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Titre : | Les terres rares dans les bauxites |
Auteurs : | Lucie POTIER |
Type de document : | Projet d'initiation à la recherche apprenti |
Concepts : |
KAOLINITE
SAMARIUM TERRES RARES MINERAI ALUMINE NEODYME ENVIRONNEMENT |
Résumé : | During the study conducted during this project of initiation to research, various points on bauxites and rare earths were discussed. The studies presented were conducted using samples from China, Italy, Iran and France. A first stage of bibliographic research made it possible to clearly define the main types of bauxites: lateritic, karst and sedimentary, as well as their principles of formation from aluminosilicate source rocks. However, several hypotheses proposing other classification models of bauxite are still being debated. The formation environment is generally tropical with a very developed water alteration, as well as a possible transport according to the type of bauxite. The bedrock is largely related to the final mineralogy of bauxite, so the composition of bauxites can be very varied. The phenomena of redox and leaching of mobile elements are responsible for the formation of large amounts of aluminous minerals in these rocks. These minerals are used in the alumina industry. However, their treatment leads to a significant formation of residues: red mud. Recent studies on the composition of these residues have made it possible to identify the presence of rare earths as well as the possibilities of extracting them. Thus, different extraction techniques have been developed to maximize the potential of rare earths. A second step will have made it possible to identify which rare earths are present in bauxite, their characteristics and the usefulness of their extraction. The geochemical analyzes collected in three of the study countries show particularly interesting results. The lateritization rate is higher in the case of lateritic bauxites, and the presence of silica is very low in this case. The concentration of rare earths, as well as anomalies in cerium and europium, could be noted, and associated with the types of bauxite. |
Spécialité : | Géologie |
Numéro de promo : | 80 |
numéro MIR : | 011 |