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The waste solid, bauxite tailings, is removed and aluminium hydroxide is precipitated from the remaining solution of sodium aluminate. This aluminium hydroxide can be converted to aluminium oxide or alumina by calcination. [citation needed] The residue or bauxite tailings, which is mostly iron oxide, is highly caustic due to residual sodium ...
One third of the potential octahedral spaces are missing a central aluminium. The result is a neutral sheet: with aluminium as a +3 ion and hydroxide a −1 ion, the net cationic charge of one aluminium per six hydroxides is (+3)/6 = +1/2, and likewise the net anionic charge of one hydroxide per two aluminium atoms is (−1)/2 = −1/2.
At these temperatures, the aluminium is dissolved as sodium aluminate (primarily [Al(OH) 4] −) in an extraction process. After separation of the residue by filtering, gibbsite is precipitated when the liquid is cooled and then seeded with fine-grained aluminium hydroxide crystals from previous extractions. The precipitation may take several ...
Carl Josef Bayer (also Karl Bayer, 4 March 1847 – 4 October 1904) was a chemist from Austria-Hungary who invented the Bayer process of extracting alumina from bauxite, essential to this day to the economical production of aluminium.
The flux method is a crystal growth method where starting materials are dissolved in a solvent (flux), and are precipitated out to form crystals of a desired compound. The flux lowers the melting point of the desired compound, analogous to a wet chemistry recrystallization. [1]
Well-developed crystals are found in the emery deposits of the Ural Mountains and at Chester, Massachusetts, and in kaolin at Schemnitz in Hungary. If obtainable in large quantity, it would be of economic importance as a source of aluminium. [5] Diaspore, along with gibbsite and boehmite, is a major component of the aluminium ore bauxite. [3]
The Hall–Héroult process is the major industrial process for smelting aluminium.It involves dissolving aluminium oxide (alumina) (obtained most often from bauxite, aluminium's chief ore, through the Bayer process) in molten cryolite and electrolyzing the molten salt bath, typically in a purpose-built cell.
Pseudoboehmite can be synthesized by aging non-crystalline aluminium hydroxide gels at pH values between 5.0 and 7.4. [5] Uses