Determination of Oxidation-Reduction Potential and Iron Chemistry for Solutions Generated During the Hydrometallurgical Extraction of Copper

Jiahao Xu, University of Texas at El Paso


Oxidation-reduction potential (ORP) based on iron chemistry is one of the key operating parameters during the hydrometallurgical extraction of copper. A novel ORP equation was developed previously only based on the variables of temperature and nominal ferric/ferrous ratio to predict the redox potential of the quaternary H2SO4-Fe2(SO4)3-FeSO4-H2O system. However, its applicability in more complex acidic iron sulfate solutions during the hydrometallurgical extraction of copper with different temperatures, acidic concentration, cupric concentration, nominal ferric/ferrous ratio, and total and l iron concentration has not been extended and validated. This work evaluates the applicability of novel oxidation-reduction potential equation in the H2SO4-Fe2(SO4)3-FeSO4-H2O and H2SO4-CuSO4-Fe2(SO4)3-FeSO4-H2O systems with various solution compositions in the temperature range of 5-60℃ typically employed in the industry, and also investigate the species distribution based on a developed thermodynamic model to better understand the iron chemistry.The broader range of applicability of this equation to other complicated acidic iron solutions containing cupric ions has been extended and validated. Synthetic iron-containing solutions with cupric ion based on the industrial processes of heap leaching (for pregnant leaching solution, PLS), solvent extraction (SX), traditional copper electrowinning (Cu EW), and novel copper electrowinning have been employed to measure the ORP at different temperature (5-60 ℃). This equation was validated by reliable and accurate prediction of measured redox potential and thus is highly useful to understand the iron chemistry of industrial leaching, solvent extraction, and copper electrowinning processes. According to the species distribution study, most Fe (III) is distributed as complexes and the free ferric ion accounts for only a minor percentage, with the existence of a large amount of Fe(II) in the form of a free ferrous ion. The change of redox potential with temperature for various nominal ferric/ferrous ratios could be explained well by the speciation model results for all the solutions mentioned above generated in industrial processes. The findings from this work contribute to the research on ORPs and speciation of acid iron sulfate solutions under various conditions and the understanding of iron chemistry of industrial processes for the hydrometallurgical extraction of copper.

Subject Area

Engineering|Materials science|Thermodynamics|Organic chemistry

Recommended Citation

Xu, Jiahao, "Determination of Oxidation-Reduction Potential and Iron Chemistry for Solutions Generated During the Hydrometallurgical Extraction of Copper" (2022). ETD Collection for University of Texas, El Paso. AAI30245805.