Processing Iron Wires from inside of IC chips

[Tzoax]

After 8 months of processing IC chips, flatpacks and BGA chips, I collected certain amount of iron wires from inside of chips on the following way:
1. I mechanically striped all wires from the edges of chips with scalpel
2. Incineration of the chips
3. Shaking in the jar and pass through the sieve
4. I repeat 2. and 3. until all of the chips becomes incinerated and then passing through the sieve once again the whole powder
5. Rinsing with water until color becomes clear
6. Then I leave couple of inches of water in the jar and I remove the iron wires with magnet through water and that is the way how I get the wires
7. I dried the wires and weight them, they have 195 grams. Here is the picture:

So, I looked trough the microscope and I saw a plenty of golden wires. I was thinking to mechanically separate it since the gold is heavier than iron, and it worked partially. When I shake a bit and collect the wires with magnet this it what was left on the bottom:

The pure golden wires. I thought that it is the most of the gold but when I looked through the microscope again there are still a plenty of golden wires and it seems that some of the iron wires are plated with gold.
Now it was clear to me that this must be done chemically. Now I did one more step:
I took the magnet again (this time when the wires was dried) and I removed iron wires. This time I had a residue that was about 5 percents of total weight. There was golden wires with some of copper wires. That concentrate is familiar to me and I will process it with diluted nitric and AR. The problem was that 95% of total weight of iron wires with a lot of golden wires trapped there.
I decided to boil the iron wires with HCl(10%).


I was surprised with the green color of solution, I thought it would be brown like rust. After 4 hours of boiling I had to stop because I was in a hurry. So I planned to filter solution, wash with water and save it to continue boiling next time. Here is the picture of what was left in the filter. I think it is a rust (iron oxide).

And here is the remaining solution of HCl plus it was about 50% dilluted because I mixed it with water that was used for cleaning the rest of wires. Next time I will use fresh HCl since this was dilluted and this color is a strange to me since there is a lot of iron and maybe a little of copper. Maybe it is because of nickel...
...I will continue in the next post since the 5 images per post is maximum...

 

[Tzoax]

And then two things happened that I cannot explain...

1. When I looked again with microscope instead of golden wires I saw the same wires that should be golden but they was shiny white, like silver, like it was plated with something(most probably iron). And then, after half of hour when I looked again, they were rusted. the golden wires was plated with iron then rusted. it was new experience to me and that is my first thing to learn about.

2. The remaining green solution that was in the bottle started to sediment yellow substance. I thing it is rust but I am not sure. Here is the picture:


And one more thing I noticed. In the remaining wires there are two layers. It looks like concentrate, but maybe it is just a rust that was too deep to clear with water since the wires are tight and hardened. Here is the picture:


I am planning to continue HCl boiling until all iron is dissolved. Any help is welcome, thank You.

 

[kurtak]

Tzoax

yes - gold wires do & well "drag" out along with magnetic wire

The magnetic legs in IC chips are kovar = iron/nickel/cobalt alloy (some C/Si/Mn) nickel 29% cobalt 17%

I use 31.45% HCl on a low boil (simmer boil) & I only add a little water to allow for evaporation - watch glass on top of beaker to minimize evaporation

1pound magnetic legs - I start with about 2000 - 2250 ml of 31.45% HCl plus 200 - 250 ml water in a 4000 ml beaker

It takes about 24 hours (or a bit more) for this first treatment to dissolve as much Fe/Ni/Co as it can

Let cool - decant --- you will likely have Fe/Ni/Co chloride crystals in the bottom of beaker along with some un-dissolved kovar & ash (&/or carbon if not completely incinerated to pure ash) & bits of broken silicon from the silicon chips

Second HCl treatment - add about 500 - 600 ml HCl (31.45%) & about 100 ml water - simmer boil till there is absolutely no more reaction (I usually just leave it on the hot plate another 24 hours

Decant - filter/wash out as much acid as possible - incinerate to burn off trace HCl & burn any possible carbon to ash

You should have some silver &/or Ag/Pd foils in this as the kovar is plated with Ag &/or Ag/Pd - as is shown in the picture (its an Ag/Pd alloy plating)

So - treat this with a nitric treatment to dissolve the Ag &/or Ag/Pd - filter/wash "good" again & cement your Ag & Pd out & add to silver going to the silver cell

You can then go for the gold

Kurt

Edit to ad --- the more dilute the HCl the longer it is going to take even with a boil - 10% HCl may take a couple days --- I believe Geo puts his through AP prossess

 

[Tzoax]

Thank You very much Kurt. You helped me a lot.
This is my first time processing wires from chips, and I had no idea that there was Ag or Pd. Thanks again, great advices and informations.

