Dewatering solutions for mining applications

Dewatering solutions for mining applications

Open-pit and underground mines eventually fill with water unless the water is kept away by different pumping arrangements. The design of these systems must take into account several factors, such as capacity, reliability and operating cost. Xylem possesses both the products and the engineering know-how to provide solutions for many mining dewatering applications.

1 Active dewatering

Why: It is sometimes necessary to lower the water table around an open-pit mine. This stabilizes the walls and reduce the need for dewatering inside the mine.

How: Deep wells are drilled around the mine and fitted with submersible borehole pumps. Alternatively, the wells are fitted with pipes connected to an automatic selfpriming pump.

Products: Xylem’s Lowara size 4”–12” borehole pumps. Godwin diesel or electric selfpriming pumps.

2 Drill hole drainage

Why: Before drill holes are charged with explosives, they may have to be drained of water.

How: A borehole pump can be used to remove the water before charging.

Products: Lowara borehole pumps, size 4” and up.

3 Open-pit drainage

Why: Surface water and groundwater that enter the pit have to be removed continuously in order to maintain production.

How: One solution is to use a raft and fit it with a submersible drainage pump or a selfpriming pump, where the latter can also be ground-based.

Products: Flygt submersible drainage pumps. Godwin diesel or electric self-priming pumps.

4. Main drainage

Why: The main drainage is where surface water, ground water and production water are collected for initial treatment and transportation to the surface directly or in stages.

How: There are two installation methods – dry or submersible. While dry-installed multistage pumps require space underground for settling basins, submersible drainage pumps only need a small sump. However, multistage pumps offer higher head than submersible pumps.

Products: Vogel and Düchting dry-installed multistage pumps. Flygt submersible drainage pumps.

5 Face and stage dewatering

Why: Face and stage dewatering pumps remove ground and production water. Because the front of a drift moves forward as the mining continues, there is no time to make sumps for pumps to operate in. This is the most demanding pump application with high solids content and low water levels.

How: The solution is to use relatively small portable submersible pumps. They must be able to operate also when the inlet isn’t quite submerged, allowing in air along with the water (snoring). The water is taken to a sump further back in the drift, where a fixed installation transports the water to another stage or directly to the main drainage station.

Products: Flygt submersible drainage pumps.

6 Shaft bottom drainage

Why: Since the shaft bottom is the lowest level in a mine, water that isn’t collected elsewhere will eventually end up there.

How: A dewatering solution for the shaft bottom drainage typically consists of a sump with submersible drainage pumps in a fixed installation. When solids are a problem, submersible slurry pumps can be an alternative.

Products: Flygt submersible drainage pumps or slurry pumps.

7 Slurry tailings handling

Why: Water from a mine or an ore concentrating plant is taken to sedimentation basins where, through gravitation, solids settle to the bottom of the basin.

How: One way to remove the sediment is to pump it out along with some of the water content in the form of slurry. This can be done with the help of submersible slurry pumps.

Products: Flygt submersible slurry pumps. Slurry removal pump systems.

8 Recovery of water

Why: Water is necessary for mining as well as ore concentration processes. Often, it is an advantage to keep the water in a closed loop. This requires that the water be recovered from the sedimentation basins and the tailings dam.

How: Recovery of water can be made through a permanent pump station or by suspending pumps from a raft. In both cases the pumps are submersible and draw surface water from the basin.

Products: Flygt submersible drainage pumps or wastewater pumps.

by Åke R. Malm