Experience diving steel needles and copper coins on the water has similarities with the phenomenon, used in the mining industry for “enrichment” ores, i.e., to increase the content of valuable components. Technology knows many ways ores; one that we now have in mind and which is called “flotation”, is the most effective; it has been successfully applied even in cases when all others fail.
The essence of flotation (i.e., floating) consists in the following. Finely ground ore is loaded into a VAT of water and oily substances that can envelop the particles of the useful mineral thin films, are not wetted by water. The mixture is vigorously mixed with the air, forming a multitude of small bubbles of the foam. The particles of the useful mineral, clothed thin oily film coming into contact with the sheath air bubbles, stick to it and hang on the bubble and makes them up like a balloon in the atmosphere raises the gondola. Particles as waste rock, not clothed oily substance, not stick to the membrane and remain in the liquid.
How is flotation.
It should be noted that the air bubble foam much bigger than mineral particle, and its buoyancy is sufficient for the entrainment of solid grains up. Eventually the particles of the useful mineral, almost all are in the foam covering the liquid. The foam is removed and sent to further processing to obtain the so-called “concentrate”, which is ten times richer in useful minerals than the original ore.
The technique of flotation designed carefully so that the proper selection primitively liquids can be separated every useful minerals from the waste rock of any composition.
The idea flotation resulted not only theory, but careful observation random fact. At the end of last century, the American teacher (Curry, Everson), erasing contaminated with oil bags, which were stored previously, copper pyrites, drew attention to the fact that grains of pyrite surface with soapy foam. This was the impetus for the development of the flotation method.