\(0,58\left(tấn\right)=580000\left(g\right)\\ \Rightarrow m_{Fe_3O_4}=580000\cdot80\%=464000\left(g\right)\\ \Rightarrow n_{Fe_3O_4}=\dfrac{464000}{232}=2000\left(mol\right)\\ PTHH:Fe_3O_4+4H_2\rightarrow3Fe+4H_2O\\ \Rightarrow n_{Fe}=3n_{Fe_3O_4}=8000\left(mol\right)\\ \Rightarrow m_{Fe}=8000\cdot56=336000\left(g\right)=0,336\left(tấn\right)\)