Primitive Technology: Brick and Charcoal Production

The thatched hut where bricks are made. A batch of 50 bricks are just dry enough to put into the kiln This is done in crisscrossing layers of 10 bricks The bricks are then covered in old broken tiles and pot sherds to keep the heat in With the floor space empty, another batch of bricks is prepared Clay is placed in a brick mold (made from fired clay itself) to form a 25 x 12.5 x 6.25 cm brick Every couple of bricks, the mold is wetted to help the clay slide out more easily Making fire with fire

sticks A fire is lit in the kiln The roof keeps the rain off the bricks being fired, the bricks drying on the floor and the fire wood The smoke diffuse through the thatch, helping to preserve it against rot We can see the bricks getting red hot through the gaps indicating a good firing The next day, the cool bricks are taken out The pile of bricks The next batch of bricks to be fired Here I changed the kiln design to have 3 firing ports instead of 2 Primary air flows in through the 3 lower ports

while wood is put through the 3 upper ports Bricks are taken out the next day and added to the pile Ash is taken out of the kiln to be used for cement at a later stage The ash is wetted to form a paste It is then formed into bricks for storage When needed, the ash bricks will be fired in the kiln to calcine them and then mixed with water and sand to form a mortar More clay for bricks is dug The clay is placed in a pit where it will be slaked ready for making bricks Water is added to the 25 pots

loads of clay Clay is put onto the floor to make bricks It takes about an hour to make 50 bricks The kiln is daubed with clay to keep in the heat during firing The bricks are turned to help them dry faster When the bricks are semi dry they can be put into the kiln (though it's better for them to be completely dry before firing) So a drying fire is lit the day before the actual firing takes place The moisture slowly escapes so that the bricks won't spall due to steam explosions in the proper fir

ing Stacking the kiln's upper ports with wood lighting the fire in the lower port The kiln is stoked for 2.5 to 3 hours Bricks are taken out the next day Again the ash is taken out to form calcium storage bricks It's easier to make a well in a pile of ash and wet it into a dough than it is to mix it in a pot Any left over ash is made into a ball for storage The growing pile of bricks In addition to bricks, the thatched hut will be used for charcoal production, a fuel used for smelting iron Soi

l is made into mud to form the charcoal kiln A 75 cm diameter mud cylinder is formed This is built up till it is 50 cm tall 8 air holes are then dug around the base at equal distances A fire is lit to dry the mud Dry, dead wood is collected and broken up to make charcoal The charcoal is stacked into the kiln in alternating layers Once the cylinder is full, a conical pile of wood is built on top Finished stack Coating conical top with mud A small hole is left in the top to start the fire in The f

ire burns back down through the hole in the top of the mound The wood slowly carbonizes to charcoal due to incomplete combustion When the fire front reaches an air entry, it is plugged with mud Each hole at the base is plugged when fire can be seen through it When the last air entry is plugged, the air exit at the top is plugged also The whole process takes about 3 hours The next day, the conical top is broken open Most of the wood has become charcoal A wicker sieve is used to grade the charcoal

. The finer coals fall through while the larger coals roll into the pot The charcoal is taken to the brick hut to be used for smelting 6.5 pots of charcoal were made in this firing A later batch made 9.5 pots of charcoal due to better stacking Charcoal being used for smelting iron ore Yet more bricks added to the pile About 250 bricks 9 ash bricks as a source of calcium for making mortar later Brick, mortar and charcoal production factory