Recovery of silver from thiourea solution by ion flotation

A laboratory investigation was undertaken on the silver-thiourea system for the recovery of silver by ion flotation. An anionic surfactant, sodium dodecylbenzenesulfonate, reacted readily with the silver-thiourea complex cation to form a colloidal precipitate (sublate), and the sublate was then floated by tiny bubbles. The influences of several factors on the flotation efficiency were studied. The recovery rate reached 96% under optimum conditions. Pure metallic silver was easily obtained from the floated sublate by thermal decomposition at 900 degrees C. The proposed process is fast, simple, and economical, and it may be useful for both laboratory and industrial recovery of silver.