GB1242055A - Improvements relating to a method of fluidizing aggregate material - Google Patents

Abstract

1,242,055. Pneumatic separation. FAWKHAM DEVELOPMENTS Ltd. 6 Sept., 1968 [12 July, 1967], No. 32132/67. Heading B2H. [Also in Division F4] An apparatus for fluidizing aggregate material having a surface moisture content, e.g. small coals, quarried stones or mineral ores, in order to separate dust and small granular particles therefrom, comprises a fluidizing chamber 2, Fig. I, having means, e.g. perforations 4, in its bottom wall for the introduction of fluidizing air so as to create a fluidized bed 12 of material in the lower part of the chamber, the air being at a temperature insufficient to separate the dust and small granular particles, and means, e.g. jets 14, for introducing heated air into the chamber above the bed 12 so as to maintain such temperature and humidity above the bed as to separate and dry the dust and small granular particles. The fluidizing air, which may be at or above ambient temperature or which may be saturated at the temperature of the bed by the addition of steam or the recirculation of part of the air leaving the apparatus, is introduced via an inlet 9 and a wind box 3 through the perforated wall 4. The material is fed down a chute 5, the coarse material being discharged at 6 and the dust and small particles at 7 to a duct 8 connected to a cyclone, baffle chamber, filter or scrubber. The jets 14 are provided in one or more walls of the apparatus and direct the air either horizontally or downwardly towards the upper surface of the fluidized bed 12. Agitators 10 assist in maintaining the bed in its fluidized state. In a modification, Fig. 3 (not shown), instead of a perforated bottom wall 4 and agitators 10, spaced apart elliptical rods (15), alternate ones of which have their major axes at right angles, are provided at the bottom of the chamber 2 and are rotatable in the same direction and at the same speed. In a further modification, the hot air jets 14 are omitted and heated air is introduced into the chamber 2 together with the aggregate material either directly into the chute 5 or, as shown in Fig. 2, through an inlet 18 in a subsidiary wind box 17 formed below slats or louvres 16 which constitute the floor of a modified chute 5.