Recovering Silver From Computers
In my last article I described how to recover gold from computer components that are no longer of any use. In this article I will focus on recovering silver from these components.
I will start by stressing the need for safety when working with the chemicals involved in the processes for recovering precious metals from computer parts. Before purchasing and using these chemicals, you need to check your local and state laws regarding the use and disposal of the chemicals used.
You want to start with a computer that has been dismantled as described in the last article. The main focus is the silver that is used for solder and other fine parts of the circuit boards. These boards can be taken and placed into a glass container. The circuit boards may have to be broken or cut up to fit them into a container. This is totally acceptable and will allow you to fit more circuit boards in one container.
Once the materials have been placed into the container, you then want to add 70% nitric acid to the point where the acid just covers the top of the materials. The acid should be added slowly and all precautions should be taken including respiratory and splash precautions. As always, this should be done in a well vented area or under a fume hood.
Once you have added the acid, you will notice a reaction taking place. This reaction is the acid reacting with the metals contained on and in the materials. The acid will take about ten days to finish unless heated which then reduces the time to a couple hours. If you chose to use heat, do not boil! The amount of heat used should be about the equivalent of a coffee pot.
Once the reaction is complete you will notice that the acid has taken on a bluish green color. This coloring is due to the copper that has been dissolved by the acid. The acid should then be poured through a filter into another glass container leaving the solid pieces of material behind. You must use a filter such as a coffee or painters filter due to the fact that nitric acid will free up some of the gold on the material as well. Once you have poured off the solution you want to check the filter for gold. If you find gold in your filter you can add it back to the original container and set aside.
Now, with your container of acid separate, slowly add salt to the solution. You will notice that the acid will slowly turn white as the silver starts to drop out of the acid. Stir occasionally until the entire container shows the silver precipitating.
Let the acid set for a few hours or until all of the silver has fallen to the bottom of the container. Then pour off the remaining acid leaving the silver on the bottom of the container. The silver will have the appearance of grey cottage cheese. Fill the container with enough water so that you can pour the silver into a coffee or paint filter. Rinse the silver in the filter with water until the water that runs through is clear.
Set the clean silver aside and let it dry. Once it has dried completely, you can then melt the silver into its recognizable, solid metal state.
The remaining material in the original can then be refined as described in my previous article on recovering precious metals from computers.