POLYMERS MODIFIED CLAYS FOR SEPARATING RARE EARTHS FROM WEEE

Today there is an increasing need for Rare Earths (REs) due to their usage in numerous high-technology applications. Each of these applications requires specific RE elements and they are not all interchangeable. Increasing demand for the different products containing REs has resulted in a restriction of supply from producing Countries, particularly China, which currently produces 97% of the world’s REs. This constriction of supply is being met by the development of many new REs mining projects which are characterized, however, by technical, economic and environmental problems (Binnemans et al., 2013). Currently each EU citizen produces about 17 kg of Waste Electric and Electronic Equipment (WEEE) per year. According to European Union estimates, this value is expected to rise to 24 kg by 2020. These wastes are rich in precious and strategic metals and, in many cases, are characterized by higher REs contents than those of natural minerals. Accordingly, recycling can be considered a valuable opportunity. This perspective, known as "urban mining," bases on the development of "Best Practices" for collection, transportation, recycling and recovery of precious metals and REs from WEEE, so as to transform the waste into an economic value product and, at the same time, so as to minimize the environmental impact. This approach can reduce the supply risk of such raw materials, strategic for a lot of important manufacturing industries, and it can provide to small and medium enterprises the possibility of low time and relatively low cost of reconversion. For these reasons, the study of a targeted and efficient REs recovery from WEEE can only lead to undeniable both socio-economic and environmental benefits (Iannicelli Zubiani et al., 2012). Recycling of WEEE and recovering of metals can be divided into three steps: disassembly, upgrading and refining. In this last step, recovered metals are melted or dissolved by using pyrometallurgical, hydrometallurgical or biometallurgical processing. In the field of hydrometallurgy, several separation technologies have been extensively adapted for the recovery of metal ions from aqueous solution. Among them, Solid-Phase Extraction (SPE) presents some advantages: high recovery, short extraction time, high enrichment factor, low cost and low consumption of organic solvents (Li et al., 2011). In particular, clays as solid-phase are characterized by some outstanding advantages, such as low cost, high mechanical intensity, good acid tolerance, convenient solid-liquid separation and excellent reusability.