Environmental geochemistry of the derelict Webbs Consols mine,New South Wales,Australia

Small-scale mining and mineral processing at the Webbs Consols polymetallic PbZnAg deposit in northern New South Wales, Australia has caused a significant environmental impact on streams, soils and vegetation. Unconfined waste rock dumps and tailings dams are the source of the problems. The partly oxidised sulphidic mine wastes contain abundant sulphides (arsenopyrite, sphalerite, galena) and oxidation products (scorodite, anglesite, smectite, Fe-oxyhydroxides), and possess extreme As and Pb (wt% levels) and elevated Ag, Cd, Cu, Sb and Zn values. Contemporary sulphide oxidation, hardpan formation, crystallisation of mineral efflorescences and acid mine drainage generation occur within the waste repositories. Acid seepages (pH 1.9–6.0) from waste dumps, tailings dams and mine workings display extreme As, Pb and Zn and elevated Cd, Cu and Sb contents. Drainage from the area is by the strongly contaminated Webbs Consols Creek and although this stream joins and is diluted by the much larger Severn River, contamination of water and stream sediments in the latter is evident for 1–5 km, and 12 km respectively, downstream of the mine site. The pronounced contamination of local and regional soils and sediments, despite the relatively small scale of the former operation, is due to the high metal tenor of abandoned waste material and the scarcity of neutralising minerals. Any rehabilitation plan of the site should include the relocation of waste materials to higher ground and capping, with only partial neutralisation of the waste to pH 4–5 in order to limit potential dissolution of scorodite and mobilisation of As into seepages and stream waters.     

Remobilization of arsenic from buried wastes at an industrial site: mineralogical and geochemical control

An industrial area contaminated by As was studied to determine the source of this element and its speciation in As-bearing solids and in run-off waters. Mineral precipitates and water samples were collected and analyzed to assess processes controlling As mobility at this site. The integrated study of a contaminated industrial area allowed identification of the source of the As and of the nature of secondary As-bearing phases. The results obtained both on solid and water samples were used to model As behavior during waste leaching on carbonate rocks. At the upper end of a topographic transect across the site, run-off waters (pH=7.9) interact with surficial waste piles (containing arsenolite, arsenopyrite and pyrite), becoming acidic (pH=2.2) and concentrated in dissolved arsenate species (As⁵⁺) (ΣAs ranging from 0.961 to 3.149·10⁻³ mol/l). Those acidic waters interact with the limestone substratum, providing dissolved Ca which reacts with As to precipitate 1:1 Ca arsenates (weilite CaHAsO₄, haidingerite CaHAsO₄.H₂O and pharmacolite CaHAsO₄.2H₂O) and, in minor amounts, Ca–Mg arsenates (picropharmacolite (Ca,Mg)₃(AsO₄)₂ 6H₂O). The 1:1 Ca arsenates identified are known to precipitate at low pH (3–6) and seem to be stable in media with high dissolved CO₂, in comparison with other types of Ca arsenates. However, due to their high solubilities, they are not strictly relevant candidates to immobilize As in contaminated surficial environments. Although reported solubilities decrease to values close to the French and US drinking standards in Ca-rich solutions, a thorough examination of the precipitation/dissolution kinetics of Ca arsenates should be undertaken to assess their long-term stability and their efficiency in rapidly immobilizing As in contaminated surficial environments.     

