GB406343A - Improvements in the production of sulphur from gases containing sulphur dioxide - Google Patents

Abstract

Gases containing sulphur dioxide, especially industrial gases from ore roasting processes containing only small amounts of sulphur dioxide, are treated for the recovery of sulphur by reaction with a solid, liquid or gaseous carbonaceous reducing agent, the resultant gases being passed with a considerable excess of sulphur dioxide over a catalyst to convert the sulphuretted hydrogen, carbon oxysulphide and carbon bisulphide formed during the reduction to sulphur by reaction with the sulphur <PICT:0406343/III/1> dioxide. Preferably glowing coke is used as the reducing agent and where the content of sulphur dioxide is low, this is first concentrated and then reduced. Excess of sulphur dioxide for the catalytic stage may be furnished by passing the gas quickly through the reduction stage but preferably by by-passing some of the concentrated sulphur dioxide before the reduction stage. As shown, waste roaster gases containing 5 per cent of sulphur dioxide are passed by a pipe 8 through an absorber 1 where they are washed with an aqueous sulphur dioxide absorbent, such as is described in Specification 400,998, diluent gases escaping by a pipe 9. The absorbent passes by a pipe 10 to a regenerator 2 heated by steam from a pipe 11, the regenerated absorbent, after cooling, being returned by a pipe 12 to the absorber 1. The expelled sulphur dioxide passes by-pipes 13<a>, 13 to a preheater 3 where it is preheated to 400 DEG C. and thence by a pipe 14 to a coke reducer 4 heated to 1100 DEG C. From the reducer, the gases and vapours are conducted, together with sulphur dioxide by-passed by a pipe 13<b> and valve 7, by a pipe 15 through the heat exchanger 3 to a catalytic chamber 5, maintained at 600 DEG to 800 DEG C, whence they pass to a condenser 6; the catalyst preferred is ferric oxide. So much sulphur dioxide is added that, after leaving the reaction chamber, the content of sulphur dioxide is at least 8 per cent; the gases containing this excess are returned by a pipe 18 to the absorber 1. Specification 20716/13, [Class 90], also is referred to.