And A Nitrogenous Or Carbonaceous Compound Patents (Class 423/479)
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Patent number: 8282891Abstract: The instant application provides apparatus and methods for the generation of gas, preferably chlorine dioxide. The methods and apparatus of the invention use a removable reaction chamber for the reaction of precursor chemicals, e.g., chlorite salt and an acid. The methods and compositions of the invention provide gas for a number of personal and commercial applications.Type: GrantFiled: July 1, 2010Date of Patent: October 9, 2012Assignee: TBS Technologies, LLCInventors: Thomas J. Dee, Paul Sabin, Douglas Sabin
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Publication number: 20120244063Abstract: Disclosed is a process for the production of chlorine dioxide, by which sulphuric acid can be efficiently mixed into the reaction mixture. The process apparatus includes a reaction vessel (1) operating in reduced pressure, in which alkali metal chlorate is reduced in acidic conditions. The reaction vessel (1) is equipped with a recirculation line (2) of the reaction mixture, including a circulation pump (3) and, downstream after the pump, a heat exchanger (4). The process is characterized in that the sulphuric acid is fed into the recirculation line (2) before the circulation pump, or into the circulation pump (3).Type: ApplicationFiled: October 29, 2010Publication date: September 27, 2012Applicant: KEMIRA OYJInventor: Seppo Pohjanvesi
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Publication number: 20120201740Abstract: The present invention relates to a process for production of chlorine dioxide comprising: reacting in an acidic reaction medium in a reaction vessel an alkali metal chlorate or chloric acid and methanol to generate chlorine dioxide, withdrawing from the reaction vessel a gas comprising chlorine dioxide and gaseous by-products, condensing part of the gas withdrawn to obtain a condensate; and removing the condensate from the non-condensed gas without re-circulating it back to the process for production of chlorine dioxide.Type: ApplicationFiled: October 7, 2010Publication date: August 9, 2012Applicant: AKZO NOBEL CHEMICALS INTERNATIONAL B.V.Inventors: Anders Dahl, Kalle Hans Thomas Pelin
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Publication number: 20120156125Abstract: Process for the continuous production of chlorine dioxide comprising generating chlorine dioxide in an aqueous reaction medium in a reaction vessel (1) maintained at sub-atmospheric pressure, bringing gaseous chlorine dioxide from said reaction vessel to an absorption tower (7) and contacting it therein with a flow of water to form an aqueous solution containing chlorine dioxide, bringing said aqueous solution containing chlorine dioxide to a stripper (12), blowing a gas through said aqueous solution of chlorine dioxide in the stripper to strip off from 10 to 100% of the chlorine dioxide entering the stripper and form a gaseous chlorine dioxide product.Type: ApplicationFiled: June 11, 2010Publication date: June 21, 2012Applicant: AKZO NOBEL N.V.Inventors: Kalle Hans Thomas Pelin, Nils Torgny Björkman
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Patent number: 8168153Abstract: The invention concerns a process for the production of chlorine dioxide comprising generating chlorine dioxide in an aqueous reaction medium in a reaction vessel maintained at super-atmospheric pressure, withdrawing gaseous chlorine dioxide from said reaction medium, bringing withdrawn gaseous chlorine dioxide to an aqueous absorption medium and withdrawing gaseous chlorine dioxide from said absorption medium.Type: GrantFiled: July 11, 2008Date of Patent: May 1, 2012Assignee: Akzo Nobel N.V.Inventors: John C. Sokol, Michael Burke
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Publication number: 20110176989Abstract: A process for chlorine dioxide production uses waste glycerol from biodiesel plants as a reducing agent. This untreated waste stream may contain other reducing agents such as sodium chloride and methanol which were found to enhance the chlorine dioxide production. Other chemicals present in this waste stream did not affect the operation of the chlorine dioxide generator. Substituting the waste glycerol for methanol or other reducing agents helps kraft pulp mills in reducing the cost of producing chlorine dioxide while providing a use for the untreated waste glycerol stream.Type: ApplicationFiled: September 22, 2009Publication date: July 21, 2011Inventors: Naceur Jemaa, Michael Paleologou
