Preparation of Nd(III) carbonate by precipitation stripping of Nd(III)-loaded VA10
- PDF / 277,978 Bytes
- 9 Pages / 612 x 792 pts (letter) Page_size
- 25 Downloads / 180 Views
I. INTRODUCTION
RARE-EARTH elements have similar properties, and, thus, their separation in pure form is extremely difficult. However, recent developments in ion-exchange and solvent extraction technology have shed new light on how to separate these elements. Rare-earth elements are now widely utilized as functional materials.[1] For example, neodymium is extensively used in permanent magnets with high coercive force and in fluorescent lamps.[2] To develop functional materials of better quality, the use of novel purification technology or precise control of physical properties, such as particle shape and size, is necessary.[3] To this end, solvent extraction appears to be a very promising method. Generally, separation of metal ions by solvent extraction can be achieved in the extraction as well as in the stripping step. For example, if we add a precipitating agent to stripping solution, we often directly recover desired metal ions as chemical compounds. This method is known as precipitation stripping (or crystallization stripping),[4,5] and is suitable for obtaining fine particles. It has been reported that metal ions, such as Ag(I), Cu(II), Co(II), Ni(II), etc. can be stripped as carbonates under pressure with carbon dioxide gas, and sintered products of these carbonates are generally fine powders.[6,7,8] In a series of studies, Sano et al.[8] reported that crystalline Nd2(CO3)3?8H2O can be SUMIKO SANUKI, Associate Professor, Department of Material Systems Engineering and Life Science, and KATSUHIRO MATSUSHITA, Student, and MOTOYA NISHIWAKI, Graduate Student, Department of Materials Science and Engineering, are with the Faculty of Engineering, Toyama University, 930-8555 Toyama City, Japan. HIROSHI MAJIMA, Professor Emeritus, Kyoto University, 606-8501 Kyoto City, Japan, is Special Advisor, Titan Kogyo K.K., 755-8567 Ube City, Japan. Manuscript submitted June 26, 1998. METALLURGICAL AND MATERIALS TRANSACTIONS B
recovered from Nd(III)-loaded versatic acid 10 (VA10) using water as a stripping solution. However, they did not present data in any detail. The solubility of carbonates of lanthanide elements is generally small, e.g. the solubility product of Nd2(CO3)3 is 1.0 3 10233,[9] thus, the possibility exists of precipitation stripping of carbonates of rare-earth metals under normal pressure. In the present study, the possibility of precipitation stripping of Nd(III) carbonate from an organic phase containing Nd(III)-loaded VA10, using carbon dioxide gas under normal pressure, was examined. The possibility of precipitation stripping of Nd(III) carbonate using NH32(NH4)2CO3 acting as a CO22 3 ion source under highly alkaline conditions was also investigated. Furthermore, the transfer of VA10 from an aqueous to an organic phase through evaporation of NH3 from stripping solution was studied, since VA10 easily dissolves in a stripping solution that is highly alkaline. This type of work is particularly important for regeneration and recycling of extractant. II. EXPERIMENTAL PROCEDURES A. Samples Used The extractant use
Data Loading...
