Abstract: The present invention provides a process for concentrating sulphuric acids with concentrations of 90% to 98% H.sub.2 SO.sub.4 and temperatures of 160.degree. C. to 270.degree. C. into sulphuric acid with concentrations of 96% to 98.8% H.sub.2 SO.sub.4 by contacting the acid countercurrently in a packed tower with hot air or with hot process gas containing up to 6% SO.sub.3 and up to 30% H.sub.2 O and with inlet temperatures to the tower of 350.degree. C to 600.degree. C. The H.sub.2 O and H.sub.2 SO.sub.4 evaporated in the tower is contained in a stream of offgas from which the H.sub.2 SO.sub.4 thereafter is removed by controlled condensation The invention relates, in particular, to concentrating the product acid from wet gas sulphuric acid plants in which condensation of H.sub.2 SO.sub.4 takes place in the presence of excess H.sub.2 O in the process gas in air cooled, vertical glass tubes.

Abstract: Sulfuric acid which contains dilute organic phosphorus compounds and other impurities and is obtained, for example, during preparation of sulfonated arylphosphines, is purified by extraction with an amine which is sparingly soluble or insoluble in water.

Abstract: This invention presents a sulphurous acid generator which employs a combination of novel blending contact and mixing mechanisms which maximize the efficiency and duration of contact between sulphur dioxide gas and water to form sulphurous acid in an open nonpressurized system, without employing a countercurrent absorption tower.

Abstract: A process is provided for removing hydrogen sulfide out of gas, such as gas separated from geothermal brine, by passing the hydrogen sulfide containing gas and oxygen containing gas through a bioreactor containing bacteria, such as Beggiatoa, Thiothrix and Thiobacilli, supported on a support so that the bacteria oxide the hydrogen sulfide into elemental sulfur, which is subsequently oxidized into sulfuric acid. The flow of the gases through the bioreactor is cyclically reserved about every 12 hours to about 5 days so as to provide a better sulfur distribution in the support, resulting in more efficient oxidation of the elemental sulfur into sulfuric acid. Hydrogen sulfide depleted gas and sulfuric acid are discharged from the bioreactor. A plurality of bioreactors may be used, connected in series or in parallel.

Abstract: A process is provided for the destruction of nitrogen oxides in sulfuric acid by adding a reducing agent, such as hydrazine, sulfamic acid or urea, and an oxidizing agent, such as hydrogen peroxide or persulfates, into the nitrogen oxides contaminated sulfuric acid. The nitrogen oxides contaminated sulfuric acid is treated at a temperature between 15.degree. C. and 100.degree. C.

Abstract: A process and apparatus for reducing particulate, nitrogen oxides ("NOx"), sulfur dioxide ("SO.sub.2 "), and mercury ("Hg") emissions from the combustion exhaust of fossil fuel fired plants while producing an end product that is commercially useful, comprising the steps of oxidizing Hg, NOx and SO.sub.2 using a barrier, pulse, corona, or electron beam electrical discharge apparatus to produce HgO and the acids HNO.sub.3 and H.sub.2 SO.sub.4, collecting the HgO, acids and particulates in a wet ESP, and separating the particulates from the collected acid mixture, then separating and concentrated the acids for industrial use.

Abstract: A new chemical reaction container (43) is provided which is suitable for a process plant the production of sulfuric acid according to the contact process. It comprises a cylindrical envelope surface and is divided by vertical separation walls into at least two sections, usually three. Each section has an inlet and an outlet, the separation walls at their bottom parts having one or several openings for making contact possible between the different sections. The advantage of this is that both the drying of the process gas, the interpass absorption step and the final absorption step may be conducted in one and the same reactor, instead of three separate reactors, as done previously. This saves both space and material. Further are provided a plant and a process for the production of sulfuric acid according to the contact process, which plant and which process comprise the above reactor container.

