Primitive Technology: 2.5 m Natural draft furnace experiment

2.5 m Natural draft furnace experiment Subscribe: http://bit.ly/subPT | Never miss a video! Enable ‘ALL’ Notifications! Watch my newest content:    • Newest Uploads | Primitive Technology   Follow Primitive Technology: Wordpress: https://primitivetechnology.wordpress... Patreon: https://patreon.com/user?u=2945881 Watch More Primitive Technology: Newest Uploads:    • Newest Uploads | Primitive Technology   Pyrotechnology:    • Pyrotechnology | Primitive Technology   Shelter:    • Shelter | Primitive Technology   Weapons:    • Weapons | Primitive Technology   Popular Videos:    • Popular Videos | Primitive Technology   About This Video: I built a 2.5 m tall furnace to see if it could get hot enough to smelt iron by natural draft alone. Such furnaces work by the stack effect where the tall furnace causes negative pressure inducing an air flow from the base of the furnace and out the top. I'd previously built 2 natural draft furnaces 1.5 m tall with one producing a small amount of iron (4 grams) from ore. The new furnace was built 25 cm in diameter and 50 cm tall with a chimney on top extending another 1.5 m. A charging door allowed charcoal and ore to be charged through the side without blocking the chimney. The furnace was hot enough to produce slag but no iron was recovered from the smelt. This was probably due to an oxidising atmosphere in the furnace, due to the short fuel bed and large charcoal lump size. An interesting side effect of the test was a strange pulsing combustion when the door was left open. Flames and smoke would blow out and be sucked back in the charging door rhythmically so it sounded like a locomotive. This phenomenon has been observed in wood stoves, I don't think it's exactly like combustion in a pulse jet as it relies on natural draft to get started but is similar. Air is sucked in, the gases combust blowing air out the door and chimney, the gases in the furnace become over expanded causing a vacuum and air is sucked back in with the cycle repeating. In future it may be necessary to mix carbon with the ore to form pellets to get it to convert to iron. I'd made a furnace like this bottle shaped design back in 2012 but with a grate rather than using tuyeres and it successfully made some nuggets of iron from an ore brick of ore and crushed charcoal set directly on the grate. About Primitive Technology: Primitive technology is a hobby where you build things in the wild completely from scratch using no modern tools or materials. These are the strict rules: If you want a fire, use a fire stick - An axe, pick up a stone and shape it - A hut, build one from trees, mud, rocks etc. The challenge is seeing how far you can go without utilizing modern technology. I do not live in the wild, but enjoy building shelter, tools, and more, only utilizing natural materials. To find specific videos, visit my playlist tab for building videos focused on pyrotechnology, shelter, weapons, food & agriculture, tools & machines, and weaving & fiber. #PrimitiveTechnology #1 #2