Okay I joined the site at the beginning of the Year have studied until I cant read anymore which for me is very difficult as I am very dyslexic so reading is not my strong point. Any how to get get to my problem I got quite a few foils from an AP tank I built (thank you Lazer Steve) about 6 grams. I cleaned them well put them in a flask. Covered them with HCL to where I had about a half an inch above the foils. I added about a cap full of clorox. The foils dissolved nicely. I let the container sit in the sun for 24 hours filtered it into anther vessel diluted slightly with water from rinsing the filter. Then to be sure the chlorine had dissipated I heated it in a steam bath for about an hour let it cool to room temp tested it with the home made stannous chloride (again thank you to this form I had this information) The test showed a dark spot on a paper towel as I am slightly color blind it was black to me but may have been a slightly different color. Now here is where I had an issue. I mixed 12 grams of stump out to the solution after a couple of minutes it turned black but failed to precipitate. This was 24 hours ago the solution is now a kinda grey color with no color change on the stannous chloride test. There is a bit of very fine black powder in the bottom . I decided to ask have I screwed op by using the bonide stump out before I went any further or could it be I still have chlorine in my mix.
Fail but why
- Thread starter jtolbert
- Start date
Help Support Gold Refining Forum:
Several possibilities as to why it failed.
1. Stump out comes in several flavors. Check the MSDS online for your brand and make sure it contains bisulfite and not another chemical. Bonide brand is the one I've have found that contains sulfite.
2. Despite your best efforts you have not destroyed the chlorine. From your description, I feel you have, but your reaction says otherwise if you hare using sulfite in 1. above. To be certain the chlorine is gone evaporate the solution to 1/2 of it's volume, filter 100% transparent and free of particulate, then try the sulfite again.
3. You weighed the foils wet and dirty and your tiny bit of black powder is all there is. What was the type and weight of your starting material?
What is your stannous chloride test showing?
Steve
1. Stump out comes in several flavors. Check the MSDS online for your brand and make sure it contains bisulfite and not another chemical. Bonide brand is the one I've have found that contains sulfite.
2. Despite your best efforts you have not destroyed the chlorine. From your description, I feel you have, but your reaction says otherwise if you hare using sulfite in 1. above. To be certain the chlorine is gone evaporate the solution to 1/2 of it's volume, filter 100% transparent and free of particulate, then try the sulfite again.
3. You weighed the foils wet and dirty and your tiny bit of black powder is all there is. What was the type and weight of your starting material?
What is your stannous chloride test showing?
Steve
My starting material was from pins I didn't weigh it before I started but it took about a week to get the 6 grams of what I thought was clean foils since I posted this I did reduce the solution further added more stump out and gained what looks to be at a guess about 4 grams but it is all black so I am thinking I didn't clean my foils sufficiently prior to dissolving them my biggest concern is the powder is so fine just picking up the container causes the bottom of the solution to get cloudy it looks as though it would pass through my filters (coffee filters) I got concerned and posted prematurely but this is my first attempt and I thought I messed up which I did but not as bad as I thought. I didn't measure the Clorox I just splashed a bit in there which I thought was only a cap full but I would bet it was more judging my reaction. The one thing I don't understand why I got a negative stannous test could the excessive chlorine cause this or could tin in the solution which is why I am guessing my precipitate is dirty? I apologize for the premature post and thank you for your advise I do value it.
Several things come to my mind here,
Chlorine is an oxidizer it is what oxidizes the gold (chlorine takes an electron form the gold) the gold Au+ then combines with the chlorides Cl- in solution Au+ (+) 3 Cl- to form AuCl3 gold chloride in solution. (In this reaction the chlorine is reduced (taking the electron from the gold, chlorine gains the electron).
The stannous chloride will reduce the gold back to elemental metal, (reducing the gold, giving the gold back the electrons), in this solution gold metal will not precipitate and becomes a colloidal gold which stays in solution the fine gold colloids reflect light to give the violet color we see in this test, the stannous to be positive in the test for gold must be able to reduce the gold (reduce to give gold back electrons), this means there first has to be gold in the solution we are testing with, and the stannous chloride must be able to reduce this gold,
This will not work if we have an oxidizer like free chlorine in solution taking back the electrons from our gold as the stannous is trying to give our gold back electrons.
