Major Ore Minerals

Average rare earth content of the major ore minerals (%) [2],... 

Hematite, a-Fe203, is a major ore mineral. It is isostructural with corundum and it seems reasonable to expect that it wonld slip on similar systems. There have been few deformation experiments on single crystals, however, and even fewer direct observations of dislocations in hematite. 

The minerals on which the work was performed during the nineteenth century were indeed rare, and the materials isolated were of no interest outside the laboratory. By 1891, however, the Austrian chemist C. A. von Welsbach had perfected the thoria gas mantle to improve the low luminosity of the coal-gas flames then used for lighting. Woven cotton or artificial silk of the required shape was soaked in an aqueous solution of the nitrates of appropriate metals and the fibre then burned off and the nitrates converted to oxides. A mixture of 99% ThOz and 1% CeOz was used and has not since been bettered. CeOz catalyses the combustion of the gas and apparently, because of the poor thermal conductivity of the ThOz, particles of CeOz become hotter and so brighter than would otherwise be possible. The commercial success of the gas mantle was immense and produced a worldwide search for thorium. Its major ore is monazite, which rarely contains more than 12% ThOz but about 45% LnzOz. Not only did the search reveal that thorium, and hence the lanthanides, are more plentiful than had previously been thought, but the extraction of the thorium produced large amounts of lanthanides for which there was at first little use. 

As noted already, epithermal vein-type deposits are classified primarily on the basis of their major ore-metals (Cu, Pb, Zn, Mn, Au and Ag) into the gold-silver-type and the base-metal-type. Major and accessory ore-metals from major vein-type deposits in Japan were examined in order to assess the possible differences in the metal ratios in these two types of deposits (Shikazono and Shimizu, 1992). Characteristic major ore-metals are Au, Ag, Te, Se and Cu for the Au-Ag deposits, and Pb, Zn, Mn, Cu and Ag for the base-metal deposits (Shikazono, 1986). Accessary metals are Cd, Hg, Tl, Sb and As for the Au-Ag deposits and In, Ga, Bi, As, Sb, W and Sn for the base-metal deposits (Table 1.22, Shikazono and Shimizu, 1992). Minerals containing Cu, Ag, Sb and As are common in both types of deposits. They are thus not included in Table 1.22. 

Most major ore deposits that intersect the earth s surface have probably been identified. To satisfy the increasing demand for metals, buried deposits lacking primary surface expressions have become targets for exploration. Future discoveries of economic mineral deposits increasingly rely on the identification of subtle, secondary expressions of deeply buried metal bearing systems (Govett 1976 Kelly et al. 2006). 

Mixed copper sulphide oxide ores. These contain varieties of both sulphide and oxide minerals, and are the most complex copper-bearing ores from a beneficiation point of view. The major copper minerals present in this ore type include bomite, chalcocite, covellite, malachite, cuprite and chrysocolla. In some cases, significant amounts of cobalt minerals are also present in this ore. 

There are only few operations treating mixed lead zinc sulphide oxide ores that contain barite-calcite gangue minerals. A typical example of such an operation is the Tynagh oxide complex in Ireland [11]. In this deposit, the oxide ores are generally located at the bottom and at the ends of the sulphide mud ores. The major gangue mineral is barite (large quantities) and minor amounts of clay. This ore assays 8.5% Pb(total), 6% Pb(oxide), 6.8% Zn(total) and 5% ZnO. 

This ore type is found in South America (Peru). The major gangue minerals are goethite, Fe-hydroxides, dolomite, siderite and clay mineral. 

Collectors from the PM series were specifically developed for beneficiation of niobium ores that contain nepheline/cyanite as the major gangue minerals. The collector is composed of a mixture of phosphate ester collector (SM15, Clariant) and phosphonic acid treated with octanol. From an ore that assays 0.5% Nb20s, a concentrate grade of 49% Nb205 at a recovery of 73% was achieved. 

Cationic flotation of tantalite columbite has also been studied on several ore types that contain tourmaline, feldspar and muscovite as the major gangue minerals [3], The effect of aliphatic mono-amine on flotation of Ta/Nb is presented in Figure 23.3. 

The ore used in this example contained a mixture of pyrochlore and columbite as the major niobium minerals. The tantalum is mainly associated with columbite. The major gangue minerals present in this ore were soda and potassium feldspars with small amounts of mica and quartz. Beneficiation of this ore using cationic flotation, normally employed for flotation of niobium, was not applicable for this particular ore, since most of the mica and feldspar floated with the niobium and tantalum. The effect of amine on Ta/Nb flotation is illustrated in Figure 23.9. The selectivity between Ta/Nb and gangue minerals using a cationic collector was very poor. 

