Blast Furnace

The blast furnace is a large multiblock furnace used for mass-smelting iron in the midgame.

Use/Progression
The blast furnace is essential for smelting large amounts of iron, and it requires fuel, flux, ore, and carbon (coal). It is slower than a regular furnace, but can be sped up with improved fuel sources. It can't smelt any other metals copper, tin, gold, or silver, but it is required in the refining of ignotumite and mithril. Unlike the bloomery, it produces full ingots at a 1:1 ratio of ores to ingots instead of 1:2.

Construction
Required Iron: 17 (1s + 38 ore)

The blast furnace is made of a 3x3x2 stone brick base with a lava source in the middle of the upper layer, an output block in front of the upper layer of the stone brick base, a heater above the lava source, 4 furnace shafts above that, followed by an input block and 2 more shafts, with everything above the base being surrounded in a stone-based material (except for the front side of the heater and input). MAKE SURE THERE ARE NO BLOCKS ABOVE THE SHAFT EXCEPT FOR CHIMNEYS.