Vol 50, No 5 (2016)

The kinetics of mass transfer in the extractive distillation of the benzene–heptane mixture (which imitates the catalytic reforming product mixture) in the presence of N-methylpyrrolidone as the separating agent has been investigated. The separating agent exerts an effect on the overall efficiency of the process. The partial heights of transfer units in the vapor and liquid have been determined, and equations for calculating these parameters have been set up.

Some results of studying the mass-transfer characteristics of random stainless steel spiral prismatic packings in the separation of hydrogen and oxygen isotopes via vacuum water distillation in columns of 60 and 120 mm in diameter have been reported. The effect of the size of the packing element and the pressure on the ultimate throughput and the height equivalent to a theoretical plate has been shown.

The extractive rectification of a butyl butyrate–butyric acid mixture under reduced and atmospheric pressures has been studied by mathematical simulation using the Aspen Plus^® v.8.0 software package. It has been shown that, from an energy point of view, extractive rectification of a butyl butyrate–butyric acid mixture should be performed under reduced pressure (e.g., 140 mm Hg) when this mixture is biazeotropic, rather than under atmospheric pressure when the system is zeotropic.

Some methods for purifying reprocessed uranium from the admixture ^{232, 234, 236}U isotopes in ordinary and double cascades have been considered. The method of purification in a matched abundance ratio cascade (MAR cascade) with a considerable decrease in the ^{232, 234}U concentration in its additional product flow and separation of low-enriched uranium in the main product flow has been proposed. A computational experiment was performed. The results of calculations for MAR cascades with different key uranium isotopes have been presented. The variant that is best for the further enrichment of the purified product in an isolated cascade has been selected.

The scientifically based selection of efficient chemical technologies is related to the integrated assessment of indicators of their energy and resource efficiency and environmental safety, as well as indicators of the quality of products. The authors conducted systematic analysis of the efficiency and competitiveness of two electrochemical technologies of chroming from the solutions based on chromium salts of different valences. The strengths and weaknesses of each technology have been defined using the methodology of SWOT analysis, and the defined qualitative indicators of the efficiency of technologies have been determined using the methods of nonparametric statistics.

An experimental study has been performed on the effect of the temperature of gas and water droplets (3–6 mm in size) on deformation of water droplets that move with a moderate velocity (up to 5 m/s). A high-speed videocamera (recording at up to 10⁵ fps) and a cross-correlation videocomplex were used. The droplet temperature varied in the range of 285–360 K. For gaseous mediums, air at a temperature of 280–300 K and condensed substance combustion products at a temperature about 1100 K were used. Typical deformation cycles were found. Their length, duration, and amplitude were calculated. The time a shape of droplet transforms into a new shape and the time the droplets retain their shape as they move through a gas medium have been determined. Approximating correlations for the basic characteristic of deformation under various heating or cooling conditions in a water droplet–gas system were derived.

A physical and mathematical model has been developed for the cooling of a block of receiver tanks for uranium hexafluoride desublimation with cold air supplied to heat exchangers by a VKhM-0.54/0.6 air cooler. Calculations have been carried out for the most heat-intensive operating regime of the receiver tank block, in which four tanks are cold and operate in the product desublimation mode, two tanks are being cooled after the evaporation of the product, and six tanks are reserved, being maintained in the cooled state. Experimental data are presented for the cooling of the vapor desublimation tank section using the VKhM- 0.54/0.6 air cooler. The mathematical model of the gas dynamic processes of cold air flow in the pipeline and tank walls–air heat transfer is used to calculate the cooling of the six tanks with a cold air stream from the VKhM-0.54/0.6 cooler. A good quantitative fit between the calculated data and experimental measurements has been attained. The performance parameters of the VKhM-0.54/0.6 air cooler can ensure uranium hexafluoride recovery from the gas mixtures arriving from the collector of the condensation–evaporation apparatus and purification of the product.

The purification of niobium from antimony impurity via extraction with tributyl phosphate from solutions of the HF + NH₄F mixture has been studied. It has been established that at an HF + NH₄F content equal to 7–16 mol/L and an NH₄F concentration of 30% in the mixture, Sb extraction hardly changes (70–80% for one stage), and Nb coextraction abruptly decreases to values of less than 0.5%.

