I am hoping someone can help me as I think I may have screwed up bout 100 ounces of sterling silver. So when I dissolved the items in the sulfuric acid I wound up with nothing but a gray sludge I even added a lot more acid and still the same. Can someone please help me in the right direction?
Trouble processing silver with sulfuric acid
- Thread starter Silverdan
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Why did you use sulfuric acid and not nitric acid?
Silverdan said:
Can you provide some pictures?
I'm not sure what you did, but maybe you should do it this way with sulfuric acid:
1. Completely dissolved with concentrated sulfuric acid.
2. Heat until all mixture is white fuming and thickens.
3. Allow to cool and mix the thick mud with 5 parts water, heat for a few hours.
4. Filter to extract the solution and then your silver will be in the form of Ag2SO4 solution.
You can separate silver from solution in several ways such as copper cement or AgCl precipitation
You must ensure absolute safety because hot thick sulfuric acid is dangerous you probably understand that too.
nickton
Well-known member
Supposedly Hoke mentions it somewhere, and here's a link to one of Sreetips' videos on using sulfuric for silver refining: https://youtu.be/pdzSmGYbzqk.
Martijn
Well-known member
Suggesting a new member should try experimenting with a large volume of hot (concentrated :shock: ) sulphuric is not something I would do.
Maybe recovering the silver the way Hokes describes? Other members may have more suggestions on how to proceed.
Study and read a bit more first. The silver will stay there waiting for you with a plan.
The fact that you did not notice or checked your acid tells me you have some more to learn first. (and not from You-Tube)
When you try something, use small amounts in test tubes. You won't mess up a lot and keep it safe to get familiar with the reactions.
How strong is the sulphuric acid you used? Silver sulphate is not very soluble in water, like half a gram in 100ml, I don't know how much concentrated sulphuric can hold. It may have all reacted and then dropped out because of oversaturation. not sure.
https://en.wikipedia.org/wiki/Silver_sulfate
I guess the sludge in the bottom is silver sulphate with some base metal sulphates.
Be very carefull with sulphuric acid.
Martijn.
Maybe recovering the silver the way Hokes describes? Other members may have more suggestions on how to proceed.
Study and read a bit more first. The silver will stay there waiting for you with a plan.
The fact that you did not notice or checked your acid tells me you have some more to learn first. (and not from You-Tube)
When you try something, use small amounts in test tubes. You won't mess up a lot and keep it safe to get familiar with the reactions.
How strong is the sulphuric acid you used? Silver sulphate is not very soluble in water, like half a gram in 100ml, I don't know how much concentrated sulphuric can hold. It may have all reacted and then dropped out because of oversaturation. not sure.
https://en.wikipedia.org/wiki/Silver_sulfate
I guess the sludge in the bottom is silver sulphate with some base metal sulphates.
Be very carefull with sulphuric acid.
Martijn.
I have processed it with 98% sulfuric, it is cemented I think into a dark gray semi hardened state. I have 2 different batches. This one in the picture I stopped because I thought when it was processed the acid was supposed to be clear? And as far as experimenting with hot sulfuric acid I’ve already had my trial and error experiences.
What do you suggest filtering with?
What is the process after filtering?
What do you suggest filtering with?
What is the process after filtering?
Attachments
Concentrated sulfuric acid will dissolve silver, however, the amount of silver dissolved is less than desirable. It is also possible that the sulfuric acid while dissolving the silver will make a silver mud. In order to clean up the issue, I would dilute the solution with the silver mud using some distilled water, and filter the mud from the liquid. Save the liquid and rinse the mud several times using distilled water all while accumulating the liquid. I would then add HCl to the accumulated liquid to make silver chloride and convert the silver chloride using the many options available. I would then mix in some sodium carbonate in with the silver mud and melt the mixture and pour off the molten silver and form a bar. Then I would dissolve the silver bar using nitric acid and distilled water.
Martijn
Well-known member
Silverdan, how did things go? I sure hope you diluted the acid by pouring it in cold water, not pouring water in the concentrated acid....
I faced a similar issue today. i refine silver clad on copper scrap here using hot concentrated sulphuric acid that leaves the copper almost as it was and just dissolves the silver. i was taught this method by someone who didnt warn me about silver sulphate then. the sludge at the bottom is indeed silver sulphate and as everyone here knows it doesnt dissolve in water so much. i precipitated the silver from the solution using copper while leaving the white sludge in the solution only. Then after washing and drying the silver cement i went on to melt it while setting the furnace temp to 1100 c.after sometime i noticed the silver(or silver sulphate) was vigorously boiling and very strong sulphuric fumes coming from the furnace.i immediately cooled the crucible down and started googling as i was sure i had thoroughly washed the silver powder and no sulphuric acid should be remaining.now that i know that it was silver sulphate boiling at above 1085 c ,im worried about how much of my silver went up in smoke. the lot that i was refining had about 15 kg of silver, will now dissolve this silver sulphate molten mass in nitric acid and see how much i have lost.
any tips before i go on and try recovering using nitric acid ?
any tips before i go on and try recovering using nitric acid ?
If ever you melt any silver from sulfate processing, it is most wise to use borax cover and several pieces of rebar:
The iron turns silver sulfate to silver metal and iron sulfide slag is the final product.
