FeCl3 bearing etching solution is mainly used for etching of metals used in shadow masks, PCBs and so on. Due course of Invar alloy etching process the FeCl3 bearing etching solution get contaminated with Ni2+ which affect adversely the etching efficiency. Hence, FeCl3 bearing etching solution discarded after several cycle of operation causes an environmental and economic problem. To address both the issues the etching solution was purified through solvent extraction and remained Ni2+ recovered by wet chemical reduction using hydrazine. For optimum Fe3+ extraction efficiency, various extraction parameter were optimized and size and morphology of the recovered pure Ni powder was analyzed. The reported process is a simple process to purify and recover Ni from industry etching solution.

In this study, a rare earth composite precipitation (NaREE(SO ₄) ₂H ₂O, REE: Ce, La, Nd, Pr) powder was prepared from spent nickel hydride batteries, and cerium hydroxide was separated from its constituent rare earth elements. As Ce(OH) ₃ can be oxidized more easily than other rare earth elements (La, Nd, and Pr), Ce ³⁺ was converted to Ce ⁴⁺ by injecting air into the leachate at 80°C for 4 h. The oxidized powder was leached using sulfuric and hydrochloric acids. Because Ce(OH) ₄ has low solubility, it can be separated from other elements. Therefore, the pH of the leaching solution was adjusted for selective precipitation. To determine the crystalline phase, recovery, and grade of the recovered Ce(OH) ₄, the powders were analyzed using X-ray diffraction, scanning electron microscopy, and inductively coupled plasma optical emission spectroscopy. The grade and recovery rates of the Ce(OH) ₄ powder recovered from the rare earth composite precipitate using sulfuric acid as the solvent were 95% and 97%, respectively, whereas those of the powder recovered using hydrochloric acid were 96% and 95%, respectively.

As the amount of high-capacity secondary battery waste gradually increased, waste secondary batteries for industry (high-speed train & HEV) were recycled and materialization studies were carried out. The precipitation experiment was carried out with various conditions in the synthesis of LiNi0.6Co0.2Mn0.2O2 material using a Taylor reactor. The raw material used in this study was a leaching solution generated from waste nickel-based batteries. The nickel-cobalt-manganese (NCM) precursor was prepared by the Taylor reaction process. Material analysis indicated that spherical powder was formed, and the particle size of the precursor was decreased as the reaction speed was increased during the preparation of the NCM. The spherical NCM powder having a particle size of 10 µm was synthesized using reaction conditions, stirring speed of 1000 rpm for 24 hours. The NCM precursor prepared by the Taylor reaction was synthesized as a cathode material for the LIB, and then a coin-cell was manufactured to perform the capacity evaluation.