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Author: Subject: Can butane melt silver?
Foeskes
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[*] posted on 5-1-2018 at 21:43
Can butane melt silver?


I extracted some silver from a bracelet I bought. Not its a gray powder. After converting to silver nitrate I used copper to extract the silver as a powder then remove the large chunks of copper then put the remaining silver in HCl/H2O2 mix to remove any copper contamination. I am left with a grey silver powder drying in a desecator. I am planning on melting some of it for my element collection since it's kinda dull(likely from the HCl and H2O2). I only own a butane spiral flame torch(kovea brand) my country seems to not sell many torches, just this one and those ones you commonly find channels on YouTube burning household items for some reason. Propane and mapp gas torches are impossible to find. The only other torch I can find are oxy LPG and oxy acetylene, which I don't own and are expensive.
So I am curious if it's possible to use a low setting on the torch on a small amount of powder(<1g) to avoid blowing it.
Here's the torch I have: http://kovea.com/product/brazing/

[Edited on 6-1-2018 by Foeskes]
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[*] posted on 5-1-2018 at 21:57


Just barely in my experience.



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[*] posted on 5-1-2018 at 23:32


Found this, http://juxtamorph.com/butane-versus-propane-which-is-hotter/
They compare btu from butane and propane torches. They specifically mention melting silver on a piece of charcoal as a direct comparison for heat. Propane wins, but both will do the job.

[Edited on 6-1-2018 by violet sin]




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[*] posted on 6-1-2018 at 06:02


I have melted silver with a small butane torch before. It takes a while, but you get there.



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[*] posted on 6-1-2018 at 06:55


I have also melted silver with Propane though. I found it helps if you put some insulating white fire brick type things around it, i made a little igloo like thing, this helped keep the heat in.

I managed to melt a fork and spoon made from silver with a smallish torch and separate gas bottle.
Technique must also play a part in this, if you think about it we have had both the Bronze and iron age. I doubt they had much access to butane or Propane, i suspect they had more access than we do in Scotland though :D
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[*] posted on 6-1-2018 at 07:35


Butane has about the same flame temp (and a higher heat value) as propane, just under 2000C. Silver melts below 1000C. Make your heated space adiabatic, and you should have no problems.




[Edited on 1/6/18 by PirateDocBrown]




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Foeskes
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[*] posted on 6-1-2018 at 17:15


Just tried melting a small amount of it it melted no problem.
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[*] posted on 7-1-2018 at 05:16


good to hear but if all ells fails go with the millennia tried and true method charcoal and a fan!
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[*] posted on 7-1-2018 at 06:35


You can melt silver in a candle flame.
If you are planning to melt powdered silver you might want to add a flux to stop it blowing around too much.
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[*] posted on 7-1-2018 at 06:40


If you have silver nitrate, heat it to 440 C for total decomposition to elemental Ag.
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[*] posted on 7-1-2018 at 12:25


My experience with a stove's methane flame is that perturbing the flame (by moving the lid slightly generating a very noisy flame) generates a hotter flame (able to melt zinc) while heating something placed into the flame.

Some supporting theory, see https://link.springer.com/article/10.1134/S0010508211040046 . To quote:

"It is found that the deceleration of the flow in the vicinity of the thermocouple leads to a local increase of heat due to chemical reactions and the corresponding increase in temperature relative to the thermocouple unperturbed value."

which I take as meaning burning CH4 more completely in air, due to perturbation, produces more effective heating.

[Edited on 7-1-2018 by AJKOER]
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[*] posted on 7-1-2018 at 12:38


Quote: Originally posted by AJKOER  
My experience with a stove's methane flame is that perturbing the flame (by moving the lid slightly generating a very noisy flame) generates a hotter flame (able to melt zinc) while heating something placed into the flame.

Some supporting theory, see https://link.springer.com/article/10.1134/S0010508211040046 . To quote:

"It is found that the deceleration of the flow in the vicinity of the thermocouple leads to a local increase of heat due to chemical reactions and the corresponding increase in temperature relative to the thermocouple unperturbed value.

[Edited on 7-1-2018 by AJKOER]

It would be quite hard to think of any common flame that does not reach the 420C or so needed to melt zinc.
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[*] posted on 7-1-2018 at 12:38


Quote: Originally posted by AJKOER  
My experience with a stove's methane flame is that perturbing the flame (by moving the lid slightly generating a very noisy flame) generates a hotter flame (able to melt zinc) while heating something placed into the flame.

Some supporting theory, see https://link.springer.com/article/10.1134/S0010508211040046 . To quote:

"It is found that the deceleration of the flow in the vicinity of the thermocouple leads to a local increase of heat due to chemical reactions and the corresponding increase in temperature relative to the thermocouple unperturbed value.

[Edited on 7-1-2018 by AJKOER]

It would be quite hard to think of any common flame that does not reach the 420C or so needed to melt zinc.
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[*] posted on 7-1-2018 at 12:47


Reduction in heating time can translate into success or failure if you are unsure of feasibility and are physically positioning the item in the flame.

Zinc melts around 420°C/788 °F, while Silver at 962 °C/1,763 °F. Perturbing the flame may be a good start.

[Edited on 7-1-2018 by AJKOER]
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[*] posted on 7-1-2018 at 14:29


What a weird discussion.

