Arc Smelter

The Arc Smelter is a building that smelts certain materials into other materials by applying high heat. It is used primarily to turn ores into their corresponding ingots, but it is also required for producing magnets and certain intermediate materials such as crystal silicon and diamond. As an electric arc furnace, it consumes electricity to operate and does not need fuel.

Its basic use is in the early and mid game, when ore processing becomes a bottleneck and almost every production chain depends on smelting. The Arc Smelter is one of the most commonly deployed buildings in the game, so it is worth automating its production early rather than hand-crafting replacements whenever a new factory block is built.

Typical recipes handled by the Arc Smelter include:

• Copper Ore → Copper Ingot
• Iron Ore → Iron Ingot
• Stone → Stone Brick
• Stone → Glass
• Coal → Energetic Graphite
• Titanium Ore → Titanium Ingot
• Silicon Ore → High-Purity Silicon
• Iron Ingot → Steel
• Iron Ore + Sulfuric Acid + Titanium Ingot + Steel → Magnets
• High-Purity Silicon + Energetic Graphite + Kimberlite Ore → Crystal Silicon
• Crystal Silicon / Diamond-related processing for diamond production

The Arc Smelter’s throughput scales with conveyor tier. A single row of smelters can fully saturate the following belt capacities:

• Conveyor Belt Mk.I: 6 Arc Smelters at 360 items/min
• Conveyor Belt Mk.II: 12 Arc Smelters at 720 items/min
• Conveyor Belt Mk.III: 30 Arc Smelters at 1800 items/min

For the magnet recipe, the corresponding numbers are lower because the recipe is slower: 9, 18, and 45 smelters per Mk.I, Mk.II, and Mk.III belt respectively. For the crystal silicon and diamond chain, the requirements are 12, 24, and 60 smelters per belt.

When planning mining outposts, it is easy to underestimate how many Arc Smelters are needed. Bringing a substantial stock along with the materials to craft more on-site is standard practice, especially Stone Bricks, since expanding smelting capacity is often necessary as soon as a deposit is tapped.