# I can't melt the silver I refined



## WillGreen (Jan 14, 2013)

Hi All, 

It is incredible, but I still have the same problem! 
Let me explain it one more time. 
I refined silver in nitric acid. 
I take a bit of hot water, put the silver in it and pour nitric acid on it - as little as possible. 
The reaction takes place and after a while the liquid is deep blue. I add some more silver to it in order to deplete the nitric acid, bringing the flask to a boil. When there is really no reaction anymore, I filter everything. The silver is then dropped with copper. There is again a violent reaction, which goes on for some time. When it stops completely, I take the copper out and I filter and wash everything. After that the liquid is still a bit blue, so I use water to deplete it, pouring it off, filling it with water again, until the solution is completely colourless. I then pour off the liquid until some 400 ml remains (together with the 140 grs of silver cement) and I boil it for ten minutes. I then fill the flask again, let the silver sink, pour the liquid off to appr. 150 ml. and heat the flask up so that water boils away. I then put the flask in an oven to take the last vapour out. 
I made a lot of ingots in my life and I know how to do it. 
When I start heating the silver, it forms a crust. It sticks to the crucible - using borax doesn’t help one bit. It also forms a crust on top. With the gaz I am using (oxy-propane), I can easily melt 500 grs of silver - but this 80 grams of silver (I did it in two times) just does not melt. Eventually, the silver starts to boil under the crust and breaks free. So, I ‘collect’ as much silver as I can close to the mouth of the crucible, but there is still stuff floating on top of it - using a carbon rod does not help either. Eventually I pour the silver into a steel ingot, but it’s impossible to end up with an ingot that I can use - I cannot roll it. 
After the melt, the crucivle has black muck over it which is impossible to remove (except with a wheel). You cannot melt it and pour it out gently, as with borax. The silver has deep red-brown stuff on it which is very difficult to remove. 
I really do not know how to solve this. I am at a complete loss. 
I took some pictures. I hope I can post them. If not, can please someone explain to me how to post pictures? 

Best regards, 

Will


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## WillGreen (Jan 14, 2013)

Here is a picture of the crucible.


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## jimdoc (Jan 14, 2013)

Your pictures look like you didn't pay your electric bill.

Jim


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## mikeinkaty (Jan 14, 2013)

Sounds like you started with a silver alloy that had something unusal in it. 

Mike


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## WillGreen (Jan 14, 2013)

Mike: No. Silver, copper, a little bit of silver solder, nothing else, I'm sure.


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## NobleMetalWorks (Jan 14, 2013)

What flux are you using for the silver?

What is the crucible made of? Sounds to me your crucible is the wrong type, and may be leaching something into the flux that is affecting your silver in a negative way. If you know for a fact your silver is silver, and not German silver, or the Mexican silver that often is alloyed with nickel, then the only other things it could possibly be is the gas used for your torch, the flux and/or your crucible, with the crucible seeming the most likely suspect.

I know someone that had a graphite crucible that exuded a foaming white substance on the first fire without anything in it. When they called the company that made the crucible, they found out it was the binder that was used, evidently it was used to excess in this particular crucible which caused the issue.

Scott


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## Anonymous (Jan 14, 2013)

Firstly, your photos are almost completely black. They are too dark for anyone to make out anything.. at least on my end. Try to lighten up your images before uploading.

If you already dropped your silver and there is no more reaction and (or) no more copper, you should have just the silver, especially after the wash/rinse cycle.

From what you're saying, I suspect you don't have pure silver, or even silver at all. If it won't melt at all, you more than likely have something different, or you don't have the adequate fire/heat source to melt it. I'm new to actually refining silver, and I can do it without a hitch. Something is definitely wrong with either your material or your melting method/source or both.

If you've refined before and you can't get the silver to even melt, I suspect you are not dealing with silver. If you do indeed have silver, it's contaminated and (or) your fire source is flawed. Even with a bad crucible, the silver should melt. I'm not saying it's going to pour correctly, but it should at least melt.

Are you doing this in freezing temps?

Kevin


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## metatp (Jan 14, 2013)

WillGreen,

What is the source of your silver? I had similar issues when I was dissolving some silver contacts with some silver solder. The silver that dropped also took down some other contaminates that didn't really melt. I added a lot more flux than normal. This created a reddish brown "skin" on the top. I let it cool enough in the melting dish so that it was solid, but able to still remove it from the melting dish with melt tongs. I hen dropped it in cold water. Most of it cracked off when quench in water. I removed the rest of the flux with some pH down. I melted it again in another dish, and was able to pour it into a graphite mold. They ended up 98-99% pure.

Regards,
Tom


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## Palladium (Jan 14, 2013)

Try boiling a small sample in ammonium hydroxide with a water wash and see if that helps.


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## WillGreen (Jan 16, 2013)

Hello, 


Tom and Palladium: I do not have ammonium hydroxide, but I did what Tom said - most of the stuff cracks off indeed and I was able to melt the silver normally - although I messed up yet another crucible. 

Some other information: there is nothing wrong with the crucibles I use. They are made of fused silica. I buy them from Contenti in the US. There is nothing wrong with the silver either. I buy it from a bullion dealer in Germany. I trust them. The silver that I refine is pure silver - I make mokume gane; for test pieces, I make billets of either copper and fine silver or nickel silver and fine silver. There is no silver solder in it. There is no answer to this problem, except that the wash is not well done and that there is still some nitric acid or copper nitrate sticking to the silver cement - this is unbelievable, given how well I wash it, but it is the only remaining possibility. I actually smell some NOx compound when I try to melt the metal. This is a very stupid problem. Many people have told me in the meantime that they have no problem washing the silver. But I do. I do not know why. 

Best regards, 


Will


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## amitoha23 (Jan 16, 2013)

Hi will

i had this problem . try heating the silver to much higher temp . that will solve the crust issue . 
the red dots happaned when you put not very clean silver with flux .

i suggest that you clean your crucible with acetic acid (vinegar) until its white clean , than after washing the silver cement very good try to melt it with small bit of flux 
and heat it up more when it all ready meltdown .

hope this help .

Regards
Amit


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