Accomplished nothing so far

[Edwin Price]

Hello all. I was a much better engineer than I am a gold recovery chemist. I have disassembled a workstation, two laptops, a cell phone and multiple other electronics and recovered absolutely nothing so far. I have used aqua regia on computer parts after breaking them down in nitric or hydrochloric acid or even cleaning with lye. After washing the parts with water and heating in aqua regia, I get what appears as a yellow or green liquid. The solution tests weakly for gold (light purple from stanneous chloride). After killing nitric with urea, I've added sodium metabisulfite, which the solution gobbles up, but never produces any tangible precipitate. On two occasions I've gotten violent overflows. But nothing really ever drops from the solution. Any suggestions as to what I'm doing wrong would be much appreciated. Thank you.

 

[anachronism]

Doesn't sound like you're doing anything wrong Edwin. I think the problem lies in the scale of what you're doing. You're getting the right results but you don't have enough raw product to get a visible amount of physical gold, if what you're saying here is accurate. From a weak purple test you might get a light dusting (volume dependent) and that's about it.

Nailing the processes is good, now you need to get plenty more gold into the solution. Edit: My post assumes that you are testing negative after adding SMB. If not then you haven't denoxxed and Sulphamic Acid is much better at doing this than Urea.

 

[Yggdrasil]

Hello all. I was a much better engineer than I am a gold recovery chemist. I have disassembled a workstation, two laptops, a cell phone and multiple other electronics and recovered absolutely nothing so far. I have used aqua regia on computer parts after breaking them down in nitric or hydrochloric acid or even cleaning with lye. After washing the parts with water and heating in aqua regia, I get what appears as a yellow or green liquid. The solution tests weakly for gold (light purple from stanneous chloride). After killing nitric with urea, I've added sodium metabisulfite, which the solution gobbles up, but never produces any tangible precipitate. On two occasions I've gotten violent overflows. But nothing really ever drops from the solution. Any suggestions as to what I'm doing wrong would be much appreciated. Thank you.

Welcome.
We will help you solve this.

As Jon says you may have too little in the solution and you may not have denoxed enough.
I consider the use of Urea not desirable for two reasons it do not convert the nitrates and it may
under certain conditions create an explosive compound.

Another thing that is not good is that you apparently has leached whole boards,
this leaves undissolved base metal that the dissolved Gold may cement out on.
Particularly bad if it happens inside the traces.

But we still prefer you to study these links in the mean time.
Recommended first is Safety then Waste treatment all this while reading Hokes book.
You as an Engineer should be used to studies right

We ask our new members to do 3 things.
1. Read C.M. Hokes book on refining jewelers scrap, it gives an easy introduction to the most important chemistry regarding refining.
It is free here on the forum: https://goldrefiningforum.com/phpBB3/viewtopic.php?f=54&t=19798
2. Then read the safety section of the forum: https://goldrefiningforum.com/forums/safety.47/
3. And then read about "Dealing with waste" in the forum: https://goldrefiningforum.com/threads/dealing-with-waste.10539/

Suggested reading:
https://goldrefiningforum.com/forums/the-library.101/
https://goldrefiningforum.com/threads/when-in-doubt-cement-it-out.30236/
https://goldrefiningforum.com/threa...le-read-this-before-you-post-about-ore.33333/


Forum rules is here.
https://goldrefiningforum.com/threads/gold-refining-forum-rules.31182/

 

[Martijn]

Hello all. I was a much better engineer than I am a gold recovery chemist. I have disassembled a workstation, two laptops, a cell phone and multiple other electronics and recovered absolutely nothing so far. I have used aqua regia on computer parts after breaking them down in nitric or hydrochloric acid or even cleaning with lye. After washing the parts with water and heating in aqua regia, I get what appears as a yellow or green liquid. The solution tests weakly for gold (light purple from stanneous chloride). After killing nitric with urea, I've added sodium metabisulfite, which the solution gobbles up, but never produces any tangible precipitate. On two occasions I've gotten violent overflows. But nothing really ever drops from the solution. Any suggestions as to what I'm doing wrong would be much appreciated. Thank you.

Welcome to the forum Edwin.

