# Smelting



## Startingout-Blair (Aug 28, 2012)

Does anyone know how to take old silver and/or gold jewelry, melt it down for pureness, and then mold into bars or small ingots?


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## zombieresponder (Aug 20, 2012)

Offhand, I don't know the melting point of gold or silver, but I would suggest using a stainless melting pot. If the metals alloyed with the gold or silver have a different melting point than the base metal, then keeping the temperature above or below the melting point of the silver/gold should allow you to skim either the desired metal or the impurities out of the pot.

That's the best way I can explain it, based on my experience with smelting lead.


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## Startingout-Blair (Aug 28, 2012)

zombieresponder said:


> Offhand, I don't know the melting point of gold or silver, but I would suggest using a stainless melting pot. If the metals alloyed with the gold or silver have a different melting point than the base metal, then keeping the temperature above or below the melting point of the silver/gold should allow you to skim either the desired metal or the impurities out of the pot.
> 
> That's the best way I can explain it, based on my experience with smelting lead.


Thanks! I read somewhere that they make crucibles? Some type of ceramic bowl for heating metals? Not sure


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## Marcus (May 13, 2012)

Startingout-Blair said:


> Does anyone know how to take old silver and/or gold jewelry, melt it down for pureness, and then mold into bars or small ingots?


First recognize that unless you're in the jewelry business in a major way, it's not practical to do it.

Temperatures required:
http://www.engineeringtoolbox.com/melting-temperature-metals-d_860.html

A crucible is used to melt gold or silver (1900+ or 1700+ degrees) to allow impurities to be removed.

http://science.howstuffworks.com/gold5.htm


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## Startingout-Blair (Aug 28, 2012)

It was my thought to have that skill after SHTF. If some people have jewelry and it is poor quality, I figured smelting it to get the purity would be a good idea. Not so sure now


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## Marcus (May 13, 2012)

It all depends on your chemistry skills since nitric acid is no joke to handle.
http://en.wikipedia.org/wiki/Nitric_acid
http://en.wikipedia.org/wiki/Aqua_regia


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## invision (Aug 14, 2012)

Startingout-Blair said:


> Thanks! I read somewhere that they make crucibles? Some type of ceramic bowl for heating metals? Not sure


Hey buddy, I started smelting Gold and Silver a few months ago...

First off, educate yourself as much as possible about how to do it on YouTube... I found a lot of good advice there as well as google searches before I even tried to do it..

Second here is a list of the tools you will need:
1) Get good quality Cucibles - yes there are ceramic ones, but graphites are better - get more than 1, get 3-4. The Flux you use (see borax below) can actually eat through ceramic ones (so I have read multiple places).
2) Get a gold/silver acid test kits with scratch pad - get a few of them in fact - they will test for 10K, 14K, and 18K gold, and silver. That way you can make little piles of the different K's to melt individually.
3) Get a scale - I have two, one is digital and one the three beam balance - get ready to pay a little dough here for the 3 beam.
4) get fire source - you will either need a propane torch or a furnace - I got the furnace instead of working with open flame (more safe IMO) - remember the melting point for silver is 1763.20 °F so that is HOT
5) you will need tongs to handle the Cucibles, grafite rods to stir while melting, and also a set of good welding gloves too. My Cucibles came with tongs. 
6) I have bought 1 ounce graphite ignot molds - I have 10 of them - so I can melt 10 ounces at once... I suggest getting at least 5.
7) you will also want to get Borax to cover your gold when you start to melt it... Many natural forms of gold contain impurities, so a flux is required to collect them and remove them from the gold. The more impurities which are present, the more the amount of flux that is required. Some small amount of flux should be used even when the material appears clean. Fluxes also help to hold together fine gold particles and keep the torch from blowing them away. Borax is a flux.
8) get a dye punch kit - .999, .925, .900, then 10K, 14K, 18k, 24K. and a letter set... that way once you melt your gold or silver you can properly stamp it to what grade it is...

I don't use the acid, as I don't trust myself with Nitric Acid... also why I haven't started scavaging the 15 PCs and servers laying around my house LOL


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## Startingout-Blair (Aug 28, 2012)

Thank you Invision! I appreciate your input. I will take a look at what you listed and see what I can obtain.


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## invision (Aug 14, 2012)

Startingout-Blair said:


> Thank you Invision! I appreciate your input. I will take a look at what you listed and see what I can obtain.


