| abstract |
Disclosed herein are processes for oxidising Sn 2+ dissolved in an aqueous solution to stannic compounds using NO 2 and optionally O 2 as oxidants, wherein the aqueous solution is kept at a pH in the range of 0 to 7, wherein a salt Sn 2+ (X n- ) 2/n and the oxidants are used according to the reaction scheme a Sn 2+ (X n- ) 2/n + b O 2 + c NO 2 -→ stannic compounds in which scheme a, b and c are mole numbers; with the proviso that when b is essentially zero, then the aqueous solution is essentially free of C1 - , HSO 4 n - and SO 4 2 - . |