IC chips gold recovery

[kurtak]

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 ?

Per the bold print - short answer = yes (it's "possible")

Longer answer = it is NOT a good idea - in fact it is a VERY bad idea !!!

Why?

1) it will create a LOT of chemical waste !!! --- chemical waste that you absolutely DO NOT need to create !!!

2) Kovar - which is what most of the base metal in IC chip ash is - is VERY acid resistant & requires LOTS of heat for the acid to dissolve the Kovar

3) Even with HOT acid it will take longer (a LOT longer) to dissolve the Kovar out of the ash then the time it takes to pull the Kovar out of the ash with a magnet

Kurt

 

[sayf]

Per the bold print - short answer = yes (it's "possible")

Longer answer = it is NOT a good idea - in fact it is a VERY bad idea !!!

Why?

1) it will create a LOT of chemical waste !!! --- chemical waste that you absolutely DO NOT need to create !!!

2) Kovar - which is what most of the base metal in IC chip ash is - is VERY acid resistant & requires LOTS of heat for the acid to dissolve the Kovar

3) Even with HOT acid it will take longer (a LOT longer) to dissolve the Kovar out of the ash then the time it takes to pull the Kovar out of the ash with a magnet

Kurt

Thank you very much kurt, Here are the IC chips i mostly work with

 

[jphayesjr]

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 ?

Read Hoke's book

 

[goldeelox]

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

You using a Freddy dodge table

 

[BlackLabel]

If the amount of kovar/iron exceeds the ability of a plastic wrapped magnet, there are some magnets for gold prospectors and hardcore refiners :

From Keene Engineering:


https://www.keene.store/mm5/merchant.mvc?Screen=PROD&Product_Code=A28



https://www.keene.store/mm5/merchant.mvc?Screen=PROD&Product_Code=A28A
From Sona:


https://www.promusicalaska.com/stor...gnets/sona-8lb-black-sand-magnetic-separator/


https://www.promusicalaska.com/stor...nets/sona-16lb-black-sand-magnetic-separator/

 

[snoman701]

Hope you saved your ash. Your gold is still there. Just do what Orvi suggested. Put it all out in a thin layer and put it in a furnace at 650 deg C util your ash is a whitish purple.

However, if you used aqua regia on it, you should first wet it all with water that has a pH of 11 or so. This will keep your vaporization losses lower.

Once ashed out, you can use HCl with stepwise additions of nitric or peroxide to dissolve your gold. You'll lose some gold to the ash, just because you can never actually rinse it clean of values...but it's saveable.

Your gold is going to be too finely divided to be gravity separated at this point. That's the only reason I suggest going straight to chemical leaching.

 

[Rreyes097]

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.

Would an electric furnace work in a crucible?

 

[Yggdrasil]

Would an electric furnace work in a crucible?

I guess you mean the opposite?
Would a crucible work in an electric furnace?
Yes most small ones will come with a graphite crucible.

 

[Rreyes097]

I guess you mean the opposite?
Would a crucible work in an electric furnace?
Yes most small ones will come with a graphite crucible.

What I meant was can I put ic chips in the electric furnace crucible and paralyzing like that instead of torching them because the stank and the smoke is too much for the area I live in.

 

[Yggdrasil]

What I meant was can I put ic chips in the electric furnace crucible and paralyzing (pyrolizing) like that instead of torching them because the stank and the smoke is too much for the area I live in.

That is not pyrolizing, it is incineration.
Pyrolizing is heating it up without access to air until all volatile elements has evaporated and burnt up in a afterburner.
Usually this is done in an coal/gas furnace where the gases are lead into the heating burner,
this reduces the needs for fuel and will burn all gases completely eliminating smoke and smell.
The left overs has to be incinerated/roasted in air after to completely burn off the carbon residue.

 

[Rreyes097]

So i have those Ic chips that came off of the ram sticks. These chips (forgive me because I don't know the actual nes for these) so I have no real base metals to worry about. I have already washed them I'm hot HCl 3 times, then rinsed with water until my rinses were pretty clear. So which process do I need to do? Pyrolyzation or incineration? I tried to just burn a pan of them with a torch.
It let off far too much smoke of nasty smell. So what are my options at this point? Because I have quite a bit of them. About 900. Grams

 

[Yggdrasil]

So i have those Ic chips that came off of the ram sticks. These chips (forgive me because I don't know the actual nes for these) so I have no real base metals to worry about. I have already washed them I'm hot HCl 3 times, then rinsed with water until my rinses were pretty clear. So which process do I need to do? Pyrolyzation or incineration? I tried to just burn a pan of them with a torch.
It let off far too much smoke of nasty smell. So what are my options at this point? Because I have quite a bit of them. About 900. Grams

Both.
Pyrolizing to get out the volatiles, then incineration to burn off the carbon.
There are several threads dealing with this, even the hardware to do so.
Just search and read.

