Update of Hydrogeological Model for Underground Mine Expansion, Baltar Mine
CLIENT
Votorantim Cimentos
LOCATION
Votorantim, SΓ£o Paulo State, Brazil
TIMEFRAME
2019
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Challenges
The Santa Helena Unit, a mining complex of Votorantim Cimentos, located in the municipality of Votorantim in the state of SΓ£o Paulo, comprises three inactive open-pit mines and one active underground mine, named Baltar, Placa, and Pastinho. The project aimed to update the conceptual and numerical hydrogeological model of the Baltar underground mine, with new numerical simulations based on current mining plans. The objective was to estimate the water inflow volumes into the excavations as mining progressed, ensuring the viability of Votorantim’s planned future expansions.
Solution
The project involved compiling and analyzing geological model data, mine topography (2016-2019), historical precipitation, hydrogeological monitoring, underground water pumping data, hydrochemical data, and mining plans for 2020-2051 to review the conceptual hydrogeological model as the basis for a numerical flow model. The 2012 numerical flow model, originally in a local coordinate system, was updated to reflect new expansion plans by adjusting the hydrostratigraphic geometry, mining areas, recharge rates, and recalibrating with new parameters. Simulations were then conducted for the current (2019) mine condition and future mining sequences (2020-2051).
Results
The update of the numerical model allowed for more accurate simulations for the mine expansion plans through 2051. A staged pumping system was planned to ensure the mine’s operational viability, optimizing groundwater management and supporting Votorantimβs new mining plans. The simulation estimated a maximum groundwater inflow into the mine starting in 2046. Since the water will need to be pumped from a significant depth (around 600 meters) to the surface, a multi-stage pumping process will be required. This could be achieved, for example, by opening vertical shafts that would help move the water from one level to another within the underground mine.