Refining silver from smithing
A discussion started in 2004 but continuing through 20182004
Q. I do lost wax casting and smithing. I refine gold with nitric acid at home, by mixing scrap gold of different karat with copper and then dissolving it in slightly hot nitric acid. That works very well for me. I have never come over a description as how to refine silver scrap, of which I get different amounts now and again. Mixed with solder, (chain links) or too much copper (coin silver) and so I ask if you can tell me how to refine scrap silver in my own workshop to get it (close to) pure again.Alexander Baldal
gold and silver smith - Sint Maarten, Dutch West Indies, Netherlands Antilles
A. I used to dissolve out my silver scraps in Nitric acid (at around 30% strength) This gave me a solution of Silver Nitrate (which is poison and will also burn or mark you or your sink or clothes - it will also burn out a wart or corn with several applications! It can also be used to purify water (but I do not know what is a safe way to do this.) I assumed that any lead or copper or zinc did not react with nitric and just fell to the bottom as "dirt". I poured this solution into a fresh glass (leaving the "dirt" behind. Then I mixed in a hot fairly strong salt solution and the silver nitrate precipitated out a white substance which you could filter off with a paper towel in a funnel. This white precipitate can be heated with your torch in a crucible and I got what I believed to be pure silver. I used to use it for casting as I suspected it was not as pure as I would have wished. I gave the remaining liquid a second dose of hot saline in case it still contained any silver. My father in law, a chemist (in Aruba!) gave me this procedure.Don O'Keefe
Q. I have found many different sites telling me how to refine silver with nitric acid. I was wondering if there is any other method I could use at home to refine it?Sean Peter Cake
hobbyist - Kutztown, Pennsylvania, USA
A. Not to mess with expensive nitric acid from the pharmacy I found the cheaper way to refine silver. I put 50 gram of Sodium Nitrate from a garden supply shop, (is a common fertilizer) in half liter Sulphuric acid from a car supply shop (is common lead battery acid) and in it unclean silver, in as small parts as possible, milled flat and cut, and/or filings, in a glass coffee pot that can take a gas flame and boil it for one or two hours, (no need for a lid as the water in the weak acid evaporates and makes it stronger) or until all is dissolved, pour the liquid through a common coffee filter. What undissolved metal stays in the filter goes in the next batch. Then I add very fine common kitchen salt, dissolved in a little hot water or just like that; dry. The white yoghurt like substance (precipitate) comes down in the liquid, until more salt does stay salt. Then pour the liquid through a new coffee filter and rinse with water until clean, to check add a little ammoniac (Janitor strength from the hardware store). If the rinse water turns blue, rinse more. Good to rinse last with distilled water (which I catch from my air conditioner). Put the filter with the white stuff in a crucible in a burnout oven if you have, heat to 800 °C, then remove from oven and put the torch, (Propane Oxygen will do) to get 100% pure silver. If you have no oven, let the filter dry , dip in alcohol and heat with torch. Same result. The same procedure for low karat gold, what stays in the filter after 2 hours cooking put in
[affiliate link to product info on Amazon]
with Sodium Nitrate, the gold will dissolve in room temperature, slowly, over night. Filter the liquid, what stays in the filter, rinse well and pour off what is light, any bits and pieces are good for a next time.
Dissolve some Urea ( also from the garden supply shop) in hot water and pour it slowly in the acid. It will foam and get hot, put your container in a big glass bowl in case it runs over. After the urea solution has gone in sprinkle Metabisulfite (is a salt butchers use to keep meat from turning brown, also used in wine making, water purifying, a common house hold item in a pharmacy) and see it foam and smell it stink, do work upwind. When brown-red particles go down, that is the pure gold.
Instead of Metabisulfite you can use common copper, old water tube or electric wire. As long as the copper dissolves the gold is pushed out of the acid. When the copper does not turn black any more the gold is out of the acid. To test for gold in the acid, make test water. That is pure tin, (lead free water tube solder from the plumber department hardware store) dissolved in a little muriatic acid. Put a drop on a paper towel, then add a drop of the liquid to test for gold. If it gets black gold is in, if it does not turn black all the gold is precipitated.
Good luck and have baking soda [affiliate link to product info on Amazon] at hand to neutralise any acid spill. Put a bowl with baking soda in water to dip hands and rinse acid tools.
Filter, wash and rinse like the white stuff, the pure gold does not turn black after cooling in air.
Atelier Amador - Sint Maarten Netherlands Antilles
Ed. note: Thank you, Alexander. But readers, please remember that the internet is a giant one-room schoolhouse and that some of the instructions you "overhear" on the internet may be totally inappropriate for a home environment or for application except by trained professionals.
