Removal of limestone from
bauxite by magnetic separation
E.Th. Stamboliadis*, G. Kailis
Mineral Resources Engineering Department,
Technical University of Crete, 73100 Chania, Greece
Received 13 November 2002; accepted 15 November 2003
Bauxite is the main source for the production of alumina and metal aluminum
by the Bayer process. Limestone is an impurity associated to bauxite due to
geological and morphological conditions prevailing during its formation.
Experimental work has shown that limestone can be easily removed from
bauxite using magnetic separation techniques.
Three samples of Greek bauxite were used with different CaCO3 content, that
assayed between 2.5% and 8.5% CaO. The samples were screened to three size
fractions 0-5mm, 5-10mm and 10-20mm. The equipment used for the test work
was a belt roll magnetic separator and it was possible to produce more than
one magnetic products from each fraction by passing the non-magnetics for
second or third time. From one pass to the other the roll speed and hence
the feed rate was reduced. The results show that limestone can be removed
from bauxite. Depending on the feed CaO assay and the specifications of the
product it is possible to produce different product qualities leaving the
non magnetic fraction as a residue.
Keywords: Limestone; Bauxite; Magnetic separation
* Corresponding author