Abstract: A process employing a fixed-resin bed Acid Retardation Unit (ARU) to separate spent acid from chlorine dioxide generators into a de-acidified sodium sulfate component and a purified sulfuric acid component. The de-acidified sodium sulfate produced is returned to the chemical recovery cycle of the kraft mill in place of acidic chlorine dioxide generator effluent thereby avoiding the destruction of alkalinity in pulp mill liquors. In addition, sulfuric acid is purified providing an opportunity for reuse in various mill applications, and/or concentrated and recycled to the generator. Alternatively, to avoid high evaporation costs, the purified acid can be used to regenerate a cation-exchange unit (CEU) used in the conversion of sodium chlorate to a sodium chlorate/chloric acid mixture which is fed to the generator in place of sodium chlorate and sulfuric acid. Using this approach, the sulfuric acid requirement of chlorine dioxide generators and, in turn, the amount of acidic generator effluent can be reduced.

Abstract: Cement is produced by forming a moist mixture of a flue gas desulfurization process waste product containing 80-95 percent by weight calcium sulfite hemihydrate and 5-20 percent by weight calcium sulfate hemihydrate, aluminum, iron, silica and carbon, agglomerating the moist mixture while drying the same to form a feedstock, and calcining the dry agglomerated feedstock in a rotary kiln. Sulfur dioxide released from the calcium sulfite hemihydrate and calcium sulfate hemihydrate during calcination may be used to produce sulfuric acid, while heat recovered in the process is used to dry the agglomerating feedstock.

Abstract: A method for manufacturing sulfuric acid from a gas containing sulfur oxides, water and oxygen comprising subjecting the sulfur oxides rich gas to either an adiabatic compressor or a flame impinger to rapidly increase the temperature so that the sulfur dioxide in the gas is converted into sulfur trioxide and cooling the sulfur trioxide rich gas to produce sulfuric acid.

Abstract: A method for determination of activity of a cholesterol oxidase comprises the following steps. A monomolecule film comprising a sterol and a phospholipid is formed on a surface of a cholesterol oxidase solution. Subsequently, a surface pressure of the monomolecule film is measured in order to find a rate of increase in the surface pressure of the monomolecule film where a magnitude of the activity of the cholesterol oxidase is defined by the rate of increase in the surface pressure.

Abstract: The process will recover sulfuric acid on the 90-95% concentration range by roasting of ferrous sulfate hydrate crystals at high temperature under retort conditions. In the first step of the recovery process 6 (see FIG. 1) hydroxide slurry is reacted with the waste stream, and ferrous sulfate crystals obtained. In the second step 9 iron sulfate crystals are roasted and water of hydration reacts with sulfate and sulfur trioxide to produce sulfuric acid in a retort operation. The sulfuric acid and sulfur trioxide are condensed or absorbed in water or dilute sulfuric acid and are of a high purity, leaving iron oxide as a recovered carrier. In the third step, this iron oxide/hydroxide is reduced 13 and used to produce a slurry, which is pumped back to react with the entering sulfuric acid waste stream.

Abstract: A process for producing high-purity sulfuric acid, comprising: an absorption step of causing water to contact sulfuric acid anhydride in a gaseous state which may possibly contain sulfurous acid gas as an impurity, so as to cause the sulfuric acid anhydride to be absorbed into the water, thereby to provide sulfuric acid; a stripping step of subjecting the sulfuric acid to stripping by use of air, thereby to separate and remove the sulfurous acid gas in the sulfuric acid; and a transport step of subjecting at least a portion of the sulfuric acid to liquid transportation by means of a circulating pump; wherein the temperature of the liquid at the inlet port of the circulating pump is 0.degree.-30.degree. C. When the above process is used, it is possible to produce high-purity sulfuric acid from which metal constituents and sulfurous acid gas as impurities have highly been removed.

Abstract: A process for removing SO.sub.2 from a gas mixture including SO.sub.3 and SO.sub.2 having a volume ratio of SO.sub.3 to SO.sub.2 greater than 1. The process includes intimately contacting the gas mixture in a contacting zone, removing a stream of purified gas containing less SO.sub.2 than the gas mixture from an upper portion of the contacting zone, and removing a stream of sulfuric acid from a lower portion of the contacting zone. Also provided are processes for manufacturing sulfuric acid utilizing the process for removing SO.sub.2 which allow increasing the production of concentrated sulfuric acid solutions by producing more sulfur trioxide without an increase of sulfur dioxide emissions.

