scholarly journals Chemical Composition and Petrogenetic Implications of Apatite in the Khibiny Apatite-Nepheline Deposits (Kola Peninsula)

Minerals ◽  
2018 ◽  
Vol 8 (11) ◽  
pp. 532 ◽  
Author(s):  
Lia Kogarko
Keyword(s):  
Vertical Section ◽  
Alkaline Complex ◽  
High Concentration ◽  
Magmatic Chamber ◽  
Alkaline Magma ◽  
Compositional Evolution ◽  
Eu Anomaly ◽  
Significant Enrichment ◽  
World Class

Khibiny, one of the largest of the world’s peralkaline intrusions, hosts gigantic apatite deposits. Apatite is represented by F-apatite and it contains exceptionally high concentration of SrO. (4.5 wt % on average) and increased amounts of rare earth elements (REEs; up to 8891 ppm). Such enrichment of apatite ores in REEs defined Khibiny deposit as world-class deposit with resources reaching several millions tons REE2O3. Apatite from the Khibina alkaline complex is characterized by the significant enrichment in light REEs relative to the heavy REEs (with average Ce/Yb ratio of 682) and the absence of a negative Eu anomaly. The obtained geochemical signature of apatite suggests a residual character of the Khibiny alkaline magma and it indicates that the differentiation of the primary olivine-melanephelinitic magma developed without fractionation of plagioclase which is the main mineral-concentrator of Sr and Eu in basaltic magmatic systems. The compositional evolution of the Khibiny apatite in the vertical section of the intrusion reflects primary fractionation processes in the alkaline magma that differentiated in situ. The main mechanism for the formation of the apatite-nepheline deposits was the gravitational settling of large nepheline crystals in the lower part of the magma chamber, while very small apatite crystals were suspended in a convective magma, and, together with the melt, were concentrated in its upper part of the magmatic chamber.

Compositional evolution and cryptic variation in pyroxenes of the peralkaline Lovozero intrusion, Kola Peninsula, Russia

2006 ◽  
Vol 70 (4) ◽  
pp. 347-359 ◽  
Author(s):  
L. N. Kogarko ◽  
C. T. Williams ◽  
A. R. Woolley
Keyword(s):  
Kola Peninsula ◽  
Temperature Interval ◽  
Magma Chamber ◽  
Vertical Section ◽  
Redox Conditions ◽  
Alkaline Magma ◽  
Compositional Evolution ◽  
Cryptic Variation ◽  
Alkaline Massif

AbstractThe Lovozero alkaline massif is the largest of the world's layered peralkaline intrusions (∼650 km2). We describe the evolution of clinopyroxene from the liquidus to the late residual stage throughout the whole vertical section (2.5 km thick) of the Lovozero Complex. Microprobe data (∼990 analyses) of the clinopyroxenes define a relatively continuous trend from diopside containing 15–20% hedenbergite and 10–12% aegirine components, to pure aegirine. The main substitutions during the evolution of the Lovozero pyroxenes are (Na,Fe3+,Ti) for (Ca,Mg,Fe2+). The composition of the pyroxene changes systematically upwards through the intrusion with an increase in Na, Fe3+ and Ti and decrease in Ca and Mg.The compositional evolution of the Lovozero pyroxene reflects primary fractionation processes in the alkaline magma that differentiated in situ from the bottom to the top of the magma chamber as a result of magmatic convection, coupled with the sedimentation of minerals with different settling velocities.The temperature interval of pyroxene crystallization is very wide and probably extends from 970 to 450°C. The redox conditions of pyroxene crystallization in the Lovozero intrusion were relatively low, approximating the QFM buffer.

scholarly journals Start-up Strategies for Anaerobic Ammonia Oxidation (Anammox) in In-Situ Nitrogen Removal from Polluted Groundwater in Rare Earth Mining Areas

2021 ◽  
Vol 13 (8) ◽  
pp. 4591
Author(s):  
Shuanglei Huang ◽  
Daishe Wu
Keyword(s):  
Rare Earth ◽  
Low Temperature ◽  
Removal Efficiency ◽  
Nitrogen Removal ◽  
Ex Situ ◽  
High Concentration ◽  
Low Concentration ◽  
Start Up ◽  
Anammox Activity

