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Results of the studies of gold and silver extraction from persistent arsenopyrite geavioconcentrate are presented, starting with mechanochemical breakdown of the concentrate, subsequent cyanide leaching, electrolytic extraction of the metals from cyanide solutions, and ending with obtaining the finished products in the form of metal alloy. The cycling use of cyaniic solutions after electrolysis in leaching process is evaluated. Electrolytic extraction of gold and silver was carried out on the cathodes made of carbon fibre materials, followed by thermal treatment. The final products with gold and silver content up to 95 mass % were obtained. The results of subsequent industrial tests at a gold production plant showed that the use of mechanochemical breakdown and an experimental-industrial activator to obtain gold and silver from persistent arsenopyrite gravioconcentrates of the deposits situated in the north-eastern part of Kazakhstan allows an increase in the ate and degree of gold and silver extraction.

The effect of high-energy mechanical treatment on the formation of the structural-phase state of highly filled composite powders UHMWPE/BN, UPTFE/BN, UHMWPE/Fe/BN, UPTFE/Fe/BN is investigated. Mechanochemical synthesis of composites was carried out in a water-cooled planetary ball mill in the atmosphere of argon. The phase composition and structural characteristics were studied with the D8 Advance diffractometer (BRUKER). It was established that Fe/BN composites are formed as a result of mechanical treatment for 2 min in the mixture of iron with hexagonal boron nitride; in addition, the phases of cubic boron nitride, c BN, iron nitride, FeN_0.056, and iron boride, Fe₂B, appear. During the mechanochemical synthesis of the composites of Fe/BN with polymers UHMWPE and UPTFE, the size of the crystallites of cubic boron nitride increases slightly. Activation of the mixtures of polymers with hexagonal BN is not accompanied by the transition of hexagonal boron nitride to the cubic modification. Grinding of hexagonal BN crystallites is slower than in the mixtures with Fe/BN composite. IR spectroscopic studies showed that the size of the original particles of hexagonal BN affects the change in the supramolecular structure of the polymer, while the polymer molecules are not destroyed.

Mechanochemical formation of composites Fe/TiB2, W/TiB2, Fe/B4C and W/B4C was investigated. These composites may be used as fillers for ultrahigh-molecular polyethylene intended for protection from neutron and g-radiation. Mechanochemical synthesis of the composites was carried out in a planetary ball mill with water cooling in the atmosphere of argon. The phase composition, structural and morphological characteristics of the composites, and their thermal stability were studied by means of a set of physicochemical methods (X-ray phase analysis, scanning electron microscopy, thermal analysis). It is demonstrated that the composites Fe/TiB2, W/TiB2, Fe/B4C and W/B4C are formed during mechanical activation. They are composed of particles 0.5-1.0 μm in size, their shapes being close to spherical. The particles are agglomerated into larger formations 30-50 μm in size. The resulting composites exhibit thermal stability under heating to ~800 °C.

The structures of glycosides formed in the interaction of polyphenolic compound quercetin as a model aglycon with a carbohydrate anomer, by the examples of D-glucopyranose and L-rhamnopyranose, were considered by means of computer modelling. The probability for the simulated structures to exist was estimated relying on bonding energy (as a change in the system energy) for different versions of aglycon binding to carbohydrate. A preferable type of the formed structures is bidning between 3,5,7-hydroxyl group of quercetin with 1,4,6hydroxyl groups of D-glucopyranose or 1,2,4-hydroxyl groups of L-rhamnopyranose.

Temperature dependence of the formation of two-dimensional crystalline AlN phase on the (0001)Al2O3 surface under ammonia flow was investigated. Two regions were experimentally detected in the temperature dependence of the process rate. Within the region of relatively low temperatures (T < 940 °C), the rate of AlN formation is limited by chemical reactions. A kinetic scheme of the process was proposed, and effective kinetic constants of the main stages of the process were determined. At a higher temperature (T > 940 °C), the formation of the ordered AlN phase is determined by a continuous two-dimensional phase transition in the lattice gas formed on the surface of AlN cells. A three-parameter scheme is proposed to describe the process. A good agreement between theoretical and experimental isotherms was obtained for the following parameters of the lateral interaction between the filled AlN cells in the lattice gas: Ei = 0.725 eV - lateral repulsion of the neighbouring filled AlN cells; U = -0.725 eV - the energy of stabilisation arising during the formation of a filled cell; V = 0.09 eV - energy consumed for the formation of an intermediate metastable cell of the lattice gas. The critical temperature of phase transition is unambiguously determined by the established parameters of lateral interaction and is equal to 795 °C. The observed phase transition in AlN lattice gas is continuous because experiments were carried out at temperatures above the critical point.

