# Acetylene/Oxygen Torch Maximum Capacity to Melt?



## autumnwillow (Apr 12, 2016)

I did an inquartation today, 125g gold 375g silver, lots of borax/soda ash and some nitre.
Tried the brazing tip, on neutral flame, almost an hour already, no melt.
Tried the cutting tip, on neutral flame, 10 mins at work and the nozzles where showing signs of carbon build-up. I was able to fix this by increasing the acetylene pressure.
Took me about 20 minutes to melt the 500g lot.

I do not have a rosebud tip yet. Does any of you have one? What was the maximum lot you melted and for how long?
I ask because acetylene should not be used for more than 1/7 of its capacity per hour. And we are talking minutes here.

Would I be better off with propane/lpg and oxygen tip? Propane/LPG produces more heat output per BTU but at lower temperatures.


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## Barren Realms 007 (Apr 12, 2016)

Why try such a large lot at one time when you seem to have little experience in doing this? If you are able to make our melts smaller sized. Do you have your melting dish setting on some sheetrcok or fire blanket? 
the base that the melting dish is setting on might be acting as a heat sink.
I picture of your setup would help with finding your problem.


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## autumnwillow (Apr 12, 2016)

I'm trying to test the capacity of the torch because I will processing larger lots than this.

It could probably melt up to 1kg with this cutting tip, but how about the rosebud tip? This cutting tip is not good as the area it heats is very concentrated.


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## Barren Realms 007 (Apr 12, 2016)

The bricks you have the dish setting on are acting like a heat sink and not allowing your material to heat up correctly. I would find a single element electric hot plate to put that on to heat up the dish and material. Your torch should be big enough to do the job. If you are going to be doing larger jobs than this you should consider going to a gas fired small furnace and some good salamander graphite crucibles that will last you for a while. You also don't need much flux, just enough borax to coat the surface of the dish.


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## autumnwillow (Apr 12, 2016)

I need to perform some sort of cupellation in order to get rid of some of the base metals. This is why I use soda ash so I could remove the slag easier and nitre to oxidize some of the base metals. I do not want to end up having this kind of trouble: http://goldrefiningforum.com/~goldrefi/phpBB3/viewtopic.php?f=53&t=20921&p=215294#p215294

Do you own an oxy/acetylene setup? What was the most that you have melted, for how long and what tip did you use?
Getting a furnace is currently out of the budget.

I totally agree that the heat is being transferred somewhere. The room is cooled by an air conditioner, although there is a door that I could shut to restrict the air conditioning, I'm a bit scared that if something goes wrong the person carrying the fire extinguisher will have less time to extinguish me. lol


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## Barren Realms 007 (Apr 12, 2016)

Yes I own an oxy/acet torch. But I do the majority of my melting with a MAPP gas torch. I can melt as much as 5 Toz of gold with my MAPP gas torch.

What kind of material are you trying to process? Karat gold or something else?

[youtube]http://www.youtube.com/watch?v=e4jjOmUrWpo[/youtube]


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## autumnwillow (Apr 12, 2016)

Karat gold.

Why do you prefer your mapp over oxy/acetylene? You could have saved 3 to 4 minutes of time.


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## Barren Realms 007 (Apr 12, 2016)

autumnwillow said:


> Karat gold.
> 
> Why do you prefer your mapp over oxy/acetylene? You could have saved 3 to 4 minutes of time.



Because it is what I like using.


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## Anonymous (Apr 12, 2016)

Mapp is great Willow. It's got it's limitations in how much you can melt at a time but given the cost of the Mapp setup vs the cost of the Oxy/Acetylene setup it's definitely got its place in the scheme of things. I use both, selecting which one based upon the size of the melt, and whether I am pouring a bar or making a button.


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## g_axelsson (Apr 13, 2016)

Most often problem with melting stems from excessive heat loss rather than too little heat added.
Your setup is an example of that.

Look at this thread, http://goldrefiningforum.com/phpBB3/viewtopic.php?f=61&t=19840#p201990 and see how I built up a small cave, almost like a small furnace. The firebricks around the melting dish reflects the heat and makes it really easy to melt the gold.
I used LPG and air and melted 53 g of gold in probably less than 10 minutes.

Add a ceramic blanket below the melting dish, put some fire bricks around to reflect the heat and possible direct the air flow so it hits the dish more than once. If you do that it should be a lot easier to melt.

Göran


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## mls26cwru (Apr 13, 2016)

I use a oxy/propane torch... cost wise, it is cheap, but i have not tested the capacity or gotten different tips yet though.


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## autumnwillow (Apr 14, 2016)

Okay. I think I'll build a refractory cement hood with a small exhaust then with a silica sand base to hold the crucibles just for torch meltings or maybe just a bunch of firebricks (like a fireplace). Those are firebricks by the way.


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## joekbit (May 5, 2017)

Well I use a standard oxy-propane setup with a #2 cutting tip set as low as I can get it without it popping off. Put my dish on a fire brick with no base heat and preheat the dish till my flux is fluid, it only takes about a minute, then I add my powder for the melt. 

With the flux in its sticky / melted state it grabs the powder like glue preventing it from blowing out of the bowl 

I posted an image of my last melted button of 129.17 grams fine gold, assay 99.8. time to melt was about 3 min. powder to button weight spot on, no loss from blowing Au out of the dish.

Sorry no video of the actual melt .

I like the oxygen propane because it burns far cleaner, no soot or carbon, plus propane is cheap. I get 20lbs for 6 bucks.


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