The Mountain Pass (USA) operation treats a relatively complex ore. The major REO mineral is bastaenesite with minor amounts of synchisite, parasite and monazite. The major gangue minerals are calcite, barite, silicates, and dolomite. The amount of the individual gangue minerals in this ore are variable and change on a yearly basis. There are two major ore types treated at the Mountain Pass concentrator (a) high calcite ore (35-45% CaO) and (b) a high barite-dolomite ore (so-called brown ore). Barite also contains significant quantities of strontium. 

This ore is heavily weathered ore, with more than 30% of the bastnaesite contained in the -7 (iim fraction. The major host minerals present in this ore are barite and fluorite. Table 24.6 shows the chemical analyses of the ore used in various research studies. 

There are two major ore bodies the Stogargen (old deposit) and Zellnes deposits. These two deposits are quite different in mineral composition. Numerous studies have been carried out on these two ore types to provide support for the operating plant. 

The Sept lies ore contains economic quantities of apatite and ilmenite. About 6% of the titanium in this ore is represented by titanomagnetite. The major gangue minerals include feldspar, olivine, dolomite and aluminosilicate. This ore assayed 7.2% Ti02 and 4.25%... 

A large hard rock rutile deposit was discovered in central Chile. This ore is relatively complex with variable head grade of rutile ranging from 2% to 4% Ti02. The liberation of rutile occurs at about 100 mesh nominal size. The major gangue minerals present in this ore include feldspars, calcite and some silicates. 

Almost all rocks contain some aluminum in the form of aluminum silicate minerals found in clays, feldspars, and micas. Today, bauxite is the major ore for the source of aluminum metal. Bauxite was formed eons ago by the natural chemical reaction of water, which then formed aluminum hydroxides. In addition to the United States, Jamaica and other Caribbean islands are the major sources of bauxite. Bauxite deposits are found in many countries, but not all are of high concentration. 

Vanadium is recovered from several sources vanadium minerals, vanadium-bearing phosphates, boder residues, and spent vanadium catalysts. One major vanadium mineral is patronite, a greenish-black, amorphous sulfide ore used extensively for many years to produce vanadium. This mineral, found in Peru, has depleted gradually. The metal also is recovered commercially from carnotite and roscoelite. 

Kuroko deposits are massive-type ore deposits formed by the deposition of various sulfide minerals around submarine fumaroles. They are major ore deposits of Cu, Pb, and Zn in Japan. 

Major lead mineral in the ore samples identified as sulfides is galena (PbS). 

Ore samples identified as oxides are highly oxidized or gossan ores in which the major lead mineral is also galena. 

The major ore of zinc (though it occurs in numerous other minerals) is sphalerite, a form of ZnS usually found to also contain iron and commonly associated with galena (PbS). Cadmium is mostly found isomorphously replacing zinc in zinc minerals. To obtain metallic zinc from its ore, the ore is first calcined to ZnO and this is then roasted at ca. 1000°C with charcoal in the absence of air, whence the metal distills out. Cadmium can be separated from sulfate solutions of both zinc and cadmium by addition of zinc dust ... 

The overwhelming majority of ore minerals are characterized by very low solubilities in pure water, even at elevated temperatures (Wood and Samson, 1998). Given these low solubilities, it is not clear that pure water could transport sufficient quantities of ore substance to account for the origin of many ores by hydrothermal processes. However, the addition of suitable mineralizers... 

In contrast to the very restricted size of the soil-gas anomaly at Jabiluka, Zonghua and Yangfen (1981) describe broad anomalies associated with a buried skam Cu deposit near Shanghai, China. The ore body is confined to the contact zone of granodiorite and Palaeozoic and Mesozoic sedimentary rocks. The major sulphide minerals in the ore body are chalcopyrite, pyrite and molybdenite. Part of the deposit has been oxidised to limonite. The area is covered by 140-180 m of alluvium. A soil-gas survey of the area was complemented by a multielement study of soils including the determination of Hg. Significant anomalies of Hg in soil and soil gas occurred above the buried sulphide... 

Major faults of the Illinois Basin area are shown in Fig. 10. The southern portion of the basin is intensely faulted northeast-trending faults in southeast Illinois and northwest Kentucky are associated with the lllinois-Kentucky Huorspar district. A number of these faults in Mississippian limestone beds are mineralized with the ore minerals fluorite (CaF2), sphalerite, and galena, and with gangue minerals such as calcite and pyrite... 

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