The present invention provides a method and apparatus for producing
manganese from a
manganese ore without using any carbon or a carbon-containing reductant. The
manganese ore may be a primary ore comprising
rhodochrosite and / or a secondary ore in which manganese is present as at least one of the mineral and mineraloid forms of
manganese oxide and manganese oxyhydroxide, for example. The method (500a) comprises comminuting (501) the manganese ore into fines and converting a manganiferous mineral in the ore into a trivalent
manganese oxide using at least one of a reductant-free pyrometallurgical technique (502) and an inorganic hydrometallurgical technique (503). The trivalent
manganese oxide is then added (505) to an amount of liquid
sodium in excess of the stoichiometric amount thereof required for a
redox reaction between the liquid
sodium and the trivalent manganese
oxide, to produce a
solid phase comprising both elemental manganese and other insoluble products at least comprising
sodium oxide. This
redox reaction is conducted in an
inert atmosphere and its temperature is controlled to remain below about 600 °Celsius to inhibit the production of ternary oxides like α- NaMnO2. The method then comprises separating (506) at least some of the
solid phase from the liquid sodium, and separating (507) the elemental manganese from the other insoluble products, which may be done, for example, based on their different densities. The phase separation (506) and the separation (507) of the elemental manganese from the other insoluble products may be carried out in any order. Thus manganese can be extracted from its ores without producing any
greenhouse gases, and
sodium oxide, or
sodium hydroxide derived from hydrating this
sodium oxide, can be produced as a co-product. If this
sodium oxide and / or
hydroxide, which has a high affinity for
carbon dioxide, is then used to mineralize captured
carbon dioxide, the invention can have a negative
carbon footprint overall. The corresponding apparatus comprises a
comminution device (such as a rock
crusher or grinder), a subassembly for converting the manganiferous mineral in the ore into a trivalent manganese
oxide, a gas-tight reaction vessel for reacting the trivalent manganese oxide with the liquid sodium, a
solid-liquid sodium phase separator for removing excess liquid sodium, and a solid-species separator for separating the elemental manganese from the other insoluble products.