Non-Chemical diluted nitric vs weak lye

[meng2k7]

hi!

anyone tried this method of recovering Au from cpu pins?

i accidentally discovered this method week ago when i was trying to process pins from 486's, this is what happened.

1. dilute nitric (WATER 1st then ACID)(1 part nitric : 8 parts tap hot water), until no reaction occur
2. washed 3 times in boiling water
3. soak 3 minutes in lye with agitations
4. washed 3 times in boiling water
5. repeat this process until all the base metal dissolved.

8) 8) 8)

u can reuse the lye again and again, just make sure of good washings, and also the good thing was your nitric is neutralized after the process.

i'll post the pictures in my next post. thank you very much.

 

[goldsilverpro]

meng2k7,

What is the purpose of the lye? Offhand, I see no reason for it.

If you use enough nitric solution to start with, you should be be able to dissolve all the base metals the first time through. A liter of concentrated nitric will dissolve about 240 grams of copper, or a little more. The 8/1, water/nitric solution would dissolve about 27 grams of copper per liter. A less diluted nitric would require less total solution, of course. To avoid handling so much solution, I would use about a 3/1 dilution, or less.

My favorite way to do this would be to cover the pins with the hot water and then add concentrated nitric in small increments and allow each nitric addition to almost completely react before adding more. When an addition of nitric produces no reaction, all the base metal should be dissolved. Before the solution cools, make sure the water content is at least equal to the amount of nitric added. Otherwise, the copper nitrate will crystallize. If crystals do form, they are easily dissolved by adding more hot water and stirring.

The old general rule of "adding the acid to the water" was primarily put into place for such very strong acids as sulfuric or phosphoric, due to the tremendous heat generated when combining them with water. For HCl or HNO3, water can be added to the acid with little or no danger. The nitric/water combination will heat up a little, but not much. Of course, gloves and a full face shield should be used when pouring or mixing any chemicals.

 

[meng2k7]

meng2k7,

What is the purpose of the lye? Offhand, I see no reason for it.

hi chris!

the purpose of using lye is to dissolve the formed protective oxides from the plated items.


but as you said, to make the things go simple, its just hot water. :lol: :lol: :lol:


thank you very much sir!