Gold plating recovery

Have you thought about trying make a centrifuge set to speed the settling process.
 
Have you thought about trying make a centrifuge set to speed the settling process.

Yes, several times. I always come to a full stop in the thought process when I remember I'm going to be slinging around 94% sulfuric acid. o_O
 
Yes, several times. I always come to a full stop in the thought process when I remember I'm going to be slinging around 94% sulfuric acid. o_O

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Yes, several times. I always come to a full stop in the thought process when I remember I'm going to be slinging around 94% sulfuric acid. o_O

LOL I understand

I was thinking a large round tub with something like an old record player with a wood deck. Use small plastic ( it won't eat plastic will it?) jars and run at slow speed. I would use a cassette set up- round circle of plywood with a rim made out of hose and then another circle to sandwich jars.
 
LOL I understand

I was thinking a large round tub with something like an old record player with a wood deck. Use small plastic ( it won't eat plastic will it?) jars and run at slow speed. I would use a cassette set up- round circle of plywood with a rim made out of hose and then another circle to sandwich jars.

When I was trying to come up with a solution I imagined something like a counterbalanced g-force tester, where the carriage pivots from vertical (stopped) to horizontal (full tilt) so the jar of solution could stay in the carriage relatively undisturbed while still in the jar. Kinda like the carousel in a blood centrifuge. But the weight of the jar really worried me. I'll take the scale out and weigh it later. It's really really heavy. I envisioned the bottom of the jar coming off and ....well, see BOOgers post.
 
I would think maybe 6 -8 jars laying flat like a wheel, going at slower speed at longer time would be fine- you can go quick at fast speed or slow at long time and get to same results.
 
No reason to be in a hurry, it doesn't have a sell-by date ;)

They key to all gold recovery is the cost of labor and materials vs the net values. Folks would be surprised to know how many gold mines were swallowed up by the Charlotte suburbs. What closes gold or silver mines is not the lack of precious metals, its the cost of digging and refining them versus the market price. eg, not commercially viable. It is very expensive to operate a mine operation on any scale and most all take scaling up for production. If gold is $1650 an ounce the most efficient mine might make a couple hundred bucks- tops- on that ounce. For many, its even less, maybe $50.

The image most people have of a miner is a grizzled old dude in a tunnel with a mule with tons of gold. No, that would probably actually be a prospector, poking around sampling for years on a shoestring, hoping to find enough gold in samples, have it assayed, stake a claim then sell the claim to some mining company who then could raise enough capital through selling shares ( stock) in the mine to actually develop the claim and process gold. There are many stories of folks who made tons of money during the gold rush. These would be the people who supplied shovels, pans, tents and mules. It was called "Mining the miners" and the principle applies to many other activities today,
 
So I went to check on the sulfuric acid, after 9 more hours the gray goo settled down to about an inch, so I'll be able to recover the bulk of the acid for reuse when I fire up the cell again tomorrow night.

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The jar weighs almost 9lbs. Forgot that sulfuric acid is so heavy at 15 plus lbs per gallon.

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It must be lead. Overnight it settled down to just a few mm.

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As of right now, gold is running $55.20/g. The first 10lbs of material netted me 15.3g - I have about 0.5g waiting in solution for the next batch that's processed. I'm a little disappointed in the yield, but I'll take it. I made have had some losses due to inexperience so we'll see how the next batch goes. The photos don't reflect the color very well, but holding it in your hand it *looks* like 24k, it's a very hard to describe deep gold color unless you've ever seen 24k gold. My limited testing capability shows it's greater than 22k. I can easily dent it with my fingernail.

It's worth about $800, so far that means about $510 profit and if I get the same yield on the remaining ~30lbs it'll be about $2900 profit total. I was expecting twice that but that was probably me just being greedy and overly optimistic. More than $10 hour, but not a lot - at least I learned something.

Ok, $2890 profit. Jenny is a little bent out of shape that I'm using one of the pyrex baking dishes and seems to think it's now somehow tainted. I'll just replace it to keep the peace.



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Restarted the cell today and spent a few hours early this morning processing while the temps were still cool. Once the shop heats up the acid quickly gets warm. After the acid hits 125° it really starts to attack the copper basket and it's time to wrap it up for the day.

Eventually the below video will become part of a start-to-finish video showing the deplating, rinsing, AR bath, rinsing, acid wash(s), more rinsing, and melting.

