# gold melting with mapp gas?



## wavecrazed

Can i use map gass for melting brown gold powder in a cruiciable? I see it burns at around 5000 or 2500 maybe farenheight or celcius.


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## jimdoc

Yes, it will work.

Jim


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## glondor

I find that it takes very good insulation under and around your melting dish. I do not advocate this for others but this is what I do. I fill a 10 liter pail 1/2 full of warm water and put the mapp gas canister in it just before I melt and remove it as soon as I am done. This helps to keep the gas flow up as the liquid in the tank gasses off. It still can be slow.
As I am recovering and not refining I do get a slag type cover on the metal which prevents it from melting. I try to remove this with a graphite rod and it helps a lot. The exposed gold melts quickly from there. Clean gold does not have this issue.I melted 83 grams recovered gold this morning and it took over 1/2 hour. Slow but it works. Not the best option.


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## philddreamer

Glondor, I understand what your saying. This time of the year, as it starts to get colder, the gas in the tank doesn't build up to create enough pressure for a nice constant hot flame. I might try the warm water next time.

I used some old fire bricks & made this set up, with 2 propane torches; I can melt up to 12 oz of silver. I fire one torch, cover the dish with a brick & allow it to heat for 10 to 15 min, then finish melting with the second torch.
If I'm in a rush, (usually because I have to ship first thing in the morning),
then I'd use the mapp. 

Phil


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## wavecrazed

ok is the pressure going to blow the gold dust out of the cruciable?


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## philddreamer

Yes, it could. 
If you have a torch were you can regulate the flow of the gas, then start @ a low setting & keeping the torch @ a "safe" distance from the dust; as the the gold dust starts to get red hot, get the flame hotter & place the torch closer to the gold until it starts to melt. 
Keep a "close" eye & retrive the torch when you see any gold flying away.

You'll get the hang of it.

Take care!

Phil


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## Harold_V

wavecrazed said:


> Can i use map gass for melting brown gold powder in a cruiciable? I see it burns at around 5000 or 2500 maybe farenheight or celcius.


The word is crucible, not cruiciable. This is not mean to embarrass you---it's so you learn proper terminology. We strive for accuracy on this forum, so please accept my comment in the spirit in which it was offered. 

I'm concerned that you actually mean a crucible. While a crucible is a good choice for furnace melting, it is not a good choice for torch melting. You can't get the heat where it's needed when you use a crucible, unlike when you use a melting dish. The responses you've received all revolve around a melting dish, which is exactly what I recommend you use if you intend to torch melt. 

Hope this helps.

Harold


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## wade brenckle

Someone please define or post a picture of a melting dish. Harold said it would be better than a crucible for a torch,which is all I have access to now.


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## jimdoc

http://www.contenti.com/products/casting/170-710.html

http://www.ebay.com/itm/CRUCIBLE-MELTING-DISH-SET-CRUCIBLES-HANDLE-CARBON-ROD-/190536063221?pt=LH_DefaultDomain_0&hash=item2c5cd598f5


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## philddreamer

The pic above shows a melting dish. You can also go to Lazersteve's website, http://goldrecovery.us/pricing.asp and check the items list, he has melting dishes for sale.

Phil


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## Irons2

I melt gold with a regular Propane torch. I use a Kaowool furnace with 75 mm of insulation thickness. I can keep 4 oz of Gold in a molten state with the torch at about 1/4 volume, once it's up to temp. The Kaowool insulation is so efficient, I can put my bare hand on the outside wall with it going full blast.
It's just a basic Thermodynamics problem.


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## glondor

Re-Irons. Can we get a picture of your kaowool furnace ? It would be great to melt with propane. so much cheaper than Mapp.


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## Irons2

glondor said:


> Re-Irons. Can we get a picture of your kaowool furnace ? It would be great to melt with propane. so much cheaper than Mapp.


