Which of the following steps is not involved in metallurgy of iron ?

Options

A. Calcination
B. Smelting
C. Concentration of ore
D. Conversion of ore into oxide

Explanation

To determine which step is not involved in the metallurgy of iron, let's analyze each option provided in the question:

1. **Calcination**: This process involves heating the metal ore in a limited supply of air to remove organic substances. It is a step that can be involved in the metallurgy of iron, especially if the ore contains carbonates or other impurities that need to be removed.

2. **Smelting**: This is the process of heating and melting the metallic ore to extract the metal. Smelting is a crucial step in the metallurgy of iron, as it is used to separate iron from its ore.

3. **Concentration of ore**: This step involves removing unwanted materials or impurities from the ore. Concentration is an essential step in the metallurgy of iron to ensure that the ore is as pure as possible before further processing.

4. **Conversion of ore into oxide**: This step is relevant when the ore is not already in an oxide form. However, iron ores such as magnetite (Fe3O4) and hematite (Fe2O3) are already in oxide form. Therefore, there is no need to convert them into oxides.

Based on the analysis above, the step that is not involved in the metallurgy of iron is:

**Answer: Conversion of ore into oxide (Option 4)**