# Smelting problem



## Chirou (Jul 8, 2018)

Hello newbie here, i got myself some butane torches they shoult get up to 1300 degrees celcius and melt my gold powder but it seems they don't get that high temperature. Anybody know what can i do to increase temperature? Already spent a lot of money for those and now i'm trying to figure out how to make them reach that temperature. Maybe building up a little furnace or something and then using butane torch will work? After few different tries i'm out of ideas what to do it looks like some gold smelted but it refuses to smelt corectly and join into one bead it more resembles some little nuggets.


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## g_axelsson (Jul 8, 2018)

The problem with failure to melt gold is often heat loss. Insulate the melting dish and it will work a lot better. The size of the torch would also matter, it's not only the temperature that decides if you can melt something.

Maybe you should show a picture of the melting dish and torch you are using. As well as your setup, that would make it easier to help you.

Göran


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## Chirou (Jul 8, 2018)

i will have to go to my garage to make one, but the torch i'm using is simple butane torch like shown on few YT videos, could there also be a possibility that i added too less of the flux ? i got myself stuff like that posted below. i will have night shifts in 2 days maybe i'll build something like a little furnace isolate it with some clay etc and try again. The worse scenario i will just have to buy better torch. I also tried using 2 torches, everything was glowing red, some of gold lets say melted a bit cause it came together in few limps and flux was bubbling a bit but still i don't think it was enoght. Or maybe really i added to less flux (as flux i use Baking soda + borax)


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## FrugalRefiner (Jul 8, 2018)

Chirou said:


> I also tried using 2 torches, everything was glowing red, some of gold lets say melted a bit cause it came together in few limps and flux was bubbling a bit but still i don't think it was enoght.


You need to get beyond red. See Furnace Temperature Colors.

As Göran said, the problem is usually heat loss. Your graphite dish conducts heat really well, so it will lose heat as fast as you can pour it on with your torch(es).

Dave


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## kernels (Jul 9, 2018)

Yep, as above, Graphite is not great, look for a fused silica crucible. MAP gas also works much better.


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## g_axelsson (Jul 9, 2018)

One way to make melting easier is to put up a reflecting surface. Heat radiating out is reflected by surfaces so a small cave of firebricks makes it a lot easier to melt. Check this thread for an idea of what I'm talking about.
http://goldrefiningforum.com/phpBB3/viewtopic.php?f=61&t=19840
I pushed the melting dish inside the cave and the gold melted very easy. The torch used LPG (gasol in Swedish) with air.

Another good way to ease melting is to get some fireproof insulation and put the melting dish in it. That will minimize the heat loss through the bottom of the melting dish.

Melting is like filling a leaky bucket, the level (temperature) is rising when you pour water (heat) into the bucket, but as soon as you turn off the water supply the water drains out.
The more water you have in the bucket the more it leaks until you end up with a steady state and as much water leaks out as you pour in. To get a higher level you can either pour more water in (getting a better torch) or plug the holes (insulate, reflect the heat).

Göran


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## cosmetal (Jul 9, 2018)

g_axelsson said:


> _*Melting is like filling a leaky bucket, the level (temperature) is rising when you pour water (heat) into the bucket, but as soon as you turn off the water supply the water drains out.
> The more water you have in the bucket the more it leaks until you end up with a steady state and as much water leaks out as you pour in. To get a higher level you can either pour more water in (getting a better torch) or plug the holes (insulate, reflect the heat)*._
> 
> Göran



Excellent analogy.

The torch you are using is a culinary torch. Normally, they are used to add finishing cosmetic touches to already cooked desserts or meats.

Using Goran's analogy, the "hose" you are using is too small to add enough "water" to overcome the "leak" in your bucket. The fuel source for these types of type of torches is usually butane. 

Patch your "leaks" as much as possible but still get a larger "hose" and better (hotter) fuel source. The transfer rate of your fuel is also important.

James


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## g_axelsson (Jul 9, 2018)

Actually it's almost the same thing, it's even called "heat flow" and it can be described physically by the same formulas. Just separate a few constants and the name of a few variables.

Heat flows from a hotter spot to a cooler spot through a solid object the same way as water flows from a higher point to a lower point through a tube.