I'm in the process of rebuilding it at the moment. Too hot for a melt, but I will, as soon as it's ready.
Building one is pretty simple and actually cheaper than using Firebrick or refractory Cement. I used a 6 inch cylindrical form to wrap the insulation around. The first 2 layers are 1/2 inch Ceramic Blanket, rated at 2400*F. and the outer layer is 2" Kaowool. Moist Paper is wrapped around the form first. Being wet is important as it will shrink along with the ceramic slurry that is applied to the first layer. The paper allows the insulating cylinder to be easily removed from the form. I tried using a thick ceramic liner, applied as a paste, but it tended to crack due to expansion and contraction. Another problem with it was the increased time it took to heat all of that Mass. A thin liner works just as well. All it does is protect the Ceramic Blanket from effects of Flux. A thin wash, periodically applied with a foam brush will seal any cracks and reduce the amount of loose fibers being blown into the work area.
The bottom is made from a 2" wide strip of Ceramic Blanket wound around a ceramic cylinder to fit inside the outer insulating shell. I found that, unless Refractory Cement is applied to the strip, it will tend to sag over time. This go-round, I'm adding some re-enforcing wire as U-shaped pins of Kanthal 16 Ga. heating element wire. Nichrome or Stainless Steel would work as well, but I have the better part of a 5 Lb. spool of Kanthal-A1 handy.

The ceramic cylinder is made from refractory cement re-enforced with chopped Ceramic Blanket fibers applied to a cardboard tube from a roll of paper towels. The cardboard will burn away upon heating.

The lid is the same as the walls and sitting on fiber re-enforced Fireclay plate. Support for the plate is 3, 1/8 inch X 7" Ceramic coated Tungsten rods that began life as TIG welding electrodes. The Kaowool lid is separate from the Ceramic Plate. The weight of the plate is too much for the Kaowool to bear.

For A torch, I use an old Berz-o-Matic Mapp torch that is no longer in production. The new ones aren't worth the Money but I found a good substitute made by MagTorch, a dual use Mapp/Propane heavy duty one that puts out the heat when needed. I bought a couple since I plan to build at least one other furnace to hold a shotting crucible.
More later...


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## goldaa

I made one out of the material for microwave smelter. Used 1 inch pices of (fiber board ceramic) 6 of them stacked on top of each other with a soft brick top and bottom cut a hole in top brick and run small pipe on an angle to swirle the fire with a propane torch. made a small one like steves furnice works good on the scorifiers.


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## butcher

Irons it sounds similar to a ferriers forge I built for horse shoeing it looked simialr to these barrel type in these pictures, a homemade pipe propane burner got the horse shoes cherry red.

http://www.google.com/search?num=10&hl=en&site=imghp&tbm=isch&source=hp&biw=1024&bih=583&q=kaowool&oq=kaowool&gs_l=img.12...0.0.0.3344.0.0.0.0.0.0.0.0..0.0...0.0...1ac.VXd0CXNXUqs

http://www.flickr.com/photos/cmpalmer/6134416343/


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## philddreamer

Hi Richard!
That's an interesting design! That material you gave, is that KaoWool?

Thanks!
Phil


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## Irons2

philddreamer said:


> Hi Richard!
> That's an interesting design! That material you gave, is that KaoWool?
> 
> Thanks!
> Phil


Yes it is. The Ceramic Blanket is a high temp version of KaoWool. It is also available in a 2600*F rating. The best feature is the light weight of the furnace, it makes it easier to move and store when not in use. I purchased the insulation on fleabay.


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## butcher

The ceramic glass fibers and air space between it helps to insulate well, it also keeps the heat in well, I usually use the ceramic wool with other refractory like Sairset refractory cement, the light weight fire brick makes a good base, a small furnace of this design can be made with doors, and multiple burners if needed.

http://www.google.com/search?hl=en&q=sairset%20refractory%20mortar&rlz=1R2RNQN_enUS457&psj=1&bav=on.2,or.r_gc.r_pw.,cf.osb&biw=1024&bih=583&wrapid=tlif134267071221810&um=1&ie=UTF-8&tbm=isch&source=og&sa=N&tab=wi&ei=focHUKziKce4rQHhuMzWBA

Philddreamer, the stuff you had was the ceramic blanket, or fiber wool.


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## philddreamer

Thank you gentlemen!

Phil


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