GB814182A - Improvements in the dry dust freeing of coals and like materials - Google Patents

Abstract

814,182. Pneumatic separators. HARVENGT, E. Feb. 3, 1956 [Feb. 3, 1955], No. 3528/56. Class 117 A process for the dry dust freeing of wet materials, e.g. coals, comprises, together with a treatment phase during which the materials are heated by a current of hot gases, a subsequent treatment phase effected in the presence of gaseous current flowing in the direction of travel of the materials, wherein the whole or part of the sensible heat acquired by the materials during the heating phase is used to increase the drying thereof and thus enable the dust therein to be freed and removed therefrom by the said gaseous current, thereby permitting their dust freeing to be completed to the desired degree. Wet coal to be freed from dust passes from a hopper 3 Fig. 1 and is spread by adjustable baffles 9 and is acted upon by hot gases flowing upwardly through a conduit 2 from a heat source 1 and a passage 7. Fines pass to an expansion chamber 10 and the remainder flows through a passage 21 to a second conduit 16 where it is further refined by hot gases supplied from a passage 17 and flowing upwardly therethrough. The less fine material drawn into the chamber 10 falls into a hopper 11 and is led through passage 22 to the conduit 16. Dust particles are drawn from the chamber 10 and conduit 16 and flow through conduit 13 to a cyclone 14 connected through 15 to a suction fan. Coarser particles drawn through conduit 13 flow into a chamber 23 and conduit 24, and pass either to an outlet 26 or to the conduit 16 at 26a. Coarse products from the conduit 16 flow from a discharge passage 19 into a rotary tube 27 where a drying and a further seperation takes place, and the coal is delivered to an outlet 29. The tube outlet 35 is connected to a cyclone 37 which is connected to a suction fan 38, and warm or hot gases are drawn through the tube from an inlet 33 and carry away fine particles to the cyclone. Relatively coarse particles fall into a hopper 43. Baffles 139 Fig. 2 extend into the tube 27 and lift the material in the manner shown. In a modified construction of the tube, the baffles extending from its periphery are radial, and additional radial baffles extend from the rotary axis of the tube. Alternatively the baffles have a helical formation. In order to control the gas flow through the tube a diaphragm 39, Fig. 4, perforated at 40, is associated with a by-pass conduit 41 with an adjusting member 42. In the embodiment of Fig. 5 the rotary chamber or tube 27 is arranged between the passage 21 leading from the conduit 2, and the conduit 16, so that the discharge of coarse grains from the tube is led to the conduit 16. The gas outlet 35 of the tube leads to an expansion chamber 43 connected via a cyclone 37 to a suction fan 38, and the less fine particles from the chamber 43, together with those from the expansion chamber 10 flow through passage 43a to the conduit 16. Alternatively the coarse particles from the chamber 10 are fed to the inlet of the tube 27. Conduit 16 forms part of a closed circuit with a cyclone 14, and a conduit 15 with a suction fan 15a. An exhaust outlet 15b is arranged in the circuit. Specification 690,400 is referred to.