Recovery of Tellurium from Cyanide Leaching Gold Tailings and the Leaching Mechanism of Lead Telluride

It is significantly challenging to extract Te from gold-leaching tailings. The effects and the leaching mechanism of direct alkaline leaching and oxidation-roasting alkaline leaching processes on tellurium recovery from cyanide-leaching gold tailings are studied in the Xiaoqinling region, Shaanxi, China. The results show that the leaching of tellurium from PbTe can be promoted with the pretreatment of oxidation roasting. XRD and TG analyses indicate that in the direct alkali leaching process, insoluble PbS film covers the surface of PbTe and hinders the reaction between the leaching agent and PbTe, resulting in a low Te leaching rate, but in the oxidation roasting process, PbTe is transformed into PbTeO3 and TeO2. The reaction between PbTeO3 and Na2S forms soluble Na2TeO3 while that of TeO2 with NaOH produces soluble Na2TeO3, thus promoting Te from PbTe. The tellurium leaching rate remains low because of the coverage of the PbSO4 and PbS on the surface of PbTe produced during the oxidative-roasting alkali leaching, which hinders the dissolution of PbTe. The process was consistent with the result of solid film diffusion. This research provides valuable theoretical guidance and practical significance for the development of integrated recovery technology of tellurium with associated elements.