What mass of iron can be obtained by aluminothermy from 1 kg of natural magnetite containing 7.2% of impurities?

1. Let’s write down the reaction equation:

3Fe3O4 + 8Al = 9Fe + 4Al2O3.

2. Find the amount of magnetite:

1 kg = 1000 g.

m (Fe3O4) = m (ores) * ω (Fe3O4) / 100% = 1000 * 7.2% / 100% = 72 g.

n (Fe3O4) = m (Fe3O4) / M (Fe3O4) = 72 g / 232 g / mol = 0.31 mol.

3. According to the reaction equation, we find the amount, and then the mass of iron:

n (Fe) = n (Fe3O4) * 3 = 0.31 mol * 3 = 0.93 mol.

m (Fe) = n (Fe) * M (Fe) = 0.93 mol * 56 g / mol = 52 g.

Answer: m (Fe) = 52 g.