Titanium Metal Production Research Articles

Carbochlorination of YOCl for Synthesis of YCl3

AbstractAs the production of high-quality titanium (Ti) metal increases significantly, the generation of low-quality Ti scraps increases and exceeds the demand for current cascade recycling in ferrous metallurgy. Therefore, the development of an upgrading recycling technology, in which scraps are refined and reutilized, is required. The magnesium (Mg) deoxidation assisted by the formation of oxychlorides of rare earth metals is currently considered a promising process for upgrading recycling technology, during which YOCl is formed as a byproduct. In this study, we investigate the synthesis and separation of YCl3 from YOCl via carbochlorination at 973 and 1073 K and confirmed that YCl3 can be regenerated from YOCl at a high conversion rate (82.7 pct at maximum). YCl3 was also formed even in the presence of MgCl2; however, MgCl2 decreased the conversion rate (49.8 pct at minimum). The conversion rate in the temperature region where YCl3 is a liquid (1073 K) was lower than that in the temperature region where YCl3 is a solid (973 K). Therefore, an operation with temperature cycling, in which YCl3 is formed at a temperature where YCl3 is a solid and then the temperature is increased to a temperature where YCl3 is a liquid to drain the molten mixed salt, is efficient.

Study on a new molten salt for electrolytic preparation of Ti: dissolution mechanism and kinetic analysis of TiO2 in NaCl-KCl-K2TiF6

Understanding the dissolution behavior and reaction rate of TiO2 in the NaCl-KCl-K2TiF6 electrolyte system is paramount for the advancement of a novel titanium metal production process. Initially, the liquidus temperature of the electrolyte system decreases with an increase in K2TiF6 content or the addition of a small amount of TiO2. Kinetic analysis reveals that the dissolution of TiO2 in the electrolyte follows a zero-order reaction for the first 30 min, with an activation energy of 2.46 × 105 (J/mol). The saturation concentration of TiO2 is reached at 300 min, and higher reaction temperatures or increased K2TiF6 content enhance the solubility of TiO2 in the electrolyte. In addition, the regression equation Y = − 25.02096 + 1.06412x1 + 0.0362x2 among the solubility of TiO2 (Y), the ratio of fluoride to chloride in electrolyte (x1) and experimental temperature (x2) was established by multivariate regression model. The analysis indicates that TiO2 dissolves in the electrolyte system as a complex K2NaTiOF5, releasing TiOF2 gas during the reaction. Finally, characterization studies on the elemental composition, chemical state, molecular structure, and material morphology of K2NaTiOF5 complex and TiOF2 gas reveal even distribution of elements. The K2NaTiOF5 complex molecules exhibit irregularly polygonal dispersion, while TiOF2 exists as agglomerated particles.

A novel low‐energy approach to leucoxene concentrate desiliconization by ammonium bifluoride solutions

AbstractBACKGROUNDDespite the large reserves of titanium ores, their treatment by basic approaches to obtain titanium products is not always economically feasible due to various factors. One of these problems is the high content of silicon in the ores.RESULTSThe paper considers the desiliconization of a leucoxene concentrate with an aqueous solution of ammonium bifluoride. It was found that at 80 °C the main impurities, such as silicon and iron, pass into solution in the form of corresponding ammonium–fluorine complex compounds.CONCLUSIONSThe degree of desiliconization was up to 99%. Aluminium reacts with ammonium bifluoride, but is almost not leached into solution due to its low solubility. Titanium does not react due to its relatively higher reaction Gibbs energy among other metals in reaction with ammonium bifluoride. The content of titanium oxide in the calcined leaching residue was 85.52 wt%. The resulting residue corresponds to the raw material used in industry for the production of titanium dioxide pigment or titanium metal by the chlorine method. Iron and silicon can be precipitated from the leaching solution. Furthermore, the resulting filtrate can be evaporated in order to regenerate and reuse ammonium bifluoride. © 2022 The Authors. Journal of Chemical Technology and Biotechnology published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry (SCI).

