haveagojoe
Well-known member
- Joined
- Aug 1, 2014
- Messages
- 70
For Etoyin, in response to this previous thread: https://goldrefiningforum.com/threads/please-i-need-your-advise-help.35298/page-2#post-381886
For the "AP" (Copper Chloride) method for recovery of gold foils I do everything with recycled plastic bottles and only use my lab beakers for the refining stages. My method is not really the standard way to do it and probably not the best or right way but I'll describe it anyway.
The way I like to do it is as follows:
In a 500ml plastic bottle I put a handful of bare copper wire, cover it with Hydrochloric acid (so the bottle is about half full), and add a small amount of peroxide - around 10ml or so. I put this somewhere safe with the lid on loosely so that air can get in. After 24hrs the solution will become bright blue-green Copper (II) Chloride solution. This will be my starter solution for the "AP". It doesn't matter that the wire hasn't fully dissolved or if there is white powdery substance forming (Copper (I) Chloride), I can add more Hydrochloric acid to top up the level when I use it, and it will continue to make more starter solution.
I recover the gold from my scrap in separate batches of 3 different types- RAM fingers and clean PCBs; pins and other small parts; and gold plated connectors.
If I have RAM fingers or other clean trimmed PCBs I do them as the first recovery when I have fresh acid. In an empty 5 litre springwater bottle I put the fingers and bits of PCB, add enough hydrochloric acid to cover them completely, and a bit extra, and then add some of my starter solution. It doesn't need much of the starter, just a few glugs to make the Hydrochloric acid in the bottle change colour. I never fill the 5L bottle more than halfway. I use an aquarium air bubbler to bubble air through a tube into the solution. Then I leave it for a few days in a safe well-ventilated place. It's possible to do it without a bubbler but it's a bit slower. It's also possible to do it with the lid screwed on the bottle, but it uses up oxygen from the air inside the bottle so it will crumple the bottle inwards and I have to open the lid each day to let air in. It's better with the lid off.
When I check on it, I take the bubbler tube out, screw the lid on the bottle tightly and shake it up. I should see flakes of gold swirling around in the solution, which by now has turned darker green. If I can see gold still on the fingers I open the lid and leave it another day or two. When I can see all the gold is off the fingers, its time to filter the solution.
I make a transferring funnel out of a 2L plastic bottle by cutting the top part off.
I make a filtering funnel from a plastic bottle which has a long tapered neck like this one:
https://m.media-amazon.com/images/I/31mu-ChA2CL._AC_UF894,1000_QL80_.jpg
I cut it around the base so it keeps maximum volume inside the funnel. I cut a coffee filter into a circle and attach it over the mouth of the funnel using a zip tie. I use the small type of ziptie and pull it nice and tight, and cut off the excess as close as I can.
Then I use another 5L springwater bottle as my filtering collection bottle- there are 2 types of these bottles, ones with a wide mouth and the more common modern ones which have a smaller mouth. For the filtering collection bottle it needs to be the wide mouth type so that the filtering funnel will fit inside, it won't fit in the small mouth type.
So now I'm ready to filter the solution: I put the funnel with the filter attached into the mouth of the collection bottle. I pour some of the "AP" solution into it, very gently and being careful not to knock the funnel or collection bottle over because they are very light when they have nothing in them. (At some point I need to make a stand to hold them steady while I do this). I also have to be careful not to empty any fingers or bits of PCB into the funnel. When I pour the first bit of solution in I've found it's best to do it when it has settled for a few minutes first, and wait til nearly all of it has been filtered before swirling the bottle around to get the foils of gold swirling in the solution for the last few pours. This way is quicker because if the foils are swirling around in the solution when I first start pouring then they clog up the filter at the start and it makes it slow.
