The sustainable recovery of rare earth in the leaching solution of Baotou minerals with extraction-precipitation strategy based on fatty acids

To research and develop sustainable extraction-precipitation strategy, the recovery of rare earth (RE) was studied by using mono and binary carboxylic acids, namely lauric acid (LA), myristic acid (MA), sebacic acid (SA) and dodecanedioic acid (DA). Compared with the other carboxylic acids, LA has better precipitation performance and selectivity for RE. It was successfully used to concentrate the leaching solution of Baotou minerals to 227 g/L. RE sulfate was also transformed into RE chloride with high solubility. Ca and Mg impurities in the leachate can be effectively eliminated. The particle size of formed RE concentrate is obviously larger than that those produced by industrial precipitants, which helps to improve the separation efficiency. Unlike oxalic acid and ammonium bicarbonate, the extraction-precipitant studied in this article can be reused to avoid the generation of oxalic acid wastewater, ammonia nitrogen wastewater, and carbon dioxide. The obtained RE concentrates have good separation performances and low solubilities in aqueous phase. The mechanism of RE extraction-precipitation by LA was examined by slope analysis, XPS and IR spectra. LA showed good stability during the recovery and recycling processes. Based on the above research, the extraction-precipitation of fatty acid (FA) provides a simple, efficient and sustainable separation process for Baotou minerals.