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Patent number: 7645436Abstract: Tractable metal oxide sols are made by combining at least one metal oxide compound, at least one organofunctional silane, at least one boron oxide compound, and a liquid, or metal oxide sols are made by combining at least one metal oxide compound, at least one organofunctional silane, at least one of an acid catalyst and salt/complex catalyst, and a liquid. Also disclosed are nanocomposites containing the metal oxide sols and at least one of metal nanoparticle, metal-chalcogenide nanoparticle, metal oxide nanoparticle, and metal phosphate nanoparticle. Further disclosed are composites containing a polymer material and at least one of the metal oxide sol and the nanocomposite.Type: GrantFiled: April 12, 2006Date of Patent: January 12, 2010Assignee: APS LaboratoryInventor: Hong-Son Ryang
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Patent number: 6921521Abstract: A method of producing chlorine dioxide (ClO2) is described which employs Urea as a reducing agent to reduce alkaline chlorate (NaClO3 or KClO3) in a mineral acid medium. The method of the invention can, for example, by means of a very high transfer rate, be used to reduce over 90% of the reactant, alkaline chlorate, to the product, chlorine dioxide. Furthermore, ClO2 product purity is accomplished, for example, over 95%. The mother solution of the reaction can then be processed, for example, to produce other useful inorganic salts, including potassium sulfate, potassium nitrate, sodium nitrate, and the like, and/or compound fertilizer resulting in useful chemical products rather than toxic waste. Accordingly, the method of the invention provides for efficient, cost effective, and safe production of ClO2 as well as inorganic salts and/or compound fertilizer.Type: GrantFiled: October 15, 2003Date of Patent: July 26, 2005Inventors: TianLang Chen, YaoPing Wu, ShenXiu Xiao
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Publication number: 20040131534Abstract: A method of producing chlorine dioxide (ClO2) is described which employs Urea as a reducing agent to reduce alkaline chlorate (NaClO3 or KClO3) in a mineral acid medium. The method of the invention can, for example, by means of a very high transfer rate, be used to reduce over 90% of the reactant, alkaline chlorate, to the product, chlorine dioxide. Furthermore, ClO2 product purity is accomplished, for example, over 95%. The mother solution of the reaction can then be processed, for example, to produce other useful inorganic salts, including potassium sulfate, potassium nitrate, sodium nitrate, and the like, and/or compound fertilizer resulting in useful chemical products rather than toxic waste. Accordingly, the method of the invention provides for efficient, cost effective, and safe production of ClO2 as well as inorganic salts and/or compound fertilizer.Type: ApplicationFiled: October 15, 2003Publication date: July 8, 2004Inventors: TianLang Chen, YaoPing Wu, ShenXiu Xiao
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Publication number: 20030000068Abstract: Method for producing a sputtering target with a lowered oxygen content by providing an alloy selected from the group consisting of NiFe, CoCrPt, CoCrPtB, CoPt, PtMn, FeAlSi, FeCo, and FeMn; adding an oxygen scavenger element to the molten alloy selected from the group consisting of Group 4A, 3B and 4B elements; melting the alloy and the oxygen scavenger; reacting the oxygen scavenger element with oxygen in the melt to reduce the oxygen content of the alloy to a level of not more than 50 ppm and achieving a residual oxygen scavenger element content of not more than 100 ppm.Type: ApplicationFiled: August 28, 2002Publication date: January 2, 2003Applicant: Mitsui Mining & Smelting Co., Ltd.Inventors: Satoru Kobayashi, Yoshihiro Sera, Norioki Ikeda, Masato Imamura, Shuji Shihara, Hiroyuki Sakai
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Production of chlorine dioxide by chemical reduction of ammonium chlorate in aqueous acidic solution
Patent number: 6287533Abstract: A novel method is described whereby chlorine dioxide is produced through the chemical reduction of ammonium chlorate in an aqueous acidic solution. The reduction reaction takes place at elevated temperatures with or without a catalyst. The reducing agent of this reaction is preferably hydrogen peroxide, glycerol, or sucrose. Chlorine dioxide may be produced in accordance with this invention at a substantially higher rate and in higher yield than with conventional methods using sodium chlorate. Further, the chlorine dioxide produced is substantially chloride-free. The ammonium sulfate by-product of this method has direct use as a fertilizer.Type: GrantFiled: January 13, 2000Date of Patent: September 11, 2001Inventors: Mohammed N. I. Khan, M. Fazlul Hoq -
