GEOLOGY, MINING OPERATION AND SCHEDULING OF THE PARAGOMINAS BAUXITE MINE

Silva, H.M., Picanço, E., Maurity, C., Morais, W., Santos, H.C. and Guimarães, O.

The Paragominas bauxite mine (VALE) is the first in the world integrating the mine process with beneficiation and transport of milled bauxite by mineral pipeline. The mine is located in the far north of Brazil, in the State of Pará, part of the eastern Amazon region. As from 2001, Vale has undertaken exploration and technical characterization of Bauxite over the whole of the Paragominas Bauxite District, culminating in the opening of the first VALE mine an the Miltônia Plateau, based on reserves equivalent to 300 MT of beneficiated product.

The geological profile of the deposits consists of seven layers: Topsoil and Clay Overburden (Belterra Clay) Nodular Bauxite, Ferruginous Laterite, Crystallized Bauxite, Crystallized/Amorphous Bauxite, Amorphous Bauxite and, at the base, argillaceous sediments of the Lower Cretaceous Ipixuna Formation.

Mine grade control and production monitoring is based on processing data obtained by logging and sampling boreholes made on a 100 X 100 meter grid and channels made on a 25 X 25 meter grid on the mine fronts.

The mining operation faces two major challenges: a high stripping ratio of 7.6 in volume and a high level of rainfall. The mining system, therefore, needs to optimise waste stripping and allow for ore selectivity. The system developed to achieve these results uses hydraulic excavators and bulldozers for waste stripping, and hydraulic excavators and trucks for ore production.

The mine scheduling developed to design, simulate and sequence the mine on both Paragominas plateaus are described. Several scenarios were analyzed in order to better understand the relationship between the design parameters and the geological resources. The use of specific software tools, the appropriate data format and checks, and the experience of the mine staff were key issues to produce the best results.