Match the ores given in column-I with type(s) of processes given in column-II.
Column–I | Column–II | ||
(a) | Haematite | (p) | Slag formation during roasting/smelting and bessemerisation. |
(b) | Copper pyrites | (q) | Reduction by carbon monoxide/carbon at different temperatures. |
(c) | Carnallite | (r) | Electrolytic reduction. |
(d) | Bauxite | (s) | Calcination. |
Text Solution
Verified by ExpertsA
(A → p, q, s) ; (B → p) ; (C → r, s) ; (D → r, s)
Sol. Haematite is Fe 2 O 3 . To remove the impurity of FeCO 3 , the ore is heated in absence of air (calcination).
At 500 – 800 K (lower temperature range in the blast furnace)
3 Fe 2 O 3 + CO ⎯→ 2 Fe 3 O 4 + CO 2 ; Fe 3 O 4 + CO ⎯→ 3Fe + 4 CO 2 ; Fe 2 O 3 + CO ⎯→ 2FeO + CO 2
At 900 – 1500 K (higher temperature range in the blast furnance):
C + CO 2 ⎯→ 2 CO; FeO + CO ⎯→ Fe + CO 2
Copper pyrites is CuFeS 2 . During smelting /roasting (now a day) and bessemerisation the impurity of iron sulphide is removed as fusible slag, FeSiO 3 .
2CuFeS 2 + 4O 2 
Cu 2 S + 2FeO + SO 2
2FeS + 3O 2 ⎯→ 2FeO + 2SO 2 ; FeO + SiO 2 ⎯→ FeSiO 3 (slag)
Carnallite (KCl.MgCl 2 .MgCl 2 .6H 2 O) 
MgCl 2 + 6H 2 O
Mg extraction is done by electrolytic reduction of molten mixture of anhydrous MgCl 2 + NaCl + CaCl 2 .
Bauxite is Al 2 O 3 ;
2Al(OH) 3 
Al 2 O 3 + 3H 2 O; Extraction of Al from purified Al 2 O 3 is done by electrolytic reduction of molten alumina dissolved in cryolite or fluorspar.
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