Rare earths are used in the renewable energy technologies such as wind turbines, batteries, catalysts and electric cars. Current mining, processing and sustainability aspects have been described in this paper. Rare earth availability is undergoing a temporary decline due mainly to quotas being imposed by the Chinese government on export and action taken against illegal mining operations. The reduction in availability coupled with increasing demand has led to increased prices for rare earths. Although the prices have come down recently, this situation is likely to be volatile until material becomes available from new sources or formerly closed mines are reopened. Although the number of identified deposits in the world is close to a thousand, there are only a handful of actual operating mines. Prominent currently operating mines are Bayan Obo in China, Mountain Pass in the US and recently opened Mount Weld in Australia. The major contributor to the total greenhouse gas (GHG) footprint of rare earth processing is hydrochloric acid (ca. 38%), followed by steam use (32%) and electricity (12%). Life cycle based water and energy consumption is significantly higher compared with other metals.
برای بررسی ارتباط میان اجزای نظارتی و اجرایی معدن و به منظور بهبود سطح ایمنی سیستم، این مقاله روش جدیدی را برای ارزیابی و مدیریت ایمنی سیستم معادن معرفی میکند. بدین منظور در این مقاله از کاربرد نظریه بازیها برای حل مسایل ایمنی معادن استفاده شده است. نظریه بازیها ابزار ساختاریافتهای است که تعاملات بین دو یا چند بازیکن را بررسی میکند تا اقدامات آنها را در شرایط معین درک کند. در این مقاله از بازی تکاملی به دلیل بیان پویایی روابط میان بازیکنان، استفاده شده است. مدل معرفی شده تعاملات بین دولت، مدیران و معدنچیان را تحت شرایط مختلف شبیهسازی میکند و تأثیر عوامل نظارتی بر آنها در سیستم ارزیابی میشود. نتایج نشان میدهد که تاثیر هر عامل بر ایمنی سیستم متفاوت است و بازیکنان، متناسب با هر عامل نظارتی بر ایمنی سیستم تاثیر میگذارند. از جمله این عوامل، تاثیرگذاری جریمههای اعمالی ناظر بازی بر رفتار مدیریت معدن و کارگران معدن در بیشترین میزان بود. به طوری که با افزایش جریمهها، بازیکنان در زمان کوتاهی استراتژیهای همسو با تولید ایمن را در پیش گرفتند. در ادامه تاثیر مشوقهای دولتی نیز بررسی و مشخص شد که به ازای افزایش ضریب پاداش به مدیریت و کارگران معدن تغییر استراتژی و تولید ایمن در معدن برقرار خواهد شد.
A.V. Kasatkin, S.Yu. Stepanov, M.V. Tsyganko
et al.
The Vorontsovskoe gold deposit (Northern Urals) is unique in both Russia and the world because of the diverse and original Tl–Hg–Mn–As–Sb–S mineralization. Based on the available literature and our data, we present a list of 210 minerals found at this deposit. Eight of them are new minerals discovered by the authors: vorontsovite, ferrovorontsovite, tsygankoite, gladkovskyite, luboržákite, pokhodyashinite, gungerite, and auerbakhite. In addition, 41 minerals are found for the first time in the Russian Federation and 89 minerals are new for the deposit. We defined nine major ore mineral assemblages, including seven ones related to carbonate breccias. They contain more than 70 rare sulfides, tellurides and sulfosalts, including 31, 12, and 9 minerals with Tl, Hg and Mn, respectively, as species-defining elements. The paper also describes these mineral assemblages and minerals of the Vorontsovskoe deposit.
