Pyrrhotite pyrite

Magnetite is common in Pb-Zn-Mn and Cu deposits but has not been reported in Au-Ag deposits. It commonly coexists with other iron minerals such as hematite, pyrite, pyrrhotite, siderite, and chlorite and also occurs in both the main stage of sulfide mineralization and in the late stage of mineralization. 

Yatani argentite electrum, chalcopyrite, marcasite, pyrite, pyrrhotite, galena, sphalerite quartz, adularia, chlorite, sericite, rhodochrosite... 

Iriki fahore, gold-fieldite, native tellurium fahore, famatinite argentite, chalcopyrite, fabore, famatinite, arsenopyrite, marcasitc, pyrite, pyrrhotite quartz, kaolinite, anatase... 

Opaque minerals include stibnite, jamesonite, cinnabar, gold, pyrite, pyrrhotite, arsenopyrite, marcasite, sphalerite, galena and chalcopyrite. 

Main opaque minerals include native gold, electrum, pyrite, pyrrhotite, chalcopy-rite, cubanite, sphalerite, arsenopyrite and tellurobismutite. The amounts of these sulfide minerals are poor, compared with those in epithermal Au-Ag vein-type deposits. It is noteworthy that silver minerals are abundant in epithermal Au-Ag vein-type deposits, whereas they are poor in gold-quartz veins. 

The veins are composed mostly of quartz and a small amount of sulfide minerals (pyrite, pyrrhotite, arsenopyrite, chalcopyrite, sphalerite, and galena), carbonate minerals (calcite, dolomite) and gold, and include breccias of the host rocks with carbonaceous matters. Layering by carbonaceous matters has been occasionally observed in the veins. Banding structure, wall rock alteration and an evidence of boiling of fluids that are commonly observed in epithermal veins have not been usually found. 

Wood, S.A., Crerar, D.A. and Borcsik, M.P. (1987) Solubility of the assemblage pyrite-pyrrhotite-magnetite-sphalerite-galena-gold-stibnite-bismuthinite-argentite-molybdenite in H20-NaCl-C02 solutions from 200°C to 350°C. Econ. Geol, 82, 1864-1887. 

The H2S concentration of hydrothermal solution is plotted in Fig. 2.33. Based on these data, we can estimate the temperature of hydrothermal solution buffered by alteration mineral assemblages such as anhydrite-pyrite-calcite-magnetite and pyrite-pyrrhotite-magnetite for Okinawa fluids. 

For example, assuming anhydrite-magnetite-calcite-pyrite-pyrrhotite buffers redox in sub-seafloor reaction zones and a pressure of 500 bars, dissolved H2Saq concentrations of 21 °N EPR fluid indicate a temperature of 370-385°C. However, the estimated temperatures are higher than those of the measurement. This difference could be explained by adiabatic ascension and probably conductive heat loss during ascension of hydrothermal solution from deeper parts where chemical compositions of hydrothermal solutions are buffered by these assemblages. 

Fig. 2.33. H2Saq concentration.s as a function of temperature for hot spring fluids at midocean ridges as a function of redox. Assuming AMPC (anhydrite-magnetite-pyrite-calcite) and PPM (pyrite-pyrrhotite) buffers redox in sub-seafloor reaction zones and a pressure of 500 bars, dissolved H2Saq concentrations indicate temperatures of approximately 370-385°C. Solid star Okinawa. (Modified after Seyfried and Ding, 1995.)...

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 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)...

Amplats - Mine 3 South Africa, Morensky Reef Grind To a K%0 of 87 pm Reagents CUSO4 = 100-200 g/t, dibutyl xanthate = 320 g/t. Modified guar gum = 200-250 g/t Metallurgy 90-100 g/t total PGM in concentrate, PGM recovery = 80-82% Ore Sulphide-dominated PGM deposit containing Cu/Ni and mixed pyrite-pyrrhotite. The main floatable gangues are calcite, chlorites with lesser talc... 

Depending on the composition of disseminated and medium-coarse-grained ore, they can be divided into two basic groups sulphides and chloritic tourmaline ores. In the sulphide ore, the minerals are represented by pyrite, pyrrhotite, arsenopyrite, chalcopyrite, galena and stannin. Less common are sphalerite and bismuth. 

The San Rafael tin mine is one of the richest ore mine in the world, with a head grade of about 5% Sn. The mine actually started in the 1960s as a copper operation, and later tin was discovered and the operation started as a tin operation. The ore is coarse grained, and a portion of the tin was recovered at a relatively coarse-grind size (i.e. 8 mm size). The main gangue minerals found in this ore were silicates, pyrite, pyrrhotite, tourmaline and minor amounts of copper and silver. 