Hanford tank residual waste – Contaminant source terms and release models

Residual waste is expected to be left in 177 underground storage tanks after closure at the US Department of Energy’s Hanford Site in Washington State, USA. In the long term, the residual wastes may represent a potential source of contamination to the subsurface environment. Residual materials that cannot be completely removed during the tank closure process are being studied to identify and characterize the solid phases and estimate the release of contaminants from these solids to water that might enter the closed tanks in the future. As of the end of 2009, residual waste from five tanks has been evaluated. Residual wastes from adjacent tanks C-202 and C-203 have high U concentrations of 24 and 59 wt.%, respectively, while residual wastes from nearby tanks C-103 and C-106 have low U concentrations of 0.4 and 0.03 wt.%, respectively. Aluminum concentrations are high (8.2–29.1 wt.%) in some tanks (C-103, C-106, and S-112) and relatively low (<1.5 wt.%) in other tanks (C-202 and C-203). Gibbsite is a common mineral in tanks with high Al concentrations, while non-crystalline U–Na–C–O–P ± H phases are common in the U-rich residual wastes from tanks C-202 and C-203. Iron oxides/hydroxides have been identified in all residual waste samples studied to date. Contaminant release from the residual wastes was studied by conducting batch leach tests using distilled deionized water, a Ca(OH)₂-saturated solution, or a CaCO₃-saturated water. Uranium release concentrations are highly dependent on waste and leachant compositions with dissolved U concentrations one or two orders of magnitude higher in the tests with high U residual wastes, and also higher when leached with the CaCO₃-saturated solution than with the Ca(OH)₂-saturated solution. Technetium leachability is not as strongly dependent on the concentration of Tc in the waste, and it appears to be slightly more leachable by the Ca(OH)₂-saturated solution than by the CaCO₃-saturated solution. In general, Tc is much less leachable (<10 wt.% of the available mass in the waste) than previously predicted. This may be due to the coprecipitation of trace concentrations of Tc in relatively insoluble phases such as Fe oxide/hydroxide solids.     

Chemical partitioning of trace and major elements in soils contaminated by mining and smelting activities

Soils from historical Pb mining and smelting areas in Derbyshire, England have been analysed by a 5-step sequential extraction procedure, with multielement determination on extraction solutions at each step by ICP-AES. Each of the chemical fractions is operationally defined as: (i) exchangeable; (ii) bound to carbonates or specifically adsorbed; (iii) bound to Fe–Mn oxides; (iv) bound to organic matter and sulphides; (v) residual. The precision was estimated to be about 5%, and the overall recovery rates were between 85 and 110%. The carbonate/specifically adsorbed and Fe–Mn oxide phases are the largest fractions for Pb in soils contaminated by both mining and smelting. Most of the Zn is associated with Fe–Mn oxide and the residual fractions. Cadmium is concentrated in the first 3 extraction steps, particularly in the exchangeable phase. The most marked difference found between soils from the mining and smelting sites is the much higher concentrations and proportions of metals in the exchangeable fraction at the latter sites. This indicates greater mobility and potential bioavailability of Pb, Zn and Cd in soils at the smelting sites than in those in the mining area. The most important fraction for Fe and Al is the residual phase, followed by the Fe–Mn oxide forms. In contrast, the Fe–Mn oxide fraction is the dominant phase for Mn in these soils. In the mining area, most of the Ca is in the carbonate fraction (CaCO₃), while the exchangeable and residual phases are the main fractions for Ca at the smelting sites. Phosphorus is mainly in the residual and organic fractions in both areas. The exchangeable fractions of Pb, Zn and Cd in soils were found to be significantly related to the concentrations of these metals in pasture herbage.     

Quantitative X-Ray Diffraction Technique for Evaluating the Stabilization of Hazardous Metals in Ceramic Products

A sustainable waste management system requires the beneficial uses of waste residues, such as sludge and incineration ashes, generated from environmental treatments. Among the use strategies, the practices of mixing hazardous metal-bearing solids with clay materials to produce ceramic products are often found with significant improvement in reducing the metal leach ability from products. However, relatively much fewer studies have clearly answered the questions of "What are the metal stabilization mechanisms other than simply the dilution effect and the encapsulation of metals?"; "What are the mineral phases of metals and how much are they in the products?"; and "How thermal conditions can effetely promote the transformations of metal-hosting mineral phases?". As many sustainability movements have increasingly promoted the adoption of those products generated from the beneficial use of waste materials, quantitative understandings of the metal incorporation efficiencies are important to facilitate the design of safe and reliable waste-to-resource strategies. Current findings on the metal incorporation mechanisms between common alumino silicates and hazardous metals (nickel, copper, and zinc) under different thermal conditions will be presented, and the results show the important role of forming aluminates and ferrites to significantly reduce the metal leach ability from the products. In the study, the technique of quantitative X-ray diffraction (QXRD) was applied to report the metal incorporation efficiencies through a 3-hour sintering process, aiming to stabilize the hazardous metals and also to turn the waste residues for usable ceramic products. Prolonged leach tests for potential metal-containing phases were carried out in acidic environments to evaluate the durability of thermally treated products. Both aluminate and ferrite spinels proved superior for thermomobilization of hazardous metals. With the information reported, this study has identified the key mechanisms of stabilizing the hazardous metals when thermally treated with common ceramic raw materials, and also demonstrates the importance of quantitative understanding in the development of a safe waste-to-resource strategy.     