I mixed the hot water with the wires and rinsed many times, all of the bottom layer was rinsed and now there are mostly wires.
I looked through the microscope and there are still kind of rust on golden wires. I will continue the boiling in HCl and see what happens.
I was in doubt will I use HCl boiling or AP and I choose HCl boiling since it is much faster and there are less risk of dissolving some of the values.

 

[GotTheBug]

Would it be more efficient to run the magnetics through a sulfuric cell?

 

[Tzoax]

I don't know about sulphuric cell, I have no experience with wires from chips at all, but sure it is faster that way.
I am boiling 8 hours for now on in 10% HCl and only 1/3 of wires dissolved. On the other hand, mixed pins from motherboards and PCI cards that I put in AP dissolved after 7 days. So maybe the AP is better solution since You have to do nothing and it takes some time, but after one week is over. But, I don't know would it take some other issues since I haven't try with specific wires from chips. They are far more magnetic than regular pins I dissolved in AP. So I'm not sure about time that it takes to dissolve in AP compared to the mixed pins.

 

[MarcoP]

In my head I always thought to put them in the stock pot but I will follow this thread with care as I always been curious on how to treat magnetic material.

 

[solar_plasma]

Also, it would be nice to have an idea of yield numbers. Once I dissolved a hand full of those wires and didn't find anything precious in it...probably because I was way too much more a beginner in refining than today. Dissolving kovar takes a lot of acid and time, so I wonder, if it is worth any greater effort...

 

[Tzoax]

In a meanwhile I processed the concentrate from the beginning of process that I separated (those 5% of non-magnetic material) with 50/50 nitric acid and distiled water. It is ready for AR.

I will wait until I finish the iron wires that are boiling in HCl and then I will mix it together, process with AR, and that way I will have some idea of yield numbers. At the beginning I had 195 grams of iron wires, and I will see how much gold will be there.
***Against confusion - I saw what Kurt was saying and according to the picture he posted that he was processing all of the magnetic parts from chips including plates. There are only wires in this process . The other parts from chips - wires, plates and silicon chips that I removed before water rinsing I keep in a separate jar. These iron wires "survived" 2 times of sieving and then they was collected from water with magnet. So i looked and even there I saw a golden wires but not as much like here, and there would be some more of the values, like Ag and Pd. There are much more weight there, and I am considering to process it with AP and collect the results.

 

[patnor1011]

Also, it would be nice to have an idea of yield numbers. Once I dissolved a hand full of those wires and didn't find anything precious in it...probably because I was way too much more a beginner in refining than today. Dissolving kovar takes a lot of acid and time, so I wonder, if it is worth any greater effort...

There is nothing "in" them. Amount of gold on these pins goes down to incineration and grinding. If done properly not much of gold can survive to stay attached to tip of a pin. I do not say you can remove everything but when done properly, amount of gold left on tip - rather bits of gold solder do not warrant heavy use of chemicals, recovered gold is not going to cover cost associated with doing that.
I have mentioned it several times, I use simplest method possible. I toss them in bucket of sea water or just water with handful of salt and splash of HCl (like 50ml). It take time but they will rust away eventually. I am down to about 40% of my initial-first batch and it did not cost me anything. I occasionally swirl water around, break lumps with rod. Pour off rusty water and top up with fresh one.

 

[Tzoax]

The sea water or salt with a little HCl is a great idea, and it is definitely the cheapest method with at least work. Thank You Patnor for great information. The only consequence is that process will be done after several months. After this tests I am doing and getting familiar with the results I will surely keep the wires in a sea water+HCl while I collect them. They will slowly dissolve and at any time if I ever have a reason to speed up process I could process them in AP or boiling HCl. It can only benefit.

The golden wires will always get tangled with other wires and other materials more or less. At first, when I started processing chips I was throwing away that iron wires, plates and the rest. My results was like this:

And when I get some practice I am getting about 2 grams of gold per kilogram of mixed chips, like this for example:

Now I learned there are even more gold inside of those residues like wires and plates. That is why I am trying to find out how much of gold is there to keep an eye on some approximately values. I am very satisfied with my results even without that, but I would gladly like to improve my results and include that values to my table.

 

[Geo]

Use fine iron bits to cement copper from old or spent AP solution. Any gold will be left unaffected in the copper which will be parted in it's own cell.

 

[FrugalRefiner]

Like Pat, I have more time than money to spend on chemicals. I am a fan of frugal refining. 8)

Dave

 

[g_axelsson]

And I'm a fan of FrugalRefiner. 8)

Göran

 

[Tzoax]

Use fine iron bits to cement copper from old or spent AP solution. Any gold will be left unaffected in the copper which will be parted in it's own cell.

