Alright, forget the pretentious retort kiln. The cone kiln is simplicity itself. Just beautiful.
What one can achieve by slight change of degree.
And look at that water coming out at the end of the video. Just as clean as when it went in - cleaner probably.
Also, one can do the same method just by digging a cone pit in the ground.
One thing I did not know was that dousing the hot char with the water expands the porous structure - which is good.