Silver is a precious metal. A precious metal is a rare and naturally occurring metallic chemical element of high economic value. The best-known precious metals are the coinage metals, gold and silver. These precious metals are often seen as hedges against inflation and economic downturn.
RCRA 8 Metal
The Resource and Conservation Act (RCRA) monitors a group of eight heavy metals; arsenic, barium, cadmium, chromium, lead, mercury, selenium, and silver. These metals are extremely toxic at even small concentrations. The amount of each metal present in waste is highly regulated. The Environmental Protection Agency (EPA) allows only a certain concentration of each metal in waste. Click here to learn more about this group of metals.
Silver displays one of the four hazardous waste characteristics, toxicity. High concentrations of silver are toxic to aquatic life and people by way of inhalation and ingestion. When the source’s silver concentration is greater than 5.00 ppm (mg/L), the source must be handled as a hazardous waste.
The Resource Conservation and Recovery Act prohibit the land disposal of any hazardous waste unless it has been treated to minimize threats to human health and the environment. Due to the environmental hazards and economic value of silver, materials having high levels of silver concentrations must undergo precious metals reclamation or in general terms, silver recovery. Silver recovery is the process by which materials are refined for their traces of silver.
The spent photographic chemicals used to develop industrial x-ray film are known to contain high levels of silver and therefore must be managed according to the regulations set forth by 40 CFR Part 268 – Land Disposal Restrictions.
Silver is commonly used to make mirrors, electrical equipment, medical and dental equipment, and jewelry. The leading use of silver is in photography. Silver plays an important role in film. Photographic film is coated with a thin layer of silver chloride, silver bromide, or silver iodide. When exposed to light or radiation, the silver ions react and transform the film into an image. This not only applies to generic photography, but to conventional medical and industrial x-ray as well.
The spent materials used to develop film and the film itself, must be refined for silver recovery and recycled prior to disposal.