Recovery and recycling of materials in industrial processes become more important, not only for pollution control but also economically. Reliable and unhindered access to certain raw materials is a growing concern within the EU and across the globe. Germanium (Ge) is listed as one of the critical raw materials (CRM) by the European Commission. In this work, we have investigated the recovery and repurification of Ge. Ge material processing for crystal growth involves several process steps, reduction of germanium dioxide (GeO₂) powder, zone refinement of reduced Ge metal bars, etc. During these multiple-processes, Ge is being lost at several steps. However, mainly, the loss is more in the sawing process of zone refined Ge bars.

Our recovery process of Ge metal starts with the oxidation of the sawdust via hydrogen peroxide with a concentration of 10% (2.97 mol/L). It is a quick and exothermic reaction. Hexagonal pseudo-cubic GeO₂ with a crystallite size of around 2 μm was obtained with a yield of 97%.  Besides forming the GeO₂, this first step also reduces the amount of impurities by about 0.4% achieving a purity of 98.4%. To decrease the impurities further, chlorination-distillation has been performed as a second step, reaching a purity of 99.998%. This chlorination-distillation is very time consuming, needs a special experimental setup in-which a yield of <50% was achieved. Hence, another method namely, acid leaching with HCl was chosen. The focus is set on the metals of interest such as Al, Cu and Fe. The amount of Al that could be reduced is 99%, Cu by 89% and Fe by 98% according to the ICP-OES measurements, achieving an all in all purity level of 99.98% with a total yield of 86%. The optimal conditions and more details will be discussed in this presentation.