A lot to ask and suggest to you before you should proceed. So put things on hold for now and let us review please.

Can you tell us about your workspace? fume hood, lab glass, PPE, etc.
You will receive links to mandatory literature @Yggdrasil
Did you go after visible gold from e-waste parts only or also for, e.g. bonding wires in chips?
Did you leach or clean anything in both HCL and HNO3 after each other?
Did you dissolve any PCB's holding gold in AR?
How do you make AR?
Yellow solution can be gold, but can also be iron. Green is usually copper with other base metals.
A much made mistake is premixing aqua regia (AR) and ending up with a solution that will redissolve any gold that was precipitated out.
one ml of 68% HNO3 added to HCL can dissolve 1 gram of gold.
so depending on how much gold you dissolved, you probably have way to much nitric in there.
Urea only deNOx-es NOx from solution, it does not remove free excessive HNO3 from solution.
Light purple stannous test result indicates very little gold as said.> put of this solution some aside in a dropper bottle to have a reference testing solution to test if your stannous chloride still works good. (you will have moments of doubt and this will tell.)

The completeness of your answers will help speed things up in terms of providing the best guidance.

Martijn.

 

[Edwin Price]

Welcome to the forum Edwin.

A lot to ask and suggest to you before you should proceed. So put things on hold for now and let us review please.

Can you tell us about your workspace? fume hood, lab glass, PPE, etc.
You will receive links to mandatory literature @Yggdrasil
Did you go after visible gold from e-waste parts only or also for, e.g. bonding wires in chips?
Did you leach or clean anything in both HCL and HNO3 after each other?
Did you dissolve any PCB's holding gold in AR?
How do you make AR?
Yellow solution can be gold, but can also be iron. Green is usually copper with other base metals.
A much made mistake is premixing aqua regia (AR) and ending up with a solution that will redissolve any gold that was precipitated out.
one ml of 68% HNO3 added to HCL can dissolve 1 gram of gold.
so depending on how much gold you dissolved, you probably have way to much nitric in there.
Urea only deNOx-es NOx from solution, it does not remove free excessive HNO3 from solution.
Light purple stannous test result indicates very little gold as said.> put of this solution some aside in a dropper bottle to have a reference testing solution to test if your stannous chloride still works good. (you will have moments of doubt and this will tell.)

The completeness of your answers will help speed things up in terms of providing the best guidance.

Martijn.

Can you tell us about your workspace? fume hood, lab glass, PPE, etc.
Answer: Outdoors covered work area. Use large fan to direct any fumes skyward. Standard Pyrex, borosilicate lab glassware. Hot plate, Mapp gas torch, standard crucibles, etc. Use safety glasses, chemical resistant gloves and cloth mask (if needed).

You will receive links to mandatory literature @Yggdrasil - check
Did you go after visible gold from e-waste parts only or also for, e.g. bonding wires in chips? Answer: mostly visible
Did you leach or clean anything in both HCL and HNO3 after each other? Answer: not 100% certain
Did you dissolve any PCB's holding gold in AR? Answer: Yes (parts).
How do you make AR? Mix three parts Muriatic acid and one part Nitric.

 

[Yggdrasil]

Can you tell us about your workspace? fume hood, lab glass, PPE, etc.
Answer: Outdoors covered work area. Use large fan to direct any fumes skyward. Standard Pyrex, borosilicate lab glassware. Hot plate, Mapp gas torch, standard crucibles, etc. Use safety glasses, chemical resistant gloves and cloth mask (if needed).

You will receive links to mandatory literature @Yggdrasil - check
Did you go after visible gold from e-waste parts only or also for, e.g. bonding wires in chips? Answer: mostly visible
Did you leach or clean anything in both HCL and HNO3 after each other? Answer: not 100% certain
Did you dissolve any PCB's holding gold in AR? Answer: Yes (parts).
How do you make AR? Mix three parts Muriatic acid and one part Nitric.

Your description of your process confuses me.
So please can you explain in detail what you have done?
1. You broke down the computers into pieces.
2.???

Did you sort out the different material?
What did you do with the CPU, the ram sticks, the Motherboards etc. ?



