spaceships said:
Goran I refer you to my post above yours mate.
Jon
I saw that and have no more comments than we all prefer different styles of refining.
If you prefer to drop your CPU:s in AR and extract the gold from a solution heavy in base metals, it's ok and it works. Some of our members are doing that and it works for them.
If you prefer to remove as much of the base metals first with either nitric or hydrochloric acid it's okay. It adds a step and takes longer time, but the final drop is from a solution not as heavily in base metals and that could be important for some of our members.
As most scrap we refine has been used the surface of the plating is probably damaged so the acid can get to it even when fully plated. When it starts to dissolve the foils easily breaks. Some pins might survive but a lot base metal will be removed.
This process should work and I'm certain that some of our members are using it just fine.
My favorite is what I call modified AR, add AR to the CPU:s but don't use enough to finish the job. Then in the end the gold will cement out on the base metals and you can pour off the barren liquid with most of the base metals. Add more AR (and possibly also more CPU:s) while removing any ceramics where all the metals are gone from, it just takes up space. In the end you have a quite concentrated gold solution with less base metals.
This method takes a bit of experience and longer in time but suits me well. It's not a process I would recommend to a newbie.
This process is used by some of our members and it works great for them.
I would like to add a disclaimer to this. I'm not that experienced in refining CPU:s but I'm gearing up for the 80 kilo CPU lot I bought this summer. All I've made so far is started a 1 kilo test run of black MMX fiber CPU:s to assay how much gold there is in them. For these I decided to boil them in HCl to remove the legs, then I'm going to incinerate to get to the bond wires.
We all have different styles that suits our self, so chill out, there is more than one way to refine gold.
Göran