Coal Mining Dewatering Solutions with Wedge Wire Screens

Some time ago I past a conveyor belt system from the mine to a power station while it was raining- It was not long after I stopped that the moters were overloaded and stopped.

You sure face a lot of problems but keeping water usable is also a challenge especially in arid countries.

In South Africa we have a special water use (license) for removing, discharging or disposing of water found underground if it is necessary for the efficient continuation of an activity or for the safety of people.

De-watering may cause water resource pollution by lowering the water table and depriving poor people relying on springs and shallow ground water from access to domestic water (guaranteed by the Constitution).

The other possible water resource pollution is that when pyrites are found with or near the coal seam.

Pyrite in the presences of water and oxygen forms an acid which could render the water unusable.

I worked on a closed system in a 7MT coal mine supplying a thermal power station.

There were settling dams to remove silts before the water was discharged into the stations cooling water storage dam.

The desilting dams were drained by pumps back to either the raw water storage or the thickener in which the PH was controlled by the addition of lime. The turbidity and PH were controlled by adding flocculant and lime to the washplant outflow to the thickener.

The takeoff from the thickener was pumped into a disused pit from which the water was sent back via channels to the desilting dams making the whole system a closed loop. All the controls were carried out by PLCs and radio links.

The mine went from importing up to 5ML of water a day to being self sufficient requiring no external water makeup.

Dewatering in the plant was carried out by high speed vibrating screens, centrifuges, spirals and vibrating screens.

IMHO:

I think the most danger to people and environment is the integrity of the containment dams.

When they collapse due to shoddy construction or poor maintenance, many lives are lost and the pollution is off the charts.

The lack of maintenance is usually due to cost restraints on man hours spent, and when repairs are indicated, they kick the can on down the road to a further date.

The construction quality is affected by compromising the quality of materials and labor.

Greed($$) is the main cause of pollution everywhere.