Abstract: The present invention relates to a process for the removal of sulphur dioxide from waste gases which process comprises contacting a waste gas containing sulphur dioxide with an aqueous solution containing sulphuric acid, hydrogen bromide and bromide to form sulphuric acid and hydrogen bromide; catalytically oxidizing in the vapor phase the hydrogen bromide formed to bromine and thereafter recycling the bromine to the first step of the process.

Abstract: A process for the preparation of sulfuric acid by burning the oxidizable components of a feed solution obtained as a byproduct of the preparation of 2-hydroxy-4-(methylthio)butyric acid ("HMBA") by hydrolysis of 2-hydroxy-4-(methylthio)butyronitrile ("HMBN"). A combustion gas containing sulfur dioxide is produced. The combustion gas is cooled to condense water and sulfuric acid, then mixed with a source of oxygen to produce a feed gas containing at least about 0.9 moles oxygen per mole sulfur dioxide. The feed gas is passed over a catalyst for the conversion of sulfur dioxide to sulfur trioxide at a temperature effective for the conversion. Sulfur trioxide may be absorbed in concentrated sulfuric acid to generate additional sulfuric acid which may be recycled and used for hydrolysis of HMBN in the preparation of HMBA.

Abstract: The formation of SO.sub.3 mists is prevented by covering the oleum with a natural silicate excluding sand.

Abstract: An apparatus and method for producing a product, such as hydrogen halide gas or sulfuric acid, in a regenerator furnace subsystem from a waste containing a non-gasifiable impurity. The method of the invention includes directing a waste, containing a non-gasifiable impurity into a reaction zone, containing a molten metal bath, in a reactor maintained under conditions sufficient to dissociate the waste and to form a gasified feed component and a non-gasifiable impurity. The gasified feed component is then directed from the reactor to a regenerator furnace subsystem, maintained under conditions sufficient to convert the gasified feed component to the desired product.The apparatus of the invention includes a reactor having a waste inlet and a gaseous effluent, a reaction zone containing a molten-metal bath for dissociating the waste, containing a non-gasifiable impurity, and forming a gasified feed component, and a lance for injecting the waste into the reaction zone.

Abstract: A method and apparatus for producing SO.sub.2 -containing gas and cement clinker by splitting waste gypsum and anhydrite, using paper fibers as the reducing agent, and firing the splitting residue with additives. The cement forming additives are formed into a mixture with the anhydrite and the mixture is compacted before the final drying and calcining, whereupon the anhydrite containing mixture is subjected to the splitting reaction and firing to form the clinker.

Abstract: The method for the production of sulphur trioxide, operating in a non-stanary regime, intend for sulphuric acid production.The aim of the present invention is to provide a method for the production of SO.sub.3 by catalytic oxidation of SO.sub.2, contained in an inlet gas flow, providing a stable regime of operation of wide limits of variation of the flow rate and the concentration of SO.sub.2 in the input gas.The essence of the invention is in this, that between the two layers of the first step of oxidation in a two-step three-layer contact apparatus, the gas flow is partially cooled in an inner heat-exchanger-mixer and part of the heat of the reaction of oxidation of SO.sub.2 in the first stage of oxidation is passed to the second stage of oxidation by means of the gas flow coming out of the intermediate absorption, containing unoxidized SO.sub.2 from the first stage.

Abstract: A method of treating a flow of gas containing oxidized sulphur compounds, such as an exhaust gas from coal combustion, comprising the steps of (i) treating the flow of gas to obtain a first component flow containing at least 30% of the total oxidized sulphur compounds and a second component flow containing at least a part of the remainder of the total oxidized sulphur compounds; (ii) converting the first component flow into a concentrated gas containing at least 2.5% by volume of sulphur compounds; (iii) converting oxidized sulphur compounds in the second component flow into hydrogen sulphide; and (iv) supplying the concentrated gas of step (ii) and the hydrogen sulphide of step (iii) to an apparatus for manufacturing either sulfuric acid, sulphur dioxide or elemental sulphur.

