Selective removal of radioactive 210Pb(II) and nonradioactive Pb(II) isotopes from Cu(II)-rich acidic chloride solution by a new polyamine anion exchanger

Abstract

In clean production of copper sulphide concentrate, both radioactive 210Pb and nonradioactive Pb isotopes are dissolved into HCl solution, while Cu from copper concentrate product is also leached into the same solution. Herein, a new polyamine anion resin –Lewatit A365– has been employed to selectively remove the trace amounts of Pb(II) from Cu(II)-rich acidic chloride solutions. Thermodynamic modelling for metal-chloride speciation and batch adsorption tests for both synthetic and real leach solutions suggest that the resin selectivity for Pb(II) over Cu(II) adsorption increases with the increase of Cu/Pb mass ratio (1–1000) in solution. The highest separation factor of Pb(II) over Cu(II) is 1920.6 from acidic chloride solution containing 50 mg/L Pb(II) and 50,000 mg/L Cu(II). The adsorption mechanisms of Pb(II), Cu(II) and Cu(I) chloride complexes on polyamine resin was elucidated by X-ray near edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) spectra. The results show that the resin exerts a strong stereochemical control on the adsorbed species, which have different coordination environments on the resin compared to the solution. This work sheds light on the Pb element removal from acidic chloride solution and on the cleaner production of copper sulphide concentrate, supporting the sustainable utilization of copper resources.