REDMUD - European Training Network for Zero-Waste Valorisation of Bauxite Residue (Red Mud)

Selle kollektsiooni püsiv URIhttps://hdl.handle.net/10062/66669

To tackle its (critical) raw material dependency, Europe needs comprehensive strategies based on sustainable primary mining, substitution and recycling. Freshly produced flows and stocks of landfilled industrial residues such as mine tailings, non-ferrous slag and bauxite residue (BR) can provide major amounts of critical metals and, concurrently, minerals for low-carbon building materials. The European Training Network for Zero-Waste Valorisation of Bauxite Residue (REDMUD) therefore targets the vast streams of new and stockpiled BR in the EU-28. BR contains several critical metals, is associated with a substantial management cost, whereas spills have led to major environmental incidents, including the Ajka disaster in Hungary. To date, zero-waste valorisation of BR is not occurring yet. The creation of a zero-waste BR valorisation industry in Europe urgently requires skilled scientists and engineers, who can tackle the barriers to develop fully closed-loop environmentally-friendly recovery flow sheets. REDMUD trains 15 researchers in the S/T of bauxite residue valorisation, with emphasis on the recovery of Fe, Al, Ti and rare earths (incl. Sc) while valorising the residuals into building materials. An intersectoral and interdisciplinary collaboration of EU-leading institutes and scientists has been established, which covers the full value chain, from BR to recovered metals and new building materials. Research challenges include the development of efficient extraction of Fe, Al, Ti and rare earths (incl. Sc) from distinct (NORM classified) BRs and the preparation of new building materials with higher than usual Fe content. By training the researchers in pyro-, hydro- and ionometallurgy, electrolysis, rare-earth extraction and separation technology, inorganic polymer and cement chemistry, Life Cycle Assessment (LCA), NORM aspects and characterisation, they become the much needed scientists and engineers for the growing European critical raw materials industry.