Patent number: 5770171Abstract: A process for production of chlorine dioxide which is substantially free of by product chlorine. Chlorine-dioxide is produced from an alkali metal chlorate, a mineral acid and a reducing agent such as methanol in a reaction medium maintained at an acid normality of less than 9 and with a high chlorate molarity. The process is carried out in the substantial absence of additional chloride ion being fed to the process. It has been found that increasing the chlorate concentration at a given acid normality reduces the amount of chloride in the reaction medium thus reducing the amount of chlorine by-product. The process is carried out in a vessel operated under subatmospheric pressure, whereby water is evaporated and withdrawn together with chlorine dioxide and the alkali metal salt of the mineral acid is crystallized within the reaction vessel and withdrawn therefrom.Type: GrantFiled: March 5, 1990Date of Patent: June 23, 1998Assignee: Eka Nobel Inc.Inventors: Birgitta Sundblad, Anders Oscar Johan Dahl, John R. Winters
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Patent number: 5593653Abstract: Sodium sesquisulfate produced in crystalline form in a high acidity 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.Type: GrantFiled: August 23, 1994Date of Patent: January 14, 1997Assignee: Sterling Canada, Inc.Inventors: Herbert C. Scribner, Maurice C. J. Fredette, Edward J. Bechberger, Chunmin Pu
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Patent number: 5378447Abstract: A process is disclosed for producing a dilute solution of an alkali or alkaline earth metal chlorate from a chlorine and carbon dioxide waste gaseous stream. The process of the invention can be combined in a continuous process for the production of an alkali or alkaline earth metal chlorate for use in a chlorine dioxide generator for the production of chlorine dioxide in which the waste gaseous stream from the chlorine dioxide generator is converted to a dilute solution of an alkali or alkaline earth metal chlorate and passed to an electrochemical cell for the generation of an alkali or alkaline earth metal sodium chlorate, the product of the electrochemical cell being in turn passed to the chlorine dioxide generator.Type: GrantFiled: November 8, 1993Date of Patent: January 3, 1995Assignee: Huron Tech Corp.Inventors: John R. Jackson, Charles L. Pitzer, Charles O. Buckingham
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Patent number: 5376350Abstract: A plug flow process for the production of chlorine dioxide by reacting chloric acid and/or an alkali metal chlorate, optionally a mineral acid and a reducing agent in such proportions that chlorine dioxide is produced. Reactants are continuously fed to a plug flow reactor under conditions that chloride dioxide is produced as the reactants flow through the reactor. The process stream has an acidity between 2N and 11N. The process stream is subjected to superatmospheric pressure in the reactor sufficient to maintain the formed chlorine dioxide in solution. After removal of the chlorine dioxide from the process stream exiting the plug flow reactor, the process stream can optionally be fed to a second chlorine dioxide generator for further reaction.Type: GrantFiled: December 10, 1992Date of Patent: December 27, 1994Assignee: Eka Nobel ABInventors: Joel D. Tenney, John R. Winters
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Patent number: 5154910Abstract: A process for the production of essentially chlorine free chlorine dioxide whereby a flow of chlorine dioxide obtained from reduction of alkali metal chlorate and containing by-product of chlorine gas is absorbed in water and the chlorine gas is treated with formic acid in the water solution. The formic acid is added in an amount resulting in a mole ratio formic acid to chlorine gas of >1:1.Type: GrantFiled: June 27, 1991Date of Patent: October 13, 1992Assignee: Eka Nobel ABInventor: Jorgen Engstrom
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Patent number: 5110581Abstract: A process for the generation of chlorine dioxide from an alkali metal chlorate is provided that employs a waste sulphuric acid containing oxidizable organic material. Alkylation waste sulphuric acid from petroleum refining is particularly useful in this process. Conventional chlorate reducing agents used in the generation of chlorine dioxide can be partially or completely replaced by the organic material contained in the alkylation waste acid.Type: GrantFiled: October 1, 1990Date of Patent: May 5, 1992Assignee: Marsulex Inc.Inventor: Russell I. Derrah