... if we ignore convection of gases or liquids which can move heat a lot faster and in a very non-linear way. :mrgreen: But that is to go into finer details than necessary.

Göran


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## anachronism (Jul 9, 2018)

Use some plasterboard or gyproc as they call it in the US. Also buy mapp gas. Messing about with butane isn't getting you anywhere fast.


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## Chirou (Jul 9, 2018)

Thank you guys, i will try to make some insulation, i have to check how hard and how expencive it will be to get mapp gas torch in here. As far as i see now it's not even on the internet Polish sites theres only gas but it's very expencive more expencive than all chemicals etc. Thats why i really hoped to get it working with Butane torch as someone showed on YT cause it's easy to get here. 

But theres a chance to get LPG gas here with a torch will this be alright ? It says 1850degrees so it seems fine but it's better to ask you guys ^^ .


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## cosmetal (Jul 9, 2018)

anachronism said:


> Use some plasterboard or gyproc as they call it in the US. Also buy mapp gas. Messing about with butane isn't getting you anywhere fast.



MAPP is a trademark name https://en.wikipedia.org/wiki/MAPP_gas and is no longer available here in North America. It has been replaced by MAPP Pro. Original MAPP had some propane in its mixture. MAPP Pro has the propane substituted with propylene. MAPP Pro doesn't have the "kick" (BTU) that MAPP had.

James


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## cosmetal (Jul 9, 2018)

Chirou said:


> Thank you guys, i will try to make some insulation, i have to check how hard and how expencive it will be to get mapp gas torch in here. As far as i see now it's not even on the internet Polish sites theres only gas but it's very expencive more expencive than all chemicals etc. That's why i really hoped to get it working with Butane torch as someone showed on YT cause it's easy to get here.
> 
> But theres a chance to get LPG gas here with a torch will this be alright ? It says 1850degrees so it seems fine but it's better to ask you guys ^^ .



Check into an Oxy/Propane set-up. Harris http://www.harrisproductsgroup.com/en/Products/Equipment/Torches.aspx and ESAB (Victor) https://www.esabna.com/us/en/products/brands/victor/index.cfm make great rosebud torches specifically designed for propane use. Do not try to use a regular oxy/acetylene rosebud with propane - it won't work well.

Unless you have built a good "oven" to trap your heat, propane by itself takes too long to do the job. It (propane) needs an assist from either injected air or oxygen to work efficiently (faster).

Peace,
James


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## kernels (Jul 9, 2018)

Tools always cost money and good tools cost more money. Gold is worth US$40 per gram so it's worth investing in good tools when you are working with it. 

Buying a couple of kitchen torches may seem a bit cheaper, but if they don't work then it is just money wasted that could have been put towards a good setup.

See if you can find a BernzOmatic TS8000 kit in your country, it does the business.


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## anachronism (Jul 10, 2018)

Thanks James I appreciate that- I never knew that.


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## Chirou (Jul 10, 2018)

Well i found one seller with BernzOmatic TS8000 but it's hard to get fuel here + it costs like 1/4 of my paycheck without fuel and delivery. But it's really easy to get LPG here cause we use it in cars and if it could work it would be great, and LPG burner it's not cheap but affordable. And Oxy-Propane torches are similar price as LPG but oxy-propane set it's like half of my month earnings not mentioning that i'm spending a lot more then just half on just taxes and food. 
LPG is easy to get here almos everywhere. It gives 1200celcius - 1850celcius. And i guess now it's my only hope but it would be great if someone could confirm that it will work.
This BenzOmatic TS8000 as i see in USA costs around 48dolars and here it should cost around 200-250zł and it does cost 489zł. I found Propan-Butan(LPG) welding Torch here which is not easy but not really hard to get, 

I'll attach what i found available from torches. Maybe theres a chance
Great thing is that i get scraps for free and that i found HCl and HNO3 seller (which are hard to get especially HNO3 because of UE). The only step i got left is smelting but it turns out it would be a hell easier in USA or other country .