It's kinda neat to watch all the gold (fine black powder) start to saturate the clean cell. 17 minutes compressed down to a minute.

 
THAT is interesting...

I may have missed it earlier, but you have somewhere to sell it once it's been refined?
 
THAT is interesting...

I may have missed it earlier, but you have somewhere to sell it once it's been refined?

Not really. Was just planning to ebay it. From what I've seen I should be able to get nearly spot.
 
This is still one of the coolest threads. Yeah, yeah, I'm a nerd..

Thanks! I should have an update tonight. Made some new holders in hopes of speeding things along by aligning the pins right from the start. Haven't really touched it since last weekend waiting on new (old) battery chargers. Thanks a bunch @Jeppo and @thecarman .


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Re-Screening the "basket" every 8lbs was becoming a pain. Once the acid gets hot the corrosion on the copper prohibits good electrical contact. Plus I had to fidget with the pins frequently to get them lined up to remove the gold from the hollows on the ends. Vertical seems to be the ticket. So I built the above holders. The one in the top photo looks like it would be really unstable and the pins would fall off if you looked at it wrong but it's really very stable.

The problem is there are 4 types of pins in the bucket. The first is really small ones. I hate them, fortunately there are very few of them; I might grab one in every other handful. They'll end up getting processed in the basket at the end. No pic of those - because I hate them - they're not worthy of being photographed.

The other three types....

Pins are in the same position in all three pics.

One end...
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Other end...
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Top view... 20200501_145104.jpg

The chunky pin on the left has hollows on each end, in the above pic the top end is deeper than the other and the hole diameter is a "red one" narrower than the other end. The holder is made to hold the pin in this orientation. There's also a very small hole in the side of the pin at the "top" of the bottom hole, I'm hoping that this orientation helps the gasses escape (it seems to be working)

The other two types of pins will go on the goofy looking "spider" holder. The middle pin has deep hollows at both ends and often goes full potato in the deplater oxidizing to copper very quickly. Side edit: I bought these pins as gold plated brass for another project. There is no brass here. It's all some kind of gold plated copper. Not pure copper, it's very slightly magnetic and kinda looks like dirty brass, and not super conductive like pure copper, maybe beryllium?

The pin on the far right is completely hollow with plating all the way through, it has the most gold. It also is very light weight. These typically deplate very quickly and very thoroughly.


I also recast the cathode into a more stable shape and so that it will sit above the pins. I read that helps and I'll take all the help I can get. It's obvious in the video that the mystery grey goo that took days to settle is definitely lead.

Random shots of the holders.

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More video goodness. Video should be done processing on youtube around 12a 5/5. Video editing is a RPITA, I don't know how those guys who make their living on youtube have time for anything else - this little video took about 2 hours to edit (text, speed, slicing...)



ETA: At 5:19 you can see the third pin from the left didn't de-plate at all. It just sat there. This video is made from two clips near the end of this run. There is a very distinctive sweet spot in the acids temperature, around 80-110 degrees. When I started this run it was around 50 degrees and v-e-r-y slow with much less amp draw. The first batch took about 10 minutes. Deplating starts to speed up as the acid warms up. Once over 115 deplating becomes very erratic, incomplete, and very frustrating. Also forgot to mention, I weighed everything, I'm about 13 lbs into the 38+ with ~25 to go. I might be done by June - BUT I only get out there for a few hours every few days,
 
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I’m starting to wonder if stainless chips in a tumbler wouldn’t deplate the pins for free, then you just pan out the gold. Maybe finish with a little acid wash to remove any remaining base metal. Not as cool as chem lab, but less dangerous and probably a lot faster.
 
I want to learn to do this so badly.

It's really pretty simple. Learn some basic safety for working with acid. Hardest part is sourcing nitric acid, but I should have some left over at the end of the process - you can use household bleach in place of nitric in a pinch. I'd say swing by to watch, but the deplating process is super boring, and there is a lot of very extended wait time between refining steps to allow everything to settle. Reach out if you have questions, I can point you to some videos that helped me, and a reafining forum. That's how I learned, I have no background in chemistry.
 
I’m starting to wonder if stainless chips in a tumbler wouldn’t deplate the pins for free, then you just pan out the gold. Maybe finish with a little acid wash to remove any remaining base metal. Not as cool as chem lab, but less dangerous and probably a lot faster.