When I'm filtering I have to think about the air pressure inside the collection bottle because the tapered neck of the funnel creates a seal against the mouth of the collection bottle. When some of the solution has passed through the filter it will increase the pressure inside the collection bottle, which will slow it down and then stop it from being able to go through, so I occasionally lift the funnel up to allow some air out. If it's slow to filter I can lift the funnel up, squeeze the lower bottle slightly, and then put the funnel back down in the mouth of the bottle again to create a slight vacuum inside the collection bottle which helps to pull the solution through. If the filter gets really clogged up and stops altogether, I hold the funnel down while squeezing the lower bottle gently to force some air up through the filter, which disturbs the foils inside it, making them swirl around again inside the funnel and allowing the solution to continue filtering. Aggitating the funnel carefully can also help. These are quirky techniques I have developed over time and take a bit of practice.
When all the solution is filtered I take the funnel out and cut the ziptie off to retrieve the filter. I do this over a bowl so I don't lose any foils. I use a spray bottle with water to wash the foils out of the filter into my foils collection jar where they can sit and settle. After a day or so when they are settled and the water is clear I use a syringe to remove most of the water so the jar doesn't fill up too much for next time I add to it. I save the filter to process later to catch any gold which remains stuck in it- usually as fine black powder.
So at this point I have some filtered "AP" solution in my 5L filtering collection bottle and some waste bits of PCB in my 5L "AP" bottle. I check the waste to see if there are any foils still in there- usually there are, so I transfer some solution back in with the waste and filter again. When there are no visible foils left, I rinse the waste with some water, which I filter as well, and then empty it out to discard. Or if I have more fingers and PCB scrap somtimes I just throw it in on top of the last batch, it won't be a problem.
After a few batches I will be starting to see white powder building up at the bottom of the solution- this is Copper (I) Chloride, which we don't want because means the solution is saturated with copper. I add some hydrochloric acid to dissolve it back into solution as Copper (II) Chloride which is what gives it the green colour which is how we want it. Sometimes I will pour off most of the solution to use in a new batch before adding hydrochloric to revive the original batch.
If I've got none of the PCB type of scrap left to do, I will move on to pins. Generally people like to separate the magnetic and non-magnetic pins, which is probably a good idea but I don't bother. I just do them all together. I go through the same procedure, using the "AP" solution which has already been used for fingers. By this time it's getting quite dark in colour. After using it on pins it becomes brown-green, almost black. This is because of Iron in the solution forming Ferrous Chloride instead of the Copper Chloride we like. Ferrous Chloride will still eat the copper but it's much slower so after a few times using it on pins I pour it out into a storage bottle. I have quite a few of these bottles of used solution now, so I am currently working on a system to clean it up for reuse using electolysis.
The last batch I do is gold plated items such as connectors. For these I sometimes add peroxide directly into the solution at the start to speed it up, otherwise it's very slow and the acid will start eating away at the underlying metals and forming Ferrous Choride before the foils have been released. The disadvantage of this is that it will dissolve some of the gold into solution- that's ok though because it will cement back out as black powder because of the copper in the connectors, but it makes filtering much slower and more difficult.
I make sure to wear gloves and old clothes the whole time when handling the acid- at 10% it's not very strong so it's not a major emergency if it does get on my skin, but it makes the skin go yellow and needs to be washed off immediately or it will start to burn. Also the contaminants in the solution can be absorbed into the skin which is not good. I always use gloves to avoid it anyway because I found that even after washing it off my hands they still stink of copper. Eye protection is also highly recommended.
I do multiple batches with this method, collecting foils in my jar until I feel like I've collected a good amount. Then I use the syringe to remove as much of the water as I can, and put Hydrochloric acid in there instead. I let them soak in the acid for a few days- if it goes blue or green it means they still have base metals in with them so I replace it with fresh acid until it stays clear. Then I remove the acid and replace it with water again.
Finally I remove as much of the water as possible, transfer the foils to a lab beaker using a spray bottle to rinse the jar out, and place the beaker in a Corningware casserole dish on a portable hob- I do this outdoors not on the kitchen stove! I boil off the remaining water until the foils are dry, and then a bit longer so they get really hot. Then I use a butane torch to get them red hot. This converts any tin which might be present into tin oxide which is soluble in Hydrochloric acid. When they have cooled down completely, I add some Hydrochloric acid and give them a stir, let them settle well, and pour off the acid and refill with water, let them settle again. They are now ready for refining but can be stored like this in water indefinitely.
