Quantifying Heat Transfer Characteristics of the Kroll Reactor in Titanium Sponge Production

Various reactors with different sizes have been widely used for the production of titanium sponge in the Kroll process. But the further commercialization of the forced heat transfer design of the Kroll reactor is limited by lack of standard parameter to evaluate its convective heat transfer characteristics. This work proposes to evaluate and compare the Kroll reactor with the dimensionless Nusselt number. The results shown that the heat transfer coefficients for both surfaces increase with the volume flow rate of cooling air for each dimensionless temperature, and the heat transfer coefficients of the external surface of the reactor are higher than that of the internal surface of the heater. And new correlations regarding the Nusselt number between the cooling air and the external surface of the reactor or the internal surface of the heater are obtained based on experimental data, while the characteristics of the cooling air, equipment and operation parameters are considered.

New insights into pathways and kinetic of magnesiothermic reduction of titanium tetrachloride in titanium metallurgy

There is still no consensus on the reaction pathways and kinetic modeling of magnesiothermic reduction of titanium tetrachloride, and the theoretical innovations are required for further research of titanium metallurgy. We determined efficient reaction pathways via chemical reaction stoichiometry methodology, and proposed an innovative kinetic modeling approach of magnesiothermic reduction of titanium tetrachloride. We explained the reaction pathways by the steps of the phase change near the gas-liquid interfaces, the homogeneous reaction in the gas phase, the heterogeneous reduction near the gas-liquid interfaces, and the like dissolves like in the liquid phase. Net chemical reaction rate of titanium sponge decreased with decreasing of titanium tetrachloride feeding rata and with increasing of gauge pressure. The excellent fitness of the reaction rate constants, f(Δp) and k(Tin), show that the proposed kinetic equation accuately describes the reaction mechanism, and is reasonable and acceptable for magnesiothermic reduction of titanium tetrachloride in titanium metallurgy.

Modelling of thermal regimes in the air cooling channel of the titanium reduction apparatus

Numerical modeling of thermophysical processes in the air cooling channel of titanium sponge reduction apparatus is performed. The cooling channel is an area bounded by a retort filled with liquid magnesium and the apparatus wall, on which heating elements are mounted. Air flows inside the channel, cooling the retort. A mathematical model is constructed based on unsteady Navier-Stokes equations in axisymmetric formulation using a k-ω SST turbulence model. The model takes into account the radiation heat transfer between the retort and reactor walls. Four variants of thermal boundary conditions are considered. The aim of this work is to create a mathematical model of conjugate heat transfer in an air channel. Based on this model, the temperature conditions of the retort wall are calculated and the profiles of the heat transfer coefficient along the retort wall for a wide interval of air flow rates are obtained. It is shown that temperature distributions along the retort are heterogeneous and strongly depend both on external boundary conditions and on the cooling intensity. Heat transfer coefficient distributions from its outer wall for different retort heating conditions are plotted and an empirical formula for calculating the profile of this coefficient is proposed.

Experimental Validation of an Inductive System for Magnesium Level Detection in a Titanium Reduction Reactor

In order to precisely determine the magnesium level in a titanium reduction retort by inductive methods, many interfering influences have to be considered. By using a look-up-table method, the magnesium level can be reliably identified by taking into account the interfering effects of the titanium sponge rings forming at the walls with their unknown geometrical and electrical parameters. This new method uses a combination of numerical simulations and measurements, whereby the simulation model is calibrated so that it represents the experimental setup as closely as possible. Previously, purely theoretical studies on this method were presented. Here, the practical feasibility of that method is demonstrated by performing measurements on a model experiment. The method is not limited to the production of titanium but can also be applied to other applications in metal production and processing.

Сrystalline microcone coatings on titanium sponge.

For the first time it was shown how to obtain microcone-shaped TiO2structures by means of anodizing of porous powder materials made of titanium sponge. It was established that during anodizing in 10 %Н2SO4+ 0,15 % HF electrolyte along with the growth of the X-ray amorphous nanoporous TiO2film a set of microcones with anatase crystalline structure is formed on the surface of titanium sponge powder particles. Microcones (height is up to 7m, base diameter is up to 5m) consist of multilayer nanoscale structures. Such structures are promising for the manufacture of new nanomaterials for catalytic and sensor devices.

Modeling of Titanium Metal Market Trends

The recent trends in the world output of titanium-containing concentrates and titanium sponge – intermediate product in the production of metallic titanium – has been studied. The differences in the dynamics of these indicators have been found due to the fact that titanium-containing concentrates are used not only as raw materials for the production of titanium metal. The clusters of the world's major producers of titanium-containing concentrates and titanium sponge have been identified. The range of factors potentially influencing the titanium sponge price dynamics has been studied; the independence of this dynamics from fluctuations in supply and demand and the price of raw materials has been shown. The results of activity of JSC “Corporation VSMPO-AVISMA” were analyzed. The study shows that the main factor determining the sales profit margin of the Corporation is the dynamics of the exchange rate; a quantitative assessment of the degree of such influence has been made.