The bauxites of Trombetas operate the mines of Saracá V, Saracá W and Bela Cruz, where the ore lies at an average depth of 8 meters and is covered with dense vegetation and a layer of overburden made up by organic soil, clay, nodular bauxite and ferruginous laterite.

The bauxites of Trombetas are associated with the plateaus, high areas with relatively plan ridges and elevations between 200 and 160 meters, which were formed from lateritization processes acting on sedimentary rocks (which contained aluminous minerals) from the Paleogene period (about 40 million years).

The mineralization of bauxite occurs at the top of the plateau and is normally covered by a layer of clay, 4 to 10 meters thick. However, near the edges of the plateaus, bauxite might even be outcropping in the soil.

Bauxite is a rock made up of different minerals (gibbsite, kaolinite and quartz), the first being the source of aluminum.

A typical bauxitic profile consists of the following horizons:

- 4 - organic soil with a maximum thickness of 0.5m;
- 3 - yellow clay covering most bauxitic profiles, consisting of kaolinite (80%) and quartz, with a maximum thickness at the center of the plateau, decreasing to its edges;
- 2 - bauxitic layer with an average thickness of 4 m, subdivided into three subhorizons:
- 2c – nodular bauxite;
- 2b – ferruginous laterite;
- 2a – massive to granular bauxite;
- 1 - variegated clay.

The MRN mine is an open-cut strip mining operation that has an 18Mtpa installed bauxite capacity.

For bauxite to be mined out, first it has to be stripped off. This operation is done in a sequential manner in regular strips, where the overburden is excavated and dumped into the adjacent strip in which the ore was previously mined out.

After being mined out, the ore is loaded on trucks and transported to the crushing plant, where it is reduced to a particle size of up to three inches. From the crushers, the ore is transported on conveyor belts to the washing, cycling and filtering facilities.

As a result from this beneficiation process, approximately 25% of solid mass, known as bauxite tailings, is generated. The tailings are dumped into reservoirs built in mined-out areas on the Saracá plateau.

Once beneficiated, the ore is transported from the mine to the port along a 28-km-long railway. In this operation, trains with 46 rail cars each are used.

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