The dynamic response of rocks to thermal, hydrodynamical, mechanical, and geochemical solicitations is of fundamental interest in several disciplines of geosciences, including geo-engineering, geophysics, rock physics, hydrology, mineralogy, and environmental and soil sciences. From crystal shape to rock microstructure or pore space and fluid distribution, parameters characterizing the rock physico-chemical properties evolve at different time and spatial scales. X-ray micro-tomography (XMT), as a non-invasive and non-destructive imaging technique, offers an unprecedented opportunity to add the fourth dimension, i.e. time, to the three-dimensional spatial visualization of rock and mineral microstructures. The technique is increasingly used to explore dynamic processes in porous and fractured rocks, thanks to synchrotron sources and laboratory XMT scanners, new generations of detectors, and increasing computational power. Image processing allows for tracking the evolution of the fluid–fluid or fluid–mineral interfaces as well as measuring incremental deformations, as rocks deform and react through time under in situ conditions of the sub-surface. Here, we review recent advances in 4D X-ray micro-tomography applied to thermo-hydro-mechano-chemical (THMC) sub-surface processes where fluids, porosity, minerals, and rock microstructures evolve together.
Caitlin P. Casar, Brittany R. Kruger, Magdalena R. Osburn
The continental deep subsurface is likely the largest reservoir of biofilm-based microbial biomass on Earth, but the role of mineral selectivity in regulating its distribution and diversity is unclear. Minerals can produce hotspots for intraterrestrial life by locally enhancing biofilm biomass. Metabolic transformations of minerals by subsurface biofilms may occur widely with the potential to significantly impact subsurface biogeochemical cycles. However, the degree of impact depends upon the amount of biofilm biomass and its relationship to host rock mineralogy, estimates that are currently loosely constrained to non-existent. Here, we use in situ cultivation of biofilms on native rocks and coupled microscopy/spectroscopy to constrain mineral selectivity by biofilms in a deep continental subsurface setting: the Deep Mine Microbial Observatory (DeMMO). Through hotspot analysis and spatial modeling approaches we find that mineral distributions, particularly those putatively metabolized by microbes, indeed drive biofilm distribution at DeMMO, and that bioleaching of pyrite may be a volumetrically important process influencing fluid geochemistry at this site when considered at the kilometer scale. Given the ubiquity of iron-bearing minerals at this site and globally, and the amount of biomass they can support, we posit that rock-hosted biofilms likely contribute significantly to subsurface biogeochemical cycles. As more data becomes available, future efforts to estimate biomass in the continental subsurface should incorporate host rock mineralogy.
Erol Sarı, Mustafa Kumral, Mehmet Fatih Hüseyinoğlu
et al.
The study area covers the northern coasts of Cyprus from the Güzelyurt Gulf to the Gazimağusa Gulf. This study was carried out in order to reveal the presence of the alien foraminifera, which are widely distributed in the Eastern Mediterranean particularly Amphistegina lobifera in the study area, and the effects of trace elements on faunal assemblages (foraminifera, ostracod and mollusc). The bottom sediment samples were taken from eighteen different points and depths, the faunal assemblages were examined, and the sediment distribution map of the studied area was made by ICP-MS analysis and geochemical evaluations. 30 genera and 48 species of foraminifera have been identified, of which 9 species belonging to 6 genera are the alien foraminifera. These are: Spiroloculina angulosa, S. antillarum, Hauerina diversa, Coscinospira hemprichii, Peneroplis pertusus, P. planatus, Amphisorus hemprichii, Sorites orbiculus and Amphistegina lobifera. Amphistegina lobifera was observed to be abnormally abundant in most of the samples. This foraminiferal assemblage of Red Sea origin constitutes a poor assemblage compared to the alien assemblages in Turkish Mediterranean coastal areas. It has been determined that the ostracod and mollusc genera and species found in the same samples belong to the typical Mediterranean and Aegean Sea community.
Ondřej Holubík, Aleš Vaněk, Martin Mihaljevič
et al.