 

[DJPGold]

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)

https://goldrefiningforum.com/threa...ic-types-of-ic-chips-flatpacks-and-bga.22951/
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

Can you please clear up why we need to remove the magnetic materials before washing/rinsing off the carbon after milking?
A process that I’ve used quite a lot in the past is Incineration>milling>sieving>wetting,let settle for 30ish minutes>siphon and repeat>dry cleaned material in a stainless pot>magnetic separation>refining

I’ve always gotten a good yield from this.
Just having trouble wrapping my head around why the magnetics need to be removed before washing

 

[orvi]

So i have those Ic chips that came off of the ram sticks. These chips (forgive me because I don't know the actual nes for these) so I have no real base metals to worry about. I have already washed them I'm hot HCl 3 times, then rinsed with water until my rinses were pretty clear. So which process do I need to do? Pyrolyzation or incineration? I tried to just burn a pan of them with a torch.
It let off far too much smoke of nasty smell. So what are my options at this point? Because I have quite a bit of them. About 900. Grams

That is the thing. Any half-baked open air burning is incomplete. You need to do this in furnance, where you can maintain at least 700-800°C to maintain steady and complete burning. This was discussed so many times... Dig it up here on the forum, kurtak has a lot of experience with this.
In electric furnance you don´t have nice flow of air, so if you put chips inside, you will effectively create smoking bomb
Thing is, if you have plenty of oxygen, long retention time in furnance and high temperature inside = good insulation of the furnance- you can take practically any organic material and burn it that completely, that no particle of unburnt harmful carbon residue will escape.
Don´t use torch, but heat gun. One that can go up to 600°C or better more. And has temperature regulation, so when burning kicks in, you can lower the temperature to catch the air influx sufficient to burn completely. And avoid melting of the ashes, as carbon can get insanely hot.

 

[snoman701]

Actually, a proper incineration is to heat to 450 degrees C in a reducing environment effectively pyrolizing all of the volatile ingredients, then 650 degrees C in an oxidizing environment. You do not want to go above the melting temperature of aluminum.

The smoke from the 450 degree pyrolisis is to be fed into an appropriate afterburner to fully oxidize the volatile agents.

 

[kurtak]

Things I have posted about proper incineration

https://goldrefiningforum.com/threa...s-from-carbon-and-organics.28551/#post-301413
https://goldrefiningforum.com/threads/what-about-beryllium-in-ic-chips.27671/page-2#post-301617
And this is a good "general info" thread about pyro (incineration/smelting) processes for e-scrap

Edit; - Opps - forgot to post the link

https://goldrefiningforum.com/threads/pyrolysis-reactor.22581/
Kurt

 

[Yggdrasil]

Things I have posted about proper incineration

https://goldrefiningforum.com/threa...s-from-carbon-and-organics.28551/#post-301413
https://goldrefiningforum.com/threads/what-about-beryllium-in-ic-chips.27671/page-2#post-301617
And this is a good "general info" thread about pyro (incineration/smelting) processes for e-scrap

Edit; - Opps - forgot to post the link

https://goldrefiningforum.com/threads/pyrolysis-reactor.22581/
Kurt

Excellent, these deserves being read again, a lot of good information in here.

 

[kurtak]

You do not want to go above the melting temperature of aluminum.

Based on my experience - going above the melt temp of aluminum is actually not a concern (during pyrolizing/incineration)

Why ?

because the aluminum that is in some IC chips is usually the heat spreader that the underside of the silicon die sits on (if they are aluminum bond wires it doesn't matter anyway)

the gold bond wires come into & attach to the top side of the die

so there is a thin layer of epoxy between the bond wires & the heat spreader

when the epoxy turns to carbon it leave a thin carbon insulation layer between the bond wires & aluminum heat spreader

Because of the huge difference in the melt temp between aluminum & gold - when the aluminum gets molten the carbon at the bottom of the chip will crack allowing the aluminum to ooze out the bottom of the chip leaving the bond wires embedded in the carbon layer between the heat spreader & the bond wires

At least that has been my experience & having run several tests to see if that held true

I can post those test results - if need be --- (& time allows - if you ask)

Kurt

 

[kurtak]

Can you please clear up why we need to remove the magnetic materials before washing/rinsing off the carbon after milking?

First of all - per the bold print - I assume you mean milling & not milking

That said - anytime you are washing material to concentrate the values (in this case gold bonding wires) you want the size of the material to be relatively "uniform" in size

Why ?

Because in the washing process - lager material will cause a turbulence in the wash water & that turbulence will cause smaller material to lift & wash over the top of what is collecting/loading in your concentrator device (whether it be a sluice box, blue bowl, gold pan or fine gold concentration table)

Example; - say you are running a 4 or 6 inch gold dredge - once the riffles in the sluice box becomes loaded with larger rocks - the turbulence caused by those larger rocks is going to start to cause smaller/finer gold to lift & wash over the top of the material loaded in the riffles

That does not mean that you won't also collect smaller/finer gold in the sluice box - because you most certainly will --- it only means that once the riffles are loaded with larger rocks - the turbulence caused by the larger rocks start lifting some of the smaller/finer gold washing some of that gold out the sluice box

Like wise - the Kovar wires & or heat spreaders - which are much larger then the bond wires - will cause this same kind of turbulence in your concentrator device & though you will certainly collect bond wires - some will most certainly lift & washout

So you need to remove those lager Kovar wires/heat spreaders with sifting &/or magnet before running your milled carbon/ash through your concentrator device --- if you don't - though you will collect bond wires - gold will most certainly be lost

Even with relatively uniform material size you can wash gold away if - (1) water flow is not adjusted according to material size &/or (2) the rate at which you feed the material to the device is not done right --- & that is a discussion all it's own

AND - for what it is worth - IMO - a blue bowl is one of the worst devices you can use for concentrating chip ash/carbon - worse than that is using a piece of ribbed drain pipe

Kurt

 

[Shark]

AND - for what it is worth - IMO - a blue bowl is one of the worst devices you can use for concentrating chip ash/carbon - worse than that is using a piece of ribbed drain pipe

I agree, been through that disaster before.