The tremendous input of ammonium and rare earth element (REE) ions released by the enormous consumption of (NH4)2SO4 in in situ leaching for ion-adsorption RE mining caused serious ground and surface water contamination. Anaerobic ammonium oxidation (anammox) was a sustainable in situ technology that can reduce this nitrogen pollution. In this research, in situ, semi in situ, and ex situ method of inoculation that included low-concentration (0.02 mg·L−1) and high-concentration (0.10 mg·L−1) lanthanum (La)(III) were adopted to explore effective start-up strategies for starting up anammox reactors seeded with activated sludge and anammox sludge. The reactors were refrigerated for 30 days at 4 °C to investigate the effects of La(III) during a period of low-temperature. The results showed that the in situ and semi in situ enrichment strategies with the addition of La(III) at a low-concentration La(III) addition (0.02 mg·L−1) reduced the length of time required to reactivate the sludge until it reached a state of stable anammox activity and high nitrogen removal efficiency by 60–71 days. The addition of La(III) promoted the formation of sludge floc with a compact structure that enabled it to resist the adverse effects of low temperature and so to maintain a high abundance of AnAOB and microbacterial community diversity of sludge during refrigeration period. The addition of La(III) at a high concentration caused the cellular percentage of AnAOB to decrease from 54.60 ± 6.19% to 17.35 ± 6.69% during the enrichment and reduced nitrogen removal efficiency to an unrecoverable level to post-refrigeration.

Hydrogen-induced amorphization and embrittlement resistance in Ti-based in situ composite with bcc-phase in an amorphous matrix

2007 ◽  
Vol 22 (2) ◽  
pp. 428-436 ◽  
Author(s):  
S. Jayalakshmi ◽  
J.P. Ahn ◽  
K.B. Kim ◽  
E. Fleury
Keyword(s):  
Hydrogen Embrittlement ◽  
Amorphous Alloys ◽  
Amorphous Matrix ◽  
Mechanical Tests ◽  
High Concentration ◽  
High Hydrogen ◽  
In Situ Composite ◽  
Bcc Phase ◽  
Embrittlement Resistance

We report the hydrogenation characteristics and mechanical properties of Ti50Zr25Cu25 in situ composite ribbons, composed of β-Ti crystalline phase dispersed in an amorphous matrix. Upon cathodic charging at room temperature, high hydrogen absorption up to ∼60 at.% (H/M = ∼1.2) is obtained. At such a high concentration, hydrogen-induced amorphization occurs. Mechanical tests conducted on the composite with varying hydrogen concentrations indicate that the Ti50Zr25Cu25 alloy is significantly resistant to hydrogen embrittlement when compared to conventional amorphous alloys. A possible mechanism that would contribute toward hydrogen-induced amorphization and hydrogen embrittlement is discussed.

Phosphate biogeochemical barrier for uranium in situ immobilization in an aquifer nearby sludge repository

2021 ◽  
Author(s):  
Grigory Artemiev ◽  
Alexey Safonov ◽  
Nadezhda Popova
Keyword(s):  
Essential Elements ◽  
Ion Concentration ◽  
Soluble Form ◽  
High Concentration ◽  
Rapid Reduction ◽  
Near Surface ◽  
Nitrate Ions ◽  
Uranium Migration ◽  
Storage Facilities

<p>Uranium migration in the oxidized environment of near-surface groundwater is a typical problem of many radiochemical, ore mining and ore processing enterprises that have sludge storage facilities on their territory. Uranium migration, as a rule, occurs against a high salt background due to the composition of the sludge: primarily, nitrate and sulfate anions and calcium cations. One of the ways to prevent the uranium pollution is geochemical or engineering barriers. For uranium immobilization, it is necessary to create conditions for its reduction to a slightly soluble form of uraninite and further mineralization, for example, in the phosphate form. An important factor contributing to the rapid reduction of uranium is a in the redox potential decreasing and the removal of nitrate ions, which can be achieved through the activation of microflora. It should be added that phosphate itself is one of the essential elements for the development of microflora. This work was carried out in relation to the upper aquifer (7-12 m) near the sludge storage facilities of ChMZ, which is engaged in uranium processing and enrichment. One of the problems of this aquifer, in addition to the high concentration of nitrate ions (up to 15 g / l), is the high velocity of formation waters.<br>In laboratory conditions, the compositions of injection solutions were selected containing sources of organic matter to stimulate the microbiota development and phosphates for uranium mineralization. When developing the injection composition, special attention was paid to assessing the formation of calcite deposits in aquifer conditions to partially reduce the filtration parameters of the horizon and reduce the rate of movement of formation waters. This must be achieved to ensure the possibility of long-term deposition of uranium and removal of nitrate. The composition of the optimal solution was selected and in a series of model experiments the mineral phases containing the lowest hydrated form of the uranium-containing phosphate mineral meta-otenite were obtained.<br>In situ mineral phosphate barrier Formation field tests were carried out in water horizon conditions in a volume of 100m3 by injection of an organic and phosphates mixture. As a result, at the first stage of field work, a significant decreasing nitrate ion concentration, and reducing conditions formation coupled with the dissolved uranium concentration of decreasing were noted.</p>

In situ Enclosure Experiment Using a Benthic Chamber System to Assess the Effect of High Concentration of CO2 on Deep-Sea Benthic Communities