Abstract: A process for removing SO.sub.2 from a gas mixture including SO.sub.3 and SO.sub.2 having a volume ratio of SO.sub.3 to SO.sub.2 greater than 1. The process includes intimately contacting the gas mixture in a contacting zone, removing a stream of purified gas containing less SO.sub.2 than the gas mixture from an upper portion of the contacting zone, and removing a stream of sulfuric acid from a lower portion of the contacting zone. Also provided are processes for manufacturing sulfuric acid utilizing the process for removing SO.sub.2 which allow increasing the production of concentrated sulfuric acid solutions by producing more sulfur trioxide without an increase of sulfur dioxide emissions.

Abstract: A coal fired power plant includes the catalytic reduction of NO.sub.x in the flue gas and the catalytic oxidation of SO.sub.2 to SO.sub.3 followed by the hydration of the SO.sub.3 to H.sub.2 SO.sub.4 vapor and then the condensation to H.sub.2 SO.sub.4 liquid. The condensation takes place in a wet sulfuric acid condenser by heat exchange with incoming combustion air. A portion of the heat picked up by that combustion air is used to provide a portion of the heat for the condensate from the steam turbine. The combustion air is then fed to an air preheater and to the steam generator as primary and secondary combustion air.

Abstract: The concentration of sulfuric acid exiting a countercurrent SO.sub.3 absorber is controlled by controlled addition of water vapor to the SO.sub.3 -containing process gas stream entering the absorber. The novel means of concentration control is useful for control of the acid concentration gradient in an SO.sub.3 absorption process and apparatus for high temperature absorption, so as to achieve high temperature absorption heat recovery while minimizing corrosion and formation of acid mist.

Abstract: An improved process for the recovery of high grade energy from a contact sulfuric acid manufacturing process. Improvements include: injection of steam between an intermediate catalyst stage and a heat recovery absorption tower and/or a heat exchanger for transfer of heat from conversion gas to high pressure boiler feed water; use of a condensing economizer for recovery of the vapor phase energy of formation of sulfuric acid from a wet conversion gas; and use of heat recovery system absorption acid for preheating air to a sulfur burner, the heat transferred to the combustion air being recovered at high pressure and temperature in a waste heat boiler.

Abstract: A process for the preparation of sulfuric acid by burning the oxidizable components of a feed solution obtained as a byproduct of the preparation of 2-hydroxy-4-(methylthio)butyric acid ("HMBA") by hydrolysis of 2-hydroxy-4-(methylthio)butyronitrile ("HMBN"). A combustion gas containing sulfur dioxide is produced. The combustion gas is cooled to condense water and sulfuric acid, then mixed with a source of oxygen to produce a feed gas containing at least about 0.9 moles oxygen per mole sulfur dioxide. The feed gas is passed over a catalyst for the conversion of sulfur dioxide to sulfur trioxide at a temperature effective for the conversion. Sulfur trioxide may be absorbed in concentrated sulfuric acid to generate additional sulfuric acid which may be recycled and used for hydrolysis of HMBN in the preparation of HMBA.

Abstract: In order to efficiently and easily recover a spent sulfuric acid exhasuted, for example, in an acid washing liquid or in producing titanium dioxide by a sulfate method in a large amount, as highly concentrated sulfuric acid, bivalent iron ions in the spent sulfuric acid containing metal sulfate are first oxidized into trivalent iron ions, hydrochloric acid is added to such a liquid and then solvent extraction is carried out.

Abstract: A process, using regenerable adsorption materials, for purifying exhaust gases that have been contaminated with at least SO.sub.2, a heavy metal such as mercury and additional toxic gases such as dioxins and furans is disclosed. The process includes adsorbing the exhaust gases where the gas if freed of SO.sub.2, heavy metal and additional toxic gases, and optionally subjecting the gas from the adsorber to further treatment. The contaminated adsorber material is subjected to an oxygen-free regeneration process and the gas from the regeneration process is scrubbed and subsequently processed into pure sulfuric acid in a nitric oxide-sulphuric acid plant.

