In the first years of the commercial operations of MRN, the waste that resulted from the enrichment of bauxite was thrown into Batata Lake. This was done because at that time there was no technology available that could avoid the silting up of bodies of water or the flooding of large areas of forest.

In 1989, after five years of studies and construction work, the enrichment unit was transferred from the Port area to the Mine. This was when the waste started to be returned wholly to the mined areas. About US$ 85 million was spent on this project.

The current system consists of waste tanks specially constructed in mined areas, where the waste is compacted without use of any chemical additives. The water that is recuperated from the compacting process is returned to the bauxite ore enrichment unit, through a closed circuit.

Once full, the waste tanks are revegetated with species native to the region. The first stage in this process is hydro sowing with native leguminous plants, inoculated with bacteria, to speed up the process of nitrogen fixation in the soil, and absorption of water and nutrients.

The next step, when the waste surface is already more consistent, is to plant cuttings and cast seeds also using native species. The evolution of this process has been highly satisfactory.



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