IC chips gold recovery

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sayf

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Sep 1, 2020
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Hello dear refiners, i hope you are all fine.
I have a good source for E-waste so i can collect good amounts of ic chips.
most of the E boards i usually get are communication boards.
The first patch of ic chips i did was about 20 kg
I incenerated the chips, powdered them then i carefully washed the powder to get rid of epoxy, then i get rid of the basic metals using 1-1 diluted nitric acid
I precipitated the silver from the nitric using nacl solution and got good amount of silver exceeding 100 grams
For the rest of the process, i washed the leftovers using distilled water and added aqua regia to the leftovers, i made sure that the amount of aqua regia is enough to dissolve all the metals and i wated until the reaction is completely done
I nutrelized the nitric with sulphamic acid and precipitated gold using ferrous sulphate
And got only 4 grams of gold, duh i was shocked because i expected more than 40 grams of gold.
the second patch was also 20 kg and was done using same procedure and got similar result
Do you think this result is logical dear experts?
The electronics i deal with are old and mostly simens and alcatel
What i am missing here ?
REGARDS
 

Yggdrasil

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Hello dear refiners, i hope you are all fine.
I have a good source for E-waste so i can collect good amounts of ic chips.
most of the E boards i usually get are communication boards.
The first patch of ic chips i did was about 20 kg
I incenerated the chips, powdered them then i carefully washed the powder to get rid of epoxy, then i get rid of the basic metals using 1-1 diluted nitric acid
I precipitated the silver from the nitric using nacl solution and got good amount of silver exceeding 100 grams
For the rest of the process, i washed the leftovers using distilled water and added aqua regia to the leftovers, i made sure that the amount of aqua regia is enough to dissolve all the metals and i wated until the reaction is completely done
I nutrelized the nitric with sulphamic acid and precipitated gold using ferrous sulphate
And got only 4 grams of gold, duh i was shocked because i expected more than 40 grams of gold.
the second patch was also 20 kg and was done using same procedure and got similar result
Do you think this result is logical dear experts?
The electronics i deal with are old and mostly simens and alcatel
What i am missing here ?
REGARDS

First of all it is NOT NEUTRALIZING THE NITRIC, it is decomposing, out gassing, destroying or similar.
Because what you do is to change the Nitric and NOx to other harmless (for the coming reactions) substances.
We have replied to you in this matter several times.

Why did you have to get rid of epoxy, was it not completely incinerated?
Was ALL the metals dissolved after AR?
Did you test the solution after Copperas?
 

kurtak

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John Day Oregon
First off - if you are processing "a good mix" (all types) of ICs you should most certainly get MUCH more the 4 grams gold from 20 kg chips

To put it in perspective - if you processed NOTHING BUT 20 kg of PROMS (the very lowest grade of chips) then yes you would only get (about) 4 grams

But a true "mix" of chips should give you better (much better) results

This thread should give you "an idea" of what to expect from "each type" of chip(s)


That said ------
I incenerated the chips, powdered them then i carefully washed the powder to get rid of epoxy, then i get rid of the basic metals using 1-1 diluted nitric acid

Per the bold print - this IMO (In My Opinion) is your first mistake !!!

You first NEED to get rid of the base metals BEFORE washing of the ash/carbon (after incinerating & milling/crushing) --- as well as larger pieces of broken silicon dies

If you don't get rid of the Kovar &/or copper legs/wires (as well as silicon dies) in the carbon/ash BEFORE trying to wash off the carbon/ash - those Kovar/copper legs/wires & large pieces of silicon dies will cause interference in the washing process which will in turn cause the VERY fine gold bonding wires to wash off along with the carbon/ash

So the proper steps are as follows ------

1) incinerate to turn the epoxy to carbon/ash

2) mill/crush the carbon/ash (incinerated chips) to fine powder

3) sift the milled chips (carbon/ash) through (at least) 80 mesh (or 100 mesh) screen which will remove the "larger" Kover/copper & larger pieces of silicon dies --- smaller Kovar/copper wires (& fine crushed silicon) will go through the sifting screen - so -----

