SIMULTANEOUS REMOVAL OF SO2 AND H2S FROM EXHAUST GASES.

摘要

Simultaneous removal of SO2 and H2S from waste gas is carried out by contacting the gas in countercurrent with a first suspension (I) in stage 1 and the second and third suspensions (II) and (III) in stage 2. (I) and (III) each comprise 40-60 vol.% of the suspension accrusing in the sump of stage 2 and contain 60-95 g/l ZnSO3, 60-90 g/l ZnO and 0.1-10 g/l ZnS and are recycled continuously to the top of stages 1 and 2 respectively. The suspension contg. 20-35 g/l ZnS, 130-145 g/l ZnSO4 and 0.1-8 g/l ZnSO3, accrusing in the sump of stage 1, is also recycled continuously to the top of stage 1. (II) contains 80-150 g/l ZnO. The purified gas is discharged at the top of stage 2. Pref. stage 1 and/or 2 is carried out in a scrubber and stage 2 pref. is above stage 1 in a sepg. column. Pt. of the suspension from the sump of stage 1 is removed and adjusted to pH 0.6-1.0 with 48-97% H2SO4 or adjusted to pH 1.3-1.8 with Cl2.