Process for production of sulfur from so.sub.2 -containing gas

Abstract

A process for production of sulfur from SO.sub.2 -containing gas is disclosed comprising the steps of contacting said SO.sub.2 -containing gas mixed with additional oxygen or air, with carbonaceous materials, in a SO.sub.2 reduction reactor under elevated temperatures to thereby produce a first gaseous mixture containing vaporous sulfur, H.sub.2 S, COS and unreacted SO.sub.2 ; separating said vaporous sulfur by condensation from the first gaseous mixture to thereby obtain a second gaseous mixture; introducing the second gaseous mixture into a Claus reactor to thereby obtain a third gaseous mixture containing a vaporous sulfur produced by Claus reaction; separating said vaporous sulfur by condensation from the third gaseous mixture to thereby obtain a fourth gaseous mixture of reduced sulfur compound content; and recovering the sulfur separated from said first and third gaseous mixtures, the improvement comprising regulating the amount of oxygen or air mixed with the SO.sub.2 -containing gas feed so that (a) the SO.sub.2 conversion in said SO.sub.2 reduction reactor may be controlled at a predetermined value in the range of 75-85% or (b) the SO.sub.2 concentration of said fourth gaseous mixture may be controlled at a predetermined value, whereby the molar ratio of H.sub.2 S/SO.sub.2 or (H.sub.2 S+COS)/SO.sub.2 of said second gaseous mixture is maintained at a level of about 2.