GB360142A - A method of manufacturing bronze colours - Google Patents

Abstract

360,142. Ball or tube mills for making bronze colours. HARTSTOFF-METALL AKT.-GES., 39, Kaiser Wilhelm Strasse, C÷penick, Berlin. Sept. 30, 1930, No. 29232. Convention date, Sept. 30, 1929. [Class 59.] Bronze colours in the form of relatively small foils are flattened in ball mills, a gaseous current being passed through the drum of the mill of such a strength that it removes the finished foils and also materially larger unfinished particles, the foils and particles being conveyed by the current to a sifter in which the foils are separated from the particles, the latter being conveyed back to the drum and re-lubricated before, during, or immediately after their re-introduction to the drum. The re-lubrication may be effected by adding the lubricant directly to the returning particles,. or by their contact, with the freshly supplied particles which are lubricated in excess of their normal requirements, or by adding the lubricant to the balls or particles at the inlet end of the drum. As shown, the metal particles are fed from a hopper 1 by a worm 2 and are lubricated by oilers 4, 6 on the way to the ball mill 12, the ends of which are conical and are provided with screens 13, 14 to retain the balls 15. A strong current of gas, e.g. nitrogen, carbonic acid, helium or combustion gases, is passed by the fan 16 through the passages 17, 30, 29, 10 into and through the mill, through the pipe 18 and into a separator 19 having stepped baffles 21 over the edges of which the material passes, the flattened grains being carried upward between the baffles to a cyclone separator 26 from which the foils are deposited in a receptacle 27 whilst the gas is returned by a pipe 28 to the fan 16. The unfinished grains are returned by a rotating blade-valve 31 to the mill, being re-lubricated in the pipe 29 by an oiler 8. The passages 36, 37 in the separator 19 are closable by flaps 32, 33 to regulate the effective sectional area of the sifter and consequently the fineness of the product, this being effected without altering the velocity of the gas through the drum. A filter or filters may be fitted in the return pipe 28. Relubricating oil may be added to the balls by the pipe 11. Specification 204,055, [Class 59, Grinding, crushing, &c.], is referred to.