Here's an interesting idea from bob the plumber regarding the silver foils in old keyboards..
Cupellation Method
Silver ore and scrap silver have to go through a refining process in
order for the pure silver to be separated from the dross. Cupellation is
when it is heated to 1,200 degrees Celsius in a special furnace. First
though, the silver scrap or ore is placed in a solution of 30 percent to
35 percent nitric acid. It takes an 40 grams of nitric acid to
dissolve 28 grams of silver.
The solution produces a white powder, silver chloride. When sodium carbonate is mixed with the silver chloride and placed in a cupellation furnace, the heat causes a chemical reaction and makes table salt and silver. The process works without the addition of sodium carbonate as well but then the heat releases poisonous chlorine gas as it produces the pure silver.
The solution produces a white powder, silver chloride. When sodium carbonate is mixed with the silver chloride and placed in a cupellation furnace, the heat causes a chemical reaction and makes table salt and silver. The process works without the addition of sodium carbonate as well but then the heat releases poisonous chlorine gas as it produces the pure silver.
