Gather 200 stones from rock nodes, 100 wood from trees, and make 50 low grade fuel using 150 animal fat plus 50 cloth from hunting. Combine these in the crafting menu for your furnace, then find a secure spot inside your base. Drop it down and stock the inventory with wood as fuel, add your ore, and always leave a slot open for charcoal production. Hit e to fire it up.

When it comes to actual smelting, metal ore turns to fragments while sulfur ore becomes pure sulfur, and you'll get charcoal as a bonus from the wood burning. Makes sense to run multiple furnaces at once if you've got the materials, since waiting around isnt very efficient. Just make sure you've got enough wood stocked up before you start, and keep an eye on your base security since other players love targeting active furnaces.

Good to know: something worth noting is that the whole process feeds into bigger goals like better equipment and explosive crafting, so getting your furnace game sorted early really pays off. Just remember to protect your setup properly, since losing a batch of processed materials can set you back quite a bit.