What do you understand by roasting in presence of NaCl?

Explanation

**Step-by-Step Solution:**

1. **Definition of Roasting:**
Roasting is a metallurgical process that involves heating an ore in the presence of oxygen. This process is typically used to convert sulfide ores into oxides or to remove impurities.

2. **Roasting in Presence of NaCl:**
When we refer to roasting in the presence of NaCl (sodium chloride), it specifically means that the ore is heated along with an excess of sodium chloride. This process is carried out in the presence of air (oxygen) at a temperature that is below the melting point of the ore.

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