Abstract: A process and apparatus for the regeneration of contaminated acid. The process involves cooling the contaminated acid to a lower temperature sufficient to form at least one liquid hydrate of the acid without forming a solid hydrate of the acid, maintaining the contaminated acid at the lower temperature for a time sufficient to form at least one liquid hydrate of the acid and precipitate an amount of the contaminants, separating the precipitated contaminants from the cooled acid, and warming the acid to decompose the liquid hydrate.

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: 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: An ion exchange separation, recovery and regeneration process for the control of iron is disclosed that can replace the conventional bleed stream process used in copper electrowinning. The disclosed process minimizes the loss of cobalt from the electrowinning circuit and can effect a lowering of the total iron concentration in the electrolyte circuit with an associated increase in current efficiency. The process captures the iron as iron(III) on an ion exchange medium containing a plurality of --CH(PO.sub.3 R.sub.2).sub.2 or --C(PO.sub.3 R.sub.2).sub.2 -- groups through which the divalvent metal ions pass. The iron(III) is then reduced with copper(I) to form iron(II) that is freed from the exchange medium, thereby permitting regeneration of the medium.

Abstract: In a fuel injector magnetic core is inserted in the solenoid coil in the box. The fuel feeding passage is provided in the magnetic core. The movable valve body which moves up to the magnetic core magnetically is provided in the box. The valve body has a flow passage which communicates to the feeding passage. The valve body is forced to be pressed by the plate spring so as to be in contact with the valve box so as to close the fuel injection orifice. The check valve is provided on the fuel feeding passage. An air pressure of about 20 to 100 kPa generated in the crank chamber of the engine is applied to fuel in the box through the diaphragm. Fuel is introduced into the fuel injector without pressurization and confined by the check valve, and the fuel is pressurized using air which is not affected very much by the force due to acceleration. Fuel is fed stably even under severe operational conditions, the engine will not stall due to insufficient or excessive feeding of fuel.

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: 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: In the process, used sulfuric acid which contains, as minor constituents, methylsulfuric acid, dimethyl ether, methanol, aliphatic and olefinic hydrocarbons, chlorinated hydrocarbons and oligomeric siloxanes, in a first step;(1) used sulfuric acid is diluted by introducing steam and optionally by adding liquid water to a concentration of at most 55% by weight sulfuric acid and is heated to boiling at a maximum of 135.degree. C. and in a second step;(2) the sulfuric acid from the first step is reacted with an oxidizing agent at a temperature of from 20.degree. C. to 130.degree. C.

Abstract: The invention relates to a process of producing chlorine dioxide comprising the steps of reducing chlorate ions in an acid reaction medium maintained in a reaction zone of a chlorine dioxide generator, which reaction medium contains alkali metal ions and sulfate ions, so to form chlorine dioxide and a solid salt of acidic alkali metal sulfate.

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: A method of recycling and purifying cleaning chemicals used in the production of semiconductor circuits and containing hydrofluoric acid and or hydrochloric acid. Recycling of such chemicals is accomplished using separation and reconstitution steps Hydrofluoric acid and hydrochloric acid cannot be distilled directly from a chemical solution as they form azeotropes with water. A low vapor pressure substance such as sulfuric acid or phosphoric acid is used to break the azeotrope while increasing the purity of the recovered chemicals and decreasing disposal problems. The method is useable at the point of use of the chemicals.

Abstract: A process for increasing throughput in a spent sulfuric acid dissociation furnace by injecting dewatered biosolids pre-conditioned to enhance combustion into the furnace while enriching the oxygen content of the air used in the process.

Abstract: A process for concentrating a waste sulphuric acid stream containing metal sulphates including iron sulphate comprises the steps of subjecting the stream to an ion exchange operation to produce an acid-rich stream and a salt-rich stream and, concentrating the acid-rich stream to produce a concentrated sulphuric acid stream.

Abstract: An ion exchange separation, recovery and regeneration process for the control of iron has been developed to replace the conventional bleed stream process used in copper electrowinning. The process minimizes the loss of cobalt from the electrowinning circuit and strips the iron into a sulfate-based solution suitable for leach solution makeup. In addition, this process can effect a lowering of the total iron concentration in the electrolyte circuit with an associated increase in current efficiency.

