Separations by flotation

Production of KCl at the Wendover, Utah operation employs a large 7000 acre complex of solar ponds. Both shallow brine wells and deeper wells are used to pump brine into the pond complex. In the preconcentration ponds water is evaporated and sodium chloride is crystallized. Later the brine is transferred to production ponds where sylvinite is deposited. Brine is then transferred to other ponds where camaUite is crystallized. Sylvinite is removed from drained ponds with self-loading scrapers and taken to the plant were KCl is separated by flotation with an amine oil collector. The camaUite,... 

Sulfide Ores ores. In the Zairian ores, cobalt sulfide as carroUite is mixed with chalcopyrite and chalcocite [21112-20-9]. For processing, the ore is finely ground and the sulfides are separated by flotation (qv) using frothers. The resulting products are leached with dilute sulfuric acid to give a copper—cobalt concentrate that is then used as a charge in an electrolytic cell to remove the copper. Because the electrolyte becomes enriched with cobalt, solution from the copper circuit is added to maintain a desirable copper concentration level. After several more steps to remove copper, iron, and aluminum, the solution is treated with milk of lime to precipitate the cobalt as the hydroxide. 

Mixed liberated particles can be separated from each other by flotation if there are sufficient differences in their wettability. The flotation process operates by preparing a water suspension of a mixture of relatively fine-sized particles (smaller than 150 micrometers) and by contacting the suspension with a swarm of air bubbles of air in a suitably designed process vessel. Particles that are readily wetted by water (hydrcmhiric) tend to remain in suspension, and those particles not wetted by water (hydrophobic) tend to be attached to air bubbles, levitate (float) to the top of the process vessel, and collect in a froth layer. Thus, differences in the surface chemical properties of the solids are the basis for separation by flotation. 

Floating matter Matter which passes through a 2000 micron sieve and separates by flotation for an hour. 

When the sulfide ore carroUite, CuS C02S3, is the starting material, first sulfides are separated by flotation with frothers. Various flotation processes are applied. The products are then treated with dilute sulfuric acid producing a solution known as copper-cobalt concentrate. This solution is then electrolyzed to remove copper. After the removal of copper, the solution is treated with calcium hydroxide to precipitate cobalt as hydroxide. Cobalt hydroxide is filtered out and separated from other impurities. Pure cobalt hydroxide then is dissolved in sulfuric acid and the solution is again electrolyzed. Electrolysis deposits metallic cobalt on the cathode. 

In most industrial processes, copper is produced from the ore chalcopyrite, a mixed copper-iron sulfide mineral, or from the carbonate ores azurite and malachite. The extraction process depends on the chemical compositions of the ore. The ore is crushed and copper is separated by flotation. It then is roasted at high temperatures to remove volatile impurities. In air, chalcopyrite is oxidized to iron(ll) oxide and copper(ll) oxide ... 

A principal plastic reclaiming process used was developed in the Netherlands by a resin manufacturing firm. In this process, after removal of labels and base cups by machine, the bottles (clear or green) are color sorted and granulated. The PET flake is then washed to remove glue. Closure material is separated by flotation from Hie PET. The remaining PET is dried and sifted for fines and then is ready for reuse. 

Parent resorcin[4]arenes also show Cs selectivity in extraction from alkaline media (pH 12), for example, into benzene.24 With long alkyl chains appended to the bridging carbon atom, separation by flotation is possible. 

Solid-liquid separation by flotation may be achieved by gravity alone or induced by dissolved-air or vacuum techniques. The mechanisms and driving forces are similar to those found in sedimentation, but the separation rate and solids concentration can be greater in some cases. 

Polymeric forms of the coagulants (e.g., polyaluminum chloride) are rather useful because they require lower alkalinity consumption and the concomitant lower production of sludge. Once the colloids are destabilized, slow stirring can also help them merge and form relatively large aggregates called floes (hence the name flocculation) that are separated from water by settlement and filtration. In some cases, these floes can be attached to purposefully generated gas bubbles and separated by flotation. 

Figure 5.43. Elementary act of separation by flotation hydrophobic particles, hydrophilic particles. The former adhere to ascending air bubbles.

A variety of industrial equipment has been used to carry out the flocculation process and the separation of the flocculated materials producing a well-defined sludge suspension layer, which can be removed. Some plant operates with sludge feedback to enable more efficient adsorption. Sludge flocks can also be separated by flotation. 

The magmatic deposits (Kola Russia, Phalaborwa South Africa) are extracted in open cast mines or underground mines. They have a high phosphate content and are free of organic impurities. The phosphate ore is extracted together with gangue, which is separated by flotation. 

K. E. Bremmell, D. Fomasiero, and J. Ralston, Pentlandite-lizardite interactions and implications for their separation by flotation, Colloids and Surfaces—Physicochemical and Engineering Aspects, 252(2-3) (2005). 

To determine Bi203 (-0.01%) in bismuth, the metal is dissolved in mercury, and the undissolved oxide is separated by flotation [7]. A co-precipitate of traces of bismuth with Fe(OH)3 (pH 4) is separated by flotation with the use of a surfactant [8]. 

Phenylethylenephosphonic acid and a frothing agent were added to the reaction mixture, after the reduction of gold(III) by SnCE, and Au was separated by flotation with the use of nitrogen gas [32]. 

In a sensitive flotation-spectrophotometric method (e = 3.4-10 ), a compound [(MB )(Hgl3)]-3[(MB )(l3)] (MB = Methylene Blue) is separated by flotation with cyclohexane from a 0.4 M HCl medium, containing T and MB then it is washed with water and dissolved in methanol [55]. Mercury has also been determined spectrophotometrically after separation (by flotation with cyclohexane) from solutions containing the iodide complex and Brilliant Green (e = 5.96-10 ) [56]. 

Xanthene reagents, such as Bromopyrogallol Red (BPR) (formula 4.19) [141-143] and Gallein (formula 4.18) have been used for determination of W in the presence of surfactants. The W complex with BPR and diphenylguanidine was separated by flotation with petroleum ether and was dissolved in butanol (e = 8.4-10" at 610 nm) [143]. 

The molybdophosphate anion has been associated, in a HCl medium, with a cationic complex of Co with 5-Cl-PADAP. The sparingly soluble associate has been separated by flotation with butyl acetate and dissolved in methanol (e = 3.4-10 at 560 nm) [62]. 

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