High technology’s dependence on critical elements, such as tellurium, has sparked uncertainty regarding future supply of Te and large-scale deployment of Te-containing solar technologies.  Less discussed are environmental and health implications of extraction, geographic redistribution and device disposal of such elements.  Tellurium (>0.1 mg kg-1 average crustal abundance) is enriched in Au-Ag telluride deposits, but exclusively extracted as a byproduct of copper mining.  Accurate quantification, maximization of Te resources, and responsible environmental practices relies on an improved understanding of Te geochemistry in the ore-forming environment, deportment during extraction processes, and behavior in surficial environments.  

We are examining Te speciation in ores, extraction processes, and in oxic weathering environments.  The distribution of Te between telluride mineral inclusions and substitution in sulfides has important implications for hypogene Te geochemistry and ore formation based exploration models and optimizing extraction efficiency.  In examining a variety of ores, we have electron microscopy, LA-ICP-MS, and u-XRF data suggesting that Te can substitute into sulfide minerals in some environments.  This information, coupled with Te mass balance calculations can help in designing extraction best practices.  We are working with modern Au and Cu mines in an effort to perform a mass balance of Te through their current extraction process.  The Cu mine recovers only 27% of the Te arriving at the smelter (with 61% and 12% being lost to slag and dust, respectively).  However, there are several waste products enriched in Te that might be further processed to improve extraction efficiency.  Historic mine tailings are also being examined as potential Te resources and to assess the associated health risks.  Initial assessments of the weathering trajectory of tellurides in the surficial environment indicate that in semi-arid environments, TeVI accumulates in the surficial layers of tailings, often in the presence of sulfides.  These ongoing studies represent an important first step in assessing the future of Te in high technology.

Data to present
Au-Ag
Emperor u-XRF: Te minerals and S substitution apparent
Golden Sunlight (401-402): high and low Au.  Te associated with different elements

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