Technology for Deep Purification of Cesium Iodide Single Crystal Production Wastes from Heavy Metals

1Grinyov, BV  https://orcid.org/0000-0003-1700-0173
1Cherginets, VL  https://orcid.org/0000-0002-2308-8979
1Rebrova, TP
1Ponomarenko, TV
1Varich, AG
1Rebrov, OL
1Institute for Scintillation Materials, NAS of Ukraine
Sci. innov. 2020, 16(1):45-53
https://doi.org/10.15407/scine16.01.045
Section: Research and Engineering Innovative Projects of the National Academy of Sciences of Ukraine
Language: English
Abstract: 
Introduction. The production of CsI-based scintillation crystals results in accumulation of wastes formed during the crystal growth and as a result of the mechanical treatment. Therefore, thorough purification from heavy metals is the main condition of CsI recycling for the further application in obtaining the different activated single crystals.
Problem Statement. Thallium is one of the main admixtures in the wastes of CsI-based crystal production because it is used as an activating admixture for the of CsI:Tl crystals. Since Tl is referred to heavy metals which are hardly removable from the wastes of CsI crystal production the development of the purification technology of technogenic CsI solution from admixtures of heavy metals is necessary.
Purpose. The development of technology providing purification of the wastes of CsI-based crystal production to the level required by national normative documentation for extra pure CsI.
Materials and Methods. Materials: the liquid wastes of CsI-based crystal production (the CsI solution), activated carbon, metallic magnesium, barium hydroxide, cesium carbonate. Methods: the treatment of mixture of the heated CsI solution with the purifier by stirring, the multiple filtering of the heated CsI through the cartridge filters filled with purifying reagents.
Results. The method for treatment of technogenic CsI solution with magnesium at heating and stirring proved to be successful under laboratory conditions, however, attempts to level it up for the industrial scale failed. Multiple filtering of the heated reagent mixture through the cartridge filters filled with purifying reagents proved to be better and led to successful industrial examinations. It gives the possibility to obtain the extra pure product, CsI, meeting requirements of TU U 24.13.31331736-002-2004 for cesium iodide.
Conclusions. A new technology for deep purifying the wastes of CsI-based crystal production from heavy metals including thallium has been developed.
Keywords: cesium iodide, heavy metals, magnesium, purification, technogenic solution
References: 
1. Efimov, A. I., Belorukova, L. P., Vasil’kova, I. V., Chechev, V. P. (1983). Properties of inorganic compounds. Leningrad: Khimiya [In Russian]. 
2. Cherginets, V. L., Ponomarenko, T. V., Rebrova, T. P., Varich, A. G., Rebrov, A. L., Datsko, Yu. N. (2018). On the features of crystallization methods used for the purification of aqueous solutions of cesium iodide. Functional Materials, 25(3), 594–600.
https://doi.org/10.15407/fm25.03.594
3. Goronovskiy, I. T., Nazarenko, Yu. P., Nekryach, E. F. (1987). Short handbook on chemistry. Kiev : Naukova dumka [In Russian].
4. Cesium iodide of extra pure quality for single crystals / Technical conditions TU U24.13.31331736 – 002 – 2004, 2004.
5. Ryznar, J. W., Green, J., Winterstein, M. G. (1946). Determination of the pH of saturation of magnesium hydroxide. Ind. Eng. Chem., 38(10), 1057–1061.
https://doi.org/10.1021/ie50442a023