Potassium chloride flotation

Medemblik, L. 1991. "Treatment of Qay Suspensions in MDPS s Potassium Chloride Flotation Plant, IN Preprints of the XVII Internationa/ Mineral Processing Congress, pp. 104-120, Dresden, Germany. 

The examples in the preceding section, of the flotation of lead and copper ores by xanthates, was one in which chemical forces predominated in the adsorption of the collector. Flotation processes have been applied to a number of other minerals that are either ionic in type, such as potassium chloride, or are insoluble oxides such as quartz and iron oxide, or ink pigments [needed to be removed in waste paper processing [92]]. In the case of quartz, surfactants such as alkyl amines are used, and the situation is complicated by micelle formation (see next section), which can also occur in the adsorbed layer [93, 94]. 

Potassium Chloride. The principal ore encountered in the U.S. and Canadian mines is sylvinite [12174-64-0] a mechanical mixture of KCl and NaCl. Three beneficiation methods used for producing fertilizer grades of KCl ate thermal dissolution, heavy media separation, and flotation (qv). The choice of method depends on factors such as grade and type of ore, local energy sources, amount of clay present, and local fuel and water availabiUty and costs. 

Froth Flotation. Froth flotation (qv) of potassium chloride from sylvinite ores accounts for ca 80% of the potassium chloride produced in North America and about 50% of the potassium chloride in Europe and the CIS. Fractional crystallisation and heavy-media processing account for the remaining amounts produced. Froth flotation has been described (6,16,17). 

Further upgrading of the potassium chloride content of the chloride salts recovered from the initial heavy-medium separation takes place in a second heavy-medium separation at a somewhat lower specific gravity than the first separation. Sodium chloride is discarded as a waste the enriched KCl fraction is sent to a flotation process where a final separation of KCl from NaCl is made. Mine-mn ore less than 1 mm that is not amenable to... 

Potassium chloride, 11 122 12 67 20 611-625. See also KCl-langbeinite ore chemical grades of, 20 62It compaction of, 20 621-625 corrosive effect on iron, 7 806 electrolysis of, 20 633 encapsulated, 16 453 froth flotation of, 20 615-616 mining, 20 613-615 refining, 20 615-621 as salt substitute, 22 819-820 separation from sodium chloride, 20 622 therapeutant for aquaculture in U.S.,... 

Large deposits of sylvinite (42.7% KCl, 56.6% NaCl) near Carlsbad, New Mexico, account for 85% of the potassium products produced in the U.S. The potassium chloride can be separated by either fractional crystallization or flotation. Potassium chloride is also obtained from the brines of Searles Lake, California. All these sources give potash (97% potassium chloride) with a 60% K2O equivalent for fertilizer use. A chemical-grade product can be obtained to a purity of 99.9% potassium chloride. Almost all potash produced is potassium chloride. Potash is used mainly as fertilizer (88%) with a small amount (12%) used in chemical manufacture. 

ACTIVATOR. 1. A substance that renders a material or a system reactive commonly, a catalyst. 2. A special use of this term occurs in the flotation process, where an activator assists the action of the collector. 3. An impurity atom, present in a solid, that makes possible the effects of luminescence, or markedly increases their efficiency. Examples are copper in zinc sulfide, and thallium in potassium chloride. See also Enzyme. 

Although flotation was developed as a separation process for mineral processing and applies lo the sulfides of copper, lead, zinc, iron-molybdenum, cobalt, nickel, and arsenic and to nonsullides, such as phosphates, sodium chloride, potassium chloride, iron oxides, limestone, feldspar, fluorite, chromite, tungstates, silica, coal, and rhodochrosilc, flotation also applies to nonmineral separations. Flotation is used in the water disposal field, particularly in connection with petroleum waste water cleanup. 

The raw minerals mined from natural deposits comprise mixtures of different specific minerals. An early step in mineral processing is to use crushing and grinding to free these various minerals from each other. In addition, these same processes may be used to reduce the mineral particle sizes to make them suitable for a subsequent separation process. Non-ferrous metals such as copper, lead, zinc, nickel, cobalt, molybdenum, mercury, and antimony are typically produced from mineral ores containing these metals as sulfides (and sometimes as oxides, carbonates, or sulfates) [91,619,620], The respective metal sulfides are usually separated from the raw ores by flotation. Flotation processes are also used to concentrate non-metallic minerals used in other industries, such as calcium fluoride, barium sulfate, sodium and potassium chlorides, sulfur, coal, phosphates, alumina, silicates, and clays [91,619,621], Other examples are listed in Table 10.2, including the recovery of ink in paper recycling (which is discussed in Section 12.5.2), the recovery of bitumen from oil sands (which is discussed further in Section 11.3.2), and the removal of particulates and bacteria in water and wastewater treatment (which is discussed further in Section 9.4). 

Deposits of sylvinite (43% by weight potassium chloride and 57% by weight sodium chloride) account for large amounts of naturally occurring potassium. The potassium chloride can be separated by either fractional crystallization or flotation. Brine is also a valuable source of potassium chloride. A small amount of potassium sulfate is isolated from natural deposits, and potassium nitrate is manufactured by two processes. 

Cationic surfactants have applications such as inhibiting the growth of bacteria, inhibiting corrosion, separating phosphate ore from silica and potassium chloride from sodium chloride (flotation agents), and they serve well as fabric softeners, antistatic agents, and hair conditioners. 

Potassium Chloride Recovery by Conventional Mining and Froth Flotation... 

FIGURE 6.6 Flow diagram of the separation of fertilizer grade potassium chloride (sylvite) from sylvinite by froth flotation in saturated brine. 

Froth flotation of the surface-sensitized pulp by vigorous aeration and agitation in saturated brine (density ca. 1.18 g/mL), first in a series of rougher cells with further refinement in cleaner units, produces a stable froth consisting almost entirely of beneficiated potassium chloride and an underflow of sodium chloride (particle densities of 1.984 and 2.165 g/mL), respectively. Potassium chloride recoveries from sylvinite by this procedure are 90 to 95% complete [22]. 

Potassium chloride as a component in fertilizers is specified in terms of its K2O equivalent. On this basis, 100% pure potassium chloride is equated to 63.18% K2O equivalent. The approximately 96% pure potassium chloride product of the flotation separation is thus equivalent to 60.7% K2O (see Chap. 9). Chemical grades correspond to the once-crystallized, soluble product of about 99.5% KCl, and 99.95% KCl, which is the Refined, twice crystallized material. The price differential, 60-62.4% K2O equivalent at 108-112 US /tonne, and 99.95% KCl at 115-137 US /tonne (1995 prices [30]) is sufficient to cover the cost of the additional processing for Chemical grade potash. 

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. 

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