# Help with melting silver after electrolysis



## svarbanu (Jul 7, 2014)

Hi members

I need your expert advice on choice of crucible and flux to be used etc for melting silver after electrolysis without compromising its purity.


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## solar_plasma (Jul 7, 2014)

For pure silver: Glaze a clay crucible or melting dish with borax. Then melt the silver without any extra flux. To set up some walls to the side for reflecting the heat are almost mandatory, glass wool beneath and around the crucible makes it much easier to get a good heat. Start heating by surrounding the silver with your flame, that makes it denser and cling together, so that it isn't blown away by the flame.

Everything has to be as clean as possible, even the torch.


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## svarbanu (Jul 8, 2014)

Ok Tnx. Will try this method.


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## svarbanu (Jul 13, 2014)

Hi guys . 

i tried melting cemented silver. But it didnt turn out good .



I used this torch

Fuel was cigaratte lighter refill.

I guess the temp was not enough. Please recommend the right type of gas . Can i melt silver using charcoal furnace. amount to be melted is around 100 gms.

I also have this torch


But i dont know how to use it. I saw a bold tightly screwed up inside the nozzle which i loosed a couple of turn.



Is this the right way? can i hook this with an lpg cylinder and achieving melting?
Pls help a noob.


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## goldsilverpro (Jul 13, 2014)

svarbanu said:


> Hi members
> 
> I need your expert advice on choice of crucible and flux to be used etc for melting silver after electrolysis without compromising its purity.


What type of electrolysis? Cyanide? Sulfuric acid? Nitrate? Or, what?


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## svarbanu (Jul 14, 2014)

I used nitric acid to dissolve silver(mostly custom made jewellery) and pure copper rod for cementing.


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## kadriver (Jul 14, 2014)

I use oxy/acetylene with the flame set very low (no hiss or sound of any kind from the flame) using a cutting torch head.

I can melt 5 Troy ounces of pure silver in about 3 or 4 minutes. One Troy ounce in about a minute.

Some folks also use oxy/propane. 

I bought my first oxy/acetylene torch complete kit, including small tanks, on sale at Harbor Freight for about $300 tax included back in 2010.

The regulators are cheap but they lasted about two years with heavy use.

Eventually the threads wore out on the regulators so I bought a nice medium duty cutting torch set from National Welders for $275 tax included - no tanks.

If you get an oxy/acet rig then make sure you never point the flame directly at the silver as it will vaporize the silver and cause loss of your metal

Concentrate the flame on the melt dish and use some ceramic wool under the dish to conserve heat.

Don't use fiberglass, it will just melt and stick to the dish.

Hope this is helpful to you.

kadriver


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## maynman1751 (Jul 14, 2014)

Thank You Kevin for those helpful hints. 8)


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## Claudie (Jul 17, 2014)

What kind of crucible are you using. The photograph almost looks like the mortar from a mortar & pestle set. 
Also see this post from http://goldrefiningforum.com/~goldrefi/phpBB3/viewtopic.php?f=63&t=9943



eeTHr said:


> snowfrmee2day said:
> 
> 
> > ok here is the beginning to present
> ...


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## Palladium (Jul 18, 2014)

Kevin, have you looked at building you a furance yet?


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## Ollie1016 (Jul 18, 2014)

I use paint can furnaces with a propane torch. Works a charm. I can melt 300g of silver in 7 minutes and 300g of copper in 25/30minutes. All I use for refractory is perlite, sand and regular cement. 

It does break down and crumble. But it only takes 10 minutes to make a new furnace and the materials are basically free for me! 

I can put some pictures up if you want


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## Claudie (Jul 18, 2014)

I would be interested in seeing some pictures.


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## kurtak (Jul 19, 2014)

pictures are always good

Kurt


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## Palladium (Jul 20, 2014)

I've recently decided to build one myself considering i have to much silver to melt by torch now. Years ago i use to build industrial furnaces, but i have never built a crucible one. This has been a new experience for me a little, but has been fun. Total cost to build? Maybe $100. $200 counting all the tongs, molds, and such. Only fired one time so far to test the burner. I still have a burn in to do before it's ready to run. It's been drying about two weeks now. I still have wheels to go. Total weight? About 175 lbs.


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## maynman1751 (Jul 20, 2014)

Dang Palladium! That's a beauty.


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## Claudie (Jul 20, 2014)

You sure do nice work. That looks very nice.


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## Harold_V (Jul 21, 2014)

Real pretty work, Ralph, but that wooden beam isn't going to work out for you. It's going to get incinerated quickly when the furnace is fired. The vertical member may be fine, depending on if you have leaks at the interface of the lid and furnace. As slag builds up, you may find you lose a lot of heat there, too. 

Harold


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## lazersteve (Jul 21, 2014)

Ralph,

You did a good job on the casting of your refractory and your furnace is also very roomy. Very nice work.

I have a few suggestions/comments:

1) Invest in a much larger propane tank to feed the beast. The small household tank shown in your photo is going to run out very quickly feeding your new monster. Lowes sells a nice 100# + tank for a around $120.

