Remove Copper from Sulphuric Stripping cell

[gregory-d]

Ok after a few failures gold is stripped and there somewhere but after the SMB I have nothing.
Before I try again or just give up I am trying to clean up my act.
So even though I have tried to be careful I with power current and voltage.
I am still ending up with copper solids in the sludge at the bottom of my cell.
I think I am just taking it too far or that the sulphuric is now polluted and other stuff is going on.

From what I have read I believe that if I reverse the polarity with a lead anode and copper cathode
(I think I have that the right way around) that will electroplate the copper out of solution.
Also the next lot of sludge that looks like it has copper in it. Last time there was a lot of lighter sludge with it I am guessing that is copper.

I am thinking that I can dilute the sludge then add nitric to remove the copper from the sludge leaving mostly gold sludge.

-Filter out the solids.
-add HCL to the liquid. then if there is any reaction add SMB to drop any gold. (I will make an SO2 bubbler later to do that in a cleaner way)
-do the AR on the remaining sludge and filters when there is a reasonable amount.

Is this the correct way to sort this all out?
Clearly I am getting a little muddled at the moment.
I have been reading a lot but it is all a bit of a jumble in my head at the moment.

 

[Yggdrasil]

Ok after a few failures gold is stripped and there somewhere but after the SMB I have nothing.
Before I try again or just give up I am trying to clean up my act.
So even though I have tried to be careful I with power current and voltage.
I am still ending up with copper solids in the sludge at the bottom of my cell.
I think I am just taking it too far or that the sulphuric is now polluted and other stuff is going on.

From what I have read I believe that if I reverse the polarity with a lead anode and copper cathode
(I think I have that the right way around) that will electroplate the copper out of solution.
Also the next lot of sludge that looks like it has copper in it. Last time there was a lot of lighter sludge with it I am guessing that is copper.

I am thinking that I can dilute the sludge then add nitric to remove the copper from the sludge leaving mostly gold sludge.

-Filter out the solids.
-add HCL to the liquid. then if there is any reaction add SMB to drop any gold. (I will make an SO2 bubbler later to do that in a cleaner way)
-do the AR on the remaining sludge and filters when there is a reasonable amount.

Is this the correct way to sort this all out?
Clearly I am getting a little muddled at the moment.
I have been reading a lot but it is all a bit of a jumble in my head at the moment.

The stripping cell do not put the Gold into solution permanently.
So SMB will have no effect.
The Gold is already in metallic form.

 

[gregory-d]

The stripping cell do not put the Gold into solution permanently.
So SMB will have no effect.
The Gold is already in metallic form.

Yeah I didn't explain that very well
I do that after the AR on the sludge.
here's what I plan to do next time step by step
1 stripping cell
2 syphon of all but the sludge in the bottom (return the rest to the cell)
3 dilute the sludge
4 if sludge is not totally black add nitric to dissolve and remove the copper from the sludge
5 filter (this should be mostly gold but the rest is to refine it further. But as the liquid may contain some gold save it for later cementing out)
6 add HCl and heat.
7 @ 70C add very small amounts Nitric and wait until no reaction
8 denox with urea or gold
9 add SMB (later SO2 will replace SMB) in small amounts until no reaction
10 add extra dilute HCl and evaporate.


Also to clean the sulfuric cell
I reverse the polarity ie copper cathode and lead anode to remove copper pollution from sulfuric if there has been copper in the sludge.

Have I got this right or am I still miss-understanding something?

 

[Martijn]

I would boil the diluted acid in step 3 for at least 10 min.
Then the Urea should be left in the garden fertilizer closet.

Dilute HCL after SMB has no purpose as far as i know. why were you thinking this?

After digestion of the gold, dilute with water (to push out AgCl that is slightly soluble in HCl) and add sulfuric to push out lead or add sulfamic if you have too much HNO3 left in solution, this will also push out lead as insoluble lead sulfate.

Next and most important step is filtering the solids and insoluble salts from solution through the same filter until the gold chloride is crystal clear.
This helps you refine the solution by easily separating dissolved salts from solids and insoluble salts, which is the whole point of hydrometallurgy. Pull it apart, convert some of it chemically and separate it by filtering.
Filtering it very thoroughly is overlooked a lot by new members.

After SMB there is no need to add dilute HCl, in fact it is better to wash in hot and strong HCl first to dissolve any AgCl. That will give a yellow color, much like AuCl does. Wash until the washes stay clear.

Perform step 7 in a beaker with a loose glass lid on it, to condense any NO2 and NOx into HNO3, and you'll be using very little HNO3.
at the end, open the lid to let those gases escape and you'll have little to no Nitric to denox.
be patient, HNO3 can still be active and digesting at a slow rate, impatience is always the reason for free nitric in solution.

have fun, stay safe.

