Abstract: There is provided a method for the removal of arsenic from an arsenical bearing sulfides ore, comprising a thermal treatment of arsenical sulfide in the presence of sulfur dioxide, yielding a calcine and a sublimate, the sublimate containing arsenious oxide. The method allows recovering metallic value from an arsenic-bearing metallic sulfides ore, by recovery of the calcine comprising the metallic value of the ore.

Abstract: SO3 is formed from a replenished circulating inventory of fresh and recycled SO2. Also, a feed stream of replenished SO2 is heated by indirect heat exchange with a hot stream of SO2 and SO3 whereby the hot stream is cooled for separating the two gases. The heated feed stream of replenished SO2 serves as a hot gaseous feed to a sulfur burner. This SO2 feed is divided into two feed streams, one being oxygenated with pure oxygen and the other remains as an SO2 feed. These feeds plus a feed of molten sulfur are concurrently and separately introduced into the sulfur burner where additional SO2 is formed via continuous exothermic reaction. Although heated, the oxygenated feed(s) of SO2 bring in the needed oxygen for the reaction and the feeds of the oxygenated and non-oxygenated SO2 serve as a heat sink in the sulfur burner to reduce the temperature therein.

Abstract: A method of producing sulfur dioxide is provided. A feed gas stream comprising at least 5% by volume hydrogen sulfide is provided. The feed gas stream is separated into a hydrogen sulfide stream and a hydrocarbon gas stream. An oxidant stream is provided and is combusted with the hydrogen sulfide stream to produce thermal power and a combustion stream containing sulfur dioxide and steam. Sulfur dioxide is separated from the combustion stream.

Abstract: A hybrid sulfur (HyS) cycle process for the production of hydrogen is provided. The process uses a proton exchange membrane (PEM) SO2-depolarized electrolyzer (SDE) for the low-temperature, electrochemical reaction step and a bayonet reactor for the high-temperature decomposition step The process can be operated at lower temperature and pressure ranges while still providing an overall energy efficient cycle process.

Abstract: A process for making molecular hydrogen, elemental sulfur and sulfur dioxide from hydrogen sulfide. The process involves contacting a gas stream of hydrogen sulfide within a contacting zone with a contacting composition comprising metal sulfide in a lower sulfided state and yielding from the contacting zone a product gas stream comprising hydrogen and a recovered contacting composition comprising metal sulfide in a higher sulfided state. The higher metal sulfide is regenerated with oxygen to yield elemental sulfur and sulfur dioxide.

Abstract: The present invention relates to a process and a device for the combustion of sulphur and/or sulphur-containing compounds, via which a sufficient production of SO2-containing gases having a high SO2 concentration is made possible. The combustion preferably proceeds using a combustion gas which has an oxygen fraction at least as high as air, but preferably a higher fraction of oxygen. The process and the device should be suitable, in particular, for providing sulphur dioxide as a source for further production of sulphuric acid or highly concentrated SO3-containing gases. In addition, the device and the process should be suitable for oxidizing hydrogen-sulphide-containing gases, such as occur, for example, in the refinery industry, in high concentrations to SO2.

Abstract: A method of producing sulfur dioxide is provided. A feed gas stream comprising at least 5% by volume hydrogen sulfide is provided. The feed gas stream is separated into a hydrogen sulfide stream and a hydrocarbon gas stream. An oxidant stream is provided and is combusted with the hydrogen sulfide stream to produce thermal power and a combustion stream containing sulfur dioxide and steam. Sulfur dioxide is separated from the combustion stream.

Abstract: With a method configured to generate process gas that contains hydrogen sulfide and sulfur dioxide for the Claus process, hydrogen-sulfide containing feed gas is burned with pure oxygen by means of several burners opening out into a combustion chamber wherein the pure oxygen is fed into the combustion chamber through a central tube each, the feed gas through a tube arranged coaxially around the central tube and inert gas as purge gas via an annular duct coaxially surrounding the feed gas tube. A favorable option of the method consists in the use of CO2 reclaimed by desorption of laden methanol as purge gas.

