MATERIALS SYNTHESIS AND CHARACTERIZATION FOR WASTE VALORIZATION AND NUCLEAR WASTE CONTAINMENT
| Autor: | Bollinger, David L |
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| Jazyk: | angličtina |
| Rok vydání: | 2023 |
| Předmět: | |
| DOI: | 10.7273/000004582 |
| Popis: | Waste valorization is the process of converting a waste material into something of value. In this work, waste valorization was explored in the context of mining and refinery wastes, nuclear waste disposal, and sustainable cement production. Methods and techniques developed in the course of the work on each material were applicable to work on the others.Bauxite residue is the caustic byproduct of refining bauxite ore via the Bayer process. There are billions of tons of legacy bauxite residues in waste lagoons around the world and hundreds of millions of tons produced yearly. One component of bauxite residue is desilication product, which is comprised of the aluminosilicate minerals sodalite and cancrinite. Acting as a pH buffer and sodium reservoir, desilication product stands in the way of easy remediation of bauxite residues. Work here focused on transforming these caged silicates into layered clay minerals, whose cation exchange and water storage properties would make them valuable soil amendments. While full conversion to clays was not achieved, results suggest that proto-clay mineraloids may have been created, which can guide the way to continued work on clay synthesis from desilication product. The caged structures of sodalites and cancrinites can flexibly accommodate a wide variety of anions, which has made these minerals the focus of research into radioisotope immobilization. Building on the synthesis and characterization techniques developed for bauxite residue remediation, research continued into the ability of sodalites and cancrinites to incorporate mixed anion wastes, with a particular interest in capturing iodide, a non-radioactive analogue of iodine-129. Mixed anion sodalites were shown to be successfully prepared from a caustic slurry of iodide and other anions. Post-synthesis treatment options were explored to reduce secondary waste streams, water use, and improve waste form durability. Furthermore, construction and demolition wastes were investigated for their viability as waste valorized cement additives. The X-ray diffraction techniques developed in the course of bauxite residue and caustic scrubber research were further refined and applied to the analysis of these sustainable cements. These techniques enabled significant automation of Rietveld analysis and led to improved, lower-error phase composition results. |
| Databáze: | OpenAIRE |
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