Aqua Regia Digest 500 g material.

[Aled]

Greetings everyone.

I did start another Aqua Regia digest on 500 g of a placer materialsmagnetically separated Black sands that still had some very fine gold trapped in the black sands concentrate . And I left the leach solution standing for two days on very low heat.

Using the same methods of HCL solution with the addition of HNO3 to create an Aqua Regis solution.

I used the standard boiling down protocol to remove the nitrates by adding a little bit of HCL and water to bulk up the solution. A lot of nitric fumes on the first boil of the solution.

As I was adding more hot water to the solution to bulk it up gold is present as my gloves turned purple in the process. And following the Stannous Chloride test gold present.

Let the solution stand over night.

A red precipitate formed in the solution.

I filtered and removed the red precipitate.

To be examined later.

What could this possibly be.?

Re Filtered the solution three times to make sure the solution was clean and clear of any solids.

Placed this in the Hot plate just to get it back to a warm state.

Started adding Sodium Metabisulfite and I mean plenty.

The solution went through various color stages,

The solution did start fizzing and I placed this in much larger beaker.

Ph is now 1.4 and bulk this solution with water to 2 litres in total just to give it room.

Nothing is dropping out of solution this time.?

I will add some pictures of the color of the solution.

I will let this sit till tomorrow give it time for anything to drop out of solution.

Any input would be greatly appreciated.

Thank you kindly. Avled.

#1 Picture Au on the glove. Some Au was lost.?
#2 AR Boiling down to remove Nitrates.
#3 Removing Nitrates
#4 Red brown precipitate formed overnight while solution was cooling down. Filtered the solution to remove Red brown precipitate.
#5 Placed solution in larger beaker and started adding SMB different color changes light brown.
#6 Solution slightly green.
#7 Solution light green and this is where i left it for the moment.

 

[Yggdrasil]

Greetings everyone.

I did start another Aqua Regia digest on 500 g of a placer materialsmagnetically separated Black sands that still had some very fine gold trapped in the black sands concentrate . And I left the leach solution standing for two days on very low heat.

Using the same methods of HCL solution with the addition of HNO3 to create an Aqua Regis solution.

I used the standard boiling down protocol to remove the nitrates by adding a little bit of HCL and water to bulk up the solution. A lot of nitric fumes on the first boil of the solution.

As I was adding more hot water to the solution to bulk it up gold is present as my gloves turned purple in the process. And following the Stannous Chloride test gold present.

Let the solution stand over night.

A red precipitate formed in the solution.

I filtered and removed the red precipitate.

To be examined later.

What could this possibly be.?

Re Filtered the solution three times to make sure the solution was clean and clear of any solids.

Placed this in the Hot plate just to get it back to a warm state.

Started adding Sodium Metabisulfite and I mean plenty.

The solution went through various color stages,

The solution did start fizzing and I placed this in much larger beaker.

Ph is now 1.4 and bulk this solution with water to 2 litres in total just to give it room.

Nothing is dropping out of solution this time.?

I will add some pictures of the color of the solution.

I will let this sit till tomorrow give it time for anything to drop out of solution.

Any input would be greatly appreciated.

Thank you kindly. Avled.

#1 Picture Au on the glove. Some Au was lost.?
#2 AR Boiling down to remove Nitrates.
#3 Removing Nitrates
#4 Red brown precipitate formed overnight while solution was cooling down. Filtered the solution to remove Red brown precipitate.
#5 Placed solution in larger beaker and started adding SMB different color changes light brown.
#6 Solution slightly green.
#7 Solution light green and this is where i left it for the moment.

First of all, do you have a proper assay?
Are you sure there are no Cadmium, Arsenic or Mercury in there?

How did you make your AR?
Premixing?
Noting other other than Silver Chloride should precipitate out.
Was there material left in solution when the digest was done?

If you use the evaporation route you are supposed to evaporate down to a thick syrupy consistency (Not dry) and Not Boil.
Then add enough HCl to make it liquid again.
Then redo the procedure until no more fumes comes when adding the HCl.

After this is done you can add enough ice cubes and water to increase the volume by 2-3 and filter it well.
This solution will be yellowish to reddish with green depending on the metals in there.

