Simultaneous removal of SO 2 , SO 3 and H 2 SO 4 mist from the gas after TiO 2 calcining

Absorption of SO 2 and SO 3 in the solutions of waste ferrous sulfate (so‐called ‘green salt’) and in the spent acid after TiO 2 hydrolysis, at H 2 SO 4 concentrations ranging from 0–5 to 15 g/m 3 (STP), was studied. The rate of SO 3 absorption has been found to rise linearly with increasing SO 3 concentration in the gas and to be independent on H 2 SO 4 concentration in solution. The SO 2 absorption also rises linearly with increasing SO 2 content in the gas, but diminishes as H 2 SO 4 concentration increases—an upper limit of 100 g H 2 SO 4 /kg H 2 O is indicated. The initial concentration of the solution must not be higher than 40 g H 2 SO 4 /kg H 2 O.