The iron turns silver sulfate to silver metal and iron sulfide slag is the final product.
The white sludge is anhydrous sulfate salts caused by the sulfation of sterling silver coins.
Dissolve it in water and heat it up to 90-100 degrees for a few hours.
All the silver sulfate will dissolve into the water into a silver sulfate solution, then you can proceed to filter to separate the insoluble precipitate.
Silver sulfate solution you can cement it with clean copper or precipitate silver in the form of silver chloride and do the next job so that it becomes cement silver easily with Lye + sugar or Zinc + HCl.
Hopefully that little bit of advice can be of help, as I'm working on restoring a huge amount of silver with hot concentrated sulfuric acid.
Wish success.
Dissolve it in water and heat it up to 90-100 degrees for a few hours.
All the silver sulfate will dissolve into the water into a silver sulfate solution, then you can proceed to filter to separate the insoluble precipitate.
Silver sulfate solution you can cement it with clean copper or precipitate silver in the form of silver chloride and do the next job so that it becomes cement silver easily with Lye + sugar or Zinc + HCl.
Hopefully that little bit of advice can be of help, as I'm working on restoring a huge amount of silver with hot concentrated sulfuric acid.
Wish success.
kadriver
Well-known member
I used sulfuric to dissolve silver. But the silver needs to be rolled very thin. I boiled the thin silver in 93% sulfuric acid until it dissolved completely. Then I used fiberglass filters (pricey) to filter the solution clear of solids. Then I added hydrochloric acid to the filtered solution, slowly because it spattered hot acid. Once all the silver chloride dropped I added water (yes, water to acid) very slowly until it turned a blue color. Rinsed the silver chloride real good with hot water then converted to high purity silver with lye and sugar. Didn’t use one drop of nitric acid. Here is a video that I made of the entire process: https://youtu.be/BocqoUyw1CISilverdan said:
https://www.youtube.com/watch?v=IeLczpPCqV8
This guy just added NaOH to silver sulphate and says that it converts to silver oxide which can then be processed with sugar to get pure silver.
I just never got the confidence to put silver obtained from sugar lye method in my melting furnace because during my early days some local 'refiner' who i had hired to help, went and ahead and blew away almost 2kgs of silver by trying to melt silver chloride .That loss i will never forget.
So we have been using pure copper strips to drop silver and produce silver powder.
But i guess there's no easy way to process silver sulphate but to use sugar/lye method.
I tried dissolving silver sulphate in water but this stuff is really tough to dissolve.
This guy just added NaOH to silver sulphate and says that it converts to silver oxide which can then be processed with sugar to get pure silver.
I just never got the confidence to put silver obtained from sugar lye method in my melting furnace because during my early days some local 'refiner' who i had hired to help, went and ahead and blew away almost 2kgs of silver by trying to melt silver chloride .That loss i will never forget.
So we have been using pure copper strips to drop silver and produce silver powder.
But i guess there's no easy way to process silver sulphate but to use sugar/lye method.
I tried dissolving silver sulphate in water but this stuff is really tough to dissolve.
David R
New member
- Joined
- May 31, 2023
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I'm not sure on how much acid you use but make sure you add more and boil it safely until all the silver is dissolved you will have a black bluish straight liquid with some other solids floating around but it usually takes 8 to 10 to 12 hours if not longer depending on the thickness of silver then after that let it cool down a little bit and then add hydrochloric acid AKA muriatic acid slowly in small doses it would immediately start foaming up and boiling to thermal reaction keep adding that and you're going to see a gray powder form on the bottom you're going to want to add quite a bit cuz you 100 oz is quite a bit of silver once you feel like you're not getting any more of that gray cement powder for me on the bottom you want to add some hot water and you want to start rinsing it you can rinse it in the same thing whatever you boiled it in and all that but you're going to be rinsing out it's going to be a blue liquid in that blue is the copper rinse it two dozen times with hot water and you can just pour it out the gray cement at the bottom should stay at the bottom it's heavier than water you want to keep rinsing it until you see no more blue in the water and then we see no more blue rinse it a few more times next leave a little bit of water in there at least enough to cover all that silver paste with the least an inch of water or so next you add lye, drain cleaner granules from Walmart that's 100% lye will work you would want a couple bottles it's going to turn the water and stuff black you want it to be jet black No Gray at all and then add sugar slowly there's going to be a reaction again Heat with 100 oz I'm going to assume you're going to probably want to add a cup or two if not more and then after that you just rinse that gray paste at the bottom another dozen or two times until you get the PH down the neutral and that great paste is your silver once you melt it should be pretty pure and remember safety boiling sulfuric acid will instantly charge your skin the fumes it gives off all those processes are not good also too when you add all the different chemicals you want to stir a lot
Welcome to us.
But please use punctuation and space dividers to break up your text, it is practically unreadable.
The concentrated sulfuric acid must be boiling hot when you use it to dissolve sterling Silver. That is how my instructor taught me, it has never failed me.
Martijn
Well-known member
Even though our famous and highly respected you-tuber sreetips advised it, we try to avoid advising people to use boiling hot concentrated H2SO4, it is kind of unforgiving.
If you still want to do so, please write a disclaimer and a list of precautions with it.
