GB459418A - A process for the desulphurisation of gases - Google Patents

Abstract

<PICT:0459418/III/1> Hydrogen sulphide and sulphur dioxide are removed from gases with the production of sulphur by introducing hydrogen sulphide and sulphur dioxide with intense mechanical agitation into a solution of a thiosulphate, whereby the thiosulphate content of the solution is reduced to a predetermined degree and a substantially neutral reaction and the original content of sulphur is maintained in the solution (sulphur being precipitated), and then treating the gases to be freed from sulphur compounds with this activated solution. Under the above conditions, it is stated that sulphur dioxide and thiosulphate react to form an oxide of the thiosulphate, e.g. Na2S2O3.O and sulphur, and this oxide then reacts with hydrogen sulphide to reform thiosulphate and a further quantity of sulphur, no polythionates being formed. In an example of a gas-washing process, gases containing hydrogen sulphide and a thiosulphate solution containing sulphur dioxide are introduced into vessel I, where the solution is activated, and reacts with 90--95 per cent of the hydrogen sulphide. The solution is filtered from sulphur and passed to vessel II together with the untreated hydrogen sulphide, wherein the purification is completed. The solution then passes to vessel III where it is charged with sulphur dioxide and immediately returned to vessel I. The flow of solution from vessel to vessel is arranged to be continuous, only a small amount passing to the second phase. If it is desired only to produce sulphur from hydrogen sulphide, and not completely purify the gases, the three phases may be combined into one. The volume and concentration of the thiosulphate solution are regulated in accordance with the absorption coefficient of hydrogen sulphide and the flow velocity of the gases, and the process may be carried out at raised temperatures. Gases containing sulphur dioxide can be desulphurized if a source of hydrogen sulphide is available. Other compounds such as sulphides, sulphites or polysulphides which are converted into thiosulphate during the reaction may be used. Finely-divided a -sulphur is precipitated, and is readily soluble in carbon disulphide.