Chalcopyrite, 856 table

Copper ore minerals maybe classified as primary, secondary, oxidized, and native copper. Primaryrninerals were concentrated in ore bodies by hydrothermal processes secondary minerals formed when copper sulfide deposits exposed at the surface were leached by weathering and groundwater, and the copper reprecipitated near the water table (see Metallurgy, extractive). The important copper minerals are Hsted in Table 1. Of the sulfide ores, bornite, chalcopyrite, and tetrahedrite—teimantite are primary minerals and coveUite, chalcocite, and digenite are more commonly secondary minerals. The oxide minerals, such as chrysocoUa, malachite, and azurite, were formed by oxidation of surface sulfides. Native copper is usually found in the oxidized zone. However, the principal native copper deposits in Michigan are considered primary (5). 

Sulfide scales deposited on the casing wall were found. The minerals of the. scales are listed in Table 2.7 (Imai et al., 1988, 1996 Nitta et al., 1991). The chemical compositions of sphalerite, chalcopyrite, and tetrahedrite are given in Table 2.7. 

Main opaque minerals are chalcopyrite, pyrite, pyrrhotite, sphalerite and bornite (Table 2.22). These minerals commonly occur in massive, banded and disseminated ores and are usually metamorphosed. Hematite occurs in red chert which is composed of fine grained hematite and aluminosilicates (chlorite, stilpnomelane, amphibole, quartz) and carbonates. The massive sulfide ore bodies are overlain by a thin layer of red ferruginous rock in the Okuki (Watanabe et al., 1970). Minor opaque minerals are cobalt minerals (cobaltite, cobalt pentlandite, cobalt mackinawite, carrollite), tetrahedrite-tennantite, native gold, native silver, chalcocite, acanthite, hessite, silver-rich electrum, cubanite, valleriite , and mawsonite or stannoidite (Table 2.22). 

Table 1. Mean dissolved concentrations for chalcopyrite and pentlandite periods of kinetic tests... 

The formation of sulphur on chalcopyrite surface would be expected to occur at 0.15 V at pH = 6 by assuming [Fe ] = 10" mol/L according to reaction (2-8), 0.08 V at pH = 8 and -0.1 V at pH = 11 according to reaction (2-9). While flotation does begin very near these potential for the experimental conditions reported by some authors as shown in Table 2.1. 

It may be seen from the results in Chapter 2 that the floatability descends in the order of chalcopyrite galena, pyrrhotite, bomite, arsenopyrite and pyrite in self-induced collectorless flotation but the order is just reversed in sodium sulphide-induced flotation, the phenomena of which may be explained in the light of their rest potential as shown in Table 3.1. 

The type and addition of frother are found to have a pronounced effect on the collectorless floatability of chalcopyrite (Heyes and Trahar, 1977). The recovery of collectorless flotation of chalcopyrite is much higher using PPG40 than amyl alcohol. The effects of several frothers on the collectorless flotation of some minerals have been tested and the results are presented in Table 10.1. It further provides the evidence that the type of frother produces a markable influence on collectorless flotation of sulphide minerals. The frothers with lower surface tension are more effective in enhancing the recovery of collectorless flotation of sulphide minerals. 

Table 10.2 Separation results of collectorless flotation of a mixture of chalcopyrite, galena and quartz (Feng et al., 1991)...

Table 10.3 Eh control separation of a mixed concentration of collector flotation of chalcopyrite-galena ore (Wang, 1992a,b)...

Figure 10.11 presents the sehematic flowsheets of potential controlled flotation separation to recover chalcopyrite and pyrite from a copper-sulphur ore. Flowsheet I is collectorless flotation of chalcopyrite and then collector floatation of pyrite. Flowsheet II is collectorless flotation of chalcopyrite and then sodium sulphide-induced flotation of pyrite. Batch flotation results are illustrated in Table 10.5. It is evident that both flowsheets are suitable for flotation separation of copper-sulphur ore. The feed ore assayed 0.38% Cu and about 6% S, the copper concentrate obtained assayed 18%- 19% Cu with a recovery of 89%. For sulphur concentrate, the grade is 37%-43% S with a recovery of 82% - 85%. Interestingly, flie grade of sulphur concentrate is higher using sodium sulphide induced flotation than collector flotation. 

Table 10.7 shows the flotation separation results of a mixture of chalcopyrite and arsenopyrite. It may be seen that at high pH, the chalcopyrite can be separated effectively from arsenopyrite by controlling the potential at about 280 mV. The floated product assays 29.4% Cu and recovery is 93.48%. 

Table 10.7 Separation results of the mixture of chalcopyrite and arsenopyrite (111) by butyl xanthate (1.5 x 10 mol/L) induced flotation...