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Incorporating the radiological effects and environmental impact assessment of naturally occurring radioactive materials (NORM) into the life cycle environmental optimisation of bauxite residue (BR) valorisation
(Bauxite Residue Valorisation and Best Practices, 2015-10) Joyce, Peter James; Goronovski, Andrei; Tkaczyk, Alan Henry; Björklund, Anna
Bauxite Residue (BR) is a potentially valuable source of metals and construction materials, which the ETN REDMUD project aims to develop technologies to exploit. Bauxite contains low levels of Naturally Occurring Radioactive Materials (NORM), which are concentrated in BR, and could potentially be released during BR valorisation, or further concentrated in novel products resulting from BR valorisation. Life Cycle Assessment (LCA) is a well-established and standardised methodology to quantify the potential impacts arising from the life cycle of products and services, however it is not currently possible use it to assess the radiological impacts of NORM. The inclusion of NORM exposure in LCA is an important step to avoid burden shifting in the environmental optimisation of BR valorisation.
A framework for including enhanced exposure to naturally occurring radioactive materials (NORM) in LCA
(The International Journal of Life Cycle Assessment, 2016-11-22) Joyce, Peter James; Goronovski, Andrei; Tkaczyk, Alan Henry; Björklund, Anna
Despite advances in the development of impact categories for ionising radiation, the focus on artificial radionuclides produced in the nuclear fuel cycle means that the potential impacts resulting from increased exposure to naturally occurring radioactive materials (NORM) are still only covered to a limited degree in life cycle assessment (LCA). Here, we present a potential framework for the inclusion of the exposure routes and impact pathways particular to NORM in LCA.
Radiological assessment of the Bayer process
(Minerals Engineering, 2019-04-13) Goronovski, Andrei; Vind, Johannes; Vassiliadou, Vicky; Panias, Dimitrios; Tkaczyk, Alan Henry
Naturally occurring radionuclides were studied through the Bayer process by calculating their mass flows. Aluminium of Greece (AoG) provided sample materials and plant data from several process stages. Measurements of radionuclide concentrations were carried out by gamma-ray spectroscopy. The performed measurements show that in the specific case of the AoG plant, the majority of the natural radionuclides were introduced with karst bauxites, which showed higher activity concentrations for nuclides compared to lateritic bauxites. Most of these nuclides accumulated in the bauxite residue, while only a minor portion of uranium isotope 238U was found in alumina, corresponding to 3% of its input value. Uranium was observed to partially dissolve in the process liquors similarly to 40K, whereas the latter was not associated with aluminium hydroxide. All the materials studied in the current research work had radionuclide concentrations well below the exemption limits set by EURATOM Basic Safety Standard, indicating that these naturally occurring radionuclides do not pose a radiological hazard for workers of the AoG plant or the public.
Radiological Assessment of the Bauxite Residue Valorization Chain
(Journal of Radioanalytical and Nuclear Chemistry, 2019-07-27) Goronovski, Andrei; Tkaczyk, Alan Henry
The behavior of radionuclides in the bauxite residue valorization chain has been analyzed, and accumulation ratios have been measured for secondary residues produced after recovery of valuable metals. Key analysis outcomes are valid specifically for the processes and raw materials in use at the Aluminium of Greece plant and are as follows: the processing of bauxite residue from the is unlikely to create secondary residues that would be hazardous from the radiological perspective, even if bauxite residue is processed successively multiple times to recover different metals. From a radiological perspective, there are no considerable limitations for the exploitation of specific BR for metal recovery. As some conclusions may be raw material or process dependent, future research could assess the possibility of applying these outcomes to other bauxite plants.
IMPACT ASSESSMENT OF ENHANCED EXPOSURE FROM NATURALLY OCCURRING RADIOACTIVE MATERIALS (NORM) WITHIN LCA
(Journal of Cleaner Production, 2018-01-20) Goronovski, Andrei; Joyce, Peter James; Finnveden, Göran; Tkaczyk, Alan Henry; Björklund, Anna
The potential impact of ionising radiation from enhanced exposure to Naturally Occurring Radioactive Materials (NORM) to humans and the environment is not currently accounted for sufficiently in Life Cycle Assessment (LCA). Here we present midpoint and endpoint characterisation factors resulting from the implementation of impact assessment models for human health and ecosystems for NORM exposure. These models build upon existing fate, exposure and effect models from the LCA and radiological literature. The newly developed models are applied to a theoretical study of the utilisation of bauxite residue, a by-product of alumina processing enriched in natural radionuclides, in building materials. The ecosystem models have significant sensitivity to uncertainties surrounding the differential environmental fate of parent and daughter radionuclides that are produced as a part of decay chains, and to assumptions regarding long term releases from landfill sites. However, conservative results for environmental exposure suggest that in addition to landfill of materials, power consumption (burning coal and mining uranium) is a potentially significant source of radiological impact to the environment. From a human perspective, exposure to NORM in the use phase of building materials is the dominant source of impact, with environmental releases of nuclides playing a comparatively minor role. At an endpoint level, the impact of NORM exposure is highly significant in comparison to other impact categories in the area of protection of human health. This highlights the importance within LCA of having sufficient impact assessment models to capture all potential impacts, such that issues of burden shifting between impact measures can be captured, interpreted and resolved in the optimisation of product systems.
Assessment of NORM in bauxite residue to facilitate valorization
(2nd Bauxite Residue Valorisation and Best Practices Conference, 2018) Goronovski, Andrei; Tkaczyk, Alan H.
In the new Euratom Basic Safety Standard (BSS), materials with elevated concentrations of natural radionuclides can be considered as a potential source of radiological exposure. Such materials are often found in mining and metal extractive industries, where natural radionuclides are likely to end up and accumulate in the residue streams. Radiological assessment of the produced residues is a first and often sufficient step to demonstrate worker safety against radiological exposure. Bauxite Residue (BR) is an example of a material which has an elevated natural radionuclide concentration. BR used in this work is coming from Greece and was assessed to be below the BSS reference levels and therefore does not pose a significant risk of elevated radiological exposure. The processing of BR might result in further radionuclide accumulation in secondary residues, which also should be characterized to demonstrate the radiological safety of workers. In this work, the radiological properties of the residues produced after applying different extractive techniques for the recovery of iron, alumina and Rare Earth Elements (REE) were examined. All the analyzed samples were produced at the laboratory scale. The results suggest that for these residues, there is no significant radionuclide accumulation which would cause potentially elevated radiological exposure.
Distribution of uranium, thorium and potassium in the Bayer process
(2nd Bauxite Residue Valorisation and Best Practices Conference, 2018) Goronovski, Andrei; Vind, Johannes; Vassiliadou, Vicky; Panias, Dimitrios; Tkaczyk, Alan Henry
Uranium, thorium, potassium and their decay product mass flows were analysed in the Bayer process. Gamma-ray spectroscopy was used to measure the radionuclide content in samples provided by Aluminium of Greece and to model their mass flows. We observed that at any analysed stage, the radionuclide content does not exceed the allowed safety limits set in the European Basic Safety Standard. Another important observation is that a minor portion of uranium from bauxites (3%) ends up in alumina, while the rest is accumulated in the bauxite residue (BR). All of the 226Ra (long-lived decay product of uranium), as well as all decay products of thorium accumulated in the BR. We observed accumulation of 40K in the process liquors, while this radionuclide was not found in the alumina.

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