Question

Heating of ore in the absence of air below its melting point is called

• A. Leaching
• B. Roasting
• C. Smelting
• D. Calcination

Answer 1

Answer: (D)

Calcination

Answer 2

Calcination is the process in which concentrated ore is heated to a high temp (just below its fusion temp) in the absence of air. Hydrated ores convert into oxides- $Al _{2} O _{3} \cdot 2 H _{2} O {->[\Delta]} Al _{2} O _{3}+2 H _{2} O$ $F e _{2} O _{3} \cdot 3 H _{2} O {->[\Delta]}F e _{2} O _{3}+3 H _{2} O$ Roasting is the process in which air is passed while heating the concentrated ore below its melting point. Smelting is a metallurgical process in which less electropositive metal ore such as $PbO$, $Cr _{2} O _{3}$ are reduced to free metal using the powerful reducing agent like $Al , C , CO$ etc. Metals like $Cu$ and Tin are separated from their respective oxides by poling process using green bamboo stick.