Thallium (Tl) is a toxic trace element with a highly negative effect on the environment. For phytoextraction purposes, it is important to know the limitations of plant growth. In this study, we conducted experiments with a model Tl-hyperaccumulating plant (Sinapis alba L., white mustard) to better understand the plant tolerance and/or associated detoxification mechanisms under extreme Tl doses (accumulative 0.7/1.4 mg Tl, in total). Both the hydroponic/semi-hydroponic (artificial soil) cultivation variants were studied in detail. The Tl bioaccumulation potential for the tested plant reached up to 1% of the total supplied Tl amount. Furthermore, it was revealed that the plants grown in the soil-like system did not tolerate Tl concentrations in nutrient solutions higher than ~1 mg/L, i.e., wilting symptoms were evident. Surprisingly, for the plants grown in hydroponic solutions, the tolerable Tl concentration was by contrast at least 2-times higher (≥ 2 mg Tl/L), presumably mimicking the K biochemistry. The obtained hydroponic/semi-hydroponic phytoextraction data can serve, in combination, as a model for plant-assisted remediation of soils or mining/processing wastes enriched in Tl, or possibly for environmental cycling of Tl in general.
make up about 50% of the volume of most soils. They provide physical support for plants, and create the water- and air-filled pores that make plant growth possible. Mineral weathering releases plant nutrients that are retained by other minerals through adsorption, cation exchange, and precipitation. Minerals are indicators of the amount of weathering that has taken place, and the presence or absence of particular minerals gives clues as to how soils formed. The physical and chemical charac teristics of soil minerals are important considerations in planning, con structing, and maintaining buildings, roads, and airports.
Abstract Determining the mineralogy of mature sedimentary rocks, particularly mudrock, often defaults to qualitative or semi-quantitative methods due to difficulties in correctly quantifying multiple unknown mineral phases. Constraining mineral abundances is particularly difficult in shale due to preferred mounting orientation of common phyllosilicate phases, commonly leading to overestimation of clay minerals and mica. We introduce a quantitative approach to constraining mineralogy within mudrock by integrating x-ray diffraction (XRD) and x-ray fluorescence (XRF) data sets collected on splits of the same samples. The technique involves partitioning XRF cation concentrations into XRD-identified silicate, carbonate, and sulfide phases, then estimating quartz by XRF SiO2 balance. This method is applied to an example dataset from the economically significant Marcellus Shale (Middle Devonian, Appalachian Basin, USA). Conventional reference-intensity ratio (RIR) interpretation identified nine mineral phases (quartz, muscovite, illite, pyrite, chlorite, albite, calcite, dolomite, and barite). Their abundances were then re-estimated using more highly accurate XRF-derived elemental concentrations with stoichiometry from the identified XRD reference phases. XRF Al2O3 was used to corroborate the calculated XRD-XRF results for quality control. Errors in relevant XRF concentrations can be quantified, though not the assumptions in how they are employed; nonetheless, the resulting XRD-XRF mineralogic abundances by this procedure are thought to be more accurate than RIR and to remove preferred-orientation bias induced that causes overestimation of clay minerals and mica and underestimation of quartz and other phases. Cluster analysis of the XRD-XRF results identified four mineralogical facies that provide insight into potential primary depositional controls on organic-matter preservation within the Marcellus Shale. This XRD-XRF integration method provides a general framework for estimating mineralogy quantitatively in mudrocks, although dataset-specific adjustments to the method may be required for different mineralogical suites.
Abstract The present study describes the calcium adsorption behavior of clays exhibiting distinct mineralogical composition. The adsorption characteristics were determined using conventional batch-equilibrium sorption method, and different theoretical models were applied to describe the equilibrium sorption isotherms. The variation in calcium adsorption capacity was determined as a function of clay mineralogy, temperature and pore fluid chemistry. Further, the thermodynamic parameters were also calculated to describe the nature of adsorption mechanisms. Significant variation in calcium adsorption potential was observed among the clays, primarily attributed to their mineralogical diversities and related unique surface charge properties. The adsorption density escalated with rise in calcium concentration, temperature and pH of the adsorption system. These observations can be attributed to surface charge modifications and mineral dissolution properties of the clays, which in turn resulted in higher electro-negativity of the clay surface and thereby enhancing the affinity for calcium ions.