A. Just a warning, anyone who is using these methods: dissolving the silver in nitric acid works well, be sure not to breath in the toxic fumes. Also, the white powder formed after adding salt to the silver solution is silver chloride. Heating this powder with a torch will give you pure silver, but it also produces pure chlorine gas, so be very careful if you are using this procedure. A safer way to recover the silver is to mix the silver chloride with sodium carbonate (can be bought at pool supply stores), heat to around 1200 degrees C, then pour out the mixture. Products are table salt and pure silver, which will separate in liquid phase due to extreme density differences. If you know anything about chemistry, you can work out the reactions and mass ratios. Cheers, happy refining.Dave Bahn
- Penn State, Pennsylvania, USA
July 22, 2008
Q. I am purchasing a high temperature smelting furnace for melting down items that are "pure" as possible and other materials that have mixtures of gold and silver, silver and copper or a mixture of all three. How am I to separate these precious metals from one another and how do I make the final outcome the finest grade possible?Duke McNichol
metal detector enthusiast - Clayton, North Carolina U.S.A.
A. Assuming your scrap is either .925 or sterling there isn't much need to really refine it and it's impossible to refine to purity without a electrolysis. The purity of anything marked 925 or Sterling is already 92.5% pure silver. One method of reducing some of the impurities would be to dissolve the silver in a 30-35% nitric acid solution. This solution will give off poisonous and acrid fumes so use a hood, vent or do this outdoors. for an ounce of silver scrap (again assuming it's .925) you might want to use about 1.5 oz of diluted nitric. when no more silver is present, filter the solution and then you can recover the silver by adding muriatic (HCl) or regular non iodized table salt. Both will precipitate the silver as silver chloride which will have to be reduced to metallic silver by either a calcining process or reducing with zinc. An easier method of recovering silver from silver nitrate is to simply add a piece of clean copper. This will cement your silver as cement silver which will run about 94% pure. Again, to refine the silver to 999 purity, it will require electrolysisGreg Alford
- Kansas City, Kansas, USA
September 28, 2008
Q. Refining Silver From a Mine? I've recently come home from a "Silver Hunting" trip from some past producers. I've found some nice samples of wire and plate silver which I want to keep. I've also found some ore that contains a high content of Cobalt and Arsenic not much visible Silver so I cannot visually remove the Silver.
How could I remove the Silver (in small batches 1-2 lbs total ore weight) safely and cost effectively.I want to have a local Jeweler make some silver Crosses for my Wife and Daughters for Christmas.
rock hound and amateur prospector - Queensville, Ontario, Canada
A. The simplest way to extract gold from mixed ore after powdered to over 100 microns?
right on the mining site, with less complicated resources possible, fast easy and efficient, please any one know how?
I always pray for the peace of Jerusalem so you may prosper (that is what the Bible states) I follow!
- Newton Falls, Ohio
July 8, 2010
A. An easy (all disclaimers included) way to separate fine gold from jewelry is an old method called "Parting"
I put this site up a few years ago. Some of it is incorrect, like the names of things. But parting is an old method and it works.
I wouldn't recommend it to the casual putterer, but if you're not scared of dying, it's fun!
the department of redundancy dept. - Powell, Tennessee, USA
Q. This was the most informative site I've looked at ever.
I have been looking for and finding plenty of gold nuggets since becoming disabled at 55. The last 2 years I've been working a good gold vein which recently ended after I broke through into a cave. No Gold but 2 huge veins which I hope to be silver, white crumbly rock which turns to mud when wet, I sent it in to be assayed and should have the report tomorrow. was wondering if I just could have used one of the methods described on this site. Bob
- Sherman, Texas
November 5, 2010
Q. Hi, I was actually trying to extract silver from a silver nitrate by using salt. the result was actually fine at first; unfortunately, one of my friends said it has a better outcome if I add a baking powder. there's where my problems started. It seems that baking powder is neutralizing the reaction of the salt from silver nitrate. and now I'm having trouble how to extract the silver when it has a baking powder. can anybody help me how to fix this?Dexter Acope
buyer - Monkayo, Compostela valley, Philippines
December 5, 2011 -- this entry appended to this thread by editor in lieu of spawning a duplicative thread
Q. I have some silver which the jeweler says he can't do anything with because its has too much impurities how can I clean the impurities out its a big chunkDamien Roberts
March 22, 2012 -- this entry appended to this thread by editor in lieu of spawning a duplicative thread
Q. I while trying to melt few silver beads in a crucible I noticed that iron rust are scattered inside the crucible and these iron rust got mixed with the silver beads when molten. How can I get the iron rust removed from the silver beads?khalid Aamoudi
- jeddah,Saudi Arabia
A. When firing, add your material to your crucible and cover completely with a cap of soda ash. And don't be conservative about it. Place a bowl cap/cover on the crucible and fire it until all the soda ash is molten. Then remove the bowl cap/cover and let it fire for an additional five minutes. This should solve your problem of metal contamination. If I'm not mistaken the soda ash will allow the other contaminants to burn out, NOT the silver.
