scholarly journals The impact of the compaction and mineralogical composition on the retention behaviour of Opalinus Clay

2020 ◽  
Vol 205 ◽  
pp. 13009
Author(s):  
Qazim Llabjani ◽  
Alessio Ferrari ◽  
Lyesse Laloui
Keyword(s):  
Mineralogical Composition ◽  
Opalinus Clay ◽  
Retention Behaviour ◽  
The Impact

scholarly journals Physico-chemical variability and heavy metal pollution of surface sediment in a non-channeled section of Dilúvio Stream (Southern Brazil) and the influence of channeled section in sediment pollution

2019 ◽  
Vol 14 (1) ◽  
pp. 1 ◽  
Author(s):  
Pedro Alexandre Sodrzeieski ◽  
Leonardo Capeleto de Andrade ◽  
Tales Tiecher ◽  
Flávio Anastácio de Oliveira Camargo
Keyword(s):  
Heavy Metals ◽  
Heavy Metal ◽  
Total Concentration ◽  
Mineralogical Composition ◽  
Sediment Pollution ◽  
Anthropogenic Influence ◽  
Southern Brazil ◽  
Physico Chemical ◽  
Chemical Variability ◽  
The Impact

Dilúvio Stream flows through an area with a great population density in Porto Alegre, Southern Brazil. The anthropogenic influence in the surroundings impacted negatively the quality of the sediments of Dilúvio Stream and Lake Guaíba. This study evaluated the physico-chemical variability of surface sediments in a non-channeled section of Dilúvio Stream. Additionally, we compared the concentration of several heavy metals in this section with data from previous studies in the margins of Lake Guaíba near the outflow of Dilúvio Stream in order to evaluate the impact of urbanization on sediment pollution. The pH, bulk density, particle-size distribution, electrical conductivity, organic carbon, assimilable phosphorus, total nitrogen, mineralogical composition (X-ray diffractogram) and pseudo total concentration of several metals (Fe, Al, Ca, Mg, Na, K, Mn, Ba, Zn, V, As, Pb, Cu, Cr, Co, Ni, Cd, Mo, and Se) were evaluated. The results showed that the sediments in the non-channeled section of Dilúvio Stream are predominantly sandy, with heavy metal contents below the quality reference values. Quartz and feldspar predominated in all sites. The concentration of Zn, Pb, Cu, Cr, and Ni were lower than that observed in the margins of Lake Guaíba near the outflow of Dilúvio Stream, possibly due to pollution input throughout the channeled section. The Dilúvio Stream shows indications of an anthropogenic influence in the heavy metals concentration through the channeled area.

Influence of Different Types of Fine Aggregate on Cement Composites Resistance to High Temperatures

2014 ◽  
Vol 1000 ◽  
pp. 126-129 ◽  
Author(s):  
Tomáš Melichar ◽  
Jiří Bydžovský
Keyword(s):  
Mineralogical Composition ◽  
Mechanical Tests ◽  
Basic Material ◽  
Fine Aggregate ◽  
Cement Composites ◽  
Cement Mortars ◽  
Different Types ◽  
Natural Aggregates ◽  
The Impact

The paper discusses the impact of several selected aggregates on the basic material characteristics of cement composites. Both artificial and natural aggregates (four types in total) with different mineralogical composition were evaluated. The specimens were exposed to environments with the temperature up to 1000°C and then subjected to physico-mechanical tests. For the follow-up development of polymer-cement mortars, we selected two types of aggregates – fly ash aggloporite (FAA) and amphibolite (AMA).

