What is the method of concentrating the ore which makes use of the difference in density between ore and impurities is called?

Levigation

The correct answer is option 2. Levigation.

Levigation is a method of ore concentration that relies on the principle of gravity separation. It's particularly useful when the ore and impurities have significantly different densities. Here's how the process typically works:

Crushing and Grinding: The raw ore is first crushed into smaller pieces and then ground into a fine powder. This increases the surface area of the ore particles, making it easier for the separation process to occur.

Mixing with Water: The powdered ore is then mixed with water to form a slurry or suspension. The water helps to suspend the particles and facilitates the separation process.

Settling: The slurry is allowed to settle in a container or a specially designed apparatus. Due to differences in density, the heavier ore particles settle at the bottom of the container, while the lighter impurities remain suspended in the water or rise to the top.

Decantation: Once the settling process is complete, the clear water above the settled ore particles is carefully decanted or drained off. This helps to remove the lighter impurities that have floated to the top

Collection: The concentrated ore particles at the bottom of the container are then collected and further processed to extract the desired metal or mineral.

Levigation is particularly effective for separating heavier ores from lighter impurities like mud, sand, or clay. It's a relatively simple and cost-effective method of ore concentration, especially when compared to more complex techniques like froth flotation or magnetic separation. However, it may not be suitable for all types of ores and impurities, and its efficiency can vary depending on factors such as particle size, density differences, and the nature of the ore.