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JohnGinto

Member
Joined
Jun 24, 2018
Messages
8
Hello all,
I am new to the community.
I usually recover scrap copper, aluminium and brass from electronic waste for a hobby. However I have began recovering gold plated parts from computers etc...
I have a strong addiction to gold so I am hoping to recover some. This is intended as a hobby and not to make money. I'm a keen learner and have been reading some materials from the net. Have also read Hoke's book and some other.
So far I have been successful in leaching the gold from the parts. However I failed my first Aqua Regia gold drop.
I purchased some SMB and added it to my solution of
150ml HCL and 50ml nitric. I used Urea to kill off the nitric first. I added 2tsp of SMB, it reacted but only for a second or so then nothing. I let sit for a day but nothing dropped. So I used a copper pipe to cement the gold.
On Hoke's book she states to boil away the nitric with the addition of sulfuric acid into a syrup avoiding a crust.
So I followed this method, however the yield was so minimal. I think i lost some values in the boiling off part.
I recently purchased copperas with the intent of using it on my next batch. I would appreciate any advice on how to use it correctly aswell as any advice on how to properly precipitate gold from Aqua regia.
Cheers,
Johno
 
Welcome to the forum.

You mention that you leached some gold from parts, but the yield was minimal. You didn't mention how many parts and what type of parts. Gold plating can be disappointing because it looks like a lot on the part, but there's really very little there. You may have lost some gold "boiling" your AR, but you may have recovered all there was.

You want to evaporate the solution, not boil it. Urea is an older way of trying to eliminate excess nitric, but it's not fully effective depending on how much excess you used. Sulfamic acid is preferable.

Most people dissolve their copperas in a minimal amount of water, add a bit of HCl, then filter the solution to remove any sediment. Then add the copperas solution to the AR after it has been deNOxed.

Dave
 
Next time, don't premix the aqua regia. Cover the material with about 25% more HCl than you predict you'll need, heat to about 140F, and then add about 1/4 of the total nitric that you predict you'll need, After the reaction subsides, give it a gentle stir and add a little more nitric. Repeat until a small addition of nitric produces no reaction, then, add no more nitric. Get it a little hotter and heat for about 15 minutes.

This takes a little practice and patience, but, if done right, you'll never have to use urea or sulfamic acid or boil the solution down, as in Hoke, to eliminate extra nitric, because no extra nitric was used. Therefore, the SMB should drop the gold with no problem. Nearly every longtime member uses this technique, or a variation of it. It truly works well.
 
Hello, although you have well described what you did, it is not clear whether you removed the base metal or put the gilded parts directly in AR.
 
Hello all,
Thank you for the inputs, much obliged...
I leached two different materials.
One was the circuit boards from cell phones and other gold bearing boards. I trimmed them all to just the gold bearing parts. I used acid/ peroxide method over a bubbler. The other were the good plated pins and other miscellaneous items. I removed any solders attaches with a cutter and cutting out the none plated areas. This batch I soaked in a nitric acid bath to dissolve the base metals. Once I had filtered the materials I placed both in the AR together. There was about 150 grams of plated materials and just under 500 grams of circuit boards.
The yield after cementing with copper was less than a gram that my scale will not read.
I am doing another batch at the moment and will follow the inputs you guys have suggested. I really want to make a successful drop with SMB from AR. I find it exciting watching/ hoping for a reaction with a result.

Cheers,
John
 
Yeah, so, by the number you are talking about, it is not surprising that you didn't really get any Gold. There are many different types of Gold plating, ENIG which you see mostly on IT gear is super super thin, have a look at this video: https://www.youtube.com/watch?v=iav_KH0PEZY&t=1s It does a good job of showing the difference between the Gold plating thickness on various parts.

You really want to start at the beginning and get yourself at least 1lB (0.5kg) of closely trimmed fingers from RAM, this will give you a couple of grams if you work carefully. Usually after they master the process with Gold fingers, people tend to move onto recovering bond wires from ICs.

E-waste gold recovery is a long hard road, but very rewarding once you are holding your first ounce.
 
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