Application of synthetic oxidants for intensification of uranium in-situ leaching process

Эта работа посвящена изучению процесса скважинного подземного выщелачивания (СПВ) урана и применению искусственных окислителей для его интенсификации. В ходе выполнения работы была создана термодинамическая модель процесса СПВ. Показано, что двухвалентное железо может являться восстановителем для ионов шестивалентного урана на стадии закисления новых технологических блоков. Проведены лабораторные испытания применения нитрита натрия и бихромата натрия для интенсификации выщелачивания урана из руды. Установлено, что применение этих окислителей позволяет повысить концентрацию урана в продуктивных растворах на 20-30%.This study investigated the process of in situ leaching (ISL) method of uranium mining, and the application of synthetic oxidants for intensification of uranium in-situ leaching process. Thermodynamic model of the ISL was created. It was shown that iron (II) may be a reducing agent for hexavalent uranium ion at the stage of acidification of new technological cells. Sodium nitrite and potassium dichromate were used in experiments carried out in laboratory. It was established that application of these oxidizing agents enables to increase the concentration of uranium in productive solutions on 20-30%.Программа развития УрФУ на 2013 год (п.2.1.1.1

Uranium stripping from tri-n-butyl phosphate by hydrogen peroxide solutions

The processes of uranium stripping from 30% tri-n-butyl phosphate (TBP) in "odorless" kerosene by H2O2 solutions both with and without NH4OH added were investigated in the temperature range of 20-50 C and with a volumetric ratio of 1 between the organic and aqueous phases. The uranium was selectively precipitated in the form of uranium peroxide during stripping from the organic phase by hydrogen peroxide. The stripping of uranium increased with increasing H2O2 content, increasing temperature and increasing concentration of NH3 in the range of 0-15 g/L. The use of a heated solution (40 C) that contained 4 mol H 2O2/mol U and NH3 12 g/L resulted in 99.7% of the uranium being stripped from TBP in the form of uranium peroxide. The uranium peroxide obtained by stripping is a highly pure product that exists in two different hydrated forms: UO4в̂™4H2O (92 mass %) and UO4в̂™2H2O. The mean particle diameter was 20.75 μm. The effect of hydrogen peroxide on the organic phase was studied by IR spectroscopy. No structural changes in TBP were observed after 30 cycles of extraction/stripping; thus, the use of hydrogen peroxide in this application is unrestricted. © 2013 Elsevier B.V

Rhizobacteria Effect on Arsenic Migration and Translocation of Biogenic Elements in Plants

The study was aimed at the transformation of arsenic compounds in the rhizosphere, its accumulation in plants, P and Si translocation to plants under the influence of Bacillus megaterium var. phosphaticum, and Bacillus mucilaginosus with various forms of As compounds in the soil. The authors describe the maximum effect of Bacillus megaterium var. Phosphaticum strain on As migration, its mobilization and immobilization in the rhizosphere due to arsenic leaching from mineral and difficult-todestroy compounds and its accumulation in plants. The forms of arsenic compounds were isolated from the rhizosphere based on sequential extraction procedures. The features of the inter-element As-P interaction in plants were established. With the intense accumulation of As in the rhizosphere inoculated with rhizobacteria, the intake of phosphorus into plants was not observed, as contrary to Si. The study of As and biogenic elements behavior under the influence of rhizobacteria is of great importance in the development of ecobiotechnologies related to soil remediation and crop production

Features of shear transformation texture in seamless pipes

Microstructure and texture in seamless 0.08C-Cr-Mo-V, 0.25C-Cr-Mo-V-Nb, 0.08-13Cr-3Ni-Mo-V-Nb, and 18Cr-9Ni steel pipes are studied in the as-rolled and heat-treated states using orientation EBSD microscopy. It has been found that all types of microstructure (ferrite, martensite, and bainite) in products, both after hot rolling and after heat treatment, have well-defined axial crystallographic texture, where the direction is predominately perpendicular to the pipe surface. It is demonstrated that texture formation in heat-treated states is inherited due to the following factors important for the rules of orientation selection during the γ→α phase transformation: 1) occurrence of stable orientation of austenite grains resulted from straining; 2) special misorientation (boundaries) of austenite grains where transformation starts; 3) orientation relationships known for phase transformation; 4) thermal stresses in a product, formed during cooling. The latter can be considered as factor determining special texture in seamless steel pipes. © 2018 Author(s)

