Question

Which method is used to concentrate sulphide ores?

• A. Magnetic separation
• B. Hand picking
• C. Froth flotation
• D. Washing

Hint:

Sulphide ores are concentrated by the froth flotation process because sulphide particles preferentially attach to froth.

Answer 1

The Correct Option is C

Concept:
Before extracting metals from ores, impurities such as sand, clay, and rocky materials must be removed. This process is called concentration or ore dressing. Different concentration methods are used depending upon the nature of the ore and impurities. Sulphide ores are generally concentrated using the froth flotation process.

Step 1: Understanding froth flotation process.
In the froth flotation method:
• The powdered sulphide ore is mixed with water to form slurry.
• Pine oil or similar substances are added.
• Air is blown through the mixture. Sulphide ore particles become wet by oil and rise upward with froth, while impurities remain behind. Thus, the ore gets separated and concentrated. \[ \boxed{\text{Sulphide ores} \rightarrow \text{Froth flotation method}} \]

Step 2: Analyzing the remaining methods.

• Magnetic separation is used when either ore or impurity is magnetic.
• Hand picking is used for large-sized impurities that can be manually removed.
• Washing or hydraulic separation is based on density differences. These methods are not specifically suitable for sulphide ores. Therefore, the correct answer is: \[ \boxed{(3)\ \text{Froth flotation}} \]