Combined extraction of rare metals Ga-Nb-REE from the fly ash
LIU Huidong1, TIAN Heming2, ZOU Jianhua2
1. College of Geoscience and Surveying Engineering, China University of Mining and Technology, Beijing 100083, China;
2. Chongqing Institute of Geology and Mineral Resources, Chongqing 400000, China
Abstract：Alkali sintering-multistep leaching experiments are carried out to extract the rare metals Ga, Nb and REE (rare earth elements) from the fly ash in the circulating fluidized bed (CFB) generated from the Anwen Coal-fired Power Plant in Chongqing, Southwest China. It is shown that, the roasting of the CFB fly ash with 1.5 times Na2CO3 under 860℃ for 30 minutes, followed by the water leaching (Solid/Liquid (S/L)=1:10; 90℃; 2 hours) extraction of Ga and the acid leaching (HCl solution, 6 mol/L; S/L= 1:20; 60℃; 2 hours) extraction of REE, can achieve extraction rates of 84.70% and 80.07% for Ga and REE, respectively. The leaching rate of Niobium (Nb) enriched in the acid leaching residue, is lower than 1% in the above two steps. Adsorption and desorption experiments of Gallium from the Ga-rich water leaching filtrate using the D201 ion exchange resin and NH4Cl solution (0.5 mol/L) are carried out both under a temperature of 40℃. The adsorption rate (27.99%) and the desorption rate (37.33%) of Ga are unsatisfactory. The conditions of the follow-up experiments would be adjusted in order to enhance the separation and extraction effect of Ga. The extraction process of Nb from the acid leaching residue and the separation of REE from the acid leaching solution also need to be further studied. With the above combined extraction technology for Ga, Nb, REE and subsequent studies, a high value-added fly ash product is expected. The environmental pollution pressure caused by the Anwen fly ash might be alleviated.
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2015, Vol. 33 