Overheated, Cu-bearing magmas in the Zaldívar porphyry-Cu deposit, Northern Chile. Geodynamic consequences

The Zaldívar porphyry copper deposit, Northern Chile, consists of two major intrusions, the 290 Ma Zaldívar, and the more recent Miocene (38.7 Ma) Llamo porphyry. Five types of inclusions have been identified in quartz phenocrysts from Llamo porphyry, including melt inclusions (M), and four types of fluid inclusions, called MS (multi solids), B (brines), G (vapor-rich) and W (aqueous), respectively.Melt remnants, well preserved as M-inclusions, homogenize around 1000 °C. They show a rhyolitic composition, comparable to the most evolved acidic rhyolitic end member found elsewhere in the regional magmatism and to worldwide volcanic rhyolitic glass. High silica content in some inclusions can, however, be due to partial remelting of the quartz host during the heating run. Copper content in the same inclusions ranges between 0.03 and 0.57 wt.%, with an average concentration of 0.10 wt.%, suggesting a major magmatic source for the copper (orthomagmatic model).MS inclusions, which contain a number of solids at room temperature, mostly H₂O-bearing phases (system NaCl–KCl–((Fe, Mg, Cu)Cl)–H₂O, average salinity 70 wt.% NaCl equiv.), homogenize at magmatic temperatures (around 1000 °C). They represent the first fluids to have exsolved from the magma at depth, at a pressure of about 2 kbar. Their high homogenization temperature, comparable to values measured for melt inclusions (1000 to 1050 °C), may indicate trapping of MS and M inclusions in host phenocrysts from an immiscible mixture of silicate melt and highly saline fluids expelled from the magma during the early stage of quartz crystallization.The data indicate a magmatic origin for copper, as well as extremely high melt temperatures. These features are interpreted by magmatic differentiation of mantle-derived primitive melts, corresponding to major changes in the tectonic regime of the Andean margin, which occurred in Miocene times.     

Geological and anthropogenic factors influencing mercury speciation in mine wastes: an EXAFS spectroscopy study

The speciation of Hg is a critical determinant of its mobility, reactivity, and potential bioavailability in mine-impacted regions. Furthermore, Hg speciation in these complex natural systems is influenced by a number of physical, geological, and anthropogenic variables. In order to investigate the degree to which several of these variables may affect Hg speciation, extended X-ray absorption fine structure (EXAFS) spectroscopy was used to determine the Hg phases and relative proportions of these phases present in Hg-bearing wastes from selected mine-impacted regions in California and Nevada. The geological origin of Hg ore has a significant effect on Hg speciation in mine wastes. Specifically, samples collected from hot-spring Hg deposits were found to contain soluble Hg-chloride phases, while such phases were largely absent in samples from silica-carbonate Hg deposits; in both deposit types, however, Hg-sulfides in the form of cinnabar (HgS, hex.) and metacinnabar (HgS, cub.) dominate. Calcined wastes in which Hg ore was crushed and roasted in excess of 600 °C, contain high proportions of metacinnabar while the main Hg-containing phase in unroasted waste rock samples from the same mines is cinnabar. The calcining process is thought to promote the reconstructive phase transformation of cinnabar to metacinnabar, which typically occurs at 345 °C. The total Hg concentration in calcines is strongly correlated with particle size, with increases of nearly an order of magnitude in total Hg concentration between the 500–2000 μm and <45 μm size fractions (e.g., from 97–810 mg/kg Hg in calcines from the Sulphur Bank Mine, CA). The proportion of Hg-sulfides present also increased by 8–18% as particle size decreased over the same size range. This finding suggests that insoluble yet soft Hg-sulfides are subject to preferential mechanical weathering and become enriched in the fine-grained fraction, while soluble Hg phases are leached out more readily as particle size decreases. The speciation of Hg in mine wastes is similar to that in distributed sediments located downstream from the same waste piles, indicating that the transport of Hg from mine waste piles does not significantly impact Hg speciation. Hg L_III-EXAFS analysis of samples from Au mining regions, where elemental Hg(0) was introduced to aid in the Au recovery process, identified the presence of Hg-sulfides and schuetteite (Hg₃O₂SO₄), which may have formed as a result of long-term Hg(0) burial in reducing high-sulfide sediments.     

