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Yggdrasil said:
Sorry for not welcoming you in a proper way.
I'll try again :)
Welcome to us

Here is our forum rules and other important links for your studies:

We ask our new members to do 3 things.
1. Read C.M. Hokes book on refining jewelers scrap, it gives an easy introduction to the most important chemistry regarding refining.
It is free here on the forum: Screen Readable Copy of Hoke's Book
2. Then read the safety section of the forum: Safety
3. And then read about "Dealing with waste" in the forum: Dealing with Waste

Suggested reading: The Library

https://goldrefiningforum.com/threads/gold-refining-forum-rules.31182/
Click to expand...
Thank you 😋
 
Deano said:
For the last few weeks I have been processing an electrowin sludge from a gold/copper mine carbon strip plant.

The sludge is formed from the cathodic reduction of metals solubilised from the stainless steel anodes in the electrowin cell.

Major metal components of the sludge are manganese, nickel and chrome.

The sludge contains around 1% gold with some silver, no PGMs.

The sludge also contains high levels of chloride from the strip circuit water.

As an electrowin product, the gold is encapsulated in the manganese and is not in the main accessible for cyanide leaching.

The dry product is a fluffy brown solid which becomes a brown slime, virtually unfilterable, when wet.

As there are a few hundred kilograms of this material the operator was quite interested in recovering the gold values.

If the sludge is placed in acid solution and the mangaqnese dissolved around 70% of the gold also instantly dissolves as a gold chloride.

If placed in a pressure filter I could only filter 5 litres of liquor in 24 hours from this pulp.

The first requirement was to improve the filtration of the pulp.

I did this by furnacing the dry sludge for 8 hours at 500C.

The operating temperature range was 450 to 550C, furnacing outside of this range caused further problems.

The furnaced material was then digested in HCl and enough HNO3 was added to drive the gold dissolution to maximum values.

An attempt was made to put the gold values from this pulp onto carbon however the manganese swamped the carbon and allowed only low gold adsorption.

I then took the pulp and added NaOH to a pH around 10.

All of the metal values including the gold precipitated out.

I then added cyanide to the pulp at 3 times stochiometric for the gold values and solubilised just the gold and silver.

As the gold had precipitated rather than been electrowon it was accessible to a cyanide leach.

The pulp was then pressure filtered and the liquor was contacted with carbon and the gold loaded thereon.

The carbon was later ashed with the ash digested in aqua regia and the gold recovered with metabisulfite.

Note that the gold could not be recovered from the filtered liquor by electrowinning as there was a high chloride level in the liquor which would lead to high chlorine evolution levels.

The gold levels at all stages were monitored by AAS and residues were assayed by aqua regia digest.

It appeared that the initial sludge was an artefact of attack on the stainless steel anodes by the copper rich strip solution.

The treatment process I developed is not the only one possible but is what I felt was the most cost effective.

If the above can help anyone with a similar problem feel free to use it.


Deano
Click to expand...
Thank you, Deano For your well-tabulated presentation. It has given me much food for thought,
 
Deano said:
I was a bit rushed when I posted the last effort.

What I was wanting to say but missed doing so was that the post was really about the effect in a leach of having manganese in solution.

For most people this involves an acid leach, having manganese in solution in alkaline solution is not an everyday procedure.

Having manganese in solution means that any gold present will not precipitate out until the manganese has been itself reduced to Mn2+.

You can be adding precipitating agents in industrial quantities to achieve this depending on the manganese levels.

The idea of adding a whole lot of reductant such as metabisulfite to the solution usually results in the dropout of brown manganese complexes as well as the gold, there is a small window where only gold is precipitated.

If someone has a solution which has known gold dissolved but which will not drop this gold when the correct amount of precipitant has been added then the presence of manganese in solution should be investigated.

The presence of manganese in solution also interferes with solvent extraction both in the loading cycle and the phase separation stages.

Manganese in solution will usually be sourced from having stainless steel present in the leach step.


Deano
Click to expand...
How to reduce manganasse to Mn2+ friend?
 
Riyan said:
How to reduce manganasse to Mn2+ friend?
Click to expand...
Aah, I see now.
You want to remove the Manganese to drop Gold?
If there is a problem dropping the Gold, it is recommended to Cement on Copper, which will leave the Mn intact in solution.
Then collect the dropped Gold and redissolve fro further refining.

