Refining silver from smithing

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.

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?

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 (precipite) 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 (wich I catch from my airconditioner). Put the filter with the white stuff in a crucible in a burnout oven if you have, heat to 800 Celsius, 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 muriatic acid [linked by editor to product info at 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.

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.

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?

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 1.5oz 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 electrolysis