Latest refractory construction uses kiln bricks, dry stacked. More complex shape of the inlet and exhaust ducting is made from calcium aluminate castable cement with brick grog. 1:5.
As with earlier iterations of retort, 200L drums are used to to house the shape. The bricks forming the walls are chamfered so as to be self locking, each one wedging the others from falling in.
The firebox floor is dry stacked with brick grog chip to hold them in place.
Lower firebox structure, flame inlet will be to the right.
Recycled bricks marked H35 are believed to be high temperature kiln type. Note: diy chamfer.