(80/100) * 220 kg = 4 * 220 / 5 = 176 kg hematit pur
176 kg mt
--------- --------
2 Fe₂O₃ → 4 Fe + 3 O₂
--------- --------
320 kg 224 kg
mt = 176 * 224 / 320 = 123,2 kg Fe (masa teoretica)
randament = masa practica * 100 / masa teoretica
randament = 72,8 * 100 / 123,2
randament = 59%