| 摘要 |
780,619. Wet cleaning of asbestos fibres. RAYBESTOS-MANHATTAN, Inc. April 15, 1955, No. 10982/55. Class 82(2) Milled asbestos fibres are cleaned by a froth flotation process in which the fibres and flotation reagents are premixed and introduced into a flotation cell in which the fibres are subjected to turbulence and forced downwardly below the surface of the aqueous fluid in the cell whilst at the same time being propelled forwardly, so that the fibres form a turbulent advancing cloud below the surface level but leaving a relatively quiescent zone beneath the cloud into which the impurities settle by gravity, and then permitting the fibres to rise to the surface at the far end of the cell to be collected. Suitable reagents are dioctyl sodium sulphosuccinate, keryl benzene sulphonate, hexadecyl benzene sulphonate alkyl aryl sulphonate, sodium oleate and ammonium oleate. An apparatus disclosed comprises a premixing tank 10 with agitating means to ensure a homogenous pulp, with a pump 22, pipes 20 and 21, which can if desired be used to aerate the pulp by circulating it through the jet 23, and a flotation tank 16 with paddles 24 for depressing and propelling the pulp whilst impurities settle. Deflecting means 25 are also provided to assist the depression. At the far end of the tank the fibres are allowed to rise and are recovered by a paddle wheel 27. In modifications a series of spitzkasten are formed at the bottom of the tank for evacuation of the impurities, inclined propellers are used for depressing and propelling the pulp, or a series of water jets perform the same service. |