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Patent number: 5093097Abstract: A process for the production of chlorine dioxide by reacting in a reaction vessel an alkali metal chlorate, mineral acid and a reducing agent in such proportions that chlorine dioxide is produced in a reaction medium which is maintained at a temperature of from about 50.degree. C. to about 100.degree. C. and at an acidity within a range of from about 2 to about 11N and which is subjected to subatmospheric pressure sufficient for evaporating water. A mixture of chlorine dioxide and water vapor is withdrawn from an evaporation zone in the reaction vessel, and alkali metal sulfate is precipitated in a crystallization zone in the reaction vessel. Straight chained alcohols with the formula CH.sub.2 OH(CHOH).sub.n CH.sub.2 OH where n=0-5, are used as reducing agents. Preferred reducing agents consist of glycol or glycerol. The reaction may also be performed in the presence of a catalyst.Type: GrantFiled: October 9, 1990Date of Patent: March 3, 1992Assignee: Eka Nobel ABInventors: Jorgen Engstrom, Birgitta Sundblad
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Patent number: 5066477Abstract: Chlorine dioxide is produced from sodium chlorate, sulphuric acid and methanol at the boiling point of the reaction medium under a subatmospheric pressure applied to a reaction zone. High purity of chlorine dioxide production is retained while the proportion of acid sodium sulphate in the product is decreased by effecting the reaction at high acidity in a physically-separate reaction zone from which the reaction products discharge into a mass of recycling sodium chlorate solution.Type: GrantFiled: September 18, 1990Date of Patent: November 19, 1991Assignee: Tenneco Canada Inc.Inventors: Michael S. Zell, Maurice C. J. Fredette
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Patent number: 5002746Abstract: The present invention relates to a process for production of chlorine dioxide by reacting in a reaction vessel an alkali metal chlorate, a mineral acid and methanol as a reducing agent in proportions to generate chlorine dioxide in a reaction medium maintained at a temperature from about 50.degree. C. to about 100.degree. C. and an acidity within the interval from a b out 2 to 4.8 N and subjected to a subatmospheric pressure sufficient to effect evaporation if water. A mixture of chlorine dioxide and water vapor is withdrawn from an evaporation region in the reaction vessel and an alkali metal salt of the mineral acid is precipitated in a crystallization region in the reaction vessel.Type: GrantFiled: June 28, 1989Date of Patent: March 26, 1991Assignee: Eka Nobel ABInventor: Maria Norell
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Patent number: 4986973Abstract: A process for producing chlorine dioxide by reacting in a reaction vessel an alkali metal chlorate, mineral acid and a reducing agent in such proportions that chlorine dioxide is produced in a reaction medium maintained at a temperature of from about 50.degree. C. to about 100.degree. C. and at an acidity within a range of from about 2 to about 11 N. The reaction medium is subjected to subatmospheric pressure sufficient for evaporating water, a mixture of chlorine dioxide and water vapor being withdrawn from an evaporation zone in the reaction vessel and alkali metal sulfate being precipitated in a crystallization zone in the reaction vessel. A mixture of formaldehyde and methanol is used as reducing agent.Type: GrantFiled: October 26, 1989Date of Patent: January 22, 1991Assignee: Eka Nobel ABInventors: Bjorn H. Svedin, Birgitta Sundblad, Jorgen Engstrom
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Patent number: 4978517Abstract: A process for production of chlorine dioxide by reacting in a reaction vessel an alkali metal chlorate, a mineral acid and methanol as a reducing agent in proportions to generate chlorine dioxide in a reaction medium maintained at a temperature from about 50.degree. C. to about 100.degree. C. and at an acidity within the interval from about 2 to about 11N and subjected to an subatmospheric pressure. Thereby water is evaporated and a mixture of chorine dioxide, water vapor and gaseous by-products is withdrawn from an evaporation region in the reaction vessel. The alkali metal sulphate is precipitated in a crystallization region in the reaction vessel. The content of formic acid in the reaction vessel is increased by addition of formic acid to a content of formic acid exceeding about 0.3M. The gaseous by-products are condensed to obtain formic acid and the content of formic acid in the reaction vessel is increased by recirculation of the condensate.Type: GrantFiled: February 28, 1989Date of Patent: December 18, 1990Assignee: Eka Nobel ABInventors: Maria Norell, Bjorn H. Svedin
