Verfahren zur Verbesserung der Filtereigenschaften von Asbest

摘要

An asbestos-cement composition contains up to 70%, preferably 10-40%, asbestos fibre which has been treated in air suspension with an atomized spray of Na and/or K silicate solution (see Division C1). Cement, asbestos, and optionally silica, may be present in the proportions 5 : 2 : 3 resp. by weight. The treated asbestos may be dispersed in an aqueous slurry of cement and consolidated, e.g. by transferring the slurry solids on to a revolving element where a laminated composite article is built up.ALSO:The filtration characteristics of asbestos are improved by applying an atomized spray of a sodium and/or potassium silicate solution on an air suspension of asbestos to deposit 0.1 to 4% on the fibre. The solution may contain 3 to 20% silicate having SiO21M2O ratio of 1.6 to 3.75. Asbestos from screw feed regulator 1 is transported on conveyer 2 to fibrizer 3, e.g. a willow. The silicate spray from 5 is directed into the willow feed opening, and coats the fibre, which is then pneumatically conveyed to cyclone separator 6. A moisture content of less than 8% may be ensured by extending this air passage or re-suspending the fibre in a current of air, which may be warm, e.g. at 150 DEG F. This drying step may be omitted when the coated fibre is used to form asbestos-cement articles by dispersing in an aqueous slurry of cement and transferring the slurry solids to a revolving element where a laminated composite article is built up. Treated asbestos or asbestos-cement slurries were shown to have improved rates of filtration (the latter having an asbestos:silica:cement ratio of 2:3:5).ALSO:Asbestos paper is manufactured from asbestos fibre which has been treated in air suspension with an atomized spray of Na and/or K silicate solution (see Division C1), by forming sand sheets with starch or latex binders. Asbestos-cement boards are made by dispersing the treated fibres in an aqueous slurry of cement, collecting and withdrawing a wet layer on a collector roll, transferring it to a revolving accumulator element and building up a laminated composite article.