Sphalerite, 856 table

Zinc ores are widely distributed throughout the world 55 zinc minerals are known (8—10). However, only those Hsted in Table 1 are of commercial importance. Of these, sphalerite provides ca 90% of the zinc produced today. Sulfide ores usually occur in the range of 2—12% zinc (average ca 4%) as mined. 

Dominant sulfides and sulfate minerals in the Osorezan area are pyrite, marcasite, orpiment, realgar, stibnite, krennerite, coloradoite, jordanite, wurtzite, sphalerite, cinnabar, and barite (Aoki, 1992b). H2S concentration of the Osorezan hot spring is very high, compared with the other Japanese geothermal waters (Table 2.4). 

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). 

By substituting alternately the carbon atoms in cubic diamond by zinc and sulfur atoms, one obtains the structure of zinc blende (sphalerite). By the corresponding substitution in hexagonal diamond, the wurtzite structure results. As long as atoms of one element are allowed to be bonded only to atoms of the other element, binary compounds can only have a 1 1 composition. For the four bonds per atom an average of four electrons per atom are needed this condition is fulfilled if the total number of valence electrons is four times the number of atoms. Possible element combinations and examples are given in Table 12.1. 

In theory, the III-V compound semiconductors and their alloys are made from a one to one proportion of elements of the III and V columns of the periodic table. Most of them crystallize in the sphalerite (zinc-blende ZnS) structure. This structure is very similar to that of diamond but in the III-V compounds, the two cfc sublattices are different the anion sublattice contains the group V atoms and the cation sublattice the group III atoms. An excess of one of the constituents in the melt or in the growing atmosphere can induce excess atoms of one type (group V for instance) to occupy sites of the opposite sublattice (cation sublattice). Such atoms are said to be in an antisite configuration. Other possibilities related with deviations from stoichiometry are the existence of vacancies (absence of atoms on atomic sites) on the sublattice of the less abundant constituent and/or of interstitial atoms of the most abundant one. 

Very few Zn isotope compositions have been produced on ores. Marechal (1998) (see also Marechal and Albarede 2000) analyzed a variety of Zn carbonates (smithsonite) and sulfides (sphalerite) from different localities in Europe. The maximum range of 8 Zn values is from -0.06 to +0.69%o with little apparent sulfide/carbonate fractionation (smithsonite may be up to 0.3%o heavier than associated sphalerite). Unpublished data (Table 1) from the Lyon group on sphalerite from the Cevennes, Southeastern France fall within this range and show that the 8 Zn values from a single mine such as Les Malines cluster within =4).2%o of each other. 

Table 1. 5 Zn (%o) values of sphalerite from the Cevermes area. Southeastern Franee.

Table 7.7 Corrosive electrochemistry parameters of sphalerite at different pH...

Figure 7.41 is the polarization curves of sphalerite-carbon combination electrode in different collector solution at natural pH. The corrosive electrochemistry parameters are listed in Table 7.8. These results show that xanthate and dithiocarbamate have distinctly different effects on sphalerite. The corrosive potential and current of sphalerite electrode are, respectively, 42 mV and 0.13 pA/cm at natural pH in the absence of collector, -7 mV and 0.01 pA/cm in the presence of xanthate, and 32 mV and 0.12 pA/cm in the presence of dithiocarbamate. The corrosive potential and current decrease sharply with xanthate as a collector, indicating that the electrode surface has been totally covered by the collector film from the electrode reaction. Xanthate has big inhibiting corrosive efficiency and stronger action on sphalerite. However, the corrosive potential and current of sphalerite electrode have small change with dithiocarbamate as a collector, indicating that DDTC exhibits a weak action on sphalerite. 

Table 10.10 Separation results of the mixtures of two minerals (1 1) among galena, sphalerite and pyrite by h controlled flotation (pH modified by lime, grinding time for 5 min, in Fe medium)...

