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.