Modelamento numérico do fluxo subterrâneo atual e simulações de cenários futuros da mina de Morro Agudo, Paracatu-MG

Abstract

The numerical modeling of underground flow of Morro Agudos´ mine, property of Votorantim Metais Zinco (VMZ), Paracatu-MG, used data from hydrometeorological monitoring campaigns to calibrate the actual scenario and simulate future pumping scenarios of this mine, using Visual MODFLOW 3.1 software. The study area is located in Paracatu-MG and in external portion of Brasília Fold Belt at west margin of São Francisco Craton, the mine is inside metasedimentary sequence of Vazante Group, composed by dolarenite, dolarenitics and dolomitics breccias of Morro do Calcário Formation. In June of 2011 was registered 255m³/h of water springs inside underground mine, this value is nearly the maximum capacity, 270m³/h, of Wastewater Treatment Plant. So, it was necessary make some simulations to predict the increase of this pumping rate until the year of 2017, following expansion plans, purposing take effective actions in the water treatment. Was used monitoring data given by technical team of VMZ to update the concept hydrogeological model and make a new calibration of numerical model. After calibration, those scenarios were simulated from 2012 until 2017. From those scenarios were obtained an increased pumping rate that will achieve to 530m³/h. Of this value was subtracted the pumping rate of "Projeto Água Limpa" (Clean Water Project) and added the inside flow, reaching the final pumping value of 504m³/h. This pumping rate will be considered in the planning of the new Wastewater Treatment Plant to supply necessities until 2017. This value can be decreased with rising of "Projeto Água Limpa", but depends of mutual efforts from Hydrogeology, Geology, Environmental and Operations sectors. Mine´s dewatering it´s not interfering in stream flows around the mine, because all water is pumped to surface and returns to original stream, without being prejudicial or causing environmental impacts. As is a fissural aquifer it´s impossible to affirm if galleries will cross an expressive fractural zone, increasing in a large way the pumping rate simulated by this work.