Extraction of zinc(II) from chloride media with a mixture of ACORGA (R) ZNX 50 and LIX (R) 54

The extraction of zinc(II) from acidic chloride media with a mixture of ACO RGA(R) ZNX 50 (a bibenzimidazole-based extractant denoted hereafter B) and LIX(R) 54 (a beta-diketone denoted hereafter HL) was investigated. A releva nt feature of this system is that zinc(II) is extracted from aqueous acidic solutions merely as a chlorocomplex with ACORGA(R) ZNX 50, namely Zn2Cl4B2 [i.e., LIX(R) 54 does not contribute to zinc extraction], but that the lat ter complex is destroyed with concomitant formation of ZnL2 in the bulk of the organic phase [i.e., a complex formed with LIX(R) 54] and transfer of c hloride ions into the aqueous phase when the organic phase is scrubbed with an aqueous solution of ammonia. Finally, zinc(II) can be stripped from the scrubbed organic phase with sulphuric acid, which gives an classical acidi c zinc sulphate solution. The interest of such a procedure is that the seri es of extraction, scrubbing and stripping steps allows not only the purific ation and concentration of zinc(II), but chiefly its transfer from a chlori de media from which its electrowinning is problematic (formation of granule s instead of sheets at the cathode) into a sulphate media from which the el ectrowinning is perfectly controlled.