4) spread out the (fine milled) carbon/ash in a very thin layer & run a "weak" magnet over it to remove any Kovar that made it through the sifting screen --- there will still be fine copper in the carbon/ash which you need to get rid of

Depending on how much copper is in carbon/ash you may have to ---------

1) leach/dissolve the copper out of the carbon/ash BEFORE washing the carbon/ash off to collect/concentrate the gold bond wires --- or ------

2) you MAY get away with doing a "pre-wash" of the carbon ash - to "reduce" the amount of carbon/ash before leaching/dissolving the copper - then a second wash to collect/concentrate the bond wires

There are a couple different method to the above step 2 depending on the amount of copper in the carbon ash

Bottom line - you want to get rid of as much "junk" from the carbon/ash BEFORE washing the carbon/ash to concentrate the bond wires for final leaching or smelting

The trick is leaving the gold in the carbon/ash during the process of removing the junk

if you don't remove the junk (at least the LARGE Kovar/copper/silicon) you will most certainly wash gold (bond wires) out with the carbon/ash

Kurt
 

Martijn

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Hello dear refiners, i hope you are all fine.
I have a good source for E-waste so i can collect good amounts of ic chips.
most of the E boards i usually get are communication boards.
The first patch of ic chips i did was about 20 kg
I incenerated the chips, powdered them then i carefully washed the powder to get rid of epoxy, then i get rid of the basic metals using 1-1 diluted nitric acid
I precipitated the silver from the nitric using nacl solution and got good amount of silver exceeding 100 grams
For the rest of the process, i washed the leftovers using distilled water and added aqua regia to the leftovers, i made sure that the amount of aqua regia is enough to dissolve all the metals and i wated until the reaction is completely done
I nutrelized the nitric with sulphamic acid and precipitated gold using ferrous sulphate
And got only 4 grams of gold, duh i was shocked because i expected more than 40 grams of gold.
the second patch was also 20 kg and was done using same procedure and got similar result
Do you think this result is logical dear experts?
The electronics i deal with are old and mostly simens and alcatel
What i am missing here ?
REGARDS
Aluminum bonding wires in most of them in stead of gold maybe? Did you sort any of the IC's or did you process everything together?
Incinerate a couple and inspect with a jewelers loupe or microscope. Saves a lot on burning waste, and consuming base metals with nitric to get 'worthless' aluminum wires.
How did you minimize the NO2 emissions?

20kg's of chips burned. Can you share pictures of your pyrolyzing and incinerating setup?
Did you have different results with these types of chips before or with any chips?
I'm trying to asses your level of experience in keeping the toxic stuff out of your lungs and our environment.

Edited for spelling.
And:
I know you tube is by-passing us in this but i really must warn you for the dangers of burning epoxy, PVC, and other plastics.

To me it sounds like you don't fully grasp the whole process yet, but felt confortable enough processing a bucket full of mixed stuff you've never done before.

Experiment small, you'll have small mistakes to clean up with big experience steps.
Once you have it down, scale up. Slowly.

Martijn.
 
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kurtak

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Experiment small, you'll have small mistakes to clean up with big experience steps.
Once you have it down, scale up. Slowly.
I agree !!!!

Can you share pictures of your pyrolyzing and incinerating setup?
It would also be good to see pics of the actual chips (at least a small sample of the "types" of chips) & as well pics of your washing set up

Kurt
 

Martijn

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It would also be good to see pics of the actual chips (at least a small sample of the "types" of chips) & as well pics of your washing set up

Kurt
Yes. I agree.

But he may have lost gold due to inexperience, and mistakes in processing.

Then I would like to encourage him to maximize the efficiency of his entire process, by looking at what is worth processing and what simply is a waste of
time and resources.
It's like finding a rich ore and mixing it with workshop grindings before recovering values.
Junk in, junk out, so don't add any more junk.
It's like inquarting gold plated copper with more copper just to dissolve the whole thing...