I might as well describe my approach to the refining stage while I'm at it...
I prefer to use the HCl-Bleach method to put the foils in solution. This process produces Chlorine gas which is noxious- I do this outside but it's better to use a fume hood if you can. I cover the foils with Hydrochloric acid and a little water, then add tiny amounts of bleach while stirring vigourously with a glass rod until they are all dissolved. I leave the solution outside with a loose covering for 24hrs for the Chlorine to evaporate off. Then I add a tiny amount of Sulfuric acid to precipitate any lead which might be present. Then I filter the solution twice through the same filter- I use a glass filtering funnel for this, not the plastic bottle funnel. Then I add a couple of ice cubes, and finally drop the gold out of solution by adding small spoonfuls of Sodium Metabisulfite until white foam appears briefly on the surface and the solution goes dark. I let it settle again for at least 12 hours, the solution should be completely clear with gold powder sitting on the bottom of the beaker. I pour off the solution and dry the gold powder by heating on the hob. This powder can be melted into a solid gold button as it is, but it's better to wash the powder repeatedly by boiling in distilled water, then boil in hydrochloric acid, then distilled water again, and then redissolve it again, filter again and drop it back to powder again. This is how we can get higher purity. Alternatively it can save be saved as powder and mixed with the next batches, and redissolved all together, perhaps dissolving with a different method such as HCl-peroxide or HCl-Nitric acid (Aqua Regia), and a different method to drop it back to powder. This also improves the purity of the final product.
I melt my powder with a MAPP gas torch in a crucible which I glaze first with Borax. I found that butane or propane torches just don't get hot enough, and even MAPP gas takes a long time. Next time I do it I want to try heating the crucible from below at the same time to reduce heat loss.
But for now I just keep on going with my "AP" batches, collecting foils in my jar; and while you read as much as you can and learn about the refining stage, I suggest you do the same.
Etoyin, sorry this turned into a long reply, I got on a roll and thought I might as well try to describe the whole process as best I can. Hopefully others will chime in with comments on my methods. Hope it's useful, good luck, have fun and stay safe!
For the "AP" (Copper Chloride) method for recovery of gold foils I do everything with recycled plastic bottles and only use my lab beakers for the refining stages. My method is not really the standard way to do it and probably not the best or right way but I'll describe it anyway.
The way I like to do it is as follows:
In a 500ml plastic bottle I put a handful of bare copper wire, cover it with Hydrochloric acid (so the bottle is about half full), and add a small amount of peroxide - around 10ml or so. I put this somewhere safe with the lid on loosely so that air can get in. After 24hrs the solution will become bright blue-green Copper (II) Chloride solution. This will be my starter solution for the "AP". It doesn't matter that the wire hasn't fully dissolved or if there is white powdery substance forming (Copper (I) Chloride), I can add more Hydrochloric acid to top up the level when I use it, and it will continue to make more starter solution.
I recover the gold from my scrap in separate batches of 3 different types- RAM fingers and clean PCBs; pins and other small parts; and gold plated connectors.
If I have RAM fingers or other clean trimmed PCBs I do them as the first recovery when I have fresh acid. In an empty 5 litre springwater bottle I put the fingers and bits of PCB, add enough hydrochloric acid to cover them completely, and a bit extra, and then add some of my starter solution. It doesn't need much of the starter, just a few glugs to make the Hydrochloric acid in the bottle change colour. I never fill the 5L bottle more than halfway. I use an aquarium air bubbler to bubble air through a tube into the solution. Then I leave it for a few days in a safe well-ventilated place. It's possible to do it without a bubbler but it's a bit slower. It's also possible to do it with the lid screwed on the bottle, but it uses up oxygen from the air inside the bottle so it will crumple the bottle inwards and I have to open the lid each day to let air in. It's better with the lid off.
When I check on it, I take the bubbler tube out, screw the lid on the bottle tightly and shake it up. I should see flakes of gold swirling around in the solution, which by now has turned darker green. If I can see gold still on the fingers I open the lid and leave it another day or two. When I can see all the gold is off the fingers, its time to filter the solution.
