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| Number | Title | Issue Date |
| 7201885 | Method of removing heavy metals from silicate sources during silicate manufacturing Methods for the removal of lead from a metal silicate during the process of manufacturing of such a material are provided. With the reliance upon lower cost starting silicon dioxide starting materials that are known to exhibit elevated amounts of heavy metal therein... | 04/10/2007 |
| 7172742 | Method of preparing wet process phosphoric acid The present invention relates to a method of preparing wet process phosphoric acid, which comprises: dividing raw materials which contain phosphate rock slurry and sulfuric acid into two parts, and then feeding these two parts into two reactors separately. In the fi... | 02/06/2007 |
| 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 components; heating the crude phosphoric acid liquid to a temperature above 25... | 01/23/2007 |
| 6962618 | Device for separating air from flotation foam Device and process for the removal of air from flotation foam formed during the flotation of a paper-fiber-containing suspension. The device includes a driven rotor that includes a shaft and at least one rotor blade positioned on the shaft, and a non-rotating wall a... | 11/08/2005 |
| 6544489 | Defoaming compositions for high acid strength media A defoaming composition useful in high strength acid media includes an ester condensate of a C12 -C20 fatty acid and a at least one alcohol derivative selected from the group consisting of C1 -C4 alcohol ethoxyl... | 04/08/2003 |
| 6365117 | Method for preparing phosphoric acid A method for preparing phosphoric acid from calcium phosphate ores, particularly ores highly contaminated with organic compounds, by decomposing the ore with sulphuric acid, wherein according to the invention the process of decomposition of calcium phosph... | 04/02/2002 |
| 6251351 | Wet-process technique for refining phosphoric acid A process for purification by multistage countercurrent extraction of wet-process phosphoric acid includes the steps of (a) preparing an aqueous phosphoric acid by decomposition of crude phosphates with sulfuric acid and prepurification thereof; (b) provi... | 06/26/2001 |
| 6235257 | Process waters in phosphate manufacturing Modification of phosphoric acid manufacturing provides improved process waters: decontaminated water pH-adjusted to be only slightly acidic, scrubber process water, gypsum stack water, and a composite of the latter two waters. The composite water undergoe... | 05/22/2001 |
| 5679315 | Method of production of high purity silica The present invention provides a basic method for producing high purity silica and ammonium fluoride from silicon tetrafluoride-containing gas, particularly the gas generated by acidulation. The basic method comprises recovering silicon tetrafluoride-cont... | 10/21/1997 |
| 5395603 | Automatic control system for a chemical process, especially a wet process phosphoric acid plant Maximum throughput of a wet process phosphoric acid plant at a fixed recovery can be obtained by controlling the filter feed to give a desired specific gravity of the filtrate from the last washing of the gypsum cake. The filtrate from the last washing of... | 03/07/1995 |
| 5366640 | Conversion of phosphoric acid waters Converting wet-process phosphoric acid operations, to minimize and nearly eliminate discharge of contaminants to the environment, by generation, use, and treatment of new and unique process waters. Fluorides and other contaminants soluble under acidic con... | 11/22/1994 |
| 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 clarification aid. Preferred polymers are high molecular we... | 06/07/1994 |
| 5316748 | Phosphoric acid manufacturing with converted waters Generation, use, and treatment of new and unique process waters in or for wet-process phosphoric acid manufacturing to substantially eliminate discharge of contaminants to the environment. Acid pond water from conventional wet-process phosphoric acid manu... | 05/31/1994 |
| 5211735 | Process for preparing phosphated or nitrophosphated fertilizers through solubilization of phosphate rock The invention aims at a process for preparing phosphated or nitrophosphated fertilizers through reaction of phosphate rock in aqueous pulp, with sulfuric and/or phosphoric acids, with addition, or not, of ammonia, so as to produce fertilizers of the types... | 05/18/1993 |
| 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 used as the filtration aid. Preferred polymers are high m... | 05/18/1993 |
| 5188812 | Automatic control system for a phosacid attack tank and filter A method for controlling the phosphoric acid product concentration in a continuous phosphoric acid recovery process comprising supplying a constant feed stream of phosphate ore to an attack tank wherein the phosphate ore is subjected to attack by sulfuric... | 02/23/1993 |
| 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 that has been subjected to high shear mixing to enhance t... | 02/09/1993 |
| 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 aid. Preferred polymers are high molecular weight acrylami... | 12/22/1992 |
| 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 with digested phosphate rock and/or phosphoric acid produced ... | 06/09/1992 |
| 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 P2 O5 values therefrom. Also disclosed is appa... | 01/28/1992 |
| 5009873 | Crystal modification in wet process phosphoric acid production A wet process production of phosphoric acid in which phosphate rock is digested, whereby phosphoric acid is released and calcium sulfate crystals are formed, employs a polymeric crystal modifier in the digestion stage of the process to improve the separat... | 04/23/1991 |