As a solar cell a heterostructure has been proposed that consists of an anode copper oxide Cu₂O and a transparent conductive layer Cd–Sn–O obtained via extraction-pyrolytic method. The heterostructure is formed on a copper substrate by means of anodic oxidation with further applying a transparent conductive oxide film. An increase in the efficiency of the Cu₂O/Cd–Sn–O element compared with Cu–Cu₂O structure has been shown to be possible.

It has been shown that an electric spark discharge in saturated alkaline solution acts as a catalyst of ionization during the decomposition of kaolinite into aluminate and silicate components. The production of aluminum hydroxide from KM-1-grad kaolin (Chalgansk deposit) is 24.8–37.2% of the estimated value.

The ability to acquire thermal control coatings of the “solar reflector” and “true absorber” class modified with iron oxide nanoparticles has been studied. The optical and adhesive properties of thermal control coatings have also been established.

The regularities of intermolecular and chemical interactions of aramid fibers and the epoxide matrix have been studied. The strength of the composite interface has been shown to be determined by the fiber–matrix joint.

An increase in abrasive resistance of metal-ceramic membranes with substrates made of steel 316LF and titanium and TiO₂-based and ZrO₂-based selective layers has been described. The role of oxidizing additives (K₂Cr₂O₇ and Na₂MoO₄) in sintering of ceramic layers has been shown. The attrition resistance and structural characteristics of composite membranes have been described.

The paper discusses the effects of ultra-high frequency radiation and constant and variable magnetic fields on the structural mechanical properties of heavy oil from the Yarega oilfield. It has been found that a constant magnetic field reduces the viscosity of the oil by almost two times, and microwave radiation promotes the formation of insoluble structures.

The possibility of preparing cobalt(II) salts from cobalt chloride solutions via extractive conversion has been demonstrated. Di-2-ethylhexylphosphoric, caprylic, and bis(2,4,4-trimethylpenthyl)phosphonic acids and trioctylamine have been tested as extractive agents. The results of large-scale laboratory tests of techniques for the extractive conversion of cobalt chloride into cobalt sulfate are provided.

The possibility to prepare metal ceramics based on carbides and titanium carbonitrides from intermetal alloy scrap has been studied. The influence of sintering conditions on phase and structure formation processes in a metal ceramics material and on the composition and properties of the prepared material has been analyzed.

A method for recovering some rare-earth oxides (Dy₂O₃, Y₂O₃, and Pr₆O₁₁) with their simultaneous purification via the breakdown of aluminosilicate sludges by soda has been proposed using an example of model samples that contain these oxides sintered with 11 admixture oxides. The developed process has been shown to be efficient for the recovery of rare-earth oxides of chemically pure grade from chemically complicated sinters.

A method for the online control of cerium extraction from rare-earth raw materials based on the oxidation of its trivalent ions with hydrogen peroxide, followed by the precipitation of hydroxide and additional acid treatment to remove trivalent impurities has been considered.

The desorption of rhenium from an A172 anion exchanger with an ammonia solution has been studied. A172 and A170 anion exchangers have been investigated with infrared spectroscopy. The difference in their structures has been revealed so that A172 can be assigned to a medium basic anion exchanger type. The reason for the low desorption of rhenium from the A172 anion exchanger has been determined.

The mechanism of uranium tetrafluoride formation during the reduction of depleted uranium hexafluoride in hydrogen fluoride flame has been studied. Based on the performed studies, it has been established that powder uranium tetrafluoride with characteristics that enable it to be used for both long-term storage (minimum specific surface area, 0.6 ± 0.1 m²/g; untapped density, 2.7 g/cm³) and metallic uranium production (maximum specific surface area, 1.45 m²/g) can be obtained by adjusting the operational regime of a flame reactor.

Two possibilities have been considered for improving the operation of a cascade of mixer-settler extractors, i.e., a new connection scheme between process vessels and a new chromatographic mode for carrying out the process. Studies on cobalt and nickel separation have been performed using an experimental setup and technological solutions taken from cobalt production with Cyanex extractants. A comparison of results obtained using the experimental setup with the data of an production plant operation has shown that the new scheme results in a marked increase in the productivity and efficiency of metal separation in a cascade of mixer-settler extractors. Based on numerical studies, it has been found that the cyclic process in the chromatographic mode allows one to separate a multicomponent mixture using a single operation.