Class 423/264 - CHANGING COLOR CHARACTERISTIC OF IMPURITY

Subclass of Class 423 - Chemistry of inorganic compounds
Definition: Processes in which a compound whose color is, or would be,
No. of patents: 25
Last issue date: 01/29/2008

Number	Title	Issue Date
7323156	High pressure/high temperature production of colorless and fancy-colored diamonds The present invention is directed to a method for changing the color of colored natural diamonds. The method includes placing a discolored natural diamond in a pressure-transmitting medium which is consolidated into a pill. Next, the pill is placed into a high press...	01/29/2008
7241434	High pressure and high temperature production of diamonds The present invention is directed to a method for treating discolored natural diamond, especially Type IIa diamond and Type IaA/B diamond with nitrogen as predominantly B centers, for improving its color. The method includes preblocking and preshaping a discolored n...	07/10/2007
7067094	Process for the brightening of sodium hydrogensulfate The process for the brightening of continuously produced sodium hydrogensulfate obtained in the reaction of sodium chloride and concentrated sulfuric acid in molten sodium hydrogensulfate in a circulation reactor, wherein evolved hydrogen chloride and heating gases ...	06/27/2006
6692714	High pressure/high temperature production of colorless and fancy-colored diamonds The present invention is directed to a method for changing the color of colored natural diamonds. The method includes placing a discolored natural diamond in a pressure-transmitting medium which is consolidated into a pill. Next, the pill is placed into a...	02/17/2004
5908802	Nonaqueous solution synthesis process for preparing oxide powders of lead zirconate titanate and related materials A process for producing powders of perovskite-type compounds which comprises mixing a metal alkoxide solution with a lead acetate solution to form a homogeneous, clear metal solution, adding an oxalic acid/n-propanol solution to this metal solution to for...	06/01/1999
5833940	Production of soluble silicates from biogenetic silica Disclosed is a commercial grade of soluble silicate solutions, clear homogenous and water white essentially free of unreacted silica, made by dissolving in a closed container biogenetic silica, preferably rice hull ash, in a strong alkali solution, prefer...	11/10/1998
5801300	Method for determining glycol and formaldehyde contaminants in ground water samples A method for the qualitative determination of the visible levels of glycol and/or formaldehyde at significant concentrations greater than 10 ppm (10 ppm-10,000 ppm range) in a water sample, in which the sample is treated first with periodic acid, then wit...	09/01/1998
5685899	Process for conditioning kaolin clays prior to removing impurities Kaolin clays are conditioned for the removal of colored titaniferous impurities by (A) first mixing the kaolin clay with a collector to condition the impurities, in the absence of a dispersant, but in the presence of sufficient water to yield a mixture ha...	11/11/1997
5567406	Manufacturing clear potassium sulfite Disclosed is a method of manufacturing potassium sulfite from a potassium hydroxide feedstock. A feedstock is tested for the presence of iron and, if the feedstock contains less than 0.3 ppm of iron, it is reacted with sulfur dioxide in an aqueous solutio...	10/22/1996
5169610	Method for the purification of rare earth oxysulfide An efficient method is proposed for decolorizing a rare earth oxysulfide, which is usually slightly colored in grey as prepared by the sulfiding reaction of a rare earth oxide with hydrogen sulfide, by removing sulfur impurity. The method comprises two st...	12/08/1992
5106605	Color restored radiation discolored salt compositons and methods for color restoration Salt compositions which have been discolored during sterilization by means of radioactive radiation such as gamma and/or beta irradiation of the type which causes such discoloration are substantially restored to the original color by treatments disclosed ...	04/21/1992
4572825	Process for bleaching natural chalk For bleaching natural chalk, an aqueous suspension consisting of 50 to 80% by weight fine-grained natural chalk and 50 to 20% by weight water and containing 0.1 to 1.5% by weight, based on the dry weight of the chalk, of a dispersant and optionally contai...	02/25/1986
4529707	Detection of boron impurities in chlorosilanes A method for preparing a chlorosilane sample to enable colorimetric detection of the presence of minute amounts of boron impurities is provided. Detection of boron impurities below five parts per billion is contemplated....	07/16/1985
4451440	Utilization of ion exchange resin in the processing of kaolins A method of processing naturally occurring kaolin clay wherein ion exchange resins are utilized to remove charged soluble impurities from the clay thereby eliminating the filtration step required in conventional clay beneficiation process. Further, by sat...	05/29/1984
4344925	Ozone whitening of synthetic gypsum A process for the whitening of phosphogypsum comprising treating a phosphogypsum in aqueous suspension with an amount of ozone equal to at least 150 parts by weight per million parts by weight of phosphogypsum calculated as Ca SO4.2H.sub.2 O, t...	08/17/1982
4324774	Method for the manufacture of defluorinated phosphatic products The present invention relates to a method for the manufacture of phosphatic products having a very low fluorine content from wet process phosphoric acid. According to the invention the fluorine in the wet process phosphoric acid is removed in the form of ...	04/13/1982
4299807	Methods of producing kaolin pigments A method for producing kaolin pigments of improved coated brightness and opacity is provided in which kaolin is degritted, heated to the level of substantially minimum brightness and then leached. The kaolin may be comminuted before treatment, after heati...	11/10/1981
4271130	Process for the preparation of zeolite A from kaolin The invention provides a process for the production of zeolite A from kaolin by conversion of the kaolin into meta-kaolin followed by reaction of the meta-kaolin in an aqueous alkaline medium, wherein the conversion of the kaolin into the meta-kaolin is c...	06/02/1981
4239736	Method for increasing the brightness of limestone Method for improving the brightness of limestone utilizing a flocculating agent and a bleaching agent where the pH of the slurry is between about 7 and 9....	12/16/1980
4186027	Processing of kaolinitic clays at high solids A process for treating a clay mineral of the kandite group comprising forming a fluid aqueous suspension of the clay mineral, the suspension having a solids content in the range of from 60% to 75% by weight and a pH in the range of from 7.0 to 11.0 and th...	01/29/1980
4150999	Method for manufacture of ferrosilicon nitride Method for the manufacture of ferrosilicon nitride is disclosed. The method produces ferrosilicon nitride with a silicon nitride content of 65% to 85% by weight by oxidizing the metallic iron which is present in the ferrosilicon nitride in an aqueous medi...	04/24/1979
4117085	Treatment of alumina to reduce discoloration A method of reducing discoloration of alumina which is caused by exposure of said alumina to high temperatures is disclosed. The method comprises adding an effective amount of an inorganic oxidizing agent (e.g. H2 O2 or NaOCl) to the...	09/26/1978
4024013	Method of producing citrine crystals A method of producing citrine crystals comprising the step of growing citrine crystals under hydrothermal conditions by the temperature difference method in a high-pressure autoclave on crystalline quartz seeding plates oriented in parallel with the pinac...	05/17/1977
4021294	Process for producing amethyst crystals A process for producing amethyst crystals involving growing of colorless quartz crystals by a hydrothermal method of a temperature drop in a high-pressure autoclave on crystalline quartz seed plates oriented parallel to the crystallographic planes of the ...	05/03/1977
3963585	Distillation of titanium tetrachloride in solution with selected amines In the purification of impure titanium tetrachloride comprising adding an agent to said titanium tetrachloride and thereafter distilling off purified titanium tetrachloride while leaving the impurity in the distillation residue, the improvement which comp...	06/15/1976

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Class 423/264 - CHANGING COLOR CHARACTERISTIC OF IMPURITY