| A series of test work for Zn2+?Cd2+ solvent extraction by P204-kerosene from self-prepaired Zn2+ and Cd2+ bearing solutions and the acidic leaching solutions of Cu-Cd residue has been completed.The whole work is constituted by the following three parts. The first part is for the solvent extraction of Zn2+?Cd2+ from low concentration feed solution, in which aiming at understanding the basic solvent extraction characteristics of Zn2+?Cd2+ by P204. The secong part is investigating the solvent extraction behavior of Zn2+?Cd2+ from high concentration feed solution, which the Zn2+?Cd2+ concentration is similar to the acidic leaching solution of Cu-Cd residue. This work can be refered by the following Zn2+?Cd2+ solvent extraction tests from acidic leaching solution of Cu-Cd residue. In the third part, the solvent extraction of Zn2+?Cd2+ from acidic leaching solution of Cu-Cd residue was accomplished, in which the solvent extraction recovery of Zn2+?Cd2+ is examined.Test work for low concentration solution showed that the solvent extraction balance constant of Zn2+ by P204 changed from 0.17 to 1.2, similar to that by the same kind of abroad extractant, such as 0.4587 by DEHPA. The solvent extraction balance constant of Zn2+ by P204 changed from 1.07×10-3 to 6.9×10-3, also similar to 5.248×10-3 by DEHPA. Test results also showed that the introduction of additive A is helpful to increase the solvent extraction rate of Zn2+ and Cd2+, especial for Zn2+.When we extract Zn2+by 30%P204-kerosene from high concentration feed solution, such as 20 g/L and 50g/L Zn2+ feed solution, the recovery of Zn2+ increases with the increase of additive A addition, and the Zn2+ recovery reach 80.1% and 80.0%, respectively when additive A addition reaches stoichiometric coefficient of Zn2+. When additive A addition is more than stoichiometric coefficient of Zn2+, the Zn2+recovery will dropped. But this kind of drop has not been observed for the solvent extraction from 95g/L Zn2+ feed solution. And the Zn2+ recovery reaches 82.3% when additive A addition is 1.1 times the stoichiometric coefficient of Zn2+.When extracting Zn2+ by 30%P204-kerosene from 50 g/L and 5g/L Cd2+ feed solution with phase ratio at 3.0, the recovery of Zn2+ and Cd2+ reach 94.2% and 18.4%, respectively, in which additive A addition is at the stoichiometric coefficient of Zn2+and Cd2+. But the recovery of Zn2+ and Cd2+ only reach 39.0% and 16.0%, respectively, if without additive A addition. In a two stage series solvent extraction test with phase ratio at 1.8 and additive A addition at stoichiometric coefficient of Zn2+ and Cd2+, the recovery of Zn2+ and Cd2+ reach 98.7% and 26.0%, respectively. When phase ratio increases to 2.2, the recovery of Zn2+ and Cd2+ increases to 99.6% and 34.0%, respectively, and Zn2+ concentration in raffinate decreases to 0.38g/L.For the extraction of Zn2+ and Cd2+ by 30%P204-kerosene from sulfuric acidic leaching solution of Cu-Cd residue, in which [Zn2+]=43.13g/L, [Cd2+]=12.75g/L, When phase ratio increases from 1.5 to 4.5, the recovery of Zn2+increases from 13.3% to 24.2%, and the recovery of Cd2+ increases only from 2.0% to 3.9%. When extracting Zn2+ and Cd2+ with 30%P204-kerosene from additive A leaching solution of Cu-Cd residue, in which [Zn2+]=31.45g/L, [Cd2+]=7.50g/L, When phase ratio increases from 1.2 to 3.6, the recovery of Zn2+increases from 55.8% to 71.1%, and the recovery of Cd2+ increases only from3.3% to 6.7%.In a two stage series solvent extraction test of Zn2+ and Cd2+ from the additive A leaching solution of Cu-Cd residue, in which [Zn2+]=31.45g/L, [Cd2+]=7.50g/L, with phase ratio at 3.6. the recovery of Zn2+ and Cd2+ reach 85.4% and 13.7%, respectively. The loaded organic phase with [Zn2+]=6.80g/L, [Cd2+]=0.17g/L,when stripping this loaded organic phase with different concentration of sulfuric acid at 1:1 phase ratio, the stripping recovery of Zn2+ reaches 100% when sulfuric acid concentration is at 60g/L and 90g/L. But the stripping recovery of Cd2+ waves between 37.6% to 54.1%. |
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