Freibergite is the dominant host for Ag in the HRMZ, wherein Ag concentrations increase stratigraphically upwards with 99% of Ag hosted by type 5 mineralization (Table 1). Silver-bearing chalcopyrite contains 40% of the Ag in type 2a mineralization and 13% in type 3 where chalcopyrite contains up to 7.29 wt.%. Within both freibergite and chalcopyrite, Ag directly substitutes for Cu in the mineral lattice. Freibergite within the HRMZ is also consistently enriched in Ag (21.9 to 38.5%) compared to many other VMS deposits (e.g. Kidd Creek Hannington et al. 1999, Heath Steele Chen Petruk 1980, Rosebery Huston et al. 1996). 

The standard device comprises a thin CdS buffer layer as described above. It is believed that market acceptance of chalcopyrite-based photovoltaics could be improved by introducing a Cd-free buffer layer. There may also be cost benefits in view of the cost associated with (occupational) safety, handling of toxic waste in production, and recycling of modules at their end of life. Research has identified Cd-free materials well suited for alternative buffer layers. They can be deposited by CBD in analogy to the standard CdS buffer layers or by other processes. In particular, dry processes are attractive because they offer a better compatibility with the other process steps used for the remainder of the module. Ultimately, the best solution would be to omit the buffer layer altogether in favor of a direct chalcopyrite-sputiered/MOCVI) ZnO junction. Here we will limit the discussion to the state of these latter direct junctions and to ZnO-based buffer layers (Table 9.1). Results achieved with other materials can be found in the literature [67,68]. 

Table 9.1. Performance of ZnO/chalcopyrite solar cells without buffer layer...

Conventional mining is both of historical interest and is still used to produce nearly a quarter of the world s sulfur (Table 9.2). Mining brings to the surface lumps of either a volcanic or one of the many pyritic forms of sulfur. Some of the pyritic forms are pyrite (FeSi) itself, chalcocite (CuiS), and chalcopyrite (CuFeSi). The sulfur content of the raw mineral is usually 25-35%, but may run as high as 50%. To obtain the sulfur in a separated form, the original procedure was to pile the lumps of ore outside and seal these with clay or earth. Burning a part of the contained sulfur sealed into these mounds, with careful control of the air generated sufficient heat to melt any elemental sulfur present, and thermally decompose the pyrite (Eqs. 9.1-9.3) [10]. 

The preparation and characterization of the two phases Caio- Si,2-2 As,(, and Caio, Si]2- Pi6 (0.66 X 2.50) have been described.Their structures are isotypic and crystallize with monoclinic symmetry, of space group they may be related to a slightly distorted NaCl-type. Their unit-cell parameters are included in Table 27. A comparison of the different methods of crystal growth of ZnSiP2, ZnSiAs2, and CdGeAs2 (chalcopyrite structures) has also been undertaken. " ... 

Table 4.2 lists the values of rest potential for a few minerals in potassium ethyl xanthate solutions (6.25 X 10 mol/1, pH 7) and infrared identifications of surface reaction products (Allison et al., 1972). Only those minerals such as chalcopyrite and pyrite have surface reaction product of dixanthogen. 

The molecular structures of several new collectors have been designed as shown in Table 5.37 [21]. The carbon numbers of non-polar group required for given collector-mineral systems are also calculated and given in Table 5.37. The results in Table 5.38 show that the collector synthesized according to the calculated carbon numbers of non-polar group is the best one for given collector-mineral systems. These new collectors can be used as selective collectors for flotation separation of chalcopyrite from sphalerite, cassiterite or wolframite from calcite, malachite from smithsonite and calcite. 

TABl 4. Comparison of Average Heats of Atomization (Hs, in kcal/g-atom) and Energy Gaps (Eg, in eV) of Some Chalcopyrites (Elj Structure) of General Formula n-IV-Vz... 

The matrix of the till on Mt. Sirius is composed of quartz, plagioclase, K-feldspar, kaolinite, montmoril-lonite, and illite (Hagen 1988, p. 22). The sand-size fractions (1.0-0.0625 nun) contain heavy minerals including pyroxene, hornblende, garnet, tourmaline, rutile, zircon, apatite, sphene, magnetite, ilmenite, hematite, pyrite, and chalcopyrite. A bulk sample of the heavy mineral fraction of till on ML Sirius in Table 19.1 is composed primarily of iron, titanium, and manganese with lesser concentrations of chromium, zinc, copper, and nickel (Hagen 1988). Additional analyses of the heavy-mineral fractions of till in the Transantarctic Mountains were published by Faure et al. (1995). 

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