Thermodynamics and Kinetics Research of the Fluorination Process of the Concentrate Rutile

The growth in the production of titanium metal and its compounds leads to an increase in the amount of toxic waste. As a result, at the legislative level, emissions of such wastes are limited, which leads to a drop in the production of titanium-containing products and a shortage of titanium in the international market. This paper presents the results of the process of fluorination of rutile concentrate from the Tarsky deposit (Russia, Omsk region) with elemental fluorine using a laboratory setup of a special design. For fluorination, samples of rutile concentrate weighing 0.1–1.0 g were used. The particle size distribution of particles varied from 2 × 10−6 to 2 × 10−5 m. To determine the possibility of carrying out the process, the calculation of the change in the logarithm of the equilibrium constant versus temperature was performed. The influence of the following operating parameters on the fluorination process has been studied: various concentrations of F2 in a fluorinating mixture of fluorine with nitrogen; process time from 0 to 9 min; different ratios of the initial solid phase to fluorine (10 and 50% excess of fluorine and 10 and 50% of its deficiency); fluorination temperature in the range of 300–1800 K. A kinetic equation is selected that most accurately describes the fluorination process. The values of the activation energy and the preexponential factor in the kinetic equation are determined. The obtained results show that with an increase in the fluorine content in the fluorinating gas mixture and the temperature of the process, the fluorination rate increases. Optimal conditions for fluorination: temperature—680 K; time—5 min excess fluorine in the fluorinating mixture—20–25%. The obtained results allow to propose and consider the conditions of process execution on industrial equipment.

Assessment of Occupational Health Risks from Exposure to Titanium Alloys Based on the Results of Periodic Medical Examinations and Doctor’s Visits

Introduction: The titanium industry continues to build capacity and introduce innovative technologies driven by high demand for the metal and its alloys. High occupational risks of diseases of the respiratory and circulatory systems, diseases of the skin, and changes in hematological indices were established for titanium metal production workers. The objective of our study was to assess the occupational risk from exposures to titanium in the composition of industrial aerosols for the health of workers in the modernized areas of metallurgical production. Materials and methods: Our risk assessment was based on findings of periodic health examinations and doctor’s visits; we estimated the relative risk (RR) and used χ2 criterion to evaluate the statistical significance of the results. Results: We observed significantly higher incidence rates of diseases of the skin, ear, respiratory and musculoskeletal systems with temporary disability and higher rates of chronic diseases of the skin, respiratory and digestive systems in the titanium metal production workers compared to the workers of the same industrial enterprise unexposed to titanium and its alloys. Chronic diseases developed quicker in the exposed workers of all age groups than in the controls. The prevalence of hematologic disorders, such as high hemoglobin levels, thrombocytopenia, leukocytosis, lymphocytosis, and monocytosis was also higher in the exposed group. In the workers exposed to titanium concentrations exceeding the maximum permissible concentration (MPC) of 10 mg/m3 in the workplace air, we noted significantly higher rates of chronic diseases of the skin and digestive system, elevated hemoglobin levels, and a rising trend in the prevalence of chronic diseases of the circulatory system, high blood pressure, overweight, and thrombocytopenia in comparison with those working in permissible conditions. Conclusions: We revealed a strong correlation between occupational exposures to airborne titanium and chronic skin diseases and a medium correlation for leukocytosis and monocytosis.

Fundamental problems and prospects for the use of titanium raw materials in Russia

The article provides a detailed analysis of research results on the use of various types of titanium raw materials from Russian deposits: primary (titanomagnetite, ilmenite-titanomagnetite), metamorphosed (buried leucoxene and ilmenite-leucoxene sandstones) and complex zircon-rutile-ilmenite placers. All titanium deposits in Russia are characterized by low ore quality, which does not meet technological requirements for the production of pigment TiO 2 and metallic titanium. Main deposits are based on titanomagnetites containing from 3 to 17 % of TiO 2 . Ilmenite is in a subordinate position. Leucoxene sandstones of the Yarega deposit have high titanium content (about 10 %o TiO 2 ). But when they are dressed by known methods, low-quality high-silicon leucoxene concentrates are obtained containing 40 - 50 %o TiO 2 with significant titanium losses. Ilmenite-leucoxene sandstones of the Pizhemskoe deposit contain 3 - 10 %o of TiO 2 . The main titanium-containing phases are pseudorutyl Fe 2 O 3 3TiO 2 and leucoxene. The cementing binder of grains in sandstones is siderite with magnetic properties, which greatly reduces the degree of minerals disclosure during crushing and worsens the conditions for ore dressing in general. Ilmenite-bearing placers consist of fine-grained disseminated ilmenite and are difficult to concentrate. Complex zircon-rutil-ilmenite placers are infected with chromium and other undesirable impurities, which do not allow existing dressing methods to obtain a conditioned ilmenite concentrate. The main problems of using hard-to-concentrate titanium ores of all the above types of deposits and scientifically based ways to solve them are discussed. It is aimed at obtaining high-quality raw materials for the production of titanium metal and pigment TiO 2 with the simultaneous extraction of other valuable components. Particular attention is devoted to studies on the use of mass complex raw materials - titanomagne-tites, which are allocated in three phased directions, lasting for about 200 years - from the beginning of the XIX century to the present.