Recent advances in the geology of Koffiefontein Mine, Free State Province, South Africa

The complex internal geology of the Koffiefontein pipe has contributed to the marginal nature of the mine. The key to this is the presence of a large zone dominated by down-rafted country rock Karoo sediment and dolerite xenoliths. Recent work indicates that the kimberlite pipe at Koffiefontein consists of precursor dykes (the West and East Fissures), and the main pipe, in which two main eruptive phases have been recognized. Groundmass spinel compositions have been used to provide a chemical fingerprint of each lithology. There is evidence for at least three magma batches, each with its own chemical signature. Cross-cutting contact relationships were used to determine the emplacement sequence. The characterization of the different internal geological units permitted the development of a three-dimensional (3D) model of the pipe. Both main eruptive phases, viz., the Speckled west kimberlite and the Speckled east kimberlite comprise volcaniclastic kimberlite. They are separated by a large irregular mass of kimberlite that contains abundant country rock xenoliths comprising varying proportions of Karoo mudstone and dolerite, as well as probable bedded crater–facies fragments. This zone of contamination dilutes the grade of the kimberlites, affects the geotechnical stability and adversely affects the economics of the mine.     

The passivation of calcite by acid mine water. Column experiments with ferric sulfate and ferric chloride solutions at pH 2

Column experiments, simulating the behavior of passive treatment systems for acid mine drainage, have been performed. Acid solutions (HCl or H₂SO₄, pH 2), with initial concentrations of Fe(III) ranging from 250 to 1500 mg L⁻¹, were injected into column reactors packed with calcite grains at a constant flow rate. The composition of the solutions was monitored during the experiments. At the end of the experiments (passivation of the columns), the composition and structure of the solids were measured. The dissolution of calcite in the columns caused an increase in pH and the release of Ca into the solution, leading to the precipitation of gypsum and Fe–oxyhydroxysulfates (Fe(III)–SO₄–H⁺ solutions) or Fe–oxyhydroxychlorides (Fe(III)–Cl–H⁺ solutions). The columns worked as an efficient barrier for some time, increasing the pH of the circulating solutions from 2 to 6–7 and removing its metal content. However, after some time (several weeks, depending on the conditions), the columns became chemically inert. The results showed that passivation time increased with decreasing anion and metal content of the solutions. Gypsum was the phase responsible for the passivation of calcite in the experiments with Fe(III)–SO₄–H⁺ solutions. Schwertmannite and goethite appeared as the Fe(III) secondary phases in those experiments. Akaganeite was the phase responsible for the passivation of the system in the experiments with Fe(III)–Cl–H⁺ solutions.     