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Patent number: 4961918Abstract: The present invention relates to a process for production of chlorine dioxide by reacting in a reaction vessel an alkali metal chlorate, sulfuric acid and methanol as a reducing agent. A reaction medium is maintained at a temperature from about 50.degree. C. to about 100.degree. C. and is subjected to a subatmospheric pressure sufficient to effect evaporation of water whereby a mixture of chlorine dioxide and water vapor is withdrawn from an evaporation region in the reaction vessel and alkali metal sulfate is precipitated in a crystallization region in the reaction vessel. Raw methanol purified by separation and adsorption is used as reducing agent. The raw methanol is purified by dilution with water whereby an unpolar phase is separated and and the remaining methanol-water phase is contacted by an adsorbing agent. The adsorbing agents used can be zeolites, active carbon or polymer adsorbing agents.Type: GrantFiled: February 15, 1989Date of Patent: October 9, 1990Assignee: Eka Nobel ABInventors: Maria Norell, Anders Dahl, Ursula Soderberg
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Patent number: 4931268Abstract: Chlorine dioxide is generated at high efficiency from feeds of chlorate cell liquor, sulphuric acid and methanol by a hybrid of reaction of sodium chlorate with sulphuric acid and methanol and reaction of sodium chlorate with sulphuric acid and sodium chloride. The reaction medium is maintained at its boiling point under a subatmospheric pressure while sodium sesquisulphate precipitates from the reaction medium.Type: GrantFiled: August 28, 1989Date of Patent: June 5, 1990Assignee: Tenneco Canada Inc.Inventors: Maurice C. J. Fredette, Ching-Shi Yang
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Patent number: 4929434Abstract: A process for producing chlorine dioxide by reducing a chlorate in sulphuric acid of at least 4N with a reducing agent. An oxygen containing organic compound is introduced into the process.Type: GrantFiled: March 9, 1989Date of Patent: May 29, 1990Inventors: Derek G. Lobley, Kenneth Pinder
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Patent number: 4770868Abstract: The present invention relates to a process for production of chlorine dioxide from an alkali metal chlorate, a mineral acid and a volatile reducing agent. The process is carried out in a vessel operated under subatmospheric pressure, whereby water is evaporized and withdrawn together with chlorine dioxide and the alkali metal salt of the mineral acid is crystallized within the reaction vessel and withdrawn therefrom. According to the invention the utility of the volatile reducing agent is enhanced by the addition of the agent to the region of crystallization in the reaction vessel.Type: GrantFiled: June 12, 1987Date of Patent: September 13, 1988Assignee: EKA Nobel ABInventor: Maria Norell
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Patent number: 4609472Abstract: A process for removing chlorate ions from an impure alkali metal chloride brine removed from an electrolytic cell comprises acidifying the impure brine to a pH of less than about 2. The acidified brine is then reacted with a reducing portion of hydrazine hydrochloride.The novel process rapidly reduces the chlorate ions in the absence of the formation of chlorine and chlorine dioxide gases and with the production of nitrogen gas as a product.Type: GrantFiled: March 29, 1985Date of Patent: September 2, 1986Assignee: Olin CorporationInventors: Don E. Reynolds, James D. Kilby
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Patent number: 4578261Abstract: A method of generating chlorine dioxide that comprises forming chloric acid by the action of sulphuric acid on a chlorate in a generator in the liquid phase. The chloric acid is reduced to produce chlorine dioxide. The chlorate is fed to the generator as a solid slurry.Type: GrantFiled: November 28, 1984Date of Patent: March 25, 1986Assignee: Multifibre Process LimitedInventor: Derek G. Lobley
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Patent number: 4486399Abstract: A method of generating chlorine dioxide that comprises forming chloric acid by the action of sulphuric acid on a chlorate in a generator in the liquid phase. The chloric acid is reduced to produce chlorine dioxide. The chlorate is fed to the generator as a solid.Type: GrantFiled: July 1, 1983Date of Patent: December 4, 1984Assignee: Multifibre Process LimitedInventor: Derek G. Lobley
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Patent number: 4473540Abstract: Chlorine dioxide is formed at high efficiency from a solution of acid sodium chlorate at high sulphuric acid normality to which methanol is fed. The reaction medium is at its boiling point under a subatmospheric pressure. Total acid normality values in the range of about 7 to about 9 normal may be used while high efficiency of chlorine dioxide production is maintained.Type: GrantFiled: July 7, 1983Date of Patent: September 25, 1984Assignee: ERCO Industries LimitedInventor: Maurice C. J. Fredette