Abstract: A method and apparatus for processing a sour gas rich in carbon dioxide in a Claus process, so sulfur compounds are removed by a selective solvent in a gas scrubbing process. Sulfur components and carbon dioxide, are separated into at least two sour gas fractions, wherein at least one sour gas fraction having a higher content of sulfur components is obtained, wherein the fraction having the highest hydrogen sulfide content is introduced in the thermal reaction stage of the Claus furnace with a gas containing oxygen by means of a burner. The sulfur is converted to sulfur dioxide in the thermal reaction stage of the Claus furnace and exhaust gases are discharged into the closed Claus reaction chamber behind the burner. The remaining sour gas fractions stripped of sulfur components are fed to the Claus reaction chamber and are mixed with the combustion gases leaving the burner.

Abstract: The present invention relates to a process and a device for the combustion of sulphur and/or sulphur-containing compounds, with formation of sulphur dioxide.

Abstract: Methods and systems for generating sulfuric acid are disclosed. In some embodiments, the method includes combusting a sulfur-containing material with a gas including oxygen to produce a first stream of sulfur dioxide, mixing water with the first stream of sulfur dioxide to produce a mixed stream, using an energy, electrolytically converting the mixed stream of sulfur dioxide and water into sulfuric acid and hydrogen, generating a source of energy from the hydrogen, and providing the source of energy as at least a portion of the energy for electrolytically converting the first stream of sulfur dioxide and water into sulfuric acid and hydrogen. In some embodiments, the system includes a first chamber for combusting a sulfur-containing material to produce a first stream of sulfur dioxide, an electrolytic cell for converting the first stream into sulfuric acid and hydrogen, and a fuel cell for generating an energy source from the hydrogen.

Abstract: A process for treating a gas stream comprising H2S that includes the step of selectively oxidizing the H2S of the gas stream within a catalytic zone containing an oxidation catalyst and in the presence of an inert liquid medium and molecular oxygen to form elemental sulfur and a gas stream depleted of H2S. A liquid stream yielded from the catalytic zone and containing the inert liquid medium and liquid elemental sulfur undergoes a separation into a first liquid phase rich in the inert liquid medium and a second liquid phase rich in elemental sulfur. Either at least a part of the liquid stream or at least a part of the second liquid phase, or both, undergoes a combustion to form a fluid stream that comprises sulfur dioxide.

Abstract: Methods and systems for generating sulfuric acid (102) are disclosed. In some embodiments, the method includes combusting a sulfur-containing material (114) with a gas including oxygen (116) to produce a first stream of sulfur dioxide (118), mixing water with the first stream of sulfur dioxide to produce a mixed stream, using an energy, electrolytically converting (108) the mixed stream of sulfur dioxide and water into sulfuric acid (102) and hydrogen (122), generating a source of energy (126) from the hydrogen, and providing the source of energy as at least a portion of the energy for electrolytically converting the first stream of sulfur dioxide and water into sulfuric acid and hydrogen. In some embodiments, the system includes a first chamber for combusting a sulfur-containing material to produce a first stream of sulfur dioxide, an electrolytic cell (108) for converting the first stream into sulfuric acid and hydrogen, and a fuel cell (112) for generating an energy source from the hydrogen.

Abstract: The present invention relates to a method for separation and recycling of pure sulfur dioxide from a gaseous mixture in the IS cycle. More specifically, the present invention relates to a method for separation and recycling of pure sulfur dioxide from a gaseous mixture in the IS cycle using an ionic liquid under a specific condition. When compared with the conventional amine-based absorbent, the use of the ionic liquid enables continuous absorption and stripping of SO2 even at high temperature, and enables a reversible absorption of SO2 without loss, decomposition or degradation of a solvent due to good chemical stability, thereby enabling separation and recycling of pure SO2 from a gaseous mixture in the IS cycle.

Abstract: A process for treating a gas stream comprising H2S that includes the step of selectively oxidizing the H2S of the gas stream within a catalytic zone containing an oxidation catalyst and in the presence of an inert liquid medium and molecular oxygen to form elemental sulfur and a gas stream depleted of H2S. A liquid stream yielded from the catalytic zone and containing the inert liquid medium and liquid elemental sulfur undergoes a separation into a first liquid phase rich in the inert liquid medium and a second liquid phase rich in elemental sulfur. Either at least a part of the liquid stream or at least a part of the second liquid phase, or both, undergoes a combustion to form a fluid stream that comprises sulfur dioxide.

