Hobbies And Interests
Gold Coatings
Visible quantities of gold inside computers and other machines can be carefully scraped off. Gold that is difficult to reach, such as that on the edges of motherboards, can be easily freed by using CBX gold stripping powder. The CBX powder dissolves the material to which the gold is attached. CBX should not be applied to the delicate interiors of machines because of the danger of destroying essential components. Gold here is best treated with an electrolyte, called StripFree. StripFree removes thin coatings of gold from computer chips, and other similar items, by drawing the gold away from underlying metals. StripFree will work with any of the following metals: stainless steel and steel substrates, nickel, and rhodium. Place the part in a solution of StripFree and charge it with three to six volts of electric current. The process is the reverse of electroplating. The electric current causes the gold to dislodge itself from the metal, and dissolve into the StripFree solution.
Gold That is Difficult to Reach
Sometimes the gold is extremely difficult to reach, or is available in only minute quantities on a given piece. For recovery of this gold, try aqua regia. Aqua regia is a combination of hydrochloric acid and nitric acid. Used since medieval times, it is the only acid capable of dissolving gold. Aqua regia is extremely corrosive and dangerous. It must be used in a well-ventilated area. 3 to 4.5 milliliters of aqua regia is required to remove the gold from every 1 gram of scrap. Aqua regia will react extremely violently with any non-gold items that are present in the scrap. For this reason, the acid must be added very slowly. The complete reaction may take several minutes. Larger pieces of scrap may actually appear undisturbed, but can instantly be broken up with a stirring rod. The reaction is complete when all bubbling has stopped, and the acid is cooled to room temperature. The cooled mixture is passed through a Buchner filtering funnel. The gold is precipitated from the mixture using ferrous sulfate, also known as copperas. The mixture is again poured through the Buchner filter. The gold can be washed with water, and treated with hydrochloric acid, to remove further impurities.