Abstract
According to European regulations, indium and germanium are critical metals. Therefore, their recovery is a crucial issue. The present study was focused on the pyrometallurgical treatment of polymetallic PbSnIn and PbSnCuGeIn generated at the Miasteczko Zinc Smelter in order to recover In and Ge. The paper presents the production process of these alloys, as well as their characteristics. The materials were subjected to thermal processing in a laboratory-scale refining kettle fired with natural gas and air. Two different methods for the processing of the individual alloys are described. Two series (one for each material) consisting of five tests were performed in order to determine the optimal metal recovery parameters. The described pyrometallurgical process resulted in the production of an indium-enriched semi-product (In—1.15%) and a Ge–In-enriched product (Ge—11.1%, In—3.0%). Direct indium recovery rates were approximately 83% and >99%, respectively.
Highlights
On the basis of the List of Critical Raw Materials for the EU [1], germanium and indium are critical materials, which need to be processed and recovered efficiently in order to fulfill the requirements of the circular economy
It was observed that germanium was efficiently removed from the PbSnIn alloy with NaOH at the first step of the refining process
The obtained Zn drosses can be redirected to the ISP (Imperial Smelting Process), where the basic metals (Zn, Pb) will be recovered, while In and Ge will be concentrated during the zinc-refining process from PbSnIn and PbSnCuGeIn alloys
Summary
On the basis of the List of Critical Raw Materials for the EU [1], germanium and indium are critical materials, which need to be processed and recovered efficiently in order to fulfill the requirements of the circular economy. Germanium does not exist in its elemental form in nature, but it can be found in a relatively small number of mineral ores. It is present in certain types of coal, and is concentrated in the fly ash from coal-fired power stations. Such coals are found in parts of Russia and China [2]. Ge concentrations in processed materials are usually not high.
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