Production

Tellurium is not usually mined specifically, but is produced as a byproduct of copper processing. During the electrolytic refining of copper, tellurium and other associated elements accumulate in what are known as anode slimes at the bottom of the plant. 

These residues are then treated in several steps to separate the tellurium from other metals they contain. To do this, the anode slimes are heated and treated with acids or alkalis. The tellurium is extracted during this process and then further purified. Tellurium dioxide, among other compounds, can be produced as an intermediate product, from which metallic tellurium is ultimately obtained. 

For applications in photovoltaics, thermoelectrics, or electronics, the tellurium must be exceptionally pure. That is why additional processing steps are required. The high-purity metal can then be used to produce tellurium-containing compounds such as cadmium telluride for thin-film solar cells or bismuth telluride for thermoelectric components.