Recover Gold in "waste" wash - Beginner Demonstrating how much of a beginner

Gold Refining Forum

Help Support Gold Refining Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.

hauger

Member
Joined
May 24, 2017
Messages
24
Okay, I'm here to admit defeat and see if I can get a little help.

I tried a test batch of about 1 lbs of tightly trimmed fingers a few weeks ago. Everything went more or less to plan, dissolving the gold in AR, careful not to add too much Nitric Acid, precipitate, and (eventually) melt. I didn't have any Stannous though to test and make sure I wasn't leaving any gold behind, a rookie mistake I've learned since my yield was only 1.25g or about 50% what I expected (actually expected around 1.75 - 2 g for beginner inefficiencies).

Luckily, I saved my waste wash and left over solution after precipitating.

Fast forward to a few days ago. I dropped a few drops of Stannous into the solution as is (basically about 700 ml of previous AR and distilled H2O). Nothing. Frustrated I made a rookie mistake and squirted a bunch more Stannous into the solution (maybe 15 ml), but still nothing. Next morning though, the solution is dark and there's mud on the bottom. Okay, I know Stannous works by being a precipitant, so I guess the stannous precipitated the gold in solution.

Yes, I know the stannous would also contaminate it with tin, thus not ideal.

So my plan going forward was to evaporate off the excess, and kind of start from scratch, with washing the powder with HCL a few times to hopefully remove the tin, then re-AR the batch, filter, precipitate, and go from there.

Here's where I'm stuck...last night I was slowly evaporating the solution (not boiling). After a while, I checked and all the precipitated mud was gone and the solution was now yellow (with a green tint). Best I could guess is somehow evaporating created contaminated Auric Chloride somehow. I let it cool over night, and the solution stayed in the heated form.

Okay, I can maybe deal with that. I filtered the garbage off again (bits of board, etc) and figured I'd precipitate the (hopefully) gold off and go back to my original plan.....except no matter how much SMB I put into solution (fizzing and reacting nicely), it doesn't release the gold. It's still yellow but a little cloudy now (not good cloudy).

I'm not sure what my next step is. I'm assuming the tin is causing a problem but I don't know what or what to do. I'm not really concerned for the value in the gold as I am trying to learn and gain experience. I'm open to whatever advice/tips anyone may have.

Thanks
 
It sounds like when you did your first drop you had not neutralized all the Nitric acid, getting the Nitric addition exactly correct is very difficult, especially so for a beginner. Learn how to denoxx with Sulfamic acid to avoid this.

The problem with precipitation with Stannous is that you end up with very fine particles - colloidal gold. The correct approach is to put a few drops in a white plastic spoon and add a drop of Stannous Chloride to that.

When heating your solution, you likely re-dissolved any remaining Gold.

The better way would have been to put a solid chunk of Copper into the solution after separating off the gold that did drop the first time. Any remaining Gold would then cement out on the copper bar. The copper will also 'consume' any excess Nitric. This gives you a fine black powder - Gold - which you can then re-refine with the Gold you had already dropped.
 
You have a picture of the stannous sediment?

Colloidal gold can stay suspended for millennia(no joke)
So I'd be interested in seeing the powder, if you can.

And, I am a bit confused. You dropped the gold the first time before filtering off the bits of board and whatnot?
-you say you filtered off the bits of board again?
 
I can fully agree that mistakes were made. I kind of assumed I'd over HNO the solution on the first go as well, I was figuring I'd produce a button that I can use to avoid the problem in the future.

Having said that, in my current jam, is the best way to drop copper into the solution and see what cements out? How long would that process take (not that I'm impatient, just wondering what kind of timeline is involved).

Thanks
 
Topher_osAUrus said:
You have a picture of the stannous sediment?

Colloidal gold can stay suspended for millennia(no joke)
So I'd be interested in seeing the powder, if you can.

And, I am a bit confused. You dropped the gold the first time before filtering off the bits of board and whatnot?
-you say you filtered off the bits of board again?

I wish I had a picture (I looked but no luck). The board bits were filtered the first time, I forget how exactly but those board bits ended up in my "waste" collection, thus needing to be filtered again.
 
If you now have a clear solution with everything re-dissolved, then yes, putting a bar of copper in and stirring every few hours would be a good way to see what is going on. You cannot really go wrong by cementing out on Copper, you just end up having to re-refine if you want high-purity.

