IC chip process without sulfuric acid

[GoldUser]

Hello,

I have a few kg of ic chips and now I'm trying to process them.
The Problem is in my country I'm just able to buy HCl/Peroxide/Bleach for my refining.
Until now I did not find any processes without sulfuric acid.
I looked into making it myself but it's kind of a pain in the as because even precursers are not legal right here.
If someone had some advice I would really appreciate it.

Thanks and Greets
David

 

[MicheleM]

Sulfuric acid is dangerous and not necessary unless if your goal is to hack the microprocessor (but in this case fuming nitric acid is better). To recover gold you can use the "Incineration/ pyrolization method" or simply mortar and pestle. There are different ways to avoid the spreading of harmful dust and fumes.

 

[GoldUser]

Sulfuric acid is dangerous and not necessary unless if your goal is to hack the microprocessor (but in this case fuming nitric acid is better). To recover gold you can use the "Incineration/ pyrolization method" or simply mortar and pestle. There are different ways to avoid the spreading of harmful dust and fumes.

Thanks for the fast response.
I do not have access to nitric acid in my country.
Would it work to ash and disolve the gold with HCl and Chlor from Sodiumhypochloride?
David

 

[MicheleM]

Yes, first you have to pan gold from the pulverized/hashed IC chip. The Gold extracted from pulverized IC (mortar and pestle , very tough work to do ) is gold dust very easy to dissolve; the gold extracted from hashed IC chips is in form of tiny wires, they are difficult to dissolve with HCl+bleach but in the end you can

 

[Geo]

 

[Geo]

 

[Geo]

 

[orvi]

Incinerate them and you will be fine. On my opinion the sulfuric acid ashing is unnecessarily dangerous and expensive. Burning the chips is much easier and you do not produce gallons of acidic waste.

Key is to incinerate the chips to just ashes - you need to have plenty of oxygen around to make them crispy grey-white, and not grey-black still inside. You must get rid of all carbon if you intend to leach the ashes.

Sifting and panning will recover most of the gold, but certainly not all. It is a nice thing for people who do not want to get involved in "chemicals", just to burn and sluice/pan the material.

 

[Liquidau]

Thanks Geo, I have the exact same cement mixer and run it in a similar fashion, using steel balls and bolts. I tried to use magnetic separation after incinerating but before milling, but found that too much good stuff got stuck on the iron parts. So now I do it after. I also try to do a very thorough incineration the first time (in a furnace) so as to avoid having to do it again, although there’s always something that needs to be reburned and I accumulate enough to then do that. I also have a blue bowl and a gold cube for gravity/centrifugal separation, but congrats to you for the cheaper and effective “poop chute”.
My dilemma is still the next step—-acid washing, leaching, and AR, versus smelting and refining. I’ll be interested to see your next steps, and to hear what you do, and also get input from the Forum. I’m ramping up to process anywhere from 2 to 20 pounds a day of chips (from 100 to 1,000 lbs of boards per day.)
Cheers!
Len

 

[orvi]

Thanks Geo, I have the exact same cement mixer and run it in a similar fashion, using steel balls and bolts. I tried to use magnetic separation after incinerating but before milling, but found that too much good stuff got stuck on the iron parts. So now I do it after. I also try to do a very thorough incineration the first time (in a furnace) so as to avoid having to do it again, although there’s always something that needs to be reburned and I accumulate enough to then do that. I also have a blue bowl and a gold cube for gravity/centrifugal separation, but congrats to you for the cheaper and effective “poop chute”.
My dilemma is still the next step—-acid washing, leaching, and AR, versus smelting and refining. I’ll be interested to see your next steps, and to hear what you do, and also get input from the Forum. I’m ramping up to process anywhere from 2 to 20 pounds a day of chips (from 100 to 1,000 lbs of boards per day.)
Cheers!
Len

My experience is that with scaling up the operation, you want to get rid of hydrometallurgy, if possible. Gravity separation is the easiest thing to do first. You can get rid of 2/3 of the ashes and practically all the stuff without losing gold in tailings.
Sifting and panning give you most of the gold. The rest of the still gold containing tailings could then be smelted, if you have appropriate furnance for doing it on quantity cheaply (likely natural gas fueled for cost efficiency). That will go pretty easy, bit of collector metal, flux and it should be a good recovery. Remains of the ICs are practically plain silica sand, so fluxing it out should be relatively easy thing.
Moreover, you can mix the tails with flux and litharge and carbon directly, in "fire assay" fashion, assuring very good contact of the material with collector metal.

For magnetic material, there is also the possibility of molten lead/bismuth stripping (since the gold is on the surface of the contacts), but I would be worried about recovery efficiency since the big surface area and trapping the lead on the pieces of metal. This approach is very appealing to me, because you will skip the dissolution step = eliminating the gallons of AP waste. If I had enough material to play with, I will definitely try this out. With high enough temperature, you can do multiple smaller batches with same lead/bismuth bath, and only then after multiple strippings proceed to cupellation.

