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

[kernels]

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.

 

[hauger]

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.

 

[butcher]

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.

 

[galenrog]

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.