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Patent number: 4465658Abstract: Chlorine dioxide is formed at high efficiency from a solution of acid sodium chlorate at high sulphuric acid normality in excess of 9 normal to which methanol is fed. The reaction medium is at its boiling point under a subatmospheric pressure. The incidence of white-outs is avoided by feeding chloride ions to the reaction medium, while the efficiency of chlorine dioxide production remains high.Type: GrantFiled: June 13, 1983Date of Patent: August 14, 1984Assignee: Erco Industries LimitedInventor: Maurice C. J. Fredette
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Patent number: 4325934Abstract: A highly efficient chlorine dioxide generating process which produces chlorine-free chlorine dioxide and neutral solid phase sodium sulphate from sodium chlorate, sulphuric acid and methanol is described. Solid phase sodium acid sulphate recovered from the high acidity reaction medium is metathesized using controlled quantities of water and controlled quantities of methanol to form the solid phase neutral sodium sulphate. Sulphuric acid recovered from the acid sulphate by the metathesis is recycled to the generator along with a part of the methanol used in the metathesis.Type: GrantFiled: September 22, 1980Date of Patent: April 20, 1982Assignee: Erco Industries LimitedInventors: Richard Swindells, Maurice C. J. Fredette
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Patent number: 4201687Abstract: A fabric bleaching composition is provided which consists essentially of water and a bleach selected from the group consisting of disodium chloroimidodisulfate, dipotassium chloroimidodisulfate and mixtures thereof. The fabric bleaching composition can also contain a detergent, a buffering agent and other ingredients in a detergent formulation. The fabric bleaching composition is intermediate in strength between peroxide-type fabric bleaches and alkali metal hypochlorite fabric bleaches.Type: GrantFiled: October 25, 1978Date of Patent: May 6, 1980Assignee: Monsanto CompanyInventors: Marvin M. Crutchfield, Robert P. Langguth, James M. Mayer
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Patent number: 4156713Abstract: There is provided an improved process for the production of chlorine dioxide wherein an alkali metal chlorate a reducing agent, and a mineral acid are reacted in a vessel, and the salt crystals are separated from the generator crystal slurry.Type: GrantFiled: September 23, 1977Date of Patent: May 29, 1979Assignee: Hooker Chemicals & Plastics Corp.Inventor: Willard A. Fuller
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Patent number: 4154809Abstract: The efficiency of a low actual hydrogen ion concentration chlorine dioxide producing process in which a chlorate and hydrochloric acid or hydrogen chloride are fed to a reaction medium in a single vessel generator-evaporator crystallizer is increased by the use of small quantities of methanol.Type: GrantFiled: April 4, 1978Date of Patent: May 15, 1979Assignee: Erco Industries LimitedInventors: Richard Swindells, Maurice C. J. Fredette
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Patent number: 4145401Abstract: The efficiency of a low total acid normality chlorine dioxide producing process in which a chlorate, a chloride and sulphuric acid are fed to a reaction medium in a single chambered generator-evaporator-crystallizer vessel is increased by the use of small quantities of methanol.Type: GrantFiled: February 22, 1977Date of Patent: March 20, 1979Assignee: ERCO Industries LimitedInventors: Richard Swindells, Maurice C. J. Fredette
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Patent number: 4115217Abstract: This invention relates to a process for the preparation of chlorite from chlorate.Type: GrantFiled: May 6, 1977Date of Patent: September 19, 1978Assignees: Kemanord AB, Kemanord AB, Kemanord ABInventors: Karl-Georg Larsson, Maria Norell
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Patent number: 4105751Abstract: Chlorine dioxide is manufactured by reducing an alkali metal chlorate in an acid medium by means of a gaseous or liquid reducing agent in at least one production reactor, with recycling of the tail gases to the said reactor, in order to dilute the chloride dioxide produced. In the new process, the tail gases to be recycled are brought into contact with an excess of reducing agent and a sufficient amount of water to reduce virtually all of the chlorine contained in these tail gases to hydrochloric acid, and thereafter the mixture thus obtained, of tail gases after reduction, and of reducing agent, is recycled, at least partly, to the said reactor. In this way, a large amount of chloride ions, which are immediately available for the basic reaction of production of chlorine dioxide, is introduced at the same time as the neutral gases required for dilution.Type: GrantFiled: March 21, 1977Date of Patent: August 8, 1978Assignee: Societe d'Etudes ChimiquesInventor: Alain Caillol