>>11788821Pretty much everything except iron is a lot uglier to refine from oxides. Simply heating and blowing a reduction agent doesn't work, you usually need to do electrolysis. Aluminum smelting requires running electricity across some carbon electrodes at very high voltage and amperage, simultaneously breaking the aluminum-oxygen bonds and evaporating some carbon, which reacts to form carbon oxides.
So to make aluminum, titanium, silicon etc, you're paying the energy bill twice; once to make your carbon reducing agent, and again to electrolyse the metal oxide you're refining. It isn't exactly trivial to make a carbon electrode starting off with carbon dioxide gas, either.
Oh, and hydrogen doesn't really work for the application of reducing electrolyzed metal oxides, because metals that bond to oxygen that tightly will actually tell any hydrogen bonded to oxygen to fuck off and steal that oxygen for themselves. This is why you don't try to extinguish a magnesium or titanium fire using water; you would effectively be adding an oxidizer that also vomits a bunch of hydrogen gas as it accelerates the burn rate of the metal.
