Silver metallurgy

Silver is both a precious and an industrial metal (photography, electronics, soldering, etc.). Its main properties are its high electronic and thermal conductivities, and its reflectivity.

Silver mine production covers more than 2/3 of demand. Silver prices always follow those of gold and, like gold, undergo speculative phases.

In nature, silver is associated, often in elemental form, with gold, copper, lead and zinc. Silver sulfides and sulfosalts also exist. When silver is associated with gold, the metallurgical extraction method universally used is hydrometallurgy based on cyanide solubilization, followed by adsorption on activated carbon or cementation (precipitation) with zinc powder. When silver is associated with sulfides, it is recovered during the processing of sulfide concentrates (pyrometallurgy for lead concentrates, pyro-hydrometallurgy for copper concentrates, hydrometallurgy for zinc concentrates). The smelter applies bonuses for the silver content of these base metal concentrates, but the refiner only pays for 93-99% of the silver contained. Production costs can vary by a factor of three, depending on the operation and the country. The major producers are located in Australia, Canada, Chile, Mexico, Peru and the United States.

The recovery of silver from solid or liquid waste is always complex, and must be adapted to each sector of activity. The average recycling rate for silver is 20%.

The main sources of silver pollution are the photographic, mirror and electroplating industries.