What is the method of separating gold / black sand from magnetite ? Can a box of iron nails and steel needles be separated? How and why?
The most popular method of separating gold is a gravity separation, which includes the use of gravity force for recovery components having different specific weight. Since the gold is the heavier than magnetite (Fe3O4), its particles can be isolated by shaking the powdered sample in water on the metal surface. Iron nails and needles can be isolated by using the gravity method, because they have different masses of particles which results in the different velocities of sedimentation in liquid. The procedure used for separation is based on the flotation method (gravity separation in fluid). It involves shaking the mixture in cylinder with an oil and collecting the particles found in the bottom side (enriched with nails) and in the upper side (enriched with needles), respectively.