I would leave the copper in there for a day or two, but if there is any significant Gold in there you will see it start to cement out almost immediately. If you still have HNO3 in there then you will also see a bubbling reaction with the copper.

Solid bars are great, but hard to come by. I usually just split a piece of copper pipe so it's flat and put that in, allowing enough length that the top end is not in the solution so I can stir the solution with the copper every now and then.
 
Okay, copper is in solution. I didn't have any pipe to cut and split, instead I stripped some 14 gauge wire and hit it with a torch quickly to remove whatever coating is on the copper. It's reacting away, currently the wire is solid black and moving it slightly causes black to dislodge from it. I don't know if that's gold cementing or copper being attacked directly by the HCl in solution, but something is happening, so that's a win.

I tried adding pics but having trouble with the links from photobucket.
 
If you started with only fingers then there is not likely to be any other PMs in solution other than Gold, so your black powder is very very likely gold. Reaction with HCl turns the copper green-blue. Sounds like it is working correctly, just leave it for a day or two, then remove the copper and give it a spray down with a spray bottle. Then leave everything to settle in the solution for a day or so. Then siphon off the clear liquid to your waste treatment container.

You can then do a re-refine on the black powder together with your already dropped powder. But probably best to sort out some method of denoxxing first.
 
Tough but fair. What do people use for image hosting instead? I looked but didn't see any image uploading in the forums.

Also, thanks for the advice so far, appreciate it
 
kernels said:
If you started with only fingers then there is not likely to be any other PMs in solution other than Gold, so your black powder is very very likely gold. Reaction with HCl turns the copper green-blue. Sounds like it is working correctly, just leave it for a day or two, then remove the copper and give it a spray down with a spray bottle. Then leave everything to settle in the solution for a day or so. Then siphon off the clear liquid to your waste treatment container.

You can then do a re-refine on the black powder together with your already dropped powder. But probably best to sort out some method of denoxxing first.

Thanks, sincerely, thanks for the help.

Regarding denoxxing, I was planning on dropping in a button to "eat" any free HNO. Is this advised against, or are there better ways?
 
At the bottom (under where you are posting, There is an attachment folder tab (next to options), clicking on it you get a box that says add files, there you can find the file or picture you have stored in a file or on your desktop and upload it onto your post.

Harold's trick of adding a pure gold button and heat is a very good way to deNOx the solution.
 
hauger said:
kernels said:
If you started with only fingers then there is not likely to be any other PMs in solution other than Gold, so your black powder is very very likely gold. Reaction with HCl turns the copper green-blue. Sounds like it is working correctly, just leave it for a day or two, then remove the copper and give it a spray down with a spray bottle. Then leave everything to settle in the solution for a day or so. Then siphon off the clear liquid to your waste treatment container.

You can then do a re-refine on the black powder together with your already dropped powder. But probably best to sort out some method of denoxxing first.

Thanks, sincerely, thanks for the help.

Regarding denoxxing, I was planning on dropping in a button to "eat" any free HNO. Is this advised against, or are there better ways?

Using a gold button to 'eat' the excess Nitric works fine, but is very slow. I now only use Sulfamic (Sulphamic) acid, but still use a button in the solution to show me when all the Nitric has been converted. Sulfamic acid is sold as grout / tile cleaner in some countries, usually not too hard to get hold of.

How much black powder did you manage to get out of the solution ? Looking like it may be the missing Gold ?
 
So I checked out Home Depot and they do carry that as tile grout cleaner. Guessing that's my next purchase in my expanding chemical inventory.

There appears to be a fair amount of "stuff" cemented off, but still a lot suspended so unable to decant and confirm an amount. I was planning on taking out the copper tonight (after it's been in for 24 hours) and letting everything settle. Once I have an amount I'll post it. In the meantime, thanks for the learning.
 
If you wish to remove any tin you will need to incinerate the collected powder and then use Hcl to remove the tin.
 
nickvc said:
If you wish to remove any tin you will need to incinerate the collected powder and then use Hcl to remove the tin.

That sounds like fun. Wouldn't incinerating melt the powder into a bead? Would the idea then be to hammer it flat and put it in HCl? I'm assuming there's copper in the powder now too, so assuming I need to run it through AP to remove the copper too??

Follow up question, now that the powder has cemented out, can I evaporate off some of the solution, or do I risk loosing gold and/or causing the power to re-absorb somehow?
 
Back
Top