Mobilization, release and speciation of arsenic in an As-contaminated gold mine spoil under varied soil redox conditions

2020 ◽  
Author(s):  
Albert Kobina Mensah ◽  
Bernd Marschner ◽  
Jianxu Wang ◽  
Sabry M. Shaheen ◽  
Jörg Rinklebe
Keyword(s):  
Extraction Procedure ◽  
Mineralogical Composition ◽  
Redox Conditions ◽  
Mine Spoil ◽  
Residual Fraction ◽  
Reductive Dissolution ◽  
Gold Mine ◽  
Soil Redox ◽  
Reducing Conditions ◽  
The Impact

<p>Redox-induced release dynamics of arsenic (As) in an abandoned geogenic arsenic-contaminated gold mine spoil in Ghana has never been studied. Therefore, our aim was to investigate the effects of varied soil redox conditions on mobilisation and speciation of As from an abandoned highly contaminated gold mine spoil (with 4,283 mg As/kg soil) using an automated biogeochemical microcosm set-up. We also studied the impact of redox potential (E<sub>H</sub>)-dependent changes of pH, Fe, Mn, Al, S, Cl<sup>-</sup>, SO<sub>4</sub><sup>2-</sup>, DOC, DIC, DC, DN and SUVA on the release dynamics of As. As mineralogical composition and speciation were further determined using a synchrotron-based X-ray absorption spectroscopy (XANES). Linear combination fits of XANES results indicated that scorodite (FeAsSO<sub>4</sub>) and arsenopyrite (FeAsS) are the two major As-containing minerals in the studied mine spoil. Geochemical fractionation using sequential extraction procedure indicated greater proportions of the extracted As in the amorphous iron oxide fraction III (1390.13 mg kg<sup>-1</sup>, 32.5% of the total As) and residual fraction V (2591.67 mg kg<sup>-1</sup>, 60.5% of the total As). Concentrations of dissolved Fe and SUVA were higher during reducing conditions and decreased under oxidising conditions and both showed negative significant relationships with E<sub>H</sub> (E<sub>H </sub>and SUVA: r = -0.76, <em>P <</em> 0.01; E<sub>H</sub> and Fe: r = -0.75). Mobilisation of As was greater under reducing conditions (dissolved As = 136.68 mg/L) than in oxidising environments (dissolved As = 8.06 mg/L). The release of As under low E<sub>H</sub> can be explained by the associated reductive dissolution of Fe oxides, as demonstrated by the high positive significant relationship between Fe and As (r = +0.97, <em>P <</em> 0.01). Dissolved As release dynamics can also be linked to desorption of aromatic carbon compounds on the surfaces of dissolved organic carbon, as demonstrated by the high positive significant correlation between SUVA and As (r = +0.573, <em>P <</em> 0.01). Further, the release dynamics of dissolved As was also affected by changes in pH (r = -0.4, <em>P <</em> 0.05), but were not affected by redox-induced dynamics of Mn, Al, S, Cl<sup>-</sup>, SO<sub>4</sub><sup>2-</sup>, DOC, DIC, DC, DN. We conclude that conditions such as flooding and high rainfall in this contaminated mine spoil could create reducing conditions, leading to reductive dissolution of the arsenopyrite As-bearing primary mineral and may lead to higher As release into the groundwater, translocation into the food chain with potential impacts on human health.</p><p><strong>Keywords</strong>: Arsenopyrite, redox chemistry, arsenic mobilisation, gold mine spoil, reductive and oxidative dissolution.</p>

scholarly journals Mineral stability, brine development and rock-fluid reaction at repository-relevant temperatures (<i>T</i> < 200 °C) in the potential host rock rock salt

2021 ◽  
Vol 1 ◽  
pp. 101-102
Author(s):  
Michael Mertineit ◽  
Michael Schramm
Keyword(s):  
Melting Point ◽  
Rock Salt ◽  
Site Selection ◽  
Host Rock ◽  
Mineralogical Composition ◽  
Confining Pressure ◽  
Maximum Temperature ◽  
General Importance ◽  
Host Rocks ◽  
The Impact