Sedimentary signatures of cyclic growth and destruction of stratovolcanoes: A case study from Mt. Taranaki, New Zealand

The long-term behaviour of andesite stratovolcanoes is characterised by a repetition of edifice growth phases followed by collapse. This cyclic pattern represents a natural frequency at varying timescales in the growth dynamics of stratovolcanoes worldwide. Around the > 130 ka Mt. Taranaki (Egmont volcano), New Zealand, coastal–cliff successions at 20–40 km distance comprise repeating packages of lithologically and sedimentologically distinctive mass-flow deposits. Varying depositional mechanisms and source properties of these units record growth and collapse cycles of the central edifice. These are used to construct a model for cyclic volcaniclastic sedimentation in the surrounds of stratovolcanoes. During edifice-construction phases, thick packages of tabular, predominantly monolithologic, hyperconcentrated-flow and debris-flow deposits accumulate with intercalated tephra beds. The mass-flow units commonly contain large proportions of fresh pumice or juvenile-lithic andesite. Intervals of quiescence separating eruptive periods are characterised by landscape re-adjustment, accompanied by deposition of fluvial and aeolian sediments, along with steady accretion of medial ash. In contrast, brief episodes of destruction are marked by wide-spread, distinctively clay-rich, polylithologic debris-avalanche deposits and related marginal debris flow units. The growth stages can be terminated by an eruption-triggered sector collapse, or by external forces once the edifice exceeds a critical stable height or profile (dependent on eruptive style and local geo-tectonic conditions). Once the edifice becomes metastable, regional tectonic earthquakes or shallow-level intrusion events are likely triggers for collapse. Although the resulting debris avalanches represent the greatest individual hazard from such andesite stratovolcanoes, their frequency is relatively low compared with other types of mass-flows generated during edifice-growth phases. Accurate forecasts of future hazard from mass-flow events are therefore dependent on recognition of both the frequency of a stratovolcano's growth cycle and its current position in that cycle.     

Chemometric Analysis of Mid-Wave Infrared Spectral Reflectance Data for Sulphide Ore Discrimination

Despite significant recent advancements in the sensor technologies, the use of sensors for raw material characterization in the mining industry remains limited. The aim of the present study was to assess the utility of applying the mid-wave infrared (MWIR) reflectance data acquired by the use of a handheld Fourier-transform infrared spectrometer (FTIR), combined with partial least squares-discriminant analysis (PLS-DA), for the characterization of a polymetallic sulphide ore deposit. In achieving the study objectives, focus was given to the MWIR portion of the FTIR dataset, as it is the least explored region of the infrared spectrum in mineral characterization studies. Three datasets—covering different wavelength ranges—were generated from the FTIR spectral data, namely the full FTIR range (2.5–15 µm), MWIR (2.5–7 µm) and long-wave infrared (LWIR: 7–15 µm), in order to investigate the associated information level of each defined wavelength region separately. Design of experiment was developed to determine the optimal data filtering techniques. Using the processed data and PLS-DA, a series of calibration and prediction models were developed for ore and waste materials separately. As the models applied to the MWIR data showed a successful classification rate of 86.3% for sulphide ore–waste discrimination, similarly using the full spectral FTIR dataset, a correct classification rate of 89.5% was achieved. This indicates that MWIR spectral range includes informative signals that are sufficient for classifying the material into ore or waste. The proposed approach could be extended for automating the sulphide ore–waste discrimination process, thus greatly benefiting marginally economical mining operations.

     

Anthropogenic metal loads and their sources in stream sediments of the Me?a River catchment area (NE Slovenia)

The Me?a River Valley has been a center of mining, ore processing and iron- and steel-based metallurgical industry for more than 300 a. This paper deals with stream sediments draining this area. Loads of potentially toxic metals and metal-bearing phases were investigated 10 a after the cessation of Pb and Zn mining. Sediments in the upper Me?a River Valley show significant pollution with Pb and Zn as a consequence of mining and ore processing. The highest contents of Pb and Zn were found in the Me?a tributaries, which directly drain mine waste deposits (maximum values: 19,300 mg/kg Pb and 37,900 mg/kg Zn). These results reflect transport of contaminated material from mine waste sites and indicate that the inactive mine and its mine wastes are sources of metal contamination in the surrounding environment. Contents of Cr, Ni, Cu and Co are increased in the lower Me?a River Valley, in the area of Ravne, as a result of the iron and steel industry. The contribution of the Me?a River to the metal-load in the Drava River is evident.Metal-bearing phases, identified in stream sediments by SEM/EDS, are assigned to three areas, according to their source and genesis. The Me?ica mining district source area is characterized by ore minerals of geogenic/technogenic origin (cerussite, sphalerite, smithsonite and galena), the Ravne source area is characterized by technogenic trace metal-bearing Fe-alloys, Fe-oxides and spherical trace metal-oxides and the Me?a and Drava River catchment areas are represented by geogenic metal-bearing accessory and common rock-forming minerals, such as zircon, ilmenite, rutile, sphene, barite and monazite. SEM/EDS analyses of stream sediments agree well with the results of chemical analyses and they prove to be a very useful tool for identification of metal-bearing phases and their characterization according to source and genesis.     

