Connectors Ref. Going wrong

[Blue01]

Hello guys.

Any suggestion welcome.

We have trouble with refining 20kg of connectors.

I clean them and leave them in HCL to remove SN from surface.
After that we us AR solution. Connectors dissolve, we wash plastic and filter solution.
I use sulfamic acid to neutralize Nitric like i use always. Solution is dark,dark green. After that i add whater to solution and add some SMB diluted i little quantity of water.
I leave that 24h but nothing happen, i tried to add more smb but still no reaction . I toke sample and try to ad ferrous sulfate but also no reaction.
Then i cemented all with ALU foil to see what i will get.
I wash and dry slug that i got from solution and i have analyze the dust.
I get readings from the picture.

Connectors :
https://ibb.co/JHRfPmj

XRF :
https://ibb.co/Jm6DxX7

I still have approx. 25-30l of diluted AR.

Why do think that i failed , is it because Sn or? And what you suggest me to do next wit the solution?
How to extract Au with no big losses?

 

[canedane]

When things getting wrong, drop with copper.
You HCl wash should have taken the Sn, Ni and Pb, you diddent use HCl enough or you did the proces to quickly.
Get the Pb,Ni, Zn and Sn out before you use AR.
Did you take a stannos test?
Now you know how mutch gold there are (1,1%) you can calculate how mutch nitric you need.
Henrik

 

[butcher]

Blue01



Mostly, because you are trying to use a refining process , instead of first using a recovery process to recover gold from a mix of base metals.

You would do better to learn a better methods of recovering the gold before attempting to refine it.
I suspect excess nitric was used, and the free nitric and nitrates were not properly removed from solution before trying to precipitate the gold from a slurry of base metals.

Using copper would have given you a cleaner precipitant of the gold, than the aluminum which will precipitate many of the base metals along with the gold.

Your stannous chloride can tell you if there is free nitric in solution, as well if there is gold in solution, your stannous chloride will not form a colloid or the purple of Cassius if excess free nitric is in solution redissolving the metal gold colloid, (base metal nitrate salts will not effect your stannous chloride test. but with any addition of acid HCl, sulfuric, or any other types of acids would reform free nitric acid in solution from the acid and base metal nitrate salts chemical reacting together.

You can use copper to cement the values from the base metal soup. and then recover the gold from the mix of base metal powders, there are several ways or methods to choose from, to recover the gold, cupric chloride would be one way to leach base metals from the gold before refining the gold.

 

[g_axelsson]

What does a stannous test show you on the diluted solution?

... and why adding water after aqua regia? Is this some new idea floating around?
I've never had a reason to add water to dilute my gold chloride solutions. It creates more waste and only makes it slower to precipitate the gold. The only time I can see any advantage is if you are working with carat gold in highly concentrated solutions and want to eliminate silver chloride.

As for the first picture, I hope you cleaned up that scrap better before going to acid. I could see large pieces of painted iron in that pile. As you probably know, having any metal left in your aqua regia is a possible way to lose gold. Painted and buried metal (as the inner layers in the circuit board pieces) can sometimes cement gold out of sight.

Göran

 

[Blue01]

Hello.

First of all thank you for the help.
We are in autocatalyst and E-Waste bussines. Most of our material we export to our partner refinery's in EU but start from last year i start experimenting with refining of relatively expensive material that we buy from time to time.

In this phase this is still hobby for me and i don't know much. I read a lot especially on this forum and watch thousand of videos but still did not scratch the surface.

Today i test the solution i attached picture. Solution is diluted so it is light green as you can see left when i add stannous i have strong reaction but after couple of minutes this get slightly brighter (suppose from the excess free nitric that is not convert with sulfamic) , now it is dark-dark green not black but still reaction is still there.

This procedure that i describe i use for ceramic cpu and gold fingers and works fine but this material don't have lot of base metals and here that is the problem. I did not expect that it will be that much of Tin here.

Last time that i try to refine some pins i treat them first with Nitric but with gold foils i got lot of Tin and have trouble to separate Tin from gold foils but this is other topic. I wrote this problem and i got some tips that i must try these days.

I know for copper cementing procedure i use it for my stockpot that i collect i add coper metal and bubler. From time to time i add some hcl to get reaction going but this need very long time probably month or two.

Today i check this method with cupric chloride that butcher mentioned, i watch couple of videos that i find. As i understood basically it is same like cementing with copper? It is Copper chloride so probably reaction will be faster than with coper but still i saw that people leave it for month to finish reaction. It is really long time.

https://ibb.co/GttnD37

I don't need to add water to solution ?
When i start wit refining i read on couple places and watch that people add water. They say that reaction is better when they add SMB. Also if they have dirty solution they dilute SMB in water and ade it like that.
I took that that as rule and start adding water.

Every refining process i work 2 time, first time we don't get fine gold and i rerefine that and again add distillated water and finish procedure. This way i get 999.9.

My English is not perfect, sorry if i misspell somethin.

 

[Martijn]

Your gold may be in the first filter after AR, depending on how much nitric you used. The dissolved gold will keep cementing out on the last bit of base metals left during the reaction.

Testing a solution with a lot of base metals will give a false positive. Hard to spot any gold present.

You basically allready made AP in your stockpot and added HCL. So its fresh to use if you take the copper out. You can use that to dissolve more base metals.

To get rid of tin paste in your foils: incinerate and leach the tin out in HCL. Then go for the gold with AR.
Carefull with a torch. Heat from underneath. Foils get blown out easily.

Try to keep your pregnant solution concentrated. Only chill with an ice cube before filtering and SMB. It gives a better precipitate that settles and washes a lot better.

Test one drop of solution instead of a full spot plate hole. It will give a better visible test result. And if its too dark, you have enough room to dilutue it with a drop of water.

Martijn.