Abstract: The invention provides a process for disposal of mercaptans, the process comprising the steps of: (a) contacting a feed gas stream comprising mercaptans with liquid sulphur in a sulphide producing zone at elevated pressure and at a temperature in the range of from 300 to 450° C. to obtain a liquid stream comprising sulphur and sulphide compounds; (b) optionally separating the liquid stream obtained in step (a) into a first liquid phase enriched in liquid sulphur and a second liquid phase enriched in sulphide compounds; (c) combusting at least part of the sulphide compounds at elevated temperature in the presence of an oxygen-containing gas in a sulphur dioxide generation zone using a sulphide burner to which burner oxygen-containing gas is supplied, whereby at least part of the sulphide compounds is converted to sulphur dioxide to obtain a gas stream comprising sulphur dioxide.

Abstract: Apparatus and processes for the production of a sulfur dioxide-containing combustion gas are provided in which a sulfur-containing liquid is pneumatically atomized with a sulfur gun or lance that utilizes an atomizing gas to form an atomized combustion mixture for combustion in a sulfur furnace. The sulfur dioxide-containing combustion gas may be used in the manufacture of sulfuric acid by the contact process.

Abstract: Process for the production of sulfur, obtained in pure form, and possibly easily disposable even at ambient temperature, starting from hydrogen sulphide contained in natural gas, which includes: a) oxidizing a portion of hydrogen sulphide to sulfur dioxide; b) dissolving in water the sulfur dioxide obtained in step (a); c) carrying out the reaction (I): 2H2S+SO2?3S+2H2O (I) making the remaining hydrogen sulphide to react with the solution prepared in step (b); and d) using the thus obtained sulfur suspension for the production sulfur or, alternatively, to use it for the disposal of the sulfur itself in a site reserved for such purpose.

Abstract: Sulphur oxides are generated from a liquid stream of hydrogen sulphide by feeding the liquid stream to a vacuum stripper where the stream is contacted with a stripping gas including steam under reduce pressure. Hydrogen sulphide is transferred to the stripping gas, whereby a loaded stripping gas is obtained. Water in the loaded stripping gas is condensed producing a H2S rich stream. The H2S is then burned in the stream to produce a stream rich in oxides of sulphur.

Abstract: Recovering sulfur from a gas stream containing hydrogen sulfide by oxidizing the gas stream to convert the hydrogen sulfide in the gas stream to sulfur oxide, and thus form a sulfur oxide enriched gas stream. The sulfur oxide enriched gas stream is contacted with a solid, sulfation resistant adsorbent bed at relatively low temperatures to extract the sulfur oxides and retain them as sulfur compounds, thus forming a sulfur oxide depleted gas stream. The adsorbent bed is then contacted with an inert or reducing gas stream to reduce the retained sulfur compounds to sulfur and/or sulfur dioxide and thereby form an enriched sulfur and/or sulfur dioxide bearing stream. The elemental sulfur is recovered and/or the sulfur dioxide bearing stream may be recycled to the Claus unit for further conversion.

Abstract: The invention provides a method for a sulfur based hydrogen production cycle wherein the sulfur products are maintained in a gaseous state throughout the cycle. The cycle includes a decomposition of a gaseous phase sulfur trioxide to sulfur dioxide and water in a decomposition reactor and an oxidation of gaseous sulfur trioxide with H2O in an electrolyzer to form sulfur trioxide and hydrogen. Costs are reduced by elimination of energy costs previous necessary to convert the sulfuric products from liquid to gas and back again and by extending the lifespan of decomposition catalysts through the elimination of water in an SO2/SO3 stream.

Abstract: Carbon monoxide and carbonyl sulfide emissions are reduced in manufacturing processes, including titanium tetrachloride production processes. Gas is contacted with CO, COS, and an oxygen-containing gas with a suitable catalyst. The catalyst may be a metal oxide catalyst containing bismuth, cobalt and nickel, a xerogel or aerogel catalyst containing Au, Rh, Ru and Co in aluminum oxide/oxyhydroxide matrices, or a supported metal catalyst that contains at least one metal from the group Pd, Rh, Ru and Cu. In the latter case, the catalyst support is contains alumina or carbon. A catalyst composite of Au, Rh, Ru and Cr, and cerium oxide and lanthanum oxide may also be used.

