It's not that it cements copper out of solution, it's that when it's saturated you have copper (I) chloride precipitate out of solution. And you are right, it does concentrate the values....but so much of modern e-waste is just flashed garbage. I have 500 lbs of pins that recover at 0.3g/lb, it's just not worthwhile to do anything to them except send them to the copper smelter as I can't CN strip them here.
Step by step instructions for AP processing circuit boards
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Copper won't cement copper out, but aren't most pins brass? And since brass is copper and zinc, could the zinc be what is cementing the copper out? I don't know. I'm just thinking out loud.
Dave
Dave
Even if the zinc in the brass cements gold if you filter and save all the solids, and check the solution with stannous, you will get it in the insolubles on the filter. Now if you set the pins tumbling and go on a 2 week vacation it is another thing. But if you check it often and stop when the pins are stripped you will have left a lot of brass intact and not wasted acid on it. And that is the purpose.
I agree with letting them go just long enough to get the majority of the gold loose. I did this fairly often at times. I was always running my own material so sending some to the stockpot was fine with me, I would get it eventually. Trying to explain to a beginner how to do this would be the biggest problem I think. As for the copper, I used to use gouging rods for burning out bad welds, a carbon rod coated in copper, to form an electrolysis cell. Removing enough copper to still be AP for reuse. As my grandfather used to tell me, better to spend dimes to collect dollars than spending dollars to collect dimes.
Is he the same grandfather that quoted Eleanore Roosevelt to you? Wise man!
Have you ever done this? Tumbled pins to release the gold, then wash the remaining brass. Curious if you assayed the brass afterward.
I get the concept, but it has always felt a little too incomplete? There's a lot of ambiguity in not knowing if you got all the gold, or even a majority of it.
Sorta like running CN without spectroscopy. When you don't have stannous or spectroscopy to tell you where your gold is, it's a little too magic for my inexperienced mind. And that makes me nervous.
Yep, the very same one. I spent every minute I could with him and never regretted it.
If you want to collect the remaining gold, I used waste AR to dissolve the remaining pin material. Once they finished dissolving I treated it just like the rest of my waste. I did later use a copper cell at times for the experience, but it wasn't necessary. I couldn’t afford to waste it, so I used the stockpot to get the larger quantity later from multiple smaller refines. If set up right, I often could use 1 1/2 gallons of that waste to dissolve a 4-5 ounce bar in three to five days, and self precipitate the excess copper as the white form of copper. But this is an AP thread and really trying to stick to it, it just kind of overlaps a few others things I did that might be a side track issue.
Another good example on the topic of asking a simple question and getting a simple answer.
I love this forum , sometimes I spend days going down rabbit holes and learn different approaches , methods, etc .
I would like to ask about or clear up a topic that I thought Harold mentioned that once AP/ Cu ( II ) Cl2 becomes saturated with iron it can dissolve silver .
I think he boiled it , is this true ?
So the next thing to clear up is does it matter ferrous vs. non ferrous pins can’t I just keep adding HCl To dissolve base metals . Now I’m using AP / Cu ( II) Cl2 to dissolve the legs off my chips and some boards that have been cut up , so I was just going to dump my low grade pins in this add a little HCl and bubbler , instead of sulfuric acid stripping cell or would the sulfuric acid cell be a better choice ?
As always thanks
Jeff
I would like to ask about or clear up a topic that I thought Harold mentioned that once AP/ Cu ( II ) Cl2 becomes saturated with iron it can dissolve silver .
I think he boiled it , is this true ?
So the next thing to clear up is does it matter ferrous vs. non ferrous pins can’t I just keep adding HCl To dissolve base metals . Now I’m using AP / Cu ( II) Cl2 to dissolve the legs off my chips and some boards that have been cut up , so I was just going to dump my low grade pins in this add a little HCl and bubbler , instead of sulfuric acid stripping cell or would the sulfuric acid cell be a better choice ?
As always thanks
Jeff
Volume and speed is how I determined where the pins went. Need them quick, a cell. If you can wait AP. Low grade pins aren’t likely to make serious money for the average home refiner, so I used AP by adding small handfuls of low end pins here and there. The down side is the other materials in pins foul the AP. If the content happens to be iron, it can be used as ferric chloride. Hot ferric chloride will eat iron and copper, but eventually will foul both. Container volume determines how far it can be pushed. I have not tried using it to dissolve silver, but silver does seem to be a common contaminant in gold from ferric chloride. I guess what I am saying is each individual has to determine what is in their best interest at the time. My health often determined how big of a hurry I was in and this made it easier for me to work at it for long term results more so than the quick side. AP lends its self to more materials if time isn’t an issue.
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I have been thinking on the cement mixer/ AP drum. With a way to bubble air into it, maybe a rotating connection(?), this could be a great way to do some materials and pins. It made me think of the rotating plating barrels, maybe a larger version even boards could be run at times? Anyone else still thinking on better ways to do this?
This little guy from a plating shop tumbler will work well.
I really like that and can see many ways to use it.
That was from a smaller refiner in Detroit using it to tumble chemical stone removal in thiosulfate. It was geared down to a few rpm but all encased in the housing.
I found this design for a 5 gallon pail that all refiners have!
For the DIY types
For the DIY types
From my experience with stripping pins in iodine leach, gold re-precipitation behaviour is very nice on copper and also on nickel - meaning that formed gold precipitate do not cling to the surface and squirt of water from washbottle is enough to dislodge like 97+% of it.
However, I never tested this with exposed brass.
I know I am late to this toppic now, but my additional question regarding AP fumes and their control would be - did anyone tried to use 18-20 % HCl for the AP instead of regular tech grade 31 % ?
Thing is - around 20% HCl is azeotrope with water at ambient pressure. It has bp around 120 °C and not much free HCl is evaporated from this mixture without evaporating the water alongside with it. If you will aerate this 20% HCl, much less free HCl vapor will escape for given volume of air pumped in than if you used 30 % or even concentrated 35-37 % HCl.
With AR, I purposefully operated at lower temperatures from the start to get close to that azeotropic ca 20 % concentration (with bp 120 °C) and only then start to heat the mixture to save HCl I put in - as NOx outgas will carry away also HCl fumes, and this is significant past 80 °C. It worked for me and saved HCl could be measured.
*Edited in italic
Thing is - around 20% HCl is azeotrope with water at ambient pressure. It has bp around 120 °C and not much free HCl is evaporated from this mixture without evaporating the water alongside with it. If you will aerate this 20% HCl, much less free HCl vapor will escape for given volume of air pumped in than if you used 30 % or even concentrated 35-37 % HCl.
With AR, I purposefully operated at lower temperatures from the start to get close to that azeotropic ca 20 % concentration (with bp 120 °C) and only then start to heat the mixture to save HCl I put in - as NOx outgas will carry away also HCl fumes, and this is significant past 80 °C. It worked for me and saved HCl could be measured.
*Edited in italic
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I would like to hear more about this. I have noticed sometimes AP seemed to loose more volume than others but mainly attributed it to heat since out weather can change suddenly and drastically at times.