Processing Breakthrough Improves Titanium Yield

Abstract A chance discovery is enabling significant efficiency gains in titanium conditioning, one of the most costly steps in titanium metal production.

Моделирование тенденций рынка металлического титана

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.

Research and Development of Ti and Ti alloys: Past, present and future

This study provide an insight of established and future research and development on Titanium metal production, Titanium alloy development, Titanium powder metallurgy, and thermomechanical and manufacturing processes. In the last 60 years, research initiatives were investigating the cost effective alternative ways of producing Titanium metal from rutile, ilmenite and synthetic rutile. The very recent research focuses on the combination of pyro and hydrometallurgical process to produced synthetic rutile from ilmenite. Chloride leaching and solvent extraction will be significant strategies to reduce operating costs and protect the environment. New and developed processed for production of Titanium will be mostly focussed on direct electrowining of synthetic rutile or beach sand. Future perspectives associated with alloy development, biomedical, additive manufacturing, and Titanium powder metallurgy emerging techniques such as hydrogen sintering and phase transformation, and cold gas dynamic spraying or Titonic Kinetic Fusion are discussed.

Development status of the CSIR-Ti Process

South Africa is endowed with significant titanium-bearing reserves, which are concentrated to produce slag and exported as a low-value commodity, meeting about 20% of the global demand for the production of titanium dioxide pigment. Compared to the well-established titanium pigment industry, the much smaller titanium metals industry holds significant growth potential. Titanium metal is however notoriously difficult to refine from its abundant ores, and machining titanium is known to be challenging. Titanium usage is thus limited to niche applications in aerospace, defence, medical and chemical industries. Titanium powder produced at low cost promises a paradigm shift in titanium market size. Titanium powder has not been produced directly at commercial scale from titanium tetrachloride (TiCl4), which is the precursor for both pigment and metal production. The Titanium Centre of Competence (TiCOC) at the Council for Scientific and Industrial Research (CSIR) has as its aim the establishment of a titanium metals industry in South Africa. To this end research and development work is being conducted towards the commercialisation of the CSIR-Ti process, a potentially cost-effective method for titanium metal production. This article discusses the history of the CSIR-Ti process for titanium metal powder production, challenges addressed, current development status and the unique products achieved.

Mechanisms of Hydrogen-Assisted Magnesiothermic Reduction of TiO2

Direct reduction of TiO2 powder has been attempted for decades by researchers in an effort to decrease titanium (Ti) metal production costs. The main objective has been to avoid energy-intensive steps involved in production of primary Ti by the Kroll process. The emerging hydrogen-assisted magnesiothermic reduction process, which uses Mg to directly reduce TiO2 powder under a H2 atmosphere, has been shown to have the potential to compete directly with the Kroll process. The present studies represent an effort to understand the reduction reaction mechanisms of this process. Phase transformations and the reaction pathways are examined by SEM/EDX analysis of partially reduced powder cross-sectional, X-ray diffraction, and other analytical techniques. The results show important morphological changes, the prominent intermediate and final phases under the H2 atmosphere, as well as the local deposition behavior of the MgO byproduct. The effect of the specific surface areas of the initial particles is also discussed.

Comparison of Methods for Electrochemical Iron Removal from Titanium Ores

Titanium metal production by the Kroll process requires a high-grade ore material as a feedstock for chlorination, such as natural or synthetic rutile. Electrochemical methods for making titanium have generally required even higher purity. This paper describes different methods for iron removal from a pseudorutile mineral sand for the eventual goal of producing commercially pure titanium powder by the MER electrochemical process. One method involves the dissolution of the Fe $$_2$$ O $$_3$$ content of the ore in an alkali chloride molten salt, followed by plating to remove the dissolved species as metallic iron. The other method described involves the reduction of the ore to titanium oxycarbide, which also reduces iron and some other metal oxides present to metallic form. This reduced material is used as an anode in an electrochemical cell, and the metallic impurities are selectively removed by careful control of the anode potential. The products of both processes are compared with respect to their impurity contents, and their potential applications to different titanium production methods are also examined.