Precipitating the gold is similar, we have to give gold back electrons, for the gold to precipitate out of solution as fine metal brown gold powder, if we have an oxidizer in solution it will take electrons away from our gold, and the chemical we are using (like SMB or SO2 gas) which is trying to give electrons to the gold, will be fighting with the chlorine taking the electrons back away from the gold, so gold metal will not form and precipitate as metal gold until the oxidizer is removed from the reaction.
Dirty solution can also make recovery difficult, It sounds as though you removed most of the metals but may not have removed all of them, this and excess chlorine may have compounded the problem just a little.
You may have had to add excess SMB to try and overcome the reaction and eliminate or use up chlorine, this excess SMB will also begin to reduce the copper in solution the gold and copper kind of plating or sticking to each other can be held in solution longer, and when they do settle, can do so as the black powder you see.
Tin the real trouble when dealing with electronic scrap this metal is a thief when dissolved in solution with gold.
As we discussed above when we used the stannous chloride to test for gold we said the stannous chloride reduces the gold to metal, but the gold will not settle it makes fine gold powders suspended in solution as colloidal gold, these small flake of gold hold both charges positive and negative, the keep repelling each other in solution, keeping the fine gold powders from coming together and settling out of solution, robbing you of your gold if you toss out the solution to your waste bucket, another problem here is if we try to test this solution for gold with a stannous chloride test, it can just test negative for gold, as these colloids floating around in solution, are already reduced to metal, this means the stannous cannot work to reduce them and give you the positive purple color, fooling you into thinking you do not have gold in solution, so you throw your gold into the waste bucket, and leaving you scratching your head wonder what is happening to all of that gold you have been dissolving.
I rarely filter much of anything but clear solutions, or solutions that refuse to settle, I let solutions settle over night or sometimes days or weeks, then decant solutions and filter this decanted liquid, I use suction tools to move solutions, a suction bulb and a pipette, or siphoning hoses for buckets.
I can do this without disturbing the settled powders.
Let what gold will settle do so, test with your stannous chloride, when no gold in solution (once you get the excess chlorine problem solved and the gold to precipitate), siphon off the clear liquid from the powders, through a filter into another clean jar.
If this solution filters easily it is unlikely you have a problem with tin (or colloidal gold in solution), but if this solution refuses to filter like it should then you defiantly should suspect tin and colloidal gold being locked up in solution.
If the colloidal gold is not too bad, sometimes the colloids can be broken with a strong sulfuric acid solution and a high heat, just under boiling, this acidifies the solution, drives of HCl on concentrating and can help to break the bond of the collided gold particles, keep solution concentrated and let cool and see if gold settles.
Other times when solution is very dirty and too much tin the sulfuric acid boil will not work to break the colloid, keep solution acidic as possible and do not dilute (dilute or less acidic solutions make filtering tougher), what I try to do is separate solution and particles as much as possible, a coarse filter in a fiberglass Charmin plug in a funnel, then a paper filter letting the solution try to drip through the filter all day if needed, sometimes having to decant solution to an new filter to continue
, Once filtered the Charmin plug and filter are combined for an incineration later, the solution is evaporated to dry salts, the filter paper and plug added the lot is dried and crushed and kept crushed as powders are brought up to red hot and kept red hot stirring the crushed powder to oxidize them giving them time to get completely oxidized, then cooled washed in a water boil, lower heat let powders settle and decant solution, add HCl, bring to a boil, keep boiling letting acid concentrate some, lower heat add a tiny bit of water (not too much tins slats are removed better if not too dilute), let powders settle well decant with solution still very warm, add water and boil, lower heat, but keep solution as hot as possible but still giving time for gold to settle well decant hot to remove lead chloride and other salts soluble in the hot water
if this liquid wash repeat till hot water washes comes off clear indicating no more dissolved metals salts are being removed.
