Lead nitrate-assisted cyanidation of silver telluride: accelerated silver leaching and partial tellurium dissolution

The addition of lead nitrate to the cyanidation of precious metal ores to enhance gold and silver dissolution is a common practice. This is especially true when dealing with refractory ores, such as gold and silver tellurides. An investigation was conducted to evaluate the dissolution behavior of silver and tellurium from silver telluride using lead nitrate-assisted cyanidation, with the aim of elucidating both the extraction efficiency and the underlying chemical pathway of the process. For this purpose, both batch standard cyanidation tests and cyanidation tests with lead concentrations of 50, 100, and 150 mg/L were carried out. During the experiments, dissolved oxygen and oxidation-reduction potentials were monitored. The solid residues of the experiments were characterized by X-ray diffraction and SEM-EDS to identify the tellurium/lead-related species produced by the reactions. The dissolution behavior of lead nitrate was also evaluated in the presence and absence of cyanide. The addition of 100 mg/L Pb(NO 3 ) 2 elevated Ag recovery from 6.4 % (no Pb) to 100 % in just 6 h, while Te dissolution rose from 6.9 % to 20.2 % after 8 h. XRD and SEM-EDS of the leach residues confirmed complete transfer of Ag into the [Ag(CN) 2 ] - complex, the precipitation of elemental tellurium, and the formation of PbCO 3 and Pb 2 OCO 3 ·(H 2 O) 2 , with no detectable Pb-Te phases. • Lead nitrate accelerates Ag 2 Te cyanidation, achieving 100% Ag recovery in 6–8 h. • Pb(II) addition shifts reaction pathway, enhancing oxygen utilization and redox kinetics. • Tellurium dissolution rises modestly (∼20%), with Te 0 precipitation dominating solid residues. • XRD/SEM-EDS confirm Ag transfer to [Ag(CN) 2 ] - and Pb redeposition as carbonate phases. • Coupling reaction kinetics with speciation enables sustainable Ag–Te resource recovery.