Relationship between Chemical Structure and Adsorption Preference to Metal Ions of Chelating Resins and Their Applications in Removal of Iron from Copper Leach Solutions

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The removal of iron is a necessary process with common concern in the production of pure nonferrous metals. Copper leach liquors must be purified to remove iron before copper recovery by electrowinning. We recently found that a hydroxy-oxime resin with excellent elution property, named Z-Fe, has selective adsorption for Fe over Cu. The research results have been published in Hydrometallurgy (Zhang et al., 2016), and presented to the International Mineral Processing Congress 2016. *** However, the functioning mechanism of this hydroxy-oxime resin Z-Fe is not clear. Literature review indicates that the relationship between the chemical structure of chelating resins and their adsorption preference to metal ions, which is critical for the selection and design of suitable resins for metal ion adsorption in hydrometallurgy, has not been fully understood and systematically studied. Understanding this relationship is the focus of this Discovery Grant proposal.*** Chelating resins have functional groups and can be of high adsorption preference to specific metal ions. They have broad prospective applications in recovery (or removal) and separation of metals from aqueous solutions. Through study on the relationship between the chemical structures of chelating resins and their adsorption performances for metal ions, which is a fundamental and long term systematic work, we will develop rules for the selection or design of resins used in the separation or recovery of metal ions. This will make the selection and design of suitable resins for metal ion adsorption a scientific procedure, rather than the current screening test procedure.*** For short term objectives (i.e., this program), firstly, the relationship between the chemical structure of chelating resins and their adsorption preference to metal ions (i.e., iron or copper ions in this study) will be determined by correlating their adsorption performances to iron/copper ions with their electronic/chemical structures. The fundamental rules for the selection or design of resins with adsorption preference to iron or copper ions will be developed. Secondly, to make the iron removal processes using chelating resins viable for commercialization, recovery of iron and recycling of elution agents (such as oxalic acid) by electrodeposition will be investigated. Removal of iron from copper leach solution using chelating resins is an innovative process. With this preliminary work, selection or design of resins with ideal iron removal properties is feasible. *** Our research results from this program and follow-up studies will provide theoretical guidance and have broad applications for the separation of metal ions using chelating resins in hydrometallurgy. These results may also have applications in the recovery of metals from oceans and removing heavy metals from contaminated rivers and lakes to improve environmental health, which will build up future study tasks.