Crystallization of Cr-poor and Cr-rich megacryst suites from the host kimberlite magma: implications for mantle structure and the generation of kimberlite magmas

Cr-poor and Cr-rich megacryst suites, both comprising of varying proportions of megacrysts of orthopyroxene, clinopyroxene, garnet, olivine, ilmenite and a number of subordinate phases, coexist in many kimberlites, with wide geographic distribution. In rare instances, the two suites occur together on the scale of individual megacryst hand specimens. Deformation textures are common to both suites, suggesting an origin related to the formation of the sheared peridotites that also occur in kimberlites. Textures and compositions of the latter are interpreted to reflect deformation and metasomatism within the thermal aureole surrounding the kimberlite magma in the mantle. The megacrysts crystallized in this thermal aureole in pegmatitic veins representing small volumes of liquids derived from the host kimberlite magma, which were injected into a surrounding fracture network prior to kimberlite eruption. Close similarities between compositions of Cr-rich megacryst phases and those in granular lherzolites are consistent with early crystallization from a primitive kimberlite liquid. The low-Cr megacryst suite subsequently crystallized from residual Cr-depleted liquids. However, the Cr-poor suite also reflects the imprint of contamination by liquids formed by melting of inhomogeneously distributed mantle phases with low melting temperatures, such as calcite and phlogopite, present within the thermal aureole surrounding the kimberlite magma reservoir. Such carbonate-rich melts migrated into, and mixed with some, but not all, of the kimberlite liquids injected into the mantle fracture network. Contamination by the carbonate-rich melts changed the Ca–Mg and Mg–Fe crystal–liquid distribution coefficient, resulting in the crystallization of relatively Fe-rich and Ca-poor phases. The implied higher crystal-melt Mg–Fe distribution coefficient for carbonate-rich magmas accounts for the generation of small volumes of Mg-rich liquids that are highly enriched in incompatible elements (i.e. primary kimberlite magmas). The inferred metasomatic origin for the sheared peridotites implies that this suite provides little or no information regarding vertical changes in the thermal, chemical and mechanical characteristics of the mantle.     

Geostatistical estimation of multi-phase structures

A method is proposed for the characterization of the disjoint shapes of a multi-phase set. The method uses a global structural function and provides estimates of the complete mosaic of phases, honoring the individual volume proportions inferred from the experimental samples. The estimates of shapes can be improved by local conditioning to the covariance of each phase and to geometrical characteristics such as spatial orientation of the different strata. The mapping of uncertainty zones for individual phases is one advantage of using a geostatistical approach to characterize the morphology of qualitative (non-numerical) variables.     

