mikeinkaty
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Has anyone measured the amount of copper used when dropping silver that was disolved with Nitric Acid? I've tried 4 different searches and can't find that tidbit.
Mike
Mike
Copper consumption
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mjgraham
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I don't know for sure but I do remember someone saying they had 500g of silver and someone mentioned like 167g of copper, I guess it depends on free nitric to. So it looks like 1/3 the amount of copper for silver, although I hope some one can clear it up.
mikeinkaty said:
I believe this thread discusses nitric acid consumption of copper: http://goldrefiningforum.com/phpBB3/viewtopic.php?f=50&t=16714
GSP gives us these numbers:
To dissolve a gram of silver, it takes approximately 1.2 ml of 70% nitric acid, and 1.2 ml water (50:50% solution).
It takes approximately 3.4 times more nitric acid to dissolve copper than it does to dissolve silver.
One gram of copper will cement about 3.4 grams of silver, (if excess nitric acid more copper would be dissolved until the free nitric acid is consumed).
To dissolve a gram of silver, it takes approximately 1.2 ml of 70% nitric acid, and 1.2 ml water (50:50% solution).
It takes approximately 3.4 times more nitric acid to dissolve copper than it does to dissolve silver.
One gram of copper will cement about 3.4 grams of silver, (if excess nitric acid more copper would be dissolved until the free nitric acid is consumed).
mikeinkaty
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butcher said:
Thanks Butcher, etal.
I estimate I've used about 3 lbs of copper so far and I'm about 75% done. So, these figures jive pretty well with what I've observed.
Also, I have a lot of copper fittings with solder on them. Is there any acid that will disolve the solder but not the copper?
Mike
If it is a lead solder HCl may break it down, but I wouldn’t mess with it, (tin trouble).
If it were silver solder (and I was going to use the cemented silver for in-quartering gold) then I would consider using it as is.
Maybe you have some old silver plated copper bowl; you were wondering how to de-plate.
It sounds like you only need about a pound of copper; can you cut off the solder portion and just use the clean parts?
Or maybe take some of your other scrap metal to your junkyard and trade it for some big bars of copper?
If you knew how much copper for sure, you could add a portion of that copper as very fine wire.
If you scrap electronics, you should have a pile of transformers, grab some of these, cut the welds on the iron laminate, and pull them apart (my preference) un-wind copper wire.
Put iron laminate in plastic bag to save it to make ferrous sulfate with later.
Or you can take a chisel and cut copper coil pull out copper with needle nose pliers (not my preference wires are short and harder to get clean).
Torch the very fine copper wire with a torch to burn off shellac, rinse with water, form a very loose ball of copper wire, these can be used to cement silver from solution, the finer the wire the better, I will use these normally early in the cementing process hanging them in solution with a larger piece of bent copper wire (with crushing stirring and sometimes screening during the process if needed), to insure the fine copper wire is completely consumed, and not just coated with silver, I will finish up the process with a thick bar of clean copper.
Note the larger thicker the bar of clean copper the better your silver will come out, (if copper is not consumed), you do not want small pieces of undissolved copper meal in your silver if you can help it.
If it were silver solder (and I was going to use the cemented silver for in-quartering gold) then I would consider using it as is.
Maybe you have some old silver plated copper bowl; you were wondering how to de-plate.
It sounds like you only need about a pound of copper; can you cut off the solder portion and just use the clean parts?
Or maybe take some of your other scrap metal to your junkyard and trade it for some big bars of copper?
If you knew how much copper for sure, you could add a portion of that copper as very fine wire.
If you scrap electronics, you should have a pile of transformers, grab some of these, cut the welds on the iron laminate, and pull them apart (my preference) un-wind copper wire.
Put iron laminate in plastic bag to save it to make ferrous sulfate with later.
Or you can take a chisel and cut copper coil pull out copper with needle nose pliers (not my preference wires are short and harder to get clean).
Torch the very fine copper wire with a torch to burn off shellac, rinse with water, form a very loose ball of copper wire, these can be used to cement silver from solution, the finer the wire the better, I will use these normally early in the cementing process hanging them in solution with a larger piece of bent copper wire (with crushing stirring and sometimes screening during the process if needed), to insure the fine copper wire is completely consumed, and not just coated with silver, I will finish up the process with a thick bar of clean copper.
