Polyaluminumchlorosulfates and preparation and uses thereof

A process for prepartin a high basicity water-soluble polyaluminumchlorosulfate, yielding a content of polymeric aluminum as Al.sub.13 of at least 1 mol % when said polyaluminimchlorosulfate is dissolved in water to form a solution which has an aluminum concentration of 0.01M and having the formula:

• Al(OH).sub.a Cl.sub.b (SO.sub.4).sub.c M.sub.d N.sub.e
• in which:
• M is an alkaline-earth metal;
• N is an alkali metal;
• a, b, c, d and e are numbers such that:
• 1.95<a<2.4;
• 0<c<0.15;
• 0<d<0.16;
• 0.4<e<1.7;
• and a+b+2c=3+2d+e;
• comprising reacting, at a temperature of 50.degree. to 70 .degree. C. an alkaline-earth metal compound M and an alkali metal compound N with a polyaluminumchlorosulfate of the formula:
• Al(OH).sub.a,Cl.sub.b,(SO.sub.4).sub.c,
• in which:
• 1<a'<1.95;
• 0<c'<0.15;
• a'+b'+2c'=3;
• in the following proportion, calculated in molecular equivalents:
• 0<M/Al<0.16 and 0.4<N/Al<1.7.