Prevention of flammable gas and coal dust explosions in collieries

Prevention of flammable gas and coal dust explosions in collieries

Acceptable levels

Flammable gas concentration

A flammable gas concentration of less than 1,4%.

Last through road

The last through road in a coal mine will constitute the closest holing to the working faces between two companions, which carry a unidirectional flow of air from the intake to the return of the section.

Recirculation

When any amount of air which has been delivered by a particular ventilation system, ventilating a heading, re-enters the inlet of that system.

Return air

Air which has scrubbed the face of a heading.

4. PREVENTING THE ACCUMULATION OF AN EXPLOSIVE CONCENTRATION OF FLAMMABLE GAS

4.1. Ventilation system

4.1.1. Primary ventilation

The purpose of primary (general section) ventilation is to ensure that ventilation systems are in place to ensure that sufficient air reaches the last through road /longwall or shortwall face to prevent the possibility of secondary ventilation systems recirculating.

To achieve this objective, the following is required:

4.1.1.1. Mechanical miner sections

4.1.1.1.1.

The average air velocity in the last through road should be at least 1 m/s, with a minimum velocity not less than 0,6 m/s.

4.1.1.1.2.

Relative to the heading where the machine is cutting, a minimum velocity of 1 m/s should be maintained in the split that is upstream with regard to the ventilation flow.

4.1.1.1.3.

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

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