Chips and sodium hydroxide

[SapunovDmitry]

Good day to everyone.
Allright, here is the interesting one.
I have seen much videos on the youtube about lads boiling burned microchips and thus getting rid of silica sand. Then they process their stuff with conventional methods such as nitric/AR etc. So here is the question..... Is it FAKE from the beginning? Does anyone has a first hand experience with good yields in that process?
Here are my thoughts on the topic.
Guys burn chips and don't ge much of their gold blown out.- I think it is achievable since i have made my own analysis and it showed that one can burn chips in the presence of air after pyrolysis and get about 97-98% of the gold back. (Batch was equally divided and with one part being smelted directly while the other was processed with pyrolysis, burned to ash and then smelted."Physical" gold content in mg showed 96,4-99,3% coincidence.
Then guys put their chips in a stainless jar, put some sodium hydroxide and water (allright, they put ALOT of sodium hydroxide and little water) and some "magic" starts.
They boil it and claim to have a clear solution of sodium silicate and copper+gold wires at the bottm of the jar. I have tried it SO many countless times and NEVER,NEVER had a clear solution with sodium slilcate with no silica remaining at th bottom. It usually becomes a "powderlike" stuff similar to hydroxides (you know, when you put some strong alkali in the acidic solution with metal salts) instead of the clear soluion. The worst thing is that when i watch those chunks with my microscope there are gold wires conneced to them.
Since i know that at 950-1150 C silica combines with sodium carbonate and everything is cool since copper melts and slag formes i think that this process is possible in principle at some temperatures, but i have never heard of a person actually doing it with good yields.
P.S. By the way, shouldn't gold wires dissolve in strong alkali solutions at elevated temperatures?

 

[darinventions]

bud, I've done quite abit of research myself an I've never heard of gold desolving in (LYE) no matter how strong or hot,,there are some metals that will react with with LYE,the most commonly known is Aluminum, you may need to PM someone like Butcher or one of the other men who deal with circuit boards regularly an ask them to post on this matter...keep in mind they may be very busy...

 

[butcher]

I do not have any experience in this area so my thoughts on the subject are just that my thoughts.

Hydroxides will attack silica especially at higher temperatures, but to try and use that aspect to dissolve silica from CPU's or chips to me sounds to be a very dangerous and useless idea, I would not expect it to work worth a darn.
My thought it is just too much of a safety risk to even attempt it in some experiment I would strongly suspect to fail anyway.

Exception of this would be in smelting, where a flux is used with a component that would form silica/metal oxide slags, but sodium hydroxide would not normally be used in this case, where other more common fluxing agents or materials may be used, like sodium borate (Na₂B₄O₇-10H₂O), fluorspar (flurorite) (calcium fluoride CaF₂), Soda ash (sodium carbonate Na₂CO₃...

Gold will not oxidize easily, even in hot solutions of hydroxides, although gold hydroxide can be formed from gold solutions...

 

[solar_plasma]

In fact this is something I always wanted to try as a test with only a few chips only to see if this fine SiO2 powders will dissolve easily, but I believe butcher is right - NaOH is somewhat nasty stuff to deal with (I always use full face shield and goggles since I got a drop into my face when making soap) and it is pretty useless since panning works quite fine.

 

[börki]

Hello everybody,
I'm using 20% sodium hydroxide solution to substitute the thermal treatment of BGA chips as I have no chance to pyrolize.

This works only with BGA chips for me. Best results (in terms of getting the chips softish) are obtained when solder balls are removed, e.g. with hydrochloric acid.

Removing the solder balls little holes in the BGA package are left allowing the sodium hydroxide solution to get in contact with the silicon. My process is to boil the desoldered chips (batch size 2 kg) approx. 4h in the sodium hydroxide solution. If you want to try, please make yourself familiar with the safety instructions, as sodium hydroxide solutions are dangerous, especially when hot.

After cooling and thorough washing the BGA chips crack as easy as patato chips.
Now the chips can go into a household blender or a flour mill.

During this process you can observe that the silicon is converted to the silicates, it looks like small little white worms swimming in the liquid. My chips are loosing half of their initial weight due to this reaction.

I wanted to get rid of the rest of the silicon with a second treat of the crushed chips. Please note that the tiny silicon particles have a very big surface which leads to a vigorous reaction in sodium hydroxide solution already at room temperature. Hydrogen gas is instantly formed in very small bubbles leading to a foam which can spil over.

Take care and thanks to all for this amazing forum.
Börki