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[Master 2/1] Treatment of organic matter contained in industrial wastes : pyrochemical approach

par Anne-Laure Rollet - 20 décembre 2019

Période de stage : janvier 2020 - juin 2020 (6 months)

contact : ana-gabriela.porras-gutierrez ad ; anne-laure.rollet ad

niveau / compétence  : M2 - M1 / physico-chimiste


The radioactive wastes coming from nuclear industry can be difficult to treat, complex and/or expensive systems are usually required to safely and effectively destroy the wastes. In a quest to optimize waste management, Orano is constantly looking for nuclear operators safe and optimized solutions for packaging, transporting and/or storing all categories of wastes. This approach is based on a constant improvement of the processes used and on the development of new techniques in relation with university laboratories. Thus, Orano, PHENIX laboratory (Sorbonne Université) and LR4CU laboratory (Université de Lille) established a collaboration with the aim of evaluating a methodology based on pyrochemistry in molten salts to treat industrial low radioactive nuclear wastes containing organic material. Molten salts could offer significant advantages as compared to the pyrometallurgical and could lead to significant breakthrough in the field. Molten salt is a robust thermal treatment process that can be used to oxidatively and efficiently destroy the organic constituents of mixed and hazardous wastes, and energetic material, retaining inorganic and radioactive constituents in the salt [1]. Depending on the chemical nature of molten salt has several functions. (1) It acts as a dispersion medium for both the waste being processed and air. (2) It can oxidize organic matter as in the case of molten carbonates, where oxygen dissolves chemically forming peroxide and superoxide ions which are strong oxidizing agent. (3) It can capture most of the ash, radionucleides, heavy metals and other non-combustible materials associated with the waste. For instance, acidic species such as F, Cl, Br, I, S, and P in the wastes react with molten carbonate forming corresponding neutralized salts. Some metals in the waste can also react with salt and oxygen forming metal oxides or salts. These insoluble metal oxides and salts are commonly referred to as ash [2,3]. Previous work, carried out in both laboratories, showed that organic material (polyethylene, neoprene, and isoprene) can be degraded in several simple oxidizing molten salts. The next step is to evaluate the possibility of combining the properties these salts in complex mixtures to decompose organic material. However, few studies are devoted to such systems and no experimental data are available. The purpose of this project is firstly to determine the phase diagram of several promising oxidizing molten salts and secondly to test the efficiency of these molten salts for the destruction of organic matter.

2. Techniques ou méthodes utilisées / Specific techniques or methods

Engineering process X Ray Diffractometry (XRD) Thermogravimetric analysis (TGA) Analytical methods such as GC-MS Energy-dispersive X-ray spectroscopy

3. Références / References 1. P. Kovařík, J. D. Navratil and J. John, Sci. Technol. Nucl. Install., (2015)1. 2. Z. Yao, J. Li and X. Zhao, Chemosphere, 2011, 84, 1167–1174. 3. J. Stimmel,R.Wishau, K. B. Ramsey,A.Montoya,J.Brock, and M. Heslop, in Proceedings of the Waste Management ’99 symposium (WM ’99), Tucson, Ariz, USA, February-March 1999