Here are some links fro your studies:

We ask our new members to do 3 things.
1. Read C.M. Hokes book on refining jewelers scrap, it gives an easy introduction to the most important chemistry regarding refining.
It is free here on the forum: https://goldrefiningforum.com/phpBB3/viewtopic.php?f=54&t=19798
2. Then read the safety section of the forum: https://goldrefiningforum.com/forums/safety.47/
3. And then read about "Dealing with waste" in the forum: https://goldrefiningforum.com/threads/dealing-with-waste.10539/

Suggested reading:
https://goldrefiningforum.com/forums/the-library.101/
https://goldrefiningforum.com/threads/when-in-doubt-cement-it-out.30236/
https://goldrefiningforum.com/threa...le-read-this-before-you-post-about-ore.33333/


Forum rules is here.
https://goldrefiningforum.com/threads/gold-refining-forum-rules.31182/
 
Yggdrasil said:
Aah, I see now.
You want to remove the Manganese to drop Gold?
If there is a problem dropping the Gold, it is recommended to Cement on Copper, which will leave the Mn intact in solution.
Then collect the dropped Gold and redissolve fro further refining.

Here are some links fro your studies:

We ask our new members to do 3 things.
1. Read C.M. Hokes book on refining jewelers scrap, it gives an easy introduction to the most important chemistry regarding refining.
It is free here on the forum: https://goldrefiningforum.com/phpBB3/viewtopic.php?f=54&t=19798
2. Then read the safety section of the forum: https://goldrefiningforum.com/forums/safety.47/
3. And then read about "Dealing with waste" in the forum: https://goldrefiningforum.com/threads/dealing-with-waste.10539/

Suggested reading:
https://goldrefiningforum.com/forums/the-library.101/
https://goldrefiningforum.com/threads/when-in-doubt-cement-it-out.30236/
https://goldrefiningforum.com/threa...le-read-this-before-you-post-about-ore.33333/


Forum rules is here.
https://goldrefiningforum.com/threads/gold-refining-forum-rules.31182/
Click to expand...
That is it🤗..thank u so much for your support,i Will try...
Is there efective to precipitate Gold with PGM solution too?
 
Riyan said:
That is it🤗..thank u so much for your support,i Will try...
Is there efective to precipitate Gold with PGM solution too?
Click to expand...
Copper will only drop Gold and PGMs, and Mercury if there are.
Where is your material coming from?
Jewelry, e-waste or something else?
 
Riyan said:
That is it🤗..thank u so much for your support,i Will try...
Is there efective to precipitate Gold with PGM solution too?
Click to expand...

Yggdrasil said:
Copper will only drop Gold and PGMs, and Mercury if there are.
Where is your material coming from?
Jewelry, e-waste or something else?
Click to expand...

Riyan said:
I have proceed natural Gold ore
Click to expand...
With pretreatment HCL,then dillute in Aqua Regia, filtered well.When i add some SMB nothing happened,then i tray add NaCl03 in to hot solution.this is the results;is there Palladium?
 

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Riyan said:
I m so sorry,i don't have it
Click to expand...
So what is it?
Do you have an assay or not?

So you are quite bold then, dissolving unknown substances in acids!
There are many substances that may harm or even kill you in rocks.

Ores are rarely treated with acids, and never unless you have a proper assay.
And there is more than one reason for that.

Stannous is easy to make, just dissolve some Tin in HCl.

How do you know you have Gold in the rocks if you have no test showing it?

Here, read this whole thread, thoroughly!

https://goldrefiningforum.com/threa...s-before-you-post-about-ore.33333/post-356302

Edit: Replaced link with the correct one.
 
Last edited:
Riyan said:
I don't have stannous solution test
Click to expand...
Riyan said:
With pretreatment HCL,then dillute in Aqua Regia, filtered well.When i add some SMB nothing happened,then i tray add NaCl03 in to hot solution.this is the results;is there Palladium?
Click to expand...

Riyan said:
With pretreatment HCL,then dillute in Aqua Regia, filtered well.When i add some SMB nothing happened,then i tray add NaCl03 in to hot solution.this is the results;is there Palladium?
Click to expand...
The second picture is
sediment roasted
 
Yggdrasil said:
So what is it?
Do you have an assay or not?

So you are quite bold then, dissolving unknown substances in acids!
There are many substances that may harm or even kill you in rocks.

Ores are rarely treated with acids, and never unless you have a proper assay.
And there is more than one reason for that.

Stannous is easy to make, just dissolve some Tin in HCl.

How do you know you have Gold in the rocks if you have no test showing it?

Here, read this whole thread, thoroughly!

https://goldrefiningforum.com/threa...s-before-you-post-about-ore.32137/post-341903
Click to expand...
Other people get some gold placer ,then i try to treath rocks with chemichal
 

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