Abstract. For a repository of heat generating radioactive waste, the thermal behaviour of the host rock and the impact of temperature increase on rock properties is of general importance. In the German Site Selection Act (2017), the maximum temperature of the container surface is preliminarily limited to 100 ∘C but this limit might change in the future based on scientific and technological findings. Rock salt, as one of the possible host rocks, consists predominantly of halite with varying amounts of accessory minerals (e.g., Hudec and Jackson, 2007); however, some lithological units within a salt deposit, e.g. potash seams, show a different mineralogical composition with high amounts of potash minerals. Most of them are not very stable regarding temperature resistance and stress, contain water in the crystal lattice, and therefore react sensitively to changes in the environment. The melting point of most evaporated minerals is higher than the expected temperatures in a repository but dehydration and partial melting might occur at relevant temperatures, depending on the confining pressure. For example, the temperature of dehydration of carnallite is ca. 80 ∘C at 0.1 MPa confining pressure but increases to ca. 145 ∘C at 10 MPa confining pressure (Kern and Franke, 1986). The melting point of carnallite increases from ca. 145∘C/8MPa to ca. 167∘C/24MPa, which corresponds to a depth of ca. 1000 m. Depending on the mineral paragenesis and composition of saline solutions, different minerals develop with increasing temperature. For instance, a salt rock with an initial composition of kieserite + kainite + carnallite + solution R (25 ∘C) reacts solely to kieserite and solution R, when the temperature increases to 78 ∘C. A rock with a composition of kieserite + carnallite + bischofite + solution Z (25 ∘C) reacts to kieserite + carnallite from 25 to 50 ∘C, from 50 to 73 ∘C only kieserite is stable, and at temperatures >73 ∘C kieserite and bischofite develop (Usdowski and Dietzel, 1998). For the construction of an underground repository, the mineralogical composition of the host rocks and fluids have to be evaluated carefully and play an important role for the site selection and design of the underground facility.

scholarly journals Impact of the heterogeneity of the sandy Opalinus clay facies at the Mont Terri underground research laboratory on radionuclide migration

2021 ◽  
Vol 1 ◽  
pp. 141-142
Author(s):  
Naila Ait-Mouheb ◽  
Yuankai Yang ◽  
Luc R. Van Loon ◽  
Martin A. Glaus ◽  
Guido Deissmann ◽  
...  
Keyword(s):  
Research Laboratory ◽  
Radioactive Wastes ◽  
Coupled Processes ◽  
Opalinus Clay ◽  
Nuclear Waste Repository ◽  
Radionuclide Transport ◽  
Mont Terri ◽  
Underground Research Laboratory ◽  
Host Rocks ◽  
The Impact

Abstract. The assessment of the safety of a deep geological repository (DGR) for high-level radioactive wastes over assessment time scales of up to 1 million years requires an in-depth understanding of the multi-scale coupled processes that affect the repository system evolution over time, to reduce uncertainties and conservatism in safety analyses. This is in particular required with respect to the challenges of a comparative assessment of different repository concepts in different host rocks within the process of a site selection for a DGR for heat-generating radioactive wastes in Germany. The collaborative project “Integrity of nuclear waste repository systems – Cross-scale system understanding and analysis (iCross)” conducted jointly by five research centres of the Helmholtz Association and co-funded by the Initiative and Networking Fund of the Helmholtz Association and the Federal Ministry of Education and Research (BMBF) has been initiated with the overall objective to improve the understanding of coupled thermal-hydraulic-mechanical-chemical-(micro)biological (THMCB) processes and to develop simulation tools that enable a holistic close to reality description of the long-term evolution of the repository system. Geological formations, such as those foreseen as potential host rocks for DGRs, and their surroundings are heterogeneous on various length scales ranging from nanometers to kilometers. Therefore, the aim of this work in the context of iCross is to evaluate the effects of mineralogical, geochemical and microstructural heterogeneities of repository host rocks on radionuclide transport in the repository far field, using the sandy facies of the Opalinus clay (SF-OPA) from the Mont Terri underground research laboratory (St. Ursanne, Switzerland) as an example. Here, we address in particular the migration behaviour of Ra-226 as an important radionuclide to be considered in safety cases for deep geological disposal of spent nuclear fuel. To assess the impact of the heterogeneities in SF-OPA on radionuclide transport, a complementary approach combining microstructural characterisation methods, experimental techniques for the determination of transport parameters of the rock matrix and the mobility of Ra-226 with innovative developments in reactive transport modelling on the pore and continuum scales was pursued. One of the results was that although the limited clay content in SF-OPA decreases the total amount of Ra bound to the illite phase, the solid solutions of sulphate and carbonate compensate for this and provide a major fixation mechanism.

