PROCESS OF BAUXITE AND RED MUD WITH DISSOLVING BY CRIOLITE

摘要

Aluminum is dissolved from calcined and pretreated bauxite and red-mud. Bauxite is ground to suitable size and calcined over 800 [deg] C. As a result all water of crystallisation is lost from the mineral, the majority of iron-oxide present is converted to magnetisable hematite form and Al2O3 assumes corundum form. Accompanying metals are removed by magnetic action, flotation etc., during pretreatment. The whole Al2O3 content being in corundum form is available for electrolytic processing. Resulting Al is refined by known means following removal of all possible contaminants. Processing of red-mud is the same as for bauxite with the exception, that following calcination, a sodium-hydroxide wash-out constitutes the first step.