Other minerals

Among the other minerals, the most important representatives of carbonates, sulfides, sulfates, and chlorides are summarized in Table 1.4. 

Carbonates with simple Carbonates CaCO, Calcite 

Hydrated carbonate Na2CO3 10H2O Natron, native soda 

Hydrated phosphates Phosphates FeP04 2H20 Strengite 

The steady-state luminescence of Pr + in minerals was found only in scheel-ite, where the hne near 480 nm has been ascribed to this center (Gorobets and Kudrina 1976) and possibly in fluorite (Krasilschikova et al. 1986). The luminescence of Pr in minerals is difficult to detect because its radiative transitions are hidden by the stronger lines of Sm in the orange range of 600-650 nm, Dy in the blue range of 470-490 nm and Nd in the near IR (870-900 nm). In order to extract the hidden Pr lines time-resolved luminescence was applied. The fact was used that Pr usually has a relatively short decay time compared to its competitors Dy , Sm and Nd, especially from the Po level. In order to correct identification of Pr lines in minerals several of them were synthesized and artificially activated by Pr (Fig. 5.5). Besides, comparison has been made with CL spectra of synthetic minerals artificially activated by Pr (Blank et al. 2000). 

A large number of minerals, in addition to those already discussed, have been reported to occur in coal. Not all have been positively identified, and often it is impossible to determine from the reports whether the mineral was intimately associated with the coal or was in the rock units making up the roof, floor, or a parting within the seam. Most of these other minerals are of limited significance in coal utilization, but a few are worth noting. Authigenic apatite [calcium fluorochlorohydroxyphosphate, Cas(P04)3 F Cl OH] has been found in coal produced in widely separated areas of the world. 

Starik et al (1960) and Burkser etai(l962) determined the relative leachability of Th and Pb from pitchblende. Starik et al (1961) found the first decay product of to be easily leached from 

Experiments on heating thorianite and uranothorite in vacuum have shown that the lead is more easily extracted from metamict material than from the crystalline mineral (Robinson et al, 1963). See Fig. 2 for examples of uranothorite on a discordia plot from the study by Silver and Deutsch (1963). 

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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]. 

In addition to the collector, polyvalent ions may show sufficiently strong adsorption on oxide, sulfide, and other minerals to act as potential-determining ions (see Ref. 98). Judicious addition of various salts, then, as well as pH control, can permit a considerable amount of selectivity. 

The most common compound is sodium chloride, but it occurs in many other minerals, such as soda niter, cryolite, amphibole, zeolite, etc. 

Nickel is found as a constitutent in most meteorites and often serves as one of the criteria for distinguishing a meteorite from other minerals. Iron meteorites, or siderites, may contain iron alloyed with from 5 percent to nearly 20 percent nickel. Nickel is obtained commercially from pentlandite and pyrrhotite of the Sudbury region of Ontario, a district that produces about 30 percent of the world s supply of nicke. 

Gadolinium is found in several other minerals, including monazite and bastnasite, both of which are commercially important. With the development of ion-exchange and solvent extraction techniques, the availability and prices of gadolinium and the other rare-earth metals have greatly improved. The metal can be prepared by the reduction of the anhydrous fluoride with metallic calcium. 

Ytterby, a village in Sweden) Discovered by Mosander in 1843. Terbium is a member of the lanthanide or "rare earth" group of elements. It is found in cerite, gadolinite, and other minerals along with other rare earths. It is recovered commercially from monazite in which it is present to the extent of 0.03%, from xenotime, and from euxenite, a complex oxide containing 1% or more of terbia. 

In addition to the main acidulation reaction, other reactions also occur. Free calcium carbonate in the rock reacts with the acid to produce additional by-product calcium compounds and CO2 gas which causes foaming. Other mineral impurities, eg, Fe, Al, Mg, U, and organic matter, dissolve, the result being that the wet-process acid is highly impure. 

The same moisture content of the produced cake can be obtained in shorter dewatering times if higher pressures are used. If a path of constant dewatering time is taken, moisture content is reduced at higher pressures with a parallel increase in cake production capacity. This is an advantage of pressure filtration of reasonably incompressible soHds like coal and other minerals. 

Flotation. The method of mineral separation in which a froth created in water by a variety of reagents floats some finely cmshed minerals, whereas other minerals sink. 

Ores which comprise a variety of minerals are, as a rule, heterogeneous. An ore body is usually named for the most important mineral (s) in the rock, referred to as value minerals, mineral values, or simply values. Some minerals contain metals, which are extracted by concentration and smelting. Other minerals, such as diamond, asbestos (qv), quartz (see Silicon COMPOUNDS), feldspars, micas (see Mica), gypsum, soda, mirabillite, clays (qv), etc, maybe used either as found, with some or no pretreatment, or as stock materials for industrial compounds or building materials (qv) (3). 

