Silver refining problem: Removing copper from silver nitrate
A discussion started in 2000 but continuing through 2018(2000)
Q. In the process of refining pure silver, we end up having a lot of copper in the electrolyte (silver nitrate). The efficiency of the process diminishes as the copper concentration increases in the bath. I am wondering if there is a process where I can regenerate the electrolyte (AgNo3) by removing the excess copper from the solution.
I would greatly appreciate anybody's help.
Thank You.Ajit Menon
- Alden, New York, USA
A. Dear Ajit,
Selective removal of copper from AgNO3 can be performed by ion-exchange, provided the pH is not below 1.5. The key will be to minimize silver loss by extensive wash of the resin or by use of a continuous counter current ion-exchange system (ISEP).Ruud Gerritsen
Recomet B.V. - Simpelveld, Netherlands
September 16, 2012
Q. I noted the suggestion of Mr. Gerritsen to use a counter current ion-exchange system (ISEP). I have refined 80/20 Ag/Cu for a while in a AgNO3/HNO3 bath, but I think I have got to the point of copper contamination of the electrolyte, like the original poster. Is there a way to electrically remove the copper and keep the AgNO3?
Tom, who just started this stuff and finds it fascinating.
- Tuckahoe, New York
A. Have you thought of precipitating the Ag with HCl and resmelting with Borax [linked by editor to product info at Amazon] and flour to obtain about 95% Ag which you can redissolve in HNO3 to get your electrolyte?Edmund nkrumah
- Accra, Ghana
Moebius cell technique leaving impurities in refined silver(2002)
Q. What could be the cause of having impurities in refined silver using the moebius cell technique, when crystals obtained have been thoroughly washed with deionised water?Edmund Nkrumah
- Accra, Ghana
Only achieving 50% silver recovery; need 90-95%May 8, 2009
Q. We are facing the problem of silver recovery from silver and copper mixture. We are refining the silver metal as silver chloride and copper as copper cathode, by electrolyzing process.
We get silver chloride from the electrolytic solution by addition of HCl. Rinse we filter the silver chloride from the solution, After the many water wash, we melt the silver chloride by addition of borax and carbon powder. But we are getting the silver recovery only 50%.
Please help me to get about 90 to 95 percent recovery of silver metal at least.
Please reply us as soon as possible.
hobbyist - Rajkot, Gujarat, India
November 8, 2014
A. If your silver nitrate solution gets saturated with copper, cement the silver nitrate out onto copper, you will get elemental silver, and one could get the copper nitrate out by cementing onto iron (after washing and separating from the cemented silver), you're left with iron nitrate and copper oxide, I believe, but the cemented silver is clean enough TO MELT and make new electrolyte again. DON'T put the cemented powder back into nitric. Nitric reacts explosively with metal powders, because of the large surface to act on!
Cementing onto copper:
I'm not an expert in refining, merely a student of this interesting science, but that's what I would do to get rid of silver electrolyte saturated with copper. Copper is close to silver on the reactivity series, =>
with only mercury and tungsten in between. Pt and Au will not be in a nitric solution, so pretty pure Ag is to be expected. Why bother making AgCl first and having to melt and waste borax?
Use this info (and everything else you find on internet, for that matter) AT YOUR OWN RISK!, it's purely for theoretical purposes, be educated and sure of what you do.
read MSDS! be safe!
Melting silver chloride will produce chlorine as well =>
- Zeeland, the Netherlands
January 30, 2015
A. To recover silver from silver nitrate solution I prepared a reagent which is directly added into silver nitrate solution. No need to precipitate as silver chloride. It works nicely and the purity of Silver is 9999.Daulat Bhosale
- Bangkok Thailand
February 13, 2015
Dead keen to know what your reagent is -- organic?
- Fairfield, Australia
February 15, 2015
A. Yes. The reagent is a mixture of three organic compounds. Watch the video on you tube. Recovery of silver from silver nitrate solution.Daulat Bhosale
- Bangkok Thailand
June 14, 2018
Q. Can anyone tell me the how should I calculate the ratio of copper powder (red) to separate the 99% silver from copper nitrate (solution of impure silver + 70% nitric acid)?dee kay
Dk Assay - mumbai,india
June 25, 2018
A. Theoretically, 1 gram of copper will cement (reduce, precipitate) 3.4 grams of silver from a silver nitrate solution. However, if there is any free nitric acid in the solution, copper will be dissolved by the nitric until the nitric is all consumed, before cementing any silver. It takes about 4.15 ml of 70% nitric (15.7 molar) to dissolve 1 gram of copper.
With copper powder, you must use an exact amount, which is difficult to predict, especially if any free nitric is present. Any undissolved excess of copper powder will co-mingle with, and contaminate the cemented silver powder.
The best copper to use is scrap, un-plated, clean, copper buss bar, with no solder on it, cut into pieces long enough to protrude up out of the solution, so they can be easily removed. Heavy, solid copper wire can be used, but, here again, the pieces should be long enough so they can easily be removed. Copper tubing can also be used, but, since the silver will also cement on the inside of the tubing, most people flatten it before use.
- Benton, Arkansas, USA
July 31, 2018
Use of copper for silver refining is costly; there are several processes you can use for silver precipitation.
CAC admixtures - Mumbai,india
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