Separation of cobalt and lithium from mixed sulphate solution using Na-Cyanex 272

Basudev Swain, Jinki Jeong, Jaechun Lee, Gae-Ho Lee
  • Hydrometallurgy, November 2006, Elsevier
  • DOI: 10.1016/j.hydromet.2006.03.061

What is it about?

The paper embodies the solvent extraction behavior of cobalt and lithium from mixed sulphate solution using Na-Cyanex 272 as an extractant. The effect of different parameters such as pH of feed solution, extractant concentration, cobalt and lithium ion concentrations in the feed solution and stripping behavior using different mineral acids such as H2SO4, HCl , HNO3 have been studied. The highest separation factor of 62.00 was obtained with 0.03 M Na-Cyanex 272 at an equilibrium pH of 6.90 from mixed solution of 0.01M cobalt and lithium sulphate. About 84 % of cobalt was extracted with a minimum of 8 % lithium co-extraction at this condition. Cobalt was extracted as [CoA2·3HA]org with 65% Na-Cyanex 272. Two moles of Na-Cyanex 272 are required for the extraction of one mole of cobalt. A complete stripping of cobalt can be achieved from the loaded organic with 0.01M sulfuric acid solution. Cobalt sulphate solution with >99 % purity can be obtained.

Why is it important?

The paper embodies the solvent extraction behavior of cobalt and lithium from mixed sulphate solution using Na-Cyanex 272 as an extractant. The effect of different parameters such as pH of feed solution, extractant concentration, cobalt and lithium ion concentrations in the feed solution and stripping behavior using different mineral acids such as H2SO4, HCl , HNO3 have been studied. The highest separation factor of 62.00 was obtained with 0.03 M Na-Cyanex 272 at an equilibrium pH of 6.90 from mixed solution of 0.01M cobalt and lithium sulphate. About 84 % of cobalt was extracted with a minimum of 8 % lithium co-extraction at this condition. Cobalt was extracted as [CoA2·3HA]org with 65% Na-Cyanex 272. Two moles of Na-Cyanex 272 are required for the extraction of one mole of cobalt. A complete stripping of cobalt can be achieved from the loaded organic with 0.01M sulfuric acid solution. Cobalt sulphate solution with >99 % purity can be obtained.

Perspectives

Dr Basudev Swain (Author)
Institute for Advanced Engineering (IAE)

After optimizing the process the following conclusions can be made. (1) The highest 84 % of cobalt was extracted with a minimum of 8 % lithium co-extraction at an equilibrium pH of 6.90 which corresponds to initial pH of 5.00, 0.01M cobalt and lithium sulphate solution each in the aqueous feed solution and 0.03M Na-Cyanex 272 in the organic solution. At this equilibrium pH also the highest separation factor 62.00 was obtained. (2) Cobalt can be extracted as [CoA2·3HA]org species into the organic phase from mixed sulfate solution of cobalt and lithium with 65% neutral Na-Cyanex 272. About two moles of extractant Cyanex 272 are required for one mole of cobalt extraction at an initial pH of 5.00. (3) For the quantitative stripping of cobalt from loaded organic phase two moles of H+ (mineral acid) are required for one mole of cobalt. (4) When stochiometrically higher concentration of extractant employed for extraction, just after completion cobalt extraction, the lithium extraction starts which leads to lower efficiency of separation factor and higher contamination lithium along with cobalt. (5) Cobalt sulphate with about > 99.00 % purity can be prepared from mixed cobalt and lithium sulphate solutions using Na-Cyanex 272 as extractants by managing the suitable stochiometry. (6) The McCabe-Thiele extraction isotherm plotting for the extraction of cobalt reveals that two stages are required for quantitative extraction of cobalt and one stage is required for the quantitative stripping of cobalt.

The following have contributed to this page: Dr Basudev Swain