Monday, June 17, 2013

making charcoal

 I've been smelting aluminium, making ingots for future experiments in sand-casting. I found that the cost of barbecue charcoal problematic and my yard is full of twigs so I decided to make my own smelting fuel.

In researching the various methods I found that there are two primary methods for making charcoal, direct and indirect.

The direct method involves making a fire and smothering it to the point where it burns off the volatiles and contaminates. This method was very popular but I had problems with quality and if you screw up it can explode. As I like my hair,eyebrows, fingers and dangly bits I looked into the indirect method also known as the "retort" method.

  This method involves placing the material to be made into charcoal into a airflow restricted container and applying heat bringing the material above combustion temperature without allowing any combustion.

 I did this with various food cans. Notably soup. I made the retorts by placing a progresso soup can over a cambels can as an insert. Fill the cambels can with twigs cover with the progresso can and you have a retort with restricted airflow that also allows for pressure release of the pyrolytic gas around the bottom which then burns and adds energy to the process.

I also made a larger retort out of a coffee can and a paint can.

  For a furnace I used a bunch of old bricks, a small 12 volt muffin fan, a grill from a dead toaster oven and a random piece of metal cut from the back of an old computer case as a spark catcher. (the part with all the holes in it.)

The assembled furnace.

Showing the grill and rudimentary ducting.

 The muffin fan as an air mover.

Place the four smaller retorts on the grill.

Surround with wood. In this case some dried sagebrush, rose branches,and pieces of a dead apple tree.

Place the larger retort on top.

More wood.

Fill to the top. Add a firestarter based on this instructable

 Light it up!

Place the sparkcatcher on top, more bricks to hold it in place. Hook a 12 volt battery to the fan.

Lots of fire and whooshy noises. Now is the time to roast weenies and marshmallows, dance naked in obeisance to the fire gods, whatever.

Next morning. I save the ash for making wood lye.

Remove the retorts.
Look inside, discover the flaws inherent in trying to see a black substance inside a black container.

 I'd call it a successful proof of concept. I'll do this a couple of more times and then try smelting some soda cans into more ingots.

 cost of materials: 0
labour hours       : about 1
time for process  : approx 3 hours.
Yield                    : Variable based on density of feed stock. harder/denser  woods= better yield.