\(m_{FeS_2}=45-45.20:100=36kg\\ FeS_2\rightarrow H_2SO_4\\ \Rightarrow2n_{FeS_2}=n_{H_2SO_4\left(lt\right)}\\ \Rightarrow2\cdot\dfrac{36}{120}=\dfrac{m_{H_2SO_4\left(lt\right)}}{98}\\ \Rightarrow m_{H_2SO_4\left(lt\right)}=58,8kg\\ m_{H_2SO_4\left(tt\right)}=58,8.60:100=35,28kg\\ m_{H_2SO_4,70\%}=35,28.100:70=50,4kg\)