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



## hauger (Aug 22, 2017)

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


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## kernels (Aug 22, 2017)

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.


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## Topher_osAUrus (Aug 22, 2017)

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?


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## hauger (Aug 22, 2017)

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


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## hauger (Aug 22, 2017)

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.
> ...



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.


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## kernels (Aug 22, 2017)

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.


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## kernels (Aug 22, 2017)

Also, pictures of what you are looking at now would be good.


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## hauger (Aug 22, 2017)

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.


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## jimdoc (Aug 22, 2017)

You can't post pictures from photobucket on third party sites anymore.
Unless you pay them.


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## kernels (Aug 22, 2017)

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.


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## hauger (Aug 22, 2017)

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


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## hauger (Aug 22, 2017)

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?


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## butcher (Aug 22, 2017)

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.


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## FrugalRefiner (Aug 22, 2017)

hauger said:


> Tough but fair. What do people use for image hosting instead? I looked but didn't see any image uploading in the forums.


See Attaching Images or Files, Working with Attachments.

Dave


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## butcher (Aug 22, 2017)

Thanks Dave, I printed a copy for reference.


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## FrugalRefiner (Aug 22, 2017)

butcher said:


> Thanks Dave, I printed a copy for reference.


 :lol: I've done the same with a lot of your posts! 8) 

Dave


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## kernels (Aug 23, 2017)

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.
> ...



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 ?


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## hauger (Aug 23, 2017)

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.


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## nickvc (Aug 23, 2017)

If you wish to remove any tin you will need to incinerate the collected powder and then use Hcl to remove the tin.


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## hauger (Aug 23, 2017)

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?


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## kernels (Aug 23, 2017)

Don't evaporate off the solution until you have the solution separated from the powder. Also, don't decant the solution, the powder is very light. Instead get a length of aquarium tube and siphon the clear liquid off, being careful not to disturb the settled powder.

If you still have colloidal Gold (looks purple), then it may never fully settle. I have managed to avoid colloidal Gold so far, so couldn't really advise about how to deal with that. But sort out the powders first, they are comparatively easy. I expect once you remove the Copper, everything will settle within 12 hours or so.

Regarding incineration, you don't get any powders hot enough to melt, just a nice red glow, this will give you metallic Tin, which you can then remove with warm HCl before proceeding with the re-refine.


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## hauger (Aug 24, 2017)

Okay, more question time. 

I've let it sit now copper free for 12 hours. I didn't expect a perfect settling but it's still quite dark brown. There is a "sludge" on the bottom of the container though.

I drew a small amount out and tested it with a few drops of Stannous. It went immediately dark brown/black. No hint of purple at all.

I've attached a few pics, one is the solution as it sits (the oil on top was my fault, introduced when drawing the sample), the second is post stannous sample.

I'm at a loss again. Do I wait? Do I process the "sludge" and dispose of the solution? I love the learning process of this, but I'm wondering at what point the effort outweighs the benefit vs. starting over with a new batch.

Thanks again for the help, you guys have been great.


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## butcher (Aug 24, 2017)

I am having some trouble following the thread, so I can be a bit off base here.
As I understand it:

The original solution had tin or tin salts with gold solution, forming colloidal gold in solution, this will not show up in a test with stannous chloride, it will basically never precipitate, it is elemental gold colloids held in solution by their electrical charge too small to settle and constantly being moved around in solution by particles of opposite charge, we will have to evaporate this solution to powders mildly heating these powders to drive off chlorides (a little NaOH can be beneficial here in the conversion), after most of the smoke has cleared further heating we can raise our heat to red hot crushing the crusted powders and stirring to provide oxygen from the air as we stir the red hot powders, converting many of the metals including tin to oxides or volatilizing many of them, Note they reason we are careful how we do these heating stages is because gold chlorides are also volatile, and we need to drive chlorides off as gas first without driving our gold off going up with the smoke.

I have, and others have, discussed this process, or problems in greater length, a search of colloids would be beneficial to a greater understanding of what your dealing with and how to deal with them....

Note: Not all of the gold may be in solution, or in the the powders... Would have formed colloids so we can deal with the solution later.

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As mentioned already testing for dissolved gold in solution, and determining the false positive from too much SMB, forming brown copper compounds in the test false positive test...

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The dark brown solution can be from Copper chloride CuCl, the settled brown/black powders can be gold mixed with other metals copper...
Here I would decant, test solution for gold, and then evaporate the solution and treat it for colloidal gold as discussed above...

The settled powder I would probably clean up with some HCl and a tiny bit of 3% H2O2, to put many of the other metals in solution, then wash the rest, with Harold's gold washing procedure, before refining them further.

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If this was a very small batch, I would just evaporated the whole lot, treat it all for colloidal gold in the evaporation and heat to drive off chlorides and red hot incineration process discussed above. Then save the little bit of roasted powder, until I had a lager volume to work with. working with small lots of gold increases losses in processes tremendously, a tiny loss in many many small batches add up to an appreciable lose of gold.
When working with larger lots a small loss does not show up as much.


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## galenrog (Aug 24, 2017)

While I can not add further to any of the advice given on the current topic, please let me interject with a bit of advice on avoiding future problems, and necessary recovery when something does crop up.

As you have learned in the past few days, Gold Refining Forum is populated with many experienced and helpful members. This information alone has proven invaluable to my own efforts. Following the advice of these folks will help in correcting nearly any mistake and avoiding future problems. As you continue your education here, you will learn whose advice is best for different situations.

Avoid YouTube. Most videos lack critical information on procedures and safety. Some are just plain wrong in every respect. Once you gain a little understanding of proper procedures and terminology, take time to go over videos recommended on the forum.

Read Hoke. Here that means read and study "Refining Precious Metal Wastes" by C M Hoke. Written in the 1940s, primarily for independent jewelers, this volume is probably the best primer for anyone interested in recovery and refining precious metals. The procedures and acquaintance experiments found within, with few modifications, are essential in learning proper procedures. Before performing any procedure outlined, please check the Forum to see if any modification of the procedure is suggested. I treasure my hard copy and have printed a few copies from links found is several member signature lines.

I make a printed outline of every procedure I perform. The outlines include needed and anticipated chemicals, tools, glassware, other hardware, and the purpose of each. A step by step flowchart with a few images. The flowchart includes what to do when different problems are encountered. I do this with even the simplest things. Why? If I have it written in front of me, I do not have to remember it. I have occasional memory issues due to stroke a few years ago. Such is life.

Label everything. Everything. Doing so means you do not have to remember what is in that jar on the back shelf. I avoid making codes, using only standard abbreviations where they will be easily understood. One of the neighbors is the Assistant Fire Chief, and has been very helpful in how things should be labeled from his perspective. 

Read and heed everything in the Safety section of the Forum. Everything. Take notes. Print out threads or individual posts for easy future reference.

I could go on and on, but you get the point. Preparation is everything. Besides, it is time for more coffee. I am thinking a good breve. Hazelnut. Heavy cream.


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