摘要:
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.
摘要:
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. The process comprises the steps of: (a) adding acid selected from the group consisting of sulfuric acid, arsenic acid, perchloric acid, and mixtures thereof to the aqueous mixture in an amount sufficient to catalyze the hydrolysis of the hexafluoroarsenic acid or salt thereof and raising the temperature of the aqueous mixture before, during, or after the acid addition sufficient to remove substantially all of the hydrogen fluoride in subsequent step (b); (b) passing an inert gas through the heated acid mixture steam in a quantity sufficient to remove substantially all of the hydrogen fluoride in the heated acid mixture from the heated acid mixture; and (c) separating substantially all of the hydrogen fluoride from the heated acid mixture whereupon the hexafluoroarsenic acid or salt thereof converts substantially to arsenic acid or salt thereof.
摘要:
An austenitic stainless corrosion resistant alloy and articles made therefrom having good resistance to pitting and crevice corrosion in oxidizing chloride-bearing media combined with resistance to general corrosion and to intergranular corrosion in oxidizing media, containing in weight percent about______________________________________ w/o______________________________________C 0.06 Max.Mn 1.4 Max.Si 0.9 Max.P 0.035 Max.S 0.035 Max.Cr 20-26Ni 34-44Mo 3-
摘要:
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.