Write down the reactions taking place in different Zones in the blast furnance during the extraction of Iron.
How can you separate alumina from silica in a baxuite ore associated with silica? Give equations, if any.
Aluminium bauxite is carried out by digesting the powdered ore with a concentrated solution of NaOH at 473 – 523 K and 35 – 36 bar pressure.
Al2O3(s)+2NaOH(aq) +3H2O(l)→ 2Na[Al(OH)4(aq)
The aluminate in solution is neutralised by passing CO2 gas and hydrated Al2O3 is precipitated:
2Na[Al(OH)4](aq) + CO2(g) → Al2O3.xH2O(s) + 2NaHCO3(aq)
The sodium silicate remains in the solution and hydrated alumina is filtered, dried and heated to give back pure Al2O3.
Name the processes from which chlorine is obtained as a bye-product. What will happen if an aqueous solution of NaCl is subjected to electrolysis?
Outline the principles of refining of metals by the following methods:
(i) Zone refining.
(ii) Electrolytic refining.
(iii) Vapour phase refining.