I've personally melted Gold with a butane & oxygen torch - it's the hottest thing i have.

The instantaneous flame temperature of whatever gas you got depends very much on the amount of oxygen you got as well, so saying 'acetylene is hotter than butane' is rather useless, unless the ratio of gas/oxygen is also the same, such as 20% in the case of Air at STP.

There is a simple reason they use pressurised oxygen & acetylene torches to melt steel - it burns hotter than just acetylene in air.

This butane/oxygen torch also melts steel, just not as fast as an oxy-acetlyene rig, nor as large an amount.




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[*] posted on 7-1-2018 at 20:12


Adiabatic flame temperatures:

Acetylene Air 2500
Acetylene Oxygen 3480
Butane Air 1970
Ethane Air 1955
Ethanol Air 2082
Gasoline Air 2138
Hydrogen Air 2254
Hydrogen Oxygen 3200
Methane Air 1963
Methanol Air 1949
Natural gasAir 1960
Pentane Air 1977
Propane Air 1980
Propane Oxygen 2526
MAPP gas Air 2010
MAPP gas Oxygen 2927
Toluene Air 2071
Kerosene Air 2093




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[*] posted on 8-1-2018 at 16:47


Yup. The butane or propane, you are using, is about as good as anything. Just need a better delivery system. Better torch. One with oxygen input.

The extra ingredient you need.... is compressed air, or oxygen.

A muffle furnace, operating even on only methane/air, has no problem, melting industrial amounts of Silver for casting.
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[*] posted on 9-1-2018 at 06:03


Quote: Originally posted by Foeskes  
I extracted some silver from a bracelet I bought. Not its a gray powder. After converting to silver nitrate I used copper to extract the silver as a powder then remove the large chunks of copper then put the remaining silver in HCl/H2O2 mix to remove any copper contamination. I am left with a grey silver powder drying in a desecator. I am planning on melting some of it for my element collection since it's kinda dull(likely from the HCl and H2O2). I only own a butane spiral flame torch(kovea brand) my country seems to not sell many torches, just this one and those ones you commonly find channels on YouTube burning household items for some reason. Propane and mapp gas torches are impossible to find. The only other torch I can find are oxy LPG and oxy acetylene, which I don't own and are expensive.


So I am curious if it's possible to use a low setting on the torch on a small amount of powder(<1g) to avoid blowing it.
Here's the torch I have: http://kovea.com/product/brazing/

[Edited on 6-1-2018 by Foeskes]


After removing the copper you are left with silver chloride, that's why it's so dull. Add a little Karo syrup to keep the silver chloride from blowing everywhere. This also helps reduce the silver chloride to silver metal.

[Edited on 9-1-2018 by hyfalcon]
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[*] posted on 9-1-2018 at 06:24


Quote: Originally posted by aga  

The instantaneous flame temperature of whatever gas you got depends very much on the amount of oxygen you got as well, so saying 'acetylene is hotter than butane' is rather useless, unless the ratio of gas/oxygen is also the same, such as 20% in the case of Air at STP.

There is a simple reason they use pressurised oxygen & acetylene torches to melt steel - it burns hotter than just acetylene in air.

The temperature of the flame obviously depends on how much air is present. And most torches are designed to run near the optimum air/ fuel mixture.
One advantage to a compressed air driven flame is that you can vary the air flow directly.

There's a reason they use acetylene for oxy acetylene torches too.
It can carry more energy (per mole of oxygen consumed) and so it burns hotter. Using oxygen rather than air has one other major benefit; you don't waste energy heating up the nitrogen (and argon etc).
And the hotter flame does a better job of transferring heat to the metal.
Obviously, the work-piece is always "trying" to cool down and so there's a balance struck where the rate of heating and cooling match.
If you have a hotter flame that balance (for a given power) is reached with a hotter work-piece.
And that can make the difference between "hot enough to melt" and "not hot enough to melt".
A torch with a bigger flame burning more fuel would also affect that balance.
So (as people have pointed out) does some sort of enclosure round the work.

(And, as is often the case, I don't think it's clear what AJKOER was trying to say. If he's struggling to melt zinc (at 420 C) with a methane flame that burns at up to 1900C or thereabouts then he needs a better technique, rather than a better fuel)

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[*] posted on 9-1-2018 at 14:21


Now, if you have an old microwave oven or two, and a lantern battery, you might want to try this. https://www.youtube.com/watch?v=VTzKIs19eZE
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[*] posted on 9-1-2018 at 14:51


Quote: Originally posted by zed  
Now, if you have an old microwave oven or two, and a lantern battery, you might want to try this. https://www.youtube.com/watch?v=VTzKIs19eZE

If I really need a arc furnace I think using a comercial arc welder is safer than winding a transformer.
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[*] posted on 9-1-2018 at 18:56


What? You don't want to be electrocuted?

Perhaps you have a point.

Once upon a time, jewelers might create a small bead of metal, or solder......via use of a blowpipe.

Just a small breath powered metal tube, and a candle or a spirit lamp, provided the required heat.

Some folks still do things that way. Though our friend here, is more high tech than many. https://www.youtube.com/watch?v=JSAXcjh3m30&t=14s
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