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Room: Salon 8
Location: Clarion Plaza Hotel
Session Chairpersons: Renato G. Bautista, Department of Chemical and Metallurgical Engineering, University of Nevada, Reno, Reno, NV 89557; K. Osseo-Asare, Department of Materials Science and Engineering, Pennsylvania State University, University Park, PA 16802
8:30 am
SEPARATION OF RARE EARTHS, THORIUM AND URANIUM DURING MONAZITE PROCESSING BY SOLVENT EXTRACTION USING 2-ETHYL HEXYL PHOSPHONIC ACID MONO 2-ETHYL HEXYL ESTER: N.S. Narayanan, V.R. Nair, V.D. Narayanan, Indian Rare Earths, Limited, Rare Earths Div., Udyogamandal, 683 501, Kerala State, India
Monazite, one of the major sources of rare earths, is normally opened by digestion with hot concentrated caustic soda solution. Caustic digestion dissolves phosphate and leaves a hydrated mixed metal oxides cake containing thorium, uranium and rare earths. By leaching this cake with hydrochloric acid at pH 3.0 to 3.2 bulk of the rare earths are preferentially removed and separated. The slurry left after removal of major portion of rare earths contains all the thorium and uranium present in the feed monazite. In addition this slurry also contains substantial quantities of rare earths. Solvent extraction tests were carried out to develop a process to separate rare earths, thorium and uranium present in the mixed chloride solution obtained by dissolving the above slurry in hydrochloric acid.
9:00 am
PREPARATION OF DYCL3 BY DEHYDRATION IN A FLUIDIZED BED: Johan Sundström, Department of Metallurgy, Division of Process Metallurgy, The Royal Institute of Technology, S-100 44, Stockholm, Sweden.
Anhydrous DyCl3 was prepared from its hexahydrated mother-compound by batch-wise and continuous dehydration using a fluidized bed. A gas mixture of variable composition between argon and HCl was used. The productivity was high, reaching values of 0.28 mol H2O/m2xs during the dehydration to DyCl3xH2O and 0.079 mol H2O/m2xs during the dehydration to DyCl3. By using an overall reaction rate equation, developed from previous findings it was possible to predict the outcome of the continuous fluidization process. The fluidization process efficiency decreases drastically when water content is below DyCl3xO.1H2O. Therefore, in a final treatment the last traces of water were removed by slowly purging gas through a fixed bed.
9:30 am
MASS SPECTROMETRIC STUDY OF VAPORIZATION PROCESSES AND THERMODYNAMIC PROPERTIES OF DyF3-Dy2O3: V.L. Stolyarova, S. Seetharaman, The Royal Institute of Technology, S-100 44, Stockholm, Sweden
In the present work the vaporization processes and thermodynamic properties of the DyF3-Dy2O3 system were studied at the temperatures 1173-1423 K in the concentration range from the individual DyF3 to the individual Dy2 by the Knudsen effusion mass spectrometric method. It was found, the DyF3, DyOF, Dy2OF4 molecules were the main species in vapour. The DyF3 activity in the DyF3-Dy2O3 system was calculated by comparing the total ion currents of dysprosium triufluoride over the system and the individual component. The influence of the cell material (Pt, Mo, Ta) on the concentration of the DyF3, DyOF, Dy2OF4 vapour species in the gaseous phase over the DyF3-Dy2O3 was illustrated. Results, obtained in the present study are in agreement with the available information on the phase diagram of the DyF3-Dy2O3 system.
10:00 am BREAK
10:30 am
PRECIPITATION PROCESSES IN THE SEPARATION OF RARE EARTHS: K. Osseo-Asare, Department of Materials Science and Engineering, Pennsylvania, State University, University Park, PA 16802
Abstract not available.
11:00 am
Nd2Fe14B/
-Fe BASED NANOCOMPOSITE PERMANENT MAGNET MATERIALS PREPARED VIAL MECHANICAL MILLING: W.F. Miao, P.G. McCormick, R. Street, Research Centre for Advanced Mineral and Materials Processing, The University of Western Australia, Nedlands, W.A. 6907, Australia
Nanocrystalline mixtures of Nd2Fe14B and -Fe have been synthesized by mechanical milling and heat treatment. The samples exhibit isotropic magnetic behaviour, with significant remenence enhancement associated with exchange coupling across the interfaces of hard and soft magnetic phases. Magnetic Phases. Magnetic properties are found to depend on the volume fraction of the -Fe phase and heat treatment. The effect of alloy additions to increase the saturation magnetization of the soft phase and the magnetocrystalline anisotropy of the hard phase has also been investigated.
11:30 am
NOVEL TECHNIQUE FOR THE PREPARATION OF SINTERED YBCO: M.I. Hussain, F A. Khwaja, Mazhar Hussain, Anwar-Ul-Haque, Department of Physics, Quaid-I-Azam University, Islamabad, Pakistan., Department of Chemistry, Quaid-I-Azam University, Islamabad, Pakistan
We report on the preparation of YBCO sintered sample by a novel technique named "Explosion Method". The stoichiometric ratio of the compounds were mixed and the powder was encapsulated in the quartz tube. The capsule exploded at 16-hours for specific mass of the product and the size of the tube. The powder was pelletized and characteristic properties were checked. The detailed investigation is carried out on the mass of the product and the size of the capsule which plays an important role in the preparation of superconducting phase, in this method. It has been observed that explosion is important for the superconductivity. The absence of annealing is an advantage in this process, however, the sample deteriorate with time.
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