The Role of Attention in Ambiguous Reversals of Structure-From-Motion

Multiple dots moving independently back and forth on a flat screen induce a compelling illusion of a sphere rotating in depth (structure-from-motion). If all dots simultaneously reverse their direction of motion, two perceptual outcomes are possible: either the illusory rotation reverses as well (and the illusory depth of each dot is maintained), or the illusory rotation is maintained (but the illusory depth of each dot reverses). We investigated the role of attention in these ambiguous reversals. Greater availability of attention – as manipulated with a concurrent task or inferred from eye movement statistics – shifted the balance in favor of reversing illusory rotation (rather than depth). On the other hand, volitional control over illusory reversals was limited and did not depend on tracking individual dots during the direction reversal. Finally, display properties strongly influenced ambiguous reversals. Any asymmetries between ‘front’ and ‘back’ surfaces – created either on purpose by coloring or accidentally by random dot placement – also shifted the balance in favor of reversing illusory rotation (rather than depth). We conclude that the outcome of ambiguous reversals depends on attention, specifically on attention to the illusory sphere and its surface irregularities, but not on attentive tracking of individual surface dots

THE EFFECT OF SULPHIDE MINERALS ON URANIUM VALENCE STATE AT IN-SITU LEACHING

The effect of sulphide minerals on uranium valence state at in-situ leaching was investigated. It was demonstrated that the reduction of uranium(VI) to uranium(IV) at pH < 4 is possible due to oxidation-reduction processes involving pyrite.The probability of uranium reduction by pyrite decreases with increasing pH of the leach solution.The reduction of uranium (VI) to uranium(IV) by pyrite at pH ≥ 4 is thermodynamically impossible.Исследование выполнено при финансовой поддержке РФФИ в рамках научного проекта № 16-33-00552 мол_а

Interaction of perceptual grouping and crossmodal temporal capture in tactile apparent-motion

Previous studies have shown that in tasks requiring participants to report the direction of apparent motion, task-irrelevant mono-beeps can &quot;capture'' visual motion perception when the beeps occur temporally close to the visual stimuli. However, the contributions of the relative timing of multimodal events and the event structure, modulating uni- and/or crossmodal perceptual grouping, remain unclear. To examine this question and extend the investigation to the tactile modality, the current experiments presented tactile two-tap apparent-motion streams, with an SOA of 400 ms between successive, left-/right-hand middle-finger taps, accompanied by task-irrelevant, non-spatial auditory stimuli. The streams were shown for 90 seconds, and participants' task was to continuously report the perceived (left-or rightward) direction of tactile motion. In Experiment 1, each tactile stimulus was paired with an auditory beep, though odd-numbered taps were paired with an asynchronous beep, with audiotactile SOAs ranging from -75 ms to 75 ms. Perceived direction of tactile motion varied systematically with audiotactile SOA, indicative of a temporal-capture effect. In Experiment 2, two audiotactile SOAs-one short (75 ms), one long (325 ms)-were compared. The long-SOA condition preserved the crossmodal event structure (so the temporal-capture dynamics should have been similar to that in Experiment 1), but both beeps now occurred temporally close to the taps on one side (even-numbered taps). The two SOAs were found to produce opposite modulations of apparent motion, indicative of an influence of crossmodal grouping. In Experiment 3, only odd-numbered, but not even-numbered, taps were paired with auditory beeps. This abolished the temporal-capture effect and, instead, a dominant percept of apparent motion from the audiotactile side to the tactile-only side was observed independently of the SOA variation. These findings suggest that asymmetric crossmodal grouping leads to an attentional modulation of apparent motion, which inhibits crossmodal temporal-capture effects