The Leachate of Lead from the Crucibles Undergone Ruby Heat Treatment with Lead Glass Additive

AbstractHeat treatment with lead glass additive is developed to improve the quality of rubies. The alumina crucibles which were used as containers are not subjected to the hazardous waste laws. Therefore, this research constituted a study to characterize and determines lead contents in the leachate from these crucibles by two methods, the toxicity characteristic leaching procedure (TCLP) and synthetic precipitation leaching procedure (SPLP) as simulation of leaching conditions of landfill and acid rain, respectively. Discarded crucibles from 6 factories gives lead concentrations ranging from 0.58 to 335.73 (TCLP) and 0.35 to 312.17mg /l (SPLP), with a positive correlation between them. For the pH values, the leachates by TCLP seem to be constant at 5.00-5.17 while those by SPLP seem to be fluctuated, ranging from 6.64 to 9.73. The increasing in pH value doses not correspond with the increasing in lead concentration level

Mineralogical and Chemical Characteristics of Gossan Waste Rocks from a Gold Mine in Northeastern Thailand

The mineralogical and chemical compositions of various ocher gossans from a gold mine in northeastern Thailand were investigated, including some heavy metals and other toxic elements. Mineralogical characteristics were carried out using X-Ray Diffractometer (XRD) and Scanning Electron Microscope (SEM) whereas chemical compositions were analyzed using Electron Probe Micro-Analyzer (EPMA). These ocher gossans can be classified, initially based on Munsell color, into five types: type-I (pale-yellow color), type-II (brownish-yellow color), type-III (yellowish-brown color), type-IV (dusky-red color) and type-V (red color). The primary silicate minerals (i.e., quartz, garnet epidote and amphibole) are found in type -I, -II, -III and -IV. They appear to be composed of skarn rock. On the other hand, the secondary minerals (i.e., goethite, jarosite, ankerite, montmorillonite, magnetite, gypsum and secondary quartz) are observed in types-II, -III, -IV and    -V. As and Cu are found crucially in types-III, -IV and -V in which both elements can be adsorbed by goethite and/or jarosite. As the result, the gossan rocks in this area are natural adsorbents with high potential to reduce As and Cu contamination into the ecosystem. Therefore, the gossan, a natural attenuation material, is recommended for site remediation because of its low cost and local abundance. Feasibility studies should be conducted to further investigate the potential

Greenhouse Gases and Energy Intensity of Granite Rock Mining Operations in Thailand: A Case of Industrial Rock-Construction

This paper is aimed to systematically assess greenhouse gases (GHGs) and energy intensity of the granite rock mining operations in Thailand and also identify a range of feasible options to minimize their GHG emissions. Mining factories A, B and C, located in the Eastern region of Thailand, were selected as research case studies. The results indicated that the 3-year average of GHGs emissions from factories A to C was 3387 718 kgCO2e per year with approximately 2.92 kgCO2e per ton of granite rock produced over 2012 to 2014. Of this, the carbon intensity of grid-electricity consumption for the crushed rock production was 1.84 kgCO2/kWh. Diesel fuel combustion for transport activities in the mining factories was the greatest contributor to GHGs emissions (68 %) compared to the purchased electricity and explosion process, with 31 % and 1 %, respectively. In-Pit Crushing and Conveying (IPCC) installation, haul truck payload optimization and management, and reduction in tire rolling resistance have shown potential to reduce carbon emissions accounted for 20 % to 70 %

Cause of Color Modification in Tanzanite after Heat Treatment

Natural tanzanites usually show strongly trichroic coloration from violet to blue, and brown colors in different directions. However, this characteristic is easily changed to violet-blue dichroism after heat treatment. Moreover, the cause of color modification after heating is still controversial. A few researchers have previously suggested that trace amounts of either vanadium or titanium substituted in aluminum site should be the main determinant of color after the heat treatment. Alteration of either V3+ to V4+ or Ti3+ to Ti4+ may relate to light absorption around 450–460 nm, which is the main cause. UV/vis/NIR absorption spectroscopy and X-ray absorption spectroscopy (XAS), a utility of synchrotron radiation, were applied for this experiment. As a result, the violet-blue absorption band (centered around 450–460 nm) as well as green absorption band (centered around 520 nm) were obviously decreased along the c-axis after heating, and XAS analysis indicated the increasing of the oxidation state of vanadium. This result was well supported by the chemical composition of samples. Consequently, vanadium was strongly suggested as the significant coloring agent in tanzanite after heat treatment

Minor Elements and Color Causing Role in Spinel: Multi-Analytical Approaches

Natural spinel (MgAl2O4) usually contains some minor and trace elements (e.g., Cr, Co, Fe, V) that may cause various hues. The ratios of these chromophores directly affect the color composition. The red color in spinel is attributed to the combination of significant Cr and V. Magenta and purple to blue and green colors in spinels are affected by the significant Fe concentration, whereas orange color in spinel shows the contribution of significant V content compared to Cr and Fe. After the heating experiment, advanced gemological investigation reveals some noteworthy characteristic features. X-ray absorption spectroscopy (XAS) indicates a greater change in oxidation state, as well as disordering of Fe and V. Broadening of the dominant peak at around 406 cm−1 with occurrences of additional small peaks at around 715–719 cm−1 in Raman spectra, as well as broadening of the 685 nm (R-line) and poorly defined structure of additional peaks (N-lines) in photoluminescence spectra should be significant indicators of spinel undergone heat treatment

Variety of Iron Oxide Inclusions in Sapphire from Southern Vietnam: Indication of Environmental Change during Crystallization

Sapphires from alluvial deposits associated with Cenozoic basalts in Southern Vietnam were collected for investigation of mineral inclusions. In this report, primary iron oxide inclusions were focused on, with detailed mineral chemistry using a Raman spectroscope and electron probe micro-analyzer. Consequently, a variety of iron oxide inclusions were recognized as wüstite, hercynite, and ilmenite. Ilmenite falling within an ilmenite–hematite series ranged in composition between Il24-30He36-38Mt35-40 and Il49-54He34-40Mt7-10, classified as titanomagnetite and titanohematite, respectively. Wüstite with non-stoichiometry, (Fe2+0.3-0.9)(Ti3+Al3+≤0.6Cr3+Fe3+≤0.46)☐≤0.23O, was associated with hercynite inclusions, clearly indicating cogenetic sapphire formation. Wüstite and sapphire appear to have been formed from the breakdown reaction of hercynite (hercynite = sapphire+wüstite) within a reduction magma chamber. Titanohematite and titanomagnetite series might have crystallized during iron–titanium reequilibration via subsolidus exsolution under a slightly oxidized cooling process

Factors controlling the release of metals and a metalloid from the tailings of a gold mine in Thailand

Concentration of metals and As leached from the sulphide mixing and oxide zones at differing pH