Abatimento de drenagem ácida de mina com cobertura de entulho de construção civil : uma proposta de reabilitação de uma antiga mina de pirita.

In Ouro Preto-MG, piryte was wxploited at an old mine, during the decade of 30 and 60, of last century for the production of sulfuric acid. Today this mine, with great environmental impacts, is an area of illegal deposition of building site debris. In this mine, points of emergence of water with inferior pH to 3.0 were observed, characterizing the production the acid mine drainage (AMD). It is considered as great environmental impacts that concerns where sulfide minerals are mined. When the acid drainage enters in contact with various minerals, it liberates and mibilizes some elements. This may cause contamination in different kinds of environment. In these sites the acidification process is accelerated by exploitation activities that expose great volumes of materials to the action of the atmosphere. In sprite of the piryte to be the main responsible mineral for the acidity, bivalent metals exist (Fe, Zn, Cd, Pb, Cu and Ni), presents in other minerals responsible also for the production of acids in similar chemical reactions the oxidation of the piryte. When the acid production is identified, the best is to generate a strategy of effective control of costs during the planning of the mine. The works regarding the AMD have concentrated in the description of the problem, of the evaluation of the potencial of acid production and in the obtaining of new treatment technologies. Therefore, the objective of this work was to confirm short term the acid generation in the Piryte Mine's, to propose a treatment and rehabilitation alternative of the area, with the debris use lime as covering system for reduction of the acid drainage through the use of the leaching columns. The obtained results show that the debris addition was efficients in the reduction of the acidity (superior to 90%), concentration of metals and sulfare. The use of the debris in the control of AMD, can be considered as a promising alternative in the reduction of AMD due to the low cost and being an interesting alternative for the great cities that don't possess areas for deposition of construction debris.