I need help separating Ag and Au from my sludge.

[conglioa]

Hi everybody!
With the analysis results as attached image I need help with the most efficient procedure to separate gold and silver from the anode sludge.
Currently I have about 40-50 tons of dry sludge with the composition as shown in the image analysis results.
I tried to separate silver by sulfated method, it works but it is difficult to separate the residue and solution from each other because they form a very fine mud after dissolving with water. It is difficult to wash off silver sulfate from the residue.
I tried separating Gold from the residue after separating Silver with about 500g of sample. I used AR 2 times and tried it with negative Stannous chloride for the first time.
In the 2nd AR, the Stannous chloride test was positive, but after I finished the process I had a little more water to cool before separating the residue and solution from each other, the test with Stannous chloride was negative.
Can you explain for me why there is a positive then negative for gold as I just mentioned.
And if anyone has experience dealing with copper-refined electrolytic anode sludge can you help me get a very efficient process.
I would like to thank and acknowledge all of your concerns.

 

[nickvc]

If it were me I’d be tempted to melt the slimes and re run them through a copper cell to increase the precious metal content, with the high water content you may well have a product that will run fairly successfully without fouling the electrolyte.
Trying to recover values that low will make it expensive especially as 1/2 is still copper so if anyone knows of a method to concentrate the values other than my suggestion please comment.

 

[conglioa]

If it were me I’d be tempted to melt the slimes and re run them through a copper cell to increase the precious metal content, with the high water content you may well have a product that will run fairly successfully without fouling the electrolyte.
Trying to recover values that low will make it expensive especially as 1/2 is still copper so if anyone knows of a method to concentrate the values other than my suggestion please comment.

Hi, thank you very much for your interest.
Currently I have a plan to treat 1/2 amount of copper in which the effect is to heat with concentrated sulfuric acid, then dissolve in water, all the copper will be dissolved into copper sulfate solution and then returned to electrolysis to recover copper. The remaining residue I continue to heat with concentrated sulfuric acid 2 times to convert silver to silver sulfate and dissolve in water and copper cement.
But I had difficulty in the filtration process to separate solid residue and silver sulfate solution from each other because the sludge is very fine and thick.
The amount of silver sulfate remaining in the solid residue is about 10%.
And the residue left now I have not found an effective way to separate the gold, so it is very necessary for the help of the experienced guys.

 

[nickvc]

With the quantities you have to treat you will be working on this full time for a very long time hence my suggestion of casting the material into fresh anodes and run them in a separate cell, to make precious metal recovery viable you need to increase the precious metal content in your slimes, once run the slimes may well be treated in a silver cell to recover the silver leaving the gold and other metals in the slimes and now well worth spending time on.

 

[conglioa]

With the quantities you have to treat you will be working on this full time for a very long time hence my suggestion of casting the material into fresh anodes and run them in a separate cell, to make precious metal recovery viable you need to increase the precious metal content in your slimes, once run the slimes may well be treated in a silver cell to recover the silver leaving the gold and other metals in the slimes and now well worth spending time on.

I have thought of the option as you said, but one problem I have been advised is that reheating the sludge in a reactor will lose a lot of precious metals because it can go and mix slag, smoke ... and then I didn't notice the idea anymore.
Thank you very much for the advice and I will seriously reconsider that option. But if I want to reheat I have to wait for its weight to reach about 70 tons because my furnace capacity is about 70 tons of copper / batch.
And I cannot invest in a separate cooking system for this sludge because the cost and time involved in it is very small.
Such sludge accumulates over a period of more than 2 years.

 

[etack]

If you want this out of the way you could just buy 40 tons of cooper to add to it.

It might be worth the $380,000 in PM value and you would still have the Cu too.
Seems like a Cu smelter would be good for this. Might want tho spread this out on tarps to dry it out too.
Eric

 

[conglioa]

If you want this out of the way you could just buy 40 tons of cooper to add to it.

It might be worth the $380,000 in PM value and you would still have the Cu too.
Seems like a Cu smelter would be good for this. Might want tho spread this out on tarps to dry it out too.
Eric

the analysis results are when the sludge is still wet. now it is down to about 10% H2O. I plan to use a sulfated method to recover silver. As for gold, I don't have any really effective methods yet. I want to find an effective hydration method that does not require retraining. Hope someone in the same field can give me really useful advice with what I have.

 

[g_axelsson]

Maybe this article could be an interesting read.

https://doi.org/10.1179/174328509X431463 Processing of copper electrorefining anode slime: a review

I got it from https://sci-hub.st/ where I get a lot of my research papers.