Add your SMB in appr 1:1 with respect to expected Gold content.

Have you read Hokes book?

 

[Aled]

Greetings Yddrasil.

Thank you for getting back to me.
An assay is being done at another facility. I should have more details in a short time to come. Yes I do suspect some Cadmium, Arsenic or Mercury in the material.

I did not premix the AR. I started of with placing the material in the HCL solution and slowly adding some HNO3 to the HCL. Close to three to one ratio.

After the leaching of the materials was completed there was still material left in the solution.
I removed the pulp material by filtration and washing the material so that the solution was free and clear of any solids.

I did boil the solution turning down the heat as i was getting close to down to a thick syrupy consistency it was never dry. Only ting i did was boil and not evaporate. I Will keep that in mind on my next leach.
I did add enough HCl to make it liquid again plus some distilled water to bring the volume up again total three times..
No more fumes where showing when i was adding the HCl.

I did not add any ice cubes i left the volume of the solution same level as what i started of with. I let this sit overnight and that is when the red brown precipitate appeared.
In future i will add the ice and increase the volume and filter immediately. Until crystal clear.

And i will add the SMB in these ratios as well.

I am reading the Hokes book as well. In order to gain better understanding.
So i can figure out my next steps with the solution that i have right now.

Maybe i will to a metal exchange cementation with Zinc? Just a thought.

Thank you kindly for your input.
Much appreciated.

 

[Martijn]

Greetings everyone.

I did start another Aqua Regia digest on 500 g of a placer materialsmagnetically separated Black sands that still had some very fine gold trapped in the black sands concentrate . And I left the leach solution standing for two days on very low heat.

Using the same methods of HCL solution with the addition of HNO3 to create an Aqua Regis solution.

I used the standard boiling down protocol to remove the nitrates by adding a little bit of HCL and water to bulk up the solution. A lot of nitric fumes on the first boil of the solution.

As I was adding more hot water to the solution to bulk it up gold is present as my gloves turned purple in the process. And following the Stannous Chloride test gold present.

Let the solution stand over night.

A red precipitate formed in the solution.

I filtered and removed the red precipitate.

To be examined later.

What could this possibly be.?

Re Filtered the solution three times to make sure the solution was clean and clear of any solids.

Placed this in the Hot plate just to get it back to a warm state.

Started adding Sodium Metabisulfite and I mean plenty.

The solution went through various color stages,

The solution did start fizzing and I placed this in much larger beaker.

Ph is now 1.4 and bulk this solution with water to 2 litres in total just to give it room.

Nothing is dropping out of solution this time.?

I will add some pictures of the color of the solution.

I will let this sit till tomorrow give it time for anything to drop out of solution.

Any input would be greatly appreciated.

Thank you kindly. Avled.

#1 Picture Au on the glove. Some Au was lost.?
#2 AR Boiling down to remove Nitrates.
#3 Removing Nitrates
#4 Red brown precipitate formed overnight while solution was cooling down. Filtered the solution to remove Red brown precipitate.
#5 Placed solution in larger beaker and started adding SMB different color changes light brown.
#6 Solution slightly green.
#7 Solution light green and this is where i left it for the moment.

https://goldrefiningforum.com/threads/when-in-doubt-cement-it-out.30236/Did you try the leach base metals from the black sands before going for Aqua Regia?
How much of everything was added to the mix?

 

[Aled]

Greetings Martijn
Thank you for getting back to me.
I did not leach any of the base metals prior to the AR leach.
I used 500 g material.
300 ml HCl and once the material was added to the HCl then I started to add the HNO3 close to 100ml.
Hope this answers your question.

 

[Aled]

https://goldrefiningforum.com/threads/when-in-doubt-cement-it-out.30236/Did you try the leach base metals from the black sands before going for Aqua Regia?
How much of everything was added to the mix?

Greetings Martijn.
Could you please give me some sugestions regarding removal of the base metals prior to the Aqua Regia leach. And yes I am reviewing the Hoke Book once more.
What other type of leaches could one perform?
Hydroxide, Sulfuric...
Your input is greatly appreciated.
Or anyone else on the board has any ideas. Or which treads on the board I can go review.
Kind regards Avled.

