Recovery of Rare Earth elements through chelating resin
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Estadístiques de LA Referencia / Recolecta
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hdl:2117/98411
Tipus de documentTreball Final de Grau
Data2016-06-23
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Reconeixement-NoComercial-SenseObraDerivada 3.0 Espanya
Abstract
The market of rare earths (RE); crucial elements needed in every field of industry; is currently being controlled by China since middle of the past century. China controls about 95% of global rare earths production and holds half the world reserves of RE. For years, China controlled the exportation of RE and in 2010 abruptly reduced its exportation quota creating supply disruptions. For this reason, rare-eaths elements (REE) have been considered by the EU as critical elements and it is a need to extract them from secondary sources. As secondary resources include urban wastes (e.g. fluorescent lamps, batteries, TV tubes and flat screens, etc.) and industrial (e.g. magnets) and mining wastes (e.g. mining tailings, clays, etc.). The concentration of RE in most of the secondary sources is below 1% and then recovery from such types of wastes include the combination of hydrometallurgical and pyrometallurgical processing technologies. For hydrometallurgical processing, after proper dissolution of the raw wastes with appropriate leaching solutions REE elements should be separated from transition metals (TM). REE streams then are concentrated by solvent extraction or ion-exchange as previous step to subsequent steps of separation and purification. In this study effluents collected in abandoned mines of the Odiel basin (Huelva) suffering acidmine
drainage and solid wastes generated in the on-site treatment of such effluents have been evaluated as potential secondary REE resources. Liquid samples and solid wastes have been characterized chemically and the composition on REE and transition metals has been determined. In a second stage two ion exchange resins, one containing an aminophosphonic and sulphonic acid functional groups (Purolite S957) and one containing an imino-diacetic group
(TP207) have been evaluated as potential materials for recovery of REE from moderate to strongly acidic solutions (from 0.01 to 10 M H2SO4). The capacity and the selectivity separation factors with TR metals as a function of resin dose and solution acidity have been determined using batch experiments. As a general trend REE elements are better extracted at more strong acidities than TM and when compared both resins TP207 shown higher extraction capacity than S957. Both for resins metal extraction processes are faster for S957 where after 15-30 minutes the system reached equilibrium. Contrary, the metal extraction reactions for TP207 are slower and more that 2-3 hours were needed to reach equilibrium. The, higher kinetics of S957 resins should be associated to the presence of sulfonic groups. The REE extraction had been proven to be possible with both of the resin, with upstanding result such as 100% REE extraction for resin S957 and up to 60% of REE extraction for resin TP 207. However, also TM were extracted even a very acidic solutions, and the differences found with REE are not enough to achieve the needed separation factors. The high levels of Fe and Cu in the studied samples seems to be one of the main limitations to achieve the required selectivity.
TitulacióGRAU EN ENGINYERIA EN TECNOLOGIES INDUSTRIALS (Pla 2010)
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REE_recovery.pdf | 3,088Mb | Visualitza/Obre |