Since I'm processing one type of pin at a time I went ahead and separated them all. I had 350ish grams of the thin crappy pins so I sacrificed them to experiment.

I soaked them in AR and watched the pins go to copper fairly quickly then stopped the process with urea, filtered, and dropped the gold. It's a dirty nasty solution but the gold does seem to be settling out. I'll post up the results in a few days after a few hot water rinses and acid washes and more hot water rinses.

It was certainly faster and much more complete, but I'm also sure I got more copper into solution.
 
Since I'm processing one type of pin at a time I went ahead and separated them all. I had 350ish grams of the thin crappy pins so I sacrificed them to experiment.

I soaked them in AR and watched the pins go to copper fairly quickly then stopped the process with urea, filtered, and dropped the gold. It's a dirty nasty solution but the gold does seem to be settling out. I'll post up the results in a few days after a few hot water rinses and acid washes and more hot water rinses.

It was certainly faster and much more complete, but I'm also sure I got more copper into solution.


That was a failure. No idea why. When the reaction started I could see gold going into solution, and the solution tested positive for gold. I don't know what happened but I never saw the presence of gold again. It went somewhere, but I have no idea where. I'll stick to what I know.
 
I'm a little over a third done. I cleaned out the cell before going on vacation last week, that yielded another 7g. I also tried dissolving around 2lb of the oddball pins in nitric so that only gold foils remained. It worked but was slow and used a lot (1+ liters) of nitric, nitric is the most expensive chemical I'm using and the hardest to come by. That yielded another 3g.

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I needs a good toof
 
Been meaning to post this. I had a buddy from off forum following my progress and donated 15.75oz of small plated pins on the condition I'd video the process using nitric acid. They were small pins that wouldn't de-plate well in the stripping cell. I had to cut the pins in half - all 1100+ of them - in order to give the nitric easy access to the base metal inside. I only included a small clip of the nitric dissolution process as it was 10 hours of gold pins boiling in blue goo until they started to float. The bulk of the video is what happens to the gold foils after all the base metal has been removed.

No, I'm not wearing gloves. Yes, I know I'm a dumbass, we already established that in another thread. I am wearing safety glasses if that helps with personal redemption.

I think the yield was 3.7g. 446.50g to start = 0.0082 yield - way higher than expected. I've still got about 25lbs to process.

Looks like I forgot to explain the denoxing process at around 12:00, just adding urea to neutralize any excess nitric. I'll keep adding until there's no more reaction. If you don't denox the precipitate will go right back into solution.

 
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i wonder if putting it into a tapered flask and fractioning out the gold precipitate would clog it all up or work better than trying to decant. For something that settles that easily, decanting is probably a bit easier.
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one of these things
 
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i wonder if putting it into a tapered flask and fractioning out the gold precipitate would clog it all up or work better than trying to decant. For something that settles that easily, decanting is probably a bit easier.
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one of these things

For now decanting is the way to go. Between the mud settling out and melting the shiny bead there are several small washes in HCI to burn off any remaining impurities, then several washes in boiling water to remove any soluble salts. It's way easier to just swirl it, let it settle, decant, lather, rinse, repeat. Once more and more impurities are removed from the mud it starts to clump together like in this earlier pic....

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For now decanting is the way to go. Between the mud settling out and melting the shiny bead there are several small washes in HCI to burn off any remaining impurities, then several washes in boiling water to remove any soluble salts. It's way easier to just swirl it, let it settle, decant, lather, rinse, repeat. Once more and more impurities are removed from the mud it starts to clump together like in this earlier pic....

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Yeah, I figured there were some extra steps that would require additional work if you used the separation funnel thing.
cool
 
So the guy who bought the button sent me a pic of his XRF testing my gold.

99.86% pure! I calculated 99.49 but had no way to verify it. .14% copper.

23.97K

Can not believe I learned how to do this via YouTube.

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It's been a few years. 18lbs left. Back on the bullspit. Yes, I'm listening to the Rogan/Dr. Phil podcast.

Going slower this time, 2 pins at a time. I find I get a faster deplate and a more complete deplate in the hollows of the ends. The hollows would amount to 30% more yield. Forgot how slow it is. Moved the operation from the shop to the garage where I can make heat and have wifi for tv/phone.

 
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