MELTING SILVER

[Michael Karr]

HAS ANYBODY MELT ANY SCRAP SILVER,AND IF SO WHAT TEMPERATURES DO YOU NEED TO MELT IT? MIKE

 

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[aussco999]

Hey Mike:

The melting point of pure silver is 962 C (1764 F), but if the silver is alloyed with a lesser metal, the melting point is reduced some. You could easily melt/smelt most base and precious metals, with the exception of PGMs, using a heat source of less than 2000 F.

Also, if you are going to all of trouble of melt/smelting silver, this would be a good time to do a purification process by using a flux to slag off some of the impurities. This process is done in a kiln or furnace and can produce 90%+ pure silver. If you are just using a high temperature torch, you might boil off some of the lesser metals, but mostly creating just a blob of metal.

There are some good books out there on melt/smelting of precious metals, and maybe a run to the nearest library would help. As a final thought, you could also do a fairly cheap chemical separation/purification process, if that is easier for you.

Good luck,

John

 

[bk]

Keep in mind that if you melt silver into ingots, you will probably need to have them assayed if you intend to sell them. An assay can be pretty spendy.

 

[thudson]

How would you go about doing a chemical separation/purification ? Is this an easy thing to do? I have a bunch of Canadian silver that is .800 pure that I would like to separate. Anybody have an easier way than the chemical method ? Thanks Tyler

 

[Peg Leg]

thudson, It would appear that you have some Canadian coins you want to smelt.
I suggest that you leave them alone and sell them as coins.
But if you want to play around I suggest that you purchase some NITRIC ACID AND DESOLVE YOUR SILVER WITH THIS ACID.
When all the metal is dissolved you now talke some TABLE SALT and start to sprinkle the salt into the acid. You will see the salt start to turn gray as it falls to the bottom of your container. Keep adding the salt until nothing but salt is falling down. Now pour off the liquid into another container. On the bottom you will see a gray material. This is silver chloride.
Now add CORN SYRUP the same type syrup that you put on your pancakes. Slowly pour this CORN SYRUP into the container withe the gray materail and stire. The gray material will start to turn black. This is now PURE SILVER. Melt and pour. This silver will be no less that >99% pure silver.
You can expect to pay about $35.00 for a gallon of Nitric acid unless you have a chemical suppler close by.
Wear rubber gloves and goggles and DO NOT breath the fumes-do not DO THIS IN YOUR HOUSE.
This is very corrosive and will distroy whatever it touches including your SKIN.
Srart with a few coins at first and keep adding the coins as they dissolve. DO NOT POUR to much acid because it will boil over-just pour enough acid to cover the coins and NO MORE.
REMEMBER THIS THE ACID WILL TURN GREEN AND DARKEN BECAUSE OF THE COPPER THAT IS ALSO BEING DESOLVED ALONG WITH THE SILVER.
This is the easies and cheapest way to recover silver

 

[jocap]

If you do a google search for melting kilns and crucibles for the jewelry industry you will find exactly what you are looking for.

Many in that field often melt down old silverware and reuse fragments of gold and silver from repairing and filing of jewelry ( fine filed particles that fall onto their tray ). From what I remember the kilns and crucibles can be had fairly cheap.

HH

 

[Peg Leg]

Kilns are not cheap but curcibles can be purchased on ebay very cheap-some of them anyway.
I you are planning to do a lot of melting then you can build you own melting furnace cheaper than you can buy one.
Peg leg

 

[goldsilverpro]

There was a lot of erroneous info given in the above posts. If you want the correct info, try the following source. The info is scattered, but most every question you had is answered somewhere. If not, someone could answer any question you might pose. This website has been running slow during the morning and early afternoon. They are in the process of changing to a paid website hoster and things should improve shortly.

http://goldrefining.110mb.com/phpBB2/index.php

 

[EDDE]

point out the erroneous info please
just curious so many"experts"so little time

 

[goldsilverpro]

A couple of errors

The most common metal that silver is alloyed with is copper. You can't separate the copper by "slagging it off" using common fluxes. In theory, you might use sodium nitrate to convert the copper to copper oxide and slag it out. In practice, however, this would quickly eat holes in the crucible.