2005 ◽  
Vol 61 (5) ◽  
pp. 835-843 ◽  
Author(s):  
Hiroshi Ishida ◽  
Yuji Watanabe ◽  
Tatsuo Fukuhara ◽  
Sho Kaneko ◽  
Kazushi Furusawa ◽  
...  
Keyword(s):  
Deep Sea ◽  
Benthic Communities ◽  
Chamber System ◽  
High Concentration ◽  
Enclosure Experiment ◽  
Benthic Chamber

scholarly journals Occurrence of Penta-Aromatic Hydrocarbons in Jaintia and Barail Group Mudstones, Northeastern Bengal Basin, Bangladesh

2014 ◽  
Vol 8 ◽  
pp. 105-112
Author(s):  
HM Zakir Hossain ◽  
Md Sultan-Ul-Islam ◽  
Quazi Hasna Hossain
Keyword(s):  
Aromatic Hydrocarbon ◽  
Aromatic Hydrocarbons ◽  
Concentration Distribution ◽  
Gas Chromatography Mass Spectrometry ◽  
Bengal Basin ◽  
Drill Core ◽  
Environmental Condition ◽  
High Concentration ◽  
Biogenic Origin

In the present experiment, concentration, distribution and sources of penta-aromatic hydrocarbons in seven drill core and outcrop samples from Jaintia and Barail Group mudstones, northeastern Bengal Basin, Bangladesh have been studied. Gas chromatography-mass spectrometry (GC-MS) was used to obtain composition details about the sedimentary organic matter (OM). Mudstone samples were found to contain relatively high penta-aromatic hydrocarbon abundances in the lower Jaintia Group than in the overlying Barail Group. High concentration of perylene suggests terrigenous sources and significantly higher content of total organic carbon in the samples. A biogenic origin of perylene therefore indicates oxygen deficient environmental condition for deposition of OM. Perylene over pentacyclic aromatic hydrocarbon isomers regulating in-situ diagenetic origin. DOI: http://dx.doi.org/10.3329/jles.v8i0.20154 J. Life Earth Sci., Vol. 8: 105-112, 2013

Preparation of Silicalite-1 Membranes on α-Al2O3 Tubes and its Concentration Performance of Low Ethanol/water Mixtures

2012 ◽  
Vol 608-609 ◽  
pp. 1337-1341
Author(s):  
Hong Liang Chen ◽  
Ji Song Yang ◽  
Yan Wang ◽  
Hui Ying Li ◽  
Xin Xin Li ◽  
...  
Keyword(s):  
Hydrothermal Synthesis ◽  
Solution Concentration ◽  
High Concentration ◽  
Separation Selectivity ◽  
Naoh Solution

Silicalite-1 membranes were successfully synthesized on α-Al2O3 tubes by in-situ hydrothermal synthesis after filling the tubes with water and glycerol mixtures, and all the membranes show high concentration performance towards ethanol/water mixtures after pretreating tubes with different NaOH solution. The results show that the flux enhances with the enhancement of NaOH solution concentration, but the separation selectivity decreases with the enhancement of NaOH solution concentration. After pretreating the α-Al2O3 tubes with different NaOH solution, the weight of all the α-Al2O3 tube decreases, but the Si/Al ratio increases, which shows that suitable pretreatment of α-Al2O3 is useful for improving the hydrophobicity of silicalite-1 membranes.

scholarly journals Pengembangan Metode DGT (Diffusive Gradient In Thin Film) dengan Binding Gel Fe-Al-Oksida dan Pengikat Silang N,N’-Methylenebisacrylamide untuk Penyerapan Fosfat dalam Air

2015 ◽  
pp. 20-25
Author(s):  
Asep Saefumullah ◽  
Ratsania Rahmaniati H
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Small Molecule ◽  
Aquatic Environment ◽  
Contact Time ◽  
Measurement Method ◽  
High Concentration ◽  
Accurate Analysis ◽  
Al Oxide

High concentration of phosphates in the water can lead to eutrophication which leads to uncontrolled growth of algae (algae blooming). It underlies the need for determining the concentration of phosphate in the aquatic environment. However, the concentration of phosphate may change during storage of samples so that an accurate analysis difficult to achieve unless carried out in-situ. DGT (Diffusive Gradient in Thin Films) is an in-situ measurement method developed for measuring phosphate and metal. In this study the use of Fe-Al-Oxide as a binding gel that is expected to bind phosphate with a capacity greater than ferrihydrite. N, N'-methylenebisacrylamide is used as a substitute for commercial DGT Crosslinker as crosslinking for a cheaper price and selective for small molecule. Ferrihydrite-DGT and Fe-Al-Oxide-DGT are tested with a variety of concentrations, pH, and contact time. In both methods DGT found that the pH for phosphate measurements performed at pH 3. Capacity of Fe-Al-Oxide binding gel known to be higher than the ferrihydrite binding gel with result Cferrihydrite-DGT:Cstart is 76% and CFe-Al-Oxide-DGT:Cstart is 82%.DOI :http://dx.doi.org/10.15408/jkv.v0i0.3597

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