Description
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Niobium is a transition metal that has a grey metallic color in its natural solid state. This element is very rare and oxidizes quickly in air. Niobium has an atomic weight of 92.90638, a melting point of 4491 °F, and a boiling point of 8571 °F. Some common uses of niobium include: as a component in certain types of steel alloys, in welding and nuclear industries, as a component in super alloys, and as a component in electronics and jewelry.
Isolation
Niobium is never found alone in nature, and isolation processes are needed to extract niobium from minerals that it occurs in.
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Some of the more common niobium containing minerals includes columbite, coltan, pyrochlore, and euxenite. The isolation procedures of niobium are especially complicated as niobium occurs in most minerals which contain niobium also contain tantalum. These two elements have extremely similar chemical characteristics, and separating the two is difficult.
Niobium extraction begins with extracting the niobium from ores by fusing the ores with an alkali. The alkali/ore mixture is then treated with hydrofluoric acid. Once the treatment with the acid takes place, tantalum is separated from the acid solution through a liquid-liquid extraction process. During these processes, the tantalum salts that are formed are extracted into MIBK, a ketone. The niobium is left in the hydrofluoric solution. This acidic solution is subject to further extractions of MIBK to remove all of the tantalum that is in the mixture. Niobium is left in an organic solution. Niobium is then converted to its oxide form and reduced to its pure metal form using sodium or carbon.