nitric solution too thick for filtration....

[nickvc]

Looking at what you are working with its quite possible that some was simply plated and maybe some karat items, if it's plated that could well be your problem as they plate a myriad of alloys.
I would be tempted to filter your solution and the powder and any solids off, rinse well several times put them back into a beaker and try some dilute sulphuric with gentle heat, if that fails to remove the powder then rinse off the sulphuric and try some HCl, if that was all you started with then unless there was some karat material you are not looking at a lot of gold but be sure to test your solutions before safe disposal.

 

[g_axelsson]

I always use hydrochloric acid with iron and iron oxide.
Fe2O3 + 6HCL -> 2FeCl3 + 3H2O
as you say settle and take off the liquor,but then may be wash and settle again.
Then try a hydrochloric leach?
Try a sample each way before you make a decision.

That could end up dissolving the gold, unless he incinerates between the nitric leach/rinse and the hcl leach. If there is enough iron (or very little hcl) it would precipitate the gold back out via cementation, but since he is already doing a nitric leach, continuing it would be the quickest.

Though, I have had pretty good luck with using a dilute sulfuric leach after the initial nitric run. After the iron is gone, assuming more base metal exists, I do another nitric bath before going to ar, just to be certain all the base metal junk is eliminated.

I do not think there is much chance of getting any gold into solution while there is so much base metals present. Though you may put it into solution and instantly cement it as fine deposition.
As you will have to rely on settling instead of filtering that should not be too much of an issue.
You can see the remains of a ring poking out.
The sediment should wash off the remaining metal so you can see what is left.
Fine particle should be settled out.
if the nitric leach has produced such an adverse reaction ,stop and test all alternatives before you try and make a decision.
He has the gunk so only he can test which rout is best.

I can't see any base metals left. Rust isn't base metal, it's a compound and would not cement any gold from a solution.

I haven't worked with gold filled yet but many times with tricky sediments...

If this was gold filled, wouldn't the karat gold be sitting on the bottom as small flakes and pieces? If so, the red silt could be washed away before it settle and with a couple of washes most of it could be separated from undissolved base metal and gold pieces. The silt and any fine gold particles can then be processed away from the major part of the gold.
It is better to have as little gold in with the problem material as possible.

Göran

 

[Justincase]

I always use hydrochloric acid with iron and iron oxide.
Fe2O3 + 6HCL -> 2FeCl3 + 3H2O
as you say settle and take off the liquor,but then may be wash and settle again.
Then try a hydrochloric leach?
Try a sample each way before you make a decision.

That could end up dissolving the gold, unless he incinerates between the nitric leach/rinse and the hcl leach. If there is enough iron (or very little hcl) it would precipitate the gold back out via cementation, but since he is already doing a nitric leach, continuing it would be the quickest.

Though, I have had pretty good luck with using a dilute sulfuric leach after the initial nitric run. After the iron is gone, assuming more base metal exists, I do another nitric bath before going to ar, just to be certain all the base metal junk is eliminated.

I do not think there is much chance of getting any gold into solution while there is so much base metals present. Though you may put it into solution and instantly cement it as fine deposition.
As you will have to rely on settling instead of filtering that should not be too much of an issue.
You can see the remains of a ring poking out.
The sediment should wash off the remaining metal so you can see what is left.
Fine particle should be settled out.
if the nitric leach has produced such an adverse reaction ,stop and test all alternatives before you try and make a decision.
He has the gunk so only he can test which rout is best.

I can't see any base metals left. Rust isn't base metal, it's a compound and would not cement any gold from a solution.

I haven't worked with gold filled yet but many times with tricky sediments...

If this was gold filled, wouldn't the karat gold be sitting on the bottom as small flakes and pieces? If so, the red silt could be washed away before it settle and with a couple of washes most of it could be separated from undissolved base metal and gold pieces. The silt and any fine gold particles can then be processed away from the major part of the gold.
It is better to have as little gold in with the problem material as possible.

Göran

Bottom picture of a beaker. you can see a ring or some other curved bit of metal sticking out.
Let us see if there are any undigested metals .

 

[Topher_osAUrus]

Goldfilled doesnt always end up in solid foils, only if you're lucky.
Rarely though, since it is usually heavily worn in some spots. So there will be foils, but there will be tons of little flakes too.
So just dumping it off, is dumping off a good bit of your gold.

 

[g_axelsson]

Little flakes should sink quite fast too. I have separated gold plate from stannous sludge at times.

I just suggested to split the lot in a easy and a hard part, not dumping it off... unless the hard part doesn't contain enough gold to warrant the extra work and chemical expenses.

Göran

 

[Topher_osAUrus]

True that. The flakes do usually sink fast, but there are always those odd bits that dont. ..Or the pieces of clasp that have air pockets in them so they float forever.

