Primitive Technology: Iron knife made from bacteria

By | October 31, 2022

Creek with iron bacteria in the water (orange/yellow slime). The iron bacteria derive their energy by oxidizing iron dissolved in the water. Collecting the dilute iron oxide precipitate Pouring iron precipitate into porous clay pot The water leaks out while iron oxide remains inside the pot Iron oxide ”mud” is then taken from the pot to dry Dried iron oxide, the ore that will be used Stacking wood into a pit for charcoal The pile is lit from the top and allowed to burn down, carbonizing the pile Un-burnt brands are raked to the top to carbonize more completely When the coals have visually carbonized (turned black), they are extinguished with just enough water to do so The charcoal is then taken out and stored when cool enough to handle This method of making charcoal is quick, simple and effective Making a furnace pit (12.5 cm deep, 25 cm wide) lined with clay Tuyere (air pipe) is 12.5 cm from bottom of pit and penetrates 2.5 cm in from inner wall The furnace then extends 37.5 cm above this (50cm from bottom to top) The improved multi blade impeller from last episode Pre-heating the furnace with wood for one hour Filling the furnace with charcoal Adding the first charge of ore (2 single handfuls or 200 grams) After 300 pulls of the string (5 minutes) 3 double handfuls of charcoal (500 g) and 2 single handfuls of ore (200g) are added Again, 5 minutes, 500g charcoal, 200g ore. This was done 6 times over 30 minutes After the last charge, the furnace was fired for another 30 minutes until the charcoal burnt down to the level of air entry The material in the furnace was then removed and inspected The result was slag with iron prills through it There were also larger iron prills in the coals that had dripped out of the slag. Breaking up the slag yielded more iron nuggets From 1.2kg of ore 40 g of iron was produced in 2 hours I then did another smelt that went almost exactly the same A stone mortar helps with breaking up the slag and retrieving the iron Approximately another 40 g of iron 80 grams iron in total for about 4 hours smelting Making a mold to cast the iron into

It's made of clay and is a triangle shape about 10cm long and 3cm wide at the base The prills are placed into the mold and will be melted in situ rather than being poured from a crucible A special tuyere had to be made with a wide, flat mouth to blow a sheet of air over the entire width of the mold A simple open hearth with the flat nosed tuyere is made The mold with the iron in it is placed in the hearth, just in front of the flat nosed tuyere Hot coals and charcoal are placed on top of the mold Then the forced draft is applied The iron prills I made are actually cast iron, due to the high carbon to ore ratio used in the smelt Cast iron has a lower melting point (1150 C) than pure iron (1538 C) Because of this relatively low melting point, the iron can be melted in a simple open hearth This process took about 15 minutes at most Retrieving the mold Success I was going to make an axe but decided it would be too brittle, so I sharpened it into a knife Each transition here is about an hour of sharpening Though cast iron is more brittle than pure iron, it is much harder, so it takes a lot longer to sharpen. 10 hours sharpening in total Though the cutting edge is a bit blunt, the point is well suited for drilling holes in wood and carving notches (like for fire sticks) Iron knife made from bacteria

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