An Efficient Hydrometallurgical Process for Extracting Tellurium From Copper Telluride Slag

Copper telluride slag from copper smelting process is an important source of tellurium (Te). In this work, an efficient and economical hydrometallurgical process for extracting Te from copper telluride slag was proposed. First, H₂SO₄ and NaClO₃ were demonstrated to be effective for separating Te and Cu, and the leaching efficiency of Cu(II) reached 99.44 pct, while that of Te(IV) was only 3.00 pct. Tellurium oxide in the oxidative acid leaching residue was dissolved in NaOH solution, and Na₂S was added as precipitant to purify alkali leaching solution. Valuable metals (Bi, Se, Pb, Sb, Ag, Au) were enriched in alkaline leaching residue. Furthermore, the separation of Te and Se was realized by adding H₂O₂ in alkali leaching solution, the precipitation efficiency of Te(VI) was up to 99.43 pct. Finally, Te(VI) was reduced by Na₂S-Na₂SO₃, and the reduction efficiency was 99.85 pct under optimized conditions. The results show that 96.18 pct of Te can be extracted as elemental Te powder with a purity of 99.98 pct, indicating that the process achieves an efficient extraction efficiency of Te from copper telluride slag.