Abstract: The improved method achieves effective and economical decomposition of hydrogen peroxide and may be used in recycling hydrogen peroxide-containing spent sulfuric acid that has been used in wafer cleaning and other operations in the process of semiconductor fabrication or in removing residual hydrogen peroxide that will occur either within the papermaking process or in plant effluents as a consequence of a shift from chlorine-containing bleaching agents to oxygen-containing bleaching agents.When coke was added in an amount of 10 wt % to a solution of 0.88 wt % hydrogen peroxide in 72.6 wt % sulfuric acid, followed by treatment at 60.degree.-70.degree. C. for 4 hours, the concentration of hydrogen peroxide dropped to 0.0001 wt % and below. When coke was added in an amount of 10 wt % to each of a solution (pH, 0.94) of 1.0 wt % hydrogen peroxide in 1.1 wt % sulfuric acid and a solution (pH, 2.58) of 1.04 wt % hydrogen peroxide in sulfuric acid followed by treatment at 60.degree.-70.degree. C.

Abstract: Using generated active intermediates or species simultaneously to remove water and organic compounds from the spent sulfuric acid catalyst of the alkylation of olefins and alkanes is disclosed in this invention. Over 90% water and 95% organic compounds of the spent catalyst can be removed by this invention under mild operating conditions, less than 20 atms and in the temperature range from -50.degree. to 250.degree. C. This invention provides a novel process instead of the traditional or commercial process by combustion and treatment of the spent catalyst at high temperature. It is significant to simplify comparing with the traditional process, and is a safe, simple, clean or pollutionless, and cheap one-stage process.

Abstract: A process for recycling waste sulfuric acid by decomposing organic contaminants by use of light energy, comprising exposing a waste sulfuric acid containing contaminants to a focused radiation emission having an irradiation intensity within the range of from 0.01 to 100 MW/m.sup.2 in a reaction chamber shaped as a directly-absorbing receiver, wherein the chamber is maintained at a temperature within the range of from 200.degree. C. to 1000.degree. C. to form sulfur trioxide and water as sulfuric acid decomposition products. The process also includes forming sulfur dioxide and oxygen, starting materials for sulfuric acid, by cleavage of the decomposition product sulfur trioxide by maintaining the reaction chamber at a temperature between 400.degree. C. and 1500.degree. C. The process, particularly adapted for irradiations with direct solar radiation.

Abstract: The invention concerns a process for purifying sulphuric acid, particularly after it has acted as a catalyst in aliphatic alkylation reactions.It is characterized in that the sulphuric acid is impregnated into a porous organic or inorganic support, for example silica, and is then calcined at least once to eliminate organic hydrocarbon substances which the sulphuric acid may contain.

Abstract: The invention relates to an improved method and a novel apparatus for the concentration, separation, and purification of contaminated chemical compounds, wherein the chemical compound is less volatile than the contaminant. The distillation is performed using constant, predetermined distillation parameters.

Abstract: A high efficiency batch sulfuric acid reprocessor system that is capable of producing high purity acid through distillation. Methods of use are also provided. The distillation is monitored and controlled in accordance with temperatures of the system, in particular, the temperature of the column and the temperature of the vapor in a condensing chamber. A stream splitter enables the invention to selectively collect high purity product as well as remove waste or recycle condensate as reflux.

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 method for separating aluminum, cobalt, and nickel ions contained in a sulfuric acid aqueous solution comprising the steps of (a) contacting a first water-immiscible organic solution containing a first extractant with the sulfuric acid aqueous solution for a period of time to selectively extract the Co ions into the first water-immiscible organic solution so as to obtain a Co-containing first organic phase and a first raffinate aqueous phase containing substantially no Co ions; (b) separating the Co-containing first organic phase from the first raffinate aqueous; (c) contacting a second water-immiscible organic solution containing the first extractant and a second extractant with the first raffinate aqueous solution for a period of time to selectively extract Ni ions into the second water-immiscible organic solution so as to obtain a Ni-containing second organic phase and a second raffinate aqueous phase containing substantially only Al ions; (d) separating the Ni-containing second organic phase from the se