 

[gregory-d]

Thanks heaps Martijn that fills a lot of holes in my understanding.

I would boil the diluted acid in step 3 for at least 10 min.
Then the Urea should be left in the garden fertilizer closet.

Excellent I was hoping to do as little denox as possible. When I get some gold I will use that just to be sure and as you say leave it for the garden

Dilute HCL after SMB has no purpose as far as i know. why were you thinking this?

This step seems to be skipped in all the stuff I've seen I did see it needed washing and that is what I thought this meant. To remove anything that may still be there.

After digestion of the gold, dilute with water (to push out AgCl that is slightly soluble in HCl) and add sulfuric to push out lead or add sulfamic if you have too much HNO3 left in solution, this will also push out lead as insoluble lead sulfate.

I saw that sort of but didn't really understand it now thanks I do.

Next and most important step is filtering the solids and insoluble salts from solution through the same filter until the gold chloride is crystal clear.
This helps you refine the solution by easily separating dissolved salts from solids and insoluble salts, which is the whole point of hydrometallurgy. Pull it apart, convert some of it chemically and separate it by filtering.
Filtering it very thoroughly is overlooked a lot by new members.

Yes it is tricky to understand which filtering does what job.

After SMB there is no need to add dilute HCl, in fact it is better to wash in hot and strong HCl first to dissolve any AgCl. That will give a yellow color, much like AuCl does. Wash until the washes stay clear.

This bit is still a little confusing the washing part.
Ok so the hot strong HCL pushes out the silver chloride (it is easy to get Au and Ag muddled when I read stuff sometimes)
The wash continues with hot HCl until it is clear.
Is that right?

Perform step 7 in a beaker with a loose glass lid on it, to condense any NO2 and NOx into HNO3, and you'll be using very little HNO3.
at the end, open the lid to let those gases escape and you'll have little to no Nitric to denox.
be patient, HNO3 can still be active and digesting at a slow rate, impatience is always the reason for free nitric in solution.

Thanks that makes it more clear.

have fun, stay safe.

Yep I am even though I have failed many of the things are easier to understand now I have actually done it.
I have to build a proper hood now as I have already eaten the wires in the fans in my first basic attempt which was simply to get started so I knew it wouldn't last. But yes even a whiff of Chlorine from the HCl is enough to bother me these days so I going to build a proper one with a scrubber and all. So that will give me some breathing space to absorb this all before I go again.

Thank you so much.

 

[gregory-d]

Can I just ask if my reasoning is correct here?

To clean the sulfuric cell
I reverse the polarity ie copper cathode and lead anode to remove copper solution from the sulfuric.

 

[Shark]

Just a little tip to help clear up confusing Au and Ag. It will also lead to less confusion later on as you learn more.

Any time I see Au or Ag when reading, mentally I pronounce them as the word. So when I see Au in my mind I pronounce it as gold or Ag as silver. Later as you learn more of the chemistry, you will notice others as well like H2So4, or pronounced as sulfuric acid.

 

[Martijn]

Ok so the hot strong HCL pushes out the silver chloride

No. The diluting of the pregnant solution ( so before SMB) will push out any silver chloride before filtering.
Then filter well and most AgCl is gone.
SMB pushes out the gold and to wash the powder, after settling and decanting, you don't want to push out AgCl by adding water, but keep it soluble by washing in hot HCl. This keeps any AgCl in solution and can be decanted off. Repeat until washes are clear and colorless.

Read this:
https://goldrefiningforum.com/posts/2620/
The Ammonia step can be left out and done cold.

 

[Yggdrasil]

Can I just ask if my reasoning is correct here?

To clean the sulfuric cell
I reverse the polarity ie copper cathode and lead anode to remove copper solution from the sulfuric.

No it will not push the Copper back.

 

[gregory-d]

No. The diluting of the pregnant solution ( so before SMB) will push out any silver chloride before filtering.
Then filter well and most AgCl is gone.
SMB pushes out the gold and to wash the powder, after settling and decanting, you don't want to push out AgCl by adding water, but keep it soluble by washing in hot HCl. This keeps any AgCl in solution and can be decanted off. Repeat until washes are clear and colorless.

Haha yep I'm using the wrong terms AGAIN by pushing out I meant diluting or pushing it out of the solid state.
But thanks the extra clarification does help.
I wasn't sure if the washing was in water or hot HCl but now it is completely clear.
Thanks

Read this:
https://goldrefiningforum.com/posts/2620/
The Ammonia step can be left out and done cold.

I definitely will Thank you so much for your help in this.

 

[gregory-d]

No it will not push the Copper back.

Thanks Yggdrasil I wasn't sure. I was hoping I could just electroplate the copper sulphate out of the solution if it had formed.