\(m_{Fe_2O_3}=12000.85\%=10200(kg)\\ \Rightarrow n_{Fe_2O_3}=\dfrac{10200}{160}=63,75(kmol)\\ \Rightarrow n_{Fe_2O_3(p/ứ)}=63,75.80\%=51(kmol)\\ \Rightarrow n_{Fe}=2n_{Fe_2O_3}=102(kmol)\\ \Rightarrow m_{Fe}=102.56=5712(kg)\\ \Rightarrow m_{gang}=\dfrac{5712}{96\%}=5950(kg)=5,95(tấn)\)