First stip that 100 feet of overburden before you sluice. Saves on ⛽
 

kurtak

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Then I would like to encourage him to maximize the efficiency of his entire process, by looking at what is worth processing and what simply is a waste of
time and resources.
I agree - which is why pictures of the different stages/step of his process would be good to see

Pics off -----

1) the chips them selves

2) incineration set up

3) milling/crushing set up

4) sifting/magnetic separation process

5) washing setup/process

6) leaching process

Kurt
 

orvi

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If leaching is applied on large bulk of fine ground ash/silica powder, great care should be taken to burn ALL of the carbon from it. Carbon has quite concerning loading capacity for adsorption of dissolved metals, particularly gold.
I like to take red hot pyrolyzed/half-incinerated remains of ICs out of the furnance and spread them onto some plate (old baking pan etc.) which is insulated to retain heat from the bottom. Then I take heatgun and blow hot air on them to properly burn out all of the carbon to be left with only slightly greyish material which easily crumbles to the powder when simply shaken in some container.

Thing is, inside the furnance when heating with burner, there is always low oxygen atmosphere due to this obvious fact. Taking them out and spreading them into some thin layer assures air (not combusted gasses) will reach them properly and finish the incineration relatively quickly.

Alternatively, you can do whole incineration with heat gun instead of the burner, if it can get to like 600°C. Air isn´t deprived of oxygen (like with torch), so when the temperature rise and burning kicks in, it is burning much much cleaner than with torch heating. But also afterburner should be installed anyway to deal with some remains of uncombusted material. Of course, I am speaking about incineration inside gas furnance.

With bulk of the ashes, sifting and careful panning/sluicing is an option. But if it isn´t very big volume, I like to briefly remove magnetics out and smelt it all down. Powder is practically plain silica, so CaO flux, induction furnance, 1300-1400 °C and it is done conveniently and quantitatively.
 

sayf

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Messages
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First off - if you are processing "a good mix" (all types) of ICs you should most certainly get MUCH more the 4 grams gold from 20 kg chips

To put it in perspective - if you processed NOTHING BUT 20 kg of PROMS (the very lowest grade of chips) then yes you would only get (about) 4 grams

But a true "mix" of chips should give you better (much better) results

This thread should give you "an idea" of what to expect from "each type" of chip(s)


That said ------


Per the bold print - this IMO (In My Opinion) is your first mistake !!!

You first NEED to get rid of the base metals BEFORE washing of the ash/carbon (after incinerating & milling/crushing) --- as well as larger pieces of broken silicon dies

If you don't get rid of the Kovar &/or copper legs/wires (as well as silicon dies) in the carbon/ash BEFORE trying to wash off the carbon/ash - those Kovar/copper legs/wires & large pieces of silicon dies will cause interference in the washing process which will in turn cause the VERY fine gold bonding wires to wash off along with the carbon/ash

So the proper steps are as follows ------

1) incinerate to turn the epoxy to carbon/ash

2) mill/crush the carbon/ash (incinerated chips) to fine powder

3) sift the milled chips (carbon/ash) through (at least) 80 mesh (or 100 mesh) screen which will remove the "larger" Kover/copper & larger pieces of silicon dies --- smaller Kovar/copper wires (& fine crushed silicon) will go through the sifting screen - so -----

4) spread out the (fine milled) carbon/ash in a very thin layer & run a "weak" magnet over it to remove any Kovar that made it through the sifting screen --- there will still be fine copper in the carbon/ash which you need to get rid of

Depending on how much copper is in carbon/ash you may have to ---------

1) leach/dissolve the copper out of the carbon/ash BEFORE washing the carbon/ash off to collect/concentrate the gold bond wires --- or ------

2) you MAY get away with doing a "pre-wash" of the carbon ash - to "reduce" the amount of carbon/ash before leaching/dissolving the copper - then a second wash to collect/concentrate the bond wires

There are a couple different method to the above step 2 depending on the amount of copper in the carbon ash

Bottom line - you want to get rid of as much "junk" from the carbon/ash BEFORE washing the
First off - if you are processing "a good mix" (all types) of ICs you should most certainly get MUCH more the 4 grams gold from 20 kg chips

To put it in perspective - if you processed NOTHING BUT 20 kg of PROMS (the very lowest grade of chips) then yes you would only get (about) 4 grams

But a true "mix" of chips should give you better (much better) results

This thread should give you "an idea" of what to expect from "each type" of chip(s)


That said ------


Per the bold print - this IMO (In My Opinion) is your first mistake !!!

