The orange slime is a type of bacteria that precipitates iron oxide dissolved in ground water
Collecting the iron bacteria
Pouring iron bacteria into a porous clay pot
Over time the water seeps out. Clear water on top is bailed out.
Taking out concentrated ore to leach in another smaller pot
Iron bacteria congealing
Drying iron bacteria near fire to be used as iron ore later
Iron ore balls drying for storage
Crushing the ore into powder closer to smelting time
Powdered ore allows the heat and carbon monoxide to penetrate the smaller particles more effectively
Ore ready for smelting
Making charcoal in a pit, stacking the wood over top
Making alternating layers of firewood
Leaning wood against pile to stop horizonal logs rolling off
Light from the top with hot coals
Fire front burns down the pile against the flow of rising gasses, carbonizing the wood to charcoal without burning it
The coals fall into the pit when the first layer burns and collapses
Un-burnt logs are lifted to the top with a stick to carbonize more fully in the air
When they break apart and no longer give off flames the coals are extinguished with water
Allowing the residual heat to evaporate excess water
This method is simple and quick, while the resultant charcoal is non-dusty (good for lungs) and is of sufficient quality for smelting.
Making the tuyere for the furnace from clay molded over a log
Narrowing tuyere with a thinner stick
Making bricks from ordinary mud in a ceramic brick mold
Drying and turning bricks
Placing tuyere at the front of a small pit about 12.5 cm deep and putting bricks on their sides around to form a furnace. The front is left open with a half brick
Plastering front of furnace with mud. The nose of the tuyere penetrates about 2.5 cm into the furnace
The next layer of bricks is staggered over the joints of those below for stability
3 layers in total
Plastering gaps between bricks with mud to stop the gases coming out the sides instead of up through the ore
37.5 cm tall and about an 18.5 cm square inner cross section
The centrifugal blower for the furnace
Pre-heating furnace for smelt (1 hour burning wood)
Filling the furnace with charcoal (12 double handfuls of charcoal)
Adding the first charge of ore (2 single handfuls of iron bacteria)
Powering the blower for about 5-7 minutes
Carbon monoxide starts to burn above the furnace in a violet tinged flame, a sign of the reducing atmosphere inside the fuel bed (good for reducing ore to metal)
2nd charge: 3 double handfuls charcoal/2 single handfuls ore
Another 5-7 minutes blower
3rd charge: 3 double handfuls charcoal/2 single handfuls ore
4th charge: 3 double handfuls charcoal/2 single handfuls ore
5th charge: 3 double handfuls charcoal/2 single handfuls ore
6th and final charge: 3 double handfuls charcoal/2 single handfuls ore
Kept blowing for about half an hour afterwards to burn down to tuyere level
Extinguishing furnace to get result out
Note, the brick furnace is easy to disassemble to access the product
Mass of slag and iron prills attached to the brick wall directly under the tuyere nose
Dislodging slag and iron
Some decent sized prills, though not as good as previous smelts though due to a seasonal change in the iron bacteria quality (more mud this time)
Getting the large prills out first
Crushing the slag to get more out
Using a crude panning technique with a pot to get out the small pieces (on the advice of viewers of this channel)
Resultant iron yield (about 15 g)
Trying a larger tuyere (5cm as opposed to 2.5 cm)
Again, building a furnace from bricks makes it quick, easy, portable and re-useable.
The same smelting process with the larger tuyere
It's about the same yeild of iron (15 g) but smaller pieces
Trying a circular brick furnace. Furnace is the same height but has a diameter about 22 cm (larger cross-sectional area)
Bricks are stacked on their ends and joints sealed vertically.
The same smelt again, 5 cm diameter tuyere but circular furnace
Again some ok sized prills about the same yield. I'll probably stick to the square furnace as it's the easiest to build and gives the same result
Adding up all the iron from various smelts into one pot