Patent
Process for producing fluorine compounds and amorphous silica
Subhas K. Sikdar,James H. Moore +1 more
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TLDR
In this article, a mixture of precipitated amorphous silica and dissolved sodium fluoride is separated from the aqueous slurry, leaving a solution of sodium fluoride, which can be used as such or reacted with other substances (such as alumina, to form synthetic cryolite).Abstract:
Hydrofluoric acid and/or other fluorine compounds are recovered by reacting fluosilicic acid with a sodium-containing compound to form an alkaline aqueous slurry comprising precipitated amorphous silica and dissolved sodium fluoride. The precipitated amorphous silica is separated from the alkaline aqueous slurry leaving an aqueous solution of sodium fluoride. The sodium fluoride solution can be used as such or reacted with other substances (such as alumina, to form synthetic cryolite). Sodium fluoride is recovered from the aqueous solution (as by evaporation or extraction) and used per se or reacted with sulfuric acid to produce hydrogen fluoride.read more
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Patent
Method and apparatus for purifying hydrogen fluoride.
John B. Davison,Chung-Tseng Hsu +1 more
TL;DR: A method and apparatus for purifying hydrofluoric acid, comprising the steps of filtering the acid to remove particulates, passing the filtered acid through a cation exchange material and an anion exchange material to remove ions therefrom, periodically monitoring the acid that has passed through the cation-exchange material for a level of cationic impurity representative of actual or impending ionic breakthrough in the ionic exchange material, and periodically monitoring (44, 46, 46) the acid which has passing through the anion-interference, interrupting the flow of acid at
Journal ArticleDOI
Recovery of high surface area mesoporous silica from waste hexafluorosilicic acid (H2SiF6) of fertilizer industry
TL;DR: The process reported in this study may significantly reduce the release of hazardous materials into the environment and it might confer economic benefits to the responsible industries.
Patent
Process for treating red mud to recover metal values therefrom
TL;DR: A method for processing red mud to recover iron, aluminum, silicon and titanium metal values from red mud is described in this article, where the acid is added to a digester containing an acid to provide a mixture of acid and red mud and heating the mixture to dissolve soluble compounds of at least one of iron, aluminium, silicon, and titanium.
Patent
Method of production of high purity silica and ammonium fluoride
TL;DR: In this paper, a method for producing high purity silica and ammonium fluoride from silicon tetrafluoride-containing gas was proposed, where the recovered gas can be converted to an ammonium fluosilicate solution and is ammoniated to produce high purity ammonium and silica.
Patent
Apparatus and method for recovering solvent
TL;DR: In this paper, a solvent recovery system for an oil and grease test collects and condenses solvent vapors to recover solvent, where solvent is filtered through a filter paper placed in a funnel integral with the vessel.
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Patent
Recovery of hydrofluoric acid from fluosilicic acid with high pH hydrolysis
Subhas K. Sikdar,James H. Moore +1 more
TL;DR: In this article, hydrogen fluoride is recovered from the first slurry leaving a first solution which is reacted with sodium fluosilicate or fluosilicic acid or both to form a second slurry comprising silica and dissolved sodium fluoride.
Patent
Process for the production of ammonium fluoride from fluosilicic acid
TL;DR: In this article, the ammonium fluoride filtrate is left standing for at least 30 minutes to permit flocculation of silicon dioxide contained therein and the flocculated silicon dioxide is separated off.
Patent
Process for treating sodium silico fluoride
Hirokazu Satoh,Akira Fujimura +1 more
TL;DR: In this article, a process of the treatment of sodium silico fluoride is described, in which the mixture of sodium fluoride and silica gels are separated from the mixed aqueous slurry solution by means of the filter, washed with water and dried.