Method for recovering silver from photo chemicals
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The black could be elemental silver. Although I would expect it to look more gray. You said you dried it in an oven so black would make sense, if the gray silver powder turned black then.
Silver chloride will be white, the white silver chloride will be milky in solution and can form what looks like a white cottage cheese, which can take some time for this fluffy precipitate to settle from solution, to a white powder. If this white powder is washed free of acid and let sit in the sun (or bright light) it will darken to look like a gray, violet or even black as the sun will try to convert some of this salt to elemental silver (photography uses this principle), but you will need to use a reducing method to reduce your silver chloride to metal, as light may work on film, it will not work well with a jar of silver chloride salt, where the light has a hard time being exposed to all of the silver chloride in its crystal structure or where powders do not give good exposure to all of the silver chloride to that light...
Silver chloride will be white, the white silver chloride will be milky in solution and can form what looks like a white cottage cheese, which can take some time for this fluffy precipitate to settle from solution, to a white powder. If this white powder is washed free of acid and let sit in the sun (or bright light) it will darken to look like a gray, violet or even black as the sun will try to convert some of this salt to elemental silver (photography uses this principle), but you will need to use a reducing method to reduce your silver chloride to metal, as light may work on film, it will not work well with a jar of silver chloride salt, where the light has a hard time being exposed to all of the silver chloride in its crystal structure or where powders do not give good exposure to all of the silver chloride to that light...
The cemented silver will be finely divided elemental silver, if this silver was cemented from solution by adjusting pH with Dilute H2SO4 and zinc, (note adding just enough zinc to precipitate the silver), then you should not have much extra zinc in the silver powders, Juan suggested using Dilute HCl to wash any extra zinc from the silver powders checking for bubbles indicating pieces of zinc.
Some of this depends on the size of zinc used, fine powders or shavings , or if larger pieces of zinc or were used, and you added more than necessary, you could have pieces that can be fished out, and removed locating them by the bubbles they form in the dilute acid. fine shavings in abundance will need to be dissolved in the acid wash.
Dilute HCl will dissolve zinc powders, larger pieces of zinc will take longer in the HCl wash which can convert a tiny bit of the fine silver to a silver chloride, normally I would suspect just the surface of some of the silver powder to begin to form a coating of silver chloride if left in the acid for a short period of time after the zinc dissolved, this normally would not be a problem if done properly as I do not think much silver chloride would be formed from a wash, without too much excess, or large pieces of zinc, or where the HCl was diluted as to not attack the silver to much of an extent, but had enough acid to dissolve the much more reactive zinc.
Using too strong of an HCl acid in the wash, leaving the silver in the acid solution for long periods of time, or heating it, the more possibility of coating some of the fine silver with a crust of silver chloride.
Dilute 10% H2SO4 could also be used to wash the zinc and dissolve it, it will also form bubbles to find pieces of zinc, the dilute sulfuric acid will not dissolve elemental silver and will not form any silver chloride.
The silver chloride could have been precipitated from solution as the milky solution, with the addition of HCl (by the way this is a good way to test a small portion of the solution for silver).
With as much milky solution as you show in your photo that is a good possibility, I was assuming you were washing the silver powders, and had already decanted them from the original solution they were cemented from, in which case you would not be precipitating silver chloride from that original solution, as that original solution would have been removed from the silver powder, and the powders washed with water before adding the dilute HCl solution to dissolve the little zinc left in the silver powders.
If you are only washing the silver powder, where you did not have silver in solution, the silver chloride was formed with too strong of an HCl acid wash on the finely divided silver powder.
If you had a solution with silver ions left in it, you would precipitate silver from solution as silver chloride.
I would not expect such a milky solution if you used dilute HCl to wash silver powders just to remove a little zinc, but I did not expect you were washing the silver powder with a solution that still contained silver ions either.
But you obviously did form a lot of silver chloride...
Some of this depends on the size of zinc used, fine powders or shavings , or if larger pieces of zinc or were used, and you added more than necessary, you could have pieces that can be fished out, and removed locating them by the bubbles they form in the dilute acid. fine shavings in abundance will need to be dissolved in the acid wash.
Dilute HCl will dissolve zinc powders, larger pieces of zinc will take longer in the HCl wash which can convert a tiny bit of the fine silver to a silver chloride, normally I would suspect just the surface of some of the silver powder to begin to form a coating of silver chloride if left in the acid for a short period of time after the zinc dissolved, this normally would not be a problem if done properly as I do not think much silver chloride would be formed from a wash, without too much excess, or large pieces of zinc, or where the HCl was diluted as to not attack the silver to much of an extent, but had enough acid to dissolve the much more reactive zinc.
