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Electrolytic manganese is a pure form of the metallic element manganese, Mn. It is termed "electrolytic" because a major step in the refining process involves electrolysis, a chemical reaction driven by an electric current. Less pure forms, such as ferromanganese and silicomanganese, are derived by more economical methods. The pure metal is primarily used as an alloy in the production of stainless steel and aluminum. Electrolytic manganese is also used extensively as an element in lithium-ion batteries designed for electric vehicles.
The initial stages of manganese processing involve heating the ore and using chemical treatments to remove the majority of impurities. Electrolysis is then used to further refine the metal. A solution of the material is placed in an electrolytic cell and a direct electrical current is passed through. The direct current induces a chemical reaction that separates the manganese from naturally occurring contaminants.
Electricity enters the cell through the anode, a negative electrode, and exits through the cathode, a positive electrode. Passing a direct current through the manganese solution can cause either oxidation, a loss of electrons, or reduction, a gain in electrons. This results in electrolytic manganese metal (EMM) collecting on the positive cathode and electrolytic manganese dioxide (EMD) collecting on the negative anode. The electrodes are removed periodically and the manganese deposits collected in the form of flakes. Heating the flakes to 925°F (500°C) removes latent hydrogen and results in a manganese powder with purity in excess of 99.9%.
The great majority of manganese refined each year is used as an alloy in the processing of other metals. Steelmaking accounts for most of the total with the purer electrolytic manganese used in the production of high grade stainless steel. It is also used in making a corrosion resistant aluminum.
Electrolytic manganese dioxide is predominately used in making the cathode, or positive pole, of dry cell batteries. New battery designs and applications rely more heavily on manganese. The lithium-ion batteries that power many electric vehicles typically use EMM in making the cathode and EMD in producing the battery's anode.
Manganese is a common element, but the majority of its deposits are in the form of nodules on the seafloor. Commercially viable deposits on land are not evenly distributed, with China, Australia, and South Africa having significant mining and production capabilities. Countries that rely heavily on imports of the metal sometimes view the concentration of mining and processing in so few hands as a strategic threat to their economy.