Abstract: The production of titanium dioxide by the sulphate process generates waste substances such as the wash filtrates, which are formed in the washing of titanium dioxide hydrate, and waste gases which contain sulphur dioxide. In this improved process the wash filtrate is used to remove the sulphur dioxide from the waste gas while the sulphuric acid content of the wash filtrate is raised and the sulphuric acid-containing process solution thus obtained is used within the scope of the titanium dioxide production process. The waste gas and the wash filtrate are passed countercurrently through a series of several washing steps and are contacted with each other by introducing the wash liquid into the waste gas in a finely divided form in scrub towers. The sulphuric acid content of the washing fluid is stepwise changed from washing stage to washing stage. The sulphur dioxide content of the waste gas is reduced to values that may be discharged into the ambient atmosphere.

Abstract: Solid sodium sesquisulfate is metathesized by water to neutral anhydrous sodium sulfate and to recover the acid values therefrom by employing a dynamic leaching of the solid phase sodium sesquisulfate, to provide an acid medium for recycle to a chlorine dioxide generating process producing the sodium sesquisulfate without significantly increasing the evaporative load on the generator.

Abstract: In the continuous production of oleum having a concentration of 10 to 45% by weight SO.sub.3 and/or sulfuric acid having a concentration of 94 to 100% by weight H.sub.2 SO.sub.4 by burning sulfur with atomospheric oxygen on the principle of overstoichiometric or understoichiometric burning, cooling the resulting SO.sub.2 -containing gas to 390.degree.-480.degree. C., catalytically reacting the cooled gas to SO.sub.3 -containing gas on a vanadium-containing catalyst on the principle of single- or double-contact catalysis, absorbing the SO.sub.3 -containing gas after cooling and, optionally, separating liquid from the gas after absorption, followed by recovering energy, the improvement which comprises effecting the burning of the sulfur with atomospheric oxygen in the presence of a dry SO.sub.2 -containing gas which contains up to 5,000 ppm (NO).sub.x expressed as NO.

Abstract: Process for conditioning waste sulfuric acid which is prone to precipitation of tars or resins, which comprises adding emulsifiers, preferably long-chain polyethers, to the waste sulfuric acid.

Abstract: In a process such as the preparation of sulphuric acid wherein a wrought or cast material or a welding filler is contacted with hot concentrated sulphuric acid or oleum of up to 10 wt-%, the improvement which comprises forming the contact portion of said wrought or cast material or said filler of an austenitic iron-nickel-chromimum-silicon alloy comprising about15.5 to 17.5 wt-% nickel10 to 12 wt-% chromium5.7 to 6.5 wt-% siliconup to max. 0.06 wt-% carbonup to max. 1.5 wt-% manganeseup to max. 0.03 wt-% phosphorusup to max. 0.03 wt-% sulphurup to max. 0.15 wt-% titaniumup to max. 0.8 wt-% zirconiumup to max. 0.2 wt-% nitrogen andup to max. 0.3 wt-% molybdenumand the remainder iron,together with minimal quantities of normally present impurities, including the deoxidizing elements magnesium, aluminum and calcium.

Abstract: A method is provided for the dissolution of at least one precious metal selected from the group consisting of platinum group metals, gold and silver. The method comprises subjecting a material containing at least one of the precious metals to dissolution with a sulfuric acid solution maintained at a pH at least sufficient to complex the precious metal with bromide ions in the presence of an oxidizing agent, the amount of bromide ions in the solution being at least sufficient to form a soluble complex of the precious metal. The amount of oxidizing agent is at least sufficient to maintain a redox potential at least high enough to convert the precious metal to an ionic form conducive to forming a soluble bromide complex thereof.

Abstract: A process for the purification and concentration of sulfuric acid contained with nitric acid by-products and organic components pursuant to the mixed acid nitration of aromatics.

Abstract: Chemically and thermally stable monolithic catalysts are disclosed having platinum or alkali metal-vanadium active phases for use in the conversion of sulfur dioxide to sulfur trioxide. The platinum catalyst comprises a foraminous ceramic support which has at its wall surfaces a high surface area substrate for an active catalyst phase, and a combination of a platinum active phase and a promoter on the substrate. The substrate preferably comprises silica, provided, for example, by application of a silica washcoat. The promoter is selected from among compounds of zirconium, hafnium and titanium.The alkali-vanadium catalyst comprises a foraminous ceramic support having a porous silica substrate for the active phase at its foraminal wall surfaces. An alkali metal-vanadium active catalyst is in the pores of the porous silica.