I think I would try to take a small sample of the red motor oil looking nitric, and add just a couple mL of sulfuric. See if it gets all the oxidized iron to go into solution and clear up a bit. That way he can see whats really going on.

I know I would definitely try to fish that "24k" chain out of the mix, so it can't keep causing issues.

 

[fyatim]

If i had to guess iron! The green of the nitric tell me and the rust to go along with it!
Add more nitric and heat until completion. I think what you will find out is the items are plated and not filled and they are on a cheap iron magnetic base. Yield will be low!

Following Palladium's suggestion and valuable remark from modtheworld44 "Iron falls out of nitric when it is diluted", I proceeded as follows:
- Left the beaker containing the staff to settle and evaporate on mid heat for about 24H.
- Then, added about 200ml nitric acid while the beaker is on heat. Acid added in small quantities during about 24H.
I end up with some gold foils and some dark powder in the solution without any trace of the red sludge shown in the photos. I attach a new photo of the resulting solution.
Possible conclusions:
- My GF contains Iron (I bleive in the pieces marked 24K and 10k balls)
- After processing with normally diluted nitric acid and heat, No red sludge was observed.
- Only after adding quantity of water and ice cubes to cool down before filtering, the Red sludge appears as shown in the picture.
I will continue processing the batch:
- Filtering and rinsing with water
- Rinsing with hcl
- Treatment with AR

 

[g_axelsson]

- Only after adding quantity of water and ice cubes to cool down before filtering, the Red sludge appears as shown in the picture.

This is a leading question, I want you to think and motivate why you cool down and dilute the solution before filtering. What are you trying to accomplice and what are the results of your actions?

I will continue processing the batch:
- Filtering and rinsing with water
- Rinsing with hcl
- Treatment with AR

What is going to happen at step "-Rinsing with hcl"?
I would advise you to think about it for a while and not do it.

Göran

 

[nickvc]

- Only after adding quantity of water and ice cubes to cool down before filtering, the Red sludge appears as shown in the picture.

This is a leading question, I want you to think and motivate why you cool down and dilute the solution before filtering. What are you trying to accomplice and what are the results of your actions?

I will continue processing the batch:
- Filtering and rinsing with water
- Rinsing with hcl
- Treatment with AR

What is going to happen at step "-Rinsing with hcl"?
I would advise you to think about it for a while and not do it.

Göran

This could be a case of a little knowledge been a dangerous thing....
Take Gorans advice and step back and read some more about what you are trying to achieve.

 

[fyatim]

- Only after adding quantity of water and ice cubes to cool down before filtering, the Red sludge appears as shown in the picture.

This is a leading question, I want you to think and motivate why you cool down and dilute the solution before filtering. What are you trying to accomplice and what are the results of your actions?

I will continue processing the batch:
- Filtering and rinsing with water
- Rinsing with hcl
- Treatment with AR

What is going to happen at step "-Rinsing with hcl"?
I would advise you to think about it for a while and not do it.

Göran

This could be a case of a little knowledge been a dangerous thing....
Take Gorans advice and step back and read some more about what you are trying to achieve.

Thank you for your advice, but please try to be more direct. I do not see what is your issues!!
I added water to cool the solution and facilitate the filtering process. Now, I learned that this will precipitate any Iron present in the nitric acid solution. What else?
After washing with water the content of my filter, I plan to wash with HCl to clean any residuals, what is again the issue?
Please, explain your point of view or direct me to a specific reading. Do not just say " step back and read some more about what you are trying to achieve". I m a beginner, I know, and you are experts. Tha's why I m a member of this forum... To get direct advice and help when possible.

 

[nickvc]

- Only after adding quantity of water and ice cubes to cool down before filtering, the Red sludge appears as shown in the picture.

This is a leading question, I want you to think and motivate why you cool down and dilute the solution before filtering. What are you trying to accomplice and what are the results of your actions?

I will continue processing the batch:
- Filtering and rinsing with water
- Rinsing with hcl
- Treatment with AR

What is going to happen at step "-Rinsing with hcl"?
I would advise you to think about it for a while and not do it.

Göran

This could be a case of a little knowledge been a dangerous thing....
Take Gorans advice and step back and read some more about what you are trying to achieve.

Thank you for your advice, but please try to be more direct. I do not see what is your issues!!
I added water to cool the solution and facilitate the filtering process. Now, I learned that this will precipitate any Iron present in the nitric acid solution. What else?

You have removed the iron only to precipitate it again, this is pointless, you should have either carefully poured the solution off or symphonies it so you had very little to no iron to worry about.

After washing with water the content of my filter, I plan to wash with HCl to clean any residuals, what is again the issue?

Without incinerating the material you will create AR which can and will dissolve some of your gold, you cannot remove all the nitric with just rinsing .

