Studies on metal flow from khondalite to bauxite to alumina and rejects from an alumina refinery, India

Abstract

Alumina is produced from khondalite hosted bauxite of Indian origin in the Alumina refinery employing the time tested Bayer’s Process. In the process, about 40% of unwanted elements are rejected as undigested sand and red mud. During the whole cycle major, minor, trace and RE elements in these litho-units get redistributed, either depleted or enriched. Khondalite, the source rock of bauxite, is rich in silica, moderate in alumina and iron with minor titanium. Bauxite becomes rich in alumina and iron with subordinate titanium and negligible silica. After alumina recovery from bauxite, most of the valuable metals including REE get accumulated in the refinery rejects. The studies, while establishing the extent of various metals dispersed in khondalite, bauxite, undigested sand, red mud and alumina also reveals the state of enrichment of valuable metals in undigested sand and suggests possible means to recover some of them.