The traditional process steps including soda roasting,
selenium leaching, copper leaching, smelting, refining
and silver and gold electrolysis.

... and then they go on and tells us that it isn't used any more by the larger refiners and then lists a number of ways the slime can be treated as well as references to articles describing different ways it is done today. Both pyrometallurgical, wet chemistry methods and combinations of both.

One major difference is if the copper comes from mining or recycled copper, the contaminants and processing differs between them.

Göran

 

[etack]

If you want this out of the way you could just buy 40 tons of cooper to add to it.

It might be worth the $380,000 in PM value and you would still have the Cu too.
Seems like a Cu smelter would be good for this. Might want tho spread this out on tarps to dry it out too.
Eric

the analysis results are when the sludge is still wet. now it is down to about 10% H2O. I plan to use a sulfated method to recover silver. As for gold, I don't have any really effective methods yet. I want to find an effective hydration method that does not require retraining. Hope someone in the same field can give me really useful advice with what I have.

Seems what you have is feed-stock for a Cu smelter.

Not too sure what the sulfate method is but let us know.

Also what field are you in that might help us understand what you have.

Eric

 

[conglioa]

[/quote]
Seems what you have is feed-stock for a Cu smelter.

Not too sure what the sulfate method is but let us know.

Also what field are you in that might help us understand what you have.

Eric
[/quote]

Thank you for your interest.
I am currently working at a copper refining factory in Vietnam, we go from scrap copper raw materials, through fire treatment and electrolysis to collect pure copper.
The anode sludge electrolysis process which contains a lot of copper and some precious metals such as gold and silver according to the analysis results I attached.
I am an analytical chemical engineer, responsible for researching the plant's anode sludge treatment solution to recover copper, gold and silver.
But what makes me difficult is that I do this alone, too much work, too many documents I can find so I cannot handle everything. I spent a lot of time researching and found that a suitable method is sulfation. I can summarize the process I'm working on in the lab as follows:
1. Sludge after being dried and crushed will be heated in a gas furnace and air oxygen at a temperature of 500 - 600 degrees C.
2. The sludge after calcination will be heated with the concentrated sulfuric acid until all components are converted to sulfate (I call sulfated).
3. The sludge mixture, after being heated with the concentrated sulfuric acid, will be dissolved in water, heated to 100 degrees C for 3 hours. Then the solution and residue will be filtered by a centrifuge. I will test the solution if there is Ag2SO4 I will cement them with copper.
4. If the solution doesn't have silver I will send it back to the electrolysis system to recover the copper. Through filtration with water about 95% of the copper in the mud will be dissolved and recovered.
5. The residue I continue to sulfate 2 times (ie repeat steps 2 to 3)
6. The solution part after sulfated and water filtration for the second time will definitely contain Ag2SO4 because it does not get copper in cement mud again. Then I will separate the solution and cement with copper to collect copper powder.
My problem is that the residue after sulfation is very fine so it is difficult to filter and wash off the silver in it, at the moment I don't know how to make it easier to filter, I am learning some filtration aids but don't know whether it affects the sludge quality.
And the residue after recovering the copper and silver has all the gold in it, I have no way to effectively separate the gold, so I need the help of anyone experienced in the forum.
As I said that my current job is only me doing, partly because my knowledge is limited, the current job is not the subject I study, partly because there are too many documents to study. like conducting experiments. So I chose to ask the help of the members of the forum, hoping to shorten the research time.

 

[conglioa]

Maybe this article could be an interesting read.

https://doi.org/10.1179/174328509X431463 Processing of copper electrorefining anode slime: a review

I got it from https://sci-hub.st/ where I get a lot of my research papers.

The traditional process steps including soda roasting,
selenium leaching, copper leaching, smelting, refining
and silver and gold electrolysis.

... and then they go on and tells us that it isn't used any more by the larger refiners and then lists a number of ways the slime can be treated as well as references to articles describing different ways it is done today. Both pyrometallurgical, wet chemistry methods and combinations of both.

One major difference is if the copper comes from mining or recycled copper, the contaminants and processing differs between them.

Göran

Thank you.
I spent the last night researching the resources you provided. I found something that would benefit my job right now, but there are a lot of processes involved that require me to do a lot of experiments to find the method that best suits the amount of sludge I currently have.
Anyway thank you very much, good day for you and your family.

 

[kurtak]

It might be worth the $380,000 in PM value and you would still have the Cu too.