You first NEED to get rid of the base metals BEFORE washing of the ash/carbon (after incinerating & milling/crushing) --- as well as larger pieces of broken silicon dies

If you don't get rid of the Kovar &/or copper legs/wires (as well as silicon dies) in the carbon/ash BEFORE trying to wash off the carbon/ash - those Kovar/copper legs/wires & large pieces of silicon dies will cause interference in the washing process which will in turn cause the VERY fine gold bonding wires to wash off along with the carbon/ash

So the proper steps are as follows ------

1) incinerate to turn the epoxy to carbon/ash

2) mill/crush the carbon/ash (incinerated chips) to fine powder

3) sift the milled chips (carbon/ash) through (at least) 80 mesh (or 100 mesh) screen which will remove the "larger" Kover/copper & larger pieces of silicon dies --- smaller Kovar/copper wires (& fine crushed silicon) will go through the sifting screen - so -----

4) spread out the (fine milled) carbon/ash in a very thin layer & run a "weak" magnet over it to remove any Kovar that made it through the sifting screen --- there will still be fine copper in the carbon/ash which you need to get rid of

Depending on how much copper is in carbon/ash you may have to ---------

1) leach/dissolve the copper out of the carbon/ash BEFORE washing the carbon/ash off to collect/concentrate the gold bond wires --- or ------

2) you MAY get away with doing a "pre-wash" of the carbon ash - to "reduce" the amount of carbon/ash before leaching/dissolving the copper - then a second wash to collect/concentrate the bond wires

There are a couple different method to the above step 2 depending on the amount of copper in the carbon ash

Bottom line - you want to get rid of as much "junk" from the carbon/ash BEFORE washing the carbon/ash to concentrate the bond wires for final leaching or smelting

The trick is leaving the gold in the carbon/ash during the process of removing the junk

if you don't remove the junk (at least the LARGE Kovar/copper/silicon) you will most certainly wash gold (bond wires) out with the carbon/ash

Kurt
Thank you very much kurt, you are alright and most likely i lost the gold bonding wires during the wash step.

Because i just finished a patch of 10 kg ic chips of almost same type as the above 20 kg patch using chemical wet ashing method and got 19 grams of gold
 

kurtak

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If leaching is applied on large bulk of fine ground ash/silica powder, great care should be taken to burn ALL of the carbon from it. Carbon has quite concerning loading capacity for adsorption of dissolved metals, particularly gold.

This is correct - dissolved metal ions like to "load" (absorb) on fine particles of carbon which will lead to lost gold in the leaching process if the fine carbon is not turned to actual ash before leaching the gold from the concentrates

In fact "carbon loading" is one way to recover dissolved metal ions from a solution - but that is a whole different process for a whole different discussion
I like to take red hot pyrolyzed/half-incinerated remains of ICs out of the furnance and spread them onto some plate (old baking pan etc.) which is insulated to retain heat from the bottom. Then I take heatgun and blow hot air on them to properly burn out all of the carbon

As the saying goes --- there is more then one way to skin a cat ;) :)

That said - you do not need to be concerned with turning the whole chips to ash - you only need to be sure that the chips are completely carbonized so that they can be milled to a fine powder (80 - 100 mesh)

Once the carbon is milled to a fine powder & after sifting & magnetic separation (as described yesterday) to remove the "large" pieces of Kovar/copper & broken silicon dies you can then go to the washing process to get you concentrates

Carbon that is milled to 80 (minus) mesh is very light weight & will wash off just fine - to give you the concentrates you are after

Yes - the concentrates are going to have carbon in them (as well as fine silicon & fillers used in the epoxy) but that is as simple as re-incinerating those concentrates to turn that small amount of carbon to ash before leaching the concentrates

IMO - it is much easier to just get the chips completely carbonized - milling the carbon - do the concentration process - then re-incinerate the concentrates to insure the carbon is turned to ash --- rather then trying to incinerate whole chips to complete ash before milling & concentrating