Please, explain your point of view or direct me to a specific reading. Do not just say " step back and read some more about what you are trying to achieve". I m a beginner, I know, and you are experts. Tha's why I m a member of this forum... To get direct advice and help when possible.

I accept you are new and english probably isn't your first language but you need to read Hoke and some of the threads here on the forum to gain a basic understanding in what you want to achieve, not wanting to be rude but you will make a very large mess that can take a lot more understanding to recover from, I cannot sugar coat my reply as the study and reading are essential if you want to be successful not just in this but in any future processing, we can't make you understand the reactions and processes without some basic knowledge from you.

 

[modtheworld44]

- Only after adding quantity of water and ice cubes to cool down before filtering, the Red sludge appears as shown in the picture.

This is a leading question, I want you to think and motivate why you cool down and dilute the solution before filtering. What are you trying to accomplice and what are the results of your actions?

I will continue processing the batch:
- Filtering and rinsing with water
- Rinsing with hcl
- Treatment with AR

What is going to happen at step "-Rinsing with hcl"?
I would advise you to think about it for a while and not do it.

Göran

This could be a case of a little knowledge been a dangerous thing....
Take Gorans advice and step back and read some more about what you are trying to achieve.

Thank you for your advice, but please try to be more direct. I do not see what is your issues!!
I added water to cool the solution and facilitate the filtering process. Now, I learned that this will precipitate any Iron present in the nitric acid solution. What else?
After washing with water the content of my filter, I plan to wash with HCl to clean any residuals, what is again the issue?
Please, explain your point of view or direct me to a specific reading. Do not just say " step back and read some more about what you are trying to achieve". I m a beginner, I know, and you are experts. Tha's why I m a member of this forum... To get direct advice and help when possible.

If this was my materials,this is what I would do.

I would filter(without the use of water) then go straight to AR.
I would add small milliliter additions of nitric until everything was dissolved.
I would de-nox and then refilter and then drop the gold out with SMB.
Then wash powders in boiling distilled water and then simmering HCL.
Then see if the powders had a color change and do this until I see color change.
Then I would melt the powders into a nice shiny button.
Thanks in advance.



modtheworld44

 

[fyatim]

Following on my case (of Red sludge in nitric acid solution), here is a picture of the result after washing the filtered foils with distilled water and treatment with AR. The other picture is the positive test with stannous chloride.
Please note that I skipped the HCl washing step to avoid the risk of having nitric acid particles not cleaned after water washing (this was the point of nickvc and goran I think).
Also, notice the very small amount of gold as predicted by Palladium;

 

[fyatim]

If this was my materials,this is what I would do.

I would filter(without the use of water) then go straight to AR.
I would add small milliliter additions of nitric until everything was dissolved.
I would de-nox and then refilter and then drop the gold out with SMB.
Then wash powders in boiling distilled water and then simmering HCL.
Then see if the powders had a color change and do this until I see color change.
Then I would melt the powders into a nice shiny button.
Thanks in advance.
modtheworld44

You are right. I have filtered the materials without water, but after the filtering is done, I start adding water into the filter. The solution down the filter was re-contaminated with the re-precipitation of iron, but the filtered materials in the filter were clear.
I did not add any nitric acid in the filter, but I could have done that to be sure (you are right);
What do you mean by de-nox? I do not know this term...
For the gold precipitation and melting, I will do it later with other batches as this one is very small...

I would like to thank all of you for your interest and support.
The return in gold is nothing, but the return in knowledge was very important for me during those few days.

 

[FrugalRefiner]

What do you mean by de-nox? I do not know this term...

See A Glossary of Common Terms.

Dave

 

[g_axelsson]

By finding out why washing the filter in HCl you learned it and will remember it next time.
If I had told you why you would have forgotten about it in a few days.

The forum helps those that show they put some effort in doing the research themselves.

Göran

 

[fyatim]

What do you mean by de-nox? I do not know this term...

See A Glossary of Common Terms.

Dave

Thank you, Dave, for this valuable glossary.
Regards

 

[fyatim]

By finding out why washing the filter in HCl you learned it and will remember it next time.
If I had told you why you would have forgotten about it in a few days.

The forum helps those that show they put some effort in doing the research themselves.

Göran

Yes, you are absolute right Goran. But, you know, when we are under pressure of the situation and looking to understand what is happening it becomes frustrating to hear general advice instead of specific action.
Please be assured that my first experience with the forum is very rich and I will stay in contact with you for my next fun experiences.
regards

 

[Topher_osAUrus]

So the forum is only good to come to when you are in the thick of it? -no pun intended on your first nitric run...

 

[FrugalRefiner]

So the forum is only good to come to when you are in the thick of it? -no pun intended on your first nitric run...

I didn't take his comment that way. I understood him to be saying that he was under the gun on this batch, so he didn't have as much time to search out the answer in this case. I could be wrong, but I always try to give everyone the benefit of the doubt.

Dave