E. N. Selivanov

Thermal expansion and phase transformations of copper sulfides

The microstructure and phase transformations of copper sulfides have been studied by thermal analysis, microstructural analysis, and x-ray diffraction during heating in an inert atmosphere. The unit-cell parameters of Cu1.8S, CuS, Cu1.96S, and a Cu1.8+xS (0 < x ≤ 0.2) solid solution have been determined as functions of temperature.

Composition, Structure, and Thermal Expansion of Ca3Fe4S3O6 and CaFeSO

The iron calcium oxysulfides Ca3Fe4S3O6 and CaFeSO are synthesized by reacting mixtures of CaO and FeS in an inert atmosphere. Their elemental compositions and lattice parameters are determined by x-ray microanalysis and x-ray diffraction. From the temperature-dependent lattice parameters of the oxysulfides (measured up to 1020 K), their thermal expansion coefficients are evaluated.

Thermal expansion of CaZnSO

The temperature stability range of the zinc calcium oxysulfide CaZnSO has been determined in an inert atmosphere using high-temperature x-ray diffraction, thermogravimetry, and x-ray microanalysis. The lattice parameters and thermal expansion coefficients of CaZnSO have been measured in the range 298–1170 K and have been represented by best fit equations.

Thermal expansion and phase transformations of natural pyrrhotite

The phase transformations of natural hexagonal pyrrhotite have been studied by high-temperature x-ray diffraction and thermogravimetry during heating in an inert atmosphere, and its unit-cell parameters have been measured during heating to 1060 K.

Thermodynamics and kinetics of thermal dissociation of dolomite

The results of investigations into thermodynamic foundations and kinetics of thermal dissociation of dolomites of Ural deposits are presented. Dolomite samples are characteristic of the fraction and coarseness of calcite inclusions, which determines distinctions in their dissociation kinetics. It is established that dolomites dissociate according to the two-stage model limited by the reaction on a three-dimensional surface at the first stage and kinetic equation having the order close to 0.3 and 0.3 at the second stage.

Thermal and thermomagnetic properties of pyrrhotites

A comparative analysis of the thermal and magnetic properties of synthesized samples of troilite (FeS) and hexagonal (Fe0.94S) and monoclinic (Fe0.875S) pyrrhotites was performed by X-ray diffraction, combined thermogravimetric analysis and calorimetry, and thermomagnetic measurements. The pyrrhotite composition affects the temperatures and heats of phase transitions of the samples during heating and cooling in the range of 300–670 K. The temperature and the magnetic field strength determine the magnetization of pyrrhotites. Higher magnetization is inherent in monoclinic pyrrhotite, while troilite has lower magnetization.

Thermal magnetic hysteresis of nickel-doped pyrrhotites

The magnetic properties of polycrystalline natural pyrrhotite samples with low-nickel contents and synthesized Fe0.675Ni0.2S and Fe0.475Ni0.4S pyrrhotites are investigated. All of the investigated pyrrhotites are shown to have a thermal magnetic hysteresis in the region of 298–623 K. As a result, there is not only an increase in the difference between the magnetic moment values of the materials after a heating-cooling regime, but also a change in their magnetic state.

Structure and properties of the slags of continuous converting of copper nickel-containing mattes and concentrates: II. Effect of the SiO2/CaO ratio on the structure and liquidus temperature of the slags

The structure and liquidus temperature of the SiO2-CaO-Al2O3-FeOx-Cu2O-NiO slags that form during continuous converting of copper mattes and concentrates into blister copper are analyzed. The slag melt compositions are varied over a wide SiO2/CaO range. The slags are studied by X-ray diffraction, scanning electron microscopy, and electron-probe microanalysis. The liquidus temperature of the slags is determined by differential thermal analysis. It is found that, depending on the SiO2/CaO ratio, the structure and liquidus temperature of the slags change and the forms of copper in a slag also change. The SiO2/CaO range in a slag is recommended for the process of continuous converting of a copper nickel-containing sulfide raw materials.

Phase composition and the chemistry of oxidation of nickel converter matte

High-temperature X-ray diffraction analysis, thermogravimetry, mass spectrometry, and mineralographic and X-ray microprobe analyses are used to study the structure and the phase and elemental compositions of a commercial nickel converter-matte sample. The sequence of the transformations and processes that occur during heating of the nickel converter matte in air to a temperature of 1300 K are determined.

Formation of metallic phase on reducing-gas injection in multicomponent oxide melt. Part 2. Density and surface properties

The density and surface tension of melts of ferronickel (0–100% Ni) and oxidized nickel ore are measured by the sessile-drop method, as well as the interface tension at their boundary in the temperature range 1550–1750°C. The composition of the nickel ore is as follows: 14.8 wt % Fetot, 7.1 wt % FeO, 13.2 wt % Fe2O3, 1.4 wt % CaO, 16.2 wt % MgO, 54.5 wt % SiO2, 4.8 wt % Al2O3, 1.5 wt % NiO, and 1.2 wt % Cr2O3. In the given temperature range, the density of the alloys varies from 7700 to 6900 kg/m3; the surface tension from 1770 to 1570 mJ/m2; the interface tension from 1650 to 1450 mJ/m2, the density of the oxide melt from 2250 to 1750 kg/m3; and its surface tension from 310 to 290 mJ/m2. The results are in good agreement with literature data. Functional relationships of the density, surface tension, and interphase tension with the melt temperature and composition are derived. The dependence of the alloy density on the temperature and nickel content corresponds to a first-order equation. The temperature dependence of the surface tension and interphase tension is similar, whereas the dependence on the nickel content corresponds to a second-order equation. The density and surface tension of the oxide melt depend linearly on the temperature. The results may be used to describe the formation of metallic phase when carbon monoxide is bubbled into oxide melt.