No problem... One word... eBay. I got all of my stuff except the welding gloves and dye punches on eBay... Better prices than anything I could find online


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## zombieresponder (Aug 20, 2012)

Marcus said:


> It all depends on your chemistry skills since nitric acid is no joke to handle.
> http://en.wikipedia.org/wiki/Nitric_acid
> http://en.wikipedia.org/wiki/Aqua_regia


I didn't see much there that really scared me. I used to work with acids that were calcium seekers and would weaken or dissolve your bones with just skin contact. :eyebulge:


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## invision (Aug 14, 2012)

zombieresponder said:


> I didn't see much there that really scared me. I used to work with acids that were calcium seekers and would weaken or dissolve your bones with just skin contact. :eyebulge:


Maybe, but I haven't played with a chemistry set since high school and college - wouldn't want to risk my life over cleaning out a small percentage of flex, when 1) gold can be acid tested for purirty and stamping purity levels are common :cheers:


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## goldy_pawn (Feb 12, 2014)

I have been melting my own gold/silver for years. The gentleman above by the name "invison" pretty much summed up the process. I have found a good website that offers many of the tools you need to get started with melting. They have several kits that would be perfect for a beginner who is just getting into smelting. The website is GoldRefiningSupplies.com I've ordered a few ingot molds from them and the quality is really good. Nice high density graphite, so you can get more pours out of them. Good luck with your melting!


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## LincTex (Apr 1, 2011)

invision said:


> ... also why I haven't started scavaging the 15 PCs and servers laying around my house LOL


You would likely be money ahead selling the used PC's and taking that cash and buying PM's


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## NaeKid (Oct 17, 2008)

Would it be a good idea to do some gold-panning and then smelting the gold into ingots? There are many streams near my home-town in BC that are "known" locally as good panning streams. One guy I know has filled a few medicine bottles with gold-dust. Last I talked to him, it had taken him 20 years of panning to get 12-ounces :rofl:


I think he does the panning more to get away from his wife - but - don't let her hear you say that - you'll get an earfull (which is why he heads out panning).


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## cantinawest (Nov 9, 2011)

*Solar Smelting...*

This is a little of the subject, but it does have to do with smelting...

It is quite impressive the power you can harness with this contraption.

I have also seen a parabolic cooker big enough to generate about 2500 F.


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## NaeKid (Oct 17, 2008)

cantinawest said:


> This is a little of the subject, but it does have to do with smelting...
> 
> It is quite impressive the power you can harness with this contraption.
> 
> I have also seen a parabolic cooker big enough to generate about 2500 F.


That video is cool - but it reminds me so much of a book and movie by Clive Cussler .... Sahara.


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## cantinawest (Nov 9, 2011)

I think I have seen the movie, but I don't remember at all what it was about.


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## NaeKid (Oct 17, 2008)

cantinawest said:


> I think I have seen the movie, but I don't remember at all what it was about.







:beercheer: :beercheer: :beercheer: :beercheer:


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## Viking (Mar 16, 2009)

zombieresponder said:


> I didn't see much there that really scared me. I used to work with acids that were calcium seekers and would weaken or dissolve your bones with just skin contact. :eyebulge:


I've delt with numerous acids over the years and the one that scared me the most was hydrofluoric acid, the calcium seeker. When I worked custodial/maintenance at the local school district they had a urinal/toilet cleaner named "Sixty Seconds" that had hydrofluoric acid in it and you didn't dare leave it on the surface of the porcelain longer than sixty seconds or it would cut right through the glass surface of the porcelain. Seems to me that I remember that it was taken off the market because it was so dangerous to handle, I remember reading that hydrofluoric acid would go through the skin and directly to the bones. About seven years ago while down in N. Nevada for gold detecting I saw a guy using pure hydrofluoric acid to remove quartz from large gold nuggets, I warned the guy but he didn't seem too concerned, but then he wasn't in the best of health as it was. Any smelting should be done where you don't breath fumes, gold and silver are often alloyed with other metals that could be dangerous due to their fumes. P.S. Found out later this guy had been high grading the nuggets off of a trommel belt and he had a few people looking for him after he moved out of the campground.


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## drfacefixer (Mar 8, 2013)

Viking said:


> I've delt with numerous acids over the years and the one that scared me the most was hydrofluoric acid, the calcium seeker. When I worked custodial/maintenance at the local school district they had a urinal/toilet cleaner named "Sixty Seconds" that had hydrofluoric acid in it and you didn't dare leave it on the surface of the porcelain longer than sixty seconds or it would cut right through the glass surface of the porcelain. Seems to me that I remember that it was taken off the market because it was so dangerous to handle, I remember reading that hydrofluoric acid would go through the skin and directly to the bones. About seven years ago while down in N. Nevada for gold detecting I saw a guy using pure hydrofluoric acid to remove quartz from large gold nuggets, I warned the guy but he didn't seem too concerned, but then he wasn't in the best of health as it was. Any smelting should be done where you don't breath fumes, gold and silver are often alloyed with other metals that could be dangerous due to their fumes. P.S. Found out later this guy had been high grading the nuggets off of a trommel belt and he had a few people looking for him after he moved out of the campground.


