Project: Dust suppression installation for a mine

The installation was a pilot plant.

Pump Room

A 10’ container is used as a pump room, this houses the main pump, the chemical injection pump and the agitator pump for the chemical.

The pump room also includes key components of the pipe network and the command box such as the main shutoff valve, the bypass valve, the pressure gauge, the pressure switch and the control box.

Water tank

The system comprises a 20 foot tank container as a clean water reservoir instead of pumping directly from the quarry.  Should the filter get full of debris, the system will keep pumping from the tank/reservoir while maintenance is being done on the filter.

 

Chemical Tank

Calcium powder and CMS liquid will be mixed in a 5000lt vertical plastic. This tank is equipped with an agitator to prevent the mixture from settling.  The mixture will be injected in the main pipeline by a metering pump. Venturi inducers are not recommended as they have high pressure loss (+/- 35%).

Agitator inside the tank.  This tank size could be 2000lt capacity which covers x12 (7000lt batches) dust suppression mixes.

Pipe Work

The main pipe section connecting to the median middle road main pipe is to be buried 400mm deep as indicated on the drawing.

 

 

The median middle road main pipe will be supported by the concrete blocks which will supports the nozzle pipes as well.

The nozzles are mounted on a discharge manifold which is 20m long. The discharge manifolds have a drainage/service valve, a filter and a solenoid valve.  Refer to the figure illustrated above.

 

Nozzles

The most important part of the system is the nozzle head. The nozzles will be mounted on the discharge manifold on the middle camber as indicated on the illustrations above. The nozzles have a flow rate of 16l/min at 6 bar.

Control System

The dust suppression system is essentially a mist fixed system designed to reduce dust emission in the environment along the mining roads.   The road length is divided in road area and each road area is equipped with a motion sensor and a moisture sensor which activates or stops the respective road area.

Motion sensor

As soon as the mining vehicle enters a road section (e.g 20m x 35m), the motion sensor will trigger the respective solenoid and will discharge a mist curtain along the road area section for a period (time and distance of the road area subjected to change after testing). This will save water and chemical discharged by focusing only on the area generating dust due to traffic.

Moisture sensor

This is a key component of the system. After the right soil moisture is reached, this will prevent the motion sensor to activate the road area solenoid valve thus preventing mud that can be caused due to excess liquid discharged.  The system will only be able to energize the corresponding solenoid valve when the soil moisture drops.

Pressure switch

This component prevents damage of the pump(s) due to continuous pumping without discharging when there is zero traffic on the road. The system will pump and inflate the pipe network to a maximum of 20bar and it will automatically open the bypass line once the pressure exceeds 20bar.

The water tank is equipped with a float switch, this will activate or deactivate the filling pump as the water level is minimum  or maximum.

The system will be controlled from the pump room via a control panel. Uninterruptible power supply should be provided.

The supply and installation of the power cables will comply with the relevant statutory authority. This may involve marking tape, cable warning slats, bricks located 300mm above the cables, etc as required.

Control cables (solenoid) running from the control box to the valve and the humidity sensors will comply with the following:

  • All cables will be tested physically and electrically before installation.
  • All cables will be continuous runs and there will be no random joints in the field. Cable joints will only be accepted at junction boxes and at solenoid valves terminals.