Aqueous suspension containing silica and aluminum sulfate or alum, process for their preparation and uses of this suspension

摘要

New aq. suspensions of silica and an Al cpd. chosen from the sulphate, basic sulphate, an alum. of a mixt. have a pH less than 4 and a dry material content of 10-50% wt. After standing for 48 hrs. they form gels which are reversible at a low shear rate. Also claimed are their prepn. and use. The prodn. are used in cement compsns., based on cement and water, mortars and concrete, the prepn. of paper pulps, in water treatment and as constituents of mineral glues for paper-cartons and in construction materials. The new prodn., containing precipitated SiO2 and an Al sulphate. They have a tendency to form gels on standing, thus avoiding sedimentation or sepn. on storage. The suspensions are stable for weeks or even months. The gels formed are totally reversible, reverting to a homogeneous suspension, with light stirring, of low viscosity and easy pumpability.