[TheForge] Making a Charcoal Kiln

[Jerry Frost]

Jeff:

Any wood will do though the less resinous the better, also the fewer mineral
solids in the wood the better. The amount of mineral solids determines how
much ash is left over after it's burned. Locally we have cottonwood that
makes absolutely horrible firewood as it leaves almost as much ash in the
stove as wood you put in to start. We'd literally have to clean the stove
every time we stoked it. You can determine the mineral content simply be
seeing how much ash is left over after a fire.

Here's how I've made charcoal the couple times I've done it.

I use a drum with a clamp on lid, replacing the rubber gasket with the
gasket rope used in wood stove doors.

If using birch like I usually do split and peal it as the bark is heavy with
creosote which is bad all round. Other woods may need different
pretreatment. In our neck of the woods (Alaska) the best I've found is the
local willow with alder being second, birch is third though in my
neighborhood birch is plentiful.

Anyway, pack the drum as tightly as possible with wood no thicker than 3-4"
in cross section. Clamp the lid on it and remove the bung.

Build a fire and place the drum on it, bung up. Keep the fire burning and
when the drum stops smoking douse the fire and plug the bunghole with
something that will breath like fiberglass. If you make an airtight seal the
drum will collapse as it cools.

A fast if wasteful method is to build a big fire and shovel the charcoal out
as it forms, dousing in water. Charcoal will dry quickly so it's not a
problem.

What you're trying to do is drive off the volitiles and leave the carbon in
as pure a form as possible. Not only is combustion not necessary, it's not
desirable as it consumes the carbon in the reactor instead of your forge.
All that's required is heat, time and a little venting. Also, the 3-4" cross
section recommendation isn't a must, it just yields nice sized charcoal in
the least time. If you had a log that fit the drum like a piston in a
cylinder it would work fine, just take a lot more time.

This is also far from the most sophisticated way of generating charcoal.
It's not much of a step up to set up reactors in series, allowing combustion
in the first then using the smoke and wood alcohol generated as burner fuel
for the reactors down the line. If I can find the URLs there are sites
showing how they do this in third world countries.

Frosty
------------------------
If it ain't forged
it ain't real.
Wrought iron is.
The FrostWorks

----- Original Message -----
From: "Jeff Harding" <jharding@kconline.com>
To: <theforge@mailman.qth.net>
Sent: Thursday, February 07, 2002 11:17 AM
Subject: Re: [TheForge] Making a Charcoal Kiln


> Bruce;
>
>    Point well taken... do you know how deep they stacked the hardwood
> in the drum?  Or how high they bank the fire on the sides?  I assume
> they cross stack or pile the hardwood so as to leave room for gas
> movement and heat to reach all the wood.
>
>    Thanks
>
>    Jeff   ><>