 

[Yggdrasil]

Greetings Martijn.
Could you please give me some sugestions regarding removal of the base metals prior to the Aqua Regia leach. And yes I am reviewing the Hoke Book once more.
What other type of leaches could one perform?
Hydroxide, Sulfuric...
Your input is greatly appreciated.
Or anyone else on the board has any ideas. Or which treads on the board I can go review.
Kind regards Avled.

It is always recommended to remove all or as much as possible of base metals before you dissolve any Gold.
If not, what ever Gold you dissolve will cement out on the base metals at least some of it.
The exception is targeted leaches like Cyanides and such for ores.

 

[Aled]

Thank you for your input Yggdrasil.
I will be looking into this a lot more. Removal of the base metals prior to Aqua Regia leach.
Have a great day.

 

[Martijn]

Greetings Martijn.
Could you please give me some sugestions regarding removal of the base metals prior to the Aqua Regia leach. And yes I am reviewing the Hoke Book once more.
What other type of leaches could one perform?
Hydroxide, Sulfuric...
Your input is greatly appreciated.
Or anyone else on the board has any ideas. Or which treads on the board I can go review.
Kind regards Avled.

I think HCl will at least remove iron and other base metals. Since you have leached with AR and are still breathing there are no nasty things in there ore you were just lucky.
A nitric leach should remove any other base metal HCl did not get.
But did you roast and grind and reroast the black sands? And separated anythingcwith a magnet?

 

[Aled]

Greetings Martijn
Thank you for getting back to me.
Just to inform you I work in a safe environment and being aware of some of the nasties that would present themselves. I work under a fume hood as well. And take all necassary safety measures into account. But thank you for pointing this out.
The materials have been roasted and pulverized.
My next batch of the Magnetically separated black sands i will do the following.
Pretreatment of the ore.
Pulverize materials.
Roast materials.
I will treat the ore in an HCl solution to remove any Iron base metals.
I will then filter and wash the material.
Then treat the material with an Nitric solution to remove any other base metals.
Again after this filter and wash.
There is still very fine micron gold stuck with the black sands so I did not remove any more black sands.
And I will roast again.
After these treatments I will then proceed with and AR leach.
Hopefully improving some of the recoveries.

I did recover a small bead from the previous leach.

Thank you and have a great day.

.

 

[Aled]

Greetings to the Forum.
Just wanted to give you a brief update and see what other input advice can be given.
I have continued doing the AR leaches on the black sand nugget trap materials upon which most of the free gold has been removed and targeting any micron gold.
Following the advice and steps given by the group.
Plus reading the C-M Hoke book and finding many hidden treasures and applications. And reading a multitude of other treads from the group to gain a much deeper understanding.


I worked on 50 g samples yes they are small but I wanted to see and experience the different reactions and precipitates that evolved from this.

Pictures will be included.

And any further advice or direction comments is always appreciated.


This sample was pulverized with the Disk pulverizer just to give more surface area and liberate more values within the material.
As mentioned in this tread before remove the base metals prior to the Aqua Regia Leach.
The material does contain a very small amount of Au.
This was tested by Fire Assay and having done the Stannous chloride test on previous leaches.


I pretreated the material in a HNO3 leach overnight 30 C.
The next day filtered and washed the material.
Proceeded to do the AR leach.
HCL first and slowly adding HNO3 just enough to have the reactions going.
Again I left this overnight on low heat 30 C.
This was filtered and the solids recovered.
Added an equal volume of water and heated this to 85 C.
Added Sulfamic acid fizzing and slight foaming reaction.
Since I am new to using Sulfamic acid as I used to evaporate three times in the past to a syrup and adding HCL to remove nitrates.
Did not know what to expect with the Sulfamic acid and how far to go.
But I stopped till there where no more reactions.
I then started adding the SMB to the warm solution. But nothing precipitated out of the solution.
I decided to evaporate the solution to a syrup just to make sure all of the nitrates were removed.
And I did not see any Nitrates. Working under the fume hood.
But a crust was forming on top of the syrupy solution which disappeared once I slowly started increasing the volume of the solution with HCL.
Added more water and doubled the volume.
I added a copper plate to cement out any of the values. After a few hours a very very tiny amount of black precipitate.
I did the stannous chloride test prior and a very small trace of gold showed. Nothing to significant.
As the chloride solution cooled white crystals formed on the bottom of the beaker. And I was wondering what this could be. And how to proceed any further.