Just a short clarification:
1. We never dissolve the Gold until it is separated from the PCB as foils or otherwise separated from any base metal.
2. Recommended AR in this forum is: Add HCl enough to cover the material
and then add small increments of Nitric until we have accomplished the task.
3. When ever AR is used we may need to deNOx it , meaning decompose the extra Nitric Nitrates and NOx.
For this we use Sulfamic acid or better do not use too much Nitric.


Most/much of the Gold are in the Chips and not visible.
This needs a special processing to liberate/recover.

Edit to adjust text

 

[andu]

Usually, unless you plan on dealing with each and single metal in there, you pick the nice chips as fast as possible and sell the board, you still need a good bunch of them, kilos, and each chip tend to be as heavy as 7-15g on average, without heatsinks.

I like tin .

 

[Martijn]

Can you tell us about your workspace? fume hood, lab glass, PPE, etc.
Answer: Outdoors covered work area. Use large fan to direct any fumes skyward. Standard Pyrex, borosilicate lab glassware. Hot plate, Mapp gas torch, standard crucibles, etc. Use safety glasses, chemical resistant gloves and cloth mask (if needed).

Sounds good enough if you keep the fumes down. The fan can corrode if not resistant to the fumes.

Did you go after visible gold from e-waste parts only or also for, e.g. bonding wires in chips? Answer: mostly visible

You need to learn more about recovery processes. Lots of info here Search for the AP process.

Did you leach or clean anything in both HCL and HNO3 after each other? Answer: not 100% certain

If there was some of one acid left from a first leach, the second will create some weak AR and dissolve some gold. Check the solutions with stannous.

Did you dissolve any PCB's holding gold in AR? Answer: Yes (parts).

There will be some gold chloride inside the fiber board layers. Hard to get out.

How do you make AR? Mix three parts Muriatic acid and one part Nitric.

What yggdrasil said.

 

[Martijn]

Can you tell us about your workspace? fume hood, lab glass, PPE, etc.
Answer: Outdoors covered work area. Use large fan to direct any fumes skyward. Standard Pyrex, borosilicate lab glassware. Hot plate, Mapp gas torch, standard crucibles, etc. Use safety glasses, chemical resistant gloves and cloth mask (if needed).

You will receive links to mandatory literature @Yggdrasil - check
Did you go after visible gold from e-waste parts only or also for, e.g. bonding wires in chips? Answer: mostly visible
Did you leach or clean anything in both HCL and HNO3 after each other? Answer: not 100% certain
Did you dissolve any PCB's holding gold in AR? Answer: Yes (parts).
How do you make AR? Mix three parts Muriatic acid and one part Nitric.

This can help sorting the goodies from the scrap:
https://goldrefiningforum.com/threads/list-of-items-that-contain-precious-metals.22304/

 

[Edwin Price]

Your description of your process confuses me.
So please can you explain in detail what you have done?
1. You broke down the computers into pieces.
2.???

Did you sort out the different material?
What did you do with the CPU, the ram sticks, the Motherboards etc. ?



Just a short clarification:
1. We never dissolve the Gold until it is separated from the PCB as foils or otherwise separated from any base metal.
2. Recommended AR in this forum is: Add HCl enough to cover the material
and then add small increments of Nitric until we have accomplished the task.
3. When ever AR is used we may need to deNOx it , meaning decompose the extra Nitric Nitrates and NOx.
For this we use Sulfamic acid or better do not use too much Nitric.


Most/much of the Gold are in the Chips and not visible.
This needs a special processing to liberate/recover.

Edit to adjust text

 

[Edwin Price]

