GB837539A - Improvements relating to the pneumatic refining of metals - Google Patents

Abstract

837,539. Mixing solids with gases. ARBED ACIERIES REUNIES DE BURBACH-EICH-DUDELANGE S.A. Jan. 5, 1959 [Jan. 13, 1958; Oct. 1, 1958; Oct. 22, 1958], No. 332/59. Class 86 In apparatus for putting powders or granules into suspension in a flowing gaseous medium for injection into, or on to, a metallic melt, a variable speed rotor constitutes a metering device and is arranged in the passage leading from a supply container for the powder and a main duct conveying the gaseous medium. In Fig. 2, the apparatus comprises a powder container 1, a pocketed cylindrical metering-rotor 4 driven by a motor 5, and the main gas line 10. The motor 5 may be a variable speed motor, or a constant speed motor with a variable gear drive to the rotor. The rate of supply of powder to the duct is indicated by a revolution counter, and the rate may also be indicated by the readings of gauges 6 which show the weight of powder in the container 1. The flow of powder to the. duct, and jamming is prevented, by bypassing some of the gas flow to various parts of the apparatus, e.g. the part 2 leading to the rotor may be lined with perforated plates which are blown with gas from the conduit 10; gas is supplied to the top of the container 1 from the duct 10 through a pipe 8 to force the powder downwardly, the supply of gas to the mixing point 9 being throttled by a valve 11 to produce in the container 1, and elsewhere when desired, a pressure greater than that at the point 9 where the pressure may be further lowered by the employment of a Venturi nozzle. The tapered connection 15 between the rotor 4 and the duct 10 may be provided with perforated plates or tubes supplied with gas through pipe 18 to prevent jamming, and the valve 19 is adjusted to conform with the output of the metering device 4. A constriction may be placed in the pipe 10 downstream of 9 to prevent jamming if it is necessary suddenly to shut off the gas flow. To prevent jamming of, the rotor by material getting into small clearances between the end faces of the rotor and its casing, the clearances are increased by providing bosses 8<SP>b</SP> on the end faces of the casing 5<SP>a</SP> and blowing gas into the clearances at 14<SP>a</SP>. The bosses 8<SP>b</SP> may be extended upwardly in segmental form, or a further protuberance in arcuate form may be provided on each end face 5<SP>a</SP>, adjacent the upper peripheral part of the rotor. The pockets of the rotor may be cleared by blowing gas through the central shaft into the pockets through holes or porous insets whilst they are in discharging position or continuously, or a pipe may direct gas upwardly from beneath the rotor into the pockets. Fig. 7 shows means, for preventing powder from entering the rotor bearing, comprising a ring 23 having a concave inner surface against which gas is directed from a passage 24, or the gas may be supplied through a passage 25. In Fig. 8, entry of powder is prevented by graphite rings 31 which are pressed by springs 32 against the casing bosses, and gas is directed against the rings from channels 33