GB683037A - Improvements in and relating to methods and apparatus for introducing lubricant into powdered materials - Google Patents

Abstract

683,037. Mixing appliances. BRITISH THOMSON-HOUSTON CO., Ltd. June 19, 1950 [June 29, 1949], No. 15272/50. Class 86 A method of introducing a lubricant into a powdered material consists in interfusing a stream of fine particles of the lubricant with a stream of the powdered material, the stream of lubricant being formed with the aid of an inert pressure gas which also serves to maintain a protective atmosphere at the point where the two streams interfuse with each other. The invention more particularly relates to the introduction of a pressing lubricant into refractory carbide metal powders. As described a stream of pre-mixed carbide powdered ingredients from a barrel 1 is delivered by a vibrating hopper 3 and vibrating shoot 4 into a mixing chamber 7. The lubricant is maintained at or above its melting point in a heated container 8, and carbon dioxide at a pressure of one-half to three pounds per square inch is introduced into the container 8 through the line 13 to force the melted lubricant along a heated pipe 11 to a spray nozzle 12. Carbon dioxide under pressure of twenty to fifty pounds per square inch is supplied to the nozzle 12 through line 15 to produce an atomized spray of fine particles of lubricant which is sprayed on to the stream of powdered ingredients. The carbide powder having lubricant sprayed thereon immediately falls into a hammer mill 22 for intimate mixing of the lubricant with the powdered ingredients, the resultant mixture subsequently falling into a receiving barrel 23. In order to synchronize the initial flow of both powder and lubricant a vane 18, displaceable by powder flowing from the shoot 4, is arranged to operate a mercury switch in the circuit of a solenoid valve 17 in the pipe 11. In order to maintain a closed system in which the powdered carbide mixture and the lubricant are housed and maintained in an inert carbon dioxide atmosphere, the barrel 1 is connected to hopper 3 by a rubber bellows 26 and the hammer mill 22 is connected to the receiving barrel 23 by rubber bellows 27. The proportions of the mixture are controllable by valves 14 and 16 in the carbon dioxide supply lines and by a rheostat 6 in the circuit of the vibrating mechanism of the shoot 4, the rates of feed by weight being indicated by means of scales 10 and 25 which carry the containers 8 and 23 respectively.