S. K. Myasnikov

Extraction of bitumen, crude oil and its products from tar sand and contaminated sandy soil under effect of ultrasound.

In the present paper, the kinetics of the water extraction of bitumen from tar sand and crude oil or residual fuel oil from model contaminated soils under the effect of ultrasound is studied. The influence of process temperature, ultrasound power, the nature, and properties of the components of heterogeneous mixtures being separated, and the concentration of added alkaline reagents on the rate and degree of oil recovery is investigated. A functional form of the dependencies of separation efficiency on the mean size of solid particles and the temperature of a working medium is found. Optimum concentrations of reagents in the process solution are determined. It is shown that the spent solution of sodium silicate can be multiply used for separation, its reuse even speeding up the yield of oil in the initial period. Taking into account obtained results, a multipurpose pilot plant with a flow-type reactor for ultrasonic extraction of petroleum and its products from contaminated soils was manufactured and tested. During tests, the purification of sandy soil contaminated with residual fuel oil was carried out which verified the results of laboratory studies.

Transport of Impurities out of a Two-Phase Crystal Layer into a Melt under the Effect of a Temperature Gradient: Mechanisms and Kinetics

Possible mechanisms and kinetics of removal of eutectic-forming impurities from a two-phase crystal layers with a transverse temperature gradient are considered. Mathematical models are suggested for various mechanisms of impurity transport out of a crystal layer into the surrounding melt. Equations for estimating the purification rate of layers with open and closed pores are derived and analyzed. These equations are intercompared and are checked against the results of numerical solution. It is shown that, in the case of the migration of closed inclusions, the purification rate is higher than in the case of the diffusion of impurities out of open pores.

Kinetics, energy characteristics, and intensification of crystallization processes in chemical precipitation of hardness ions

An analysis of the literature data on the solubility and kinetics of the chemical (reagent) precipitation of calcium carbonate and magnesium hydroxide is performed. The possible causes of the significant discrepancy in the available data are considered. The kinetics of the homogeneous and heterogeneous crystallization of calcium carbonate and magnesium hydroxide in reagent precipitation is studied using different methods. It is shown that the use of heterogeneous crystallization on seed particles pretreated in an ultrasonic field raises the rate of crystallization by an order of magnitude. The kinetics of nucleation is studied; the effect of supersaturation and temperature on the induction period in the homogeneous and heterogeneous nucleation of CaCO3 and Mg(OH)2 crystals is investigated. The energy characteristics of nucleation, namely, the interfacial tension (surface energy) and activation energy, are determined. The use of fine-dispersed particles activated by ultrasound makes it possible to considerably reduce the energy barrier for nucleation.

Kinetics of Crystallization of Binary Melts of Eutectic-Forming Substances

The crystal nucleation and growth rates in eutectic-forming melts are experimentally determined using a universal technique for finding the kinetic parameters of processes involving phase transformations. It is shown that, with an increase in the concentration of the impurity component, the crystal nucleation and growth rates gradually decrease and reach a minimum at a eutectic point. It is confirmed that inter- and extrapolation equations known in the theory of crystallization of one-component melts can be used to obtain reliable values of the kinetic parameters in the crystallization of binary melts at large supercoolings.

Ultrasonic technologies for extracting oil products from oil-bearing sands and contaminated soils

The kinetics of the extraction of oil products (bitumen, oil, and fuel oil) from natural and model oil-bearing sands after ultrasonic treatment was studied. The effects of the process temperature, the nature and properties of the separated components, and the concentrations of the added reagents on the rate and extent of oil product extraction were also studied. The functional form of the dependences of the separation efficiency on the mean size of the solid particles and the working medium temperature was determined. The working solution of sodium silicate can be recycled in the separation, and its reuse can even accelerate the extraction of oil products at the first stage. Based on the obtained data, we created and tested a universal pilot apparatus for ultrasonic oil extraction from oil-bearing sands and the purification of soils contaminated with oil products.

Hybrid separation processes combining vacuum distillation with fractional crystallization, partial melting, and granulation

The physicochemical fundamentals of the combined processes of distillative crystallization (also called distillation crystallization or distillative freezing) and distillative sweating (also called distillation sweating or distillation melting) are considered. Results of the experimental study of the kinetics of separation of binary and ternary organic mixtures of various forms (liquids, powders, continuous layers, and granules) are presented. The high efficiency of the combined processes that make it possible to rapidly decrease the impurity content by one to two orders of magnitude after a single stage is shown. It is found that these processes can be used for effective separation of the mixtures of a eutectic composition when conventional crystallization is not applicable. Dependences of the important kinetic characteristic—an effective diffusion coefficient—on pressure are determined for a number of mixtures. An empirical formula for estimating its values is proposed. It is found that the kinetic features of the combined processes conducted under nonequilibrium conditions can cause both a decrease and an increase in the efficiency of separation of the mixtures of different types in comparison with calculated values for the equilibrium process. A method is developed that makes it possible to combine distillative crystallization with the granulation of a melt in a semicontinuous or continuous process on a cooled movable belt. The method ensures the additional purification of solidifying granules from volatile impurities. Results of calculating the main characteristics of the combined process for purifying naphthalene granules in the batch and continuous modes are given.

Countercurrent column crystallization of ternary mixtures with different mutual solubilities of components in the solid state

Characteristic features of the mass transfer in separation of ternary organic mixtures of two types and different compositions in a countercurrent crystallization column are studied. In a mixture of the first type, all the components form continuous series of solid solutions of each other, and in mixtures of the second type, only one pair of components does. The temperature and concentration distributions along the height of a modernized column in the startup period and steady-state operation are experimentally investigated. It is found that the concentration profile of the component with an intermediate melting point in the separation of a mixture of the first type has an extremum. Mixtures of the second type behave as pseudobinary mixtures if the crystallization occurs in the field of the component that forms simple eutectics with the two other components. The results of separation of ternary and binary mixtures of the same components are compared. It is shown that it is possible to increase the efficiency of separation of binary mixtures with solid solutions by controlled introduction of a third component.

Melt Entrapment and the Effective Distribution Coefficient during the Growth of a Crystal Layer

Methods for calculating the separation efficiency during the growth of a crystal layer from a binary melt are considered. It is shown that the amount of the mother liquor entrapped by a broken crystallization front and the effective distribution coefficient are determined by the ratio of actual and equilibrium temperature gradients near the surface of the growing layer. Theoretical results are in fair agreement with experimental data.

Removing Volatile Impurities from Granules by Distillation Sweating

The physicochemical foundations of distillation sweating and the kinetics of the removal of volatile impurities from granules are considered. Expressions are suggested for estimating the separation efficiency in this combined process. Diphenyl, naphthalene and caprolactam granules have been purified. The influence of the nature of the separated components, the process conditions, and scale factors on the rate and efficiency are examined. The advantages of distillation sweating over ordinary distillation, sublimation, and fractional melting are demonstrated.

Modeling the separation of oil sand

Mathematical modeling of ultrasonic or mechanical separation of oil sand in an aqueous alkaline medium was performed. Kinetic dependences were obtained that adequately describe bitumen recovery based on the limiting role of chemical transformations or mass transfer. It was shown that the second model describes the process kinetics better. A comparison of the theoretical and experimental data allowed us to obtain empirical equations that relate the kinetic coefficients of the model to the characteristics of the heterogeneous mixture being separated and the main process parameters. Recommendations on the technological conditions of separation were given.