Note the larger thicker the bar of clean copper the better your silver will come out, (if copper is not consumed), you do not want small pieces of undissolved copper meal in your silver if you can help it.
its very simple guys
copper atomic weight - 63,56 g . mole -1
silver atomic weight - 107,87 g . mole -1
reaction that occurs in silver cementing
2 AgNO3 + Cu -----> Cu (NO3)2 + 2Ag
this equation says that 1 Mole of Cu is able to push out 2 moles of Ag
(2 x 107,87 ) / 63,56 = 3, 394
1 g of copper is able to push out almost 3,4 g of silver from nitrate solution at optimal conditions
copper atomic weight - 63,56 g . mole -1
silver atomic weight - 107,87 g . mole -1
reaction that occurs in silver cementing
2 AgNO3 + Cu -----> Cu (NO3)2 + 2Ag
this equation says that 1 Mole of Cu is able to push out 2 moles of Ag
(2 x 107,87 ) / 63,56 = 3, 394
1 g of copper is able to push out almost 3,4 g of silver from nitrate solution at optimal conditions
mikeinkaty
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Butcher, I have pleanty of clean copper. Have probably 5 lbs of the used fittings and was wondering about them.
mike
mike
Sucho,
Thanks for that formula, and working out the math.
Mike,
Maybe you can trade a pile of the soldered portion of copper fittings for copper buss bars from electrical panels at your scrap yard.
With the thicker the bar of copper the less chance of pieces of copper falling off into your silver powders, and the more pure your silver would be in the end, cleaning the bar of copper, and removing oxidation, also helps. if reusing a copper buss bar wash it well and dry it store it in a plastic bag (copper carbonate, the light green oxidation normally seen on copper, from copper oxidation in air does not dissolve well).
I also just noticed I missed including the amount of silver in my post above, I will edit it.
Thanks for that formula, and working out the math.
Mike,
Maybe you can trade a pile of the soldered portion of copper fittings for copper buss bars from electrical panels at your scrap yard.
With the thicker the bar of copper the less chance of pieces of copper falling off into your silver powders, and the more pure your silver would be in the end, cleaning the bar of copper, and removing oxidation, also helps. if reusing a copper buss bar wash it well and dry it store it in a plastic bag (copper carbonate, the light green oxidation normally seen on copper, from copper oxidation in air does not dissolve well).
I also just noticed I missed including the amount of silver in my post above, I will edit it.
mikeinkaty
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Travelling to and from the nearest place I could sell copper would cost more than the value of my copper!
mjgraham
Well-known member
Sucho said:
Thanks for this, going in my notes.
bswartzwelder
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Butcher wrote: If it is a lead solder HCl may break it down, but I wouldn’t mess with it, (tin trouble).
Butcher, I have a lot of solder to remove from cell phone circuit boards. I was going to just give them a boil in HCl. Is there a better way to deal with this?
Butcher, I have a lot of solder to remove from cell phone circuit boards. I was going to just give them a boil in HCl. Is there a better way to deal with this?
HCl will dissolve tin from the solder, leaving the lead as a chloride powder; this can also dissolve metals above Hydrogen in the reactivity series of metal, but will not dissolve copper.
Some heating can help this slow process.
Copper II Chloride (HCl / 3% hydrogen peroxide) (acid peroxide), will also break down solder, the oxygen and bubbles can help the action, this will oxidize metals below Hydrogen in the reactivity series, and can also dissolve base metals like copper, this will also leave insoluble white powders of lead chloride. The lead oxidized by the peroxide to PbO with HCl gives lead chloride and water.
PbO + 2HCl --> PbCl2 + H2O
White powders in chloride solutions can be several metal salts NaCl, CuCl, AgCl, PbCl2.
Sodium chloride NaCl (table salt) is soluble in cold water.
Lead chloride PbCl2 is very insoluble in cold water, but will become very soluble in boiling hot water.
Copper I chloride CuCl is fairly insoluble in cold water, with HCl will be converted to a green solution (brown if concentrated) of soluble copper II chloride solution.
Silver chloride AgCl, insoluble in cold or very hot water (very fluffy at times and can take time to settle), it is also insoluble in HCL (or HNO3), silver chloride when rinsed of the strong acid will darken in light somewhat converting the crystals to silver metal in light giving a violet or gray black color to the salts.
