PGM Help

[MindyBeatty]

Hello everyone! I was wondering if I could get some assistance in my recovery from ore.

I started with the normal aqua regia and let leach. When it was finished I neutralized the nitric and filtered. I then raised the pH with sodium hydroxide and turned all base metals into hydroxide form and filtered them out. I then added dilute hcl to bring the pH back down and dropped in zinc. I recovered a dark gray to black powder (pic 1 and 2.) My solution was clear but I had a feeling it wasn't emptied of the metals, so I added a drop of peroxide to my now clear solution and sure enough it went yellow. Something didn't cement with the zinc. Long story short,I finally dropped it with vitamin c and got another dark powder this time though it had a reddish undertone to it. I decided to recover with electrolysis and a dark metallic silver metal is plating. Does anyone know what pgm(s) I'm dealing with?

 

[Yggdrasil]

Hello everyone! I was wondering if I could get some assistance in my recovery from ore.

I started with the normal aqua regia and let leach. When it was finished I neutralized the nitric and filtered. I then raised the pH with sodium hydroxide and turned all base metals into hydroxide form and filtered them out. I then added dilute hcl to bring the pH back down and dropped in zinc. I recovered a dark gray to black powder (pic 1 and 2.) My solution was clear but I had a feeling it wasn't emptied of the metals, so I added a drop of peroxide to my now clear solution and sure enough it went yellow. Something didn't cement with the zinc. Long story short,I finally dropped it with vitamin c and got another dark powder this time though it had a reddish undertone to it. I decided to recover with electrolysis and a dark metallic silver metal is plating. Does anyone know what pgm(s) I'm dealing with?

First off.
Leaching ores can be really dangerous if you do not have full control of what is in there.

Do you have a proper assay?

Next there is a lot of misunderstanding regarding Nitric as many call deNOxing for neutralizing.
This do not matter much as you have seriously neutralized it.
Why did you do that?
Did you find some procedure that works like that?
What was the pH when you were done adding NaOH?

Some base metals and even all the Silver, Gold, Palladium and what not will have dropped as Hydroxides.
The only one that not readily form Hydroxides is Platinum.

Then you used Zinc which will drop all metals in stead of using Copper.
Hydrogen Peroxide will not drop anything, but in HCl it will dissolve Gold and much more if it is finely divided.

 

[Martijn]

If you olny used nitric to dissolve metals, it can be anything soluble in nitric and less reactive than zinc.
If you want to cement out precious metals dissolved in nitric, which are silver and palladium, using copper to cement the values out will leave non precious metals in solution.
Look at the reactivity series to learn this, along with the thread 'dealing with waste'
https://goldrefiningforum.com/threads/dealing-with-waste.10539/
https://en.wikipedia.org/wiki/Reactivity_series

 

[Martijn]

Usually I'm all about safety, but yes, what Yggdrasil said.

 

[Yggdrasil]

If you olny used nitric to dissolve metals, it can be anything soluble in nitric and less reactive than zinc.
If you want to cement out precious metals dissolved in nitric, which are silver and palladium, using copper to cement the values out will leave non precious metals in solution.
Look at the reactivity series to learn this, along with the thread 'dealing with waste'
https://goldrefiningforum.com/threads/dealing-with-waste.10539/
https://en.wikipedia.org/wiki/Reactivity_series

She said she used AR so everything excluding Iridium can be there, as we have not seen the assay yet.

 

[MindyBeatty]

I don't have an assay. I wasn't asking about my procedure, I am asking if anyone knows how to identify the powder I got by the provided pictures.

 

[Martijn]

She said she used AR so everything excluding Iridium can be there, as we have not seen the assay yet.

I completely misread that.
But still copper is the better choice to cement with than copper. If there are any values in this ore.

 

[MindyBeatty]

First off.
Leaching ores can be really dangerous if you do not have full control of what is in there.

Do you have a proper assay?

Next there is a lot of misunderstanding regarding Nitric as many call deNOxing for neutralizing.
This do not matter much as you have seriously neutralized it.
Why did you do that?
Did you find some procedure that works like that?
What was the pH when you were done adding NaOH?

Some base metals and even all the Silver, Gold, Palladium and what not will have dropped as Hydroxides.
The only one that not readily form Hydroxides is Platinum.

Then you used Zinc which will drop all metals in stead of using Copper.
Hydrogen Peroxide will not drop anything, but in HCl it will dissolve Gold and much more if it is finely divided.

I don't have an assay. I don't even know where to get one.

 

[MindyBeatty]

I completely misread that.
But still copper is the better choice to cement with than copper. If there are any values in this ore.

I have copper for my annode

 

[Yggdrasil]

I don't have an assay. I wasn't asking about my procedure, I am asking if anyone knows how to identify the powder I got by the provided pictures.

There is no way we can say anything about what is there at this point.
Any treatment of ores are dependent on the assay.
And before you neutralized your leach you could have done a Stannous test, this can not be done now.

So now you can take it to ICP or XRF and get an idea of what it is.

 

[MindyBeatty]

I did a stannous test. It was dark brown

 

[Yggdrasil]

I did a stannous test. It was dark brown

That is what we call a false positive.

Here is how it may look:

 

[Martijn]

I don't have an assay. I wasn't asking about my procedure, I am asking if anyone knows how to identify the powder I got by the provided pictures.

As said, anything less reactive than zinc.
You need to test it.
HCl dissolves most base metals and Pd. Precious metals can be dissolved in AR and tested for with stannous chloride. Silver and Pd dissolve in nitric alone.
Which precious metals are to be expected in your ore?

 

[MindyBeatty]

And of course I neutralized the nitric. How else would I get it to cement as nitric must be neutralized before you can recover. I don't get why that's such a surprise that I used urea before dropping.

 

[Yggdrasil]

As said, anything less reactive than zinc.
You need to test it.
HCl dissolves most base metals and Pd. Precious metals can be dissolved in AR and tested for with stannous chloride. Silver and Pd dissolve in nitric alone.
Which precious metals are to be expected in your ore?

Only Pd if it is very finely spread out.

 

[MindyBeatty]

As said, anything less reactive than zinc.
You need to test it.
HCl dissolves most base metals and Pd. Precious metals can be dissolved in AR and tested for with stannous chloride. Silver and Pd dissolve in nitric alone.
Which precious metals are to be expected in your ore?

Gold and silver

 

[MindyBeatty]

Only Pd if it is very finely spread out.

It won't settle. Not even overnight. It has red undertones.

 

[MindyBeatty]

That is what we call a false positive.

Here is how it may look:
View attachment 67291

There are other colors than that.

 

[MindyBeatty]

There are other colors than that.

Three test tubes on 3 different occasions is not a false positive.

 

[Yggdrasil]

And of course I neutralized the nitric. How else would I get it to cement as nitric must be neutralized before you can recover. I don't get why that's such a surprise that I used urea before dropping.

I have not said anything regarding Urea, even though we prefer Sulfamic acid.
And we do not call that neutralizing because that is to bring the solution to 7 which is neutral.
We call it deNOxing since we decompose the NOx to avoid re dissolution.

Red is probably colloidal Gold.
Add a splash of Peroxide into your HCl and it will dissolve.
Just that you will never see it since it is so small amounts.