Using corn syrup (Karo) alone won't convert silver chloride to silver metal. You also need sodium hydroxide (lye; caustic soda). The sodium hydroxide converts the silver chloride to silver oxide. The syrup converts the silver oxide to silver metal. For a troy ounce (31.1 grams) of silver chloride, you need about 15 grams of sodium hydroxide, 10 mL (cc's) of light Karo syrup, 100 mL of water, and a lot of stirring. The silver chloride must first be well rinsed to remove any traces of nitric acid and dissolved copper. In practice, it is difficult to convert all of the silver chloride to metal, especially if the silver chloride has been allowed to dry.

 

[hollowpointred]

why not just sell your scrap silver to midwest refineries and leave all of this high temperature, corrosive dangerous chemical stuff to the experts?

 

[goldsilverpro]

I am a expert. Refining precious metals was my full time profession for 40 years.

Some people just like to do it. Probably, the people that had chemistry kits when they were kids. It's fun. No different than prospecting or hunting for treasure. It's just a different way to hunt for gold and other precious metals. Also, some don't like being cheated by refiners.

 

[Urban Prospector]

"Refining precious metals was my full time profession for 40 years"
"Also, some don't like being cheated by refiners."


No offence meant but these two statements conflict a bit, or do they?

 

[goldsilverpro]

Not at all. I didn't say that I stole. I've owned 2 refineries but, the rest of the time, I worked for big and small refineries. They almost all stole. Not all, but most. I saw what they did and how they did it. Everybody I've ever known, that commonly sends material to refiners, has horror stories. Refiners take in material on a "recovery basis", process it, and then pay you. They count your money for you. When you give them a pile of gold scrap, no one really knows exactly how much gold is in the pile. I call this the "gray area." Only the person who refines the material has a zero gray area. Karat gold scrap has a low gray area, about 1 to 5%. Mixed computer scrap's gray area might be 50%. The refiner knows, instinctively, the gray areas. He only steals within the gray area, in order to get repeat business. Because a refiner knows that he can fudge a "little bit", to take care of his needs!, there seems to be a lot of low charges, in order to get you in.

These low charges make it difficult to be honest and still compete. Let's say X Co. is charging 10% to do a certain type of circuit boards. The gray area on this batch is 40% and it actually COSTS them 20% to process your stuff. To cover the nut and the profit, they can lower the actual yield by 30% and charge you 10% on what's left over. And you'll most likely never bat an eye and come back for more.

When I had the refineries, I never took stuff in on a "refining basis". I always evaluated the material and bought it outright. That way, negotiations took place, everybody was happy, and no dishonesty or money loss was possible if I first got all my ducks in a row.

 

[fiatboy]

Thanks for the insight, goldsilverpro. Anything else one ought to be aware of regarding the business of refining metals?

 

[jewelerdave]

Some of the info above is not correct.

As someone who does melt a lot of silver and gold and uses it in our jewelry designs we are always looking for cheap gold and silver to use. It expands profit margins.

Most scrap silver is of a known quantity. either 80% 90% .925 or fine.

Jewelry grade has to be .925 or slightly better to be legal sterling according to the 1982 stamping act.

It is very easy to alloy scrap coin, old sterling, and damaged collectible .999 rounds/bars ect into .925 for use in casting.

however, Solder screws up castings and causes bubbles and weaknesses in the metal.

refining gold is easy, when you have the right stuff.

As for silver, All of our scraps, shavings, stuff with solder on it, filings and other such unknown alloy scrap just gets put aside and sent into a larger refiner for them to deal with. Take the small hit on the refining fees and take the cash to buy and find more undervalued metals and start over.

