Abstract: Titanium is the “wonder” metal, which makes sense as the material of choice for a wide variety of applications. However, because of its relatively high price- a result of extraction and processing costs- it is used basically only when it is the only choice; with the caveat that titanium has a bright “image” which can lead to use even when the economics are unfavorable. The major thrust in the area of titanium technology has been aimed at achieving cost reduction rather than developing alloys with enhanced properties. This paper will overview the potential areas which are amenable to cost reduction and present some applications of titanium and it’s alloys.
Abstract: The FFC-Cambridge process is a molten salt electrochemical deoxidation method that was invented at the Department of Materials Science and Metallurgy of the University of Cambridge one decade ago. It is a generic technology that allows the direct conversion of metal oxides into the corresponding metals through cathodic polarisation of the oxide in a molten salt electrolyte based on calcium chloride. The process is rather universal in its applicability, and numerous studies on metals, semimetals, alloys and intermetallics have since been performed at the place of its invention and worldwide. The electro-winning of titanium metal is a particularly rewarding target because of the disadvantages of the existing extraction methods. This article summarises the research work performed on the FFC-Cambridge process at the University of Cambridge and its industrial partners with a focus on the electro-winning of titanium metal from titanium dioxide. Topics addressed encompass the invention of the process, early proof-of-concept work, the identification of the reaction pathway, and the investigation and optimisation of the key process parameters. Also discussed are aspects of technology transfer and some of the development work undertaken to date.
Abstract: Electrochemical methods and electrowinning of titanium have been promoted, unsuccessfully, for many years as a replacement for the current Kroll process, which has not achieved the same economies of scale as other light metals (eg. Al, Mg) have. One such method is the direct electrochemical reduction of titanium dioxide, which encompasses a range of processes involving the electrolysis of a molten salt and the subsequent reduction of titanium via the metal of the salt cation. Norsk Titanium AS, in a collaboration with Norsk Hydro, SINTEF, and NTNU through a Norwegian Research Council grant, has been actively involved in the development of such a process and the focus of this presentation is to give a summary of the research activities. Particular emphasis will be given to the fundamental reactions underlying the process.
Abstract: It has long been a goal to produce Ti Alloy powder directly to eliminate the standard processing of melting sponge, alloying, producing a billet/ingot and then reducing to powder by one of several techniques. The batch Kroll process where reaction occurs at the reactor wall interface from TiCl4 vapor and molten magnesium, limits the potential to directly form alloys. Any batch processing has the limitation of alloy compositional control from batch to batch. A unique continuous processing approach permits the gaseous mixing of chloride precursors with metallothermic reduction that directly produces an alloy powder in a size that is useable for standard powder metallurgy. Discussion will include producing Ti-6Al-4V and other alloy powder.
Abstract: The present work deals with the investigation of an electrolytic method for titanium production that uses TiO2 enriched titania slag as raw material. The process involves two steps: i) carbothermal reduction of the slag to form titanium oxycarbide powder; and ii) electrolysis in a molten chloride-based electrolyte using a titanium oxycarbide consumable anode.
Electrochemical studies show the stability of the different Ti species in the equimolar NaCl-KCl melt at 850oC. These results, together with previous work about the anodic oxidation mechanism of a consumable titanium oxycarbide anode in molten chlorides, allow us to optimize the anode and cathode voltages in the electrolysis experiments.
The results show that best quality titanium deposits are obtained when the reduction occurs in a single electrochemical step, i.e. directly from di-valent titanium species to Ti metal. Then, the complete conversion of the Ti(III) ions released from the consumable oxycarbide anode to Ti(II) species by adding Ti sponge to the electrolyte, must be fulfilled.
Abstract: In the standard Kroll process reaction between the TiCl4 and Mg is at the reactor wall interface that limits the potential to design a continuous process. Many alternatives have been investigated over the past 70 years to engineer a continuous process utilizing metallothermic reduction of TiCl4. Approaches utilizing burner type architectures for continuous processing result in unacceptable very fine Ti powder. A unique process that operates continuously and produces controlled size powder that can be directly utilized in standard powder metallurgy, rapid manufacturing, or substituted for sponge will be discussed.
Abstract: DARPA instituted an Initiative in Titanium in 2003 to produce titanium, alternatively to the Kroll process, in a billet form for under $4/lb. This DARPA sponsored program has gone into Phase II consisting of utilizing ore/TiO2 as a feed. The TiO2 is carbothermically reduced to a suboxide-carbide (Ti:O:C) which is used anodically to resupply the titanium content in an electrolysis process that deposits titanium in a powder morphology. The deposited powder is uniquely stripped from the cathodes and harvested in a separate stream that permits continuous electrolytic processing to produce titanium at an estimated cost about ½ the Kroll process. Oxygen contents less than 500 ppm are achievable with particle sizes in the desired range for powder metallurgy applications. The process has been demonstrated on a continuous basis and is in the stage of scaling-up to 500 lbs/day.
Abstract: The current status and recent advancements in the use of the FFC Cambridge process for the production of low cost titanium and titanium powders is presented. This will include an overview of the process, current and future process equipment and recent results in terms of chemistry, structure and properties of powder and consolidated product. The future direction and activities for the FFC Cambridge process will also be briefly discussed.
Abstract: Direct electrolysis of Ti and its alloys has been attempted by the process using a DC-ESR unit. The concept of the process is explained in detail, and the expected key issues are commented. Liquid Ti metal was obtained in a CaF2-CaO-TiO2 bath, and electrolysis by using a new type of the electrolytic cell was also tried. Ti-Al alloy was successfully deposited in a CaF2-CaO-TiO2-Al2O3 bath, whereas Ti-Si alloy was not obtained in a CaF2-CaO-TiO2-SiO2 bath yet. Ti-Fe alloy was extracted in CaF2-CaO-TiO2-FeO bath of a particular composition. A common correlation between the cathodic current efficiency and the average consumed electric power seen in the Ti, Ti-Al and Ti-Fe electrolysis suggested the importance of sufficient temperature in the process. The bath composition also affected the temperature through the change in the electric conductivity of the bath.