An Industrial Separation – Froth Flotation The rocks of the lithosphere are the source of many useful substances such as metals. Rocks are composed of mixtures of minerals. These Rocks are called ores and may contain one or more useful mineral quantities that make it profitable to mine or extract. What is froth floatation? Properties of the mixture The Process Prior to the froth flotation, the ore is reduced to very small particle sizes by crushing and grinding operations. The bubbles are produced by stirring and blowing air into a mixture of the powdered ore, water and frothing reagents, in a big tank. The minerals stick to the froth and rise to the surface where they are skimmed off. The water and chemicals are removed, leaving concentrated mineral that is treated chemically to extract the metals. {draw:frame} *The P*roducts and *U*ses After separation, metal minerals may be treat further o remove unwanted metal from the compound. The metals have many uses; e.g. Lead is used in making lead-acid batteries, zinc for galvanising steel and the cases of dry cell batteries. The gangue does not cling to the bubbles and so it sinks to the bottom and is removed. The wet gangue aresent to “tailings” in a dam to evaporate in which they accumulate and are eventually disposed of safely. Tailings may be returned underground to fill mines that are no longer in use. Some tailings may still contain small percentages of the metal minerals and they may be further treated at a later date when the technology improves. Issues associated with wastes The wastes left over from the Froth Flotation process are called Tailings. These are the dry solid wastes of gangue and they may still contain small amounts of toxic lead and zinc so they must be safely disposed. The tailings may also contain toxic substances such as (arsenic from goldmines or copper salts from copper mines). Therefore care must be taken that the tailings dam is lined to...