Dissolution rate of AlPO
4 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 BaSO
4 powder was carried out under the similar experimental conditions, for comparison. Fractional dissolution was calculated from the analytical result of liberated amounts of PO
43- and SO
42- brought about by the cation exchange reaction.
The results obtained were summarized as follows;
(1) Well-crystallized quartz-type AlPO
4 (b-AlPO
4) did not dissolve appreciably, whereas cristobalite-type AlPO
4 (c-AlPO
4), heat-treated sample of b-AlPO
4, dissolved considerably for its metastability.
(2) Dissolution of AlPO
4 did not so accelerated by suspension concentration as compared with BaSO
4.
(3) Dissolution tendency of both AlPO
4 and BaSO
4 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 BaSO
4. However, the increase in stirring speed hinders the dissolution tendency of AlPO
4 because of slow exchange reaction at the collision interface.
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