There are also reagents that will dissolve silver chloride (see this in other discussions on the forum).
This gives us a way to determine what our white powder metal salts are, and a way to separate them from each other.
For more information, and a better understanding (and to get some very useful charts or tables) study:
Reactivity series of metals.
Solubility rules.
Search wikipedia documents for the metal salts above.
Some heating can help this slow process.
Copper II Chloride (HCl / 3% hydrogen peroxide) (acid peroxide), will also break down solder, the oxygen and bubbles can help the action, this will oxidize metals below Hydrogen in the reactivity series, and can also dissolve base metals like copper, this will also leave insoluble white powders of lead chloride. The lead oxidized by the peroxide to PbO with HCl gives lead chloride and water.
PbO + 2HCl --> PbCl2 + H2O
White powders in chloride solutions can be several metal salts NaCl, CuCl, AgCl, PbCl2.
Sodium chloride NaCl (table salt) is soluble in cold water.
Lead chloride PbCl2 is very insoluble in cold water, but will become very soluble in boiling hot water.
Copper I chloride CuCl is fairly insoluble in cold water, with HCl will be converted to a green solution (brown if concentrated) of soluble copper II chloride solution.
Silver chloride AgCl, insoluble in cold or very hot water (very fluffy at times and can take time to settle), it is also insoluble in HCL (or HNO3), silver chloride when rinsed of the strong acid will darken in light somewhat converting the crystals to silver metal in light giving a violet or gray black color to the salts.
There are also reagents that will dissolve silver chloride (see this in other discussions on the forum).
This gives us a way to determine what our white powder metal salts are, and a way to separate them from each other.
For more information, and a better understanding (and to get some very useful charts or tables) study:
Reactivity series of metals.
Solubility rules.
Search wikipedia documents for the metal salts above.
mikeinkaty
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Butcher -
Experimenting a little I added 50g gms of table salt to 200 ml of copper nitrate. Filtered off the white percipitate then added aluminum. After the reaction quit I tried to filter it but it immediately plugged up the paper. I quess I could boil it down. Would be interesting to see how much copper dropped out. I guess the white stuff was sodium nitrate? The aluminum was reacting with the copper chloride, dropping copper and making aluminum chloride.
Wonder if I could make nitric acid out of the sodium nitrate? With what I'm now paying for nitric acid there would be no incentive to try.
Mike
Experimenting a little I added 50g gms of table salt to 200 ml of copper nitrate. Filtered off the white percipitate then added aluminum. After the reaction quit I tried to filter it but it immediately plugged up the paper. I quess I could boil it down. Would be interesting to see how much copper dropped out. I guess the white stuff was sodium nitrate? The aluminum was reacting with the copper chloride, dropping copper and making aluminum chloride.
Wonder if I could make nitric acid out of the sodium nitrate? With what I'm now paying for nitric acid there would be no incentive to try.
Mike
Let me guess...
Cu nitrate + Na chloride -> Cu chloride and Na nitrate, CU chloride have a low solubility so some will drop as a white powder.
Copper in solution + aluminum metal -> copper cementing and aluminum in solution. Aluminum in solution can be a mess, very hard to filter. (As I've heard, haven't tried it myself.)
Playing around with chemicals without any plan, are we?
Göran
Cu nitrate + Na chloride -> Cu chloride and Na nitrate, CU chloride have a low solubility so some will drop as a white powder.
Copper in solution + aluminum metal -> copper cementing and aluminum in solution. Aluminum in solution can be a mess, very hard to filter. (As I've heard, haven't tried it myself.)
Playing around with chemicals without any plan, are we?
Göran
I agree with everything that g_axelsson stated, also you have a chloride and nitrate, if even slightly acidic would form a pesuado aqua regia which would dissolve gold, if tin is involed this would give trouble filtering, and if gold went into solution it would colloid, this could become a big mess, the aluminum also form jelly type substance with chlorides.
mikeinkaty
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g_axelsson said:
Yeah, I had read that aluminum would react with copper chloride, dropping the CU and making AL chloride. Wonder how much Na Nitrate I could make with 10 gallons of Cu Nitrate?
Mike
