Which technique uses dense media to separate heavy minerals from lighter material?

• A. Crushing
• B. Dense media separation
• C. Scrubbing
• D. X-ray fluorescence

Answer: (B)

Dense media separation is a gravity-based sorting method that uses a liquid with a carefully chosen density to separate minerals by their specific gravity. In practice, a dense medium (commonly a magnetite-water suspension) has its density tuned between the SG of the heavy target minerals and the lighter gangue. When material passes through the separator, the heavier minerals sink while the lighter material floats, creating two streams for further processing. This approach is especially useful in diamond processing because diamonds have a higher density than most surrounding rock, so with the right medium density you can recover diamonds while lighter material is discarded. Crushing breaks rock into smaller pieces, scrubbing cleans surfaces to aid liberation, and X-ray fluorescence analyzes composition rather than providing a density-based separation, so none of those methods achieves the same density-driven separation as dense media.