Reduction of Titanium Dioxide to Metallic Titanium by Nitridization and Thermal Decomposition

We report a novel process to produce metallic titanium from titanium dioxide—the raw material typically used in the conventional production of titanium metal—via a titanium nitride (TiN) intermediate. TiN is more easily reacted than titanium oxides such as titanium monoxide and titanium dioxide, and shows thermodynamic reactivity equivalent to titanium tetrachloride (TiCl4), which is used industrially as an intermediate in the conventional metallic titanium manufacturing process. The thermal decomposition temperature of TiN (～3500 K), determined from a thermodynamic database, is also significantly lower than those of the oxides (～5300 K) and TiCl4 (～6200 K); thus, it is suitable for use in the available temperature range of an electric arc furnace (～4000 K). Here, we demonstrate the use of TiN as an intermediate for the manufacture of metallic titanium by thermolysis using the arc melting method.

Selective Removal of Iron from Low-Grade Ti Ore by Reacting with Calcium Chloride

Recently, titanium metal production by molten salt electrolysis using CaCl2 as molten salt and TiO2 or rutile (94 to 96 pct TiO2) as feedstock has been drawing attention. However, when a low-grade Ti ore (mainly FeTiO3) is used as feedstock, removal of iron (Fe) from the ore is indispensable. In this study, the influence of reaction temperature, reaction time, particle size of the ore, and source country for the ore on the removal of iron by selective chlorination using CaCl2 was assessed. Experimental results showed that the mass percent of iron in the ore decreased from 49.7 to 1.79 pct under certain conditions by selective removal of iron as FeCl2. As a result, high-grade CaTiO3 was produced when the ore particles smaller than 74 µm reacted with CaCl2 at 1240 K (967 °C) for 8 to 10 hours. Therefore, this study demonstrates that the removal of iron from the ore is feasible through the selective chlorination process using CaCl2 by optimizing the variables.

Hydrogen assisted magnesiothermic reduction of TiO2

Abstract The development of low cost titanium metal production processes has challenged the Ti research and industrial communities around the world for decades. The strong affinity of titanium to oxygen dictates that it is very difficult to produce low-oxygen Ti metal from TiO2 directly. In this paper, a hydrogen assisted magnesiothermic reduction (HAMR) process for producing Ti metal powder from TiO2 powder at relatively low temperatures (⩽750 °C) is established. The overall approach is based on the thermodynamic tuning of the relative stability of MgO versus that of Ti-O solid solutions by temporarily alloying the system with hydrogen. It is shown that Ti-H-O solid solutions are less stable than their corresponding Ti-O solid solutions, which changes the reaction of Mg with Ti-O from being thermodynamically unfavorable to being favorable. The key steps for producing pure Ti metal powder from TiO2 involve Mg reduction of TiO2 in a hydrogen atmosphere which produces porous TiH2, a heat treatment procedure to consolidate the powder and reduce specific surface area of the powder, and the final step to deoxygenate the powder using Mg in a hydrogen atmosphere to further reduce the oxygen content. This paper systematically examines the changes of oxygen content, phase transformations, and the evolution of the morphology of the particles during the entire process. The results show that this approach has great potential to be a viable method for the production of low-oxygen Ti metal powder from TiO2. In addition, the effect of hydrogen on the oxidation of Ti powder is analyzed using XPS, which reaffirms that titanium hydride is more impervious to surface oxidation than Ti metal, another crucial advantage of using hydrogen atmosphere.

Direct reduction of synthetic rutile using the FFC process to produce low-cost novel titanium alloys

Typically, pure TiO2 in pellet form has been utilised as the feedstock for the production of titanium metal via the solid state extraction FFC process. For the first time, this paper reports the use of loose synthetic rutile powder as the feedstock, along with its full characterisation at each stage of the reduction. The kinetics and mechanism of the reduction of synthetic rutile to a low oxygen titanium alloy have been studied in detail using a combination of X-ray diffraction, scanning electron microscopy, oxygen analysis, and X-ray fluorescence techniques. Partial reductions of synthetic rutile enabled a reaction pathway to be determined, with full reduction to a low oxygen titanium alloy occurring at 16 h. Major remnant elements from the Becher process within the feedstock were followed throughout the process, with a particular emphasis placed on the reduction behaviour of iron within the alloy. Although impurities such as Fe, Al, and Mn are found in the feedstock and alloy, no major deviations from previously reported reaction mechanisms and phase transformations utilising a pure porous (25–30 % porosity) TiO2 precursor were found. Following reduction, the titanium alloy powder produced from synthetic rutile (approx. 3500 ppm oxygen) has been consolidated via an emerging rapid sintering technique, and its microstructure analysed. This work will act as the baseline for future alloy development projects aimed at producing low-cost titanium alloys directly from synthetic rutile. Producing titanium alloys directly from synthetic rutile may negate the use of master alloy additions to Ti in the future.

