Abstract: The present invention provides a process for recovering arsenic acid from a starting mixture comprising sulfuric and arsenic acids and water. In step (a), the starting mixture is treated with a sulfur (IV) compound which will reduce the arsenic acid to arsenic (III) compound under conditions sufficient to substantially convert the arsenic acid to arsenic (III) wherein the resulting mixture comprises arsenic (III) compound, the sulfur (IV) compound, sulfuric acid, and water. In step (b), the resulting mixture is purged with gas to substantially remove the sulfur (IV) compound from the mixture wherein the purged mixture comprises the arsenic (III) compounds, sulfuric acid, and water. In step (c), the purged mixture is treated under conditions sufficient to substantially separate the arsenic (III) compounds from the purged mixture.

Abstract: The present invention provides a process for the conversion of hazardous hexafluoroarsenic acid or any salt thereof to arsenic acid or salt thereof which can be rendered nonhazardous. In particular, the hexafluoroarsenic acid or salt is converted to arsenic acid or salt which can be converted to a water insoluble salt. Known insolubilization and stabilization technology then renders the material nonhazardous.The present process involves converting hexafluoroarsenic acid or salt thereof contained in an aqueous mixture to arsenic acid or salt thereof.

Abstract: A process for manufacturing high purity anhydrous hydrogen fluoride (HF) having low levels of arsenic impurity by contacting anhydrous hydrogen fluoride product, or an intermediate product obtained during the manufacture of HF, with hydrogen peroxide to oxidize the arsenic impurity in the presence of a catalyst which comprises a catalytic amount of a component selected from the group consisting of molybdenum, a molybdenum compound, vanadium, and a vanadium compound, and a phosphate compound. The volatile trivalent arsenic impurity in the anhydrous hydrogen fluoride is oxidized to a non-volatile pentavalent arsenic compound and the resultant mixture is distilled to recover high purity anhydrous hydrogen fluoride with reduced levels of arsenic impurity. In one embodiment, an oxidizing agent such as nitric acid or a nitrate salt is added to the reaction mixture to oxidize organic compounds.

Abstract: A method for producing alkali metal chromates by a single roast of chrome ores without the use of calcium oxide is disclosed. A double roast embodiment is also contemplated for obtainment of enhanced yields. The pollution and hygiene problems associated with the use of lime are substantially eliminated and only negligible amounts of alumina are found in the product chromate liquors without employing steps previously thought necessary. These advantages are achieved by controlling (1) the Bichromate Equivalent: aluminum oxide ratio in the mix, (2) the amount of alkali metal salts added to the mix, (3) the roasting time, (4) the composition and alkalinity of the liquor used for leaching the roast, and (5) the temperature employed. Recovery of vanadium values from the alkali metal chromate liquors is also disclosed.

Abstract: A method for producing alkali metal chromates by double roasting chrome ores without the use of alkaline earths is disclosed. The pollution and hygiene problems associated with the use of lime are substantially eliminated and only negligible amounts of alumina are found in the product chromate liquors without employing steps previously thought necessary. These advantages are achieved by controlling (1) the Bichromate Equivalent: aluminum oxide ratio in the mix, (2) the amount of alkali metal salts added to the mix, (3) the roasting time, (4) the composition and alkalinity of the liquor used for leaching the roast, and (5) the temperature employed, in both roasts.