Sulfur is unusual compared to most large mineral commodities in that the largest portion of sulfur is used as a chemical reagent rather than as a component of a finished product. Its predominant use as a process chemical generally requires that it first be converted to an intermediate chemical product prior to use in industry. In most of the ensuing chemical reactions between these sulfur-containing intermediate products and other minerals and chemicals, the sulfur values are not retained. Rather, the sulfur values are most often discarded as a component of the waste product. 

Agriculture is the largest industry for sulfur consumption. Historically, the production of phosphate fertilizers has driven the sulfur market. Phosphate fertilizers account for approximately 60% of the sulfur consumed globally. Thus, although sulfur is an important plant nutrient in itself, its greatest use in the fertilizer industry is as sulfuric acid, which is needed to break down the chemical and physical stmcture of phosphate rock to make the phosphate content more available to plant life. Other mineral acids, as well as high temperatures, also have the abiUty to achieve this result. Because of market price and availabiUty, sulfuric acid is the most economic method. About 90% of sulfur used in the fertilizer industry is for the production of phosphate fertilizers. Based on this technology, the phosphate fertilizer industry is expected to continue to depend on sulfur and sulfuric acid as a raw material. 

Tin does not react directly with nitrogen, hydrogen, carbon dioxide, or gaseous ammonia. Sulfur dioxide, when moist, attacks tin. Chlorine, bromine, and iodine readily react with tin with fluorine, the action is slow at room temperature. The halogen acids attack tin, particularly when hot and concentrated. Hot sulfuric acid dissolves tin, especially in the presence of oxidizers. Although cold nitric acid attacks tin only slowly, hot concentrated nitric acid converts it to an insoluble hydrated stannic oxide. Sulfurous, chlorosulfuric, and pyrosulfiiric acids react rapidly with tin. Phosphoric acid dissolves tin less readily than the other mineral acids. Organic acids such as lactic, citric, tartaric, and oxaUc attack tin slowly in the presence of air or oxidizing substances. 

A fermentation such as that of Pseudomonas dentrificans typicaby requires 3—6 days. A submerged culture is employed with glucose, comsteep Hquor and/or yeast extract, and a cobalt source (nitrate or chloride). Other minerals may be required for optimal growth. pH control at 6—7 is usuaby required and is achieved by ammonium or calcium salts. Under most conditions, adequate 5,6-dimethylben2imida2ole is produced in the fermentation. However, in some circumstances, supplementation maybe required. 

Hazards of Production. In most zinc mines, zinc is present as the sulfide and coexists with other minerals, especiaHy lead, copper, and cadmium. Therefore, the escape of zinc from mines and mills is accompanied by these other often more toxic materials. Mining and concentrating, usuaHy by flotations, does not present any unusual hazards to personnel. Atmospheric poHution is of Httle consequence at mine sites, but considerable effort is required to flocculate and settle fine ore particles, which would find their way into receiving waters. 

Zirconium occurs naturally as a siUcate in zircon [1490-68-2] the oxide baddeleyite [12036-23-6] and in other oxide compounds. Zircon is an almost ubiquitous mineral, occurring ia granular limestone, gneiss, syenite, granite, sandstone, and many other minerals, albeit in small proportion, so that zircon is widely distributed in the earth s cmst. The average concentration of zirconium ia the earth s cmst is estimated at 220 ppm, about the same abundance as barium (250 ppm) and chromium (200 ppm) (2). 

Normally, zircon sand is readily available as a by-product of mtile and ilmenite mining at ca 150 per metric ton. However, zircon and baddeleyite are obtained as by-products of their operations, and therefore, the supply is limited by the demand for other minerals. In 1974, when a use for zircon in tundish nozzles developed in the Japanese steel industry, a resulting surge in demand and stockpiling raised zircon prices to 500/t. Worldwide production by country is given in Reference 80. 

Chry sotile is a hydrated magnesium siHcate and its stoicliiometric chemical composition may be given as AIg2Si20 (0H)4 [12001 -29-5]. However, the geothermal processes wliich ield the chry sotile fiber formations usually involve the co-deposition of v arious other minerals. Tliese mineral contaminants comprise brucite [1317-43-7] (AIg(OH)2), magnetite [1309-38-2] (Fe O, calcite [13397-26-7] (CaCO ), dolomite [16389-88-1] (AIg,CaC02),... 

Instrumental Methods for Bulk Samples. With bulk fiber samples, or samples of materials containing significant amounts of asbestos fibers, a number of other instmmental analytical methods can be used for the identification of asbestos fibers. In principle, any instmmental method that enables the elemental characterization of minerals can be used to identify a particular type of asbestos fiber. Among such methods, x-ray fluorescence (xrf) and x-ray photo-electron spectroscopy (xps) offer convenient identification methods, usually from the ratio of the various metal cations to the siUcon content. The x-ray diffraction technique (xrd) also offers a powerfiil means of identifying the various types of asbestos fibers, as well as the nature of other minerals associated with the fibers (9). 

For friction material appHcations, composite materials (qv) comprising glass or metallic fibers with other minerals have been developed. In such appHcations also, aramid and graphite fibers are effective, although the cost of these materials restricts their use to heavy duty or high technology appHcations (see Carbon fibers). 

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