Black powder with Gold Powder in HCl/CL

[adam_mizer]

I thought I would post this looking for some feedback on further cleaning/saving powders.

Some black powder is in with my gold powder.
The AuCl is the best color I have ever seen, a heavy yellow red more on the red side after this powder was processed twice.
Powder came from poormans AR, salts silvers coppers dropped and filtered out.
Have a feeling I made a mistake at one point and had a very warm solution when I did a drop/filter in the process.
It very well may have been this warm solution that took some black powder in, don't know.

So this is he 3rd time I am processing this particular powder, a small amount but doesn't matter as it has this problem.
Have 25ml water left from washing/rinsing on the powder, add 100ml HCl no reaction on the powder, add 25ml clorox instanly top layer black and some gold powder went into solution, stirred. Noticed that the brighter gold powder still sat on the bottom of small beaker. Let it sit for a couple days since I had some other stuff being processed, so just a tiny bit more of the bright gold powder went into solution in 2 days.

Finally poured the mostly seemingly red AuCl into a beaker and left the residual bright tan gold powder with a small amount of darker powder that did not go into solution.
Added small amount of SMB to this primary pour off, what appears nice is the SMB drop of the pour off above left a metallic colored layer on the bottom of the beaker (some AuCl still in solution).

Added some distilled water to try and pour off the remainder left over Hcl/Cl in original beaker with gold powders, but I left this because after adding the small amount of distilled sprayed right into the gold powder it turned black suspended into solution).

It seems that at a certain point of water mixed in I can get the black powder suspended into solution and hopefully filter it out.

Any ideas what this black powder is?


As a new guy I'm trying to focus my beginning refining methods further into dealing with some small problems that arise.
Hope I am going about this in a proper way.

 

[4metals]

I have a minimal amount of experience using poor mans AR, and all of that came from my experiments using methods here on the forum. In essence I'm a straight aqua regia guy, nitric and hydrochloric. However when you post a question like this my mind kinks into science mode and I ask myself a few questions. OK what's not soluble in aqua regia? Nice sized list pops into mind, OK re-read the post to see what the history of the material is, where did the original powders come from?

HMMMM no mention of what this material started out as. That is very important. If it was clean mixed jewelry, the simple answer could be silver, ruthenium or iridium. But if this came from electronic waste the list grows. My point here is it is very helpful for you to approach this problem in an organized scientific way, simply ask yourself what will not dissolve in the particular solvent I am using? Eliminate the obvious by considering what was there to begin with. Then if you still can't figure it out, please tell everyone you are asking all of the questions and answers you should be asking yourself.

 

[adam_mizer]

Sometimes the brain can f?!t on required information.

Preliminary materials is a good point.
Now it comes to mind 2 processes were involved.
Poormans AR with ceramic CPU's.
Also added now that I think of it was: sulphuric cell process, cpu plates, few plated coaxial connectors, but here's the interesting one: a few pieces of laser diodes of a couple different kinds.
These parts are small but there was 5 pieces of maybe a c-mount type of diode I think its called.
This diode would not stop fizzing in the sulphuric cell. (Which I cleaned and set out to the side).
I let each sit in there for maybe upto 5 minutes and tried only about 5-6 pieces.
This diode maybe my powder problem.

Sometimes you for get these things when you have other items in the cooker.

EDIT add: Here are some pictures, all of this was from the AuCl last picture.

 

[adam_mizer]

Here is the small amount of dried black powders.
There is gold mixed through-out and the dirty gold black powders.

Its like a tiny sample of what you would throw away, from bottom of bucket SMB and AR left overs.
This is like the last fine powders that take forever to settle.
Finally got a good close look at them.
Once dried they do not amount to as much as you think you see.

Letting these escape in your toss aways, would add up eventually.
This tiny amount contains considerable amount of gold when seen under some magnification.

It bothers me that this small amount contains traces of other metals which most possibly have stuck to the fine particulate powder of gold and is dragged through the clean-up process even when done several times over.
Its a tiny amount but still is a flaw taken in right from the first filtering, if something is incorrect.
Funny thing is the tiny particulate does not get washed/rinsed out in HCl, it will go into HCl/Cl.
Maybe I'm too anal but the more I understand the more pure I will get my gold powder.

 

[butcher]

I would try incinerating, rinse hot water , hot HCL more water till clear, dry, incinerate again, this time wash with water then nitric acid dilute and water till clear, (if washes are colored you are getting out metals), then re-dissolve this powder in true aqua regia, 3 slow evaporations, adding HCL to keep liquid between evaporations of NOx gases, few drops of H2SO4 to remove lead, 3 times water volume let sit overnight decant and filter solution from silver, lead chlorides, precipitate gold with ferrous sulfate, let sit overnight decanting solution teast using stannous chloride, wash gold using Harold’s washing technique, test solution for PGM if suspected, re-dissolve gold again in Aqua regia and re-refine the powders using same technique but use SMB for this last precipitation of gold washing again using Harold’s instruction.

 

[Oz]

It seems you have several feedstocks that this precipitate is made up of. I’m betting that some PGM has gotten into your material since it is mainly the ends of gold precipitations that are giving you this. You also described your gold re-digestions going yellow then red, without passing through orange.

I would dry your precipitate and inquart with silver. Of course follow proper steps before precipitation and follow recommended washing procedures.

 

[shyknee]

one quick question, Adam_mizer. Did you add 3 times water and chill settle and filter, before you added SMB.?

 

[adam_mizer]

There's one time in this process in it's beginning I filtered the batch while very warm, and this may have let some contamination through the chain.
(edit add And I use poormans and thought it is to add 2 times the water

Also not good to and I did, is to clean out the bottoms of my pour offs and then mix that in with accumulated powders from more than 1 method.
I say not good to do because I am still not experienced enough to process a mess of various powders that may have tiny contaminents from PM's.
Also another problem was certain laser diodes in the sulphuric cell never stop fizzing away, something may have come from this.

Getting ahead of myself trying to toss in all the washed fine powders from bottoms of bottles thinking it should clean out undesirable metals from only the general processes I have used and know.
Now its getting to the point I need to learn how to use nitric and other acid and hydroxide combo's in an effective cleaning/washing manner.

Here is one of Harold_V's posts, and I found many similar searching around.
What I'd suggest you do with this material is give it a good incineration, then give it a wash in dilute nitric, followed by a good rinse with (tap) water. Follow that operation with another incineration (to kill the nitric), then follow up with a second wash in HCl. Crush the material with a mortar and pestle after each incineration, and screen if necessary. Each incineration should take the material to a dull red heat, but do not melt.

After the second wash, rinse (tap water is acceptable) until the rinse solution is clear of color, then dissolve the material using AR, evaporate, adding a few drops of sulfuric acid, filter and precipitate. Apply a good washing procedure after precipitation. By following these processes, you will have effectively removed any troublesome materials and will have a solution that lends itself to easy filtration. The end product should be of excellent quality.