Ligand selection for complex-leaching valuable metals in hydrometallurgy

A two-stage ligand selection method composed of a primary selection and a critical selection, for complex-leaching valuable metals was presented. At the primary selection stage, three conditions were discussed under a supposed ideal state by mathematical derivation. Generally, ligands selected under condition I, were easier for complex-leaching valuable metals than that under condition II, however, under condition III, ligands selected were hard to complex-leaching the valuable metals. Ligands that were out of these three conditions could be disposed directly. In critical selection, ligands selected in primary selection can be finalized. Case applications were provided for verifying the method. The application indicated that iminodiacetate (Ida2−) can be used as a complex agent for complex-leaching smithsonite (ZnCO3); the leaching condition should be controlled with pH 8–11; the relative error of the minimum consumption of Ida2− between the predicted and the calculated results is 5.3%. The results indicate that the theoretical derivations in the ideal state are reliable, and the method for ligand selection is practical and operable.