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Utilisation of bauxite residues

Utilisation of bauxite residues

The management of solid waste is perhaps the greatest overall challenge that MYTILINEOS is facing. Out of a number of concerted actions that we have carried out successfully, our initiative regarding the utilisation of bauxite residues in ALUMINIUM OF GREECE stands out. To achieve this, the company made a total of €10 million of environmental investments between 2006 and 2011 – its largest ever investment of this type.

The project

These investments concerned the installation of four filter presses to treat bauxite residues, in two separate buildings, together with their respective auxiliary installations (feeding tanks, compressor tanks, air compressors, disposal area, conveyor belts etc.). The operation of the three presses covers the needs for drying bauxite residues, while the fourth one, which is installed in the same premises and has the same treatment capacity, is used as backup for the other three in the event of a breakdown in the future.

 

Why filter press technology?

This technology is today the best available technique for the treatment of red mud globally, as it reduces disposal volumes on land and allows direct transport (e.g. ship loading) of the dry bauxite residues (ferroalumina) intended for a variety of uses, such as an additive in cement and in roof tiles, a substrate for roads and controlled landfills etc.). It is also the safest technique for the treatment of these residues in environmental terms, as the ferroalumina produced is 72% dry, in contrast to other technologies that result in the production, handling and disposal of slurry, at great environmental risk in the event of a damage to the disposal area basin.

Results from the operation of the filter presses

The first press, installed in 2006, went immediately into operation, with the aim to increase every year the quantity of bauxite residues dried and disposed in the specially configured area. With the gradual installation of the other filter presses, treatment output rates increased with every year, until 2012 – when treatment of 100% of bauxite residues was achieved and their disposal in the sea was discontinued altogether.