As you can see it is much easier to deal with tin in the pretreatment stages, removing it mechanically or in hot soaking in HCl washes, than it is after you have gold into solution with it.
do not let my post here scare you it does not sound like your solution is this bad, many times when I post something it is not only a response to the person I am talking with but also to try and help explain things to other members who may read it.
When you filter will be your clue.
Chlorine is an oxidizer it is what oxidizes the gold (chlorine takes an electron form the gold) the gold Au+ then combines with the chlorides Cl- in solution Au+ (+) 3 Cl- to form AuCl3 gold chloride in solution. (In this reaction the chlorine is reduced (taking the electron from the gold, chlorine gains the electron).
The stannous chloride will reduce the gold back to elemental metal, (reducing the gold, giving the gold back the electrons), in this solution gold metal will not precipitate and becomes a colloidal gold which stays in solution the fine gold colloids reflect light to give the violet color we see in this test, the stannous to be positive in the test for gold must be able to reduce the gold (reduce to give gold back electrons), this means there first has to be gold in the solution we are testing with, and the stannous chloride must be able to reduce this gold,
This will not work if we have an oxidizer like free chlorine in solution taking back the electrons from our gold as the stannous is trying to give our gold back electrons.
Precipitating the gold is similar, we have to give gold back electrons, for the gold to precipitate out of solution as fine metal brown gold powder, if we have an oxidizer in solution it will take electrons away from our gold, and the chemical we are using (like SMB or SO2 gas) which is trying to give electrons to the gold, will be fighting with the chlorine taking the electrons back away from the gold, so gold metal will not form and precipitate as metal gold until the oxidizer is removed from the reaction.
Dirty solution can also make recovery difficult, It sounds as though you removed most of the metals but may not have removed all of them, this and excess chlorine may have compounded the problem just a little.
You may have had to add excess SMB to try and overcome the reaction and eliminate or use up chlorine, this excess SMB will also begin to reduce the copper in solution the gold and copper kind of plating or sticking to each other can be held in solution longer, and when they do settle, can do so as the black powder you see.
Tin the real trouble when dealing with electronic scrap this metal is a thief when dissolved in solution with gold.
As we discussed above when we used the stannous chloride to test for gold we said the stannous chloride reduces the gold to metal, but the gold will not settle it makes fine gold powders suspended in solution as colloidal gold, these small flake of gold hold both charges positive and negative, the keep repelling each other in solution, keeping the fine gold powders from coming together and settling out of solution, robbing you of your gold if you toss out the solution to your waste bucket, another problem here is if we try to test this solution for gold with a stannous chloride test, it can just test negative for gold, as these colloids floating around in solution, are already reduced to metal, this means the stannous cannot work to reduce them and give you the positive purple color, fooling you into thinking you do not have gold in solution, so you throw your gold into the waste bucket, and leaving you scratching your head wonder what is happening to all of that gold you have been dissolving.
I rarely filter much of anything but clear solutions, or solutions that refuse to settle, I let solutions settle over night or sometimes days or weeks, then decant solutions and filter this decanted liquid, I use suction tools to move solutions, a suction bulb and a pipette, or siphoning hoses for buckets.
I can do this without disturbing the settled powders.
Let what gold will settle do so, test with your stannous chloride, when no gold in solution (once you get the excess chlorine problem solved and the gold to precipitate), siphon off the clear liquid from the powders, through a filter into another clean jar.
If this solution filters easily it is unlikely you have a problem with tin (or colloidal gold in solution), but if this solution refuses to filter like it should then you defiantly should suspect tin and colloidal gold being locked up in solution.
If the colloidal gold is not too bad, sometimes the colloids can be broken with a strong sulfuric acid solution and a high heat, just under boiling, this acidifies the solution, drives of HCl on concentrating and can help to break the bond of the collided gold particles, keep solution concentrated and let cool and see if gold settles.
