Abstract
A precipitation stripping reaction of fine Sm2(C2O4)3·10H2O crystals from an organic solution containing the acidic extractant such as VA10 and D2EHPA by using an aqueous oxalic acid solution was investigated to provide the basis of a novel hydrometallurgical route for the recovery of metal values from scrap Sm-Co permanent magnets.
It was found that Sm2(C2O4)3·10H2O can be readily crystallized by stripping Sm(III)-loaded organics containing the acidic extractant by using an aqueous oxalic acid solution. The percent recovery of samarium oxalate from the organic phases containing VA10 or D2EHPA increases with the increase in oxalic acid concentration. Although the precipitation stripping reaction of samarium oxalate from Sm(III)-loaded VA10 takes place quantitatively, the excess amount of oxalic acid is required to recover samarium oxalate crystallines from Sm(III)-loaded D2EHPA. The concentration of Sm(III) and extractant in the organic phase and that of acid added to the stripping solution to adjust its pH value had little effect on the stripping reaction from Sm(III)-loaded VA10, whereas the percent recovery of samarium oxalate from D2EHPA extracted Sm(III) was considerably influenced by those factors. Although the size of needle-like crystallines recovered from the former organics is 1∼5 μm in length, that from the latter organics is slightly larger.
