Approved by the order of the Minister of Emergency Situations of the Republic of Kazakhstan of July 25, 2008 No. 132

The temporary instruction on security measures and the prevention of explosions of sulphidic dust on the underground mines developing piritsoderzhashchy ores

Chapter 1. General information about explosions of sulphidic dust

1. The sulphidic dust which is formed in case of explosive destruction of strong, piritsoderzhashchy ores can form explosive concentrations (aero suspensions) in air and ignite in case of impact on it thermal source with temperature at least 800 Pages.

2. Burning of sulphidic dust depending on intensity of the initiating impulse can proceed in the different modes:

stationary burning with speed of distribution of flame from several m/s to the first tens of m/s;

the explosive non-stationary burning (deflagration) extending with speed of smaller speed of sound in air;

detonation, with speed in several km/s.

In miner conditions the most characteristic forms of burning of dust are stationary and explosive (deflagration).

3. Exothermic reaction of oxidation of pyrite which main products are sulphurous gas (SO2) and oxides of iron (Fe2O3 and Fe3O 4) is the cornerstone of explosion (flash) of sulphidic dust.

4. Source of initiation of explosions (flashes) of sulphidic dust are explosive works.

Explosion (flash) of sulphidic dust in the mine is followed:

formation of considerable amounts of sulphurous gas which concentration in excavations can reach 1% and more;

distribution of flame on excavations on distance to 25 m (in case of shpurovy otboyka and secondary crushing of ore superimposed charges) and to 100 m (in case of detonation of borehole charges);

short-term temperature increase of air in zone of explosion of dust to 1000 - 1200 With;

shock air wave.

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