Patent GB-190802719-A (GB)
Title: Improvements in the Treatment of Sulphur-dioxide and Sulphuretted Hydrogen for the Obtainment of Sulphur therefrom.
Inventor: FELD WALTHER
Filed: 1908-02-06
Granted: 1908-09-24
Abstract: 2719. Feld, W. March 6, 1907, [date applied for under Section 91 of Patents &c. Act, 1907]. Sulphur is obtained according to the known reaction : 2 H2S + SO2 = 3 S + 2 H2O, by passing the gases through one or more liquids which dissolve sulphur, for example the so-called tar-oils obtained by the distillation of organic matter and consisting of mixtures of hydrocarbons. The reaction is less rapid with pure solvents than with crude tar-oils, and is accelerated when there is present a substance which combines with sulphur dioxide or hydrogen sulphide to form compounds which again become decomposed when heated with liquids. The following are examples of such accelerating - substances : the organic nitrogenous substances present in the crude oils, aromatic amines, amides, nitriles, thioamides, &c., alipbatic compounds which are basic or weakly acid or not, other organic bodies having the aforesaid property, such as oils distilled from ordinary or brown coal, scale, peat, bones, &c, which contain pyridine bases, inorganic ammonium bases, for example S Cl2NH3, CaCl2 8 NH3, and Cu2Cl2 2 NH3, basic ani sulphurous compounds of aluminium, and basic ammonium and magnesium compounds and their sulphites, such as MgO, MgCO3 (N H4)2CO3, MgSO3, and (NH4)2SO3. With the last mentioned series of compounds, the reaction liquid must be kept acid as by the presence of a slight excess of sulphur dioxide or of slightly acid substances, for example phenols. The transformation of the basic accelerating-bodies into salts of fixed oxy-acids of sulphur, such as sulphates, due to the presence of sulphur trioxide &c. in the sulphur dioxide, destroys their activity ; according'y one or more substances, capable of again resolving these bodies, is added to the reaction liquid either before or after the removal of the sulphur, for example oxides, hydrates, carbonates, sulpbides, and sulphites of the alkalis, alkaline earths, ammonium, magnesium, and aluminium. If the gases to be deprived of hydrogen sulphide contain ammonia, it is not necessary to add another regenerating-substance. In this case, a reaction liquid consisting of a fraction of the tar distillation rich in phenols is preferable. Carbolic acid may be used as the reaction liquid, tar bases being added. Ammonia may be passed through the liquid either with the sulphur dioxide and hydrogen sulphide or alternately with them. In an example, the dioxide and sulphide are parsed through heavy tar-oil, containing the greater part of the nitrogenous tarbases, heated to 40‹ C. The oil may contain added tar-bases and a regenerating-substance, for example sodium carbonate. There should be at least one molecular quantity of the dioxide for each two of the sulphide. The liquid may be first saturated with the dioxide and the sulphide then introduced, and so on, alternately, until the sulphur crystallizes out. When sufficient sulphur has been formed, the liquid is allowed to cool and the sulphur crystallizes out together with the sodium sulphate and sulphite formed. It is then centrifuged and treated with steam to remove the adhering oil, which is recovered upon condensation, and to dissolve the sodium compounds in the condensation water. Alternatively, instead of adding the sodium salt to the reaction liquid before starting, the mother liquor from the sulphur, after admixture with the liquor recovered from the steam, is treated with milk of lime. Insoluble gypsum separates, while the regenerated tar-bases are dissolved in the oil.