Development of a niobium-doped titania inert anode for titanium electrowinning in molten chloride salts.

The direct electrochemical reduction of solid titanium dioxide in a chloride melt is an attractive method for the production of titanium metal. It has been estimated that this type of electrolytic approach may reduce the costs of producing titanium sponge by more than half, with the additional benefit of a smaller environmental footprint. The process utilises a consumable carbon anode which releases a mixture of CO2 and CO gas during electrolysis, but suffers from low current efficiency due to the occurrence of parasitic side reactions involving carbon. The replacement of the carbon anode with a cheap, robust inert anode offers numerous benefits that include: elimination of carbon dioxide emissions, more efficient cell operation, opportunity for three-dimensional electrode configurations and reduced electrode costs. This paper reports a study of Nb-doped titania anode materials for inert anodes in a titanium electrolytic reduction cell. The study examines the effect of niobium content and sintering conditions on the performance of Nb-doped TiO2 anodes in laboratory-scale electrolysis tests. Experimental findings, including performance in a 100 h laboratory electrolysis test, are described.

A novel chemical pathway for energy efficient production of Ti metal from upgraded titanium slag

The developments of energy efficient, low cost titanium metal production processes have challenged the metallurgical industry and research community around the world for several decades. The strong affinity of titanium to oxygen dictates that the conventional Ti metal production processes are energy-intensive. In this paper, a new approach that is designed to minimize energy consumption and overall cost for Ti production is presented. The overall approach is based on a chemical pathway that synergistically integrating a series of low cost unit processes to produce Ti that can match the quality of the product produced by the Kroll process commercially to date. The key steps include production of purified TiO2 with controlled sizes and morphologies, Mg reduction in the presence of hydrogen to form porous TiH2, heat treatment to close the pores, and Ca de-oxygenation to reduce oxygen content to less than 0.15wt%. The results show that this approach can indeed produce Ti metal powder that has high purity, low oxygen, and meets the specifications by ASTM for general purpose Ti sponge, directly from upgraded titanium slag (UGS) without the high temperature chlorination step.

Kinetic studies on the reoxidation of beneficiated ilmenite by non-isothermal thermogravimetric analysis

Synthetic rutile is an important titanium feedstock for the production of titanium dioxide pigment and titanium metal. More attention is focussed in recent years on the development of environment friendly processes for the production of synthetic rutile with minimum acidic effluents. CSIR-NIIST, Trivandrum, India, had successfully developed a more environment friendly process for the production of high grade synthetic rutile containing more than 94% TiO2. The process is comprised of metallisation of ilmenite followed by aeration rusting for the production of beneficiated ilmenite and the reoxdiation of beneficiated ilmenite followed by acid leaching. Reoxidation of beneficiated ilmenite plays a major role in rendering the product amenable to acid attack and removal of residual iron. This paper describes in detail the kinetic studies carried out on the reoxidation of beneficiated ilmenite by thermogravimetric technique under non-isothermal conditions. Assuming the oxidation mechanism to be in the form (1 - α)n and considering a contracting spherical model with n = 2/3, the basic equation of non-isothermal reaction was analysed and solved by integral approach. The kinetic parameters such as activation energy, pre-exponential factor and the order of the oxidation reaction were computed from the weight gain data under linear rise in temperature. The paper also discusses the optimisation of reoxidation temperature and residence time for the maximum removal of iron during acid leaching, which in turn results in synthetic rutile of maximum TiO2 content.

Hydrolysis of TiOCl2 leached and purified from low-grade ilmenite mineral

Low grade ilmenite (FeTiO3) is not suitable for the production of titanium metal or TiO2 due to its high iron content. An economic process is devised for extraction and purification of titanium as TiOCl2 solution from low-grade ilmenite. The extracted TiOCl2 solution could be transformed to rutile, anatase or a mixture of them by hydrolysis under different conditions. The microstructure morphology of the obtained products was investigated using SEM and TEM. Hydrolysis under open atmosphere at 100°C for 6h gives a very stable suspension of anatase with nano-leaf morphology. On the other hand, hydrolysis under closed hydrothermal condition at 100°C and 120°C gives mainly rutile. A mixture of rutile and anatase was obtained by hydrothermal hydrolysis at 150°C, while at 180°C the main phase was anatase.