Abstract: The present invention provides a flue gas conditioning system and method for generating conditioning agent used in the removal of entrained particles in a flue gas flow with an electrostatic precipitator. The invention involves the use of a catalytic converter movable between an operative position where the flue gas flows through the catalyst and converts SO.sub.2 contained in the flue gas to SO.sub.3 when conditioning agent is needed and an inoperative position where the flue gas does not flow through the catalyst when conditioning agent is no longer needed. The movable catalytic converter and related assembly may take variable configurations to accommodate various flue gas ductworks and space limitations.

Abstract: Sodium sesquisulfate produced in crystalline form in a high acidity methanol-based highly efficient chlorine dioxide generating process is converted by metathesis to crystalline anhydrous neutral sodium sulfate and the acid recovered as a result is recycled to the chlorine dioxide generating step. The metathesis is effected by contacting the crystalline sodium sesquisulfate with aqueous sodium chlorate solution, aqueous sodium chloride solution, aqueous methanol or water alone. The metathesis is effected in such manner as to minimize the additional evaporative load imposed on the chlorine dioxide generating process by the metathesis medium.

Abstract: When condensing sulfuric acid from gases containing sulfuric acid vapor and steam in excess, e.g. originating from a power station, a substantial decrease of the amount minute droplets of sulfuric acid (the so-called acid mist) escaping to the surroundings is obtained, even in cases where the sulfuric acid plant is equipped with an aerosol filter, if minute nucleation cores are incorporated into the gas in an amount of 10.sup.9 to 10.sup.12 solid particles per Nm.sup.3 per 0.1 % H.sub.2 SO.sub.4 -vapor in the gas. The nucelation cores may, e.g., be generated by combusting hydrocarbons with>2 carbon atoms or silicones, or added as smoke from an electric arc or welding.

Abstract: A method and apparatus are disclosed for removing pollutants, especially oxides of sulphur and nitrogen, from boiler plant flue gases. A series of heat exchange steps cool the gas and condense acidic condensates. SO.sub.3 is removed by condensation, and SO.sub.2 is removed by either extraction or a combination of oxidation and condensation.

Abstract: A noncatalytic process for producing sulfur trioxide and sulfuric acid in which sulfur is combusted with an oxygen-rich gas in the presence of recycled sulfur dioxide-rich gas to form sulfur trioxide which is absorbed in sulfuric acid and yield a sulfur dioxide rich gas which is compressed to form the recycled sulfur dioxide rich gas.

Abstract: An improved process for the recovery of high grade energy from a contact sulfuric acid manufacturing process. Improvements include: injection of steam between an intermediate catalyst stage and a heat recovery absorption tower and/or a heat exchanger for transfer of heat from conversion gas to high pressure boiler feed water; use of a condensing economizer for recovery of the vapor phase energy of formation of sulfuric acid from a wet conversion gas; and use of heat recovery system absorption acid for preheating air to a sulfur burner, the heat transferred to the combustion air being recovered at high pressure and temperature in a waste heat boiler.

Abstract: A method for the extraction of valuable minerals and precious metals from oil sands ore bodies or other related ore bodies that is synergistically unique in the arrangement of processes for production of valuable minerals and precious metals in an economically and environmentally acceptable manner. The oil sands ores from oil sands ore bodies and other related ores from other related ore bodies including overburden and interburden mineral ores are crushed, the hydrocarbons, if any exists in worthwhile quantities, are recovered and the resulting coarse sands, other related ores and fines streams are processed in a definite sequence using known processes to recover the valuable minerals and precious metals values. All reactants and reagents, including water, are recycled in the method and tailings ponds are not required. Heat recovery is used extensively to cogenerate almost all of the process steam and process electrical requirements for the method.