Using too strong of an HCl acid in the wash, leaving the silver in the acid solution for long periods of time, or heating it, the more possibility of coating some of the fine silver with a crust of silver chloride.
Dilute 10% H2SO4 could also be used to wash the zinc and dissolve it, it will also form bubbles to find pieces of zinc, the dilute sulfuric acid will not dissolve elemental silver and will not form any silver chloride.
The silver chloride could have been precipitated from solution as the milky solution, with the addition of HCl (by the way this is a good way to test a small portion of the solution for silver).
With as much milky solution as you show in your photo that is a good possibility, I was assuming you were washing the silver powders, and had already decanted them from the original solution they were cemented from, in which case you would not be precipitating silver chloride from that original solution, as that original solution would have been removed from the silver powder, and the powders washed with water before adding the dilute HCl solution to dissolve the little zinc left in the silver powders.
If you are only washing the silver powder, where you did not have silver in solution, the silver chloride was formed with too strong of an HCl acid wash on the finely divided silver powder.
If you had a solution with silver ions left in it, you would precipitate silver from solution as silver chloride.
I would not expect such a milky solution if you used dilute HCl to wash silver powders just to remove a little zinc, but I did not expect you were washing the silver powder with a solution that still contained silver ions either.
But you obviously did form a lot of silver chloride...
Thank you sir for the reply.
I was washing the cemented silver at the time with HCL, and I was using 15 percent HCL 50cc to 1 liter of distilled water. Sir, how can I dilute the battery acid to use as a wash for the excess zinc? or can I just add boiling water to wash the excess zinc?
Sincerely,
John
I was washing the cemented silver at the time with HCL, and I was using 15 percent HCL 50cc to 1 liter of distilled water. Sir, how can I dilute the battery acid to use as a wash for the excess zinc? or can I just add boiling water to wash the excess zinc?
Sincerely,
John
Hot water will dissolve many salts of metals, but it will not dissolve zinc metal, zinc is a very reactive meta,l and will dissolve in dilute acids easily, the dilute acid containing large amount of water can hold this newly formed, salt of the metal and acid, (such as zinc sulfate).
As far as diluting the sulfuric acid I am sure there are formulas, but I was never concerned with them (unless I need a certain molar solution), I would just get close to the dilution of the acid I wanted, I also normally use heat in most every process, and this has many benefits, like if I get the acid to diluted, the heat just concentrates it as water is vapored off...
Say I am using a sulfuric battery acid which is about 32% I may just use two more parts its volume of water.
Example two parts water one part 32% acid, if I was using concentrated acid I may go with nine parts water and one part acid with a little heat, and stirring.
Other members may have better advice, methods or formulas to get a better percentage of acid (dilution of the acid) concentration than I will normally use, or can give advice on.
I do not think an exact dilution was that important here, as long as it is very dilute, and not very concentrated.
volume percentage = volume of solute/total volume of solution X 100 (to get percentage)...
Concentrated sulfuric especially if heated could form some silver sulfate, silver is such an unreactive metal as long as the sulfuric acid is dilute it will not be attacked by the dilute sulfuric acid...
Note: With sulfuric acid always add the acid to the water.
NEVER ADD WATER TO THE ACID.
Concentrated sulfuric acid is especially dangerous if you do not follow the above rule, the water hitting the concentrated acid makes a steam explosion as the water flash boils, that can splash the concentrated acid all over you giving any uncovered skin terribly acid burns...
As far as diluting the sulfuric acid I am sure there are formulas, but I was never concerned with them (unless I need a certain molar solution), I would just get close to the dilution of the acid I wanted, I also normally use heat in most every process, and this has many benefits, like if I get the acid to diluted, the heat just concentrates it as water is vapored off...
Say I am using a sulfuric battery acid which is about 32% I may just use two more parts its volume of water.
Example two parts water one part 32% acid, if I was using concentrated acid I may go with nine parts water and one part acid with a little heat, and stirring.
Other members may have better advice, methods or formulas to get a better percentage of acid (dilution of the acid) concentration than I will normally use, or can give advice on.
I do not think an exact dilution was that important here, as long as it is very dilute, and not very concentrated.
volume percentage = volume of solute/total volume of solution X 100 (to get percentage)...
Concentrated sulfuric especially if heated could form some silver sulfate, silver is such an unreactive metal as long as the sulfuric acid is dilute it will not be attacked by the dilute sulfuric acid...
Note: With sulfuric acid always add the acid to the water.
NEVER ADD WATER TO THE ACID.