According to the read out he posted gold content is .0043%

2,000 pounds (one ton slimes) X .0043 = 8.6 pounds

8.6 X 454 grams (about a pound) = 3,904.4 grams

3,904.4 divided by 31.1 grams (an OZT) = 125.543 OZT

125.543 X $2,000 = $251,086.81 (per ton)

he has 40 - 50 tons --- At 40 tons it is over 10 million $

Kurt

 

[conglioa]

It might be worth the $380,000 in PM value and you would still have the Cu too.

According to the read out he posted gold content is .0043%

2,000 pounds (one ton slimes) X .0043 = 8.6 pounds

8.6 X 454 grams (about a pound) = 3,904.4 grams

3,904.4 divided by 31.1 grams (an OZT) = 125.543 OZT

125.543 X $2,000 = $251,086.81 (per ton)

he has 40 - 50 tons --- At 40 tons it is over 10 million $

Kurt

I think you're a bit confused.
If the gold in this sludge is only about 69 oz / 50 tons: D
If the value is calculated it will not be about 21000oz Ag / 50 tons of sludge
But what I am more interested in is the method for separating those valuable metals otherwise it is just mud :lol:

 

[g_axelsson]

Counting with imperial measurements makes my head hurt!

0.0043% = 0.000043 = 43 / 1000000 = 43 grams per ton (1000 grams per kg, 1000 kg per ton)

43 * 50 tons = 2000 g gold = 2 kg gold

It might be just mud, but it will never be just common mud.

Göran

 

[conglioa]

Counting with imperial measurements makes my head hurt!

0.0043% = 0.000043 = 43 / 1000000 = 43 grams per ton (1000 grams per kg, 1000 kg per ton)

43 * 50 tons = 2000 g gold = 2 kg gold

It might be just mud, but it will never be just common mud.

Göran

This is the correct calculation.
It is royal mud, but also just ordinary mud if there is no plan to treat it.
And I'm trying so that it's not worthless, discarded mud :lol:

 

[etack]

Counting with imperial measurements makes my head hurt!

0.0043% = 0.000043 = 43 / 1000000 = 43 grams per ton (1000 grams per kg, 1000 kg per ton)

43 * 50 tons = 2000 g gold = 2 kg gold

It might be just mud, but it will never be just common mud.

Göran

My numbers were also based on it having 40% water I used 30 tons for my calculations.

Eric

 

[kurtak]

:lol: that's what I get for reading the thread & then posting a quick reply about ten minutes before heading out the door for work & not taking more time to better look at it :roll:

So my bad & thanks for correcting me (you guys are great) :mrgreen:

anyway - it would be good if maybe 4metals could chime in on this one - or Lou

Also - I have a friend that is a teacher at the university of Nevada (Reno) that teaches mining/mineral processing & metallurgical engineering & he will be up here at his property here in Oregon this week end so I will run this by him to see what he thinks

He does consulting for VERY large operations so he may (or not) want a consulting fee

If he is interested in helping with this I will look into putting him & conglioa together on this matter

So I will report back after talking to him this week end

Kurt

 

[kurtak]

conglioa

Ok - I did talk to my friend this week end - however because others had been invited for a get together (about a dozen other people) I did not have a lot of time to talk to him

I printed out this discussion/thread to show to him - which he looked at (including the analysis print out you posted)

Based on the analysis & what you posted - he agreed with what Nick posted

In other words - he said - with that much copper he would "first" melt it - pour new anodes & re-run it in a copper cell thereby further reducing the copper content & increasing the gold/silver content in the slimes of the second cell run & then process the slimes for the gold & silver

He made mention of three or four methods of processing "those" slimes (second run in the copper cell) including but not limited to method you have posted - however with the larger get together of friends did not have time to go into details on those methods

The bottom line being that in his opinion - the best way forward - due to the high copper content would be to re-melt/smelt the slimes - re-pour anodes & re-run them in the copper cell to reduce copper content & increase gold/silver content making processing of the slimes (to recover gold & silver) more effective

Kurt

 

[kurtak]

Also - I have contacted another friend about this (left him a message) so am waiting to hear back (I just contacted him this morning

He is another person - that if anyone has answers - he will (likely) have answers

He is a busy man so we will have to wait & see - so hang in there

Kurt

 

[nickvc]

The reason I suggested this method is the very large percentage of base metals and very very low percentage of precious metals, this is uneconomical to process using acids, another method that might work would be to use a very weak cyanide leech which would be much more selective in recovering the values, the only problem would be the acid content in the slimes which would need neutralising, Deano might have some thoughts on this as he has great experience in selective leeching using cyanide. The downside would be large volumes of solution but again perhaps Deano could suggest a viable method.