Verificação de desempenho dos sistemas de filtragem de resíduo bauxita por tambor e prensa como alternativa para barragens

Abstract

Tailings dams generally function as a reservoir of tailings and water, due to existing disposal methods, this is due to the characteristics of the processing processes of mining companies and refineries, which use a very high concentration of water in this process, resulting in tailings with low solids contents and that offer risks in the disposal and that also directly impact the environment in which they are inserted. In view of the occurrence of accidents involving tailings dams in Brazil and worldwide and the need to reduce the impacts caused, mining companies and ore processing industries have invested in innovative technology that promote waste dewatering, making them drier and providing a safer form of disposal. However, in this direction, this study presents the methods of disposal of wet and dry tailings in the form of landfills, obtained from filtration systems, highlighting the advantages and disadvantages of the use of the filter press compared to the drum filter for the disposal of bauxite residue. Experimental landfills of bauxite residues from an alumina refinery, located in the state of Pará, were used, which allowed the knowledge of the material behavior after filtering by filter press, when submitted to compaction by track tractor and compactor roller. A qualitative risk analysis of the FMEA type was also analyzed to identify the risks involved in the method of disposal of the filtered residue by drum filter. The residue dewatered through the drum filter reaches an average solids content of 60% at the end of the process and per filter press up to 80%. The compaction tests allowed the knowledge of dry density, optimum humidity and degree of compaction of the material dewatered by filter press, when arranged in the form of a controlled landfill. The two waste filtration systems (Drum Filter and Press Filter) were compared considering the operational, safety and environmental aspects, allowing to know the advantages and disadvantages of each system and the safer disposal method, less impacting on the environment and less susceptible to structural problems. The FMEA analysis identified the main triggers and failure modes related to geotechnical risks in the operation of the waste system with drum filter, for disposal via construction of platforms. The aspects of "insecurity" and "dam galling" were analyzed and generated the risk matrices and their consequences / effects. The results "High Risks" helped to define the change in the filtering system and arrangement method.