Concentrated sulfuric acid is especially dangerous if you do not follow the above rule, the water hitting the concentrated acid makes a steam explosion as the water flash boils, that can splash the concentrated acid all over you giving any uncovered skin terribly acid burns...
Hi everyone! I tried to melt the cemented silver using the zinc method and here are the results.
I have some few questions. When I was melting the cemented silver using the zinc method, I got this metal that is hard to melt, but i did maage to melt some silver though. Is this hard to melt metal the left over zinc?
I guess the next step for me is to refine the silver using nitric acid and puting copper to ceent the silver out again. But i have a worry though. I found something in youtube about nitric acid and powdered zinc combined which burst into flames!
Any comments anyone?
Thank you
John
I have some few questions. When I was melting the cemented silver using the zinc method, I got this metal that is hard to melt, but i did maage to melt some silver though. Is this hard to melt metal the left over zinc?
I guess the next step for me is to refine the silver using nitric acid and puting copper to ceent the silver out again. But i have a worry though. I found something in youtube about nitric acid and powdered zinc combined which burst into flames!
Any comments anyone?
Thank you
John
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rickbb
Well-known member
If it was done properly you shouldn't have any "left over zinc".
The zinc will dissolve and replace the silver in the fixer, unless you use way to much, then you can have some zinc in with the precipitated silver.
One thing I've learned about you tube videos, unless they were made by one of the forum members here, they aren't worth watching.
The zinc will dissolve and replace the silver in the fixer, unless you use way to much, then you can have some zinc in with the precipitated silver.
One thing I've learned about you tube videos, unless they were made by one of the forum members here, they aren't worth watching.
I'm bit confused now. At the start Ignatz61 said that he has mixture of fixer and developer and it seams to me that people have forgotten that as they only mention fixer in their advices. The mixture was alkaline so maybe that fixer was in fact blix. I'm wondering now is there a difference in processing (chemically or electrolytically) pure fix or blix in contrast to fix/blix mixed with developer. I have learned quite a lot about pure fix/blix processing from this forum but I can't find anything about daily spend chemical mixture processing.
rickbb
Well-known member
Photo processers do not mix the developer and fix, maybe someone who didn't quite understand the process dumped them in together.
Blix is used in processing color film/prints and it stands for bleach/fix, (not the same kind of bleach you have at home), and also does not, (normally), contain developer.
Spent developer does not contain any silver, none, and is of no value. Mixing it in with fix only complicates things and makes a stink and it can release a form of chlorine gas if you have more developer than fixer.
We only discuss recovering silver from spent fixer, (or blix if it was a color process, rare now days), because that is where the silver is. The added developer will slow down recovery but he should still be able to make it work.
If you have a source for spent photo processing chemicals, only collect the fix, let them dispose of the developer according to their local regulations.
Blix is used in processing color film/prints and it stands for bleach/fix, (not the same kind of bleach you have at home), and also does not, (normally), contain developer.
Spent developer does not contain any silver, none, and is of no value. Mixing it in with fix only complicates things and makes a stink and it can release a form of chlorine gas if you have more developer than fixer.
We only discuss recovering silver from spent fixer, (or blix if it was a color process, rare now days), because that is where the silver is. The added developer will slow down recovery but he should still be able to make it work.
If you have a source for spent photo processing chemicals, only collect the fix, let them dispose of the developer according to their local regulations.
Thank you rickbb for your reply. I said i have read this forum (quite thoroughly) so I know things you are saying to me.
Now they (photo studio) are collecting all chemicals in one bucket so that is why I'm asking the above stated question. They fill machine up and it does all the job. It may not mix developer and blix in the developing process but it may do so in discarding (of chemicals) process. The thing is I don't know if developing machine has separate drain for blix and developer or just one so it would be impossible to collect blix separately.
If it is possible of course I would ask them to do so.
Now they (photo studio) are collecting all chemicals in one bucket so that is why I'm asking the above stated question. They fill machine up and it does all the job. It may not mix developer and blix in the developing process but it may do so in discarding (of chemicals) process. The thing is I don't know if developing machine has separate drain for blix and developer or just one so it would be impossible to collect blix separately.
If it is possible of course I would ask them to do so.
rickbb
Well-known member
It may be a small shop and they just drain into one bucket to simplify their disposal. (And complicate yours.)
I've not seen an automated processer that did not have separate drains for each tank. Smaller systems are known as closed systems, just a tank of each chemical with no automated way to replenish the levels.
Larger systems with automated replenishment will have the overflow stack pipe in the fix tank separate from the others to accommodate an inline silver recovery unit. They could have placed all their overflow stacks in the one bucket again just to simplify their disposal.
