A. T. Belyaevskii

The Corrosion Protection of Nickel Equipment in Chloride-Fluotantalate Melts

The possibility of corrosion protection of nickel equipment at 680–780°C in chloride-fluotantalate melts, used in the sodium-thermal production of tantalum capacitor powder, is investigated. It is shown that preliminarily adding tantalum powder (no less than 0.3 wt. % relative to K2TaF7) to the NaCl–K2TaF7 (ca. 14 mol %) melt prevents the nickel corrosion from starting just as the melt is fused; the electroless tantalum deposition on nickel starts, which results in the formation of a Ni3Ta–Ni2Ta intermetallic protective coating on the nickel surface. The effects of the exposure time and the melt temperature, as well as the tantalum powder content and dispersity, on the tantalum deposition are studied.

Pentlandite leaching in the FeCl3-CuCl2-HCl system

Pentlandite leaching in binary and ternary systems comprised of FeCl3, CuCl2, and HCl was studied. The degree of decomposition and recovery of pentlandite, as well as the kinetic characteristics of the process were examined in relation to the composition of solution.

Physicochemical simulation of calcite (dolomite)-FeSO4-H2O open systems

Effect of the chemical composition of carbonate minerals on the precipitation of iron from a Fe(II) sulfate solution was studied.

Interaction of khibins titanomagnetite concentrate with hydrochloric acid

The interaction of Khibins titanomagnetite concentrate (TMC) with hydrochloric acid solutions has been investigated. The decomposition of TMC in the HCl solutions has been optimized using factorial experimental design. The main factors in the efficiency of TMC decomposition with hydrochloric acid and in metal extraction into the filtrate are the HCl concentration, HCl input, processing temperature, and reaction mixture stirring time. By varying the decomposition conditions, it is possible to control the selectivity of the process: in TMC decomposition at a high temperature and a high acid concentration and input (t = 95°C, CHCl = 320−340 g/L, TMC (S): HCl (L) = 1: 10, τ = 4 h), the metals pass collectively into the solution with a large recovery factor (93–95%); at smaller values of the above parameters (t = 50−80°C, CHCl = 200–220 g/L, S: L = 1: 6–7, τ = 2 h), TMC decomposition proceeds more selectively towards iron and vanadium leaching into the solution with the minimum possible leaching of titanium (<15%).

A study of the mechanism and kinetics of interaction between nepheline powder and ammonium hydrofluoride

Behavior of a skeleton silicate, nepheline, in the reaction of fluorination with ammonium hydrofluoride was studied by means of differential-thermal, X-ray phase, and chemical analyses, IR spectroscopy, and scanning electron microscopy.

Electrochemical Oxidation of Galenite in Carbonate Solutions

Linear voltammetry, X-ray phase and differential thermal analyses, diffuse reflection IR Fourier spectroscopy, Raman spectroscopy, and scanning electron microscopy (SEM) were used to study the electrochemical oxidation of galenite in carbonate electrolytes.

Optimization of the composition and sintering conditions of high-voltage ZnO varistor ceramics

This paper presents a study aimed at optimizing the composition and sintering conditions of highvoltage ZnO varistor ceramics. We demonstrate that, with allowance for the cost of starting materials, the optimal composition of high-voltage ZnO varistor ceramics is as follows (wt %): ZnO, 90; Bi2O3, 2.76; Sb2O3, 1.92; Al2O3, 3.32; and Co2O3, 2. The optimal sintering conditions are isothermal holding at a temperature of 975°C for 2 h. The ceramics thus prepared have Vb = 4.5 kV/mm, α = 50, Il = 1.1 μA/cm2, density ρ = 5.67 g/cm3 (relative density of 96.1%).

Synthesis and study of photocatalytic oxide nanocomposites of titanium(IV) and cobalt(II)

The phase formation, texture, and photocatalytic activity of synthesized oxide nanocomposites of titanium(IV) and cobalt(II) have been studied in relation to the cobalt content and temperature of heat treatment. The high photocatalytic activity of optimum compositions has been recorded within the spectral range of visible light with λ ≥ 670 nm.

Synthesis and physicochemical properties of titanium(IV)- and cobalt(II)-Based photocatalytic oxide composites

We have studied the phase transitions, morphology, and photocatalytic activity of composites based on titanium(IV) and cobalt(II) oxides at Co doping levels from 0.5 to 60 wt % and heat-treatment temperatures from 80 to 1150°C. The highest photocatalytic activity under illumination in the spectral range λ ≥ 670 nm is offered by mesoporous X-ray amorphous and multiphase (X-ray amorphous phase, anatase, rutile, and CoTiO3) nanomaterials containing 5–20 wt % Co, whereas two-phase materials (rutile + CoTiO3) have the lowest photocatalytic activity.

Peculiar features of preparation and application of fractionated magnesia-silicate reagent

The properties of magnesia-silicate reagent prepared by thermal activation of serpentinite of varied dispersion were studied. The factors affecting the extraction of copper and nickel with polydispersed metaserpentine were determined