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7166264 |
Processes for purifying phosphoric acid and for preparing phosphoric acid
A process for purifying phosphoric acid includes removing volatile components from phosphoric acid rich in impurities to form a crude phosphoric acid liquid substantially free of volatile...
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7083768 |
Processes for purifying phosphoric acid and for preparing phosphoric acid
A process for purifying phosphoric acid includes removing volatile components from phosphoric acid rich in impurities to form a crude phosphoric acid liquid substantially free of volatile...
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7022242 |
Reduction of wastewater in phosphate manufacturing
Use and reduction of wastewater or “pond water” created by the wet-process phosphoric acid manufacturing there is created a large amount of wastewater or “pond water” to substantially...
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6911191 |
One-step oxidation of wet-process phosphoric acid
A one-step method for production of green-colored, stabilized wet-process phosphoric acid in which black-colored, wet-process phosphoric acid containing incidental metallic impurities and a...
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6861039 |
Method for purification of phosphoric acid high purity polyphosphoric acid
The present invention provides a purification method of phosphoric acid, which includes bringing phosphoric acid containing arsenic into contact with hydrogen halide, thereby to remove the arsenic...
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6758977 |
Purification of phosphoric acid plant pond water
A process for the partial purification of contaminated phosphoric acid plant pond water is described, in which the pond water is treated sequentially, with two basic compounds, clarified, aged,...
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6758976 |
Simplified purification of phosphoric acid plant pond water
A simplified process for the partial purification of contaminated phosphoric acid plant pond water having a molar calcium plus magnesium to fluorine ratio greater than or equal to about 0.60, is...
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6666973 |
Method for fixing fluorine and phosphorus in waste water containing fluorophosphoric acid-derived compound to remove them
A method is provided for fixing and eliminating fluorine and phosphorus in waste water wherein the waste water includes a fluorophosphate compound in which hydrochloric acid is added to the waste...
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6620395 |
Treatment of phospho gypsum
A process is provided for recovering phosphoric acid from phospho gypsum produced as a by-product in a phosphoric acid production process and having water soluble P 2 O 5 bound in the crystal...
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5989508 |
Liquid medium extraction purification method
Method of purification by extraction of at least one substance to be isolated from a liquid medium, comprising an addition to the latter of an organic compound, entrainable by a vapor, which has a...
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5945000 |
Methods of purifying phosphoric acid
In one aspect, the invention includes a method of purifying phosphoric acid comprising filtering a feed solution of phosphoric acid through a membrane, wherein the feed solution is maintained at a...
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5910257 |
Process for producing a semiconductor device using purified phosphoric acid
A process for the preparation of an analytical sample characterized by depositing and separating solely the impurity to be analyzed from phosphoric acid; a process for analysis of the impurity...
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5824132 |
Method of phosphoric acid concentration
The wet process phosphoric acid evaporation, its clarifying, fertilizer production and fertilizer efficiency is improved in the presence of multi-component mixture of anionic surfactants and...
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5449819 |
Process for removing waste pox, alendronate and its by products
Disclosed is a process for removing by-product phosphorus-containing (PO x ) materials, alendronate and alendronate byproducts from crude mother liquors in an omega amino-1-hydroxy-C 2 -C 6 ...
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5431895 |
Process for the removal of lead and cadmium from phosphoric acid
To remove lead and cadmium from phosphoric acid, alkali solution and aqueous sulfide solution are simultaneously introduced with thorough mixing into a phosphoric acid having a P 2 O 5 content of...
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5318707 |
Method of clarifying phosphoric acid
A method for clarifying phosphoric acid by flocculation or coagulation of solids wherein an effective amount of a carboxylic-type polymer having a portion of sulfonic functionality is used as the...
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5312610 |
Defluorination of phosphoric acid
Fluorine in the form of fluoride is removed from phosphoric acid having an initial phosphate concentration of less than about 50 percent by determining the concentration of fluoride to be removed...
