Extraction of Zn, Mn and Co from Zn-Mn-Co-Cd-Ni containing solution using D2EHPA, CYANEX® 272 and CYANEX® 302

Effects of pH, D2EHPA, Cyanex® 302 and Cyanex® 272 on extractions of zinc, manganese and cobalt from a Zn-Mn-Co-Cd-Ni containing solution was comprehensively investigated at the room temperature. The addition of Cyanex® 302 indicated a left-shifting-effect on the extraction curve of zinc, a right-shifting-effect on the extraction curve of manganese and no effect on the extraction of cobalt. The addition of Cyanex® 272 shifted all three curves to the right. The most suitable extractant for separation of zinc from manganese was therefore 0.3–0.3 mixture of D2EHPA with Cyanex® 302 and for separation of manganese from cobalt was sole D2EHPA. The stoichiometric coefficient for the extraction reaction of zinc (whether using pure D2EHPA or a mixture made of D2EHPA with Cyanex® 272 or Cyanex® 302) was 3. It varied from 4 to 5 for manganese, when the quantity of Cyanex® 302 dissolved in D2EHPA increased from 0 to 100%. Utilizing the above results, a two stage leaching was devised to recover zinc, manganese and cobalt from a complex solution. At the first stage, a 0.6M D2EHPA extractant could recover zinc and a scrubbing reaction with organic:aqueous (O:A) ratio of 20:1 could wash-out cadmium from the raffinate. In the second stage, the leaching residue was treated with 0.6M D2EHPA for recovery of manganese. This stage was then followed by a one-stage scrubbing of cobalt with O:A ratio of 20:1.