Research On The Thermodynamic Properties Of Nickel- Cobalt Ore Bio-leaching Liquid

Researches about the iron removal process and the extraction & separation process of valuable metals for nickel-cobalt ore bio-leaching had already been continuously conducted, while studies about its thermodynamic properties has not been carries out. This paper firstly conducted research about chemical properties of nickel-cobalt ore bio-leaching, and obtained its thermodynamic properties and variation including viscosity, conductivity, activity coefficient, relative partial molar free energy, partial molar free enthalpy, and standard molar entropy.Under experimental conditions, results showed that leaching bacteria, as a composition of the bioleaching solution, had no obvious effect over its viscosity, while change of iron elements was an important cause for viscosity variation. Leaching bacteria’s effect on the viscosity was realized by changing the component structure of the solution. Studies found that its effects on the conductivity were consistent with that on viscosity. Characteristics of the viscosity were also studies in the paper.Iron is a major component of the leaching, and its thermodynamic state under a certain leaching bacteria concentration was analyzed by the Fe2+-Fe3+-Eh diagram. Results showed that the leaching bacteria obviously accelerated thermodynamic change of iron in the solution.To reflect the solution components’effect on its thermodynamic state, this paper used the Meissner-Pitzer Model to analyze the variation rule of the activity coefficient, and quantified change of thermodynamic properties of the system when the pH value and ion concentration changed. Prediction of the Model was consistent with the actual experimental results.This paper also used conductometric method to menstruate the average activity coefficient variation of the solution. Results indicated that when the concentration was certain, the average activity coefficient decreased with the rising temperature. And when the temperature was certain, it decreased with the rising electrolytes concentration. Based on the average activity coefficient, the relative partial molar thermodynamic properties under different temperature were obtained through the thermodynamic relation. Results showed that with the rising concentration in the system, the partial molar enthalpies and the partial molar free energy increased, while the partial molar entropy decreased. This paper also expressed the difference between situations with and without fungi.