| 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 sufficient to remove fluorine from the acid as gaseous silicon... | 03/26/1991 |
| 4994248 | P2 O5 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 sulfate hemihydrate, the calcium sulfate hemihydrate filter c... | 02/19/1991 |
| 4853201 | Recovery of P2 O5 values from phosphoric acid hemihydrate crystals P2 O5 values occluded in the crystals which are precipitated during the hemihydrate process for manufacturing phosphoric acid are recovered by dissolving and recrystallizing the hemihydrate crystals as dihydrate crystals in an acidic... | 08/01/1989 |
| 4834787 | Phosphate rock utilization A process providing solubilization of phosphate rock by contacting the rock with sulfurous acid in the presence of an oxidizing agent selected from the group consisting of hydrogen peroxide and ozone. Use of sulfurous acid in combination with a substoichi... | 05/30/1989 |
| 4828811 | Method for producing phosphoric acid from phosphate ore A process and apparatus for producing phosphoric acid by the recovery of P2 O5 from a phosphate ore is disclosed. A slurry of a phosphate ore in an aqueous phosphoric acid solution is formed in each of a plurality of reaction zones c... | 05/09/1989 |
| 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 at least one of the two additives (a) sulphate ions and (... | 04/18/1989 |
| 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 acrylamide.... | 01/24/1989 |
| 4797265 | Process for the production of highly concentrated phosphoric acid A process for the production of highly concentrated phosphoric acid, comprises improvements in digesting phosphate rock with a mixed acid consisting essentially of sulfuric acid and phosphoric acid to obtain a slurry comprising phosphoric acid and hemihyd... | 01/10/1989 |
| 4780294 | Process for making crude phosphoric acid Crude phosphoric acid is made by subjecting crude phosphate ore containing sulfide to processing treatment with a mineral acid in a closed system comprised of a processing reactor, a filtering zone and an off-gas scrubbing zone. To this end, a soluble com... | 10/25/1988 |
| 4777027 | Continuous process for preparing phosphoric acid and calcium sulphate There is described a process which comprises adjusting on the one hand the flow rates of a circulating mixture relative to a base flow rate according to very specific specifications, and on the other hand so adjusting the reaction conditions in succeeding... | 10/11/1988 |
| 4762698 | Method for increasing fluosilicic acid recovered from wet process phosphoric acid production A method is disclosed for increasing the fluosilicic acid (FSA) recovered from a wet process phosphoric acid manufacturing process. The filtrate obtained by washing a filter cake is pumped to a stripper and reacted with H2 SO4 to con... | 08/09/1988 |
| 4743438 | Process for producing phosphoric acid from low purity phosphate rock An improved process for extending the capabilities of an existing, conventional wet-process phosphoric acid production plant to more effectively utilize phosphate values contained in low purity phosphate rock which process comprises (1) adjustment of the ... | 05/10/1988 |
| 4734272 | Phospho-gypsum recovery process This disclosure involves a process for treating wet phospho-gypsum, a by-product from wet phosphoric acid manufacture, to remove fluorine values so as to make the sulfur values in the phospho-gypsum usable in making sulfuric acid in a contact sulfuric aci... | 03/29/1988 |
| 4714600 | Process for production of phosphoric acid from dry matrix by SO3 treatment and extraction Phosphoric acid is produced from dry phosphate ore, matrix by acidulation with sulfur trioxide in the presence of sulfuric acid catalyst to form polyphosphoric acid, treatment with sufficient water to convert the polyphosphoric acid to orthophosphoric aci... | 12/22/1987 |
| 4684512 | Phosphate recovery from wet phosphoric acid purification process The invention is a process for recovering phosphorus value from magnesium pyrophosphate containing filter media in the wet superphosphoric acid purification process. The invention comprises treating the filter cake with a salt to remove the adhering phosp... | 08/04/1987 |
| 4683127 | Process for making wet-process phosphoric acid Wet-process phosphoric acid is made by subjecting a phosphate ore to processing treatment with a mineral acid resulting in the formation of a processed suspension. The formation of silicofluorides is obviated by adding, either to the phosphate ore or the ... | 07/28/1987 |
| 4643882 | Process for recovery by a solvent of the uranium present in phosphoric acid A process for the recovery of the uranium present in phosphoric acid produced by a wet process in (A) by means of a suitable solvent (L9), which is carried out after separation of the gypsum in (B) formed in the attack operation, and eliminatio... | 02/17/1987 |
| 4637922 | Method for removing organic materials from a wet process phosphoric acid A method for removing organic materials from a wet process phosphoric acid obtained by treating an uncalcined phosphate rock with sulfuric acid. The wet process phosphoric acid is contacted with a reducing material having a standard single electrode poten... | 01/20/1987 |
| 4636372 | Aluminum fluorophosphates made from impure phosphoric acids and conversion thereof to alkalimetal phosphates Alkali metal phosphates and HF can be produced from a substantially calcium-free fluoroaluminum phosphate precipitate (which also contains iron) made by the aging of wet process phosphoric acid containing iron, fluorine and aluminum, preferably phosphoric... | 01/13/1987 |