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## Shark (Jul 10, 2018)

Check this out, with the top toarch it will allow you to melt your gold. Pay particular attention to Lasersteves input, as his design is the oldest version I know of.

http://goldrefiningforum.com/phpBB3/viewtopic.php?f=40&t=7387&hilit=mini+furnace


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## nickton (Jul 14, 2018)

I had the same problem for a long time, and have finally broken through with a set up that works for me. I built a small smelting furnace using six soft 1" thick white furnace bricks I bought on Ebay, with free delivery for like $28.00 (I think), a handmade propane forge blowtorch tip for $50.00 or so (others go for $60-100), a high pressure regulator ($20 I think), a large almost full BBQ propane tank I found off a free BBQ ($0.00), some stainless steel mesh from a salvaged outdoor heating lamp ($0.00), and miscellaneous scrap steel pieces ($0.00). 
I was sure in for a surprise when I first thought a propane torch would do fine. I now also have a Mapp gas set up with the t-8000 Bernzomatic tip. I'd love to have an oxy acetylene kit too, like Sreetips uses, but I haven't found an affordable one yet. You have to keep looking and unfortunately shell out some dough. I found the small forge I made helps keep the heat in a smaller area, where it doesn't escape so quickly. I also have an entry level mig welder that I used to clad my forge in scrap sheet metal (from computers), so that it doesn't crumble. This was my fourth attempt at a forge I think. It takes what it takes. 

Here are some pictures. The forge looks a bit rough but it's solid. My welding skills are only adequate, and the black paint and extra refractory cement I put on surfaces peeled off in the heat. That refractory cement doesn't seem to work very well in my experience.


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## Platdigger (Jul 14, 2018)

Were is the exhaust?


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## nickvc (Jul 15, 2018)

If you are going to build a furnace using gas then try and create a swirl furnace, a round metal container with the flame entering near the bottom at an angle to make the flame circle round it, you need to add insulation to the inside and a lid with a vent hole will help with the speed of melting and retaining the heat.


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## cosmetal (Jul 15, 2018)

nickton said:


> . . . . .
> *Here are some pictures. The forge looks a bit rough but it's solid. My welding skills are only adequate, and the black paint and extra refractory cement I put on surfaces peeled off in the heat. That refractory cement doesn't seem to work very well in my experience.*



Not trying to beat you up, but, its a *furnace* not a *forge*.  

Forge - 
"A forge is a type of hearth used for heating metals, or the workplace (smithy) where such a hearth is located. The forge is used by the smith to heat a piece of metal to a temperature where it becomes easier to shape by forging, or to the point where work hardening no longer occurs."
https://en.wikipedia.org/wiki/Forge

Furance -
"A furnace is a device used for high-temperature heating. The name derives from the Latin word Fornax, which means oven. The heat energy to fuel a furnace may be supplied directly by fuel combustion, by electricity such as the electric arc furnace, or through induction heating in induction furnaces."
https://en.wikipedia.org/wiki/Furnace

Peace,
James


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## nickton (Jul 18, 2018)

Yes indeed. I meant a furnace of course. I had made a couple of round ones but they didn't work as well, though that was before I bought the torch tip and high pressure valve. I had to make this one square because I used bricks and was limited to the small ones I bought. This furnace is admittedly improvised, but it seems to work well. For the vent I just open the door a bit and can adjust the air flow. Also the perforated stainless steel I managed to roll into a tube permits air passage and I can push the tip in or out to adjust the flow. Surprisingly it seems to work quite well and is so small it heats up quick. Primitive yes, but effective. Maybe in a few months I will change my tune but I guess this is the level I'm at now and it's working for me. :mrgreen:


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## nickton (Jul 18, 2018)

By the way thanks for all the help from this forum. I don't mind being corrected at all, so don' t worry about that. It's taken me a while to absorb a lot of this information in a way that makes sense to my layman's mind.
I have never taken a chemistry class in my life and am trained as a carpenter, so I apologize for sounding amateurish, which I most definitely am.


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## Geo (Jul 28, 2018)

Lazersteve sold a small furnace made from two insulating firebricks. There was a cavity made by a wood router that a melting dish set on. It was cut with a chamber on the bottom and a hole to place a torch tip pointing inside. There was grooves around the edge of the dish so that the dish was sitting on four points. That way the flames could pass the dish into the top chamber. A second brick with a chamber cut out with a vent hole to vent the spent gasses was placed on top of the first brick.


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## Geo (Jul 28, 2018)

I don't think he sells them any more.