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 present invention provides a process for recovering arsenic acid from a starting mixture comprising sulfuric and arsenic acids and water. In step (a), the starting mixture is treated with a sulfur (IV) compound which will reduce the arsenic acid to arsenic (III) compound under conditions sufficient to substantially convert the arsenic acid to arsenic (III) wherein the resulting mixture comprises arsenic (III) compound, the sulfur (IV) compound, sulfuric acid, and water. In step (b), the resulting mixture is purged with gas to substantially remove the sulfur (IV) compound from the mixture wherein the purged mixture comprises the arsenic (III) compounds, sulfuric acid, and water. In step (c), the purged mixture is treated under conditions sufficient to substantially separate the arsenic (III) compounds from the purged mixture.

Abstract: The present invention is concerned with a method for selectively removing antimony and bismuth from an impure sulphuric acid solution containing at least 50 g/L of acid and some concentration of ferric ion (for example copper refinery electrolyte), is disclosed. The method involves contacting the impure solution with a sufficient quantity of finely divided metallic copper so as to prereduce all ferric ion present in the solution to the ferrous oxidation state. The prereduced solution is then contacted with a chelating resin. The method avoids the deleterious loading of ferric iron onto the ion exchange resin and prevents the return of excessive amounts of chloride ion with the purified electrolyte.

Abstract: Aluminum sulfate that is less colored is prepared by adjusting the concentration of hydrogen peroxide in sulfuric acid to 0.1% by weight or less, and contacting the sulfuric acid with an alumina-containing compound.

Abstract: The improved method achieves effective and economical decomposition of hydrogen peroxide and may be used in recycling hydrogen peroxide containing spent sulfuric acid that has been used in wafer cleaning and other operations in the process of semiconductor fabrication or in removing residual hydrogen peroxide that will occur either within the papermaking process or in plant effluents as a consequence of a shift from chlorine-containing bleaching agents to oxygen-containing bleaching agents.When coke was added in an amount of 10 wt % to a solution of 0.88 wt % hydrogen peroxide in 72.8 wt % sulfuric acid, followed by treatment at 60.degree.-70.degree. C. for 4 hours, the concentration of hydrogen peroxide dropped to 0.0001 wt % and below. When coke was added in an amount of 10 wt% to each of a solution (pH, 0.94) of 1.0 wt % hydrogen peroxide in 1.1 wt % sulfuric acid and a solution (pH, 2.58) of 1.04 wt % hydrogen peroxide in sulfuric acid followed by treatment at 60.degree.-70.degree. C.

Abstract: A process for the reduction in fluoride concentration in a fluoride-contaminated sulphuric acid which process comprises treating said sulphuric acid with a silicon compound to produce silicon tetrafluoride, and removing said silicon tetrafluoride to produce a purer sulphuric acid having a substantially reduced fluoride concentration. The process is of particular use for the removal of fluoride from waste sulphuric acid in the copper smelting industry to meet environmental concerns.

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: 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: The process of concentrating a dilute sulfuric acid in a three-stage vacuum evaporation plant includes feeding an entry dilute sulfuric acid to a first evaporation stage of a vacuum evaporation plant to form an overhead vapor (6), withdrawing a finally concentrated sulfuric acid from the third evaporation stage (3), using steam or the overhead vapor (6) of the first evaporation stage as a heating fluid in the three-stage vacuum evaporation plant, maintaining the entry dilute sulfuric acid under a pressure of 0.4 to 0.7 bar and at a temperature of 80.degree. to 120.degree. C. in the first evaporation stage (1), maintaining the partially concentrated sulfuric acid under a pressure of 0.02 to 0.06 bar and at a temperature of 50.degree. to 90.degree. C. in the second evaporation stage (2), maintaining the further concentrated sulfuric acid under a pressure of 0.02 to 0.06 bar and at a temperature of 80.degree. to 120.degree. C.

Abstract: Polychlorinated waste materials such as polychlorinated dibenzodioxines (PCDD), polychlorinated dibenzofuranes (PCDF) and polychlorinated biphenyls (PCB) are subjected to nonpolluting destruction by combusting said materials together with waste sulfuric acids, acid tars and similar sulfur- and carbon-containing waste products of various compositions and consistencies in a multi-stage combustion furnace.

