Kinetic study of ferrous sulfate and copper monosulfide oxidation in aqueous sulfate solution by molecular oxygen - Development of the Vitrisol process that is 100 % selective for H2S

Abstract

In this thesis were investigated two reactions which take place in oxidation stage of Vitrisol® process. The oxidation of ferrous ions in aqueous solution by molecular oxygen, kinetics of which have been already determined under various conditions of temperature in range of T=50÷90 oC;, partial pressures of oxygen ranging from pO_2=225÷1800 (mbar) and various initial concentrations of cFe(+2)=0.0625÷1 (M), cFe(+3)=0.0625÷0.5 (M), cCu(+2)=0.015625÷0.5 (M), c_H2SO4=0.27÷2.0 (M). Based on experimental results, a rate equation was developed, described by kinetic parameters which were estimated in accordance with Newton-Raphson method, based on curve fitting. Based on curve fitting, a comparison of the simulated values with experimental data revealed that the model describes the oxidation kinetics well in accordance with following kinetic parameters: - second order in ferrous ions - 0.9 order in partial pressure of oxygen - 0.25 order in cupric ions - 0.2 order in sulfuric acid - (-0.55) order in ferric ions The activation energy involved has been found to be equal to 66.06 (kJ/mol). The oxidation of copper monosulfide was investigated within three experiments performed at 90 oC; and 0.125 M initial concentration of cuprous ions. Conversion of cuprous ions into cupric ions was achieved in proportions of 80%, in a record time of 30±(5) minutes.