 

[Yggdrasil]

Just out of the top of my head.
You will always loose some, with this method.
Even if your capture during gravity separation is perfect.
There are small ponits "welded" to the connector points (magentic).
When grinded, the gold connector wires get quite mangled,how sure are you that your technique and skills will collect it all?
I feel that incineration and a slow acid BM dissolution method will be better.
I have seen comments, that they throw the magnetics to rust away to collect the last bits.

 

[Alondro]

I see people mentioning 'collector metal' often with the smelting. Unless you plan to use bismuth, it must refer to lead. Now, that means you must also cupel the lead away. I find that FAR more potentially dangerous for an amateur than sulfuric acid. Lead will stay in your body for YEARS if you inhale the fumes created. Sulfuric acid may be very reactive, but the elements composing it: hydrogen, oxygen, and sulfur are non-toxic.

It's the difference between acute chemical burns, and chronic health hazards. Both are potentially very dangerous, but I just prefer to deal with the acid, which I understand very well from my days working organic chemistry.

 

[Geo]

In my experience, when you use a sluice, whether it's a cheap piece of pipe or consumer brand sluice, You will not collect all the metal in one pass. It takes multiple passes before you can't see visible metal in the rifles. I didn't show everything, much like all youtube videos. After grinding, I classify the material. First, through 1/4" hardware cloth. This gets most chips that didn't incinerate well or any ceramic chips that snuck their way in. Then I place a piece of fiberglass window screen. Not sure of the mesh size but it will catch all but the smallest leads. The final screen is a #100 mesh classifier that sits on a 5 gallon bucket. Bond wires will easily fit through 100 mesh but most leads will not. Anything that will fit through the window screen but not through the 100 mesh gets re-milled. Magnetic separation. I keep this material and make ferrous sulfate with it as such as I can to drop gold from dirty solutions. Plus, I recover the small amount of gold in the magnetic part. The material is leached in nitric acid and a small amount of sulfuric acid in case any iron made it through the magnet. Again, from my experience, before the nitric acid leach, the material will have a fair amount of copper and silver. Save all leaches to reclaim the silver. I acquired a "Magic Gold Wheel" a few years ago and have been using it since. After you get all of the troublesome metals out, even with the small amount of silica and maybe a little carbon, you get a nice golden solution when dissolving the gold.
Just by observation, by the time you get to the magnetic separation, there is enough copper and silver to direct melt the material left and leach the resulting bead. I would add a few grams of silver just to be on the safe side.

 

[orvi]

I see people mentioning 'collector metal' often with the smelting. Unless you plan to use bismuth, it must refer to lead. Now, that means you must also cupel the lead away. I find that FAR more potentially dangerous for an amateur than sulfuric acid. Lead will stay in your body for YEARS if you inhale the fumes created. Sulfuric acid may be very reactive, but the elements composing it: hydrogen, oxygen, and sulfur are non-toxic.

It's the difference between acute chemical burns, and chronic health hazards. Both are potentially very dangerous, but I just prefer to deal with the acid, which I understand very well from my days working organic chemistry.

Yes, that is true. Cupelling lead is relatively hazardous procedure. On the other hand, in 180°C sulfuric acid, all the organic junk we want to avoid with proper incineration is evolved to the air. Unless you are wet ashing in the fume hood, this is nowhere safe. Quite a bit of volatile hazardous stuff can be evolved during the process, and I do not mean the stuff arising from the acid, but from the decomposing plastic.

On bigger scale, there are also methods how to scavenge the gold from the lead without direct need for cupelling (similar to Parkes process). And recycling the same lead (with leftover traces of gold) for the next batch. But this is more for the production, not for amateur with two or three few kilo batches.

I agree, that for amateurs, AR leaching of the incinerated remains is much easier than going with smelting. But all big players doing not only the IC chips, but whole trucks worth of PCBs are doing it by means of pyrometallurgy.

 

[orvi]

Just out of the top of my head.
You will always loose some, with this method.
Even if your capture during gravity separation is perfect.
There are small ponits "welded" to the connector points (magentic).
When grinded, the gold connector wires get quite mangled,how sure are you that your technique and skills will collect it all?
I feel that incineration and a slow acid BM dissolution method will be better.
I have seen comments, that they throw the magnetics to rust away to collect the last bits.

With proper incineration with plenty of accessible oxygen, the chips will disintegrate very easily and there is no need for grinding them. Simply stirring the remaining ashes with steel rod in a steel can will produce fine powder mixed with silicon dies and legs. Thick ones require some additional time in the furnance to get there.
Going through fine sieve, you separate the legs and dies. Magnet will pick up the legs. With gentle manipulation, nothing end up mangled.
But I understand that it could be more convenient to just grind them and then leach. I have done it multiple times this way and it works OK.
From my point of perspective, it is just about the scale. If I have dozens of kilos to process, I will definitely try to get rid of dissolution steps and focus on pyrometallurgy.

