AnsPit assists hydrogeologists in mine dewatering projects to calculate open pit inflow and predict (optimize) operation of a dewatering systems
Dewatering predictions to meet mine schedule and assess environmental impacts usually require a mathematical model. While most of mine feasibility studies require numerical models to simulate complex groundwater processes, less detailed evaluation stages can be conducted using simplified approaches such as that in AnsPit.
Pit inflow
Calculations for open pits inflow are based on standard analytical solutions for the following hydrogeological conditions:
– Confined aquifer;
– Unconfined aquifer;
– Confined-unconfined aquifer;
– Leaky aquifer.
Most schemes account for I-st or II-nd types of boundary impacts. The aquifer can be modelled as infinite, bounded, stripped or radial (circle-bounded).
Mine dewatering systems design
When an open pit is dewatered using vertical wells, ANSPIT can assist in design of well field. The module calculates abstraction rates that are required to achieve dewatering targets (i.e. water level drawdowns on pit walls or other locations). Abstraction rates are calculated for specific layouts that are pre-selected or user-defined. Drawdown targets are assigned at the pit center or at others selected locations. Module is based on windows operating system.
Case Studies
Depressurization study at Porgera gold mine, Papua New Guinea
Client: The Porgera Joint Venture
Objective: Plan depressurisation tests on pit benches
Method: Hydrogeologist Workbench of ANSDIMAT was used to predict pore pressure reduction caused by Horizontal Drain Holes
Calculation of pit inflows for different stages of Life of Mine
Client: KAZ Minerals (Copper deposit in Kazakhstan)
Objective: Calculate inflows into an open pit at different stages of mine schedule
Method: "Pit inflow" dialog box in ANSDIMAT Hydrogeologist Workbench
Optimisation of dewatering schedule for iron ore mining, Western Australia
Client: Iron ore mining company, Australia
Objective: Optimise operation of an existing dewatering borefield for the pit development schedule
Method: AMWELLS model was developed and calibrated to water level measurements. The model was then used for management and optimisation of dewatering operations
