GB988700A - - Google Patents

Abstract

<PICT:0988700/C1/1> Fibrous bundles of crude asbestos separated from the source rock are opened up by mixing the bundles with a liquid and feeding the mixture through between rubbing surfaces, the method being characterized in that over a long path formed by the rubbing surfaces and extending helically or according to a spiral space curve and having a length amounting to a multiple of the greatest fibre length, the fibre-liquid mixture is forced through between the rubbing surfaces with controllable high hydraulic pressure so that the fibres are fulled or squeezed in constantly varying directions by being continually bent transversely of their longitudinal extension. Preferably the fibre-liquid mixture is fed in one or more passes through the same opening-up apparatus or through different such apparatus connected in series. To shorten the opening-up period, a friction increasing substance, e.g. sand, finely ground quartz, finely ground asbestos blende, cement or a mixture of several of these, may be added to the fibre-liquid mixture. The entire quantity of cement required for making asbestos cement finished products may be added at this stage, also pigments may be added. In Fig. 5 a conical housing 31 with a rigid inner working surface provided with depressions 31c and a conical working body 271 on a mechanically driven shaft are so arranged that between the inner working surface and the working body there is a narrow cone-shaped passage 58 through which the fibre-liquid mixture is passed from pipe conduit 12. The working body, which is confined between plates 46 and 47 and consists of a plurality of annular discs 27a of rubber or resilient synthetic material, is held in position by helical pressure spring 56. In Fig. 1 a horizontal housing 1 has a rotatable rigid shaft 5 which may have one or several ribs 27 and said shaft is surrounded by an inflatable rubber lining 18 of annular cross-section and a <PICT:0988700/C1/2> packet of annular discs consisting of alternately arranged rubber discs 20 that fit closely around shaft 5 and rigid annular discs 21 having a bore diameter such that annular spaces 22 are formed between the discs and the shaft. The fibre-liquid mixture passes between shaft 5 and body 18 and then it is forced alternately through annular slits between rubber discs 20 and shaft 5, and the annular spaces 22.