Impact assessment of waste screening over the life of a Brazilian bauxite mining operation

Bauxite at a mine in Pocos de Caldas, Brazil, is mined using the bench method, followed by grinding and chemical treatment using the Bayer process. Studies have been carried out of the financial and technical feasibilities of using a flip screen loader bucket to recover ore from the overburden at the mine. The flip screen was installed in the loader bucket to physically concentrate bauxite in the waste, increasing the content of the available alumina (AA), and reducing the reactive silica (RS) and organic carbon contents (OCC). Preliminary tests were successful in the oversize material (greater than 12.7 mm), giving an increase of 13% in AA and reductions of 22% in RS and 47% in OCC. The mass recovery averaged 48%. Some operational challenges regarding the flip screen need to be overcome, including adjusting the number of turns of the bucket and installing a brush kit to prevent screen clogging. Around 7 000 t of bauxite were produced in 4 months with an average product AA grade of 44% and 4.63% of RS. The produced mass was more than 75% of the value invested in the purchase and installation of the equipment.
Bauxite at a mine in Pocos de Caldas, Brazil, is mined using the bench method, followed by grinding and chemical treatment using the Bayer process. Studies have been carried out of the financial and technical feasibilities of using a flip screen loader bucket to recover ore from the overburden at the mine. The flip screen was installed in the loader bucket to physically concentrate bauxite in the waste, increasing the content of the available alumina (AA), and reducing the reactive silica (RS) and organic carbon contents (OCC). Preliminary tests were successful in the oversize material (greater than 12.7 mm), giving an increase of 13% in AA and reductions of 22% in RS and 47% in OCC. The mass recovery averaged 48%. Some operational challenges regarding the flip screen need to be overcome, including adjusting the number of turns of the bucket and installing a brush kit to prevent screen clogging. Around 7 000 t of bauxite were produced in 4 months with an average product AA grade of 44% and 4.63% of RS. The produced mass was more than 75% of the value invested in the purchase and installation of the equipment.