Phase equilibria in sections of the MgCl2–MgCl2⋅CO(NH2)2⋅4H2O–H2O system at temperatures from 0 to –37.5°C were studied, and a preliminary assessment of the feasibility of using the compound MgCl2⋅CO(NH2)2⋅4H2O for the development of deicing reagents based on it was given.
Ceramic pigments with a wollastonite structure were synthesized using natural quartz sand and limestone. At 1300°C and a firing time of 1 h, α-wollastonite forms in samples containing 5–10
The effect of calcined diatomite from the Dzhradzor deposit in Armenia on the strength and hydration processes of Portland cement has been determined. Calcined diatomite intensifies cement hydration and contributes to strengthening of cement-based compositions. The material containing 2 wt
A low-temperature extraction–pyrolytic method is proposed for the synthesis of phosphors based on rare-earth phosphates: LnPO4 (where Ln = Eu, Eu + Y, Tb, Tb + Gd, and Tb + Nd), Eu3PO7, Eu(PO3)3, Eu(PO3)3:Eu2+, Tb(PO3)3, La1–хTbхP3O9 (х = 0.05, 0.10, 0.20, 0.30, and 0.40), La0.8Ce0.15Tb0.05PO4, La0.8Ce0.15Tb0.05(PO3), NaY1–хEuxP2O7, and NaY1–хTbxP2O7 (х = 0, 0.025, 0.05, 0.075, and 0.1). The compounds are characterized by X-ray powder diffraction analysis and IR and luminescence spectroscopy. A comparative analysis is made of the spectral and luminescence characteristics of the Eu3+ and Tb3+ ions in simple and doped phosphate phosphors. It is shown that the luminescence intensity of Eu3+ and Tb3+ in phosphates increases in the presence of activator ions.
Experimental data on extraction and separation of rare earth elements (REEs) from technological chloride solutions obtained by leaching carbonates of these metals with 10 M HCl are presented using solutions of mixtures of extractants P507 and Cyanex 272 (1 : 1). The mixture of extractants P507 and Cyanex 272 in the initial acidic and sodium forms is shown to be a promising extraction system for separation of yttrium from the total REEs with subsequent separation of terbium and dysprosium fractions from the remaining REEs during processing of solutions obtained by leaching carbonates of rare earth elements.
Optimal conditions for the preparation of yttrium stannate with a pyrochlore structure by hydrothermal synthesis were determined. A preliminary assessment of the feasibility of using this method is presented.
The article provides a review of pyrolysis processes, including the stages of pyrolytic decomposition of organic substances according to temperature ranges. Six categories are considered depending on operating conditions: slow pyrolysis, fast pyrolysis, flash pyrolysis, vacuum pyrolysis, intermediate pyrolysis, and hydropyrolysis. Methods for treating gaseous emissions are examined, such as: gas recirculation; absorption of gases into liquids; adsorption of gases onto solid materials; passing the gas through a hot flame; detonation-mode disposal of pyrolysis gases; and dispersion of industrial emission components in the atmosphere to harmless concentrations.
Presented and discussed are the equipment and process design solutions developed for Gazprom Neft for the main functional units of reactor-regenerator sections of fluid catalytic cracking (FCC) units with controlled process severity. These solutions enable both the revamp of existing FCC units and the construction of new, state‑of‑the‑art facilities designed for flexible operation across various cracking modes: from the conventional fuel‑oriented mode to the petrochemical mode of the process.
A domestically developed and patented technology for controlled fluid catalytic cracking (FCC) process, employing proprietary bi-zeolite catalysts, is presented. It enables the creation of versatile catalytic cracking units suitable for operation either in the conventional fuel-oriented mode, maximizing the yield of high-octane components of commercial gasoline, or in a petrochemical mode with an increased yield of light olefins, in particular propylene, which is a key feedstock for petrochemical production. The features of the process technology are discussed, including the means of product yield distribution control and appropriate equipment layout of the reactor–regenerator unit for such installations.