I make a transferring funnel out of a 2L plastic bottle by cutting the top part off.
I make a filtering funnel from a plastic bottle which has a long tapered neck like this one:
https://m.media-amazon.com/images/I/31mu-ChA2CL._AC_UF894,1000_QL80_.jpg
I cut it around the base so it keeps maximum volume inside the funnel. I cut a coffee filter into a circle and attach it over the mouth of the funnel using a zip tie. I use the small type of ziptie and pull it nice and tight, and cut off the excess as close as I can.
Then I use another 5L springwater bottle as my filtering collection bottle- there are 2 types of these bottles, ones with a wide mouth and the more common modern ones which have a smaller mouth. For the filtering collection bottle it needs to be the wide mouth type so that the filtering funnel will fit inside, it won't fit in the small mouth type.
So now I'm ready to filter the solution: I put the funnel with the filter attached into the mouth of the collection bottle. I pour some of the "AP" solution into it, very gently and being careful not to knock the funnel or collection bottle over because they are very light when they have nothing in them. (At some point I need to make a stand to hold them steady while I do this). I also have to be careful not to empty any fingers or bits of PCB into the funnel. When I pour the first bit of solution in I've found it's best to do it when it has settled for a few minutes first, and wait til nearly all of it has been filtered before swirling the bottle around to get the foils of gold swirling in the solution for the last few pours. This way is quicker because if the foils are swirling around in the solution when I first start pouring then they clog up the filter at the start and it makes it slow.
When I'm filtering I have to think about the air pressure inside the collection bottle because the tapered neck of the funnel creates a seal against the mouth of the collection bottle. When some of the solution has passed through the filter it will increase the pressure inside the collection bottle, which will slow it down and then stop it from being able to go through, so I occasionally lift the funnel up to allow some air out. If it's slow to filter I can lift the funnel up, squeeze the lower bottle slightly, and then put the funnel back down in the mouth of the bottle again to create a slight vacuum inside the collection bottle which helps to pull the solution through. If the filter gets really clogged up and stops altogether, I hold the funnel down while squeezing the lower bottle gently to force some air up through the filter, which disturbs the foils inside it, making them swirl around again inside the funnel and allowing the solution to continue filtering. Aggitating the funnel carefully can also help. These are quirky techniques I have developed over time and take a bit of practice.
When all the solution is filtered I take the funnel out and cut the ziptie off to retrieve the filter. I do this over a bowl so I don't lose any foils. I use a spray bottle with water to wash the foils out of the filter into my foils collection jar where they can sit and settle. After a day or so when they are settled and the water is clear I use a syringe to remove most of the water so the jar doesn't fill up too much for next time I add to it. I save the filter to process later to catch any gold which remains stuck in it- usually as fine black powder.
So at this point I have some filtered "AP" solution in my 5L filtering collection bottle and some waste bits of PCB in my 5L "AP" bottle. I check the waste to see if there are any foils still in there- usually there are, so I transfer some solution back in with the waste and filter again. When there are no visible foils left, I rinse the waste with some water, which I filter as well, and then empty it out to discard. Or if I have more fingers and PCB scrap somtimes I just throw it in on top of the last batch, it won't be a problem.
After a few batches I will be starting to see white powder building up at the bottom of the solution- this is Copper (I) Chloride, which we don't want because means the solution is saturated with copper. I add some hydrochloric acid to dissolve it back into solution as Copper (II) Chloride which is what gives it the green colour which is how we want it. Sometimes I will pour off most of the solution to use in a new batch before adding hydrochloric to revive the original batch.
If I've got none of the PCB type of scrap left to do, I will move on to pins. Generally people like to separate the magnetic and non-magnetic pins, which is probably a good idea but I don't bother. I just do them all together. I go through the same procedure, using the "AP" solution which has already been used for fingers. By this time it's getting quite dark in colour. After using it on pins it becomes brown-green, almost black. This is because of Iron in the solution forming Ferrous Chloride instead of the Copper Chloride we like. Ferrous Chloride will still eat the copper but it's much slower so after a few times using it on pins I pour it out into a storage bottle. I have quite a few of these bottles of used solution now, so I am currently working on a system to clean it up for reuse using electolysis.
