TELLURIUM SPECIATION AND RECOVERY DURING CU ORE PROCESSING

Essentially all tellurium (Te), an element used in solar panels and other high technology devices, is recovered as a byproduct of copper mining. Recent increases in demand have sparked questions of long-term supplies of Te (crustal abundance ≤ 0.01 mg kg^-1). As part of a larger study investigating Te resources, we examined the deportment of Te during Cu smelting and refining as a first step toward optimizing Te recovery. Mass balance calculations estimate that only 27% of the Te in the concentrate remains in the Cu anodes produced by a domestic smelter, while 67% and 11% is lost in the slag and dust, respectively. X-ray fluorescence (XRF) mapping showed that Te has a strong correlation to Fe, S and Cu throughout the smelting and refining process. X-ray absorption spectroscopy (XAS) was used to examine Te and S speciation in anode slimes. Surprisingly, we found that tellurite (Te^IV), rather than telluride as has been previously reported, was the dominant form in our anode samples. Sulfur, also a group 16 element occurring at wt % concentrations, speciation was much more complex with a mixture of species. These results represent an important step in potentially optimizing Te recovery during Cu processing.