Abstract: A method and system of removing or decreasing waste liquor manganese concentration to less than about 1 mg/L total manganese without the precipitation of significant amounts of magnesium. The method and system include steps for treating the waste liquor using three separate circuits in which in the first circuit, manganese is reduced, for example, from about 2 g/L to <500 mg/L using pH adjustment with a suitable neutralizing agent; and in the second circuit, the final target manganese level is achieved by oxidative precipitation using a suitable oxidizing agent. Part of the precipitated manganese product, e.g., MnO2, is recycled to the oxidative precipitation circuit as seed and the balance proceeds to a third circuit wherein the precipitated manganese product is re-dissolved, and then recycled to the first neutralization circuit. In the first neutralization circuit and the second oxidative precipitation circuit, the process conditions are selected to minimize the precipitation of magnesium, e.g., Mg(OH)2.

Abstract: A method and system of removing or decreasing waste liquor manganese concentration to less than about 1 mg/L total manganese without the precipitation of significant amounts of magnesium. The method and system include steps for treating the waste liquor using three separate circuits in which in the first circuit, manganese is reduced, for example, from about 2 g/L to <500 mg/L using pH adjustment with a suitable neutralizing agent; and in the second circuit, the final target manganese level is achieved by oxidative precipitation using a suitable oxidizing agent. Part of the precipitated manganese product, e.g., MnO2, is recycled to the oxidative precipitation circuit as seed and the balance proceeds to a third circuit wherein the precipitated manganese product is re-dissolved, and then recycled to the first neutralization circuit. In the first neutralization circuit and the second oxidative precipitation circuit, the process conditions are selected to minimize the precipitation of magnesium, e.g., Mg(OH)2.

Abstract: A cost-effective broad temperature method for removing troublesome low valent sulfur compounds from aqueous streams. The process utilizes sulfur dioxide, oxygen and at least one metal catalyst (which may be added to or already entrained in the aqueous stream) to oxidize the low valent sulfur compounds.

Abstract: The cyanide content of waste waters containing the same is removed by treatment with sulfur dioxide or an alkali or alkaline earth metal sulfite or bisulfite in the presence of excess oxygen and a metal catalyst which is perferably copper.

Abstract: Cobalt salts are produced by dissolving cobalt metal in hydrochloric acid containing a small amount of thiosulfate ions.

Abstract: This invention is concerned with a process for dissolving oxidic trivalent cobalt compounds in hydrochloric acid while avoiding the generation of chlorine. It includes the following steps (a) slurrying in water the trivalent cobalt compound to be dissolved and (b) treating the resulting slurry with a reduction agent from the group consisting of methanol, formaldehyde and formic acid and with hydrochloric acid. The contact of the hydrochloric acid with the slurry should occur in the presence of the reducing agent. The rate of acid addition should be controlled to maintain the slurry at a pH above 1.