| abstract |
Gas contg. sulphur cpds. is freed from the sulphur cpds. by absorption with aq. alkali contg. Ca(OH)2 or NaOH in the form of a suspension or soln., part or all of the adsorbent liquid being recycled, in a process in which the concn. of S2- ions in the absorbent is kept =2 pref. =1/l, and the concn. of alkali is not 0.02 N (0.03N) so as to stabilise absorption of hydrosulphuric acid even at temps. >60 degrees C without sensible loss of gaseous H2S. Method is esp. for treating off gases produced in the granulation of blast furnace slag to prevent air pollution by removal of H2S, SO2, etc.) for treatment of off gases from the Krans process and from hydrodesulphurisation of hydrocarbon oils. |