The signifificance of leaching in the extraction of aluminume is

Options

A. to prepate pure alumina from the bauxite ore
B. to refine aluminum
C. to extract aluminium
D. to readuce `Al_(2)O_(3)`

Answer

a

Explanation

Al is abtaned from the ore bauxite which they may be `AlO-OH(Al_(2)O_(3) or Al(OH)_(1)(Al_(2)O_(3) 3H_(2)O)` The first stap is to purily the ore in the Bayer process water materials (maintly into and silicon compounds) , waste removed because these would spoil the properties of the procduce of the produced `NaOH` is added to the ore, and as Al in amplhoteries it dissolves ions forming sodium aluminatarate perticaly iros dissilves as silolves ion .Any insolves water material oparticles ions oxide , are removed by filtering
Next aluminum by hydroxide is preciplateated from the stroughly alkalliting alumitate solution , This may be done other by bubbing in some `CO_(2)` (an oxide which lower the `pH)` or by seeding the solution with `Al_(2)O_(3)` The slicate ions remain in solution .The `All(OH)_(3)` precitated is calclose band stroght) which convers it to perified `Al_(2)O_(3)` serpack process is used when haxide contains relevely at brigh amount of slics as no iroparity. Here bateries is beated with carbon `(at 180^(@)C)` in a currentt of `N_(2)` gas when aluminum obride in formed
`Al_(2)O_(3)C +N_(2) rarr 2AIN + 3CO`
which is sabseparidly decopassed by water
`AIN + 3H_(2)O rarr AI(CH)_(3) + NH_(2)`
fiormation of intmoples as an vabable by products in a distance advamage of the process in hall's process bauxite is beated to bright reducess with `Na_(2)O_(3)` when aluminum (being amphoteric ) disolves to from sodium matalamitale which is then extracted with water
`AI_(2)O_(3) 2H_(3)O + Na_(2)CO_(3) rarr 2NaAIO_(2) + 2H_(2)O + CO_(2)`
Cation dioxide is passed through the solution when altanimum hydroxide is prociplated
`2AI(OH)_(3) overset (Delta) To AI_(2)O_(3) + NaCO_(3)`