Calculation of Light to Medium Rare Earth Solvent Extraction Processes Optimal Extraction Ratio Theory

Solvent extraction is the most widely used method for separation and purification of rare earth elements, and organic extractants such as di(2-ethylhexyl) phosphoric acid (P204) and di(1-methyl-heptyl) methyl phosphonate (P350) are most commonly used for industrial applications. However, the presence of impurity ions in the feed liquid during extraction can easily emulsify the extractant and affect the quality of rare earth products. Aluminum ion is the most common impurity ion in the feed liquid, and it is an important cause of emulsification of the extractant. In this study, the influence of aluminum ion was investigated on the extraction of light rare earth elements by the P204-P350 system in hydrochloric acid medium. The results show that Al3+ competes with light rare earths in the extraction process, reducing the overall extraction rate. In addition, the Al3+ stripping rate is low and there is continuous accumulation of Al3+ in the organic phase during the stripping process, affecting the extraction efficiency and even causing emulsification. The slope method and infrared detection were utilized to explore the formation of an extraction compound of Al3+ and the extractant P204-P350 that entered the organic phase as AlCl[(HA)2]2P350(o).

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Two-Step Solvent Extraction of Radioactive Elements and Rare Earths from Estonian Phosphorite Ore Using Nitrated Aliquat 336 and Bis(2-ethylhexyl) Phosphate

Minerals ◽

10.3390/min11040388 ◽

2021 ◽

Vol 11 (4) ◽

pp. 388

Author(s):

Silvester Jürjo ◽

Liis Siinor ◽

Carolin Siimenson ◽

Päärn Paiste ◽

Enn Lust

Keyword(s):

Rare Earth ◽

Solvent Extraction ◽

Rare Earth Elements ◽

Toxic Elements ◽

Downstream Processing ◽

Liquid Extraction ◽

Aliquat 336 ◽

Radioactive Elements ◽

Improved Method ◽

Ph Values

Estonian phosphorite ore contains trace amounts of rare earth elements (REEs), many other d-metals, and some radioactive elements. Rare earth elements, Mo, V, etc. might be economically exploitable, while some radioactive and toxic elements should be removed before any other downstream processing for environmental and nutritional safety reasons. All untreated hazardous elements remain in landfilled waste in much higher concentration than they occur naturally. To resolve this problem U, Th, and Tl were removed from phosphorite ore at first using liquid extraction. In the next step, REE were isolated from raffinate. Nitrated Aliquat 336 (A336[NO3]) and Bis(2-ethylhexyl) Phosphate (D2EHPA) were used in liquid extraction for comparison. An improved method for exclusive separation of radioactive elements and REEs from phosphorite ore in 2-steps has been developed, exploiting liquid extraction at different pH values.

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Syntheses and evaluation of new hydrophilic azacryptands used as masking agents of technetium in solvent extraction processes

Dalton Transactions ◽

10.1039/d0dt04210b ◽

2021 ◽

Vol 50 (5) ◽

pp. 1620-1630

Author(s):

Alexiane Thevenet ◽

Ana Miljkovic ◽

Sonia La Cognata ◽

Cécile Marie ◽

Christelle Tamain ◽

...

Keyword(s):

Nitric Acid ◽

Solvent Extraction ◽

Acid Medium ◽

Separation Process ◽

Nitric Acid Medium ◽

Masking Agents ◽

Extraction Processes

New azacryptands with the addition of hydrophilic groups were synthesized to bind selectively the pertechnetate anion in nitric acid medium, and avoid its extraction in the separation process.

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