Water leaching of cesium from selected cesium mineral analogues

Recently, a new mica phase Cs-tetra-ferri-annite has been synthesized and studied. This phase has been investigated because its high structural stability and assumed associated low leachability for Cs suggest that it may be a suitable waste form for immobilization of Cs. Further, synthesis, under hydrothermal conditions, is possible under conditions typical of an industrial-scale immobilization plant. Consequently, cesium-tetra-ferri-annite can be considered as a waste form for the fixation of Cs from solid radioactive waste. In this study, Cs immobilization in Cs-tetra-ferri-annite and CsAlSiO₄, as well as sorption onto montmorillonite and zeolite 13X, have been studied. Experiments were carried out to determine the influence of pH, temperature, time and leaching technique on the extent of release of Cs from these solids. These leaching studies have confirmed the limited leachability of Cs-tetra-ferri-annite, which was found to be more stable than CsAlSiO₄ by a factor of 3.7 at ambient temperature and near-neutral pH. These waste forms have also been found to be more effective in retaining Cs than Cs-montmorillonite and Cs-zeolite 13X. The relative release of Cs from all of the studied phases exhibits a similar trend with pH, temperature, time and techniques of leaching used in this study. For these phases, the leachability of Cs increases with acidity (pH 3) or alkalinity (pH 11) of the leachates as well as with increasing temperature and time of leaching. For CsAlSiO₄, the Cs-leachability was most strongly affected by increasing temperature. Cesium releases from this phase increased by a factor of about 6 when the temperature was raised from 20 to 100 °C. This increase with temperature was 3–6 times higher than that measured for the other phases. Under the present leaching conditions, Cs is released more than the matrix elements. Elements present in tetrahedral positions of CsAlSiO₄, Cs-montmorillonite and Cs-zeolite 13X leach much easier than elements in octahedral positions.     

Vitreous state in nature—Origin and properties

Vitreous materials are quite routinely found in natural settings. Most of them are aluminosilicates, which often occur in large deposits. Considering the geological formations in which naturally occurring vitreous aluminosilicates are found, they have generally remained stable for more than 1 Ma on the earth's surface, even in different geological and climatic environments. These non-crystalline solids played a very important role in the development of ancient human civilizations, long before the introduction of metallic tools. Today, however, the properties of natural glasses are of interest to mankind for completely different reasons. For example, industrial glasses are used today for encapsulating toxic wastes, especially radioactive waste, which remains active for centuries or more, in order to prevent the unwanted transfer of harmful materials to the environment. The chemical compositions of industrially produced glasses are in large part different from the compositions of natural glasses. Little is quantitatively known about the stability of industrial glasses over very long periods of time (>10,000 years). However, the physical and chemical stability of natural aluminosilicate glasses is known to extend over very long periods of time.The advancement of technological design to prevent or at least minimize the melt down of toxic waste during the encapsulation process is currently a major challenge, using glasses of natural chemical composition. Brecciated glass, which is found frequently in natural settings, provides a special clue to the possibility of producing vitreous solids by sintering glass fragments without melting the cullets. It is essential to prevent melting of the cullets because the melt has the potential of chemically reacting with the toxic waste.This paper summarizes the geological, chemical, and physical facts concerning naturally produced glasses, and seeks to establish a recognized database for further research in the domain of understanding the glass-forming processes that occur in nature. Furthermore, the authors hope to stimulate research into the utilization of natural resources that to solve the problem of storing of toxic waste safely.Major and trace element data have been collected over the past 100 years. These data constitute a sufficient basis for the chemical characterization of natural glasses. More information about the major elements is not required, in order to understand the chemical properties of these materials. On the other hand, large gaps in compositional data exist where other related components are concerned: e.g., in the case of “water-species”, with its different forms of bonding in silicates or oxygen (oxygen fugacity), CO₂-, sulphur - or hydrocarbons (methane)-, hydrogen-, chlorine-and fluorine-species. All these components have a significant impact on the properties of glasses, even when present only in minor quantities. Glass textures and crystal morphologies reflect the processes of nucleation and crystal growth in a glass-forming matrix during the cooling and reheating cycles which are currently not thoroughly understood. In nature, the processes that led to the formation of vitreous materials are very different from those used in the production of industrial glasses. The different genetic conditions under which glass formation occurs permit differentiation between magmatic and metamorphic vitreous solids. Sedimentary and biogenetic processes also contribute to the formation of non-crystalline solids.     

