HCL / CL fail

[oldgeek]

I must be missing something. Every time I try to use this process, it just does not work out the way I think it should.

This time i am re-processing about 25 grams of powder I have collected from various sources. The powder looks pretty clean (light tan) to start with, and this will be the second run for it.

I started with 400ml of HCL, then I added my powder. I started adding bleach in 20ml increments. It appeared to work properly at first, but then it seems to stop working. I have added 200ml of bleach over 4 hours, and I still have quite a bit of undissolved powder on the bottom along with what looks like "curds". After it settles, I have nice golden color liquid with about an inch of white material and some undissolved powder on the very bottom.

I pretty sure from previous posts that the "white material" is from the additives in the bleach, next time I will get a stronger bleach (CL). But, I don't understand why i cannot get all of my powder to dissolve.

Thanks in advance
OldGeek

 

[philddreamer]

Hi Oldgeek!

Do you have nitirc acid or sodium nitrate? Those would work much better and faster on the 25g of gold powder than the clorox. Was plain bleach or scented?

Take care!

Phil

 

[oldgeek]

Hi Oldgeek!

Do you have nitirc acid or sodium nitrate? Those would work much better and faster on the 25g of gold powder than the clorox. Was plain bleach or scented?

Take care!

Phil

Hello Phil,

I am out of nitric, and do not plan to get any more. I just do not have the proper area to work with it.
That is why i have been trying the HCL / CL process. I guess I will give poor mans nitric a try.

The bleach was plain, and a different brand than the last time i tried this process, but it still did not seem to work properly.

 

[lazersteve]

Oldgeek,

Lots of stirring, a little heat (60C max), and patience is the way to get that much gold powder into solution with HCl-Cl. If you start getting salts simply filter out the solids and start with some fresh HCl on the solids and begin adding bleach with low heat and stirring. When you get everything dissolved combine the clean liquids and precipitate.

Steve

 

[oldgeek]

Oldgeek,

Lots of stirring, a little heat (60C max), and patience is the way to get that much gold powder into solution with HCl-Cl. If you start getting salts simply filter out the solids and start with some fresh HCl on the solids and begin adding bleach with low heat and stirring. When you get everything dissolved combine the clean liquids and precipitate.

Steve

Ok, Thanks for the help.

Is it necessary to dilute before final filtering and precipitation?
Also, will letting the solution set for 24-48 hours be enough to rid the solution of excess CL before I precipitate?

I had trouble with much lower than expected yields when using this process on finger foils the other day...I will have to visit that solution again.

Man, I just get so frustrated sometimes. :x

Thanks again!

 

[lazersteve]

Heating during dissolution serves two purposes:

1. Speeds dissolution of gold.

2. Expels excess chlorine.

No need to dilute or wait using it this way. Be sure to filter it 100% transparent before adding precipitant.

Steve

 

[rich_2137]

Hi oldgeek
I had the same problem but before I filtered the solution the white looking deposits completely dissolved with water when I diluted it to a 50/50 mix

Rich

 

[oldgeek]

Well I give up...for now.

I have worked on this all day. I started using heat as suggested, mixed like mad, poured off HCL to the filter, and added fresh HCL to the solids. That has definitely helped, but I still have some powder that has not gone into solution yet.

I will be using AR if I end up processing this amount again.

 

[Geo]

Well I give up...for now.

I have worked on this all day. I started using heat as suggested, mixed like mad, poured off HCL to the filter, and added fresh HCL to the solids. That has definitely helped, but I still have some powder that has not gone into solution yet.

I will be using AR if I end up processing this amount again.

various sources? are you sure its all gold? what, will not dissolve in hcl/Cl? did you incinerate the material before you tried to dissolve it? could it have oil or paint or anything else that would stop the dissolution?

 

[oldgeek]

various sources? are you sure its all gold? what, will not dissolve in hcl/Cl? did you incinerate the material before you tried to dissolve it? could it have oil or paint or anything else that would stop the dissolution?

My "various sources" were an inquart or two, and a couple small previous HCL / CL disolutions.

The well washed powders were in a sealed pill bottle, so there should be no oil, paint, or anything like that to cause issues.
While they were fairly clean, light tan powders, I did forget the golden rule (sorry Harold) I did not incinerate.

In the first picture, the one on the left was done without the use of heat. The one on the right was done with heat, and is the nicest looking deep gold color I have ever done. 8)
The other pictures are the stubborn solids that have not yet gone into solution. There third, and last batch of solution (about 250ml) is in the filter still, and is lighter in color than the first batch so I don't know whats up.


[ATTACH type="full" alt="gold in solution.JPG[/attachment
[attachment=1]powder1.JPG"]2[/ATTACH]

 

[lazersteve]

Inquarting tends to leave traces of silver chloride in the gold. These traces make dissolving the gold powder stubborn.

I would use poorman's AR or true AR for this type of material and you will still have difficulties dissolving the last of the solids.

I reserve the use of HCl-Cl to foils and the second refining of gold powder.

Steve

 

[oldgeek]

Inquarting tends to leave traces of silver chloride in the gold. These traces make dissolving the gold powder stubborn.

I would use poorman's AR or true AR for this type of material and you will still have difficulties dissolving the last of the solids.

Ok...That makes good sense. I did wash the inquarted gold powder with ammonia, but I can see how it would not take much silver chloride to interfere at this point.

I reserve the use of HCl-Cl to foils and the second refining of gold powder.

Steve

Not sure what you meant here...this is the second refining of the powders.

Thanks
OldGeek

 

[eeTHr]

oldgeek---

I see where you said that you added fresh HCl to the powder, after pouring off the old.

You didn't say that you added any Chlorox to the fresh HCl, though....

 

[lazersteve]

The second refining is performed after the gold has been recovered (inquarting) then refined once (dissolved the first time and precipitated once).

Steve

 

[oldgeek]

oldgeek---

I see where you said that you added fresh HCl to the powder, after pouring off the old.

You didn't say that you added any Chlorox to the fresh HCl, though....

Sorry, I forgot to mention that part. I did add more bleach several times as i mixed the solution.

The second refining is performed after the gold has been recovered (inquarting) then refined once (dissolved the first time and precipitated once).

Steve

Got it... Thanks again for your help.