Abstract: H2S is removed from an H2S-rich gas, and sulfur is produced, by a process in which the H2S-rich gas is reacted with SO2 in a reactor in the presence of an organic solvent and a catalyst, an H2S-containing off-gas is removed from the reactor and is combusted to produce an SO2-rich combustion gas. Preferably, the reactor off-gas is combusted with a substoichiometric amount of oxygen so that the combustion gas also contains water vapor and sulfur vapor. The combustion gas is cooled by direct quench or indirect heat exchange to produce an aqueous stream comprising primarily water and containing suspended solid sulfur and polythionic acids, e.g., a Wackenroder's liquid, and the aqueous stream is used to provide cooling for the H2S—SO2 reaction. Problems associated with production and handling of Wackenroder's liquids are overcome and sulfur values in these materials are recovered.

Abstract: A process is provided for the production of hydrogen from hydrogen sulfide by reacting carbon monoxide with hydrogen sulfide to produce hydrogen and carbonyl sulfide, and then reacting the carbonyl sulfide with oxygen to produce carbon monoxide and sulfur dioxide. The carbon monoxide is recycled back to the hydrogen sulfide reaction step. The catalyst used to promote the reaction between carbonyl sulfide and oxygen is an oxide of a metal, such as V, Nb, Mo, Cr, Re, Ti, W, Mn or Ta, which is supported on a support, such as TiO2, ZrO2, CeO2, Nb2O5 and Al2O3.

Abstract: Part of a hydrogen sulphide containing feed gas is burnt in a furnace 6 in the presence of oxygen or oxygen-enriched air. Sulphur dioxide is formed and reacts with remaining hydrogen sulphide to form sulphur vapour which is extracted by means of a condenser 16. The resulting sulphur vapour depleted gas stream is reduced to hydrogen sulphide in a reactor 22. Water vapour is removed from the gas mixture by condensation in a quench tower 32. A part of the resulting water-depleted gas stream is recycled to the furnace 6. Another part is sent for further treatment to form a purge stream.

Abstract: A process and apparatus for recovering sulphur from a combustible gas stream comprising hydrogen sulphide, air, commercially pure oxygen or oxygen-enriched air. The combustible gas stream are fed to a burner which fires into an elongate furnace. A longitudinally extending flame is created which as a relatively oxygen-poor endothermic hydrogen sulphide dissociation region, and a relatively oxygen-rich, intense hydrogen sulphide combustion region. Residual hydrogen sulphide reacts with sulphur dioxide formed by the combustion to produce sulphur vapour. The furnace has an aspect ratio of about 8:1. The flame diverges from its root to occupy at its maximum cross-sectional area at least about 80% of the cross-sectional area of the furnace interior coplanar therewith.

Abstract: In an exhaust-gas cleaning system and method for performing desulphating operations, a catalytic converter having oxidation properties is connected downstream of an NOx-adsorber, and a secondary-air feed device is provided between the NOx-adsorber and the catalytic converter having oxidation properties. The feed device is connected to a control device so that secondary air is introduced between the NOx-adsorber and the catalytic converter having oxidation properties during the desulphating operations.

Abstract: A process is provided for the thermal decomposition of contaminated sulfuric acid, which was obtained from the scrubbing of sulfur dioxide contaminated gases created in the pyrometallurgical production of metals. The contaminated sulfuric acid is concentrated to obtain a H2SO4 content of 70% to 80%, wherein, during the concentration step, a portion of the metal components, such as arsenic component, zinc sulfate, cadmium sulfate and copper sulfate, as well as halogens, are removed from the sulfuric acid. The concentrated and purified sulfuric acid is fed into the exhaust shaft of a smelting furnace so that the heat of the smelting furnace exhaust gases thermally decomposes the sulfuric acid into sulfur dioxide, water and oxygen.

