Pure Scandium Production
Development of the Technology to Obtain Pure Metal Scandium by Thermal Decomposition of Scandium Iodide
Tech Area / Field
- MAT-ALL/High Performance Metals and Alloys/Materials
- CHE-IND/Industrial Chemistry and Chemical Process Engineering/Chemistry
8 Project completed
Senior Project Manager
Zalouzhny A A
VNIIEF, Russia, N. Novgorod reg., Sarov
- All-Russian Scientific Research Institute of Non-Organic Materials named after A. Bochvar, Russia, Moscow
Project summaryThe project being proposed refers to development of the technology of pure metal scandium obtaining by thermal decomposition of scandium iodide. The processes of refining of rare metals (titanium, zirconium, thorium and others) are widely implemented for preparation of compact metals featuring high purity.
The resulting from the above processes so called iodide metals are more pure than the industrial products obtained by any other method.
Usually the processes of iodide refining are used for purification of small rare metal quantities. One of the provisions for iodide refining referred to as necessary is interaction of relatively low-grade metal (raw material for obtaining of iodide metal) with iodine vapors at relatively law temperature with formation of sufficiently volatile rare metal iodide. The resulting metal iodide is then subjected to thermal decomposition, as a rule, at a metal wire or filament, heated by electric current, the wire or filament being manufactured from the refined metal itself or from tungsten or molybdenum.
The first industrial methods of iodide refining were used for obtaining of iodide titanium or iodide zirconium by the following schemes:
TiI4« Ti + 2I2 and ZrI4 « Zr + 2I2
Iodide refining was also used for obtaining of thorium, uranium and vanadium. The attempt to obtain iodide beryllium by the same method was less successful.
The data on laboratory method of metal scandium obtaining by thermal decomposition of anhydrous scandium iodide are absent in scientific-technical literature. Thermodynamic and kinetic parameters of scandium triiodide thermal decomposition at different temperatures are also unknown. This is a serious gap in the theory and practice of development of the technology for scandium metal refining.
It should be noted that the scientific-technical literature describes different traditional methods of refining the scandium initial metal and rare-earth metals: vacuum sublimation, vacuum melting, zone re-crystallization (zone melting), electric transfer in solid state, electric refining in melted salts. Each of these methods has its own advantages and shortcomings. Pure scandium metal obtaining by thermal decomposition of scandium triiodide can be achieved by the following dissociation reaction:
2ScI3(vapor) « 2Sc(solid) + 3I2(vapor)
However, the advantages and limitations of iodide method of scandium refining can not be estimated even approximately due to the complete absence of empiric data on the processes accompanying iodide scandium obtaining from the initial metal.
The present project aims at development of laboratory-scale technology for obtaining of iodide scandium. In the course of project execution it is foreseen to find out the potentials and the objective limitations of iodide scandium laboratory preparation technology. The estimated result of project-related development is creation of the laboratory technology of iodide scandium obtaining, as well as defining of competitiveness of the iodide method of scandium refining if compared to the traditional methods of refining this rare and dispersed metal.