 

[kurtak]

Key is to incinerate the chips to just ashes - you need to have plenty of oxygen around to make them crispy grey-white, and not grey-black still inside

Not quite true - You only need to turn the chips to "complete carbon in the first (incineration) part of the process - I have posted about this "several" time here on the forum -------------

https://goldrefiningforum.com/threads/pyrolysis-reactor.22581/#post-237092
Gold inside chips (black, flatpacks - not CPU)

My post is about 2/3 down on the above page

https://goldrefiningforum.com/threads/unable-to-precipitate-gold.30722/page-2#post-322226
For what it is worth I used to process 500 - 600 pounds (225 -275 kilos) per year in 50 - 60 pound (23 - 28 kilo) batches

A 50 - 60 pound batch of carbonized IC chips will give you (about) 1/2 - 2/3 of a 5 gallon (20 liter) bucket of fine milled (80 minus mess) carbon --- that (carbon) can then be reduced to (about) a 1/2 of a coffee can of concentrates (panning or concentrator table

It's the carbon in these concentrates that you want to "re-incinerate" insuring the carbon is turned to complete ash before taking the concentrates to leaching or smelting

You just want to make sure you get "complete" carbonization of the chips in the incineration step so that you get very near complete (if not complete) milling during the milling step

Kurt

 

[kurtak]

I see people mentioning 'collector metal' often with the smelting. Unless you plan to use bismuth, it must refer to lead.

Or you can use silver (or copper) as your collector metal

Kurt

 

[kurtak]

I agree, that for amateurs, AR leaching of the incinerated remains is much easier than going with smelting.

I agree

The problem for some people (in some countries) is that can't get nitric acid for making AR & like in the case of the OP they can't even get nitrates (like sodium nitrate or potassium nitrate) for making poor man's AR

Which is why he asked -------

The Problem is in my country I'm just able to buy HCl/Peroxide/Bleach for my refining.

I have always had nitric so I can't really speak to using H2O2 or chlorine (bleach) for dissolving gold bonding wires --- I only know that they will both dissolve gold foils (which are VERY light/thin gold)

Gold bond wires are a much thicker/heavier gold - so I "assume" to dissolve gold bond wires with H2O2 you would need a HIGH concentrate H2O2 --- then (because I believe you would end up with LOTS of free/excess oxidizer) I am not sure how you would go about ridding that oxidizer in order to drop the gold

The problem with chlorine (bleach) is keeping the chlorine in solution long enough & in high enough concentration to dissolve the bond wire - it works fine on foils - but bond wires (being heaver) is a different story

Here is a part of what the OP said that I don't quite understand -----------

Until now I did not find any processes without sulfuric acid.
I looked into making it myself but it's kind of a pain in the as because even precursers are not legal right here.

It sounds like he has looked into making his own nitric using sulfuric with nitrates (sodium or potassium nitrate) but he can't get some - or any of those things ether ?

GoldUser - is that right ? --- if so - is it only some of that stuff you can't get - or all of it you cant get

Kurt

 

[kurtak]

Remains of the ICs are practically plain silica sand, so fluxing it out should be relatively easy thing.

Orvi - per the bold print - the fillers in the black epoxy are for the most part FINE ceramics (like alumina powder) so not silica sand

Also the actual IC chip/die is "silicon" - silicon & silica are two different things - silicon will actually alloy with gold whereas silica does not & so is used as a (acidic) flux ingredient for slagging of metal oxides - silica will also dissolve silicon

Therefore - after milling IC chips & because you will end up small/fine particles of silicon in the concentrates you have to actually add some silica to your flux to dissolve & slag that silicon off or it can end up alloyed with your gold

IF (the BIG IF) you get a GOOD HIGH gold concentrate of bond wires you can direct smelt the gold without a collector metal - but - if you use a borax/soda ash flux (with a "bit" of fluorspar for thinning) you will likely end up with a gold/silicon alloy --- adding some actual silica to the flux/smelt will slag the silicon off

Concentrates from N/S bridge BGAs (the black epoxy top only) is a good example of where you can get a GOOD HIGH gold concentrate that can go to direct smelt without a collector

Kurt

 

[Geo]

To remove excess H2O2 or hypochlorite from solution is fairly easy and straightforward. Heat the solution to a low boil for a prolong period of time. Hypochlorite is destroyed at around 210°F and H2O2 is destroyed at around 303°F. Higher concentrations may take longer. Hair bleach is about the highest concentration a normal consumer grade is about 12% concentration but there are ways to get 20% concentrations if you know where to look.

In my experience, these oxidizers are too weak to effectively dissolve massed bonding wires. In all the years I've been doing this, I have never really been able to isolate just the gold bond wires from copper and silver. The copper is problematic without nitric acid or nitrate substitute. The copper, being more reactive than gold, tends to dissolve first. Using a weaker oxidizer would takes days of diligent oversight and small additions of oxidizer because the leach needs to be hot and heat destroys the oxidizer. You are only benefitting from a portion of the oxidizer used.