A process is provided for the preparation of a novel polyaluminum
calcium hydroxychloride composition of enhanced efficiency for
water treatment, paper
sizing, and antiperspirant applications. The polyaluminum
calcium hydroxychloride compositions are prepared via the acidification of higher basicity reaction products to form mid-to-high basicity final products. Two methods are provided for the preparation of higher basicity products, contemplated in the first, and an aqueous acid solution, such as
hydrochloric acid, aluminum
chloride, or a mixture thereof, is mixed with a strong alkaline
calcium salt such as
calcium oxide or
calcium carbonate and aluminum
powder at temperatures greater than 60° C. In a second method,
bauxite,
aluminum hydrate, or
aluminum metal, and calcium
aluminate are mixed with
hydrochloric acid and are reacted at high temperatures and / or elevated pressures for a certain period of time whereby, when the reaction is complete, the mixtures are filtered to obtain clear solutions. The final PAC-Ca solutions may be dried to
powder to have a wide range of basicities from about 40% to about 80%. At lower basicities, the polyaluminum calcium hydroxychloride sales are used preferably as
antiperspirants, while at higher basicities, the solutions are used preferably as
water treatment chemicals.