I did some research prior to my first attempts to retrieve gold for electrical and computer parts. Many of the internet or YouTube instructional videos are incomplete and obviously omit steps and details. Initially, I retrieved several laptops, pc work stations, monitors, routers, modems, cell phones and even boxes of electrical parts. I systematically disassembled and removed what was considered gold bearing components. I re-assembled the computers, monitors, etc. with the non-useful parts inside and took them back to the local dump electronics disposal section. I cut the boards containing gold bearing components into small parts that would fit in a 1000ml beaker. At first I tried removing the gold into solution with full strength AR by boiling followed by filtering. However, after killing the Nitric with urea. The solution gobbled up a ton of SMB, but resulted in no usuable participate. Next attempt I bathed a new set of small gold bearing components in Sodium Hydroxide to remove solder covering. Repeated the process, but again got no substantial precipitation. Although something in the solution gobbled up another ton of SMB, even to the point of a violent spewing reaction. All I ended up with was beautiful clear yellow/gold or green solutions that tested for very low to no gold content. Treating the waste products in hydrochloric or nitric and boiling produced soluble black messes. Drying and torching with MAPP gas in crucible with sodium carbonate and sprinkling with borax, produced no gold whatsover. I also tried cleaning and boiling leftover waste products, solutions, filters, etc. with fresh acids. The dried residue, whether black, brown, white or tan contained no detectable gold. I believe it is mostly copper, lead, silver or SMB remains. Obviously, there is some, at least minimal amount of gold, in this waste product so far. But, I have no clue how to isolate and retrieve it at this point. Henceforth, I will drastically cut back on the amout of nitric acid used in the process and I have ordered sulphalmic acid. Thank you for the help provided so far. Regards, Edwin Price Jr., PE

 

[Yggdrasil]

I'll comment in bold inside the quote:

I did some research prior to my first attempts to retrieve gold for electrical and computer parts.
Many of the internet or YouTube instructional videos are incomplete and obviously omit steps and details.
Completely true and the reason we do not endorse videos in general and Youtube in particular for learning.
Initially, I retrieved several laptops, pc work stations, monitors, routers, modems, cell phones and even boxes of electrical parts.
I systematically disassembled and removed what was considered gold bearing components. Good, but did you collect the chips and memory too?
I re-assembled the computers, monitors, etc. with the non-useful parts inside and took them back to the local dump electronics disposal section.
I cut the boards containing gold bearing components into small parts that would fit in a 1000ml beaker.
No reason to do this, we dissolve the underlying substrate of Nickel and Copper to release the foils.
This is usually done with a Cupric Chloride etch. AKA AP method, it can also be done with Nitric.
At first I tried removing the gold into solution with full strength AR by boiling followed by filtering.
As I say we "never" dissolve the whole pieces of PCB in AR or other solutions dissolving the Gold,
the dissolved Gold will cement out inside the PCBs and some of the pregnant solution will be bound up inside the PCB.
However, after killing the Nitric with urea. Not Good
The solution gobbled up a ton of SMB, but resulted in no usuable participate. The reason is that as fast as the Gold precipitates it is re-dissolved in the still active AR.
Next attempt I bathed a new set of small gold bearing components in Sodium Hydroxide to remove solder covering.
Repeated the process, but again got no substantial precipitation. Same reason as before, you have changed nothing.
Although something in the solution gobbled up another ton of SMB, even to the point of a violent spewing reaction.
All I ended up with was beautiful clear yellow/gold or green solutions that tested for very low to no gold content. Was there any black powder in the bottom?
Treating the waste products in hydrochloric or nitric and boiling produced soluble black messes.
Drying and torching with MAPP gas in crucible with sodium carbonate and sprinkling with borax, produced no gold whatsover. Why should it?
I also tried cleaning and boiling leftover waste products, solutions, filters, etc. with fresh acids.
The dried residue, whether black, brown, white or tan contained no detectable gold.
I believe it is mostly copper, lead, silver or SMB remains.
Obviously, there is some, at least minimal amount of gold, in this waste product so far.
But, I have no clue how to isolate and retrieve it at this point.
Henceforth, I will drastically cut back on the amout of nitric acid used in the process and I have ordered sulphalmic acid.
Thank you for the help provided so far. Regards, Edwin Price Jr., PE

How much material did you have and do you have pictures of it?
And please put your stuff away and read the material we gave to you.
When you feel ready, formulate a step by step plan with what you expect of reactions.
And we can comment and adjust it for you.

 

[Edwin Price]

I appreciate the responses. But, why was the urea totally ineffective? Before addition, the hot AR reacted on copper by forming a green residue. But when I tested the de-noxed solution on copper tubing there was no effect. Wouldn't that indicate the acid was neutralized?

