This is correct, and the carbon is a byproduct. The reason is to get rid of the oxide in the iron-oxide compound. The way I understand it, is that when mined t

This is correct, and the carbon is a byproduct. The reason is to get rid of the oxide in the iron-oxide compound. The way I understand it, is that when mined they get iron-oxide, Fe(2)O(3), or Fe(3)O(4), so there is no carbon present. They use the coke to make carbon monoxide (CO). And this process removes the oxide and adds carbon to iron to create pig iron. From there it will be further processed to create different steels, alloys and iron products. Wikipedia (https://en.wikipedia.org/wiki/Iron_ore https://en.wikipedia.org/wiki/Iron_ore) under the smelting paragraph describes the oxide removal process.