Funded by Audi Environmental Foundation, a team of TU Bergakademie Freiberg is researching the recovery of strategically important raw materials. Indium, gallium or tin are not rare, but indispensable for modern technologies, such as semiconductor components or photovoltaic systems. The extraction of these metals is sometimes complex and therefore cost-intensive.
Despite the increasing demand for raw materials, these important elements are often unintentionally lost for usage. Small electrical appliances such as USB sticks, charging cables, flashlights and mobile phones are often carelessly disposed of in household waste and not at recycling collection points. Thus, the electrical components are mixed together with other waste and then incinerated in waste recycling, whereby the valuable elements end up as tiny particles in the resulting fly ash.
This is where the greenovation of selective extraction comes into play: an established chemical process that is being further developed in cooperation with the TU Bergakademie Freiberg and thus enables the recovery of indium, gallium and tin from the ash of waste incineration plants. By adding acid, all metal ions contained in the ash are first brought into solution. With the help of specially designed and self-produced molecules, so-called ligands, the dissolved metal ions in the solution are detected and precisely selected from the mass and separated from the mixture. In the last step, the ligands are dissolved from the metals by adding a fresh acid, resulting in a pure metal ion solution. This can then be further processed and, as a recovered metal, integrated into the value cycle in an environmentally friendly manner and used for producing new electrical appliances.
The selective extraction process is currently being further optimized in order to establish it as a pioneering technology for environmentally friendly recycling of industrial metals from existing resources both in Germany and internationally in the coming years.