Froth flotation, recycling technology

Froth flotation is used to raise the low mineral concentrations in ores to concentrations that can be more economically processed. A concentration of 25-30% is suitable for economical smelting of copper. The froth flotation technique was originally developed in about 1910 to raise the copper concentrations of the strip-mined ores of Bingham Canyon, near Salt Lake City [9], and was further perfected for the differential separation of lead, zinc, and iron sulfides at Trail, B.C., at about the same time [10]. Flotation technologies are now widely used for separations such as the beneficiation of low grade Florida phosphate ores from 30-40% to 60-70% concentrations of calcium phosphate (BPL), and the separation of about 98% potassium chloride from sylvinite, a natural mixture of potassium and sodium chlorides. It is also used for bitumen separation from tar sand, removal of slate from coal, and removal of ink from repulped paper stock preparatory to the manufacture of recycled paper stock. More details of these separations are discussed in the relevant chapters. 

By far, the largest technological application of liquid foams is in mineral froth flotation, and this process uses a substantial fraction of the world production of amphiphiles. Froth flotation is also used in other separation processes such as the deinking of recycled paper. Other uses of liquid foams include fire fighting, cleaning processes, drinks such as champagne or beer froth, foods such as whipped cream or egg white, and preparation of solid foams after solidification of the liquid continuous phase. 

Argoime National Laboratory has developed a plastics separation system based on froth flotation. A series of six tanks is used, each with a specific function, depending on the plastic being recovered. The chemical solutions in each tank are chosen for the particular apphcation. It has been used for recovering selected plastics from automobile shredder residue, disassembled car parts, industrial scrap plastics, and consumer electronics. Argonne claims it is the only technology that can successfully recycle ABS with a purity greater than 99 percent. ... 

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