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Abstract
A study was conducted to control iron in copper electrolyte streams using Eichrom Industries' new monophosphonic/sulphonic acid resin. The resin strongly and selectively extracts ferric ion over copper and cobalt from highly acidic copper electrolytes. The resin has a loading capacity of 27-g/L iron and can be readily regenerated. In addition, the new resin can easily be synthesized using commercially available starting materials. This paper presents the experimental results for iron control in copper electrolyte streams using the new resin and discusses its potential applications to other hydrometallurgical streams.
Key words: Resins, Ion exhange, Iron removal, Copper electrolyte solution
Introduction
Iron is one of the most important elements that must be removed during hydrometallurgical processing of copper, zinc, nickel and cobalt. Eichrom Industries developed the Iron Control Process (Gula et al., 1996), which uses Diphonix resin to remove Fe(III) from copper electrolyte solutions. The Diphonix resin exhibits a strong affinity for Fe(III) over mono- and divalent metals, such as copper and cobalt, and can be regenerated for further use. The Diphonix resin functions very well in the iron-control application and has been tested on a commercial scale.
This paper describes an application of a new bifunctional monophosphonic acid ion exchange resin that was developed and characterized by Alexandratos and co-workers at the University of Tennessee and by Horwitz and co-workers at Argonne National Laboratory (Alexandratos et al., 1998). This new bifunctional resin is called monophosphonic/sulphonic acid resin. The new resin has superior properties, in some cases, to the phosphonic acid ion exchange resins now commercially available (e.g., Diphonix resin and Duolite(R) C-467 resin) and described in the open literature (e. g., mono-phosphonic acid ion exchange resin). Figure 1 shows the chemical structures of monophosphonic/sulphonic acid resin, mono-phosphonic acid resin, Diphonix resin and Duolite(R) C-467 resin.
In the new resin, the phosphonic and sulfonic groups are attached to the same benzene ring in either the ortho or meta positions, Fig. 1(a). Unlike conventional sulphonic acid functional group cation resins, which are widely used in the water treatment industry and other industrial processes, the new resin contains additional complexing ligands, phosphonic acid groups, that are selective for certain metal ions, notably Fe(III) in highly acidic solutions.
Compared to monophosphonic acid resin, Fig. 1(b), the...