Other times when solution is very dirty and too much tin the sulfuric acid boil will not work to break the colloid, keep solution acidic as possible and do not dilute (dilute or less acidic solutions make filtering tougher), what I try to do is separate solution and particles as much as possible, a coarse filter in a fiberglass Charmin plug in a funnel, then a paper filter letting the solution try to drip through the filter all day if needed, sometimes having to decant solution to an new filter to continue
, Once filtered the Charmin plug and filter are combined for an incineration later, the solution is evaporated to dry salts, the filter paper and plug added the lot is dried and crushed and kept crushed as powders are brought up to red hot and kept red hot stirring the crushed powder to oxidize them giving them time to get completely oxidized, then cooled washed in a water boil, lower heat let powders settle and decant solution, add HCl, bring to a boil, keep boiling letting acid concentrate some, lower heat add a tiny bit of water (not too much tins slats are removed better if not too dilute), let powders settle well decant with solution still very warm, add water and boil, lower heat, but keep solution as hot as possible but still giving time for gold to settle well decant hot to remove lead chloride and other salts soluble in the hot water
if this liquid wash repeat till hot water washes comes off clear indicating no more dissolved metals salts are being removed.
As you can see it is much easier to deal with tin in the pretreatment stages, removing it mechanically or in hot soaking in HCl washes, than it is after you have gold into solution with it.
do not let my post here scare you it does not sound like your solution is this bad, many times when I post something it is not only a response to the person I am talking with but also to try and help explain things to other members who may read it.
When you filter will be your clue.
Thank you Butcher I am thinking I rushed things a bit thus I had dirty solution compounded by an excess of chlorine this is a lesson I will not have to relearn but in regards to the failed solution I intend to put it in a glass jar on my window sill in my shed where I do all of my work as reminder don't be in a hurry. After I recover what I can of course.
I also would like to thank everyone whom has contributed to this site there is a lot of information here and with out it I would be lost. I started learning about the process to recover metals from electronics on YouTube and by reading what I could on the net. Now as all of you well know a good bit of the stuff on YouTube only gives you enough info to hurt yourself. Fortunately most of the acids used I was already familiar with from work so I knew better but I can just imagine there are prob a few folks out there whom didn't know better hopefully they find there way to the form before they try those experiments.
I have about two pounds of fingers in an AP tank now. I will post my results with photos this time when complete.
I also would like to thank everyone whom has contributed to this site there is a lot of information here and with out it I would be lost. I started learning about the process to recover metals from electronics on YouTube and by reading what I could on the net. Now as all of you well know a good bit of the stuff on YouTube only gives you enough info to hurt yourself. Fortunately most of the acids used I was already familiar with from work so I knew better but I can just imagine there are prob a few folks out there whom didn't know better hopefully they find there way to the form before they try those experiments.
I have about two pounds of fingers in an AP tank now. I will post my results with photos this time when complete.
Fingers are a great material to work with, A great learning tool, they are also good to use with Hokes book doing a few of her Experiments (like testing for values in solution)
You can also come up with your own experiments like Hoke teaches to give you a better idea, how metals react, like how tin from solder in solution of gold can rob you of your gold.
In a few test tubes try this put a few ml of AuCl3 in each, now add several drops of stannous chloride, to one test tube, test each of these for gold with stannous chloride and a Q-tip, now add SMB to the second test tube, and ferrous sulfate to the third, now test the solutions again, now try to precipitate the gold from the test tube with tin in it, see if you get the same amount of gold.
You can also come up with your own experiments like Hoke teaches to give you a better idea, how metals react, like how tin from solder in solution of gold can rob you of your gold.
In a few test tubes try this put a few ml of AuCl3 in each, now add several drops of stannous chloride, to one test tube, test each of these for gold with stannous chloride and a Q-tip, now add SMB to the second test tube, and ferrous sulfate to the third, now test the solutions again, now try to precipitate the gold from the test tube with tin in it, see if you get the same amount of gold.