Correct about HF acid. I commonly use it in glass etching. It is dangerous on any level but its the insidiousness of the acid that causes the injury. Its considered a much weaker acid that Sulfuric or Hydrochloric which immediately destroy any tissues it comes in contact with. As they burn some of the acid is neutralized from protein coagulation. However, with HF acid, it can leach through the epidermal layers without causing a high degree of pain until it causes potassium leakage in deeper tissues and exchanging calcium in hard tissues. The hallmark of treatment in neutralization which depending on the contact time and severity of spill can mean continual application of calcium guconate gel to the tissues or calcium injections. Unfortunately, the best indicator for neutralization is the resolution of pain. Because of this, you can't give pain medication nor local anesthetic for the burns because it is your main guide to directing treatment. The immediate danger of HF acid is electrolyte disturbances severe enough to cause cardiac dysfunction. Also like most acids, the fumes can also trigger laryngospasms (involuntary closure of the airway) which cause pulmonary dammage or death depending on the severity.


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## Viking (Mar 16, 2009)

Talking about etching glass reminded me of a passage written in a book called "Generation of Vipers" by Phillip Wylie, seems he had an issue with moms as he wrote (from what I remember) "Dear mom, sweet mom whose very urine would etch glass." she must have had hydrofluoric acid for pee.


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## smaj100 (Oct 17, 2012)

Here's an honest question, I have a bunch of aluminum car parts left over from recent repairs and want to melt them down into manageable ingots. What kind of strength will this have? Is there different qualities from Al, what makes T6 Al different then say a bunch of scrap or Al cans melted down?


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## LincTex (Apr 1, 2011)

smaj100 said:


> Here's an honest question, I have a bunch of aluminum car parts left over from recent repairs and want to melt them down into manageable ingots. What kind of strength will this have? Is there different qualities from Al, what makes T6 Al different then say a bunch of scrap or Al cans melted down?


Looks like they are 3xxx series aluminum, excellent corrosion resistance and weldability.

http://en.wikipedia.org/wiki/Beverage_can

Composition
Most metal beverage cans manufactured in the United States are made of aluminum,[4] whereas in some parts of Europe and Asia approximately 55 percent are made of steel and 45 percent are aluminum alloy. Steel cans often have a top made of aluminum. The aluminum used in United States and Canada are alloys containing 92.5% to 97% alumina, <5.5% magnesium, <1.6% manganese, <0.15% chromium and some trace amounts of iron, silicon and copper according to MSDS from aluminum producer Alcoa.[5] Alloys used include 3004, 3105, or other 3xxx/5xxx series aluminum.[6]

When recycled without other metals being mixed in, the can-lid combination is perfect for producing new stock for the main part of the can-the loss of magnesium during melting is made up for by the high magnesium content of the lid. Also, reducing ores such as bauxite into aluminum requires large amounts of electricity, making recycling cheaper than producing new metal.

0, -T3, -T6 etc. are NOT an alloy designation... it is a heat treatment after it is forged or extruded. The four digit number (3003, 5052, 6061, 2025, 7075) will tell you what other elements (copper, magnesium, manganese, etc) are alloyed with the aluminum to get the proper mix, then the suffix is the treatment.

-O temper aluminum has no heat treating
-T3 tempered
-T4 Solution treated and naturally aged
-T6 solution heat treated and artificially aged 
-T651 solution heat treated, stress-relieved stretched and artificially aged

etc. etc. etc.


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## Viking (Mar 16, 2009)

smaj100 said:


> Here's an honest question, I have a bunch of aluminum car parts left over from recent repairs and want to melt them down into manageable ingots. What kind of strength will this have? Is there different qualities from Al, what makes T6 Al different then say a bunch of scrap or Al cans melted down?


You basically end up with a mix that might end up good for casting valve covers for your favorite hot rod engine, that's what a friend of mine used to do back in the 70's. He figured the amount of shrinkage involved and made his own sand cast form and took it and the scrap aluminum to a smelting shop. The castings turned out looking professional at a lot less cost than from suppliers, not only that but he had them made for a "Nail Head" Buick engine which fancy valve covers may not have been available for at the time.


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## LincTex (Apr 1, 2011)

In the movie "World's Fastest Indian" they show Burt making a cast piston for his bike from broken pistons from cars. "Two parts Chevy, one part Ford" to make his custom alloy 

It would be a lot of work to get the metallurgical data from the car manufacturer of the part being scrapped. It would be best to look for foundry markings on the part itself (Alcoa, Kaiser, etc.) and then ask the foundry what offerings they have for castings.

Newer style car pistons have a LOT of silicon (not silicone) in them. That makes them very strong but also brittle. Be careful what parts you cast with melted pistons, you may have a part that will crack very easily if the casting process isn't done perfectly. High "Si" numbers also means your tooling needs to be super sharp if you do any machining.


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