I'm experimenting with a method to bring the acid costs down and recover the coper from refining process.
Please advise and comment if this is a good idea and or I'm missing something.
First of all I strip the boards from SMDs and connectors in plain HLC, after 2-3 days everything falls off.
Then some of the boards that have gold plating (some sound and video cards are all gold plated) got to sodium hydroxide bath to remove protective coating.
Then I take
3 L of distilled or deionized water, add
500 ml of 98% sulphuric acid, and
300 ml of Nitric acid
and put everything that has a bare metal on it into a solution. The solution should dissolve 600g of copper.
The reaction is pretty slow but with no fumes (very faint smell of nitrogen dioxide), in 3-4 day the solution turn into very nice blue colour (copper sulfate CuSO4) with fold flakes and some other metals depositing at the bottom.
After filtration (pretty hard to do) and removal of values, I boil the solution till only 30% of the liquid is left. A few hours later I have nice blue CuSO4 crystals and solution turns to very very light blue (almost clear).
I plan to extract copper from CuSO4 via electro wining, and as far as I understand I would need Platinized Titanium or Lead Oxide anode to recover the copper.