I'd like to share with my first success and problem

[magnalium]

Hello everyone!
I'd like to share with my first success, and soo... the first problem too.


First attachment is 0.8 g of gold scrapped form 850g random IC's
Generally IC's were incinerated, most of ashes separated by numerous sedimentation.
Most of magnetic metals were taken away, so Silicon, ash, copper and gold mixture were treated with AR+sulfuric acid. Gold from dirty solution was precipitated with Cu metal. (Im wondering is it this efficient method). After this gold was refined using AR and potassium metabisulfide.



Second atachment is an unknown compound (looks like iron compound)
It was produced while gold precipitation (similar to previous) from magnetic metal solution
I know the base magnetic metal is an alloy called kovar, containing mainly Fe/Ni/Co
I took a look into electrochemical series and figured out that, skipping all precious metals, only Co3+ could be reduced by Cu metal in this ammount. Is this possible that something oxidized Co2+ to Co3+?
I'm pretty sure there is most of my gold in there but have no idea how to separate it from vast ammount of this salt. I tried to dehydrate it and it turns dark red, quite strange for Cobalt. its insoluble in water, I must check how it works with acids.
Sorry for English, I'm not a native speker.



Have u got Some ideas, comment or tips?
PS I know the Hoke's holy bible

 

[Topher_osAUrus]

Gold from dirty solution was precipitated with Cu metal. (Im wondering is it this efficient method). After this gold was refined using AR and potassium metabisulfide.

I would say yes, when dealing with a dirty solution, cementing on copper is a great choice. I use copperas (ferrous sulphate) when precipitating gold from a solution that also has iron dissolved in it, it works well too.

To me, that second picture looks like gold, just a bit dirty,
Gold can be anywhere from light cinnamon color, to reddish brown, to black and anywhere in between.

I would redissolve the powder again in a minimal amount of AR, remove excess nitric with sulfamic acid. Maybe add a few drops of sulfuric too. Filter off any PbSO4, Ice the solution, double or triple its volume with the ice. Filter and remove the AgCl. If the solution is crystal clear, move on to precipitation, if not crystal clear then filter again until it is. Then suction bulb the barren solution from the precipitated gold powder. Then begin the washing process. Some choose hot water first, some do HCl. Alternate between hot water and cold HCl until the washes have no color to them. Then wash to neutral pH, dry and melt.

Looks like you have been doing great so far, good work! 8)

 

[magnalium]

Thanks for answer, I'll try my best to get some gold of it
For start as you wrote, I'll take small part of this and try to redissolve it.

One thing:

To me, that second picture looks like gold, just a bit dirty,
Gold can be anywhere from light cinnamon color, to reddish brown, to black and anywhere in between.

Im sure vast of it can't be gold, Why? The ammount, I didnt weighted it but looks for 50g+ of salt from a half kilo batch. It must be at least one of kovar's metal.

 

[Topher_osAUrus]

Well, copper only displaces nobel metals and mercury from solution.
So if you dissolved it all, cemented, dissolved the product of cementation and then used KMB to precipitate the gold. That is pretty selective.

Metabisulfite will only reduce gold from solution (well, copper chloride and palladium can be reduced as well, but thats if copper contamination is present and the pH is close to neutral, respectively)

So if I understood correctly, how you ran your process, there isnt much chance for other metal salts or metals to be contaminating the powder. But, I could be wrong.

Maybe take the powder, a small sample, and bring it to red heat. See if it begins to smoke off some impurities and discolors, or if it is gold and begins to anneal and become beautiful and shiny.

 

[g_axelsson]

The second sample looks like rust to me, it's a lot more orange than the gold powder. It could have formed from dissolved iron in solution. I would try to dissolve a small sample with hydrochloric acid as a first test.

Göran

 

[magnalium]

@Topher_osAUrus
I took 1.5 g sample, redissolved it in small quantity of AR, filtered, boiled out acids and filtered again. I obtained somehow dark yellow solution. (gold+iron?)
Next i added KMB an sudenny the solution turns dark brown (yes, it must have been iron there), after while adding more KMB, solution turns water-transparent, then light blue( residues of copper ions?), with tiny brownish particles suspended, visible on sunlight (gold?). After few hours Particles sedimentate.


@g_axelsson
U're right its iron(III)oxide
It dissolves well in muriatic acid creating FeCl3. I checked colors, its match perfectly.


Thank you guys for help, there's chance to rescue the gold

But i still wondering why does copper cementated iron oxide, and this oxide didn't get back to solution which was still quite acidic.

 

[Topher_osAUrus]

Did you test with stannous?

 

[Lino1406]

Copper will not cement iron, nor iron oxide. It is copper (di copper oxide) itself

 

[g_axelsson]

Copper will not cement iron, nor iron oxide. It is copper (dioxide) itself

Dioxide??? That would be Cu(IV) and that is an unstable olive green solid that easily breaks down to copper oxide.

Copper oxide is either CuO, a black solid or Cu₂O a yellow to red solid. Anyhow, both are soluble in HCl and forms green copper chloride, not an orange solution.

The second sample is most definitely iron based. If it dissolves in HCl then any gold should stay back as undissolved powder. But to be safe, test the orange solution for any gold dissolved.

Magnalium, to say exactly what happened to precipitate that much iron from your solution is hard, but with time and oxygen some iron might form oxides while the copper goes into solution as a copper chloride.
30 years ago I used iron chloride to etch circuit boards and I have a memory of the solution turning cloudy of rust. Maybe some similar reaction has happened here.

Göran

 

[anachronism]

Aye but let's not lose sight of the correct point Lino made Goran. Copper will not cement Iron.

In the past I've seen Iron and the rest of the metals come out of an AR solution when the HCl is exhausted but not the Nitric, and it's rammed with metals. I've posted pics somewhere of what happens when this occurs because it's a way to see an incomplete reaction due to lack of HCl.

 

[magnalium]

Did you test with stannous?

yes, I tested redissolved sediment from vial, its definitely possitive.

The second sample is most definitely iron based. If it dissolves in HCl then any gold should stay back as undissolved powder. But to be safe, test the orange solution for any gold dissolved.
Göran

Thats how I'm gonna separate gold, but firstly the powder goes to furnace to burn out all remaining nitric. Then i can be pretty sure theres no gold in solution after treating with HCl. Im right? //Seems we both like electronics tinkering, few years ago I used to etch my own PCB's too

In the past I've seen Iron and the rest of the metals come out of an AR solution when the HCl is exhausted but not the Nitric, and it's rammed with metals. I've posted pics somewhere of what happens when this occurs because it's a way to see an incomplete reaction due to lack of HCl.

At first sight the copper metal should react with nitric acid not muriatic. So HCl should still remain in solution.
But wait, Surely we have some Cu2+ and Cl- ions there, well Copper might be consumed by well known solution of HCl+CuCl2. So... if in this circumstances that reaction is faster than the reaction of Cu+HNO3, then you may have right.