PROJECTO POCI/ECM/60439/2004 – RESPIROMETRIA DA LIBERTAÇÃO DE ÁCIDOS E A UTILIZAÇÃO DE COBERTURAS CONSUMIDORAS DE OXIGÉNIO COMO MÉTODO DE PREVENIR EMISSÕES A PARTIR DE ARMAZENAMENTO DE RESÍDUOS; Entidades Participantes: Cigar, Centro de Química (CEQ/UP), INETI. Participantes: António Manuel Antunes Fiúza, Maria Cristina da Costa Vila, Aurora Magalhães Futuro da Silva, Alexandre Júlio Machado Leite, Joaquim Eduardo Sousa Góis, Cristina Maria Fernandes Delerue Alvim de Matos, Maria Aurora Soares da Silva, Paula Helena Maia Costa Mendes Freire. Financiamento (3 anos): 45 000€.
RESPIROMETRY OF ROCK ACID DRAINAGE AND THE USAGE OF OXYGEN CONSUMING COATINGS AS A MEAN OF REDUCING ENVIRONMENTAL EMISSIONS FROM TAILINGS DISPOSALS Classification: VERY GOOD
The most important environmental problem originated at the tailing disposal of residues originated by the ore processing is the acid rock drainage. It is originated by the oxidation of sulphides, created at a great extent by the activity of aerobic autotrophic bacteria, leading to the production of sulphuric acid and the subsequent leaching of heavy metals with corresponding environmental dispersion originated by transportation by superficial flow and infiltration. In 2003 the proponents of this project made for the National Inventory of Industrial Residues a critical generic survey of the situation concerning the metallic and radioactive ores in Portugal, and several critical environmental impacts were listed.
The kinetics of generation depends on the temperature, oxygen concentration, pH, bacterial activity, type of sulphides and size distribution. There are several actions which minimize this negative environmental impact but the prevention of the generation is the most effective. Several solutions are possible but the oxygen consuming coating, conjugating a low permeability with high moisture content, acting as a barrier to the oxygen diffusion, and with a simultaneous high concentration in organic matter, whose biodegradation consumes the oxygen reducing its transportation and avoiding the autotrophic bacterial activity, constitute the best possible way of avoiding the reactions.
It is aimed in this project to reach the following objectives using mining residues from a location which was classified with an environment negative impact: