卷 52, 编号 4 (2018)

An analytical review of achievements in the field of the design of industrial equipment for mixing liquids, suspensions, and gas–liquid dispersions is presented. Various methods of mixing are discussed: mechanical, pneumatic, jet, vibrational, and magnetic. Nonconventional mixing devices with reversible movement of mixer parts, as well as static, rotary, rotor-stator, vortex, and ultrasonic devices, are considered. Miniaturization of equipment and micromixers were also reviewed.

Mathematical models of electrochemical processes in reactors with flow-through 3D electrodes for the electrodeposition of metals from a polycomponent electrolyte solution have been presented. The parameters of the process and electrode, such as the flow rate of the electrolyte, porosity, specific surface, and the specific conductivity of the electrode and solution, at each electrode point during electrolysis have been taken into account. The mathematical models and methods for determining the electrochemical and hydrodynamic parameters of multicomponent electrochemical systems have been described. The data have been used to calculate industrial electrochemical processes in flow-through 3D electrodes. The adequacy of these methods has been shown. The experimental and calculated data on the electrodeposition of gold and silver from sulfuric acid thiourea solutions to carbon-graphite fiber cathodes have been analyzed. The dependences of electrodeposition parameters on the electrolysis conditions, the initial properties of the electrode-solution system, and the concentration ratio of gold and silver in the solution taking into account the joint reduction of hydrogen ions and molecular oxygen have been examined. The current and resulting regularities of the processes have been revealed. The adequacy of the mathematical models for industrial joint electrodeposition of gold and silver from sulfuric acid thiourea solutions on flow-through 3D electrodes taking into account the side electrode reactions has been shown. The appearance of anode zones on a cathode polarized carbon fiber flow electrode during the deposition of metals from multicomponent systems has been considered.

The flow of a viscoplastic fluid during the filling of a flat vertical channel was studied. The mathematical problem was formulated based on the complete equations of motion and natural boundary conditions on a free surface; the problem was solved by the finite-difference method. For shock-capturing, the Schwedoff–Bingham rheological equation was regularized. A parametric study of the flow characteristics and behavior of the free boundary was performed depending on the main parameters of the problem. The characteristic flow structures were demonstrated depending on the ratio of viscous, gravitational, and plastic forces in the flow.

The peculiarities of the sedimentation of aggregates in a bidisperse (or two-fraction) suspension have been studied. A complete set of equations for the dynamics of an aggregate and suspension in the presence of the interfractional coagulation process and the hindering effect has been given. For the marginal Stokes and Newtonian regimes (corresponding to small and large Reynolds numbers), formulas have been obtained for the stationary sedimentation rate of aggregates, and their analysis has been performed. Some results of the numerical integration of the equations of motion of large particles in a suspension are have been. It has been established that the coagulation leads to an increase in the sedimentation rate of an aggregate and, on the contrary, the hindrance contributes to a decrease in the sedimentation rate. The nonmonotonic behavior of the sedimentation rate of aggregates as a function of the volume fraction of the dispersed phase is found.

The principles of suspension dewatering using drainage on belt press filters are considered. A relationship describing the dependence of hydrostatic pressure, which is the driving force of the process, on time and the initial conditions, is proposed and experimentally confirmed. The equations for the calculation of the belt speed depending on the load on solids and for the solution of the reciprocal problem, which is represented by the determination of the capacity of the filter in solids at various belt speeds, are derived based on this. The calculated data, which were obtained from the results of laboratory studies on dewatering using the drainage of model suspensions, indicate that the capacity in solids at the belt speed of 0.35 m/s is 6.8–15.7 t/h. These data do not contradict the results of the pilot-scale tests.

The experimental study of polymer degradation processes in a solution is carried out. A mathematical description of the time dependences of the main polymer structural characteristics, i.e., the number average M_w and the weight average M_n molecular weight and the polydispersity coefficient K_p are obtained. For the model adequacy to be tested and the calculation error to be estimated, linear polymers—SKD-ND rubbers— are used as experimental samples. The change in the polymer molecular weight distribution (MWD) and its parameters are studied by gel permeation chromatography. The resulting dependences can be used for the process control systems. The developed mathematical description relates the controllable and control parameters in the structure (initial reagent concentrations, the reagent ratio, reaction temperature, etc.). However, the complete reconstruction of the mode of the MWD and its time dependence cannot be achieved.

Sorption properties of synthetic nanostructured potassium aluminosilicates with Si/Al ratios from 1 to 5 fabricated in a multicomponent system KOH–Al₂(SO₄)₃·18H₂O–SiO₂·nH₂O–H₂O under static sorption conditions at various temperatures and nitrate salt background have been investigated; the activation energy of cesium ions sorption has been evaluated.

Prospects of applying the extraction-pyrolysis method to fabricate complex oxide composites, including nanoscaled ones, based on rare-earth elements, iron, magnesium, bismuth, zirconium, tantalum, niobium, platinum, and other elements bearing practically significant functional properties—magnetic, optical, and catalytical—are investigated. The composition, morphology, and properties of the synthesized functional materials are examined.

The process of obtaining silicon dioxide upon the interaction of fluorosilicic acid with an aqueous solution of ammonia is studied. The fluorine-containing compounds in synthesized dioxide are identified by ¹⁹F NMR spectroscopy. It is shown that the two-stage method of precipitation followed by washing, allows producing silicon dioxide with a fluorine content of units of ppm.

The results of the synthesis of tungsten carbide from the oxide phase of scheelite concentrate are given. It is shown that the reduction and carbonization of tungsten occur upon exposure of the concentrate to high energy densities, provided that a protective atmosphere and a reducing agent are present.

A combined procedure of zinc peroxide granulation and encapsulation in one technological stage has been developed, which ensures the stabilization of ZnO₂ by forming a coating on the surface of the product granules. It is shown that the use of sodium polyphosphate in a combined process of granulation and encapsulation as encapsulating agents with the concentration in the initial solution of 1% allows obtaining a capsular product, which is significantly more resistant to the action of wet carbon dioxide than a nonencapsulated analogue.

The results of an experimental study of separating and concentrating the components of liquid mixtures by a non-steady-state extraction–chromatography process in the countercurrent cyclic mode have been presented. An acceptable agreement between predictions by the theory of the process and the results of experiments has been found.

The results of producing cellulose from oat straw and husk using the hydrotropic method are presented. It is shown that the cellulose samples from oat straw and husk demonstrate similar main characteristics. The samples of cellulose nitrates are synthesized under conditions for the production of colloxilines, which are similar to lacquer colloxilines in their main characteristics. The production of cellulose from oat straw and husk and nitrates based on it is confirmed using methods of IR spectroscopy.

The process of the hydrotropic delignification of oat straw in the universal thermobaric unit has been investigated. The effect of the main regime parameters of cooking is considered and the experimental–statistical model is constructed predicting the change in lignin mass content in the treated material. The optimal conditions for the cooking process that ensure the minimal residual amount of lignin in the cellulose are determined.

In construction there is increased interest in using basalt fibers as an alternative to traditional polymer composite materials based on glass, organic fibers, or carbon fibers. In this respect, new information revealing the possibilities of basalt plastic materials as construction materials is of interest. In this paper, the influence of the type of filler on the physical and mechanical properties of basalt-textolite and fiberglass is studied. A description of composites based on basalt fiber and fiberglass and the production of basalt continuous fiber is given.

The catalytic activity of transition metal compounds (Mo, V, and W) in the reaction of oxidative desulfurization of straight-run diesel fuel with hydrogen peroxide is studied. Oxidation with sodium molybdate decreases the total amount of sulfur in straight-run diesel by 43%, whereas the total amount of C₂₀–C₃₁ hydrocarbons is reduced from 87.4 to 83.6%.

The prospects for extracting finely dispersed gold and other useful components from the magnetic tailings of gold recovery plants and other sources are shown. This is achieved by using the process of leaching these particles and their extraction by sorption on metastable nanocrystalline water structures. A gold simulator, a colloid of molecular copper, is passed through the sorbent of a metastable nanocrystalline water structure. After three passes through the sorbent, the copper appears to be completely sorbed. Thus, according to the qualitative analysis of copper sorption, the possibility of extracting gold using this technology is confirmed.

The preparation of inorganic brown pigment from red mud is investigated. The results of the phase and chemical analyses of raw material and the product are given. A flow diagram is proposed and the parameters of the pigment production are recommended. This approach has provided a pigment of pure color with the opacity of 8 to 10 g m^–2 from red mud (up to 80%) without additives and the reduction of Fe(III) into Fe(II) using sulfide sulfur.

The results of testing the efficiency of the process of filtering zinc melt obtained after dissolving the fuel rod cladding from the BOR-60 reactor with SNF nitride in a laboratory installation for zinc melt purification from suspended fission products, intermetallic compounds, and fuel particles in the conditions of the protective chamber are presented. The feasibility of filtering for zinc recovery after dissolution of the fuel rod cladding is demonstrated, while considering the ratio of structural materials and zinc corresponding to the tests performed.

The results of an investigation dealing with pure ammonium perrhenate synthesis from crude ammonium perrhenate by multi-stage recrystallization are presented. It is shown that it is impossible to produce ammonium perrhenate of the AP-00 grade with the permissible potassium impurity level using this method. Recommendations for synthesis of the salt of the AP-0 grade are given.

We compared the heat consumption in the separation of binary mixtures by distillation (single evaporation) and rectification for mixtures with different levels of separation by distillation. The advantage of rectification over distillation was shown. The direct dependence of the internal energy saving in rectification on the minimum reflux ratio was established.

In this paper, we compare various estimates of the abilities of liquid mixtures to be separated by distillation. The minimum specific heat consumption in rectification is shown to be proportional to the fraction of the upper product and the minimum reflux ratio. The conditions for energetically favorable application of different schemes of separation of three-component mixtures are determined. We also calculated the minimum reflux number for real binary mixtures with the possibility of forming pinch regimes. In the presence of a pinch mode in the strengthening part of the column, the value of the minimum reflux ratio is proved to be independent of the aggregate state of the initial mixture. For this case, we derived a formula for calculating the minimum reflux ratio taking the energy level of the initial mixture into account.

A low-concentration nitrogen oxide recovery unit with a capacity of 50 m³/h equipped with γ-Al₂O₃ granules saturated with a water solution of carbamide and ammonium bicarbonate has been developed, produced, and tested. During the tests, the unit operated for approximately 176 h; it maintained capture efficiency at a level of 90 to 95% for 156 h. The unit captured 3.6 kg of nitrogen dioxide during its operation period.