Thank you Butcher I will try that. I am guessing what the result will be. I am just glad I was able to get a bit more than half of the gold from my screwed up batch. I was curious I have a few Motorola mobile bases there looks to be some parts which are gold not plated but they have a ton of silver solder on them and a porcelain button attached on both sides I am trying to decide what would be the best way to attack them I have source to get a ton of them if I can figure out the best way to treat them any Ideas
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Alentia
Well-known member
I have tried to fight Sn by boiling some electronic components with NaOH. The reaction is somewhat very slow and not much of Sn converted into Stannous Hydroxide. However what it does, it separates glass from gold foils in Pentium CPUs, which usually remain unprocessed by AR alone without NaOH treatment.
On the topic. I have tried HCL/Clorox several times now on different test foils and did not have any encouraging results so far. Several times I got white sediment at the bottom after precipitation either with SMB or Copperas. Adding small amount of AR into white sediment dissolve micro particles of gold hidden inside the "white stuff" and after that, precipitation works as normal.
Twice I got pink powder as precipitant. Further dissolving in AR, filtering while leaving white sediment behind, gold drops as normal.
I did try boiling solution to expel chlorine. Tried to bring pH to 5 with NaCO3 and/or NaOH. It does not seems I am getting any good results. So far AR is much better and cleaner choice. Stannous is always negative for my HCL/Clorox, but eventually I get my gold out of the solution.
It would be great if someone with great experience with HCL/Clorox method can post some empirical data as well as "do and donts".
The advantage of HCL/Clorox is the ability to process right in the plastic bucket, while AR requires glass vessel.
On the topic. I have tried HCL/Clorox several times now on different test foils and did not have any encouraging results so far. Several times I got white sediment at the bottom after precipitation either with SMB or Copperas. Adding small amount of AR into white sediment dissolve micro particles of gold hidden inside the "white stuff" and after that, precipitation works as normal.
Twice I got pink powder as precipitant. Further dissolving in AR, filtering while leaving white sediment behind, gold drops as normal.
I did try boiling solution to expel chlorine. Tried to bring pH to 5 with NaCO3 and/or NaOH. It does not seems I am getting any good results. So far AR is much better and cleaner choice. Stannous is always negative for my HCL/Clorox, but eventually I get my gold out of the solution.
It would be great if someone with great experience with HCL/Clorox method can post some empirical data as well as "do and donts".
The advantage of HCL/Clorox is the ability to process right in the plastic bucket, while AR requires glass vessel.
patnor1011
Well-known member
To get 4-6g of gold from computer pins will take a lot of them to dissolve. If you have the best of the best you still will have to process well over pound, I would say close to kilogram.
I had about two pounds give or take I didn't weigh them I have anther batch of a little over 3 pounds I am going to do after I get done with the about two pounds of fingers I am doing now I also just acquired 89 cell phones I have been gathering these materials for a while now
Butcher I read somewhere I can not remember where but the jest of the article was if you have problem such as I did (do) with dirty solution was to heavily dilute then place in an open container in the sun allow the sun to evaporate the solution to salt then boil in hcl as remove the contaminates dissolve values again and precipitate as usual what are your thoughts on this to me it does not seem like it would work but I am a noob at this
If you have tin in solution you do not want it dilute, the problem just gets worse, and you have more of it to deal with. Tin is just a bit easier to deal with in strongly acidic concentrated solution, and a little bit easier if Hot as well.
First did you filter the solution? How did it run through the filter easy, all day, not at all?
If you cannot filter you have too much tin and this will not work
If you were able to filter the solution, heat it up, you do not need it boiling but I would heat it till it steams good, if you had a lot of extra water, then evaporate off the extra water, hydrochloric acid HCl is an acid sodium hypochlorite NaClO is a base, these will neutralize each other and will form sodium chloride NaCl in the reaction, so if we drive off too much water we can see salts form these are not really a problem as NaCl is water soluble, but our goal here is to just get rid of free chlorine we do not need to concentrate solution to salt, if we have silver or lead they will also form white salts, but we can also deal with these if they show up. After you heated the solution to vapor off possible free chlorine, turn off heat let cool, filter into a clean jar cover the solution and let it sit overnight, you may see gold and salts in the morning, or salts and no brown gold, decant solution and do a stannous test, if positive, you can try just a little more SMB to precipitate the gold.
