Mine Water

(pit water), subterranean or surface water that enters mining excavations and undergoes physicochemical changes during mining operations. Mine water is produced when subterranean waters of various horizons mix and interact with the mine atmosphere and the rocks uncovered by mining excavations. In its chemical composition and total mineralization, mine water differs from the subterranean water surrounding the mine. This is due to oxidation of the mine water, leaching of rocks, change in gas and bacterial composition, and the pollution of mine water by petroleum products and oils.

The excavations of operating mines are usually flooded. The water flow varies greatly—from tens to several thousands of cu m per hour—depending on the nature of the rocks composing the deposit and the proximity of surface water drainage. For example, in regions of fissured and karst limestones, the flooding of mines may reach several thousand cu m per hr.

The composition of mine water depends on the type of mineral being mined and the depth of the deposit. In coal deposits, for example, when deposits of sulfurous coals and pyrites are being worked, an acid water is often produced that is highly corrosive to metals and concrete. In deposits of complex ores, the water is often enriched by copper, zinc, and lead. The temperature and total mineralization of mine water increase as mine depth increases. Under certain conditions, the temperature of the water is anomalously high because the mining excavations release subterranean water from great depths. Water inflow to segments being worked is reduced by a water drawdown system. This improves the organization of extraction and excavation-cutting operations, increases labor productivity, and keeps subterranean fresh water from becoming polluted. Before disposal, mine water undergoes preliminary purification through the use of purification equipment. The proper designing of purification equipment requires knowledge of not only the expected water inflow but also the composition of the mine water; detailed exploration work must therefore be done to predict the quality of mine water.