You should still be able to recover, it will just have less concentration in the liquid volume as the added developer will dilute the fix/silver ratio. If they can just give you the fix you'd be better off with less volume of liquid to work with.
If you have a good relationship with them you may want to look into putting a recovery unit inline with their fix overflow. You own and service the unit and collect and recover the silver. They get to stay in compliance with their discharge permit. (If they have one, which they should.)
I've not seen an automated processer that did not have separate drains for each tank. Smaller systems are known as closed systems, just a tank of each chemical with no automated way to replenish the levels.
Larger systems with automated replenishment will have the overflow stack pipe in the fix tank separate from the others to accommodate an inline silver recovery unit. They could have placed all their overflow stacks in the one bucket again just to simplify their disposal.
You should still be able to recover, it will just have less concentration in the liquid volume as the added developer will dilute the fix/silver ratio. If they can just give you the fix you'd be better off with less volume of liquid to work with.
If you have a good relationship with them you may want to look into putting a recovery unit inline with their fix overflow. You own and service the unit and collect and recover the silver. They get to stay in compliance with their discharge permit. (If they have one, which they should.)
Thank you, those were some very useful information. I'm in good relations with them so if it is technically possible they will separate the fixer. It is a small studio so it would not be profitable to put recovery unit there. They are very close to me so it is simpler to just pick up the chemicals. Thank you again for your help.
Well, there was an unfortunate development. They use all purpose chemical that go in machine for developing. It is called Fujifilm CP-49E. It contains NaOH, p-Phenylendiamine derivate, Benzolc acid derivate and Ammonium hydrogen sulfate...Did anyone work with this? I have used Cu wire test and nothing. I don't know is it because there is no silver or because it is whole new mechanism of reaction.
rickbb
Well-known member
According to Fuiji this is a process for their automated mini-labs to process color print paper. Here is a link to a PDF that explains it in detail.
It still uses a bleach/fix tank so there should be some way to separate and recover just that portion of the chemistry.
http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=4&ved=0CFoQFjAD&url=http%3A%2F%2Fwww.fujihunt.com%2Fapps%2Ffuji%2Ffujifilmnv.nsf%2Ffiles%2FFUJIFILM%2F%24file%2FAF3-0137E2%2520CP-49E%252012-2007.pdf&ei=BplzVPyNAcyuogTuk4HACw&usg=AFQjCNEeqbQS5hCJcCHDBXV2zEKquLMMgw&sig2=qrLBAcBLYBeJwt41BgGDvw
I hope that link works, looks complicated but I just googled Fujifilm CP-49E and this was one of many sites that came up.
It still uses a bleach/fix tank so there should be some way to separate and recover just that portion of the chemistry.
http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=4&ved=0CFoQFjAD&url=http%3A%2F%2Fwww.fujihunt.com%2Fapps%2Ffuji%2Ffujifilmnv.nsf%2Ffiles%2FFUJIFILM%2F%24file%2FAF3-0137E2%2520CP-49E%252012-2007.pdf&ei=BplzVPyNAcyuogTuk4HACw&usg=AFQjCNEeqbQS5hCJcCHDBXV2zEKquLMMgw&sig2=qrLBAcBLYBeJwt41BgGDvw
I hope that link works, looks complicated but I just googled Fujifilm CP-49E and this was one of many sites that came up.
Yea Manuel
finally, I got. I refjned my silver just okay till the final stage. Men this is cool. You guys out here on this forum: Harold and the likes....you guys rock.
Tnx Manuel, u r d bomb.
Ok if girls take your money from you after precious metal recovery, they aint gonna take mine (laughs).Ok, I just PM you. Please come over lets talk. Thanks.
finally, I got. I refjned my silver just okay till the final stage. Men this is cool. You guys out here on this forum: Harold and the likes....you guys rock.
Tnx Manuel, u r d bomb.
Ok if girls take your money from you after precious metal recovery, they aint gonna take mine (laughs).Ok, I just PM you. Please come over lets talk. Thanks.
Ubongrex, welcome to the forum. Please do not use text lingo. It is against our forum rules.Ubongrex said:
Dave
Juan Manuel Arcos Frank
Well-known member
Ubongrex:
INDEED!!!!!!.You are welcome.
Kindest Regards.
Manuel
INDEED!!!!!!.You are welcome.
Kindest Regards.
Manuel
Dumb question: what if the silver content of the fixer is less that 1.5 gram/L, ie the copper wire test takes, 10, or even 15 seconds. Is this fixer not worth refining? Please advise.Juan Manuel Arcos Frank said:
Regards,
Matt