In fact - it is next to imposable to completely ash whole chips - especially if you are doing larger batches (20 - 30 kg) & or if you have thick chips (like PROMs &/or thick quads) in the mix --- you are likely going to end up with carbon in the concentrates anyway which means the concentrates will need re-incineration anyway

This is based on my doing 25 - 35 kg batches at a time with doing 200 - 300 kg of chips per year

Carbonize (completely) mill carbon to fine powder - sift/magnetic separation - concentrate - re-incinerate concentrates - leach (or smelt) concentrates

In other words - there is no need to be concerned about carbon when processing IC chips --- until you get to the point of leaching (or smelting) the concentrates

IMO

Kurt
 

kurtak

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Because i just finished a patch of 10 kg ic chips of almost same type as the above 20 kg patch using chemical wet ashing method and got 19 grams of gold
Per the bold print - IMO - only a fool would use that process - especially when trying to process chips in large batches with the wet ashing process

Yes I have used that process - one time - & I will NEVER do it again because I am not a fool

Learn to do it through the proper incineration process

Kurt
 

kurtak

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With bulk of the ashes, sifting and careful panning/sluicing is an option. But if it isn´t very big volume, I like to briefly remove magnetics out and smelt it all down. Powder is practically plain silica, so CaO flux, induction furnance, 1300-1400 °C and it is done conveniently and quantitatively.
Per the bold print - after milling the IC chips you end up with (at least some) silicon in the ash - silicon will in fact alloy with gold - so yes - if you are going to smelt you need to have lime in the flux to insure the silicon slags off & does not alloy with the gold --- it (lime) of course helps with the silica as well - the silica comes from the fillers used in the epoxy

Kurt
 

kurtak

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Some pics of when I was processing larger batches of IC chips - notice that the fine powder after milling is very near entirely fine carbon - which I did not concern myself with until after washing to get my concentrates
 

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kurtak

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Magnetic separation - note the carbon is spread very thin on a non magnetic SS sheet (sorry no pics of sifting)

I wrap a plastic bag around the magnet to make it easier to remove the Kovar that is stuck to the magnet by simply pulling the plastic away from the magnet when the magnet is loaded with Kovar
 

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kurtak

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After sifting & magnetic separation I run the fine carbon on my concentrator table to wash off most of the fine carbon

Most of the gold bond wires collect at the top of the table

Some carbon along with fine ground silicon & fillers from the epoxy as well what very few bond wires make it past the top of the table collect further down the table --- what collects on the table is your concentrates

20 - 25 kg of starting chips should give you (about) 1/2 to 2/3 of a 20 liter bucket full of fine milled carbon

when you are done concentrating you should end up with 3 - 4 cups (5 cups at most) of concentrates - which then need to be re-incinerated to ash the carbon

Sorry I only have pics of the bonding wires colleting at the top of the table but no pics of the silicon/filler/carbon that collects further down the table
 

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kurtak

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Please note Kurt’s use of gloves while using the magnet.
Yes - there is all kinds of nasties in that fine ash/carbon

Edit to add; - in fact I wear gloves in EVERY step of the process from incineration to the end product of the recovered/refined gold

Edit again to add; - when milling & handling the dry carbon you MUST also wear a good dust mask

There is ultra fine silica in the fine carbon powder & if you breath that ultra fine silica into you lungs it will more then likely result you getting silicosis - which you will not even know you have until years later


Kurt
 
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MicheleM

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Thank you for sharing your work @kurtak.
i have not more IC to have fun with so I can only appreciate this kind of pictures: good moments come back in my mind
 

sayf

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Finished product after all is said & done
Just a curious question, after milling the ic chips to a very fine powder and incinerating the black powder again to make sure that all carbon is gone, can i use aqua regia directly to dissolve all metals and after making sure that all metals are dissolved ill filter the solution and drop dirty gold with ferrous sulfate then ill purify the gold again using a second aqua regia dissolve and drop it with ferrous sulphate .
Is this possible ?
 
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