Recovery of thorium (IV) from leached monazite solutions using counter-current extraction

A flow sheet was developed to recover thorium from Egyptian monazite sands. The results of a detailed investigation on the extraction and stripping of thorium in the hydrous oxide are obtained after alkaline dissolution followed by leaching with alkaline carbonate solutions. This cake was dissolved in 4 M HNO₃ and thorium was extracted selectively by a counter-current extraction system using a mixer–settler contactor and Aliquat-336 in kerosene as extractant. The results show that 2 h of continuous operation are necessary to reach the steady state condition for the process. The extraction efficiency is found to be 80% and the stripping efficiency is 82%.