Abstract: Disclosed herein are various types of systems and methods for the efficient production of sulfur from a sulfur-laden gas. The system described herein includes a desulfurization unit, a regenerator receiving sulfurized mass from the desulfurization unit, a sulfur recovery unit, a sulfur track in fluid communication with the regenerator and the sulfur recovery unit, and a sulfur concentrator on a sulfur track. The sulfur stream coming out of the regenerator is concentrated using the sulfur concentrator and converted into a sulfur product at the sulfur recovery unit.

Abstract: The present invention is directed to a method for purifying a high-temperature reducing gas by continuously circulating the processes of reducing a regenerated absorbent with the high-temperature reducing gas, until concentrations of aimed reducing gases have become uniform on upstream and downstream sides of the absorbent, and absorbing sulfur compounds by the use of this absorbent and thereby removing these sulfur compounds therefrom; the aforesaid method being characterized by using at least three reactors filled with the absorbent, by consisting of the four steps of reduction, absorption, SO.sub.2 reduction and regeneration, and by comprising the steps of feeding a circulating gas from the regenerating step to the SO.sub.2 reducing step; converting an SO.sub.2 gas produced in the regenerating step and the SO.sub.2 reducing step into elemental sulfur and recovering the latter as liquid sulfur; and introducing a part of the SO.sub.2 gas into the reducing step and returning the remaining SO.sub.

Abstract: The present invention relates to a method for removing sulphur dioxide and possible hydrogen sulphide as well as nitric oxides from exhaust gases by means of sulphides in a liquid phase so that the sulphur is recovered in the form of molten elemental sulphur. The soluble sulphates formed in the scrubbing are regenerated after a known fashion by means of sulphides or by reducing back into sulphides and are conducted back into the sulphur dioxide absorption stage.

Abstract: The invention relates to a method for cleaning exhaust gases weak in sulphur dioxide, or sulphur dioxide and hydrogen sulphide. In order to remove the sulphur content of an exhaust gas, the exhaust gas is absorbed into a solution containing sulphide. Thereafter into the solution is added an agent which causes any unstable compounds of sulphur and oxygen, such as thiosulphate and polythionates, which are formed in the scrubbing solution, to decompose into elemental sulphur and sulphate in the autoclave whereinto the scrubbing solution is fed. The pH of the solution emerging from the autoclave is adjusted to stay within the range 2.0-2.9.

Abstract: Thiosalts contained in waste streams are oxidized to sulfate ions in the presence of sulfur-bound copper. Air oxidation of the waste stream is effected in a slurry of the copper compound, which may be CuS, Cu.sub.2 S or chalcopyrite, and continuous long term operation is possible without loss of catalytic activity and without catalyst degradation.

Abstract: The process for recovering recyclable sulphur from a strongly colored solution obtained from the production of sulphur dyestuffs containing alkali metal sulfides, alkali metal polysulfides, sulphur dyestuffs or mixtures thereof comprising(a) mixing said solution at an alkaline pH with a decolorizing amount of an iron or zinc compound which is a hydroxide or the salt of an inorganic acid whereby a precipitate is formed,(b) separating the precipitate to isolate a decolorized solution, and either(c) precipitating elemental sulphur from the decolorized solution by adding sulphur dioxide or alkali metal thiosulfate under acidic conditions, and(d) separating the precipitated elemental sulphur, or(e) recycling the decolorized solution for use in the manufacture of sulphur dyestuffs.

Abstract: A method for the removal of carbon or carbon compounds from a waste stream generated in an unsupported slurry catalyst process utilized for the hydroconversion of heavy hydrocarbonaceous black oil which stream comprises vanadium sulfide, nickel sulfide and carbon or carbon compounds is disclosed. The carbon or carbon compound is removed by contacting the waste stream with sulfur dioxide at oxidizing conditions to yield a solid residue which contains metal sulfides.

Abstract: The process for recovering recyclable elemental sulfur from a strongly colored solution containing alkali metal sulfides, alkali metal polysulfides, or mixtures thereof comprising(a) mixing said solution at an alkaline pH with a decolorizing amount of an iron or zinc compound which is a hydroxide or the salt of an inorganic acid whereby a precipitate is formed,(b) separating the precipitate to isolate a decolorized solution,(c) precipitating elemental sulfur from the decolorized solution by adding sulfur dioxide or alkali metal thiosulfate under acidic conditions, and(d) separating the precipitated elemental sulfur.

Abstract: The invention provides a cyclic process for recovering copper from sulfide ores containing copper and iron which comprises reacting the sulfide ore with sulfur dioxide gas at a temperature of at least about 500.degree. C. to form elemental sulfur, removing the elemental sulfur, reacting the residual solids with concentrated sulfuric acid at a temperature of about 180.degree. to 500.degree. C. to form copper sulfate and sulfur dioxide gas, recycling the sulfur dioxide gas for reaction with additional ore, roasting the remaining solids at a temperature of about 400.degree. C. to 900.degree. C., leaching the roasted solids with an aqueous solution to solubilize the copper sulfate and recovering copper from the solubilized copper sulfate. In another embodiment of the invention, the roasting step is eliminated by removing magnetite from the solids remaining after removal of the elemental sulfur.

Abstract: Hydrogen sulfide-containing waste gases whose complete treatment is indispensable from the viewpoint of environmental pollution problem, are purified in two steps consisting of a first step in which the gases are absorbed in an aqueous solution of sodium hydroxide or/and sodium sulfide, and a second step in which sulfuric acid and sulfur dioxide gas are simultaneously introduced into the resulting solution after absorption to deposit sulfur. Further, for recovery of the resulting sulfur, a particular apparatus is provided.