# Making a gas furnace...



## samuel-a (Apr 23, 2014)

https://www.youtube.com/watch?v=0XlCcQMRM9E

For some reason i can't embed videos... if anyone could do that, it will be wonderful.

Hope you like it.


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## butcher (Apr 23, 2014)

Interesting way to introduce gas to the furnace burner, also a neat idea with the variable speed fan.

The underwater camera shot with sound is amazing, I wonder how that was done without damaging the camera from water or hot metals...

As usual Sam, I love seeing your videos, they are always great.


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## rewalston (Apr 23, 2014)

I wasn't able to view the video, I have audio but no video. I've had no problem watching any of Sam's other videos though. Maybe a little stuttering, tried both the system default player as well as youtubes html5 player (chosen under settings on the video). Any ideas?


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## philddreamer (Apr 23, 2014)

Awesome video Sam!!! 8) 

Thanks!

Phil


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## g_axelsson (Apr 23, 2014)

Cool video, I like the idea of using ceramic wool as a furnace liner.

To embed the video just drop the s in the "https://..." like this

```
[youtube]http://www.youtube.com/watch?v=0XlCcQMRM9E[/youtube]
```
[youtube]http://www.youtube.com/watch?v=0XlCcQMRM9E[/youtube]

Göran


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## GotTheBug (Apr 23, 2014)

Loved it Sir. A mix of bentonite clay and sand as a refractory lining seems to help the ceramic last longer in my "little furnace". Excellent build I think! Looks like you had it up to enough temp at one point to "remove" the paint on the outside of the pail also.


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## rewalston (Apr 23, 2014)

Go figure the video wouldn't play on youtube, but I can watch it just fine from Goran's post...

Rusty


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## Irons (Apr 23, 2014)

g_axelsson said:


> Cool video, I like the idea of using ceramic wool as a furnace liner.
> 
> To embed the video just drop the s in the "https://..." like this
> 
> ...



Goran,
I have found that Flux vapors quickly degrade the Ceramic Fiber. It becomes brittle and just crumbles away. Coating the inside with a Refractory Clay wash solves the problem.

Great Vid, Sam. I like the holes in the crucible to pour shot. Clever.


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## etack (Apr 23, 2014)

I have to agree with Irons that holey crucible ROCKS!

Eric


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## Lou (Apr 24, 2014)

Nice work, if you want spherical casting grain, use highly agitated, cold water. Alternatively, you can make nice shot by putting a wood board or piece of graphite and pouring onto that.


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## samuel-a (Apr 24, 2014)

Thank you guys for the kind words.

Butcher - The camera i used for the underwater shot is GoPro, it is an "extreme" camera as they call it and it has a casing that is designed to be water and shock proof.

Göran - Thanks for the embedding tip!

GotTheBug and Irons - Yes, i totally agree. The blanket is indeed more susceptible to degrade by flux fumes. There are "spay on" refractory clay/cement and also silicate based nano-suspensions to rigidize and protect it. I hear a good rigidizer makes it hard as a brick, you position the blanket in any shape you need and after the first heating run it sets, however i never tried it.

Lou - Thanks, i actually am using a water pump inside the bucket to circulate the water around, but i couldn't get a clear shot while the water was spinning around. I have seen it done similarly in Umicore, where they had a huge water tank and the water was swirling like crazy. the tank sits under the vertical "tapping" hole which is basically a multple holes grphite die, about 10-15 holes.



Lou said:


> Alternatively, you can make nice shot by putting a wood board or piece of graphite and pouring onto that.


I think i have an idea, but could you elaborate more? how should it work? 

Anyways, the silver/gold shot are later screend for re-cast small and large rejects, Here below is a screening kit i'm using:


For size reference, each tile on the floor is 1ft long


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## Lou (Apr 24, 2014)

What do you do with oversize, remelt it?


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## glondor (Apr 24, 2014)

Hey Sam, Very nice video! Brilliant idea for a low cost furnace as well. Well done!


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## samuel-a (Apr 24, 2014)

Lou said:


> What do you do with oversize, remelt it?



Re-melt only the really big and deformed. 
The oversized (>4mm) are very popular in electroforming as they love to use baskets instead of anodes.
Smaller then 850 micron goes back to melt as it tends slip through the bags.


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## justme2 (Apr 24, 2014)

Priceless. Thank smuch.


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## Lou (Apr 25, 2014)

Be careful in melting the silver too much--it will be useless for making bullion bars because of the oxygen. Your size distribution is odd--typically mine are no smaller than 2 mm and no bigger than 5 mm. Shovels nicely.

