Abstract: A process in which manganese is recovered from manganese nodules after the nodules have been treated to recover base metals such as copper, nickel, cobalt, and molybdenum. The process includes the steps of reacting the manganese in the nodules to yield a carbonate and subjecting the manganese carbonate to flotation. The manganese carbonate froth is collected from the top of a flotation cell, is dried to produce a manganese concentrate, and is sintered to produce a synthetic manganese oxide. Sintering of such concentrates at 1000.degree. C. yields a product containing greater than 50% manganese.The effect of reagent dosage, pH control, and temperature control on the yield of the synthetic manganese oxide is also disclosed.

Abstract: A system of multiple extraction in which each of the metal elements extracted is bonded to the extractant with a different degree of intensity. To reduce impurities in each metal recovery stage, a bleed stream from each recovery stage is cascaded backwards. In general, the backward cascade disposes of the bleed stream from the most tightly bonded species by recycling it to any preceeding stage of a less tightly bonded species.An example of a process for recovering copper and nickel from an aqueous leach solution containing these values is given. In this type of process, ammonia, copper and nickel are first coextracted onto an organic extractant (oxime). Ammonia is stripped first. In a nickel recovery circuit, nickel values are selectively stripped from the oxime with acid, pure nickel is electrowon, and the acidic, nickel-barren raffinate from the electrowinning cell is recirculated.