# Deposited Silver - Fixer



## Shrek (Sep 12, 2013)

Hey everyone,
Just a quick question. I'm using zinc reduction to get silver from used fixer solution - very standard procedure. I use glass containers inside which the solution precipitates. After I have decanted and added HCl to the remainder, what is the best way to remove residue from the container? There is metallic residue all over the sides and bottom of the container. What method do you guys use to get this out of the container and into the crucible?


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## etack (Sep 12, 2013)

I would use water to rinse the sides and let it settle you may need some dish soap to help. just a drop. then pour off the water dry it the way you like, then pour into your melting dish.

when you rinse with the HCl mix well and let the acid work.

Eric


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## Shrek (Sep 13, 2013)

etack said:


> I would use water to rinse the sides and let it settle you may need some dish soap to help. just a drop. then pour off the water dry it the way you like, then pour into your melting dish.
> 
> when you rinse with the HCl mix well and let the acid work.
> 
> Eric



Hi Eric,
I rinsed the sides with water and it did the trick, thank you very much.
I've mixed the remainder with acid. From here, is it okay to filter it in filter paper and then put the product straight into the crucible?


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## etack (Sep 13, 2013)

Shrek said:


> etack said:
> 
> 
> > I would use water to rinse the sides and let it settle you may need some dish soap to help. just a drop. then pour off the water dry it the way you like, then pour into your melting dish.
> ...


 After all the zinc is removed rinse well again and the melt.

Eric


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## Shrek (Sep 17, 2013)

etack said:


> Shrek said:
> 
> 
> > etack said:
> ...



Okay, I'm currently at the position where I have some silver sludge, and I'm looking to melt it. I have searched the forum, but I've not been to able to find a definitive answer: what's the best (most economical but effective) method of melting all of this? Would a blowtorch be a good idea?


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## Lou (Sep 17, 2013)

Contingent on quantity:

grams to a few ounces...handheld propane or MAPP torch and a small melting dish made of silica or kaolin clay
few ounces to 10-15 ounces...oxyfuel torch
10-1000s of ounces...build a crucible furnace, preferably one that tilts.


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## Shrek (Sep 22, 2013)

Lou said:


> Contingent on quantity:
> 
> grams to a few ounces...handheld propane or MAPP torch and a small melting dish made of silica or kaolin clay
> few ounces to 10-15 ounces...oxyfuel torch
> 10-1000s of ounces...build a crucible furnace, preferably one that tilts.



So I tried to melt around 10 grams of product as a test. It was unsuccessful, and I'm not sure why. If you take a look at the attached picture;
- I tired to melt it using coal before I asked on the forum, which didn't exactly work... :lol: I did end up with some very dry solid though.
- I tipped some borax into a mould and tried to melt it (the crucible I got was way too big so I couldn't really use it here). The borax DID melt for a second, and then it all started bubbling back and became a white solid again.
- what I ended up with is some yellow-grey flakes which I had from the crucible, with some metallic specks on the surface. I'm guessing it's silver, but I'm not really sure.

So, what happened here? Is it AgCl which I have? The yellow-grey stuff? And why didn't the borax melt?
Any help would be greatly appreciated, I'm pretty confused


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## FrugalRefiner (Sep 22, 2013)

Shrek said:


> Lou said:
> 
> 
> > grams to a few ounces...handheld propane or MAPP torch and a small melting dish made of silica or kaolin clay
> ...


The reaction of the borax when heated is to be expected. I'm assuming you were using something like 20 Mule Team borax. Water is a component of the borax. When heated, the water is driven out of the matrix and as it expands it bubbles as it did for you. Once the water has been driven off, further heating will cause the borax to melt into a smooth liquid.

However, I don't know that you'll ever get to that point in a graphite mold. Lou suggested a melting dish for a reason. Melting dishes are for melting. Molds are used once your material is melted. Graphite is a pretty good conductor of heat. As fast as you're heating it with your torch, the heat is being conducted through the mold and radiated away from the outside.

You can experience similar problems even with a melting dish. To avoid the problem, set the melting dish on a piece of ceramic blanket like kaowool. It is an insulator and will help to hold the heat in where you want it.

Dave


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## Shrek (Sep 22, 2013)

Okay, thank you very much, next time I'll definitely use a melting dish instead.
Other than the graphite mould, does the stuff I'm melting look normal? Is that how the products of zinc reduction are supposed to look when melting?
And for how long would you normally heat it before it melted?


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## FrugalRefiner (Sep 22, 2013)

I've never cemented silver from fixer with zinc, so I can't opine as to whether your result looks normal or not.

As far as how long it takes to melt, that depends on a lot of variables. 
How much material is being melted?
What kind of torch (not just propane vs. MAPP, etc., but the torch model itself)? I have a propane torch I use to sweat copper plumbing fittings that will barely melt a few grams of silver. I have another propane torch that will melt copper. It's mostly a matter of how much propane can flow through the torch.
Are you adding oxygen?
What is the ambient temperature?
Is it calm or windy?
Are you melting on ceramic wool or another insulator?
Probably a few others that I'm not thinking of at the moment.

So if you're using a small orifice propane torch, on a cold, windy day, with the melting dish out in the open, it will take a lot longer than if you're using an oxy/gas torch on a warm calm day with the melting dish sitting on a layer of ceramic blanket. Sorry I can't be more specific, but there are too many factors at play.

Dave


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