Big Chemical Encyclopedia

Chemical substances, components, reactions, process design ...

Articles Figures Tables About

Reaction with aluminium ores

Manganese is the third most abundant transition metal, and is widely distributed in the earth s crust. The most important ore is pyrolusite, manganese(IV) oxide. Reduction of this ore by heating with aluminium gives an explosive reaction, and the oxide Mn304 must be used to obtain the metal. The latter is purified by distillation in vacuo just above its melting point (1517 K) the pure metal can also he obtained by electrolysis of aqueous manganese(II) sulphate. [Pg.384]

Bacteria associated with bauxite ore have been shown to reductively mobilize significant amounts of the Fe(III) oxides in the bauxite under anaerobic conditions without mobilizing significant amounts of the Al(III) oxides like gibbsite or boehmite as long as the pH of the reaction system was kept above 4.5. The bauxite residue was thus enriched in aluminium (Ehrlich et al., 1995 Ehrlich Wickert, 1997). [Pg.22]

An alternative fluoride breakdown process for beryl was used during the 1939-45 war by the Sappi Company in Italy. This was based upon the reaction with sodium hydrogen fluoride (NaF.HF) at a temperature of about 680°C. The fluoride reagent is mixed with the ground ore and made into briquettes with a little water, ready for firing in the breakdown furnace. The reaction converts the beryllium to a complex fluoride, believed to be 3NaF.2Bep2, without fluorination of the aluminium and silicon components. [Pg.64]

It is true to say that almost all the reactions by which a metal is extracted from its ore are reduction reactions. Discuss this statement with respect to the extraction of iron, aluminium and zinc. [Pg.172]

The ore is first treated with caustic soda under pressure. The aluminium largely dissolves as the aluminate, the iron oxide is insoluble and the silica also remains in the form of a sodium aluminium silicate, which leads to a loss of aluminium. Hence the best bauxites are those low in silica. After filtration, the hydrated aluminium oxide is reprecipitated by seeding and the caustic soda solution may be re-used. The alumina is washed and then heated at 1200°C to remove water. The final step in the production of aluminium metal has to be electrolytic since the reduction of alumina with carbon is only possible at very high temperatures and the reverse reaction occurs on cooling. Moreover, because of the chemistry of aluminium, the electrolysis medium cannot be water in fact almost all commercial production of aluminium during the last ninety years has used an electrolysis in molten cryolite (Na3AlF5). [Pg.115]


See other pages where Reaction with aluminium ores is mentioned: [Pg.717]    [Pg.717]    [Pg.134]    [Pg.210]    [Pg.234]    [Pg.137]    [Pg.134]    [Pg.52]   
See also in sourсe #XX -- [ Pg.368 ]




SEARCH



Aluminium ores

Aluminium reaction with

Aluminium reactions

© 2024 chempedia.info