Materials based on cerium dioxide are used in various fields of high-tech industry: from precision polishing of optical glasses and the production of high-strength ceramics to using them as three-route catalysts in engines and medical applications as biomimetics. Due to a wide range of practical applications of such materials, there is an actual task to develop a method for producing cerium oxide with the ability to control its textural characteristics. To solve this problem in this work, the method of thermal decomposition of the precursor Ce₂(C₂O₄)₃·10H₂O was chosen. The main advantage of this method is the possibility of obtaining products in the form of a pseudomorph consisting of nanoparticles of the product and preserving the shape and size of the crystals. In the course of the work, the conditions for obtaining pseudomorph were found, i.e. porous granules of cerium oxide nanoparticles, the size of which is set at the stage of synthesis of precursor crystals. Techniques have been developed for growing Ce₂(C₂O₄)₃·10H₂O crystals of various sizes and habit. The work also revealed the factors that influence the textural characteristics of the resulting oxides during thermal decomposition of the selected precursor. It was shown that during thermal decomposition of thin (<20 µm) precursor plates with a basal face (010) in air, cerium dioxide pseudomorph transparent to visible light was formed. Thicker crystals were destroyed parallel to the (010) face with a fracture scale of about 10 μm. It was shown that an increase in water vapor pressure during dehydration led to structural changes other than those during dehydration in air. With such a rearrangement of the structure, the initial crystals are destroyed into particles less than 5 μm. In this work, we were able to obtain a pseudomorph consisting of 5-6 nm particles of cerium dioxide with a surface area of 140-150 m²/g and 40% porosity. Controlled annealing allowed the microstructure to be enlarged to the required size of crystallites that make up the pseudomorph.

The interaction of bismuth oxide with lactic acid solutions was studied by means of X-ray phase, chemical and thermogravimetric analyzes, IR spectroscopy and electron microscopy. The conditions for the formation of bismuth lactate of the composition BiC₉H₁₅O₉ were determined, and its solubility in an ammonium hydroxide solution was investigated. Studies show that it is expedient to carry out the synthesis of bismuth lactate BiC₉H₁₅O₉ through the interaction of bismuth oxide with lactic acid solution at a molar ratio of lactate ions to bismuth equal to 3.0, at the process temperature of 55±3 °C, followed by washing the product by isopropanol. When processing bismuth lactate BiC₉H₁₅O₉ with an aqueous solution of ammonium hydroxide, solutions with bismuth concentration of 245-380 g/l were obtained. They can be used to produce liquid bismuth lactate containing drugs. It was established that fine crystalline bismuth oxide can be obtained as a result of the thermal decomposition of bismuth lactate.

The effect of stoichiometric compositions and the conditions of mechanical activation on the formation of the product of WO₃ reduction by magnesium was studied by means of X-ray phase analysis. In the process of mechanical activation of a mixture of tungsten (VI) oxide with magnesium at the corresponding stages, mechanochemical composites of various compositions are formed, including magnesium, tungsten (VI and IV) oxides, magnesium tungstate, tungsten and magnesium oxide. The reduction of tungsten (VI) oxide with magnesium is completed by 8 minutes of activation with the formation of a W / MgO composite. The conditions for the acid separation of tungsten from magnesium oxide from mechanochemical composites W / MgO were determined. It was shown with the help of scanning electron microscopy that tungsten separated from magnesium oxide is highly dispersed and consists of primary particles that are close to spherical in shape, with sizes from 50 to 100 nm, aggregated into secondary particles 1 to 10 microns in size. Magnesium content in finely dispersed tungsten powder, determined by means of energy dispersive analysis, is less than 2%.

An overview of possible anionic substitutions in the structure of hydroxyapatite for the mechanochemical method of synthesis is presented. It was revealed that single-phase nanocrystalline varieties of anion-substituted hydroxyapatite are formed during mechanochemical synthesis. A series of the samples of carbonate-, silicate-, aluminate-, zirconate- substituted hydroxyapatites with different concentrations of the substituent ion were obtained. It was established that additional high-temperature annealing leads to partial loss of the substituent ion, which results in the formation of impurity phases. Silicate-, aluminate-, and zirconate-containing hydroxyapatite species may be of interest as coatings of medical implants made of metal and zirconium-corundum ceramics.

The article summarizes the results obtained in the studies of the distribution of thiocyanate acid complexes of iron (III), copper (II), cobalt (II), zinc and cadmium in extraction systems based on technical surfactants - potassium bis(alkylpolyoxyethylene) phosphate (oxyphos B) in the presence of sulphuric acid, alkylbenzyldimethylammonium chloride (catamin AB) in the presence of nitric acid at room temperature or their mixture at 50 ºC. It was established that the efficiency of individual surfactants as extractants is conserved both with inorganic salts and acids used as salting-out agents. It is shown that for oxyphos B extractability decreases as a sequence Fe(III) > Co(II) > Zn > Cu(II) > Cd, while for catamine AB the sequence is Cd ≈ Zn > Co(II) > Cu(II) > Fe(III), and in the case when a mixture of surfactants is used, oxyphos B is determining, which is confirmed by the extractability sequence: Fe(III) > Co(II) > Zn > Cu(II) > Cd. Oxyphos B is an analog of neutral oxygen-containing extractants, it concentrates thiocyanate acid complexes according to the hydrate-solvate mechanism, while catamin AB, anion-exchanging extractant. is more efficient in the extraction of thiocyanate complexes. The use of a mixture of the indicated surfactants allows one to carry out the process in more diluted solutions and to obtain synergetic effects in extraction.