Preparation of tricalcium phosphate by hydrolysis of dicalcium phosphate with calcium hydroxide

Abstract

A hydrolysis reaction between dicalcium phosphate and calcium hydroxide has been investigated for the formation of tricalcium phosphate. It decreased steadily with the increase in aqueous dicalcium phosphate slurry concentration in the range of 0.5 to 1.25 % under steam pressures of 5-25 Ib/in2 and attained equilibrium at the concentration of 1.25 % aqueous dicalcium phosphate. During the initial period of 2 h, the hydrolysis proceeded gradually to the respective maximums at the steam pressures of 15 and 25 Ib/in2 and thereupon it was constant. It was also shown that 28.33 ?( excess above the stoichiometric quantity of the hydrolysing agent, calcium hydroxidc, was necessary for the complete hydrolysis to occur at the steam pressure of 25 Ib/in2 for the aqueous suspensions of 5 and 25 % dicalcium phosphate. The effect of increasing steam pressure showed that a complete conversion of dicalcium phosphate to tricalcium phosphate could be obtained at a steam pressure of 51.5 Ib/in2 for any concentration of aqueous phosphate slurry.