Selective precipitation of rare earth and critical elements from acid mine drainage - Part I: Kinetics and thermodynamics of staged precipitation process

Critical elements (CEs) have been in the spotlight recently due to their promising role in green energy transition and high-tech developments. Secondary resources, such as acid mine drainage (AMD) are of great potential source for these elements. Selective recovery of CEs such as Al, rare earth elements (REEs), Co, and Mn from AMD is deemed viable. To design and scale up the CEs recovery process, parameters such as kinetics and other thermodynamics parameters are vital. This work determined the reaction rates for precipitation of the Al, REEs, Co, and Mn in a three-staged precipitation process. The experimental data were examined with Avrami and second-order kinetics models. Analyzing the parameters driving and controlling the precipitation showed that the mechanism in the precipitation of elements from the solution is the supersaturation of species. Furthermore, the condensation and polymerization of the metal ions with ligand molecules results in large polycation complexation and growth.