Calcination is used for removing volatile components like water and carbon dioxide from ores by heating in limited air. Roasting, on the other hand, involves heating sulfide ores in the presence of oxygen.
Step 1: Understanding Calcination Calcination is the process of heating an ore in the absence or limited supply of air to remove volatile impurities such as water (\( H_2O \)), carbon dioxide (\( CO_2 \)), or sulfur dioxide (\( SO_2 \)). It is used primarily for carbonate and hydrated ores.
Step 2: Analyzing the Given Reactions 1. Reaction (1): Roasting Process - This reaction involves heating a sulfide ore (\( Cu_2S \)) in the presence of oxygen (\( O_2 \)), leading to the formation of oxide (\( Cu_2O \)) and the release of sulfur dioxide (\( SO_2 \)). - This is a roasting process, not calcination. 2. Reaction (2): Dissolution Reaction - This reaction involves aluminum oxide (\( Al_2O_3 \)) reacting with sodium hydroxide (\( NaOH \)) and water to form sodium aluminate. - This is a leaching reaction, not calcination. 3. Reaction (3): Roasting Process - This reaction involves heating a sulfide ore (\( CuFeS_2 \)) in the presence of oxygen (\( O_2 \)), forming copper sulfide (\( Cu_2S \)), iron sulfide (\( FeS \)), and sulfur dioxide (\( SO_2 \)). - Since it involves oxidation of sulfides, it is also a roasting process, not calcination. 4. Reaction (4): Calcination Process - This reaction involves heating hydrated iron oxide (\( Fe_2O_3 \cdot xH_2O \)) to remove water (\( H_2O \)), leaving behind anhydrous iron oxide (\( Fe_2O_3 \)). - This matches the definition of calcination. Step 3: Evaluating the Given Options - Option (1): Incorrect, as it represents roasting. - Option (2): Incorrect, as it represents a dissolution reaction. - Option (3): Incorrect, as it represents roasting. - Option (4): Correct, as it represents the calcination of hydrated iron oxide. Thus, the correct answer is
