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

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.