Question

Describe briefly the Goldschmidt aluminothermic process.

Answer 1

The Goldschmidt aluminothermic process, which uses aluminium powder to reduce roasted ore, is used to reduce metal oxides that have extremely high melting temperatures and are difficult for carbon to reduce. These oxides include metals such as Cr₂O3, Mn₃O₄, etc. These are combined with powdered aluminium and placed in a fire clay crucible that is submerged in sand. An ignition mixture including BaO₂ and magnesium powder is used to initiate the reaction.

\[\ce{Cr2O3 + 2Al -> Al2O3 + 2Cr}\]

\[\ce{3Mn3O4 + 8Al -> 4Al2O3 + 9Mn}\]

Both the metal and the alumina fuse as a result of these highly exothermic processes that generate a significant quantity of heat. Because it is heavier, the metal collects at the bottom of the crucible where the reaction takes place.