A recent project that I had in my workshop required me to remove gold (probably 22k) out of a set of silverware (sterling silver). To do that I tried a few methods and the winning one was a potassium cyanide gold stripping solution sold by a plating supplier. The project was successfuly done and now I am left with 7L of gold bearing solution that I would like to recover the gold from. I have been reading the C. M hoke book and learning the art of refining but I am new to that and I ran into a problem of not being able to precipitate the gold out of the KCN solution. More precisely, working with 1L of solution, I was able to precipitate some gold. I used 325 mesh zinc powder for the precipitating process but nothing happened so I added 3% hydrogen peroxide (outside with a fan blowing on it away from civilization and with a fume grade mask). When adding the hydrogen peroxide I had some precipitation and I thought that all the gold in there precipitated. Now after getting the end result of the refining process I only have about 3g of fine gold and that leads me to suspect that not all the gold was precipitated since the 1L of sulotion can hold up to 60g of gold. Any advice on how to correctly precipitate the gold out of the solution will be welcomed.
Some more technical details :
-ph of solution is about 12
-I used 325 mesh zinc then added zinc bar to stand over night.
-I experimented with small amounts of 10ml solution and observed precipitation by adding hydrogen peroxide to the solution without adding any other metal (my thought is that the KCN turned into HCN those leaving free gold molecules, but no chemist so I'm not sure)
-reading about it I realize that KCN can also desolve silver so I don't really expect to get 60g/L of gold but 3g seems way too low considering the thinness of the gold plating.
Some more technical details :
-ph of solution is about 12
-I used 325 mesh zinc then added zinc bar to stand over night.
-I experimented with small amounts of 10ml solution and observed precipitation by adding hydrogen peroxide to the solution without adding any other metal (my thought is that the KCN turned into HCN those leaving free gold molecules, but no chemist so I'm not sure)
-reading about it I realize that KCN can also desolve silver so I don't really expect to get 60g/L of gold but 3g seems way too low considering the thinness of the gold plating.