Compositions, minerals/ores

Comparative method. Sometimes, as in the analysis of a mineral, it may be impossible to prepare solid synthetic samples of the desired composition. It is then necessary to resort to standard samples of the material in question (mineral, ore, alloy, etc.) in which the content of the constituent sought has been determined by one or more supposedly accurate methods of analysis. This comparative method, involving secondary standards, is obviously not altogether satisfactory from the theoretical standpoint, but is nevertheless very useful in applied analysis. Standard samples can be obtained from various sources (see Section 4.5). 

Origin of ore fluids is constrained by (1) chemical compositions of ore fluids estimated by thermochemical calculations (section 1.3.2) and by fluid inclusion analyses, (2) isotopic compositions of ore fluids estimated by the analyses of minerals and fluid inclusions (section 1.3.3), (3) seawater-rock interaction experiments, (4) computer calculations on the seawater-rock interaction, and (5) comparison of chemical features of Kuroko ore fluids with those of present-day hydrothermal solutions venting from seafloor (section 2.3). 

Kajiwara, Y. (1973) Chemical composition of ore-forming solution responsible for the Kuroko type mineralization in Japan. Geochem. J., 6, 141-149. 

These deposits are characterized by polymetallic (Cu, Pb, Zn, Au, Ag, etc.) mineralization and formation in extensional stress fields. Ore fluids responsible for these ore deposits are dominated by seawater origin, considering isotopic and chemical composition of ore fluids. 

The (compositionally) simplest mineral class comprises the native elements, that is, those elements, either metals or nonmetals that occur naturally in the native state, uncombined with others. Native gold, silver, and copper, for example, are metals that naturally occur in a ductile and malleable condition, while carbon - in the form of either graphite or diamond -and sulfur are examples of nonmetallic native elements. Next in compositional complexity are the binary minerals composed of two elements a metal or nonmetallic element combined with oxygen in the oxides, with a halogen - either fluorine, chlorine bromine, or iodine - in the halides, or sulfur, in the sulfides. The oxide minerals, for example, are solids that occur either in a somewhat hard, dense, and compact form in mineral ores and in rocks, or as relatively soft, unconsolidated sediments that melt at moderate to... 

Oxide copper ores. In oxide ores copper is predominantly malachite with significant quantities of cobalt oxides. According to the mineral composition, these ores can be... 

This hydroxamate is selective towards calcite, fluorite and sericite. The yttrium group minerals that contain zircon also have highly complex mineral compositions. These ores contain fergusonite, euxenite and priorit besides other minerals that contain REO. Such deposits are found in Northern Canada (Thor Lake). 

The combined effects of /02. nd pH variation on the sulfur isotopic compositions of ore-forming minerals are shown in figure 11.42 for a temperature of 250 °C and 0%o. The dashed lines delineate the stability limits of con-... 

Figure 11.42 elucidates in a rather clear fashion the marked control exerted by the chemistry of the fluid on the sulfur isotopic compositions of ore-forming minerals. At the T and conditions dehneated in the figure, an increase in... 

The indirect method of deducing the isotope composition of ore fluids is more frequently used, because it is technically easier. Uncertainties arise from several sources uncertainty in the temperature of deposition, and uncertainty in the equations for isotope fractionation factors. Another source of error is an imprecise knowledge of the effects of fluid chemistry ( salt effect ) on mineral-water fractionation factors. 

II. Mineral assemblages and the composition of ore-forming fluids. Econ. Geol. 60, 1101 — 1166 (1965)... 

The compositions of ore minerals and other raw materials used as sources of metals are shown in Table I. 

The corrosion process of bronze metal which is buried in soil is described in a manner similar to the weathering of mineral ores. The factors that affect the corrosion include the composition of the metal. 

The beneficiation of raw potash ore into marketable products, similar to potash mining operations, requires a somewhat efferent scheme and equipment for each processing plant. The ore composition (mineralogy), ore grade (K2O content), liberation size (amount of masd-mum particle size required to attow separation of the different minerals), and type and amount of slimes (insolubles such as clay, anhydrite, dolomite, silica, etc.) are different for every deposit, and perhaps may be h W variable writhin a single deposit. Accordingly, themodr, ern potash processir plant must have an ef ient, hic y versatile process to accommodate variations in the feed yet still maintain product quality at as low a production cost as possible. 

Edentate and other anilines can be used to adjust the ionic composition of ore pulp. Therefore, they can be used as depressant to improve the selectivity of mineral in flotation process. The depressant CYQUEST comprises amino acids and anilines. The flotation results of mineral using CYQUEST are listed in Table 4.3. 

Today chemistry is often combined with other sciences, such as geology and physics, to form cross-disciplines such as geochemistry and physical chemistry. Geochemistry is the study of the chemical composition of ores, soils, and minerals of the snrface of the Earth and other planets. Physical chemistry is the study of the physical nature of chemical systems, including energy changes. 

Starch is a polysaccharide found in many plant species. Com and potatoes are two common sources of industrial starch. The composition of starch varies somewhat in terms of the amount of branching of the polymer chains (11). Its principal use as a flocculant is in the Bayer process for extracting aluminum from bauxite ore. The digestion of bauxite in sodium hydroxide solution produces a suspension of finely divided iron minerals and siUcates, called red mud, in a highly alkaline Hquor. Starch is used to settle the red mud so that relatively pure alumina can be produced from the clarified Hquor. It has been largely replaced by acryHc acid and acrylamide-based (11,12) polymers, although a number of plants stiH add some starch in addition to synthetic polymers to reduce the level of residual suspended soHds in the Hquor. Starch [9005-25-8] can be modified with various reagents to produce semisynthetic polymers. The principal one of these is cationic starch, which is used as a retention aid in paper production as a component of a dual system (13,14) or a microparticle system (15). 

A limited number of rare-earth minerals are mined for large-scale rare-earth production mona2ite, bastnaesite, loparite [12173-83-OJ, xenotime [13817-22-6]. In addition, siace the 1980s rare-earth-containing clays called ionic ore are mined ia China. Table 4 shows the rare-earth composition of typical mineral concentrates. 

Flow Sheets. AH minerals processing operations function on the basis of a flow sheet depicting the flow of soHds and Hquids in the entire plant (6,13,14). The complexity of a flow sheet depends on the nature of the ore treated and the specifications for the final product. The basic operations in a flow sheet are size reduction (qv) (comminution) and/or size separation (see Separation, size), minerals separation, soHd—Hquid separation, and materials handling. The overaH flow sheet depends on whether the specification for the final mineral product is size, chemical composition, ie, grade, or both. Products from a quarry, for example, may have a size specification only, whereas metal concentrates have a grade specification. 

The economic importance of an ore deposit itself is largely affected by mineral or metal prices. Mine closures and reopenings are a common event in the mineral iadustry for this reason. Economics can also be affected by the ore composition, for example, by unacceptable levels of penalty elements ia the ore. The assessment of overall economics of exploiting a given ore deposit is similar to that for any large-scale industry. The various cost components are those associated with equipment, labor, utiUties, contingencies, operation and production, transportation, working capital, suppHes, maintenance. 

Rubidium is found widely dispersed in potassium minerals and salt brines. LepidoHte [1317-64-2] a lithium mica having the composition KRbLi(0H,F)Al2Si20 Q, contains up to 3.5% Rb20 and is the principal source of the element. An ore that is basically poUucite [1308-53-8] ... 

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