Calcium vanadate was prepared by adding
calcium chloride solution to the sodium vanadate
leach liquor maintained at 90°C. Depending
on the amount of calcium chloride added
and the pH of the solution it was possible to precipitate
either 2 CaO. V205 or 4Ca0. V205. The
former was usually obtained from the neutral
solution (pH 7) whereas the latter from a highly
alkaline solution of pH 12. Vanadium recovery
as calcium vanadate corresponded to about 99
pct when the amount of calcium chloride used
was about 50 pct excess over stoichiometric requirements. The precipitation reaction could
be presented as