Northern Greece's industrial minerals: production and environmental technology developments

This paper reviews the use of Greek industrial minerals into developing low-cost, high-tech solutions to remediate parts of the chemical pollution environmental problem. The remediation strategy, based on the application and implementation of the Greek industrial minerals potential, became a major line of investigation in projects to develop new environmental technologies. Although past and current experiments have been successful on a lab scale in a number of applications, the results have not always been implemented on industrial scales. Greek olivine has been successfully tested as neutralizing agent for acid wastes, co-producing exploitable amounts of silica gel, magnesium sulphate and magnetite. Vermiculite is currently tested as an environmental ‘cleanser' in a variety of applications, i.e. metalliferous mine seepage and processing waters, organically contaminated waste water from the textile/dye industry and absorption material for oil spills. Wollastonite will be applied as long-term fertiliser and dolomite, as a substitute of asbestos in brake linings, as pollution controller of heavy metal concentrations in waste waters and as a binder to stabilize waste solids. Magnesite has been successfully applied for neutralization of acid mine wastes produced from active sulphide deposits. Zeolites (fly ash and perlite converted to zeolites were also considered) is an objective for several environmental applications, i.e. as floating absorbent for waste water ponds, as drinking water purificator or as smell abatement.     

Dissolved organic matter fluorescence spectroscopy as a tool to estimate biological activity in a coastal zone submitted to anthropogenic inputs

Here we report on an investigation of the three-dimensional excitation-emission-matrix (EEM) fluorescence spectra of unconcentrated water samples collected in 1996, 1998 and 1999 at a site particularly propitious for macro-algae development. The degradation of these macro-algae was studied to determine the influence of their exudates on natural water EEM fluorescence spectra. This work demonstrates that biological activity is one of the major factors involved in the formation of the blue-shifted fluorescence band observed in marine waters (β component Ex/Em=310–320 nm/380–410 nm); our study also shows that fluorescence can be used to evaluate the biological activity both quantitatively and to determine its different phases.     

地质钻探废弃冲洗液污染特性及脱稳技术研究

废弃冲洗液无害化处理是落实绿色勘查理念的一项重要工作。通过室内测试分析与现场调研,对地质钻探不同领域的钻孔废弃冲洗液进行污染特性研究,了解其基本性质以及对环境的影响方式。结合湘桃地2井废弃冲洗液开展脱稳技术室内研究,对破胶剂及絮凝剂进行了优选,并获得了脱稳处理的基础配方。实验结果表明,经过处理后废弃冲洗液能实现快速脱稳絮凝,COD、悬浮物、色度等污染指标大幅下降,为下一步深度处理实现无害化排放创造了有利条件。     

Organic components in thermally altered coal waste: Preliminary petrographic and geochemical investigations

The petrographic and geochemical composition of coal wastes exposed to fire in the minestone dump of Piekary Ślą¹skie town (Upper Silesia, Poland) was investigated using samples collected at various distances from a recent fire site. The question as to whether geochemical biomarker maturity parameters could be applied to assess thermal changes in organic matter caused by waste dump fires, was examined using the data obtained. Geochemical parameters were correlated with observed petrographic changes in the organic matter caused by oxidation and heating. Petrographic analyses included the determination of maceral group contents (vitrinite, liptinite and inertinite), mineral matter and coke contents, and reflectance measurements on organic matter. All results were supported by proximate and ultimate analyses. Geochemical analysis included ultrasonic solvent extraction of bitumen followed by gas chromatography–mass spectrometry (GC–MS) of the extracts. In petrographic terms, the influence of heating was seen in reflectance variations and as oxidation rims, cracks, pores and coke development. Some zoned oxidation rims may be interpreted as re-heating episodes. In terms of chemical fingerprints, less thermally-stable compounds such as lighter n-alkanes, cyclic isoprenoids, methyl- and dimethylnaphthalenes, methyphenanthrenes and five-ring polycyclic aromatic hydrocarbons were destroyed or evaporated in the most fire-affected material. The presence/absence of particular compound groups was used to assess heating temperatures. Biomarker parameters of thermal maturity were used to assess alterations in organic matter around the waste dump fires, especially those indices and ratios with higher maturity ranges, e.g. (3-methylbiphenyl + 4-methylbiphenyl)/dibenzofurane and Σdimethylbiphenyls/Σmethyldibenzofuranes.