the substance in a molten state, or a substance which is solid but which melts on heating to react with the finely-divided solids into the mass of the substance below the surface of the mass. The liquid is preferably fed into a sparsely-filled region A, Fig. 2, caused by the rotation of the drum. By adjusting the amount of liquid and additional finely-divided material added to the drum, the material in the region A is kept relatively plastic. The temperature of the material may also be controlled by cooling or heating the drum, and cooling or heating the additional finely-divided solid material. The additional material is supplied by transferring pellets from the drum 10 to screens 25, 26 by screw conveyers 20, 21 and then feeding the fines through a pipe 30, and some of the pellets, after being ground in a grinder 28, through pipe 29, back to the drum by a conveyer 17. The drum may be inclined to increase the capacity of the drum and to remove selectively from the drum, the larger pellets. The pellets may be cooled, heated or dried after formation. Specification 654,246 is referred to. The Specification as open to inspection under Sect. 91 comprises also carrying out the process without the addition of finely-divided solids, by continuously supplying only hot molten liquid. This subject-matter does not appear in the Specification as accepted.