The Oxidation of Fe(II) in Acidic Sulfate Solutions with Air at Elevated Pressures. Part 1. Kinetics above 1 M H₂SO₄

Abstract

The oxidation of ferrous ions in acidic sulfate solutions at elevated air pressures was investigated. The effect of the Fe2+ concentration, initial H2SO4 concentration and partial oxygen pressure on the reaction rate were determined at three different temperatures, that is, T = 90, 70, and 50 °C. The effect on the reaction rate of the components that H2SO4 dissociates into, that is, HSO4 –, H3O+, and SO4 2–, was established as well. A second order of reaction in Fe2+ and a first order of reaction in O2 were determined. No clear order in either H2SO4 or the components H2SO4 dissociates into, could be established. For the experiments with initial concentrations of H2SO4 of 1 M and higher the oxidation rate was not affected, that is, a zero order of reaction in H2SO4 for these concentrations. Therefore, the kinetic rate expression for the oxidation of Fe2+ at concentrations of H2SO4 of 1 M and higher can be calculated with R Fe2+ = d­[Fe2+]/dt = k[Fe2+]2 P O2 , where the activation energy E A was determined to be 60.3 kJ/mol.

Dissolution of CuS Particles with Fe(III) in Acidic Sulfate Solutions

“…Copper sulfide (CuS), also known as covellite, and sulfuric acid are formed in the gas treating process: 2 The Vitrisol process is able to remove H 2 S from acidic gas streams without the coabsorption of CO 2 . 2,4 Because the precipitation reaction occurs very rapidly, the removal of H 2 S is limited by mass transfer in the gas phase.…”

“…Ferrous sulfate can be reoxidized to ferric sulfate with O 2 , according to Wermink and Versteeg 4,7 studied the oxidation of ferrous ions in acidic sulfate solutions (reaction 3), and proposed kinetic equations derived by fitting both the initial reaction rates and the experimentally determined Fe 2+ concentration profiles as a function of time, respectively.…”

The Oxidation of Fe(II) in Acidic Sulfate Solutions with Air at Elevated Pressures. Part 2. Influence of H2SO4 and Fe(III)

“…Copper sulfide (CuS) and sulfuric acid are formed in the gas treating process, without coabsorption of CO 2 : , The Vitrisol liquid can be regenerated through oxidation of CuS by ferric sulfate (Fe 2 (SO 4 ) 3 ). Copper sulfate, elemental sulfur (S o ), and ferrous sulfate (FeSO 4 ) are produced in the process: Ferrous sulfate can be reoxidized to ferric sulfate with O 2 , according to Resulting in the overall net reaction for the removal of H 2 S: In Part 1 Wermink and Versteeg investigated the oxidation of ferrous ions in acidic sulfate solutions (reaction ), and proposed a power law kinetic equation for the oxidation of Fe 2+ at concentrations of H 2 SO 4 of 1 M and higher. The kinetic equation was derived by fitting initial reaction rates.…”

“…In Part 1 Wermink and Versteeg concluded that interpreting the results in terms of activities or chemical potentials could possibly clarify the influence of H 2 SO 4 on the reaction rate and mechanism, respectively, because the effect of H 2 SO 4 on the oxidation reaction might be attributed to SO 4 2– ions. The kinetic equations derived in Part 1 4 and this study are used for the design of the Vitrisol process.…”

“…For an extended literature review on the oxidation reaction of ferrous ions in acidic sulfate solutions the reader is referred to Wermink and Versteeg …”