Abstract: Method for the production of ultrapure sulfuric acid including distillation of sulfuric acid material for the removal of soluble impurities and insoluble and non-volatile particles of 10 microns to 0.2 micron or less in size. Reprocessing is also provided. Distillation takes place in a distillation chamber having walls which are provided with means within the chamber to provide smooth convective upward flow of distilling liquid and vapor proximate the walls and means for smooth convective downward flow substantially centrally of the distillation chamber. Redirection means and packing together with reflux means insure the washing of rising vapor and direct the condensing vapor substantially centrally of the distillation chamber. Ultrapure sulfuric acid is also provided having 5 or less particles per cubic centimeter of a size of 0.5 micron and larger and less than 10 ppb of any specific trace impurity such as cations.

Abstract: A process for reprocessing sulfuric acid obtained in the purification of yellow phosphorous, which comprises mixing the contaminated sulfuric acid with hydrogen peroxide and reacting this mixture in a vessel containing hot concentrated sulfuric acid at 110.degree. to 210.degree. C. in the presence of FeSO.sub.4, MnSO.sub.4 or NiSO.sub.4 as a catalyst is described.

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: A process for the recovery of sulphuric acid from a waste acid stream containing ammonium sulphate comprising vaporizing the waste acid and subsequently converting the ammonia and sulphur dioxide generated to nitrogen and sulphur trioxide, respectively. The process provides an economic method for the regeneration of the waste sulphuric acid from a methyl methacrylate production process.

Abstract: Dilute waste sulfuric acid is concentrated by heating it against product acid and then passing it through two contact zones separated by a collection zone. The dilute acid scrubs vapour produced in the collection zone and from a high temperature acid reboiler. In the collection zone acid is drawn off, heated, and recirculated to the collection zone where part of the liquid flashes to vapour. The main heat input is to the more dilute low temperature recirculating acid from the first contact zone rather than to the more concentrated high temperature acid in the reboiler. As a result, less sulfuric acid vapour is generated; the major portion of the heat can be fed to the process at low temperature; and only a single column is required, having a single cool clear water vapour exit stream to dispose of.

Abstract: A process for the recovery of sulphuric acid from waste acids containing metal sulphates by evaporative concentration and separation of the metal sulphates from the suspension obtained by evaporation, the improvement wherein vapors leaving the evaporators together with droplets of sulphuric acid containing metal sulphates and solid metal sulphates are condensed by direct contact with cooled contaminated vapor condensate, cooling of this vapor condensate which is circulated as cooling medium is carried out in a flash evaporator and the vapors leaving the flash evaporator free from metal sulphates and sulphuric acid are directly or indirectly condensed by means of cooling agent.

Abstract: An apparatus and method for reprocessing waste piranha containing contaminated H.sub.2 SO.sub.4 from, for example, a semiconductor processing operation is described. The apparatus and method include a first distillation flask which is maintained under a substantial vacuum. The first distillation flask includes a first column packed with a column packing material and an input pipe for refluxing to retard loss of H.sub.2 SO.sub.4 in the first distillation. The second distillation flask boils off substantially pure H.sub.2 SO.sub.4 and provides for a continuous automatic purge of the contaminants from the second distillation flask thus improving the purity of the H.sub.2 SO.sub.4. The substantially pure H.sub.2 SO.sub.4 flows through a column which is coupled to a condenser which condenses substantially pure H.sub.2 SO.sub.4.

Abstract: Apparatus for the manufacture of sulphuric acid by the contact process of the type comprising at least one gas-concentrated sulphuric acid contacting unit and a sulphuric acid heat exchanger characterized in that the contacting unit and/or heat exchanger is formed of high silicon content austenitic steel. The steel is also of use in sulphuric acid concentrations. Reduced corrosion rates are provided.

