Materials Week '97: Tuesday PM Session

Focusing on physical metallurgy and materials, Materials Week '97, which incorporates the TMS Fall Meeting, features a wide array of technical symposia sponsored by The Minerals, Metals & Materials Society (TMS) and ASM International. The meeting will be held September 14-18 in Indianapolis, Indiana. The following session will be held Tuesday afternoon, September 16.

TITANIUM EXTRACTION AND PROCESSING: Session IV: Process Characterization

Sponsored by: LMD Reactive Metals Committee

Program Organizers: B. Mishra, Dept. of Metall. & Matls. Eng., Colorado School of Mines, Golden, CO 80401; G.J. Kipouros, Dept. of Mining & Metall. Eng., Technical Univ. of Nova Scotia, Halifax, Nova Scotia, Canada B3J 2X4; J. Monsees, International Titanium Association, 1871 Folsom St., Suite #100, Boulder, CO 80302; S. Daniel, Oremet Titanium, 530 W. 34th Avenue, P.O. Box 580, Albany, OR 97321

Room: 203

Session Chairs: Dr. B. Mishra, Department of Metallurgical & Materials Engineering, Colorado School of Mines, Golden, CO 80401; Dr. D.L. Olson, Department of Metallurgical & Materials Engineering, Colorado School of Mines, Golden, CO 80401

TEMPERATURE DISTRIBUTION IN A KROLL BATCH REACTOR FOR TITANIUM SPONGE PRODUCTION: CH RVS Nagesh, CH Sridhar Rao, DMRL, Kanchanbagh, Hyderabad, Andhra Pradesh 500058, India; N.B. Ballal, P.K. Rao, Department of Metall. Engrng. & Matl. Sc., Indian Institute of Technology, Powai, Bombay 400 076, India

Titanium sponge is produced in batches by the magnesiothermic reduction of titanium tetrachloride at high temperature (Kroll Process). The temperature distribution within the reactor speak about the state and progress of the reduction reactions and sponge formation. The reaction temperature is controlled by suitable TiCl₄ feed rate and external cooling of the reactor. Experiments were carried out to measure the temperature distribution within the reactor by introducing TiCl₄ on a magnesium surface of 1.3m². Different TiCl₄ feed rate conditions ranging from 120-320 kg/hr.m² were used in the experiments. The experimental temperature profiles were compared with the theoretical temperature profiles determined by FEM analysis of heat conduction. The temperature data and results of thermodynamic computations carried out in the temperature range 1000-1500 K were analyzed discussed.

2:40 pm

THE DIRECT RESISTANCE ROTARY HEATING FURNACE (DRHF): L.D. Smillie, M.D. Heydenrych, Mattek- CSIR, Division of Materials Science & Technology, P.O. Box 395, Pretoria 0001, South Africa

The DRHF is a continuous gas-solid reactor which can maintain an extremely tight control on the constituents of the gas atmosphere at high temperature. With a wide field of applications such as the reduction of metal oxides, it is also suited for the low temperature regeneration of activated carbon in the gold industry. The furnace is a high temperature reactor which can operate up to 1500°C at the hot face and can be designed for very low heat losses. The DRHF is unique in that it can maintain high temperatures for endothermic reactions in a controlled gas atmosphere. The furnace contains no electrical elements to generate heat, but uses the inherent electrical properties of the material to be processed, hence the name Direct Resistance Heating Furnace.

3:05 pm

MECHANISM OF MAGNESIOTHERMIC REDUCTION OF TICl₄ BY AN ELECTRONICALLY MEDIATED REACTION (EMR): T.H. Okabe, T. Uda, E. Kasai, Y. Waseda, Research Center for Metallurgical Process Engineering, Institute of Advanced Materials Processing, Tohoku University, 2-1-1 Karahira, Aobaku, Sendai 980-77, Japan

The mechanism of magnesiothermic reduction of TiCl₄ has been discussed in the framework of electronically mediated reaction (EMR). Feed material, TiCl₄, and reductant magnesium were charged into different locations in molten MgCl₂ at 1073°K. Current flow between these feed and reductant locations was monitored when shortening these electronically isolated sites. Electrochemical potentials of each site were also measured by interrupting the current during the electronically mediated reaction. Large current, more than 5 amperes, was detected during reaction and its reproducibility was well-confirmed. This result shows titanium metal can be produced by EMR without direct physical contact between feed and reductant. Morphological characteristics and location of titanium deposition seems to depend on reaction pathway. The present results strongly suggest the concept of EMR plays an important role in the Kroll process which occurs via electron transfer through an electronically conductive medium, e.g., reactor wall and titanium deposit.

3:30 pm BREAK

3:45 pm

LOW COST PRODUCTION OF TiAl AUTOMOTIVE VALVES USING COLD WALL INDUCTION MELTING AND PERMANENT MOLD CENTRIFUGAL CASTING: A. Choudhury, M. Blum, ALD Vacuum Technologies GmbH, Rockinger Strasse 12, D- 635268 Erlensee, Germany; P. Busse, ACCESS eV., D- 52072, Aachen, Germany; D. Lupton, M. Gorywoda, W.C. Heraeus GmbH, D- 63450, Hanau, Germany

Due to the low density and high temperature strength -titanium aluminide is an excellent candidate for automotive exhaust valve applications. Lighter weight valvetrain components allow either improved performance or reduction of valve spring loads that reduce noise and friction, thereby improving fuel economy. The cost of TiAl-valves must, of course, be competitive. Existing production routes developed for aircraft industry applications are very complex and expensive and hence not appropriate for an economical mass production of TiAl-valves. For this reason, a joint project carried by three research institutes and five industrial companies along the manufacturing chain has developed a new manufacturing process under the MaTech program established by the German Federal Ministry for Research and Technology. The cost saving process consist of melting and alloying using a cold crucible furnace and centrifugal casting. In a preheated permanent mold in a single step. The new process as well as first results obtained during the running in period of the pilot plant will be presented.

4:10 pm

LEACHING OF ILMENITE WITH SULFURIC ACID BY MICROWAVE IRRADIATION: J. Peng and C. Liu, Department of Metallurgy, Kunming University of Science and Technology, Kunming, Yunnan 650093, P.R. China

4:35 pm

CHARACTERISTICS OF TEMPERATURE INCREASE OF TITANIUM MINERALS AND COMPOUNDS BY MICROWAVE IRRADIATION: J. Peng and C. Liu, Department of Metallurgy, Kunming University of Science and Technology, Kunming, Yunnan 650093, P.R. China