On 2 September 2026 at 14.15 Andrei Goronovski will defend his doctoral thesis “Systematic study and NORM-LCA methodology development of NORM aspects in the bauxite residue valorization chain” .
Supervisor:
Associate Professor Alan Henry Tkaczyk, Faculty of Science and Technology, University of Tartu, Estonia
Opponent:
Professor Wouter Schroeyers, Faculty of Engineering Technology, Hasselt University, Belgium
Summary
Historically, risks arising from Naturally Occurring Radioactive Materials (NORM) have been overlooked not only in the Life Cycle Assessment (LCA) methodology, but also in mineral processing industries resulting in unnecessary exposure to ionizing radiation to workers, public and environment. However, NORM pose same health threats as artificial radionuclides. To address this, two primary goals were achieved: (1) incorporation of a NORM impact category within the LCA methodology and (2) characterization of bauxite residue (BR) valorization streams from a radiological perspective. The newly developed NORM-LCA impact category covers considerable risks to human health that have been historically overlooked. The model demonstra₃ted that radiological impact from natural radionuclides contained in conventional construction materials provide highest damage to people compared to existing LCA impact categories. However, the impact from incorporating BR into construction materials would be minor compared to conventional materials, as these already contain significant quantities of natural radionuclides. It was demonstrated that multi-stage valorization processes of BR can be achieved without significant radionuclide accumulation in secondary residues. It was confirmed that radioactivity concentrations in materials resulting from BR valorization would be too low to pose a health threat. This is explained by the addition of diluting materials and the co-recovery of radionuclides with valuable metals during processes like reduction roasting, acidic leaching, and ionic liquid leaching. The study observed that equilibrium decay chains of natural uranium and thorium can be broken during chemical and metallurgical treatment, with isotopes from a single chain ending up in different process streams (e.g., ²³⁸U dissolving while ²²⁶Ra remains solid in the Bayer process). This resulted in a co-recovery of some natural radionuclides making further studies necessary to confirm worker safety considering also recovered valuable metals. In summary, this research demonstrated importance of NORM-LCA model for conventional and future construction materials and confirmed that from a radiological standpoint, BR valorization can be achieved without significant health threats.