Abstract: Contaminants in spent nitric-sulfuric nitration acid can be removed by mixing the spent acid with urea and heating to 75.degree.-150.degree. C. Off-gas from the spent acid/urea reaction is passed through a Group IB, VB, VIB or VIII metal containing catalyst to decompose nitrous oxides and the so-treated off-gas is contacted with spent acid, denitrated spent acid, or fresh sulfuric acid, and optionally air (i.e. oxygen), to absorb oxides of nitrogen. The spent acid scrubbing fluid is then subjected to the same process for removing contaminants.

Abstract: In flue gases or other humid exhaust gases which contain NO.sub.x and SO.sub.2, the NO.sub.x content is reduced and the SO.sub.2 content is oxidized to SO.sub.3 by a catalytic processing and the SO.sub.3 content is subsequently condensed as sulfuric acid. In order to prevent a clogging and deterioration of the catalyst and a contamination of the sulfuric acid the flue gas is subjected before the catalytic processing to a fine dedusting by a scrubbing with hot dilute sulfuric acid. In dependence on the water content of the flue gases the concentration of sulfuric acid in the dilute sulfuric acid and the temperature of the latter are adjusted so that no water will be transferred from the flue gases to the dilute sulfuric acid and no water or only a small amount of water will be transferred from the dilute sulfuric acid to the flue gas.

Abstract: The present invention relates to a method for decoloring sulphuric acid produced in accordance with the contact method, comprising one or more absorption circuits. The produced sulphuric acid is decolored by adding hydrogen peroxide to the system. The method is characterized by adding the hydrogen peroxide to the sulphuric acid in the final absorption circuit, and by maintaining the temperature in this circuit above about 70.degree. C.

Abstract: A method is disclosed for removing iron from iron-contaminated sulfuric acid to render the sulfuric acid suitable for ion membrane processing which comprises contacting the iron-contaminated sulfuric acid with an oxidizing agent to oxidize essentially all of the iron to the +3 oxidation state, contacting the resulting iron-contaminated sulfuric acid containing oxidized iron with a complexing agent which can be citric acid, oxalic acid, and tartaric acid, with the amount of the complexing agent being sufficient to complex essentially all of the oxidized iron, and contacting the resulting iron-contaminated sulfuric acid containing the complexed iron with activated carbon to remove essentially all of the iron and produce a purified sulfuric acid solution.

Abstract: The present invention discloses a process for rejuvenation of strip acid employed in the reclamation of expended lead-acid battery acid through extraction and filtration for removing metallic impurities from the battery acid. In the process of removing impurities from battery acid through extraction, the extractant becomes loaded with impurities and loses its effectiveness. Extractant may be regenerated by contacting it with an strip acid. In the present invention, a reduction process is employed to regenerate the strip acid so that it may be used repeatedly. By recycling the extractant and the strip acid in the present invention, the present process further increases the effectiveness of battery acid regeneration--producing a reclaimed battery acid fluid which performs very well in new batteries and substantially reducing by-product waste in the regeneration of the battery acid.

Abstract: A method and apparatus for the recovery of heat from a sulfuric acid process are provided. Sulfur trioxide is absorbed into hot concentrated sulfuric acid, acid having a concentration greater than 98% and less than 101% and a temperature greater than 120.degree. C., in a heat recovery tower and the heat created by the exothermic reaction is recovered in a useful form in a heat exchanger. Gas leaving the primary heat recovery absorption zone is cooled by contact with sulfuric acid in a secondary absorption and cooling zone located above the primary absorption zone in the tower.

Abstract: An apparatus and method for reprocessing waste piranha containing contaminated H.sub.2 SO.sub.4 from, for example, a semiconductor processing operation is described. The apparatus and method include a first distillation flask which are maintained under a substantial vacuum. The first distillation flask includes a first column with a column packing means and a reflux means to retard loss of H.sub.2 SO.sub.4 in the first distillation. The second distillation flask boils off substantially pure H.sub.2 SO.sub.4 through a column which is coupled to a condenser which condenses substantially pure H.sub.2 SO.sub.4.

Abstract: The present invention discloses a process of extraction and filtration for removing metallic impurities from the acid in used lead-acid batteries. Produced is a reclaimed battery acid fluid which performs very well in new batteries and which avoids the severe costs and environmental risks entailed in present methods of battery acid fluid disposal.