The last batch I do is gold plated items such as connectors. For these I sometimes add peroxide directly into the solution at the start to speed it up, otherwise it's very slow and the acid will start eating away at the underlying metals and forming Ferrous Choride before the foils have been released. The disadvantage of this is that it will dissolve some of the gold into solution- that's ok though because it will cement back out as black powder because of the copper in the connectors, but it makes filtering much slower and more difficult.
I make sure to wear gloves and old clothes the whole time when handling the acid- at 10% it's not very strong so it's not a major emergency if it does get on my skin, but it makes the skin go yellow and needs to be washed off immediately or it will start to burn. Also the contaminants in the solution can be absorbed into the skin which is not good. I always use gloves to avoid it anyway because I found that even after washing it off my hands they still stink of copper. Eye protection is also highly recommended.
I do multiple batches with this method, collecting foils in my jar until I feel like I've collected a good amount. Then I use the syringe to remove as much of the water as I can, and put Hydrochloric acid in there instead. I let them soak in the acid for a few days- if it goes blue or green it means they still have base metals in with them so I replace it with fresh acid until it stays clear. Then I remove the acid and replace it with water again.
Finally I remove as much of the water as possible, transfer the foils to a lab beaker using a spray bottle to rinse the jar out, and place the beaker in a Corningware casserole dish on a portable hob- I do this outdoors not on the kitchen stove! I boil off the remaining water until the foils are dry, and then a bit longer so they get really hot. Then I use a butane torch to get them red hot. This converts any tin which might be present into tin oxide which is soluble in Hydrochloric acid. When they have cooled down completely, I add some Hydrochloric acid and give them a stir, let them settle well, and pour off the acid and refill with water, let them settle again. They are now ready for refining but can be stored like this in water indefinitely.
I might as well describe my approach to the refining stage while I'm at it...
I prefer to use the HCl-Bleach method to put the foils in solution. This process produces Chlorine gas which is noxious- I do this outside but it's better to use a fume hood if you can. I cover the foils with Hydrochloric acid and a little water, then add tiny amounts of bleach while stirring vigourously with a glass rod until they are all dissolved. I leave the solution outside with a loose covering for 24hrs for the Chlorine to evaporate off. Then I add a tiny amount of Sulfuric acid to precipitate any lead which might be present. Then I filter the solution twice through the same filter- I use a glass filtering funnel for this, not the plastic bottle funnel. Then I add a couple of ice cubes, and finally drop the gold out of solution by adding small spoonfuls of Sodium Metabisulfite until white foam appears briefly on the surface and the solution goes dark. I let it settle again for at least 12 hours, the solution should be completely clear with gold powder sitting on the bottom of the beaker. I pour off the solution and dry the gold powder by heating on the hob. This powder can be melted into a solid gold button as it is, but it's better to wash the powder repeatedly by boiling in distilled water, then boil in hydrochloric acid, then distilled water again, and then redissolve it again, filter again and drop it back to powder again. This is how we can get higher purity. Alternatively it can save be saved as powder and mixed with the next batches, and redissolved all together, perhaps dissolving with a different method such as HCl-peroxide or HCl-Nitric acid (Aqua Regia), and a different method to drop it back to powder. This also improves the purity of the final product.
I melt my powder with a MAPP gas torch in a crucible which I glaze first with Borax. I found that butane or propane torches just don't get hot enough, and even MAPP gas takes a long time. Next time I do it I want to try heating the crucible from below at the same time to reduce heat loss.
But for now I just keep on going with my "AP" batches, collecting foils in my jar; and while you read as much as you can and learn about the refining stage, I suggest you do the same.
Etoyin, sorry this turned into a long reply, I got on a roll and thought I might as well try to describe the whole process as best I can. Hopefully others will chime in with comments on my methods. Hope it's useful, good luck, have fun and stay safe!
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