Thank You very much Geo, I am planning to make my first AP tank bubbler soon. So far I've learn to refine gold from fingers, ceramic processors and chips, I was selling the rest of boards with pins on it because the methods I've used was not paying off. And now I am learning about AP process. I watched all of your videos, and I learned a lot from You. Actually, the first time I found out that chips have gold inside of them was on one of Your videos where You were explaining that most of the value in RAM modules was inside of chips. Thank You very much Geo for all the great advices and tutorials You shared.

 

[Tzoax]

Is there anything more frugal than Acid peroxide with bubbler?

 

[FrugalRefiner]

Is there anything more frugal than Acid peroxide with bubbler?

It depends on the material you're refining. For fingers, AP is hard to beat because there's not much base metal to deal with and the AP is reusable.

For plated material, a stripping cell is often the best alternative because you don't waste acid dissolving base metals, electricity is cheap, and the sulfuric acid is reusable.

For iron based material, I like Pat's method.

For ICs, pyrolization, incineration, and panning are inexpensive, especially if you can use fallen tree branches as the fuel.

Different methods work best for different materials.

Dave

 

[Tzoax]

Is there anything more frugal than Acid peroxide with bubbler?

It depends on the material you're refining. For fingers, AP is hard to beat because there's not much base metal to deal with and the AP is reusable.

For plated material, a stripping cell is often the best alternative because you don't waste acid dissolving base metals, electricity is cheap, and the sulfuric acid is reusable.

For iron based material, I like Pat's method.

For ICs, pyrolization, incineration, and panning are inexpensive, especially if you can use fallen tree branches as the fuel.

Different methods work best for different materials.

Dave

Thank You very much Dave. I was avoiding using sulphuric stripping cell since AP method looks better for my conditions. I tested some pins with AP with 10% HCl and 3% H2O2 and it tooks 5 days to completely dissolve base metals and leave only gold foils, and that was without air pump. Now I am considering to make a small AP tank (5 liters) with air pump and test again with non-magnetic (barely magnetic) pins, and calculate values. If it is paying off I will continue using AP. After spent AP solution I will drop copper like Geo said.

 

[FrugalRefiner]

Thank You very much Dave. I was avoiding using sulphuric stripping cell since AP method looks better for my conditions. I tested some pins with AP with 10% HCl and 3% H2O2 and it tooks 5 days to completely dissolve base metals and leave only gold foils, and that was without air pump. Now I am considering to make a small AP tank (5 liters) with air pump and test again with non-magnetic (barely magnetic) pins, and calculate values. If it is paying off I will continue using AP. After spent AP solution I will drop copper like Geo said.

Everyone's situation is different and there are many ways to skin the cat. Many people prefer AP for small pins, and it's a perfectly good method. HCl is still relatively cheap and readily available for most of us. Once the AP is started and it becomes a CuCl₂ leach, it can be reused for quite some time before other base metals build up in it.

Pins that are barely magnetic are likely a copper based alloy with a nickel plating followed by the gold plating. It's the nickel that is attracted to the magnet. They should do well in AP.

Dave

 

[Tzoax]

Thank You very much Dave. I was avoiding using sulphuric stripping cell since AP method looks better for my conditions. I tested some pins with AP with 10% HCl and 3% H2O2 and it tooks 5 days to completely dissolve base metals and leave only gold foils, and that was without air pump. Now I am considering to make a small AP tank (5 liters) with air pump and test again with non-magnetic (barely magnetic) pins, and calculate values. If it is paying off I will continue using AP. After spent AP solution I will drop copper like Geo said.

Everyone's situation is different and there are many ways to skin the cat. Many people prefer AP for small pins, and it's a perfectly good method. HCl is still relatively cheap and readily available for most of us. Once the AP is started and it becomes a CuCl₂ leach, it can be reused for quite some time before other base metals build up in it.

Pins that are barely magnetic are likely a copper based alloy with a nickel plating followed by the gold plating. It's the nickel that is attracted to the magnet. They should do well in AP.

Dave

Thanks Dave, I also tested the green mask with gold plating from BGA chips, RAM boards with gold traces and pieces of other green masks with gold traces and it worked very well in AP.
The only "problems" that occurs was:
1. white powder which I believe will not be problem, the boiling in water and filtering will remove Pb, and I will boil in HCl to remove if any of base metals remains. And then incineration and nitric for collecting silver.
2. Many of little pieces of green mask is floating. I believe that it will be solved by incineration.

I have some cards (mainly audio cards) that are all gold plated underneath the green mask. I was searching and wound that boiling in lye (NaOH) will remove it. so that will be my next test in AP, i believe that cards and motherboards that are whole gold plated yields a lot.