Prevention of flammable gas and coal dust explosions in collieries

Prevention of flammable gas and coal dust explosions in collieries

4.1.1.1.4.

Sufficient air flow shall be provided to ensure compliance with specified gas and dust concentrations.

4.1.1.2. Conventional drill and blast sections

4.1.1.2.1.

The average air velocity in the last through road , measured in each split, should be at least 0,6 m/s.

4.1.1.2.2.

The auxiliary force fan should not recirculate and should be so positioned to discharge fresh air directly on to the working face.

4.1.1.2.3.

Sufficient air flow shall be provided to ensure compliance with specified gas and dust concentrations.

4.1.1.3. Longwall and shortwall sections

4.1.1.3.1.

The average air velocity measured along the face should be at least 1 m/s.

4.1.1.3.2.

Sufficient air flow shall be provided to ensure compliance with specified gas and dust concentrations.

4.1.2. Secondary ventilation

Secondary ventilation may be defined as the air moving mechanisms (auxiliary fans, spray fans and dust scrubber fans) being utilised in a coal winning heading or face. It is in this working place where all three ingredients required for an explosion (fuel, source of ignition and oxygen) may be present, and hence it is this part of the section into which effective ventilation should be directed.

Of the three ingredients only one is required to be removed from the equation to prevent an explosion from occurring. This is achieved by efficient ventilation systems.

To satisfy the objectives mentioned above, the secondary ventilation system in mechanical miner sections should aim:

4.1.2.1 At diluting the flammable gas and the dust generated to acceptable levels.

4.1.2.2 At rendering the flammable gas and dust generated harmless and to remove them in a controlled manner.

4.1.2.3 At capturing the dust and convey it to a cleaning mechanism.

The system which is employed should ensure that acceptable levels (dust and flammable gas ) are maintained in the heading at all times.

On board force system e.g. spray fans and on board or off board dust scrubber units should be in operation prior to the commencement of any mining with a mechanical miner.

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