GB740500A - Improvements in or relating to recovery of metal from aluminous drosses - Google Patents

Abstract

740,500. Recovering aluminium or its alloys from dross. ALUMINUM CO. OF AMERICA. Aug. 20, 1953 [Aug. 30, 1952], No. 22959/53. Class 82 (1). In the recovery of aluminium or aluminium alloy from aluminous dross, freshly skimmed hot dross containing no solid aluminous metal is introduced into a chamber provided with a non-oxidizing atmosphere containing at least 50 per cent aluminium chloride, the dross being agitated whilst its temperature is kept sufficiently high to maintain the aluminium or aluminium alloy in the liquid condition. The agitation may last up to 15 minutes and may be repeated up to 3 times. The non-oxidizing atmosphere may contain an inert gas such as nitrogen or argon, the aluminium chloride being obtained by vaporizing solid chloride before or after introduction into the chamber, or by introducing gaseous chlorine at a rate not exceeding 0.005 pound per minute per pound of dross so as to react with a small proportion of the aluminium or aluminium alloy. The chamber should not be more than 2/3 full of dross, and it may be so constructed, or fitted with a valve or vent, to allow a little aluminium chloride to escape. It may be stationary and contain mechanically operated paddles, or it may comprise a cylinder inclined at 30-60 degrees to the horizontal and rotated at 1-20 r.p.m. In the form shown, the chamber comprises a cylindrical container 2 with a cover 4, a refractory lining 6, a chlorinesupply pipe 12, and a tap-hole 14 for draining off liquid metal 52 from beneath the dross 50. The edge of the cover carries spaced ball-bearing units 10 which bear against a pressure plate 56 attached to a crosshead 58 with flanged lugs 60 to engage under the cover, this assembly being raised and lowered by the piston rod 64 of an air cylinder. The container 2 is carried by a turntable 18, a bearing 20 and the base 34 of a cradle in which it is clamped by a band 54. The cradle is supported on trunnions 36 on a main frame 44, and is tiltable by gearing 38, 40 operated by a crank handle 42 or by power. The vertical members 32 of the cradle carry extensions 66 serving as guides for the crosshead 58. The container 2 carries two tracks 22 for engaging three unequally spaced sets of rollers 24 on shafts 26, one set being driven by a motor and speed-reduction unit 30 to rotate the container when in its inclined position. Specification 370,694 is referred to.