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## Geo (Jul 28, 2018)

Also, to clarify, you are not having smelting issues. You are having melting issues. There is a difference. Smelting is a process where you reduce metal salts in a furnace with reducing agents at high heats. You can also liquefy rock that has tiny particles of precious metals so that a collector and flux can be added to extract the metals. Melting is simply melting metal that is already in metallic form and is relatively pure (free of rock or silica).


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## TreySeaJax (Jul 30, 2018)

Kaowool is cheap and easy to work with


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## Chirou (Sep 29, 2018)

Hello it's me agai i got question about melting gold o got LPG 11kg gas with torch temperature gets up to 1800 degrees and the problem is i got one batch of gold with borax which was previously melted but temperature was too low to smelt gold will there be any problem with remelting it or should i add something or dunno crush it or something.﻿


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## FrugalRefiner (Sep 29, 2018)

Chirou said:


> i got one batch of gold with borax which was previously melted but temperature was too low to smelt gold will there be any problem with remelting it or should i add something or dunno crush it or something.﻿


I'm a little confused.

You say you have "gold with borax which was previously melted". What melted? Did the gold melt, or was it just the borax that melted?

Then you say the "temperature was too low to smelt gold". You weren't trying to smelt the gold, just to melt it. So, I'm guessing only the borax melted, not the gold?

Once we know what melted, the next question is do you have a lump of this material by itself, or is it stuck in some kind of melting dish or crucible?

Sorry to answer your question with questions, but we'll need some answers to give you good advice. In theory, you should be able to simply remelt it, but if you answer the questions, you may get a better answer.

Dave


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## Shark (Sep 29, 2018)

This is a good example to the saying "a picture is worth a thousand words".


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## Chirou (Oct 2, 2018)

Well i don't have a oportunity to take picture now, but i uset butane torch and it only metled borax and all gold powder inside only came up into few lets call it veins and refused to actually melt. And i was wondering if i got batch like that will i have any troubles melting it or just normally attempt to melt it.


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## FrugalRefiner (Oct 2, 2018)

Chirou said:


> i uset butane torch


This may be a language/regional issue. Some people use the terms butane and propane interchangeably. You'll probably struggle with butane. Propane or LPG can do the job, but you still need to insulate the melting dish well. MAPP is preferred by many. A propane/oxy or acetylene/oxy system is the fastest generally used. All benefit by insulating the melting dish so you can apply heat faster than it can escape.



> it only metled borax and all gold powder inside only came up into few lets call it veins and refused to actually melt.


If your gold is coming up into the borax the way you described, you're probably using too much borax. You should only need a light glaze on the surface of your melting dish.



> And i was wondering if i got batch like that will i have any troubles melting it or just normally attempt to melt it.


Do you have a different torch or set up now? If you had trouble melting it the last time, unless you change something, you'll probably have problems again.

You can either try to melt it again as it is, or you can dissolve the borax and start over with the unmelted gold.

Dave


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## Shark (Oct 3, 2018)

One of the things I have learned in trying to reach high purity is to pay close attention to how fast the gold starts to melt. I noticed that my best buttons start to melt very quick and evenly. When they seem to take a bit long (more like just a few seconds), when they take a bit long or start to melt more in a localized spot I know and have always been proven right in the lack of quality. Most impure gold takes more heat to melt.

One thing that is mentioned in the brick furnace post about Lasersteves is that it took about 15 minutes for it to do a good melt. I would think that is a sign that the gas is barely able to reach high enough temperature. Mapp gas will get notably hotter than propane or butane. I most often use oxygen and propane, but I have oxygen and acetylene as well.


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## grainsofgold (Oct 5, 2018)

gold powder you started with -

Was it pure gold from a refining process ?

If so, then why would you need to use a lot of borax to melt it?

Trying to understand what you started with and what you were trying to do ?


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## Chirou (Oct 8, 2018)

Yea i changed my set up from butane torch to LPG 11kg torch and i'm building small insulation "wannabe furnace" to keep temperature. 

Well in first try i got more powder after burning filters than i expected and it was kinda a lot for my little cruicible. And i didn't graze the dish as i should have done before atempting to melt gold. 
I don't really think that my first try was pure gold i'm sure i overdid and got some copper with it. 
Now i'm waiting for new batch to finish.


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