I just did it. I have spent the last two days mining.
Today was test firing. Hoorah!! .97 troy oz.!
Blood red on the tester!
- Gilbert, Arizona USA
August 6, 2012
Q. Dear Sir.
First of all, I want to apologize for my bad and poor English, so I will try to do my best to speak to and write to you, Sir.
I need your precious help.
My father is a goldsmith, and in the past few years (25 years) he works a lot with silver and gold, and now he stops working, and he wants to refine 20 kg of 0.900 silver that he has into pure silver, and he wants to sell it.
I looked around a lot in google, and I found many articles but I can't find anything that explains to me step by step (like a tutorial) how to build an electrolytic cell to refine silver.
So, I need to ask you this: do you know how to build an electrolytic cell? Do you know Moebius cell or Dietzel cell? Reverse electroplating? What seems to be the best process to refine the 0.900 silver to pure silver. Can you help me please?
I will wait for your reply soon.
Many thanks for your help.
- Porto, Portugal
October 4, 2012
Q. I have a 30 lb bar of 60% lead and 40% silver that I would like to separate, but I do not know how to best separate it. Help!john r. uronis
Recovering silver from silver plating on ironMarch 13, 2015
We have a metal with base of Iron with silver and copper coating at certain points. The metal also has small traces of Nickel, Chromium and Moly blended in with Iron itself.
We are looking to separate/recover the silver from the metal.
Would appreciate a response to the issue.
Steels & Scrap - Mumbai India
March 22, 2015
A. Dear sir,
Main thing: if your material is a metallic or in powder or ore form; and how much quantity of Silver in percent (test in lab) is important for refining process.
cac admixture - mumbai,india
Recover silver from a bucket of mine sludgeJuly 26, 2016
I am not a student nor a chemist but a dabbler of lapidary and silver-smithing -- therefore I am used to playing with metals, casting jewelry but no chemist! Background: I bought a used rock saw - which contained 5 gallon pail of silver sludge from the previous owner who cut silver ore from his mine. Now I am working on reducing the sliver sludge down to silver.
Process so far: I am removing the mineral oil from the sludge by burning the sludge (after filtering the oil off as much as possible). I have now taken the ash and heated it in the kiln to 1940 degrees with borax as a fluxing agent. Once complete I have dropped the liquid metals from the crucible into a bucket of water. I now have long thin chunks of silver and a lot of flux holding onto the rock dust ore as well as other non-metal impurities.
As for my assay results - 2.5 oz metal (mostly silver) from 1 lb of sludge.
So now my questions! I am setting up to dissolve the metal in nitric acid and try to reclaim my silver as pure as possible.
1. the saw had a lot of rust inside and is mixed throughout the sludge. I have done a lot of research on reclaiming process but nothing I can find that talks about what will happen if my solution is heavy in iron. Can anyone tell me if the iron will also try to precipitate out? Is there an extra step I need to do before/after I try to drop the silver out of the nitric acid solution?
2. since this is mine-run ore that was cut in the saw - I expect other metals to be present in the solution (lead, copper, zinc, gallium?). How can I
safely extract these metals (as a byproduct or separation) during this process? Are there certain metals that should be taken out of solution first, second, etc?
Thanks for your help!
- Almont, Michigan, USA
Ed. note: We doubt that an untrained non-chemist can "safely extract" silver using nitric acid and other chemistry from a bucket of who knows what, but please be sure to study "fulminates" before you attempt any of this.
February 26, 2018
Q. I took some 3 inch rings and had them shot with a gun. It said they were almost 50/50 silver to copper.
I took the rings and melted them down and poured them in a pan of water and made them smaller pieces. I drained the water off and added my acid mixture and let it set for a little while. I proceeded to start recovering the silver. I weighed the rings before I started; they weighted 29.6 grams. When I was done with the acid I recovered the silver and other materials I ended up with 4.5 grams. What can I do to get the silver to drop?Lloyd Simoneaux
- Saucier, Mississippi