Pyrite comparison

As shown in Fig. 1.7, sodium mercapto-benzothiazole performs strong collecting capability toward galena, but weak collecting capability toward pyrite. Comparison of sodium mercapto-benzothiazole and hulyl xanthate in the flotation of galena mineral is as follows ... 

Shikazono, N. (1985d) A comparison of temperatures estimated from the electrum-sphalerite-pyrite-argentite assemblage and filling temperatures of fluid inclusions from epithermal Au-Ag vein-type deposits in Japan. Econ. Geol, 80, 1415-1424. 

Table 7.1 Comparison of the yields of carbon-containing compounds obtained from an atmosphere of CH4, NH3, H2O and H2 using spark discharges with those obtained under hydrothermal conditions from a mixture of HCN, HCHO and NH3 at 423 K and 10 atm in the presence of pyrite-pyrrhotite-magnetite redox buffer (Holm and Andersson, 1995)...

Sulphides. The partially ionic alkali metal sulphides Me2S have the anti-fluorite-type structure (each Me surrounded by a tetrahedron of S, and each S atom surrounded by a cube of Me). The NaCl-structure type (6/6 coordination) is adopted by several mono-sulphides (alkaline earth, rare earth metals), whereas for instance the cubic ZnS-type structure (coordination 4/4) is observed in BeS, ZnS, CdS, HgS, etc. The hexagonal NiAs-type structure, the characteristics of which are described in 7.4.2.4.2, is observed in several mono-sulphides (and mono-selenides and tellurides) of the first-row transition metals the related Cdl2 (NiAs defect-derivative) type is formed by various di-chalcogenides. Pyrite (cP 12-FeS2 type see in 7.4.3.13 its description, and a comparison with the NaCl type) and marcasite oP6-FeS2 are structural types frequently observed in several sulphides containing the S2 unit. 

Figure 1.4 Comparison of UV spectrum of cyclohexane extract of sulphidized pyrite after flotation with that of cyclohexane solution of sulphur (Heyes and Trahar, 1984)...

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... 

Compositional variations among all textural types are obvious (Fig. 1) and a comparison of type 1 pyrite in proximal and distal locations is shown in Fig. 2 (Note that data have not been included for elements where a large proportion [>40%] of results were below detection limit). 

Figure 1. Comparison of FTIR and ASTM Results for Pyrite, wt % of LTA (Solid Line - Parity, Dotted Line - Least-Squares y -0.985 X + 0.098).

Oxidation of Reduced S. Indirect evidence suggests that microbial oxidation of sulfide is important in sediments. If it is assumed that loss of organic S from sediments occurs via formation of H2S and subsequent oxidation of sulfide to sulfate (with the exception of pyrite, no intermediate oxidation states accumulate in sediments cf. 120, 121), the stated estimates of organic S mineralization suggest that sulfide production and oxidation rates of 3.6-124 mmol/m2 per year occur in lake sediments. Similar estimates were made by Cook and Schindler (1.5 mmol/m2 per year 122) and Nriagu (11 mmol/m2 per year 25). A comparison of sulfate reduction rates (Table I) and rates of reduced S accumulation in sediments (Table III) indicates that most sulfide produced by sulfate reduction also must be reoxidized but at rates of 716-8700 mmol/m2 per year. Comparison of abiotic and microbial oxidation rates suggests that such high rates of sulfide oxidation are possible only via microbial mediation. 

Figure 4. Comparison of isotopic composition of pyritic and organic sulfur in low- and high-sulfur coals in the Illinois Basin. Data are taken form Westgate and Anderson (113). Samples were collected from the top, middle, and base of the Herrin Coal at each mine.

Analytical values for the eight coals after treatment with 2 M HN03 are given in Table III. The reported values are the averages of four determinations (duplicate determinations on different days). A comparison of the dry ash values for the HNOj-extracted residues described in Table III to the dry ash values for the raw coals described in Table I reflects the reduction in mineral matter caused by extraction of the raw coals with 2 M HN03. Carbonates, sulfates, and other minerals dissolve in the acid solution used to extract pyrite. 

Figure 5. Comparison of ion intensities with and without bulk pyrite for selected species.

Figure 2. Comparison of ethyl and methyl alcohols as supercritical desulfurization fluids, for coals of varied organic sulfur/ pyritic sulfur ratio, (ethanol -------, methanol — —)...

Figure 6.2. Comparison of rate constants as a function of pH for reaction 4, oxidati on of pyrite by Fe3+ reaction 2, oxidation of Fe2+by 02 and reaction 1, oxidation of pyrite by 02. Reactions 1, 2, and 4 are given in the text as reactions 6.1, 6.2, and 6.4, respectively (from Nordstrom, 1982, with permission).

Thus, sulfide levels in interstitial waters increase. A number of elements form insoluble sulfides, which under these anoxic conditions are precipitated and retained within the sediments. A notable example is the accumulation of pyrite, FeS2, but also Ag, Cu, Pb and Zn are enriched in anoxic sediments in comparison with oxic ones. 

The characteristic structure parameters of the pyrite structure, as obtained by the DFT calculations, are given in Tab.l in comparison to the experimental values. For the measured lattice parameters a, FeS2 has a minimum. The position parameters increase... 

I have not come across Black Pyrites myself, and so have been unable to test the above statement. Possibly Pliny is referring to Black Cobalt, which possesses the quality in question. Solinus corroborates Pliny, who also terms Coral Pyrites, because fire can be derived from it. On the same ground he institutes a comparison with Chalcedony and common Flint, while others identify our Cuprine Slate with Pyrites. This Stone is very susceptible to impressions when under the earth. Sometimes it has representations of fishes, serpents, and tree-crickets sometimes an elaborate picture of a cock with drooping feathers and double comb. 

Raiswell R., Canfield D. E., and Berner R. A. (1994) A comparison of iron extraction methods for the determination of the degree of pyritization and the recognition of iron-limited pyrite formation. Chem. Geol. Ill, 101-110. 

Figure 4 Sulfur isotope summary for black shales from the Pierre Shale of the Cretaceous Western Interior, North America (Gautier, 1986, 1987), and the Jurassic Posidonienschiefer and Jet Rock (Raiswell et al., 1993). For comparison, the maximum fractionation observed in the Posidonienschiefer by Fisher and Hudson (1987) is also shown. The isotopically uniform and strongly S-depleted pyrites of the Jurassic shales and the Cretaceous Sharon Springs Member of the Pierre Shale—like the sediments of the modern Black Sea and Cariaco Basin (Figure 7)—are diagnostic of euxinic (water-column) pyrite formation (see Section 7.06.3.4.2). By contrast, the Cretaceous Gammon Shale shows the S enrichments and broad range of 6 S values possible under oxic depositional conditions (Gautier, 1986, 1987).

Leventhal J. and Taylor C. (1990) Comparison of methods to determine degree of pyritization. Geochim. Cosmochim. 

Olson G. J. (1991) Rate of pyrite bioleaching by Thiobacillus ferrooxidans-rcsults of an interlaboratory comparison. Appl. Environ. Microbiol. 57, 642-644. 

Table VI. Comparison of Ferric Sulfate and Chloride for Pyrite...

---