Removal of aluminum from chloride leach solutions of rare earths using 3-((bis(2-ethylhexyloxy))phosphoryl)-3-phenylpropanoic acid (PPPA)

The extraction and separation of Al3+ from a chloride solution of rare earths was studied using 3-((bis(2-ethylhexyloxy))phosphoryl)-3-phenylpropanoic acid (PPPA) as the extractant. The effects of factors such as initial pH value (pHini), temperature and saponification degree were investigated. The extraction is a cation exchange process deduced by the slope analysis method. Increasing the temperature facilitates the separation of aluminum from rare earths. Stripping of the loaded Al3+ can be achieved by mineral acid solutions of concentrations of 1.0 mol/L or higher. A cascade extraction process was used to remove Al3+ from a chloride liquor of the concentrate of ion-adsorption type rare earth ore. The Al3+ concentration in the aqueous solution decreased from 304.5 mg/L to 4.35 mg/L, and the recovery of rare earths was 95.6% after 5 stages of extraction and 2 stages of scrubbing.