Separation of valuable metals from low nickel matte to prepare NiCo2O4 materials: Optimization of oxidative leaching process and improvement of electrochemical properties of materials

Abstract

The economical and efficient utilization of intermediate low nickel matte has become an important goal of nickel smelting industry. In this work, an innovative process of oxidative leaching of valuable metal from low nickel matte to prepare NiCo2O4 materials was proposed based on the materials utilization of mineral. The addition method and speed of ammonium persulfate in the oxidative leaching process was investigated to improve the extraction of valuable metals. The key factors affecting the leaching of valuable metals and the optimum leaching condition were determined by orthogonal experiments, and the extraction of Ni, Cu, and Co was 92.3 %, 97.1 % and 96.6 %, respectively. The leaching mechanism was clarified and the advantages of the leaching process were compared and analyzed. The kinetics of oxidative leaching process was studied by timing sampling method, and the control model, activation energy and kinetic equation of Ni, Cu and Co leaching were determined by analyzing the data with unreactive shrinkage model. The effects of Ni:Co ratio and calcination temperature of precursor on the properties of NiCo2O4 were investigated using the leaching solution removing iron and copper as raw materials. The NiCo2O4 material with the Ni:Co ratio of 1:2 prepared by calcining precursor at 750 ℃ for 3 h has a specific capacitance of 864F/g when the current density is 1 A/g. The prepared NiCo2O4 materials show good capacitance performance and has potential to be used as capacitor electrodes. This work combines metal extraction with product materialization, which is expected to help the metallurgical industry effectively shorten the industrial production process and reduce production costs.