Selective extraction and recovery of copper from chloride solution using Cextrant 230

The extraction behavior of Cu(II) from chloride solution was investigated using di(2-ethylhexyl) [N-(2-ethylhexyl)aminomethyl] phosphonate (Cextrant 230, L). Cextrant 230 has a higher selectivity for Cu(II) over other divalent metal ions, e.g. Co(II), Ni(II), Mg(II) and Ca(II). The effect of the concentration of chloride ion and the extractant, aqueous pH values and temperature on the Cu(II) extraction was studied in detail. A possible extraction mechanism was proposed and the extracted complex was determined to be CuCl2·3L by the slope analysis method. Thermodynamic parameters (ΔG, ΔH and ΔS) were calculated, suggesting that the copper extraction was an exothermic process. The loading capacity of 30% (v/v) Cextrant 230 was 16.9 g Cu/L. The loaded Cu(II) can be stripped efficiently by HCl, HNO3 and H2SO4. A extraction process for the selective extraction and recovery of Cu(II) from a raffinate obtained after the recovery of rare earths from the waste NdFeB magnets was proposed, by which the purity of copper product reached 99.5% with a yield of 98.0%.