Silver Extraction from Jarositic Waste: Effect of Sodium Silicate on Cyanidation and Alkaline Decomposition as a Path to Revalorization
摘要
The solid residue generated during the purification stage of the hydrometallurgical process for high-purity zinc production, known as jarosite [KFe3(SO4)2(OH)6], is of economic interest due to its elemental composition. This study investigated silver extraction from jarositic waste sourced from an industrial facility in northern Mexico, using a conditioning process with sodium silicate, followed by cyanidation. The role of sodium silicate in facilitating alkaline decomposition of jarositic waste for silver recovery was also examined. The results showed that the highest silver extraction (55.3%) was achieved at a sodium silicate concentration of 200 g/t and a conditioning time of 60 min. Furthermore, CaO consumption decreased from 23.4 to 15.4 kg/t under these conditions. Additionally, the addition of 200 g/t of sodium silicate improved the decomposition process by promoting the dispersion of waste particles, enhancing their surface contact with the reaction medium. The findings indicate that conditioning jarositic waste with sodium silicate before cyanidation enhances silver extraction while reducing reagent consumption. This approach is particularly relevant considering that approximately nine million tonnes of jarositic waste are stored in tailings dams across Mexico, highlighting the potential for its effective revalorization.
Graphical Abstract