A method for processing perlite with a 20% caustic soda solution at a temperature of 108°C was developed. The work was aimed at studying the processing of perlite at low temperatures, without autoclaving, without sintering, and with the extraction of a significant amount of useful components: aluminum oxide and silicon oxide with the production of sodium metasilicate nanohydrate, aluminosilicates of various metals, and crystalline SiO2.
A method for synthesizing magnetic polymer microspheres with carboxyl groups on the surface is proposed. In an aqueous medium, magnetic microspheres form stable colloidal dispersions with an average hydrodynamic particle diameter of 110–170 nm and a negative surface charge. When dispersed in an aqueous–organic mixture, the microspheres remain resistant to aggregation. Microspheres can be extracted from the dispersion using an external magnetic field. Magnetic microspheres can be used as supports for heterogeneous catalysts operating in organic media.
The behavior of actinium-227 and actinium-228 in the life cycle of monazite processing is considered. The recommended system for separation of actinium-227 and actinium-228 is 90–100% TBP–300–350 g/dm3 of Ln(NO3)3–0.1–0.5 mol/dm3 of HNO3. The process is combined: actinium-227 and actinium-228 are removed simultaneously with purification from rare earth impurities, iron, aluminum, calcium, and phosphate ions occurs. If monazite does not contain uranium, it is recommended to hold the rare earth concentrate (solution or carbonates) after separation of thorium for 1–2 days. A process flow chart for separation of the sum of REEs isolated from monazite is proposed, with production of didymium, lanthanum–cerium concentrate, and yttrium REE concentrate.
The dissolution of quartz during the hydrometallurgical desilication of silica–titanium concentrates from Pizhemskoe field (Komi Republic) was studied. The concentrate desilication occurs in the CaO–SiO2–Na2O–H2O system due to the binding of silica into calcium silicate hydrate, in particular, into CaO·SiO2·nH2O. The main factors (temperature, duration, CaO : SiO2 ratio, NaOH content) governing the extent of concentrate desilication and crystallization of wollastonite from calcium silicate hydrates resulting from the reaction were determined.
It was shown that bismuth subsalicylate BiC7H5O4 of high purity (with low contents of impurity metals and nitrate ions) is advisable to obtain from bismuth subnitrate [Bi6O5(OH)3](NO3)5⋅3H2O through converting it into oxide Bi2O3 by treating with a solution of sodium hydroxide and then into bismuth subsalicylate BiC7H5O4 by treating bismuth oxide with a lactic acid–salicylic acid solution at a temperature of 60–85°C.
A complex electrochemical technology for treating wastewater from a meat processing plant is described. During the water treatment process, sequential treatment occurs in an electrochemical module with a graphite anode and an electrochemical module with an iron anode, as well as holding in a maturation and averaging chamber. It has been proven that in the module with an iron anode, ferrates are generated, which simultaneously perform the functions of a soft oxidizer, coagulant, and steel corrosion inhibitor.
The review shows the relevance and advantages of application of controlled-release fertilizers and describes their production methods and practical implementations. A classification method developed by the authors is proposed, and the main properties and quality control indicators for such fertilizer products are determined.
Using the method of thermochemical activation of wood-processing waste in H3PO4 at 1173 K, a microporous carbon adsorbent EC-103 (1) is obtained with a specific micropore volume of W0 = 0.80 cm3/g, a micropore width of X0 = 1.32 nm, and a specific surface area of SBET = 2115 m2/g. At 303 K and 20 MPa, the adsorption activity of the adsorbent reaches ~22 wt % for methane. The volumetric density of adsorbed methane on the compacted adsorbent EC-103 (1) with a binder at a pressure of 10 MPa reaches ~200 nm3/m3.
The results of studies on the inhibition of uncontrolled side reactions during the synthesis of epoxyacrylate oligomer from epoxydiane resin ED-20 and acrylic acid are presented. The factors governing the esterification of ED-20 with acrylic acid were studied. The efficiency of using p-methoxyphenol as an inhibitor of side reactions during the synthesis of epoxyacrylate oligomer was examined, and its optimum amount was determined.
A review was made of the literature data published in Russia and abroad over the past ten years on the extraction of rare earth elements (REEs) with binary mixtures of extractants of various classes. It was noted that high values of REE separation coefficients are in the most cases achieved by increasing the selectivity of the extractant mixtures used due to the formation of complexes of mixed composition in the organic phase. In addition, in some systems with mixtures of extractants, the processes of stripping metals from the organic phase are facilitated.
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