Separation, purification and recovery of thorium from monazite leach liquors by counter-current extraction process

Abstract

Separation and purification of thorium from monazite leach liquors was investigated by counter current extraction process. The Primene JM-T (mixture of highly branched C16 to C22 tertiary alkyl primary amine isomers) was used as an extractant and kerosene as a diluent for the present investigation. Extraction isotherm was plotted at the condition: 0.1 mol/L Primene JM-T, A:O = 3:1, which predicted on requirement of 3 stages for quantitative extraction of thorium. A 99.9% extraction of thorium from the leach liquor was achieved at the optimum conditions leaving 0.1 mg/L of the metal in the raffinate phase. The predicted three counter current stripping stages from the stripping were validated using 0.5 mol/L HCl + 0.5 mol/L NH4Cl as the stripping agent. XRD analysis proved the high purity thorium oxalate precipitated and recovered from monazite.