Study On The Oxidation-precipitation Of Cobalt(Ⅱ) In Solution By Ozone And Its Application In Metallurgy

Abstract:In the cobalt metallurgy, there are some technologies or processes used for the separation and enrichment of cobalt, such as oxidation-precipitation method. Oxidization-precipitation method has advantages of easy operation and short flow. The ozone was used as oxidant in the study for oxidiation-precipitation of cobalt which was clean without any pollution in the study. The mechanism of oxidation-precipitation process of cobalt by ozone and the application of the technology in the metallurgy were systematic studied in the paper.The results were showed below:(1)The oxidation-precipitation of cobalt by ozone in the solution of cobalt sulfate was studied. The CoOOH was produced in the study. The molar heat capacity(Cp) and the Gibbs free energy(ΔfG(?)m=-382.099kJ·mol-1) of CoOOH were obtained by thermodynamics study, at the same time the solubility-equilibrium diagram was drawn.Cp(CoOOH)=-140.8xT-1.055×109×T-2+0.1332×T2+4.237x104(J/mol·K)(2)The kinetic study of oxidation-precipitation of cobalt was studied. It was known that the apparent activation of reaction was383J·mol-1,which means the control-step of the reaction was diffusion where the reaction rate was influenced by diffusion process.The reaction was influenced by many factors, such as O3concentration, gas flow, stirring speed and pH value, where the factors have direct effect on the rate of cobalt removal; While the temperature and cobalt concentration had little influence on the reaction. The kinetics equation of reaction was established where the oxidation effect by ozone was consist of direct-oxidation and indirect-oxidation.(3)The study of cobalt recovery from leaching solution of cobalt-rich slag was carried out. Copper and zinc lost in the precipitation in the form of adsorption and inclusion. From the studies above, It was seen that the technology of oxidation by ozone could be used for separation of cobalt from simply multi-metal solution. (4)In the study on the treatment of leaching solution of cobalt-slag by two-stage process, the manganese and cobalt were separated and enriched effectively. When the pH value was greater than3.5, the concentration of cobalt could be less than20mg/L, and when the concentration of zinc was57.65g/L with pH value less than3.5,the cobalt precipitation which cobalt content was about38%was obtained; The zinc was lost in the precipitation in the form of basic zinc sulfate.