I also did the requested reading. TBH most of it seems quite dated and overly detailed. I am only interested in gold recovery, not silver, palladium, platinum, copper, etc. I have switched from urea to sulphamic acid (just received) and will greatly reduce the amount of nitric acid used. Do you all have some type procedure specifically for gold retrieval from computer and electronic parts with steps that detail (1) limits and precautions, (2) equipment and chemicals required, (3) a step by step process that covers preparation of gold bearing parts, addition of chemicals including quantities, timing, heating, testing, filtering, de-noxing, precipitation, washing/drying gold powder, smelting and recovering gold beads/button? If not, given the necessary knowledge, as a registered professional nuclear engineer with decades of naval and commercial experience, perhaps I could help write one. Thank you, edp

 

[Edwin Price]

Pics of useless solutions…

 

[Yggdrasil]

I appreciate the responses.
But, why was the urea totally ineffective?
Because the Urea only converts the remaining Nitric into Urea Nitrate, it do nothing with the other Nitrates or NOx in the solution.
Before addition, the hot AR reacted on copper by forming a green residue. AR will dissolve Copper, not make a green residue.
But when I tested the de-noxed solution on copper tubing there was no effect.
Do you know for sure? There may have been so little Gold you can not see it. The solution only need to be acidic to cemento out Gold or other PMs
Wouldn't that indicate the acid was neutralized? It certainly indicates that the solution is depleted, did you measure pH?
We differentiate between depleted , neutralized and deNOxed.
Depleted is self evident, one of the substances that is active has run out.
Neutralized mean in chemical terms that the pH has reached 7, it is neither acidic or basic.
DeNOxed means all the products from the Nitric, as the Nitrates, the Nitric itself and the NOx has been destroyed/converted.

I also did the requested reading. Most needs months for this
TBH most of it seems quite dated and overly detailed. If you are referring to Hokes book, yes it is overly detailed and dated,
but the chemistry is the same and its purpose its to teach you the basic chemistry behind refining precious metals.
I am only interested in gold recovery, not silver, palladium, platinum, copper, etc.
As said, the chemistry needed to extract and refine them are similar except for Silver.
I have switched from urea to sulphamic acid (just received) and will greatly reduce the amount of nitric acid used.
Sulfamic acid needs to used differently than Urea, the solution need to be close tto boiling and you need to have plenty of head room in the beaker.
Do you all have some type procedure specifically for gold retrieval from computer and electronic parts with steps that detail (1) limits and precautions, (2) equipment and chemicals required, (3) a step by step process that covers preparation of gold bearing parts, addition of chemicals including quantities, timing, heating, testing, filtering, de-noxing, precipitation, washing/drying gold powder, smelting and recovering gold beads/button?
Many do, but this is something we ask from new guys that has made a mess or done mistakes, it makes it easier to see where things will/can go wrong.
If not, given the necessary knowledge, as a registered professional nuclear engineer with decades of naval and commercial experience, perhaps I could help write one. Thank you, edp

Commenting in Bold again.

We prepare the material by cutting of all Gold contact pads from memory, add on cards and such as close to the Gold as possible.
(Gold plated boards do not have much Gold on them as the plating is exeedingly thin, so we usually do not bother with them)
This limits the amount of Tin (Which will/can create a big mess later) and size of the batch.
This are then treated to release the foils/pads from the cards.
These foils are then dissolved and refined.

How much material did you treat in each batch?
There is a real chance you had too little Gold to even notice it.
The picture I asked for was not your solution, but your raw material.
Do not throw anything away, it is almost the only way you can loose your Gold.

Other parts are separated and processed in a different way.

 

[Yggdrasil]

Pics of useless solutions…

Please pictures of you "raw" material, your solution is less interesting, not much info for us there.
But do not throw it away.

 

[Edwin Price]

Commenting in Bold again.

We prepare the material by cutting of all Gold contact pads from memory, add on cards and such as close to the Gold as possible.
(Gold plated boards do not have much Gold on them as the plating is exeedingly thin, so we usually do not bother with them)
This limits the amount of Tin (Which will/can create a big mess later) and size of the batch.
This are then treated to release the foils/pads from the cards.
These foils are then dissolved and refined.

