In this guide, Ill explain why you should do gold ores at blast furnace (with a cc and gauntlets) CCs I know: Free Furnace and Open Furnace ask if there is any1 hosting at that time.
I was dumb and I was doing blast furnace using addy ores, because they are very profitable, but not profitable enough to the point where it is worth doing over gold ores.
So in 4 hours, i would get 280k Smithing exp (70K/hr) with a coal bag and also 3.2M (800K/hr)
If I were to do 1 hour of blast furnace with gold ores and gauntlets, I would get 280k Smithing exp (280k/hr) and lose 540k. If I did zulrah in the other 3 hours I would get 6M (that's avg 20 kills/hr and 100k gp each kill, which you can do much better, I've heard about some people getting 30+kills/hr) So overall in those 4 hours I would get 280k Smithing exp and 5.46M.
Hope it helps