Leppinen (1990) used FTIR-ATR techniques to study the adsorption of ethyl xanthate on pyrite, pyrrhotite and chalcopyrite. The FTIR spectra of the reaction products on pyrite, pyrrhotite and chalcopyrite after treatment with 1x10 mol/L KEX solution at pH = 5 is presented in Fig. 1.7. He found that the FTIR signals... 

In the case of mineral-mineral interactions, a mineral with higher potential acts as a cathode, while a mineral with lower potential acts as an anode. For a multiple mineral/grinding media(steel)system. The galvanic interactions become more complex than the two-electrode systems. The galvanic reactions among multielectrode systems are also governed by the mixed potential principle as shown in an example of polarization curves involving pyrite, pyrrhotite and mild steel in Fig. 1.9 (Pozzo and Iwasaki, 1987). 

Figure 1.9 Determination of corrosion currents for pyrite-mild steel (Py-MS) pyrrhotite-mild steel (Po-MS) and pyrite-pyrrhotite-mild steel (Py-Po-MS)systems under abrasion in a quartzite slurry by adjusting to the surface area ratios of ground minerals and steel balls (Pozzo and Iwasaki, 1987)...

Nakazawa and Iwasaki (1985) and Pozzo, Malicsi and Iwasaki (1988) investigated a pyrite-pyrrhotite contact and a pyrite-pyrrhotite-grinding media contact on flotation, respectively. They found that the floatability of pyrrhotite increased in the presence of pyrite, whereas it decreased in the presence of both pyrite and grinding media (mild steel). Similarly, a galvanic contact between nickel arsenide and pyrrhotite decreased the floatability of pyrrhotite (Nakazawa and Iwasaki, 1986). 

From the Eqs. (3-1) to (3-13), the h-pH diagram of sodium sulphide solution is constructed with element sulphxir as metastable phase considering the presence of barrier (about 300kJ/mol) or overpotential (about 3.114 mV) of sulphide oxidation to sulphate and shown in Fig. 3.7. It is obvious that the lower limit of potential of sodium sulphide-induced collectorless flotation of pyrite, pyrrhotite and arsenopyrite at various pH agree well with the potential defined respectively by reactions of Eq. (3-9) producing elemental sulphur. The initial potential... 

Figure 3.7 Electrochemical phase diagram for sodium sulphide with elemental sulphur as metastable phase. Equilibrium lines (solid lines) correspond to dissolved species at 10" mol/L. Plotted points show the upper and lower limit potential of sulphur-included flotation of pyrite, pyrrhotite and arsenopyrite from literature...

Pozzo, R. L., Malicsi, A. S., Iwasaki, L, 1988. Pyrite-pryyhotite-grinding media contact and its effect on flotation. Minerals Metallurgical Processing, 5(1) 16-21 Pozzo, R. L., Malicsi, A. S., Iwasaki, I., 1990. Pyrite-pyrrhotite-grinding media contact and its effect on flotation. Minerals Metallurgical Processing, 7(1) 16 - 21 Prestidge, C. A., Thiel, A. G., Ralston, J., Smart, R. S. C., 1994. The interaction of ethyl xanthate with copper (II)—activated zinc sulphide kinetic effects. Colloids Surfece, A. Physicochem. Eng. Aspects, 85 51 - 68... 

Uncertainties associated with T estimates based on equation 11.176 range from 20 to 25 K (pyrite-galena) to 40 to 55 K (pyrite-pyrrhotite). 

The pyrite-chalcopyrite-pyrrhotite assemblage contains up to 1% Cu, and consists of disseminated to massive pyrite, pyrrhotite, with subordinate remobilized chalcopyrite filling the intragranular fractures in pyrite and interstitial spaces between highly strained and brecciated Fe-sulfides (Saif 1983 Fig. 2). 

The most conventional catalytic material since the work of Bergius has been iron sulfide in various types. Pyrite, pyrrhotite, and various nonstoi-chiometric sulfides are known, and pyrrotite is postulated as the active form. Its precursors are red mud, residue of bauxite after the separation of alumina, iron ores of various sources, synthetic and natural pyrites, fine iron particles, iron dust from converters, iron sulfate, iron hydroxide, etc. (32, 33). 

The silicate facies is of a black finely laminated type, consisting mainly of magnetite with up to 15 vol. % grunerite and up to 5% carbonaceous matter. The facies is found in layers up to a few dm thick. Common to the silicate facies is the scarcity of quartz and the complete absence of carbonates. The sulphide facies of Isua consists of up to 60 vol. % sulphides (pyrite, pyrrhotite) together with grunerite or actinolite and magnetite (Appel, 1980) 118). 

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