Abstract: A process for desulfurization of a gaseous substrate containing O.sub.2, SO.sub.2, SO.sub.3, H.sub.2 SO.sub.4, H.sub.2 S, CS.sub.2, COS and/or organic sulfur-containing components. The combustible components are oxidized catalytically into H.sub.2 O, CO.sub.2, and SO.sub.2. The SO.sub.2 is further oxidized catalytically into SO.sub.3, which in the presence in the substrate of at least an equivalent amount of H.sub.2 O in the gas, is further hydrated and condensed as sulfuric acid. The process is conducted in two towers that are connected in series, each tower being loaded with a layer of inert material below a layer of oxidization catalyst preferably consisting of an acid resistant material with parallel, vertical channels. A preferred catalyst includes vanadium oxide supported on a silica carrier material and promoted with alkali metals. The process includes reversing a direction of gas flow in the towers after periods of about 1-40 minutes.

Abstract: A process is provided for the recovery of sulfuric acid from NH.sub.4 HSO.sub.4 and (NH.sub.4).sub.2 SO.sub.4 salts produced from the sulfuric acid hydrolysis of methylmercaptopropionaldehyde (MMP) cyanohydrin to produce 2-hydroxy-4-methylthiobutyric acid (MHA), which can be used as an additive in animal feed. The sulfate salts are combusted in a furnace to produce sulfur dioxide; the sulfur dioxide is contacted with an aqueous solution containing sulfuric acid and hydrogen peroxide, where the sulfur dioxide is converted into sulfuric acid. The product sulfuric acid is recovered.

Abstract: The invention relates to an all-metal catalyst for the oxidation of gaseous sulphur compounds, more particularly hydrogen sulphide, in an oxygen-containing atmosphere, said catalyst consisting of a metal alloy of 5 to 70% by weight nickel and 30 to 95% by weight copper as residue thermally treated at temperatures of 400.degree. to 1000.degree. C. in an oxygen-containing atmosphere for 0.25 to 5 hours.

Abstract: Waste/industrial effluents containing contaminating amounts of organic and/or inorganic species, for example effluents containing sulfate or sulfuric acid values, or effluents emanating from the production of methionine, are safely and effectively purified in high yield, by first establishing, in a first reaction zone, an axially helically descending flowstream defining a phase of combustion, this phase of combustion comprising ignited admixture of a first oxidizing fluid and a combustible fuel; ejecting the phase of combustion through a port of restricted flow passage to impart an axially symmetrical vortex flow thereto and flash-expanding same into a second reaction zone; introducing effluent to be purified into the axially symmetrical vortex thus formed; and also introducing additional oxidizing fluid into such axially symmetrical vortex, whereby the effluent is disintegrated into a multitude of droplets entrained in unit volumes of the phase of combustion and thermally treated in the second reaction zone.

Abstract: A method is disclosed for treating sulfur containing waste streams, comprising:a) injecting said sulfur containing waste streams into a sulfuric acid regeneration unit so as to produce a sulfur dioxide containing effluent;b) passing a portion of said sulfur dioxide containing effluent to a Claus thermal reactor, andc) diverting a portion of said portion of said sulfur dioxide containing effluent of step b to a Claus catalytic reactor that is downstream from said Claus thermal reactor in an amount sufficient to maintain the average temperature in the Claus thermal reactor to be less than 3,250.degree. F.

Abstract: A process and apparatus for removal of volatile divalent sulfur compounds from waste gases. Volatile organic compounds are advantageously removed in the same process. The divalent sulfur compounds are oxidized in a combustion zone, then preferably removed from the combustion gas, as by absorption or adsorption. The divalent sulfur compound and any VOCs are oxidized in either a catalytic or thermal combustion zone, after which the combustion gases are cooled by transfer of heat to the contaminated gases entering the combustion zone. A regenerative heat transfer reaction system is preferably used. Catalyst may comprise a noble metal, or oxides of Cr, Cu and/or Mn. A catalyst degraded by deposition of sulfate or sulfite salts on its surface may be reactivated by in situ decomposition of such salts. Reactivation also removes such salts from the heat transfer storage beds of a regenerative heat transfer reaction system.

Abstract: Process for removing hydrogen sulfide at low concentration in a gas containing water vapor. The gas is cooled to a temperature below the dew point of water, which condenses and separates the water. The dry gas is scrubbed free of hydrogen sulfide by an H.sub.2 S-absorbent solvent forming a purified gas. The purified gas is contacted and rehydrated with heated water so that the water content as water vapor corresponds to a mass flow rate of water substantially equal to the mass flow rate of the water present in the H.sub.2 S-containing gas before cooling. An apparatus for carrying out the process is disclosed.

