Extraction of samarium and gadolinium from aqueous nitrate solution with D2EHPA in a pulsed disc and doughnut column

• The effect of operating parameters on the gadolinium and samarium extraction was investigated.
• Batch studies were carried out for selecting the pH, D2EHPA concentration and stripping acid.
• A comparative evaluation of empirical correlations used to predict drop sizes and holdup.
• The feasibility of pulsed disc and doughnut extraction columns for rare earths was investigated.

The extraction of samarium and gadolinium from aqueous nitrate solution with D2EHPA using a pulsed disc and doughnut column was investigated. It was found from batch experiments for separation of Sm(III) from Gd(III) that the initial aqueous pH, concentration of D2EHPA and concentration of nitric acid as a stripping agent were optimized at 1.5, 0.12 M, and 0.1 M, respectively. In continuous experiments, the effects of variables such as pulsation intensity, dispersed and continuous phase velocity on holdup, mean drop sizes, separation factors and stripping efficiencies were studied. Empirical correlations for prediction of the dispersed phase holdup and mean drop sizes in terms of the operating variables and the physical properties were compared with the experimental results. The results of the continuous experiments demonstrated the feasibility of operating extraction process in the pulsed disc and doughnut column, with good efficiency for separation of samarium from gadolinium in the extraction and stripping stages.

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