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5279806 |
Process for eliminating heavy metals from phosphoric acid
Process for treating phosphoric acid for removing heavy metal cations, in particular cadmium, and sludges contained in the acid, characterized in that concentrated phosphoric acid having a low...
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5246681 |
Process for the removal of cadmium from solutions of phosphoric acid
Process for the removal of cadmium from solutions of phosphoric acid derived by the sulphuric and nitric digestion of phosphatic rocks, including the following steps: adding to the phosphoric...
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5236679 |
Removal of aluminum contamination during production of phosphoric acid
This invention provides a method for removing aluminum contamination from phosphoric acid during the acidulation of phosphate rock with sulfuric acid in the presence of recycled phosphoric acid....
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5230876 |
Removal of vanadium from phosphoric acid
An apparatus for removing vanadium from phosphoric acid includes a precipitator that receives vanadium-containing process-feed phosphoric acid and adds an oxidant to the process-feed phosphoric...
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5211928 |
Method of improving gypsum slurry filtration in the production of phosphoric acid
A method for improving gypsum slurry filtration in the production of wet process phosphoric acid wherein an effective amount of carboxylic-type polymer having a portion of sulfonic functionality is...
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5185135 |
Method of dewatering a wet process phosphoric acid slurry
A digested slurry from a wet process phosphoric acid production process is dewatered by gravity-assisted vacuum filtration using as a filtration aid an aqueous solution of a polymeric filtraton aid...
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5173280 |
Method of clarifying phosphoric acid using high charge sulfonic-type polymers
A method for clarifying phosphoric acid by flocculation or coagulation of solids wherein an effective amount of a polymer having a predominantly sulfonic functionality is used as the clarification...
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5171548 |
Process for the removal of vanadium from wet process phosphoric acid
A process for removal of vanadium from wet process phosphoric acid comprising the steps of; (i) adsorbing an anionic pentavalent complex of vanadium, derived from the wet process phosphoric...
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5171452 |
Phosphoric acid wastewater treatment
Phosphoric acid wastewater treatment to substantially eliminate discharge of contaminants to the environment. Acid pond water from conventional wet-phosphoric acid manufacturing is replaced by...
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5124137 |
Process for the preparation of alkali metal phosphate solutions
Alkali metal phosphate solutions having a fluorine content of less than 20 ppm, based on P 2 O 5 , are prepared by first digesting crude phosphate using sulfuric acid, and separating the calcium...
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5120519 |
Scale control in phosphoric acid manufacture
High molecular weight copolymers of acrylamide which contain between 5-100 mole % of acrylic acid and have a molecular weight of at least 1,000,000 prevent scale adhering to surfaces in contact...
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5084261 |
Recovery and utilization of gypstack leachate in hemihydrate phosphoric acid process
Disclosed is a process for treating a waste stream containing calcium sulfate by depositing said waste stream on a gypstack, collecting the leachate from the gypstack, and recovering the P 2 O 5 ...
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5066471 |
Lowering post-precipitation in merchant acid
The present process stabilizes merchant acid from bottoms solutions against post-precipitation by heating the acid to a temperature of at least about 180° F. for about 12 to about 48 hours. The...
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5002744 |
Method for defluorinating wet process phosphoric acid
A method for defluorinating wet process phosphoric acid. Phosphatic waste clay from phosphate rock beneficiation is mixed with the wet process phosphoric acid. The mixture is heated for a time...
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4994248 |
P.sub.2 O.sub.5 recovery and phosphoric acid purification
Disclosed is an improved process for purifying phosphoric acid where a calcium sulfate hemihydrate slurry is first filtered to produce a first filtrate and a filter cake which comprises calcium...
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4988489 |
Recovery of phosphorus values from waste phosphoric acid liquors
The phosphorus values from waste phosphoric acid containing organic contaminents such as wastes obtained in the manufacture of quinacridone pigments can be recovered in purified form by hydrolyzing...
