A) calcination
B) roasting
C) smelting
D) none of these
Correct Answer: B
Solution :
Roasting is the process of heating the ore in excess supply of air below its melting point. This process is employed when oxidation of ore is required. During roasting moisture is driven away ?volatile impurities are removed ?impurities like sulphur, phosphorus, arsenic are removed as oxides ?the ore undergoes oxidation to form metal oxide or sulphate \[2PbS+3{{O}_{2}}\xrightarrow{{}}2PbO+S{{O}_{2}}\uparrow \] Calcination is the process of heating the ore in limited supply of air below its melting point. The process involves: ?removal of volatile impurities ?removal of moisture ?decomposition of carbonate ore into oxide ore \[F{{e}_{2}}{{O}_{3}}.2{{H}_{2}}O\xrightarrow{\Delta }Fe{{ & }_{2}}{{O}_{3}}+2{{H}_{2}}O(g)\] \[ZnC{{O}_{3}}\xrightarrow{\Delta }ZnO+C{{O}_{2}}\uparrow \] \[CaC{{O}_{3}}.MgC{{O}_{3}}\xrightarrow{{}}CaO+MgO+2C{{O}_{2}}\uparrow \] \[CuC{{O}_{3}}.Cu(O{{H}_{2}})\xrightarrow{{}}2CuO+{{H}_{2}}O+C{{O}_{2}}\uparrow \] Smelting is the process in which the roasted or calcined ore is heated with suitable quantity of coke or charcoal at high temperature above its melting point. \[F{{e}_{2}}{{O}_{3}}+3C\xrightarrow{823\,K}2{{F}_{e}}+CO\] \[ZnO+C\xrightarrow{1600\,K}Zn+CO\]
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