Abstract: A process for the purification of hot exhaust gases containing dust, sulphur dioxide and/or hydrogen chloride and/or hydrogen fluoride and having a water vapor partial pressure of at least 15 volume %, whereina) the hot exhaust gases are cooled to temperatures below 135.degree. C. by scrubbing with 60-75% sulphuric acid,b) the exhaust gases from a) are cooled to 60.degree.-80.degree. C. by contact with 5-20% sulphuric acid,c) the exhaust gases from b) are desulphurized in contact with moist active charcoal to form sulphuric acid,d) the sulphuric acid formed in c) is raised to a concentration of 5 to 20% H.sub.2 SO.sub.4 in contact with the hot exhaust gases,e) the 5 to 20% sulphuric acid formed in d) is evaporated to a concentration of 60 to 80% H.sub.2 SO.sub.4 by the heat obtained from cooling the exhaust gases of a) andf) prior to stage e) HCl and/or HF is removed from a mixture of 5 to 20% H.sub.2 SO.sub.4 from d) with 60 to 80% sulphuric acid.

Abstract: A system for cooling flue gases from a fossil fuel boiler plant, and removing pollutants from the flue gas, is disclosed. In a first section of the apparatus, heat exchange cools the flue gas to just above the condensation point of water, and condensed H.sub.2 SO.sub.4 is collected. In a second section, the gas is cooled further and an acid-containing condensate is collected.

Abstract: In the processing of hot concentrated sulfuric acid or oleum in steel apparatus, the improvement wherein said apparatus is formed of an alloyed material comprising an iron-chrome-nickel-silicon alloy containing 13 to 32% by weight Cr, 5 to 25% by weight nickel and 4 to 9% by weight Si and having a structure containing more than 10% delta-ferrite.

Abstract: An improved process for manufacture of sulfuric acid by catalytic oxidation of wet sulfur dioxide gas. Wet conversion gas is contacted with sulfuric acid in a heat recovery stage to effect absorption and generate the heat of absorption. Wet gas having a mole ratio of sulfur trioxide to water vapor of at least 0.95 is introduced into the heat recovery stage at a temperature above the dew point of the gas. Sulfuric acid is introduced into the heat recovery absorption stage at a temperature of at least about 170.degree. C. and a concentration between about 98.5% and about 99.5%. The sulfuric acid stream as discharged from the absorption stage is at a temperature of at least about 190.degree. C. and has a concentration between about 99% and about 100%. The heat of absorption is recovered from the discharge absorption acid stream in useful form by transfer of heat to another fluid in a heat exchanger, the another fluid being heated to a temperature of at least about 140.degree. C.

Abstract: Sodium sesquisulfate produced in crystalline form in a high acidity methanol-based highly efficient chlorine dioxide generating process is converted by metathesis to crystalline anhydrous neutral sodium sulfate and the acid recovered as a result is recycled to the chlorine dioxide generating step. The metathesis is effected by contacting the crystalline sodium sesquisulfate with aqueous sodium chlorate solution, aqueous sodium chloride solution, aqueous methanol or water alone. The metathesis is effected in such manner as to minimize the additional evaporative load imposed on the chlorine dioxide generating process by the metathesis medium.

Abstract: An improved process for treating spent alkylation acid to recover a sulfuric acid product suitable for use in wet process phosphoric plants particularly those which recover uranium as a byproduct. The process utilizes heat and agitation to polymerize the liquid, soluble organic impurities normally contained in spent alkylation acid to insoluble, carbonaceous solids. The carbonaceous solids formed are relatively inert in acidic environments, easy to handle and have valuable cation exchange and impurity scavenging properties.

Abstract: Flue gases etc. may contain SO.sub.2 which should be prevented from admission to the atmosphere. SO.sub.2 is oxidized to SO.sub.3 and condensed with steam to H.sub.2 SO.sub.4 -vapors which are condensed in vertical glass tubes cooled from the outside. In principle the condensate is collected near the bottom of the tubes. In the cooling process a mist of very small H.sub.2 SO.sub.4 droplets is formed and tends to escape to the atmosphere. Environmental regulations continually increase the demands on reducing the amount of acid mist escaping. According to the invention an important method to achieve a reduction of the escape of acid mist is to pass the gas leaving each tube through an aerosol filter in gastight connection with the tube top. Such a filter may consist of acid resistant fibres or filaments having a thickness of 0.04-0.7 mm and may be arranged in specified manners to ensure a drop of pressure through below 20 mbar.