I melt silver with induction usually when shotting with an argon cover, but I greatly prefer gas furnaces (for silver, at least) for the reason of atmosphere control. A slightly rich flame does wonders for cast bars. There are other things to remediate silver instead of refining. A gram of lithium per 1000 oz is rather effective, causing a quick boil as dissolved oxygen reacts with the lithium that dissolves in the silver. 

Also, I suggest you look into some ITC-100 for the kaowool...will greatly extend its lifespan.
Another trick for that little bit of oxide smut in the video: a pinch of sodium carbonate and a small piece of pyrex glass. Clings all the oxides away and sticks to the crucible. If it's really heavy in slag/using old crucible, a stainless rod can be used to roll up a ball of flux glass--just be careful not to get it on you (far worse thermal burns due to the viscosity!).


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## samuel-a (Apr 25, 2014)

Thank you for the tips Lou.

Here's the PSD i took from the last silver pour:
0.41% <0.85mm (reject)
3.3% 0.85-2.38mm
38.45% 2.38-4mm
57.84% >4mm

It also has a lot to do with the pouring holes size. Originally i used 3mm diameter holes (with swirling of water) which produced smaller grains and tighter PSD.
But demand from clients was for bigger grains so i'm now pouring through 4mm pouring holes.

For gold i'm still using 3mm pouring holes.


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## Lou (Apr 27, 2014)

Glad to help! I like the educational aspect of your vids. I'm next door to Israel this week. Shame I won't have time to visit Israel this trip, I have some friends/customers I could have seen..

Seems like the polydispersity index isn't too bad. Normally, I just put the tundish on the top of the furnace exhaust and heat it until it glows.


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## samuel-a (Apr 28, 2014)

Dear Lou,

Have a productive trip.
I'd be very happy to meet up you next time your are in the area. In case you do get the chance to visit here this trip, you are more than welcomed.


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## philddreamer (May 16, 2014)

Hi Sam!
I just finished a prototype for incinerating black chips. It worked! 8)

I used 1 inch x 3 inch x 18 inches kawool bricks.

After pre-heating the furnace for about 15 minutes, I tested several types of chips; square black ones burned within 5 seconds. Same as the long IC. A BGA, same. The green fiber from a pin less P4 was the worst! About 10 seconds and some smoke. 

Thanks for sharing!

Phil


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## butcher (May 16, 2014)

Fire bug :lol:, I think you like watching things burn.


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## philddreamer (May 16, 2014)

Can't help it!!! :mrgreen:


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## philddreamer (May 20, 2014)

Butcher, I switched to the torch you gave me, and it works like a champ! Thanks! 8) 

I incinerated 1 pound - 9 0z. of BGA's black epoxy 3 days ago. The following day, I melted 20 T oz. of sterling. It took about 20 minutes to melt at low setting.

Today I melted 1 pound of mixed '70's & '80's pins at a medium setting! I'm planning on running the bar I poured thru a copper cell...
Next will be to melt the copper recovered from the waste batches. 

This furnace is a prototype, I'll set a nice level concrete base and put a much better one on it.

Thank you GRF! 8) 

Phil


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## necromancer (May 20, 2014)

Sam, where did you get the screening kit ?

do you have a link ?

thank you


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## butcher (May 21, 2014)

philddreamer,
Thanks for posting these pictures, this is very interesting (like looking through a good picture book).
I cannot wait to see more.


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## 924T (Aug 6, 2014)

phildreamer,

What kind of torch did you start out with,

and what kind of torch did Butcher send you?

I had bought a blacksmith forge torch, and it must have been a good one, because I loaned it
to a friend of mine 10 months ago, and haven't seen it since, which just killed the incineration
experiments I wanted to run.

So, I've got to come up with another torch, and it looks like whatever torch you're running
really gets the job done; thus my interest.

Cheers,

Mike


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## philddreamer (Aug 6, 2014)

I started out with a Mapp torch for pre-heating and a small oxy-acet torch for finishing the melt in my old little "furnace" made of woodstove bricks.

When I put together the Kaowool bricks furnace, I used the torch I got from Butcher. 
I did a melt 2 days ago and I ckecked the temp; it was 2,000F! This is using only propane. I'm happy with it! 8) 

Phil


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## butcher (Aug 7, 2014)

Back yard metal casting and forging is a good site to learn how to make some types of small furnace burners, or and learn how to make some types of furnaces.

http://www.backyardmetalcasting.com/

Normally for gold or silver a good torch and a melting dish is a about all you need, with some of the better small torches you may need to help contain the heat from the torch with Kwool or soft fire brick refractory.

The gold refining forum is a great resource of information on types of torch and dish which will work to melt gold, the different types of fire brick or refractory material which can be used, and different setups of furnaces, and what can work and what does not work.

I really like seeing that picture of Philddreamers glowing red furnace. Like the younger generation might say it looks so hot it is cool.


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