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vincentmarche

Advice on how to keep Magnetite from blowing out of smelt furnace?

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Hi all,

Trying my hand at backyard tatara smelt.  I assisted a friend with his last week and a lot of the fine magnetite he purchased online simply blew out of the furnace.

Any recommendations on how to work around this?
I saw one post where a guy mixed the magnetite with fine charcoal powder and water and make "cakes" with them but there was no other detail.

Any thoughts?

Thanks,
Vincent M

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The height of the furnace was bout 4- or  4.5 feet high. The blower was a leaf blower.

I was thinking that if he turned off the blower for the charge, poured charcoal on top and turned the blow back on that might mitigate some of the problem?

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Too much air and you are NOT going to pull Oxygen from the ore.  Was it running at a reducing level based on the flames on top of the furnace?  We always stopped the air when feeding in our smelting runs; but we were running a short stack Scandinavian bloomery and using hand powered blast.

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Possibly. They are designed to move large volumes of air very quickly, so I wouldn't be surprised if it were.  (Speaking from my -- very brief! -- experience trying to use a leaf blower to power a forge.)

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Have you looked at what other folks have used to run their tatara? (and a comparison of size of furnace of course.)

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Charcoal uses much less air than one thinks and charcoal dust is very light indeed. First an organic binder such as wheat paste might keep the charcoal and magnetite together a bit longer. As to air blast most primitive smelters used either bellows, natural draught from a tall chimney or in some places the prevailing winds. See the relationship? Low air speed. 

 

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I believe most primitive smelting experiments base success on %of available iron in the ore vs weight of usable product where 50% is very good. 

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a sample analysis of the iron content of various iron ores

  • Magnetite (black magnetic iron ore) Fe3O4 72.4% Iron

  • Hematite (red iron oxide ore) Fe2O3 69.9% Iron

  • Goethite (brown ochre) FeO(OH) 62.9% Iron

  • Limonite (brown hematite) FeO(OH)·n(H2O) 55% Iron

  • Siderite (Iron(II) carbonate) FeCO3 48.2% Iron

  • Taconite (low-grade ore needs special processing to be usable) FeO 25% to 30% Iron

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1 hour ago, Charles R. Stevens said:

I believe most primitive smelting experiments base success on %of available iron in the ore vs weight of usable product where 50% is very good. 

Fair point, my next step is to make that determination, any advice would be very helpful

 

As it stands now I have about 35 lb bloom not sure of the quality of the metal yet.

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Google should tell you what are average % or elimental iron in madnitite or then a comparison of the weight of your compacted bloom - an estiment of the amount of slag should give you a ball park. 

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I would refine the bloom a bit---at least to the muck bar stage and weigh it and compare to the weight of ore used to produce it.  The fuel weight to muck bar would also be a good indicator.

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Mr. Stevens,

Suggested binding magnetite and charcoal  (I. e. or carbon powder),  with wheat paste.  and forming pellets.

That works well.

In the past I have resorted to using a viscous sugar-water solution as a binder. (wheat paste was not available).

Yehh,  I'm cheap  and did not, really, want to dispose of the carbon fines.*

The pellets, worked well as a forge fuel.

Just sayyin,

SLAG.

* my young son and I had a frolic mixing up the "mud".  The ex  insisted that we hose down before entering the house. (no sense of humor?)

Said son successfully grew up, and now makes "mud" pies with the grand children.

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34 minutes ago, SLAG said:

 

I actually used Corn meal and corn starch with a bit of ground charcoal, added a bit of water, mixed, let dry and crumbled it up to the consistency of the crumbles you would find on top of a Coffee Cake, smelted well, I'm going to post the pics of the smelt and bloom shortly.

 

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