Explosion conditions and preventive measures of th

2022-08-04
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Explosion conditions and preventive measures for sulfide mineral dust

when the dust of many substances is dispersed in the air in a suspended state and has a certain concentration, it will burn or explode under the action of certain heat energy. Different substances have different explosion ranges, which sets a motto for themselves. The dust explosion is not only related to the concentration, but also related to the oxygen content in the air, the moisture content of the dust, the particle size of the dust and the detonation energy

sulfide ore contains combustible sulfur, which is explosive when the sulfur content in mineral dust reaches a certain value. The generation of mineral dust is mainly drilling, ore drawing and blasting. When fire detonators are used for blasting or sectional initiation, the first initiated explosive explosion may cause mineral dust explosion by providing heat source

the conditions for sulfide mineral dust explosion are:

(1) the content of mineral dust is higher than 40%

(2) the moisture content of mineral dust is less than 5%

(3) mineral dust concentration: Pyrite 0.39g/l; Pyrrhotite 0.425g/L; Chalcopyrite 0.505g/L; Sulfur 35g/l

(4) there is enough detonation energy. For example, in a 0.83m3 iron box, the amount of explosive used to detonate sulfide dust should be greater than 5g

method for distinguishing sulfide dust explosion:

during blasting, the photographic film is made into a flag and fixed on the roadway wall at a certain distance (5 ~ 20m) from the working face. Once the mineral dust explodes, the film will be burned to judge where sulfide dust explosion has occurred; Or measure the air temperature within 7 ~ 10m from the working face with the help of high-temperature thermistor. If the temperature is 100 ~ 700 ℃, it can be determined that mineral dust explosion has occurred

measures to prevent sulfide dust explosion:

(1) do not use fire detonators for blasting, use electric detonators for blasting, and try to use low-level millisecond detonators

(2) coat a layer of inert material (such as silica gel) with large heat capacity (specific heat) on the charge. By 2020, the utilization ratio of degradable green packaging materials will reach 50%, or use water or inert material as filling, so that a large amount of heat can be absorbed during blasting to avoid a sharp rise in temperature after blasting

(3) use explosives with very low limit temperature, such as coal mine safety explosives

(4) strengthen ventilation and spray watering to dilute and humidify mineral dust, reduce explosion and more accurately explain the explosion risk

(5) reverse initiation is not adopted. Reverse initiation is easy to cause explosion pressure and flame concentration, and it will be ejected through the blast hole to detonate sulfide mineral dust. Some tests show that gas explosion will be caused by reverse initiation when the charge is small. However, under the same conditions, even if the charge is much larger (several times more), it will not cause gas explosion. Some national coal mine safety regulations clearly stipulate that the reverse initiation is not allowed in the working face with the danger of gas and coal dust explosion. China's Ministry of coal has also had similar provisions

(6) strengthen the blasting hole plugging. The test data show that the amount of charge for detonating the mineral dust by plugging the blasting mud is much more than that by detonating the mineral dust without plugging the blasting mud. It is very dangerous to block the blast hole without blocking, less blocking or using explosive wrapping paper as gun mud. Unloading and non filling blasting in the strengthening stage shall be prohibited in places with explosion risk of sulfide mineral dust

(7) deep hole blasting shall be adopted as far as possible, and shallow hole blasting and soil covering blasting shall not be used

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