Cost effective selective separation of indium and germanium from zinc processing waste leach liquor using D2EHPA-YW100 synergistic system and selective stripping with HCl and NH4F

Indium and germanium are rare elements and contribute to supporting materials for contemporary high technology new materials. Research and development of efficient separation and extraction of indium and germanium have important practical significance. A new process of “one step extraction and stepwise stripping” is proposed in this work to coextract indium and germanium with D2EHPA-YW100 synergistic system of Di(2-ethylhexyl) phosphoric acid (D2EHPA) and C7–9 hydroxamic acid (YW100) denoted by D2EHPA-YW100. In the coextraction process, 98.9 % of indium and 99.9 % germanium were extracted utilizing an organic phase consisting of YW100 (1.4 %), D2EHPA (15 %) and sulfonated kerosene (83.6 %). During the two-step stripping process, 99.9 % of indium was selectively stripped from the loaded organic phase in step-1 using 4 M HCl. In step-2, 99.5 % of germanium was stripped using a 1 M NH₄F solution. This separation resulted the enrichment of germanium concentration by 6–7 fold and indium concentration by 19 fold. This method has four advantages: (i) simplifies the separation process, (ii) reduces equipment investment by nearly 50 %, (iii) minimizes extraction agent loss, and (iv) reduces management and labor costs.