Bioleaching of Supergene Porphyry Copper Ores from Sungai Mak Gorontalo of Indonesia by an Iron- and Sulfur-Oxidizing Mixotrophic Bacterium

2017 ◽  
Vol 262 ◽  
pp. 20-23
Author(s):  
Siti Khodijah Chaerun ◽  
Frideni Yushandiana Putri ◽  
Mohammad Zaki Mubarok ◽  
Wahyudin Prawira Minwal ◽  
Zela Tanlega Ichlas
Keyword(s):  
Environmental Concern ◽  
Porphyry Copper ◽  
Environmentally Friendly ◽  
Mineralogical Composition ◽  
Extraction Process ◽  
Appropriate Technology ◽  
Copper Extraction ◽  
Sulfur Oxidizing ◽  
The Impact ◽  
Copper Ores

Environmentally friendly mining technologies have to be developed extensively to avoid the impact of mining activities with respect to environmental concern. One example of such technology is bioleaching which has been developed worldwide and is regarded as an appropriate technology for the extraction of metals from polymetallic ores such as supergene porphyry copper ores, mainly consisting of secondary copper sulfides, including chalcocite (Cu2S), covellite (CuS), or oxide minerals, i.e., cuprite (Cu2O) and tenorite (CuO). The extraction process for this complex ore generally requires high temperature, high pressure and/or high acid concentration. For the economic extraction of valuable copper from such ores, the bioleaching of supergene porphyry copper ore from Sungai Max in Southeast Sulawesi of Indonesia was investigated in shake-flask experiments at room temperature (28 °C) for 14 days using an iron- and sulfur-oxidizing bacterium (Alicyclobacillus sp.) indigenous to an Indonesian mine site. The main mineralogical composition of gangue minerals contained in this ore sample included quartz, muscovite, kaolinite and alunite. The relatively high copper extraction efficiencies were obtained over a 14-day period of the bioleaching experiments as a function of pH, pulp density and NaCl concentration. Therefore, the findings of this study provide the first information of bioleaching process of supergene porphyry copper ores in Indonesia that may highly be useful for developing an economical and environmentally friendly extraction process of such complex ores.

scholarly journals Abrasive Wear Resistance of Concrete in Connection with the Use of Crushed and Mined Aggregate, Active and Non-Active Mineral Additives, and the Use of Fibers in Concrete

2020 ◽  
Vol 12 (23) ◽  
pp. 9920
Author(s):  
Lenka Bodnárová ◽  
Martin Ťažký ◽  
Lucia Ťažká ◽  
Rudolf Hela ◽  
Ondřej Pikna ◽  
...  
Keyword(s):  
Abrasion Resistance ◽  
Age Groups ◽  
High Strength ◽  
Mineralogical Composition ◽  
Concrete Mixtures ◽  
Standard Procedures ◽  
Different Types ◽  
The Impact ◽  
Mineral Additives ◽  
Active Mineral Additives

Virtually every concrete structure comes into contact with abrasive effects of flowing media or solids, which have a direct impact on the durability of concrete. An abrasive effect is most pronounced in transport or water management structures, and these structures are often designed for a significantly longer service life (usually 100 years). This research evaluates the influence of the filler component in terms of the type of aggregate and its mineralogical composition on concrete abrasion resistance. As part of the impact of the binder component, several concrete mixtures were produced using the same aggregate and maintaining the same strength class with the addition of different types of active and inert mineral additives. In other parts of the research, the effect of adding fiber reinforcement on the abrasion resistance of concrete was verified. Mutual connections and correlations in different age groups (7, 28 and 90 days) were sought for all obtained results. The abrasion resistance of the composite was monitored by using standard procedures, especially using a Böhm device. It was found that for good abrasion resistance of concrete, it is not necessary to produce concretes with high strength classes using often expensive mineral additives (microsilica) and quality aggregates, but the maturation time of the composite and its microstructure plays an important role.

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