Abstract: A process for the thermal decomposition of metal sulphate mixtures at temperatures from 800.degree. to 1100.degree. C. under oxidizing conditions, in which the metal sulphate mixtures are mixed with roasting residue and reacted together with fuels in the decomposition reactor to form roasting residue and SO.sub.2 -containing gases from roasting wherein the roasting residue admixed with the sulphate mixture is the finely divided fraction of the resulting roasting residue which is separated from the stream of gas in an electrostatic gas purification apparatus and returned to the decomposition reactor.This procedure has an advantageous influence on the formation of coarse roasting residue and also significantly reduces the proportion of undecomposed, water soluble sulphates in the roasting residue.

Abstract: An H.sub.2 S-containing gas is combusted with oxygen in at least one burner, which discharges into a combustion chamber. The resulting mixed gases contain H.sub.2 S, SO.sub.2, free hydrogen and elementary sulfur and are at temperatures of about 900.degree. to 2000.degree. C. At temperatures of about 900.degree. to 2000.degree. C. at least part of the free hydrogen is removed from said mixed gases. The free hydrogen may be removed from the mixed gases, e.g., through membranes.

Abstract: Sodium sulfate-containing residues are worked up by reducing the sulfate by a process in which the sulfate or a mixture or solution of the sulfate is thermally cleaved by adding oxygen, air or oxygen-enriched air at above 1000.degree. C., in particular above 1200.degree. C., under reducing conditions to give gaseous sulfides and oxides of sulfur as well as alkaline slag. The sulfur compounds contained in the gaseous reaction products can be further processed to sulfur, sulfur dioxide and sulfuric acid.

Abstract: The present invention relates to the coproduction of a combustible gas stream usable as an energy source, a sulfur-dioxide-containing second gas stream usable as a source of oxidant in the gasification of coal, and a sulfur-dioxide-containing third gas stream usable as a feedstock for the production of sulfuric acid. The process includes heating coal in a coal gasification zone in the presence of an oxygen and sulfur dioxide-containing atmosphere under partial coal gasifying conditions to produce a carbonaceous char and a crude coal gas stream. Sulfur-containing compounds are removed from the coal gas stream and converted to elemental sulfur. The carbonaceous char is combined with gypsum to form a feed mixture. The non-gypsum portion of the feed mixture contains sufficient reducing potential to release substantially all of the sulfur in the gypsum as gaseous compounds of sulfur in a +4 or lower oxidation state.

Abstract: A pelletized mixture of gypsum, carbonaceous material and pyrite is charged to a travelling grate where the charge is heated under suitable conditions to produce a solid sintered material which has a broad spectrum of applications due to its chemical and physical properties and a gaseous effluent containing sulfur dioxide, sulfur or mixtures thereof.

Abstract: Sulfur containing organics, e.g., carbon disulfide carbon oxysulfide, or a mercaptan, are oxidized to sulfur dioxide in gaseopus phase, whether alone or conjointly with hydrogen sulfide and/or elemental sulfur, per se, by passing a gaseous stream thereof, at elevated temperature, over a catalyst composition which comprises (i) a carrier substrate comprising titanium oxide, silica, zirconium oxide, silica-magnesia, silica-zirconia, silica-titanium oxide, zirconia-titanium oxide, or a zeolite, or admixture thereof, and (ii) a catalytically effective amount of at least one catalytically active element of Group Ib, IIb, IIIb, Vb, VIb, VIIb, VIII or Va of the Periodic Table, e.g., copper, silver, zinc, cadmium, yttrium, a lanthanide, chromium, molybdenum, tungsten, manganese, iron, cobalt, rhodium, iridium, nickel, palladium, platinum, tin and/or bismuth, but said catalyst composition being devoid of mixed oxide of spinel type.

Abstract: A coal fired power plant includes a coal gasification zone where coal is gasified in the presence of an oxidant-lean atmosphere under partial coal gasifying conditions to produce a carbonaceous char and a crude gas stream, an acid separating zone where sulfur-containing compounds are separated from the crude gas stream to produce a combustible gas stream, and a converting zone where the sulfur-containing compounds are converted to elemental sulfur. The combustible gas stream and the carbonaceous char are fed into a boiler which drives a generator to produce electricity; portions of the carbonaceous char product and the combustible gas stream are diverted into a gypsum desulfurization zone. SO.sub.2 -containing flue gas from the boiler is fed into a flue gas desulfurization zone. There, the SO.sub.2 -containing flue gas is contacted with lime and limestone to produce gypsum.

