Desempenho de cobertura seca em escala piloto para abatimento da DAM gerada por rejeitos de carvão

• Autor(a) principal: Souza, Vicente Paulo de
• Data de Publicação: 2009
• Outros Autores: Possa, Mario Valente, Soares, Paulo Sérgio Moreira, Soares, Anderson Borghetti, Bertolino, Ana Valéria Freire Allemão, Souza, Marcia Raquel Ronconi de
• Tipo de documento: Artigo de conferência
• Idioma: por
• Título da fonte: Repositório Institucional da Universidade Federal do Ceará (UFC)
• Texto Completo: http://www.repositorio.ufc.br/handle/riufc/69163
• topic: Cobertura seca; Carvão; Pirita; Percolação; Drenagem ácida de mina

This paper presents the design of a dry cover, in pilot scale, and the evaluation of the results obtained in the first twenty months of monitoring. The dry covers were designed by CETEM in a prototype unit installed in the Carbonífera Criciúma S/A, in the city of Forquilhinha/SC. The system is composed of four pits of 110m³ each, with lysimeters (6,28m³) filled with waste from a coal beneficiation plant. Three of the four cells received differet covers, while in one of them the waste was exposed with no cover, to be the reference to compare the performance of the cover as to the acid generation and volume of the effluent. The materiais and the thickness of the layers used in the cover systems (30cm), as well as the position of the lysimeters and dimensions were determined for numeric modeling. The following conditions are being studied: (a) Cell I - waste as is; (b) Cell 2- waste covered with a mixture of fine and coarse wastes; (c) Cell 3- waste covered with compacted clay and organic soil, and finally, (d) Cell 4- waste covered with ash compacted, compacted clay, ash compacted and organic soil. ln each covering layer was installed temperature, water content and suction sensors. The long-term study objective is to select the ideal type of cover for the DAM abatement that could be applied for others similar wastes of that region. Acid waters from lysimeters II and I present pH in the range 0.70 - 3.0, while in lysimeters III and IV. pH values oscillate in the range 6.40- 7.30. For the dissolved species, Mn concentrations are oscillating in the range 50-600 mgL^-1 for lysimetcrs I - lI and 4.0- 14.0 mgL^-1 for the lysimeters III - IV. Values for S04 concentrations oscillate between 90 - 215 gL^-1 for lysimeters I - lI and 1 - 3 gL^-1 for lysimeters III - IV. Analyzing the above results it is observed that the overall quality of percolate water from the covered waste is much better than that of percolate water from uncovered. ln way to reach larger consistence in the analysis and interpretation of the chemicals phenomena that are being processed in the experimental cells the next phase of the study in the Prototype Unit will apply geochemical and water balance models.