???? ??????? ????????

p> ??????? ??????? ???? ????? ???? ???? ????? ?????. CaWO 4 , ?? scheelite, ???? ????? ?? HCl ????? ????? ????????, ??? decomposes ??? WO3 ???? ?????????? ??????.
CaWO4 + 2HCl → CaCl2 + H2WO4
H2WO4 + heat → H2O + WO3
??? ??? ????? ????? WO 3 ??? ?? ??? calcination ?? ??????? paratungstate (APT) ?????? ?????:
(NH4)10[H2W12O42]?4H2O → 12 WO3 + 10NH3 + 10H2O




