Companhia Brasileira de Alumínio (CBA) has a preparation plant at Itamarati de Minas, MG. This plant washes two different kinds of bauxite ore, one originating from the laterization of gnaisses and another from amphybolites. Both ores have the same behavior in the coarser size fractions but behave differently under 0.355 mm (42# Tyler). In these small sizes, gneissic ores are rich in quartz and amphybolitic ores are rich in iron and titanium bearing ores. The unit operations are: scrubbing of the feed in drum scrubbers, desliming in cyclones, and screening of the scrubbed bauxite in high frequency screens (0.355 mm) - the +0.355 mm product is a final concentrate. The -0.355 mm fraction is desliming in two stage cyclones and goes to a fines gravity concentration circuit of Reichert spirals complemented by magnetic separation of the light product from the spirals. The research work, including mineralogy, process development, batch tests and pilot plant tests, is described and compared to the actual results in the industrial circuit.
Bauxite preparation; gravity concentration; Reichert spirals
