Gipronickel Institute

Nickel-rich layered oxides are currently the preferred cathode active materials (CAMs) for lithium-ion batteries. However, the performance of CAMs is known to degrade when they are stored in ambient air due to surface reactions of the material containing residual lithium ions with atmospheric moisture and carbon dioxide to form lithium hydroxide and lithium carbonate. The residual lithium compounds on the CAM surface increase manifold upon long-term storage in contact with the atmosphere (ambient storage), with an attendant degradation of the electrochemical performance properties of the CAM, in particular, a 25% decline in specific discharge capacity at 0.1 C current density and a 50% decline at 1 C current density. New methods are proposed for the regenerating calcination of CAMs that have been stored in contact with air, and the addition of supplementary amounts of LiOH helps to achieve the highest capacitive characteristics of stored and then regenerated CAMs.

The present work aims to increase the alumina percentage recovery (APR) extracted from kaolinviathe addition of 0.5–4.0 wt.% charcoal as a thermochemical fluxing agent in the lime-sintering process at 1260–1360°C. The transformation, microstructural and microtextural changes and self-disintegration performance were characterized using thermogravimetric analysis and differential scanning calorimetry, X-ray diffraction/X-ray fluorescence, scanning electron microscopy coupled with energy-dispersive spectroscopy and laser diffraction particle-size distribution analysis. The optimum enhancement of APR, from 77.7% to 87.40%, was obtained by sintering at 1360°C with the addition of 1.5% charcoal. With further increase of the charcoal content to 4%, the APR reduced to 75.6%. Combustion of ≤1.5% charcoal provided additional heat that amorphized the crystalline calcium aluminate into highly leachable amorphous phases with improved self-disintegration efficiency. Sintering at temperatures of >1360°C or with charcoal contents >4% led to mullite crystallization and decreased alumina leachability, thereby reducing the APR. Charcoal is a cost-effective and energy-efficient activator to increase the APR extracted from kaolin.

The possibility of effective processing of oxidized nickel ores (ONOs) to form ferronickel in a barbotage unit (Vanyukov furnace for liquid bath melting (LBM)) is theoretically corroborated. The heat balances of the LBM processing of unreduced ONOs or the cinder preliminarily reduced in tubular kilns to form ferronickel are calculated. It is shown that deep reduction of ONOs and melting of the reduced cinder are energetically more favorable than direct melting of a slightly dried ore to form ferronickel. The proposed twostage scheme of processing of ONOs makes it possible to decrease the furnace area and the effluent gas flow. Parallel reduction and oxidation processes in the same region of a bubbled slag melt during direct melting of unreduced ore is debatable.

The viscosities of the slags that form during the continuous converting of copper mattes and concentrates into blister copper are determined. The compositions of SiO2-CaO-Al2O3-FeOx-Cu2O-NiO slag melts are varied over a wide range of (Fe + Ni) concentrations (25.5–40.2 wt %) and ratios SiO2/CaO (0.25–3.9) and (Fe)/(Cu + Ni) (0.4–1.6). The slag viscosity is measured by a vibrational method in the temperature range 1050–1450°C. The viscosity of a homogeneous melt is shown to be 0.5–2.0 P, and it increases sharply below the primary solidification temperature.

Data on the thermodynamic properties of boundary binary systems were used to calculate the activities of components in liquid alloys of the iron-cobalt-nickel ternary system at a temperature of 1600°C.

The dissociation energy of heteronuclear diatomic molecules with polar covalent bonds was calculated by the modified Pauling procedure taking into account the presence of an unpaired electron on one of the atoms.

Published data on phase transformations of iron, nickel and cobalt arsenides and sulfoarsenides under thermal treatment are reviewed.

With increasing amount of compact granules in autoclave nickel powder reduced with hydrogen from a basic nickel carbonate pulp, the apparent density and nickel content of the powder grow. A good-quality nickel powder for flame-spraying is composed of compact granules of spherical shape.