This paper examines the use of open-loop heat pumps in the separation of binary heteroazeotropic mixtures by distillation. Schematic diagrams of installations with various material and heat flow arrangements are provided. The energy costs required for the proposed separation options are estimated. It is shown that the use of heat pumps can significantly improve the energy efficiency of separating the mixtures in question.
Due to the specific features of horizontal wells, the methods used in vertical and deviated wells to increase oil recovery, including chemical methods, are either economically inefficient or inapplicable. The application of ultrasonic vibrations makes it possible to intensify and accelerate a number of chemical reactions, so the development of a method to enhance oil recovery based on combining chemical methods of increasing oil recovery and ultrasonic intensification should increase the efficiency of horizontal wells. However, this method requires the development of a downhole/submersible ultrasonic transducer for aggressive environments. The corrosion resistance of stainless steel and titanium samples under the influence of ultrasonic vibrations was investigated. It was found that using VT1‑0 grade titanium as the structural material for the submersible transducer allows achieving the lowest corrosion rates even under the most aggressive conditions in the presence of a titanium corrosion inhibitor; however, other components of oilfield equipment that cannot be made from this material are subjected to increased corrosion stress. Based on the results obtained, stainless steel is recommended as the material for manufacturing the submersible transducer instead of titanium and a titanium corrosion inhibitor.
For the first time, the possibility of using the sorption of metal cations from an aqueous solution by a porous carbon material with subsequent introduction as a doping additive for obtaining an ultraviolet pigment during reductive heat treatment of phosphogypsum was studied. The revealed patterns open wide possibilities for involving wastes, wastewater from industrial enterprises and solid wastes of chemical production, in secondary recycling with the production of domestic products with high added value.
In this paper, stonecast matrices (SCM) synthesized by melting together basalt and U-containing Al2O3 were studied. The modification of Al2O3 precursors containing 10 wt
New composite construction materials for various applications have been developed, including thermal insulation, structural–thermal insulation, and facing materials. Waste from aluminosilicate rocks, including tuffs, perlites, zeolites, basalts, and slags, was used as raw material. The physicochemical and mechanical properties of the raw materials and the resulting materials were studied. The competitiveness of the materials was enhanced by microwave thermal treatment.
Melting and crystallization processes of the Si–Al–Ti–Fe–Mg–Ca–Na–K–O system, representing picrobasalt, an ultrabasic volcanic rock of subalkaline type with 35
A new approach to the destructive processing of finely disperse ion-exchange resin KU-2x8-M (M—Ni, Cu, Nd, Fe, U) on the basis of gas-phase treatment in a nitriding atmosphere with further chemical processing of conversion products is considered. It is shown that the exposure of finely disperse ion-exchange resin KU-2x8-M samples (M = Ni, Cu, Nd, Fe, U) to an HNO3 (vapor)–air atmosphere at temperatures of 130 and 150°C for 24 h with further dissolution of conversion products in 0.5 mol/L NaOH and ozonation of resulting solutions provides the efficient utilization of finely disperse ion-exchange resin KU-2x8-M.
The article considers and analyzes typical designs of tubular (shell-and-tube and tube-in-tube) heat exchangers used in industry. Based on the identified shortcomings of typical designs in terms of specific performance indicators of heat exchangers, general promising directions for their improvement are formulated.
Processes for hydrometallurgical treatment of molybdenum concentrate by leaching with a 30
Pyrolysis of the ion-exchange resin KU-2–8-H+ under irradiation in a microwave field at a power of 600–800 W and irradiation time of 2–30 min was studied. Pyrolysis produces spherical granules consisting of an ion-exchange resin core and a carbon shell. The synthesized pyrolysis granules were characterized by X‑ray diffraction and thermogravimetric analyses; IR spectra were recorded, physical adsorption characteristics were determined, and water saturation data were obtained.