Any suggestions are welcome.

I have done the same test to remove the base metals but this time first using HCL overnight low temperature. Filtered washed and roasted as to remove any possible chloride that might be left in the solution. And then proceed with HNO3 overnight. Again filtered and washed before I proceeded with the Aqua regia digest.
Thist is still AR leaching for the moment.

Knowing this is a long tread just wanted make sure I did not leave out any details and to describe a clear picture.

Again much appreciate any input. And also happy if anyone else gains anything from this.

Regards Avled.

 

[Yggdrasil]

Greetings to the Forum.
Just wanted to give you a brief update and see what other input advice can be given.
I have continued doing the AR leaches on the black sand nugget trap materials upon which most of the free gold has been removed and targeting any micron gold.
Following the advice and steps given by the group.
Plus reading the C-M Hoke book and finding many hidden treasures and applications. And reading a multitude of other treads from the group to gain a much deeper understanding.


I worked on 50 g samples yes they are small but I wanted to see and experience the different reactions and precipitates that evolved from this.

Pictures will be included.

And any further advice or direction comments is always appreciated.


This sample was pulverized with the Disk pulverizer just to give more surface area and liberate more values within the material.
As mentioned in this tread before remove the base metals prior to the Aqua Regia Leach.
The material does contain a very small amount of Au.
This was tested by Fire Assay and having done the Stannous chloride test on previous leaches.


I pretreated the material in a HNO3 leach overnight 30 C.
The next day filtered and washed the material.
Proceeded to do the AR leach.
HCL first and slowly adding HNO3 just enough to have the reactions going.
Again I left this overnight on low heat 30 C.
This was filtered and the solids recovered.
Added an equal volume of water and heated this to 85 C.
Added Sulfamic acid fizzing and slight foaming reaction.
Since I am new to using Sulfamic acid as I used to evaporate three times in the past to a syrup and adding HCL to remove nitrates.
Did not know what to expect with the Sulfamic acid and how far to go.
But I stopped till there where no more reactions.
I then started adding the SMB to the warm solution. But nothing precipitated out of the solution.
I decided to evaporate the solution to a syrup just to make sure all of the nitrates were removed.
And I did not see any Nitrates. Working under the fume hood.
But a crust was forming on top of the syrupy solution which disappeared once I slowly started increasing the volume of the solution with HCL.
Added more water and doubled the volume.
I added a copper plate to cement out any of the values. After a few hours a very very tiny amount of black precipitate.
I did the stannous chloride test prior and a very small trace of gold showed. Nothing to significant.
As the chloride solution cooled white crystals formed on the bottom of the beaker. And I was wondering what this could be. And how to proceed any further.

Any suggestions are welcome.

I have done the same test to remove the base metals but this time first using HCL overnight low temperature. Filtered washed and roasted as to remove any possible chloride that might be left in the solution. And then proceed with HNO3 overnight. Again filtered and washed before I proceeded with the Aqua regia digest.
Thist is still AR leaching for the moment.

Knowing this is a long tread just wanted make sure I did not leave out any details and to describe a clear picture.

Again much appreciate any input. And also happy if anyone else gains anything from this.

Regards Avled.

I would have done the Stannous before filtering.
How many ml did you have before adding the SMB?

From 50g of potential Gold bearing material I would not expect to see anything precipitating,
I'd expect the Gold to be in the microgram range if any, and that will not be visible.
Do you have picture of your Stannous test?

