???? ????? ???? ??? ????? ?????????? ?? ???? ??????? metatungstate (AMT) ?? ??? ????? ?? ????????? calcination ??????? ???? ??? ???? ????? ?? ??????? paratungstate (APT), ?? APT ????? ???? ???? ???? ?????? ???? ?? AMT ??? ???? ????? ???? , ????? ??? ???? ????? ??????? metatungstate hydrated ?????? ?????? ????? ?????? ????? metatungstate ??????? ???? ??????.

??????? paratungstate ???? ??? ?????? ???? ??? 180 ~ 260 ℃ ??? ????? AMT, ??????? ?????? ??? ??????:
5(NH₄)₂O?12WO₃?H₂O=3(NH₄)₂O?12WO₃?3H₂O+4NH₃↑

????? ?? ????? ???? ??? ????? ????????? ????????, ?? ????????? ?????? ??? ????? ???? ???? ?? ?????? ???????; ???? ????????? ????? ??? ????? ????? ????? ?? ?????? ???? ?? APT, ??? ???? ????? metatungstate ???????. ??????? ?? ?????? ???????? ??? ?????? ????? ?? ?????? paratungstate ??????? ???? ?? ????? ????? ?? AMT; ?? ???, ??? ?????? ????? ????? ?? ????? ????, ??? ????? ?? ??? ?????? ????? ????? ????? ?????? ???? ?? ?? ??? ????, ??? ???? ?????? ?? ??? ????? ?? ????? ????. ?????, ??????? ?????? ????? (??? ????? ????? ????) ????? ?????? ?? ?????? ???????? ????? ?? ?????? ??????? ?? ??????? paratungstate ??? ??????? metatungstate ???? ?????? ?? ????? ?? AMT.