demolishing old furnace
digging pit
grate bars
chimney tunnel
Door brick
Building chimney
2 m tall chimney
Making charcoal
Un burnt wood can be used in next batch
Useable charcoal (burns hotter than ordinary wood)
iron bacteria
making wood ash (lowers melting point of ore)
ore charcoal powder and wood ash mixed inot a cylinder
slag falls through grate
melted mass pulled out
cast iron prills
note rust forming
pit and chimney furnace