If the solution is dirty with base metals and trash it is pretty bad, but gold can be cemented out of solution using copper.
But the real problem is tin, the tin reduces the gold to metal that will not settle, you cannot cement it onto copper because the gold is already reduced to metal, so copper will not reduce it, the gold is locked up in solution as a colloid, very fine particles of metallic gold with opposite polarity's repelling each other keeping itself moving around, just floating around in solution, it will be very hard to filter, if there is very much tin in your solution, you will know it, you will not be able to filter the solution, the gold is fine enough to try and go through the filter, but a lot of it is also trapped with the tin that does not want to go through a filter, so even filtering it you can have gold in the filter and in the solution, if you find this is your problem read the post above again.
The best way to deal with much tin and gold is to get it into a state so that you can incinerate it glowing red hot in an oxidizing atmosphere, to oxidize the tin which can be removed from the gold with a boil in HCl.
First did you filter the solution? How did it run through the filter easy, all day, not at all?
If you cannot filter you have too much tin and this will not work
If you were able to filter the solution, heat it up, you do not need it boiling but I would heat it till it steams good, if you had a lot of extra water, then evaporate off the extra water, hydrochloric acid HCl is an acid sodium hypochlorite NaClO is a base, these will neutralize each other and will form sodium chloride NaCl in the reaction, so if we drive off too much water we can see salts form these are not really a problem as NaCl is water soluble, but our goal here is to just get rid of free chlorine we do not need to concentrate solution to salt, if we have silver or lead they will also form white salts, but we can also deal with these if they show up. After you heated the solution to vapor off possible free chlorine, turn off heat let cool, filter into a clean jar cover the solution and let it sit overnight, you may see gold and salts in the morning, or salts and no brown gold, decant solution and do a stannous test, if positive, you can try just a little more SMB to precipitate the gold.
If the solution is dirty with base metals and trash it is pretty bad, but gold can be cemented out of solution using copper.
But the real problem is tin, the tin reduces the gold to metal that will not settle, you cannot cement it onto copper because the gold is already reduced to metal, so copper will not reduce it, the gold is locked up in solution as a colloid, very fine particles of metallic gold with opposite polarity's repelling each other keeping itself moving around, just floating around in solution, it will be very hard to filter, if there is very much tin in your solution, you will know it, you will not be able to filter the solution, the gold is fine enough to try and go through the filter, but a lot of it is also trapped with the tin that does not want to go through a filter, so even filtering it you can have gold in the filter and in the solution, if you find this is your problem read the post above again.
The best way to deal with much tin and gold is to get it into a state so that you can incinerate it glowing red hot in an oxidizing atmosphere, to oxidize the tin which can be removed from the gold with a boil in HCl.
The easiest way to deal with Tin is to remove it first with incineration and HCl. If you are not sure if Tin is present in a particular type of scrap, process a small test sample to find out.
When your test produces a thick white paste, jelly, or extremely hard to filter sludge, your scrap has Tin in it that needs to be removed before you use any form of nitric acid on the scrap. It's much easier to take the time to remove the Tin first, then to deal with the metastannic acid after the nitric acid has been added. Warm dilute sulfuric acid or muriatic acid is a great way to remove tin from your scrap before proceeding to reagents which involve nitric acid (AR and 50/50 nitric acid).
Steve
When your test produces a thick white paste, jelly, or extremely hard to filter sludge, your scrap has Tin in it that needs to be removed before you use any form of nitric acid on the scrap. It's much easier to take the time to remove the Tin first, then to deal with the metastannic acid after the nitric acid has been added. Warm dilute sulfuric acid or muriatic acid is a great way to remove tin from your scrap before proceeding to reagents which involve nitric acid (AR and 50/50 nitric acid).
Steve