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4986970 |
Method for removal of heavy metals, especially cadmium, from phosphoric acid containing solutions
The present invention relates to a method for removal of heavy metals, especially cadmium, from phosphoric acid containing solutions, primarily such solutions made by digestion of rock phosphate by...
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4978511 |
Methods for selectively recovering vanadium from phosphoric acid and vanadium sources
Vanadium is selectively recovered from vanadium-containing phosphoric acid solutions also containing metals other than vanadium by selectively converting the dissolved vanadium to a vanadate...
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4971778 |
Process for working up phosphoric acid
For working up concentrated, preferably partially condensed phosphoric acid which is contaminated with organic components, the phosphoric acid is first thoroughly mixed with fine-grained sand in a...
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4906445 |
Continuous process for complete removal or organic impurities from and complete decolorization of prepurified wet-process phosphoric acid
A continuous process is indicated for complete removal of organic impurities from and complete decolorization of pre-purified wet-process phosphoric acid which has been purified by an extractive...
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4857211 |
Cleaning of filter surfaces
Encrusted filter surfaces that have been used for filtering wet process phosphoric acid slurries are effectively cleaned, e.g., of crystalline deposits, by washing same with a solution of fluosilic...
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4851199 |
Methods for recovering vanadium from phosphoric acid and vanadium sources
Vanadium is recovered from vanadium-containing phosphoric acid solutions by adjusting the pH so as to convert the dissolved vanadium to a simple vanadate compound which is insoluble in the...
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4844873 |
Separation and recovery of solids from liquids containing them using the ionic flotation process
Improvement to the separation and recovery of solids from liqiuds containing them, and using a ionic flotation process, implementing an installation characterized in that it comprises at least a...
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4834960 |
Process for purifying phosphorous acid
The purification of phosphorous acid which is formed in halogenations of hydrocarbon derivatives using phosphorus trihalides is carried out in the context of preparing phosphorous acid in a...
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4824650 |
Method for extracting arsenic and heavy metals from phosphoric acid
An improved, low cost, liquid extraction method for significantly reducing the arsenic and other heavy metal content of phosphoric acid is disclosed which can routinely achieve essential...
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4822582 |
Process for the removal of heavy metals from acid, phosphate-containing, aqueous media
A process for the removal of heavy metals from an acid phosphate containing, liquid medium in which process a precipitate containing heavy metals is formed and is subsequently separated and wherein...
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4820501 |
Method for removing organic materials dissolved in purified phosphoric acid
A method for removing organic materials dissolved in purified phosphoric acid by decomposing it with hydrogen peroxide, characterized in that after the treatment with hydrogen peroxide, the...
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4816241 |
Gaseous reduction of phosphoric acid
A process for reducing the valence state of ferrous and other ions present in phosphoric acid by heating the acid in the presence of a pressurized reducing gas, preferably hydrogen. The pressurized...
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4808391 |
Oxidation-reduction process for enhancing the color of and stabilizing wet process phosphoric acid
A two-stage oxidation/reduction process for preparing commercially valuable, color enhanced and stabilized low viscosity wet process phosphoric acid is provided which yields improved acid that can...
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4806324 |
Process for making phosphoric acid free from titanium
Phosphoric acid substantially free from titanium is made from the organic extract obtained by subjecting crude phosphoric acid containing titanium to extractive purification with an organic solvent...
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4806323 |
Method for the removal of cadmium from acid phosphate-containing aqueous media
Cadmium is removed from an acid, phosphate-containing aqueous medium with the aid of an anion exchanger, in which process, during the removal, iodide or bromide ions are present in a quantity of...
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4804526 |
Process for purifying phosphoric acid for electrical semiconductor use
Phosphoric acid is treated to remove and/or tie up heavy metals and antimony to enable the acid to be used in electrical semiconductor applications by reacting the acid with hydrogen sulfide and...
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4800071 |
Filtration aids for removal of calcium solids from aqueous phosphoric acid
Separation of gypsum from phosphoric acid liquor produced during the production of phosphoric acid from finely ground phosphate rock. These aids are characterized as containing sulfonate and...
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