2) Change your lift mechanism (Harold pointed out) as your horizontal wooden beam will quickly get toasted by the top exhaust. The top exhaust comes out like a jet engine in my furnace. I fear the top exhaust will quickly ruin the small chains (and possibly the other metal parts) too, since they are directly above the exit path of the top exhaust. The last thing you need is a failure of your lift mechanism while the furnace is at melt temperature.

3) Invest in some heavy heat protection gear as the furnace will be very hot when operational making charging and pouring task very dangerous. You'll likely need some heavy heat proof mittens and a good heat reflective face shield.

4) The large furnace will take a load of BTU to get up to temperature. My smaller one (about 1/3 to 1/2 the size of yours) takes 45 minutes to get up to temperature with the lid closed at 5 psi propane flow.

5) Add an adjustable PSI regulator with pressure gauge to the propane tank. I can't tell if you already have one from your photos, but if you don't you can find some relatively inexpensive ones on Bayou Classic's website if my memory serves me correctly. 

6) Line the bottom of your furnace with 1/4 to 1/2" layer of powdered bone ash. This will protect your refractory from overflows and spills, making clean up of the furnace a snap. This will also allow you to recover any metal spills easily.

7) If you haven't done it already, cast a small 3/4 to 1" thick x 3 to 4" diameter (slightly larger than your crucible base) puck of refractory material to place under the crucible and boost it up a little higher in the furnace. Your crucible should not rest directly on the bottom of the furnace during operation. 

I can't wait to see the bars you cast with the furnace.

Steve


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## Palladium (Jul 21, 2014)

Thanks for the tips guys. Where can i locate bone ash at in a local market segment? You're right the wood will differently get toasted. The wood was for mock up purposes so i can get an idea of my design. I like building things out of wood in the beginning because it is so easy to change around for design aspects. I traded 10 McDonalds sausage biscuits for about 600 lbs of refractory and started playing around with the idea of building me a furnace. I had an old induction furnace a customer gave me when he bought a new one and i started to just install it in my shop but my electrical service would have to be upgraded and i just don't feel like going through all that right now so i figured what the heck. Once i work out that this design is going to work i will cast another one and build the stand and arms out of some tubular steel and 1/4 plate that i have laying around. It's a lot easier to cut and weld one time than to make modifications midway through something so i always use wood as a mock up. I have some stainless 304 chain that i am going to use on the final design where you see the galvanized chain at now. Regular steel should never be sandwiched in between refractory. That was so i could get my patterns and measurements right. The burner i will use again. It's rated at 250-300,000 btu and will consume i think it was 6 lbs of propane an hour @ 30 psi if i remember right. I have several 100 lb tanks just sitting around doing nothing. The refractory is rated at 3200 F, is a medium weight non wetting castable, and has hot face properties as well as a high psi for crushing strength and impact resistance. Ill probably make the next one a little smaller being as how i only need to melt a couple of kg at a time for my silver cell here at the old shop. This one has a large chamber and i may use if for playing with aluminum. I have all the safety equipment, gloves. and aprons, from my aluminum furnace days. I still remember opening the doors on a United 466 furance, the doors are 14 ft wide by 10 feet high, and shoving 10,000 lbs of aluminum into a hot molten pool. To me it was like walking on the face of Mercury. People use to always tell me i had a great tan! What they failed to realize is that it was a tan from infrared heat and not the sun. It would cook you from the outside inwards in just a couple of minutes. I'm to old and it's to hot to be using a torch this time of year in Alabama now. lol


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## lazersteve (Jul 23, 2014)

Powdered bone ash can be found at most online assay/mining supply houses. 

Steve


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## rickbb (Jul 23, 2014)

I've been practicing on my silver melting technique and I get cleaner and nicer looking little bars with a MAPP gas torch than a oxy/acetylene or propane. I get the melt nice and liquid, and have a propane torch on the mold keeping it hot and burning up the O2 while I pour in it. I get clean bright bars with little to no oxidizing on the bar.

I do small quantizes in a melting dish that has a thin glaze of borax, haven't collected enough silver to need a furnace/crucible setup. Although I did try to lay one up with fireplace bricks and ceramic wool. It just didn't do well for me and unless/until I get the need to pour pound size or larger bars I'll stick to this method.


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## svarbanu (Jul 24, 2014)

Claudie said:


> What kind of crucible are you using. The photograph almost looks like the mortar from a mortar & pestle set.


I am using a graphite coated clay crucible. Sorry for the poor quality pics.

Can members please guide me on using the torch that i posted at the beginning? I see a screw tightly wound inside the nozzle which i loosed up a couple of screws. Is this the right way?


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## solar_plasma (Jul 24, 2014)

On those pics I can't see what type of burner it is. If it works like a bunsen burner, it is easier to light it, when the air injection is closed. Then you get a yellow flame. Once it is burning, you can open for air.


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## kadriver (Aug 18, 2014)

Palladium said:


> Kevin, have you looked at building you a furance yet?



So far I have been melting small amounts with precise weights to make individual bars. I like the control I get using an open face furnace (melt dish and an oxy/acetylene torch).


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