 

[Aled]

Greetings Yggdrasil.
A pleasure hearing back from you.
I did the Stannous chloride test prior to filtering here is a picture of the small amount of Au that is in solution.
Yes the Au would be in the microgram range.
Reasons for testing smaller amounts so that i do not have to waste large amounts of Chemicals but to observe the other reactions and see what does drop out of solution.
And to observe what happens when the base metals are removed. Before I scale this up to a larger sample.
The biggest question I have is should i just pretreat the materials first with HNO3 or just go with HCL first.
Or Do HCL first and then go with HNO3.
Or what effect would the Sulfuric Acid have on the base metals. But i do not want to get to far ahead of myself here.
From past experience with different ore sample is that they are all unique in their own way and it takes time to deal with and to come up with the right pre treatment protocols. In order to extract the most values.
Any further input is always much appreciated.
And i could not answer you sooner. Got busy with things.
Regards Avled.

 

[Yggdrasil]

Greetings Yggdrasil.
A pleasure hearing back from you.
I did the Stannous chloride test prior to filtering here is a picture of the small amount of Au that is in solution.
Yes the Au would be in the microgram range.
Reasons for testing smaller amounts so that i do not have to waste large amounts of Chemicals but to observe the other reactions and see what does drop out of solution.
And to observe what happens when the base metals are removed. Before I scale this up to a larger sample.
The biggest question I have is should i just pretreat the materials first with HNO3 or just go with HCL first.
Or Do HCL first and then go with HNO3.
Or what effect would the Sulfuric Acid have on the base metals. But i do not want to get to far ahead of myself here.
From past experience with different ore sample is that they are all unique in their own way and it takes time to deal with and to come up with the right pre treatment protocols. In order to extract the most values.
Any further input is always much appreciated.
And i could not answer you sooner. Got busy with things.
Regards Avled.

The stannous test look good.
What do your assay say?

Here is a method posted by Ultrax in another thread:
https://goldrefiningforum.com/threa...-or-if-its-just-pyrite-help.33802/post-363032

 

[Aled]

Greetings Yggdrasil.
The assays shows good recovery of Au.
15 Opt. Depending on the concentration levels. But Au is there. Beautiful beads.
Thank you Kindly.

 

[Aled]

Question to the group.
If you read my previous posts on the steps that i have taken regarding the AR Leach.
After i added the Sulfamic Acid until there was no more foaming Nitrates removed. I added SMB nothing dropped out of solution. I let the solution stand for two day and a white crystalline salt precipitated out of solution. Does any one have any idea as to what I might be looking at. Did i maybe add to much Sulfamic acid to the solution and it precipitated out after cooling the solution.
Hope to hear a few possibilities.
Thank you and have a great day.
Pictures to follow.

 

[Yggdrasil]

Question to the group.
If you read my previous posts on the steps that i have taken regarding the AR Leach.
After i added the Sulfamic Acid until there was no more foaming Nitrates removed. I added SMB nothing dropped out of solution. I let the solution stand for two day and a white crystalline salt precipitated out of solution. Does any one have any idea as to what I might be looking at. Did i maybe add to much Sulfamic acid to the solution and it precipitated out after cooling the solution.
Hope to hear a few possibilities.
Thank you and have a great day.
Pictures to follow.

What did the Stannous say?

 

[Aled]

The Stannous still showed a weak color of Au. Lesser to the the picture shown previously.
Thank you Yggdrasil.

 

[Yggdrasil]

Question to the group.
If you read my previous posts on the steps that i have taken regarding the AR Leach.
After i added the Sulfamic Acid until there was no more foaming Nitrates removed. I added SMB nothing dropped out of solution. I let the solution stand for two day and a white crystalline salt precipitated out of solution. Does any one have any idea as to what I might be looking at. Did i maybe add to much Sulfamic acid to the solution and it precipitated out after cooling the solution.
Hope to hear a few possibilities.
Thank you and have a great day.
Pictures to follow.

How much solution did you have?
How much Nitric did you use?
How much Sulfamic did you use and at which temperature.
How much SMB did you use and what was the pH?

 

[Aled]

Greetings Yggdrasil
Thank you for getting back to me.
Here are the answer to the questions you have as outlined part and partial in the previous posts.
30 g material.
Total volume of the AR leach solution.
200 ml.
Total HNO3 is 50 ml.
Total sulfamic 20g temperature 80C.
Total SMB 10 g and the 0.8 ph.
Regards Avled