Sciencemadness Discussion Board

Gold Recovery Computer Scrap Pentium Pro CPUs - VIDEO

kadriver - 30-12-2015 at 20:17

Here is a new video that I produced that shows how to use chemistry to recover and refine pure gold from four Pentium Pro CPUs

https://youtu.be/7OKTgdXbcEM

Comments welcomed!

Thank you

kadriver

Sulaiman - 31-12-2015 at 00:50

For me, the main problem with gold chemistry is that I am unable to determine the purity of my product to an accuracy that matches the level of purity that I am aiming for.
My local assay office charges would be about £33 (USD50) per test.
Although I can guestimate residual copper content by how green nitric acid becomes when weighed gold powder is added,
I have no idea how much platinum is present (or other stuff that dissolves in Aqua Regia but not HCl or HNO3)
So I have to ask ...
what is the purity of your final product, and how did you determine that ?

To minimise reagent usage
(Nitric acid is now precious for EU hobbyists, illegal by Sept.2016)
(Bucket loads of Sulphuric and Hydrochloric are OK so we can synthesise the nitric, but what a nuisance)
as near stoichiometric quantities should be used for all reagents.

(Just had a thought ... could a one pot HCl + H2SO4 + (a nitrate salt) dissolve gold in-situ ?)

When you added sulfamic acid after digesting the gold there was no fizz, and there were what looked like traces of gold left behing on the CPU packages
... not enough nitric acid used?

The video quality was good, clear steps.


diddi gave me a very good idea that you could consider: http://www.sciencemadness.org/talk/viewthread.php?tid=64561#...

I often find myself experimenting at stupid-o-clock in the morning, a common thing ?

EDIT:
On the subject of HNO3 availability
I imagine that a popular video would be gold recovery chemistry using OTC products, specifically 'nitric acid free gold recovery' or similar
e.g. include (or link to) nitric acid synthesis etc. or use H2O2 + HCl or Cl2 etc.

sorry if a bit negative, I'm having gold refining problems myself at the moment http://www.sciencemadness.org/talk/viewthread.php?tid=64759&...

[Edited on 31-12-2015 by Sulaiman]

Magpie - 31-12-2015 at 10:40

Beautifully done video, excellent lab technique, thorough processing. I love your use of kitchen utensils! :D

aga - 31-12-2015 at 11:20

Nice video !

Why are you using conc HCl for washing the gold powder in the filter paper ?

Well, it fumes, so looks conc.

I suspect that if you did not immediately rinse with water, the conc HCl would eat through the paper (bet that's happened once or twice).

cyanureeves - 31-12-2015 at 21:35
Quote:

(Just had a thought ... could a one pot HCl + H2SO4 + (a nitrate salt) dissolve gold in-situ ?)
yes, ebay "used to" sell these chemicals together as a kit for gold recovery.

[Edited on 1-1-2016 by cyanureeves]

kadriver - 2-1-2016 at 09:10

Quote: Originally posted by aga  
Nice video !

Why are you using conc HCl for washing the gold powder in the filter paper ?

Well, it fumes, so looks conc.

I suspect that if you did not immediately rinse with water, the conc HCl would eat through the paper (bet that's happened once or twice).


Hello aga,

If you look closely at the filter paper when rinsing with concentrated HCl then you will see a yellowish green color appear around the edges of the filter paper. This is iron, that is yet present, in solution, soaking the gold powder. You can see the yellow color in the HCl as it runs out the bottom of the funnel. Water alone may wash the iron out. But by using HCl I get this wonderful color indicator that tells me when all the iron is gone. When the HCl filtrate runs clear then I know the iron is rinsed out of the gold. Water along will not turn color so I can't tell when all the iron is rinsed out.

I have gone back after the water wash and repeated the HCl wash, especially if there is lots of iron present. This second HCl wash will reveal the iron is still present, but in much less quantity.

I've never had a filter paper fail while rinsing with hydrochloric acid. But I have had filter papers fail when trying to vacuum filter a hot silver nitrate solution. Sulfuric acid - forget it. Sulfuric acid will almost immediately eat through a filter paper on contact. Of the three acids, hydrochloric has never given me a problem. Now that I've said that, my next batch of filtered gold will have a filter paper failure from the HCl rinse!

kadriver

kadriver - 2-1-2016 at 09:22

Quote: Originally posted by cyanureeves  

Quote:

(Just had a thought ... could a one pot HCl + H2SO4 + (a nitrate salt) dissolve gold in-situ ?)
yes, ebay "used to" sell these chemicals together as a kit for gold recovery.

[Edited on 1-1-2016 by cyanureeves]


There still is at least one eBay seller under listing titled "Scrap Gold Refining Kit - EVERYTHING YOU NEED".

The kit has sodium nitrate, urea, and sodium metabisulfite.

Check "indeeditdoes" on youtube. He does a batch of CPUs (not Pentium Pro) and he uses sodium nitrate and some other acids to form nitric acid. Then he adds HCl to form the Aqua Regia that will dissolve the gold in his video.

kadriver

kadriver - 2-1-2016 at 09:40

Quote: Originally posted by Sulaiman  
For me, the main problem with gold chemistry is that I am unable to determine the purity of my product to an accuracy that matches the level of purity that I am aiming for.
My local assay office charges would be about £33 (USD50) per test.
Although I can guestimate residual copper content by how green nitric acid becomes when weighed gold powder is added,
I have no idea how much platinum is present (or other stuff that dissolves in Aqua Regia but not HCl or HNO3)
So I have to ask ...
what is the purity of your final product, and how did you determine that ?




[Edited on 31-12-2015 by Sulaiman]


Hello, I've refined dozens if not hundreds of gold bars in the last five years. I usually send them in to a big refiner who pays me 98 percent of spot, based on the purity of my metal that I send in.

They have a fancy machine called an XRF that they use to determine the purity of the metal that I send them. After they "shoot" my gold and get a value on the purity, then they use that number to calculate the amount that they pay me.

It is ALWAYS 999 fine gold. This means 99.9% purity - every time. When I do a batch of gold I always refine it to the highest level that I know how to do.

By practicing this I can be quite confident that any gold that I refine, using the methods in shown in my video, will be 999 fine, every time.

kadriver

Heavy Walter - 2-1-2016 at 10:57

Hi kadriver

Excellent procedure!
May be I lost the info, but: how many boards do you need in order to make a profit against all your expenses?
Are you dealing with kgs or tons?

aga - 2-1-2016 at 11:00

As kadriver explicitly said in the video, the aim was to make the video, not to make a profit.

To make money with this process you need to either get the boards for free or process some serious tonnage on a monthly basis.

Heavy Walter - 2-1-2016 at 11:07

Thanks aga,

I didn't get that when watching the video.

aga - 2-1-2016 at 11:13

You *can* make money at it, just that you need to do it on a big scale to actually make a profit.

You'd make more money selling sandwiches, burgers or hotdogs.

Heavy Walter - 2-1-2016 at 12:22

Yes... but no fun for chem lovers!