Open-Pit Mine Dewatering Based on Water Recirculation—Case Study with Numerical Modelling

Abstract

The layout of the dewatering system in open-cast mining must be adapted to mining assumptions and to the size of expected inflows, which, in turn, depend on natural conditions and the operation of other mines and groundwater intakes, affecting the arrangement of the hydrodynamic field. This case study analyses possible dewatering solutions related to a change in the mining drainage system: decommissioning by flooding of a depleted deposit and dewatering of a new one located in the vicinity. As part of numerical modelling, a solution was sought to minimise the environmental impact of drainage. Forecast calculations for two drainage alternatives were made. One of the solutions follows the classic approach: independent dewatering of the new excavation. The second solution assumes the recirculation of waters from dewatering of the new mine through their discharge into a closed and flooded pit located in the vicinity. The results of the forecasts for both variants point to the modification of the hydrodynamic field resulting from expected volumes of inflows and different environmental effects. The use of numerical simulations assisted the selection of the optimal dewatering solution.

Influence of Long-Term Mine Activity on Hydraulic Relations between Separate Hydrogeological Units—New Aspects of Regional Water Circulation Assessment

“…In all documentation and scientific publications to date, the two structures have been treated separately and analyzed independently. Separate, independent functioning digital hydro-geological models were developed for each of these structures [26,[35][36][37], whose concepts and realized predictions originally did not raise any objections.…”

“…On an area of about 27 km 2 , four mines of different owners are adjacent to each other, conducting exploitation on 6 pits until recently. Currently, after the water reclamation of the Radkowice-Podwole pit [26], there are five operating, on the deposits: Jaźwica, Kowala, Kowala Mała, Trzuskawica (two pits Trzuskawica and Kowala; Figure 1). In the northwestern part of the structure, the Ostrówka deposit is in operation, and the neighboring Ołowianka-1 deposit is in the process of obtaining the necessary documents.…”

“…Helpful in such applications are methods of mathematical modeling of groundwater filtration processes, considered one of the most accurate research methods in hydrogeology for predicting the distribution of the hydrodynamic field, including differentiated stresses [9][10][11][12]. Numerous examples demonstrate the utility of the method in solving inflow issues underground [13][14][15][16][17][18][19] as well as in open-pit mining [20][21][22][23][24][25][26]. In practical applications related to groundwater filtration modeling taking into account mine drainage systems, both the finite difference method (based on simulators of MODFLOW family [27]) and the finite element method (FEFLOW program [28]) are used.…”

Spatial and Temporal Distribution of Groundwater in Open-Pit Coal Mining: A Case Study from Baorixile Coal Mine, Hailaer Basin, China

“…Open-pit coal mining groundwater drainage can cause groundwater disturbance [9,[11][12][13][14], and the existing articles on groundwater in open-pit mines mainly focus on the prediction of groundwater inflow [2,[14][15][16][17], groundwater as a disaster-causing factor for the safety evaluation of open-pit mine slopes [18][19][20][21][22], groundwater chemistry [5,6,23], and ecological evaluation [3,4,23,24]. There are many articles on the change and prediction of groundwater inflow caused by open-pit mining from the perspective of numerical simulation, such as Soni and Manwatkar [16] used the modflow model to simulate and predict the groundwater inflow and groundwater flow field changes in an open-pit coal mine in India under different mining conditions.…”

“…Zhao et al [2] used the surfact model to assess the groundwater impact of an opencast coal mine in New South Wales and predicted the inflow of groundwater into the mining area during the entire project mining cycle. Ró˙zkowski et al [14] used numerical calculation and simulation of groundwater inflow in open-pit mines to formulate a reasonable drainage scheme. Haque et al [9] 2 Geofluids assess the vulnerability of groundwater due to open-pit coal mining using a drastic model.…”