How much material did you treat in each batch?
There is a real chance you had too little Gold to even notice it.
The picture I asked for was not your solution, but your raw material.
Do not throw anything away, it is almost the only way you can loose your Gold.

Other parts are separated and processed in a different way.

Again, thank you for the valuable info in your respones. It appears obvious to me now that I contaminated the initial batches with excess copper, tin, lead, etc. by not just consolidating the gold plated parts. I appreciate you for pointing out that fact. However, I believe that I did have some significant gold in the mixture. On my first attempt a couple months ago, I used a mixture of 45% acetic acid, 30% H2O2 and salt plus heat and an air bubbler to remove gold plating. Flakes of gold definitely came off and fell to the bottom of the beaker. Perhaps I should have just accumulated these flakes for a while and smelted, but I added them to other gold plated components in AR. I also added some very small nuggets from actual gold paydirt. So there must be some gold trapped in my waste products (which I have not disposed of yet). I have put my attempts at processing any more computer/electronic parts in stasis until I clearly understand the procedure for refinement. Whenever, I restart efforts, I'll certainly reduce as much extraneous starting material as possible. That change should take away a lot of the silver, copper, tin, lead, solder, etc. contaminants. I will only use a fraction of the HNO3 as before and add it incrementally. And, no more urea. I have acquired a tub of sulphalmic acid crystals. While things are on hold, I can harvest more scrap gold components from other computers/electronics. I guess the big question now is: Can I retrieve lost gold from my waste products, and if so, how do I proceed? Thanks and regards, edp

 

[Yggdrasil]

Again, thank you for the valuable info in your respones. It appears obvious to me now that I contaminated the initial batches with excess copper, tin, lead, etc. by not just consolidating the gold plated parts. I appreciate you for pointing out that fact. However, I believe that I did have some significant gold in the mixture. On my first attempt a couple months ago, I used a mixture of 45% acetic acid, 30% H2O2 and salt plus heat and an air bubbler to remove gold plating. Flakes of gold definitely came off and fell to the bottom of the beaker. Perhaps I should have just accumulated these flakes for a while and smelted, but I added them to other gold plated components in AR. I also added some very small nuggets from actual gold paydirt. So there must be some gold trapped in my waste products (which I have not disposed of yet). I have put my attempts at processing any more computer/electronic parts in stasis until I clearly understand the procedure for refinement. Whenever, I restart efforts, I'll certainly reduce as much extraneous starting material as possible. That change should take away a lot of the silver, copper, tin, lead, solder, etc. contaminants. I will only use a fraction of the HNO3 as before and add it incrementally. And, no more urea. I have acquired a tub of sulphalmic acid crystals. While things are on hold, I can harvest more scrap gold components from other computers/electronics. I guess the big question now is: Can I retrieve lost gold from my waste products, and if so, how do I proceed? Thanks and regards, edp

Yes it should be possible to reclaim the Gold, at least some.
But we need to know exactly what happened.

For the solutions, make sure ut is acidic by adding some HCl and then put in a slab of Copper.
This will cement out any values therein.

 

[Martijn]

Can I retrieve lost gold from my waste products, and if so, how do I proceed? Thanks and regards, edp

Yes. Solutions can go in the stockpot and solids can be processed.
Your gold is not lost.

 

[galenrog]

when it comes to recovering precious metals from a messy but acidic solution, we have a phrase that sends many of us in the correct direction.

“When in Doubt, Cement it Out.”

Yggdrasil gave you the basic method above. I would add a bit to it.

First, remove all solids. Note: This will also remove silver chloride if done properly. This is a good thing.

Second, ensure solution is acidic. Add HCl if needed.

Third, add a heavy copper bar to the solution. Many of us suspend the copper bar for easy removal. You will have to agitate the solution frequently in many cases, brush cemented material from the copper bar, utilize a bubbler, or, in some cases, all three. Fresh copper needs to be exposed for the reaction to proceed.

The reason for copper instead of another metal is that all precious metals, and little else in solution, is less reactive than copper. Copper enters solution. When saturated, gold and other precious metal in solution will fall out as a fine powder, sometimes black in color.

If my stroke addled brain got anything wrong, or left out anything, someone else will chime in to correct me.

Time for more coffee.

Edited for spelling and punctuation.