The flotation separation of galena, sphalerite and pyrite in Fankou lead-zinc mine is very complicated because these three minerals are finely disseminated. The OPCF technology is also successfully applied to this plant to separate these three minerals. Here, pH is modified to 12 by lime and pulp potential is maintained as less than 170 mV. The mixture of xanthate and DDTC is used as a collector in flotation of galena. CUSO4 is used as a collector in the flotation of sphalerite. The principal flowsheet of OPCF for flotation separation of Fankou lead-zinc ore is given in Fig. 10.20. The comparison of results of plant production for OPCF and old flowsheet is listed in Table 10.16. It can be seen that the OPCF technique... 

Indium concentrations in the polymetallic veins show a wide range (3.4 to 1184ppm In, Table 1). Based on the correlation coefficients of ore geochemistry, significant Indium (up to 1184 ppm) is related to the Ps2 mineralization stage and closely associated with Fe-rich sphalerite, but also with ferrokesterite. There are important In anomalies in Psi (up to 159.4 ppm) that are related to the Sn minerals, cassiterite, ferrokesterite and stannite (Crespi 2006). 

For other minerals, such as pyrrhotite (and, in Table 4, an ideal composition of FeS is assumed, rather than the more realistic Fc 1 AS), galena or sphalerite, the following equations may apply ... 

Sn, and the sphalerite or the wurtzite arrangement (or both) by the compounds listed in Table 7-14. 

There are two polymorphic structures of ZnS, zinc blende (or sphalerite) (3 2PT) and wurtzite (2 2PT). In zinc blende there is a ccp arrangement of S atoms with Zn atoms filling one of the two T layers as shown in Figure 6.1. The diamond has the same structure, with the sites of P and one T layer filled by C atoms (Section 4.3.3). The structure of zinc blende has six (3 2) layers in the repeating unit. This structure is encountered for many binary compounds with significant covalent character as shown in Table 6.1. The space group for zinc blende is T%, F43m, and a0 = 5.4093 A, for the cubic unit cell. ... 

Results of the analyses on coals before and after treatment with aqueous Hd C03 solutions and molten NaOH/KOH mixtures at Ames Laboratory are shown in Table III. Levels of Cd, Pb and Zn were relatively high in the raw Illinois No. 6 run-of-mine coal used for the Na2C0, treatments. The elevated Cd levels correlate well with the high zn levels, since Cd in coal is commonly associated with sphalerite (ZnS). The Pb was probably present largely as galena (PbS). 

The triboluminescence of minerals has been studied visually (see the footnotes to Table I) but only a few minerals have been examined spectroscopically. There are a few clear examples of noncentric crystals, such as quartz, whose emission is lightning, sometimes with black body radiation. Most of the triboluminescent minerals appear to have activity and color which is dependent on impurities, as is the case for kunzite, fluorite, sphalerite and probably the alkali halides. Table I attempts to distinguish between fracto-luminescence and deformation luminescence, but the distinctions are not clear cut. A detailed analysis of the structural features of triboluminescent and nontriboluminescent minerals may make it possible to draw conclusions about the nature and concentration of trace impurities that are not obvious from the color or geological site of the crystals. Triboluminescence could be used as an additional method for characterizing minerals in the field, using only the standard rock hammer, with the sensitive human eye as a detector. 

Table 1-4 provides some data selected from El Shazly et al. (1956) for epigenetic sphalerite. The high concentrations of Cd should be noted. During smelting the ZnS is reduced to Zn metal and the Cd is then an impurity in the ingot metal. Subsequent... 

Table 1-4. Concentrations (pg g ) of guest trace elements in selected samples of epigenetic sphalerite. Data from El Shazly et al. (1956). ...

The c/a ratio also correlates with the differences of the electronegativities the compounds with the greatest differences show the largest departure from the ideal c/a ratio [3], The distortions were explained by long-range polar interactions. Only wurtzite structures with c/a ratios lower than the ideal value of 1.633 are stable (otherwise the sphalerite structure is a stable one). The structure parameters for the Ill-nitrides are given in TABLE 1. 

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