DIY assay furnace

[Bonaro]

I am on the injured reserve list so I am catching up on all the little projects I have wanted to do but haven't had the time.
I saw a video about a soup can blast furnace on you tube so I decided to make a small assay furnace.
The pics are pretty self explanatory if you look at them. It aint pretty bit it works and I only have about 2 hours invested in it and had all the materials laying about.

Furnace sldeshow

 

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[KevinInColorado]

Great photos and I think it looks really good! Can you add some commentary on materials used, what you learned along the way, tips for others, etc?

 

[russau]

affordable . practical , and small enough to put anywhere you want! nice project Dan!

 

[mike(swWash)]

Will a propane torch get it hot enough to melt the material in the crucible?

 

[roadrunner]

Yes propane will.
Go look at youtube.
I bought mine from canvasman34. And I do not make anything by saying this.
Just a great small furnace and he includes crucibles, and molds.
Of course free is way better, and building it yourself.

 

[Bonaro]

Test fired today. From a warm start I was able to melt aluminum in about 3 minutes and brass in about 5 using only propane.
I plan to test it using propane/oxygen maybe tomorrow to see if I can melt steel.
The Flooring thin set I used for mortar is already starting to give up. I need to start over with ceramic clay or plaster of paris

Kevin, details about my build are in tiny hard to read captions at the top of the slideshow

 

[Jimmydolittle]

Here is some more info on building a furnace: http://www.backyardmetalcasting.com/book_fp.html

 

[Duckwalk]

i suggest building a Brake Drum forge. I used to do blacksmithing and did all sorts of trade shows between the ages of 15 and 19. Brake Drum forge will get well above 3,000 degrees and is super cheap. It was the first forge i ever had and is still working to this day. Here is an example video of a brake drum forge. You can even use woodchips instead of coal. around here they are free and abundant.

This is just a quick example of what im talking about. one properly built with the correct airflow will heat much faster than the one posted.

 

[KevinInColorado]

For running actual assay samples you will need to be able to manage oxygen exposure of the assay sample so you can drive the reduction and oxidation reactions correctly. An open heat source will not do the trick for reduction, that needs to be done in an oxygen poor environment such as an enclosed furnace.

 

[Duckwalk]

Class is now over lol

 

[Marmentman]

Good point Kevin. Some material like silver can be explosive with acetylene. So if you use a torch other than propane, know what your doing. I see how a controlled low to no oxygen forge would be easier to control oxidation, but how do you control this when oxygen is one of the requirements of fire?

 

[Duckwalk]

in a forge, all oxygen is coming from underneath, once burned off, its no longer O. A forge can run completely top covered as long as airflow is being provided underneath the fire pot.

 

[ConceptualizedNetherlandr]

Good point Kevin. Some material like silver can be explosive with acetylene. So if you use a torch other than propane, know what your doing. I see how a controlled low to no oxygen forge would be easier to control oxidation, but how do you control this when oxygen is one of the requirements of fire?

Maybe an electrical heat source, or heat the outside of the sealed (but pressure vented) chamber.

 

[ConceptualizedNetherlandr]

The one thing about the unit built here that bothers me is the horizontal propane tank. They seem to clog tips real bad because of the non-propane liquid components that soot things up if non vapors come through the valve.

A flexible line from the tank, or some stand for the unit where the inlet is at the torch tip angle perhaps.

 

[KevinInColorado]

Maybe an electrical heat source, or heat the outside of the sealed (but pressure vented) chamber.

Right! Even just "mostly" sealed is good enough for reduction. One way or another, use of lead litharge for fire assay requires a reduction reaction. I've done it, it's fun!

 

[Bonaro]

I was using the hand torch only to test the design.
I have a mega minor surface mix torch that I will use in my final build

I also have a medical oxygen concentrator that I will use to supply constant o2

If I need to reduce the ambient o2 but need more heat I will just use MAPP gas.

The forge is cool but not nearly as compact and portable as the kiln. Probably more suited for metal work than assay

 

[roadrunner]

Go look at youtube.
If I remember right, use a 50/50 mix of mortar and kitty litter.
Make sure to pack it and make sure it is totally dry before firing.
Do this by firing after its dry with a little heat, or put it in a oven.
Or part vermiculite. Or the mica we used to use in grill bottoms.

 

[Bonaro]

Vermiculite is a good idea. It would be lightweight but maybe not very strong.Plain old terra cotta type clay would probably work