A geochemical modeling of gold deposition was performed using the EQ3/EQ6 software package using conditions inferred from geological, petrographic, geochemical and fluid inclusion data from the Bloco do Butiá gold mine, Lavras do Sul, RS. Gold in the mine occurs only in the pyrite structure (invisible gold). The pyrite occurs associated with white mica (phengite) in the zone of phyllic alterati...

Ultrasonic vibration gas-solid fluidized bed was proposed and introduced to separate fine coals (0.5-0.125 mm fraction). Several technological methods such as XRF, XRD, XPS, and EPMA were used to study the composition of heavy products to evaluate the separation effect. Results show that the ultrasonic vibration force field strengthens the particle separation process based on density when the v...

Biofilm formation and the production of extracellular polymeric substances (EPS) by meso- and thermoacidophilic metal-oxidizing archaea on relevant substrates have been studied to a limited extent. In order to investigate glycoconjugates, a major part of the EPS, during biofilm formation/bioleaching by archaea on pyrite, a screening with 75 commercially available lectins by fluorescence lectin-...

The Devonian massive sulfide orebodies of the West Shasta district in northern California are composed primarily of pyrite, with lesser amounts of other sulfide and gangue minerals. Examination of polished thin sections of more than 100 samples from the Mammoth, Shasta King, Early Bird, Balaklala, Keystone, and Iron Mountain mines suggests that mineralization may be divided into six paragenetic...

[1] The discovery of sulfate-rich layered deposits with hematite spherules at the landing site of the Opportunity rover is consistent with mineral deposition in an aqueous environment. We evaluate conditions responsible for the formation of a jarosite-goethite-gypsum assemblage with speciation calculations. The results show that the assemblage could have precipitated from acidic solutions forme...

In spite of the environmental and commercial interests in the bacterial leaching of pyrite, two central questions have not been answered after more than 35 years of research: does Thiobacillus ferrooxidans enhance the rate of leaching above that achieved by ferric sulfate solutions under the same conditions, and if so, how do the bacteria affect such an enhancement? Experimental conditions of p...

Dynamic transformations of iron occur seasonally at Great Sippewissett Marsh, Massachusetts. Small changes in the dissolved iron concentration in porewater represent only a small fraction of the iron involved in transformation reactions during the year. During the growing season, salt marsh grasses oxidize the sediment, and a large percentage of sedimentary pyrite is converted to an oxidized ir...

Oxidation of pyrite in aqueous solutions in contact with air (oxygen 20%) was studied at 25°C using short-term batch experiments. Fe and SO4 2 were the only dissolved Fe and S species detected in these solutions. After a short period, R [S]tot/[Fe]tot stabilized from 1.25 at pH 1.5 to 1.6 at pH 3. These R values were found to be consistent with previously published measurements (as calculated f...

Arsenic (As) is being released from the Suwannee Limestone, Upper Floridan aquifer, during aquifer storage and recovery (ASR) cycle testing with concentrations of up to 130 μg/L in the recovered water. To determine the abundance and mineralogical association of As in the Suwannee Limestone matrix we have conducted a detailed mineralogical and geochemical study of 306 core samples. In addition t...