Dissolution rate of AlPO₄ powder with different modifications in aqueous suspension containing H-R, strongly acidic H-formed ion exchange resin, was investigated as a function of suspension concentration, temperature and stirring speed. Dissolution of BaSO₄ powder was carried out under the similar experimental conditions, for comparison. Fractional dissolution was calculated from the analytical result of liberated amounts of PO₄^3- and SO₄^2- brought about by the cation exchange reaction.
The results obtained were summarized as follows;
(1) Well-crystallized quartz-type AlPO₄ (b-AlPO₄) did not dissolve appreciably, whereas cristobalite-type AlPO₄ (c-AlPO₄), heat-treated sample of b-AlPO₄, dissolved considerably for its metastability.
(2) Dissolution of AlPO₄ did not so accelerated by suspension concentration as compared with BaSO₄.
(3) Dissolution tendency of both AlPO₄ and BaSO₄ increased with increasing temperature.
(4) Stirring increased the collision frequency between sample powder and H-R particle to enhance the dissolution rate, in general, as shown in BaSO₄. However, the increase in stirring speed hinders the dissolution tendency of AlPO₄ because of slow exchange reaction at the collision interface.