Gold Stratification?

[AndrewSuperD]

When you said "the stannous surface layer shows no gold in solution" it sounded like you may have added stannous directly to your solution, now we know that is not the problem.

If you dipped a piece of paper into the solution and tested it with stannous chloride that should tell you the gold is reduced, you can try to pipette a few drops of the heavier liquid if you wish and see what it shows. Dipping a Q tip in the mix should get the tip wet with both solutions.

The gold looks like it came from a dirty solution of base metals, black and fluffy, this and other contaminants or organics, oils, could give you a situation where you have two different densities of liquids and where gold can begin to stick to the glass or get hung up in a layer of salts with organics or oils...

I cannot tell from the picture but it also looks like there was very little gold, to begin with, or much here now.
How does the solution filter? Does it just sit on the filter paper, or does it freely pass through the paper, (some metals can give problems with filtering is the reason I asked.


I would probably try to heat the solution and then see if the gold would settle overnight, or just filter the gold from the solution and move on.

When gold is in the solution you normally see sort of a halo or a yellow ring on the top edge of the surface of the solution at the glass's edge, I do not see that in your picture, yours looks clear, making me suspect your gold is reduced

Thank you again for the help. ”Fluffy” .. great description. I wound up boiling for 30 min or so. My rationale was that little bubbles existed on everything in the beaker and seemed to be holding up the lighter material. I thought boiling would drive more gases out. Don’t know if that makes any sense. The result was that stratification disappeared, all gold at bottom turned black and clumped together. I washed with boiling water. Im now boiling in HCl. (Took a break from it). Seems back on track now. Thank you for the advice.

So “not much gold”. Im going to wager it’s just shy of 1.5g. Which is very much less than I expected. So I ask myself, “where is my gold?”. I move slowly through these processes so I still have the original beaker with the “post incineration” carbon. Well well well…. It’s settled further over night and there’s a Golden yellow liquid in the beaker again. I hold it up in the sunlight, and man…there are more bond wires in the bottom of the beaker as I can see the gold grouped together. I guess the yellow liquid came from the remaining Nitric mixed with the tap water I washed with as I was pouring off my AR solution. I filtered that cleanly. Btw, the solutions filter cleanly and easily. Slowly because I’m using #4 lab filter + cotton ball crammed in funnel tube.

I thought my solution was clean, but based on the outcome of my first drop and the fact that gold bond wires remain in the original beaker, I have no reason to suspect the other base metals were removed by my original Nitric soak. I added nitric till there was no more reaction when I was performing the first nitric soak and processing with AR. But it doesn’t appear to have gotten to all the metals. I think that’s because the acid couldn’t get to the entire body of metals through the dense carbon mixture. So you’re right I’m sure, “dirty metals solution”.

You think I could just mix up another nitric bath and boil the heck out of it to remove base metals, then rinse and then boil in AR? I suggest boiling to agitate the suspension and allow the acids to reach the metals.

So I just checked on my boiling gold and now there’s something white in the beaker. Assume HCl salt driven out of solution due to evaporation? Added tap water, gave it a swirl and looking normal again. Pictures attached. Stannous Chloride test is colorless. I’ll decant, wash and melt tonight here in a few. Would love to have a recommendation on my thoughts above on the dense carbon suspension.

 

[butcher]

The gold has not been refined in my opinion, you have recovered gold from a dirty solution.
Refine the recovered gold.

Not always needed but helpful. It would not hurt to incinerate the gold powder, you could do this with filter paper or without, if paper or carbon or oils are involved, incinerate the gold till it glows red hot under the flame in the air, and where all the paper decomposes to white ash, besides oil or carbon, this can help if tin is involved to oxidize it and help remove any salts of previous acids.
If you suspected tin, a wash of the gold HCl of the cooled gold will help,
Harold's gold wash technique works wonders.

It takes only a very small amount of acids to re-refine the gold powders. Start with about 4ml HCl and 1ml HNO3 (dropwise as needed with a little heat and time till all the gold dissolves), for each gram of gold powder.
If lead, sulfuric acid, or forming sulfuric in a reaction will help precipitate the lead sulfate from the solution. Being mindful of settling time, decanting, and filtering...

The second pictures look like you have more gold than the first picture did, looking good so far.

 

[AndrewSuperD]

Thanks a bunch. You are exactly right, the gold needs to be refined. However, I need to finish the other 1/2 of this batch and button this project up till after Christmas so I’ll refine then. I have four beads that need to be refined. I just made my fourth bead. Not the best, but attached is a picture of all four. Gold is apparently very difficult to photograph. I don’t know why the left two look black on top, they are beautifully shiny gold.

If I can discuss in terms of basic processing method AP or Nitric for initial gold separation; the first two are from pins and processed with AP then AR. The third from left is from small batch of old A drive pins and processed with Nitric then AR. The fourth from left is from 2 sided IC chips and processed with Nitric then with AR. The pictures don’t do the first and second beads justice. The third and fourth are no where near as pure or attractive as the first and second. The third and fourth need refining the most. Especially with needing refinement, I think I should have had more gold in today’s button from the IC chips so I’m very disappointed. Based on the amount of gold still in the original beaker, i may have a little more than I processed today. Very disappointing over all. Maybe my Nitric processing needs improvement, Or maybe the IC chips I had were just really low quality, Or maybe there’s more than I think still in the original beaker?

At any rate, thanks a ton for the help and encouragement. I’ll tackle the rest of the original beaker this week.

 

[orvi]

Very disappointing over all. Maybe my Nitric processing needs improvement, Or maybe the IC chips I had were just really low quality, Or maybe there’s more than I think still in the original beaker?

At any rate, thanks a ton for the help and encouragement. I’ll tackle the rest of the original beaker this week.

processing chips is sometimes hit or miss. one batch you score 2,5g/kg, other 0,4g/kg could happen anytime to anyone. incinerating and recovering gold from ICs is matter of quantity. below 0,5g Au per batch, whole process and recovery of fine gold drop is very painful and not much rewarding on the other hand, getting few kilos of IC chips incinerated without health hazard and annoying neighbors with smell or fumes is the other thing

dissolving entrapped gold from complex matrix of burnt plastics ashes, silica filler, fire retardants and stuff is tedious process. if you have more of this material, in your position, i will be thinking more about smelting incinerated chips with proper flux. separating magnetic and non-magnetic stuff will help. magnetic stuff (separated from bulk of burnt trash) should be readily dissolved in HCl/AP or even AR. non magnetics smelted down with some borax flux recipee to mainly copper/little AuAg ingot...if done with oxidizing flux and in non-graphite crucible, good portion of tin and lead will be removed to the slag too. and you go from there, with "clean" metal, either dissolution with AR or electrorefining, if ingot is sufficiently pure copper.

 

[AndrewSuperD]

Hmpf!!! Well, tonight I checked on the solution. I boiled the lot in AR again and the whole mess is now brown and testing negative for gold. The bit of yellow liquid I decanted from the exact same beaker (before making fresh AR an boiling) tested and is still testing positive for gold with Stannous Chloride. I imagine the gold could have cemented onto something in suspension but what? Or it just wasn't really there. I may be ready to move on from this batch :\