Theoretical Foundations of Chemical Engineering最新文献

The article is devoted to improving the separation technology of the methanol + water + methyl methacrylate mixture. Several alternative variants are proposed: separations based on the application of auto-extractive distillation and a combination of distillation and splitting process. The separation schemes are aimed at separating all components in pure form and increasing the yield of methyl methacrylate. A computational experiment is carried out to determine the operating parameters of the columns to ensure the production of substances of a given quality. The most energy-efficient scheme is based on the use of auto-extractive distillation and a combination of distillation with splitting process.

A study was made of the ability of crown ethers in heavy polar organic diluents (chloroform; 1,2‑dichloroethane; bis(2-chloroethyl) ether; 1,1,7-trihydrododecafluoroheptyl alcohol) to extract cesium and strontium from nitrate solutions. It was shown that the use of bis(2-chloroethyl) ether as a polar diluent in the extraction with dibenzo-21-crown-7 and 4,4'(5')di-tert-butyldibenzo-18-crown-6 leads to sufficiently high distribution coefficients D_Cs of cesium from solutions with a nitric acid concentration of 1–5 mol/dm³. When extracting strontium with dicyclohexyl-18-crown-6, the highest distribution coefficients D_Sr were achieved using chlorine-substituted hydrocarbons and bis(2-chloroethyl) ether with a maximum extraction of 1–3 mol/dm³ HNO₃, depending on the diluent used. Extraction systems based on selective crown ethers in a mixture of solvents were proposed for the co-extraction of cesium and strontium from nitric acid solutions of complex chemical compositions.

Studies on the extraction recovery of Fe(III), Co(II), Cu(II), and Zn(II) impurities with individual extragents and tertiary amine mixtures from nickel chloride–sulfate solutions are carried out. Using cobalt(II) extraction as an example, the effect of the modifier type, extragent concentration, and dilutant nature on the extraction of impurities is established. A process layout for the purification of nickel solutions from impurities is developed.

Abstract—A series of studies on the use of acridine salt latex systems to reduce aggregative stability is presented. It is shown that the use of this salt makes it possible to achieve complete recovery of rubber from latex at a consumption of 2.0–2.5 kg per ton of rubber. It is found that the temperature of the latex coagulation process does not affect the coagulant consumption. The main indicators of the resulting rubbers and vulcanizates correspond to the normative ones.

The use of composite cements consisting of calcium aluminate and calcium sulfate for solidification of aqueous NaNO₃ concentrates (liquid radioactive waste imitators) is considered. Matrices that meet the requirements to cemented solid radioactive waste were obtained. The effects of the composition of the formulation on the properties of the matrix were studied.

Algorithms and results of the design and verification versions of calculating chemical technology apparatuses are compared. It is shown that the verification version of the calculation is not appropriate for the correct selection of technological equipment when organizing chemical production. On the example of separating liquid mixtures by rectification, it is shown that the large number of specified initial calculation parameters leads to a discrepancy in the material balance and the required purity of the products obtained from the separation process. An algorithm for the design calculation of a rectification unit for separating three-component liquid mixtures is proposed. It is noted that it is necessary to maintain material balances not only in the first column but throughout the entire unit.

It is established that acid-resistant tiles satisfying GOST (State Standard) requirements cannot be manufactured from unenriched kaolin clay containing less than 18% of Al₂O₃ even at a firing temperature of 1300°C. The addition of an optimal grog quantity (40%) to the ceramic mass makes it possible to manufacture acid-resistant tiles corresponding to GOST requirements at a firing temperature of 1300°C. The use of ferrochrome production slag with an increased content of alumina (Al₂O₃ > 50%), magnesia (MgO > 15%), chromia (Cr₂O₃ > 5%), and calcia (CaO > 12%) enables the manufacturing of products with high technical characteristics within a firing temperature range of 1250–1300°C. X-ray diffraction analysis shows that the introduction of ferrochrome production slags into ceramic masses promotes the appearance of new minerals in the X-ray diffraction pattern, such as magnesium chromite (MgCr₂O₄), chromite (FeCr₂O₄), forsterite (Mg₂SiO₄) and magnesia aluminum spinel (MgAl₂O₄), corundum (Аl₂О₃), bonite (CaO⋅6Al₂O₃), and chromia (Cr₂O₃), which substantially improve the technical characteristics of acid-resistant materials. The presence of the above-mentioned minerals in the samples is also confirmed by IR spectra. A Russian Federation Patent for the use of ferrochrome production slag has been obtained.

Abstract—The processes of processing copper sulfide concentrate by roasting it with caustic soda without air access with the extraction of the main components (copper, iron, sulfur) were studied. After leaching and filtration of the sinter, sulfur is released into the filtrate in the form of Na₂S. At the same time, the release of sulfur dioxide gases into the atmosphere is completely eliminated.

The results of experimental studies on the decomposition of a waste catalyst containing a precious metal (palladium) in the surface layer by the acidic method are presented. Two approaches implying complete dissolution of the catalyst, including its support, and selective palladium extraction (with minimum dissolution of the catalyst support) are considered. The optimal decomposition conditions providing extraction of at least 90% of the palladium into the solution are selected.

The aim of this work is to develop a mathematical model of the dihydrate–semihydrate process (DSP), the process of obtaining wet process phosphoric acid (WPPA) under continuous conditions. A technological scheme for the production of WPPA for industrial conditions is proposed. Using mathematical modeling, the consumption of sulfuric and phosphoric acids, as well as the volume of phosphorite feed, are refined. The working volumes of the equipment for the first and second stages of the process are selected. Recommendations are developed for the use of this method in industry.