An Ore Smelter initially spawns at your base adjacent to your CPH. You need the Build Gun v2 to remove it. It smelts at a rate of ~16 ore/min* requiring 3.3 PPS and can hold 128 EU. Ore smelters can be modified by placing a Forced Induction Module on top which increase the smelting speed.
*Due to the time it takes to load ore into the smelter, the actual smelting time is slightly less than 16 ore/min.
Warm Up Time Edit
The smelter has a minimum operating temperature, and will not begin smelting until this temperature is reached. If the smelter is idle, its temperature will fall relatively quickly and it will need to warm up again for several seconds until it begins working.
While warming up, the Smelter will require 3x as much power. This power cost is also multiplied again by Forced Induction modules. However, these only multiply current cost, so if the player is low on power they can add the module after the Smelter is already heated.
This typically is only important on Scarce power settings, where Forced Induction multiplies power cost by 8x instead of 2x.
If used below -30m you'll see this message when mousing over the smelter or inductor; "smelter starved of oxygen!". The smelter will operate at a drastically slower rate when deep enough underground.