Abstract: A gas mixture including sulphur dioxide is recovered from sulphate waste material by burning a fuel to form a flame zone, introducing sulphate waste material into the zone and introducing pure oxygen or other oxygen-rich gas into the flame zone to support combustion of the fuel and to generate a flame of sufficient temperature to crack solid sulphate waste material and thereby liberate sulphur dioxide therefrom. Solids exiting the flame zone are separated from the gaseous combustion products. The sulphate waste material may be taken from a plant for making titanium dioxide pigment by the sulphate route.

Abstract: A process for the preparation of sulphur dioxide by the thermal decomposition of metal sulphates in a fluidized bed reactor with sulphur-containing reducing agents and energy suppliers, characterized in that a mixture comprising the metal sulphates, the sulphur-containing reducing agents and 75 to 99% of the energy suppliers is fed into the fluidized bed reactors and the remainder of the energy suppliers is introduced separately into the fluidized layer of the fluidized bed reactor.

Abstract: The present invention relates to the coproduction of a combustible feed gas stream useable as an energy source and a sulfur-containing second gas stream useable as a feedstock for the production of sulfuric acid. The process includes heating coal in the presence of an oxygen-lean atmosphere under partial coal gasifying conditions to produce a solid carbonaceous char and a crude coal-gas stream. Sulfur-containing compounds are removed from the coal gas stream and converted to solid sulfur-containing materials. The solid sulfur-containing materials are combined with the solid carbonaceous char and gypsum to form a feed mixture. The non-gypsum portion of the feed mixture contains sufficient reducing potential to release substantially all of the sulfur in the gypsum as gaseous compounds of sulfur in a +4 or lower oxidation state. The feed mixture is heated under reducing conditions to produce a sulfur-containing second gas stream and a solid sintered product.

Abstract: The present invention is related to a method for preventing the formation of NH.sub.4 HSO.sub.4 during the noncatalytic reduction of nitric oxide by ammonia or ammonia precursors in combustion effluents. The formation of this sticky and corrosive substance inside combustion units is an extreme limitation upon the usefulness of nitric oxide reduction processes, particularly in boilers, furnaces, and other combustion devices.The present invention specifically teaches the use of methanol to reduce SO.sub.3 in the effluent stream to SO.sub.2. The noncatalytic reduction of SO.sub.3 by methanol is selective in that a large fraction of the SO.sub.3 is converted to SO.sub.2, while on a percentage basis very little oxygen is consumed. In addition, the process of the present invention allows the amount of methanol to be limited such that significant amounts of carbon monoxide are not produced and emitted with the effluent stream.

Abstract: Molybdenite, MoS.sub.2, is completely converted into molybdenum dioxide, MoO.sub.2, by mixing MoS.sub.2 with petroleum or coal tar pitches and heating in air at 400.degree.-600.degree. F.

Abstract: A method is disclosed for recovering gallium and/or germanium from fly ash which comprises pelletizing the fly ash, treating the pellets in the presence of an oxidizing gas at a temperature of from about 900.degree. C. to just below the fusion temperature of the pellets, treating the pellets in the presence of a reducing gas at the same temperature range, and recovering gallium and/or germanium suboxides from the gas.

Abstract: In the recovery of waste heat from flue gas containing particulate solids, CO.sub.2, SO.sub.2, SO.sub.3 and H.sub.2 O, several improvements are provided, e.g., passing hot flue gas, e.g., from a power plant, over heat exchange surface attackable by sulfuric acid, e.g., in a combustion air preheater, so as to release heat to said heat exchange surface and to partially cool said flue gas to a temperature within the range of about 350.degree. F.

Abstract: Catalysts comprising bismuth and vanadium components are highly active and stable, especially in the presence of water vapor, for oxidizing hydrogen sulfide to sulfur or SO.sub.2. Such catalysts have been found to be especially active for the conversion of hydrogen sulfide to sulfur by reaction with oxygen or SO.sub.2.