Class 423/394.2 - Purification or recovery

Subclass of Class 423 - Chemistry of inorganic compounds
Definition: Processes wherein the nitric acid is separated from impurities
No. of patents: 23
Last issue date: 12/22/2009

Number	Title	Issue Date
7635459	Method of removing nitric acid from aqueous liquid and method of producing drinks Disclosed is a method of removing nitric acid from an aqueous liquid containing various components such as vegetable extract, and nitrate ion is removed selectively without spoiling the taste or other components, by subjecting the aqueous liquid to chromatographic t...	12/22/2009
6946105	Process and apparatus for the recovery of metal oxide particles A process for the recovery of metal oxides from a solution containing metallic salts by spray roasting of these solutions. The process is particularly suitable for spray roasting spent pickling acids. The process feeds the solution to a reactor for spray roasting of...	09/20/2005
6846418	Process for treating acidic and metallic waste water A process for treating acidic and metallic waste water, particularly the rinsing water and/or used acids from pickling plants. The process includes the step of adding an alkaline solution or gas to bind the free acids in the waste water, followed by separation of th...	01/25/2005
6737034	Nitric acid production A method process to convert inhibited red fuming nitric acid (IRFNA) and/or nitrogen tetraoxide to either dilute or concentrated (98%+) nitric acid. The method describes a process to remove all of the normal inhibitors (if required), that have been reported to been ...	05/18/2004
6508915	Apparatus and method for distilling waste liquids A distilling apparatus and method use a two step distillation and purification process for processing a waste liquid, such as an impure sulfuric acid solution, to form a highly concentrated sulfuric acid solution. First, the waste liquid is stored in a co...	01/21/2003
6375915	Method of regenerating a spent pickling solution In a method of regenerating a spent pickling solution composed of nitric acid and hydrofluoric acid and containing metal fluorides and metal nitrates, the pickling solution is heated in a reactor to about 300-1,000° C., the metal fluorides and the metal ...	04/23/2002
6355223	Closed loop process for producing chlorine from hydrogen chloride A method for oxidizing HCl to produce pure chlorine gas by reacting HCl with a mixture of sulfuric and nitric acids. Chlorine gas is evolved. Spent nitric and sulfuric acids are first regenerated by contact with air or oxygen. After regeneration, the enti...	03/12/2002
6197268	Reduction of toxic substances in waste gas emissions Nitrogen oxides are removed from a waste gas stream by contacting the waste gas stream with ammonia, thereby reducing the nitrogen oxides to nitrogen. Residual nitrogen oxides and unreacted ammonia in the waste gas stream leaving the nitrogen oxides reduc...	03/06/2001
5980850	Process and plant for extraction or recovery of acids from solutions of these acids Process for extraction or recovery of acids, in particular hydrofluoric acid, hydrochloric acid and nitric acid, from solutions of these acids containing metal, by pyrohydrolytic treatment and subsequent absorption and/or condensation of the acid gases th...	11/09/1999
5980753	Process for recovering volatile acids The present invention provides a process for recovering a volatile acid charaterized by bringing a waste liquid containing the volatile acid into contact with an amine having a boiling point of at least 50° C. to thereby cause the amine to tonically adso...	11/09/1999
5632866	Point-of-use recycling of wafer cleaning substances 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 Hydrof...	05/27/1997
5603811	Process for the treatment of an aqueous solution mainly containing nitric acid and hydrofluoric acid A process for treating an aqueous solution mainly containing nitric acid and hydrofluoric acid. The process involves distilling to provide an aqueous solution concentrated in nitric acid and hydrofluoric acid for the separation thereof, then separating by...	02/18/1997
5589037	Method for removing tetranitromethane from nitric acid Tetranitromethane and other polynitrated methanes can be effectively removed from otherwise substantially organic-free nitric acid streams through the addition of substantially organic-free concentrated sulfuric acid and by, optionally, performing seconda...	12/31/1996
5500098	Process for regeneration of volatile acids Volatile acids containing metal salt impurities, such as metal pickling solutions-are regenerated by a process in which the acid is subjected to sulfuric acid distillation. Resulting volatile acid vapor is condensed and recycled to the pickle tank, while ...	03/19/1996
5425800	Recovery of precious metal values from refractory ores A hydrometallurgical process is described for recovery of precious metals from ores refractory to treatment by lixiviating agents by crushing the ore to no finer than a nominal 1/4 inch size, treating the ore with about 100% to about 300% of the stoichiom...	06/20/1995
5110578	Continuous production of potassium nitrate via ion exchange Potassium nitrate is produced by contacting nitric acid with a potassium loaded strong cationic exchange resin. In a preferred embodiment, a solution of potassium nitrate and dilute nitric acid is produced in a continuous liquid solid contacting apparatus...	05/05/1992
5006325	Process for the recovery of nitric acid This invention relates to an improved process for the recovery and regeneration of nitric acid from spent acid obtained from the mixed acid nitration of aromatic compounds. In that process a mixed acid of sulfuric acid and nitric acid is contacted with an...	04/09/1991
4937054	Method of regenerating ZrF₄ pickling solutions A process is disclosed for the regeneration of pickling solutions which contain ZrF4 by addition of a Na compound in which a charge of the pickling solution to be regenerated is analyzed and heated. The amount of Na required for the regeneratio...	06/26/1990
4925639	Removal of nitric oxide from waste gases and recovery as nitric acid A process is provided for removing nitric oxide from effluent vent or flue gas by subjecting the gas cyclically to scrubbing with a nitric acid stream and to electrolysis of the resulting nitric acid stream containing dissolved nitric oxide to oxidize the...	05/15/1990
4783326	Process for the removal of pollutants from hot gases A process for the removal of pollutants from hot flue gas is disclosed. The gas is cooled and at specified temperatures various acids are condensed out. After a further cooling, heavy metals are removed. Precise control of the quantity of water in the flu...	11/08/1988
4572824	Process for recovery of zirconium and acid from spent etching solutions In the manufacture of nuclear fuel tubes spent etching solutions containing nitric acid, zirconium, and hydrofluoric acid are produced as waste. A serial treatment process is employed to recover the zirconium and to restore the solution to the desired aci...	02/25/1986
4339309	Method for removing fluoride contamination from nitric acid Fluoride ions are removed from nitric acid solution by contacting the vaporized solution with alumina or zirconium....	07/13/1982
4138470	Method of preventing escape of nitrogen oxides from an aqueous nitrate solution Nitric oxide may be removed from gases which it is admixed by contacting the gases with aqueous solutions containing nitrate ions in sufficient concentration to oxidize the nitric oxide to nitrous acid and to retain it in the solution under stable conditi...	02/06/1979

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Class 423/394.2 - Purification or recovery