Making coke
Heat fuel in a sealed retort to make coke.
You make a retort from blocks. There is no retort item or crafting recipe; the tooltip on Fuel is the in-game hint. Heat sealed fuel to 115 °C and it turns into Coke and Coke Gas.
Coke makes a Coke Ember at 215 °C. That is hot enough to smelt tungsten, which needs 211 °C. You can smelt titanium with an ordinary fuel fire.
You will need
- Fuel, made by letting Coal touch Steam
- Stone or Iron for the inner wall
- Wood and the Flint Striker for a fire outside the wall
- Optional Gas Sieve cells for a larger batch. A bench makes four from 2 Copper and 1 Glass
The Flint Striker reaches only 110 °C, below the 115 °C needed to make coke. Wood Ember reaches 130 °C. Exposed fuel ignites at 135 °C, so keep flame and embers out of the retort.
Build and heat it
- Make a stone box with walls one cell thick and a 3-by-3 space inside.
- Fill all nine interior cells with fuel and close the roof. Fuel is a liquid. Leave no gaps for it to leak through or for air to touch it.
- Put wood outside the stone wall and light it. Keep at least one stone cell between every ember and the fuel. A two-cell-thick ring of wood, contained by an outer stone wall, works for a first batch. An iron inner wall and coal fire also work, but get hotter than you need.
- Let the fire heat the fuel to 115 °C. Each pair of hot fuel cells turns into one coke cell and one coke gas cell. A small sealed batch works without a vent. For a larger batch, put Gas Sieve cells in the wall so gas can escape. Keep the outlets away from the fire.
- Wait for the fire to burn out before opening the box.
A fuel cell converts only when it has no empty air or flame next to it and is at least 115 °C. Adjacent hot fuel cells convert quickly. If the box stays full of fuel, check that heat is reaching the inside and that the fuel is sealed. A thick wall or a poorly conducting material can leave the fuel cold.
Use stone or iron for the inner wall. Stone conducts heat at 85 of 255 and iron at 255. Refract conducts at only 4, and Ceramic at 18. Refractory lining is useful when you want to keep heat out, but it makes a poor retort wall. A Heat Lamp will not work either: it stops at 100 °C.
If the fuel catches fire, check for a gap or an ember touching it. Sealed fuel cannot ignite, but exposed fuel ignites at 135 °C. If you open a hot retort and the coke becomes coke embers, let it cool longer next time. Coke ignites at 150 °C, below a coal ember's 185 °C but above a wood ember's 130 °C.
Coke gas takes up space in a sealed batch. Gas Sieve cells can improve the yield of a larger batch, but send the gas somewhere safe. Coke gas ignites at 145 °C.
Going down covers the layers where you can find titanium and tungsten.