Water management

(Figure # 1) The schemes for the water management at the underground mines
Figure # 1. The schemes for the water management at the underground mines: direct for the single horizon (a) and for several horizons (b), stepped with the pump chambers of the overlying horizons (v).

WATER MANAGEMENT (EN: water pumping, water drainage; DE: Wasserhaltung; FR: exhaure; ES: desague; RU: водоотлив) is the removal of the waters within the underground mines and open-pit mines from the mine workings. In case of the underground development, they distinguish the main water management, which is purposed for the pumping-out of the inflow of the water within the entire underground mine, and the local water management for the pumping of the water from the individual places of the underground mine into the water collectors of the main water management (less often immediately onto the surface of the earth). In the rare cases, there are used the central water management, when several underground mines have the common water management installation, and the regional water management, which is ensuring the water management of the entire region as a whole.

The water management according to the scheme for the pumping of the water onto the surface is divided into the direct water management, when the pumping-out of the water from the main water collector is performed directly onto the surface, and the stepped water management, when the water is pumped from the lower horizons through the shafts (less often through the boreholes) into the intermediate water collectors of the overlying horizons, and then onto the surface (see the Figure # 1).

Less often, there are used other schemes for the water management, for example, with the transfer of the water into the pump chamber, which is positioned above (near the shaft), with the bypass of the water from the overlying horizon, and so on. There belong to the system of the water management within the underground mine: the devices for the regulation of the internal runoff within the underground mine (the small water-diverting ditches, pipelines, and water-transfer pumps), the water collectors, the pumping stations with the water intake wells and water management installations, with the sucking and injecting pipelines. The devices for the regulation of the runoff of the internal waters within the underground mine include the pipelines and small ditches for the diversion of the water into the local and main water collectors.

They place the water collectors and pump chambers within the underground mines, while taking into account the hypsometry of the sole of the useful minerals, the composition of the rocks, the schemes for the unsealing, and other mining-geological and mining-technical conditions. The pump chamber with the water management installations is placed near the water collector, and is connected with this collector using the mine workings. In case of the inflow of the water of more than 50 cubic metres per hour, the main water management system comprises 3 identical pumps (working, reserved, and placed under the repair), each of which is calculated for the pumping-out of the normal daily inflow during 20 hours. The sucking pipe of each of the pumps, in case of the inflow of the water of up to 100 cubic metres per hour, is lowered into the single shared water intake well, while in case of the water inflow of more than 100 cubic metres per hour, the pipes are lowered into the individual wells. For the main water management at the underground mines (see the Figure # 2), there are used mostly the centrifugal multistage se ctional pumps with the horizontal structure, which are tolerating the content of the mechanical admixtures within the water (the particles with the size of up to 0.1-0.2 millimetres) of up to 0.1-0.2%.

(Figure # 2) The scheme for the positioning of the mine workings for the water management within the underground mineThe efficiency of the pumps ranges within the limits of 68-78%. The acid-resistant pumps are used in case of the pH of the water of less than 5, or in case of the content of the free sulfuric acid within this water of more than 100 milligrams per litre, and may be connected in parallel, and in series with the priming and booster pumps. For the local water management within the underground mines, besides the multistage centrifugal pumps, there are also used the cantilevered centrifugal, monoblock, and auxiliary pumps (turbopumps, electric-pump single-screw aggregates, single-stage centrifugal horizontal pumps, centrifugal horizontal cantilevered pumps). During the pumping-out of the non-purified waters within the underground mine (with the solid inclusions with the particle size of up to 20 millimetres), during the cleaning of the water collectors of the sludge, and for the local water management, there are used the sludge pumps (of the vertical type, suspension type, magnetite-sludge type, and so on). For the delivery of the water onto the surface, there are laid within the shaft of the underground mine at least two stands of the injection pipes, namely, one operational stand, and one reserve stand; in case of the two pumps, which are working simultaneously, there are laid three stands of the pipes. Every stand is calculated for the yield of the normal daily inflow during at most 20 hours; in case of the increased inflows, there are used all the stands.

The water management installations are equipped with the apparatuses for the automation, monitoring, and protection. The apparatuses for the automation ensure the automatic priming, starting, and stopping of the pumps, depending on the level of the water within the water collector, the alternating work of the pumps, the automatic starting of the reserved pumps in case of the emergency rise of the level of the water within the water collector, and in case of the malfunction of the working pump, the remote monitoring and signaling about the level of the water within the water collector. At the underground coal mines, which are dangerous because of gas and dust, there are used the apparatuses for the automation with the explosion-protected and dust-protected structure. As the instruments for the monitoring of the hydraulic indicators, there are used the manometers and flowmeters. For the protection of the pumps during their stopping against the water hammers, there are used the speci al shock absorbers. The major ways for the further perfecting of the water management at the underground mines are: the decreasing of the volume and the simplification of the structure of the water collectors, or the usage of the water management without the chambers, with the vertical submersible pumps and airlifts; the perfecting of the means for the water management for the pumping-out of the polluted water onto the surface; the complete mechanization of the labour for the transport of the equipment, for the mounting of the pump aggregates and pipelines, for the cleaning of the water collectors, and so on.

In case of the opencast development, the system of the water management comprises the device for the regulation of the internal runoff within the open-pit mine, the water collectors, the pump stations with the water management installations, and with the injecting pipelines. The devices for the regulation of the internal runoff within the open-pit mine include the loads for the prevention of the deformations of the loose rocks at the places with the seepage of the underground waters on the slopes, the water diversion ditches or pipes for the collecting of the water on all the benches, and within the goaf space, and for the diversion of the water initially into the local water collectors, and then into the main water collectors.

(Figure # 3) The schemes for the opencast and underground water management at the open-pit mineDepending on the location of the main water collectors, the water management within the open-pit mine is divided into opencast, underground, and combined, which is including the elements of opencast and underground (see the Figure # 3).

In case of the opencast water management, they place the water collectors with the pump stations at the lowest elevations of the open-pit mine. The water collectors of the main water managements are constructed in case of the inflows of the water of more than 50 metres per hour, and are calculated for the reception of at least 3 hours of the normal inflow of the water. They construct the pump stations near the water collectors, and equip these pump stations with the water management installations, the performance of which must ensure the pumping-out of the maximal daily inflow of the water during 20 hours; additionally, there are provided the reserved pumps. Within the regions, where the inflows of the rainstorm waters may exceed the normal inflows by several times, they construct the pumps of the main water managements as the floating pumps.

In case of the opencast water management at the water-flooded open-pit mines, they use mostly the high-performance low-pressure pumps. The injecting pipelines are laid on the non-working sides of the open-pit mines. During the winter time, the water management installations, injecting pipelines, and also the ditches for the diversion of the water, are protected against the freezing. In case of the underground water management within the open-pit mine, the water is pumped or is diverted into the special water diverting mine workings (drifts) for the drainage, which have been penetrated with the inclination towards the water collector with the pump chamber, from where this water is pumped-out using the pumps through the water management shafts or boreholes onto the surface, and into the superficial watercourses or water bodies. In this case, there are used mostly the same pumps, as in the case of the water management within the underground mine. During the penetration of the underground mine shafts, and of the incision trenches, there are used the auxiliary pumps (the centrifugal spiral, sectional, cantilevered, turbopumps, and so on), with the performance of 5-130 cubic metres per hour, and with the pressure of 30-100 metres.