One can do it them selves and nitric acid is the way to go, dissolve it, add NON IODIZED SALT! the iodine will make it a pain. You get Silver chloride, This can be melted with lots of flux to get .999 fine silver back.
Its generally more of a pain than its worth. Unless its for a personal stash or your going to use it. The only time I ever pull silver back out of solution is to recover silver from etching jewelry, The nitric dissolves a little silver off and after about a year the solution is no good and stops dissolving, at that point we add the salt, strain, dry, flux and melt and get back maybe a half ounce, witch in turn gets remelted into sterling and used. When we have a bag of silver scraps that is a good number of pounds we send it and let a larger refiner deal with it.

Below is a pic of some of the silver we recovered, along with some gold and palladium we use.

 

[FISHEYE]

99% of refinerys in the USA will rip you off.there is only 1 that i will deal with.what they do is grind up everything you send them into a fine powder.they then take a small percentage of the powder and do a assay on it and pay me accordingly for the total weight.i can either get a check or pure gold or silver bars.stamped with the weight and purity.

 

[EDDE]

99% of refinerys in the USA will rip you off.there is only 1 that i will deal with.

who ?

 

[Auseeker]

Can the procedure outlined above be used to refine sterling silver? And if so, how much sterlign do you need to get 1oz pure silver?

 

[goldsilverpro]

Sterling is 92.5% silver and 7.5% copper, in theory. In practice, it will vary a bit, almost always on the low side.

Here's an easier way. It avoids the silver chloride, which is difficult to work with. I assume you're doing sterling. It also works for the big silver contact points but it will take a bit more nitric.

(1) Wear rubber gloves and a full plastic face shield. Dissolve the sterling in 50/50 nitric acid. Do this outside or under a fume hood. Theoretically, one tr.oz (31.1 gms) of sterling will require about 44.6 mL of concentrated nitric acid plus an equal amount of distilled water. In practice, use from 5% to 10% extra of each. Copious amounts of toxic red-brown nitric oxide fumes will be emitted. I would put the metal in a bucket and cover it with the required amount of water. Put the bucket in a plastic tray, in case it foams over. Measure out the required amount of nitric acid. Add about 1/4 of the nitric to the bucket. If everything isn't too cold, it should start working (fizzing and producing brown fumes) almost immediately. On occasion, stir it gently with a plastic rod (piece of a plastic coat hanger). When the reaction dies down, add more nitric. Repeat until all the acid is in. The metal should all be dissolved. If cold out, it could slow things down.

(2) Filter the solution to get all the dirt out. Use 3 or 4 coffee filters and a plastic funnel. Rinse a couple of times with distilled water.

(3) Put the solution and rinses in a plastic bucket. Stand up pieces of clean copper in the solution. They should be long enough to stand out of the solution, so they can be easily removed. Don't use copper wire. Copper buss bar is best (scrap yard). Copper tubing can be used but, when you cut it, use a tubing cutter. You don't want the ends crimped. Whatever you use, it should be clean . No solder, no plating, no connectors. Just clean pink copper.

The silver will automatically plate out in non-adherent lumps. It may take a day or two for it all to come out. Stir occasionally. Test for completion by adding a single drop of salt water or muriatic acid to the solution. If no white cloud appears, you are finished. Remove the copper and scrape any adhering silver into the bucket. If you used copper tubing, there will also be silver on the inside.

(4) Add about an equal amount of distilled water. Stir and then let the silver settle. Carefully and slowly pour off the solution without disturbing the settled silver. Put the wet silver sludge in a filter. When it stops dripping, rinse with distilled water. Repeat until all the blue color is gone. The better the rinse, the purer the silver.

(5) Dry the silver and melt, using only a little borax. A crucible furnace is best. If you use a gas/oxygen torch and a jeweler's melting dish with a handle, don't overheat. Do this outside - if it gets too hot, some silver will evaporate and, you don't want to breathe these fumes. Just get it molten and pour it in a hot mold.

The silver will be about 99% pure, max. For higher 99.99% purity, you will need to put the silver through an electrolytic silver cell.