(1) Dust-proof measures

The role of dust prevention measures is to reduce the generation and flying of coal dust under the well.

1. Dustproof when drilling

(1) Wet rock drilling. The essence of wet rock drilling is to continuously send water to the bottom of the borehole as the rock drilling process is carried out to flush the cuttings and moist rock powder to reduce the generation and flying of rock dust.

(2) Water drills and drills. The water electric drill is mainly used in the mining and coal roadway driving face, and can also be used in the soft rock and semi-coal rock driving face.

(3) Dry dust collection. Dry dust collection is mainly used in rocky roadway driving face under water shortage, high cold area and some special conditions.

2. Dustproof when shooting

(1) The water bag is filled with blastholes. Commonly known as "water cannon mud." The essence is to fill the plastic bag filled with water in the blasthole, the water bag is blasted when blasting, and the water is pressed into the crack and atomization of the coal to achieve the purpose of dust prevention.

(2) Water seal blasting. Water-sealed blasting can not only reduce the amount of coal dust generated, but also reduce gas emission, increase the safety of blasting and improve the blasting effect.

The practice of water seal blasting is: after the explosive is installed in the blasthole, the orifice is sealed, and then the water is injected into the blasthole and then blasted. The blasting method can be used for coal roadway excavation or for mining.

(3) Spray. Spray is a simple and easy way to reduce dust during blasting. Most of the sprayers are combined with wind and water. With the pressure of the wind as the main power, the water below the wind pressure of 98kPa ~ 196kPa is sprayed out to make it atomize. It has a large range, fine mist, wide spray surface and good dust-reducing effect.

(4) Water curtain. Water curtain is also an effective measure to reduce dust and smoke when the working face is shot. At the same time, the water curtain is also located in the return air passage of the coal mining face or the roadway rich in dust source to reduce dust and purify the wind.

3. Dustproof when installing rock (coal)

After blasting or coal mining face blasting, it is common to first flush the coal gang and rock gang with water to remove the deposited dust, then sprinkle the coal pile or rock pile and finally ship it.

(1) Artificial watering. The general requirement is to fully wet the blasted coal or rock, not only to sprinkle water before shipment, but also to sprinkle water frequently as the shipment progresses, thus reducing the dust concentration to around 2 mg/m3.

(2) Sprayer sprinkler.

4. Dustproof during transportation

The main measure is spray watering.

5. Dust prevention when mining machinery cuts coal

(1) Select the best cutting speed. The cutting parameters of mining machinery have a great influence on the amount of dust generated. Generally, measures such as reducing the number of teeth, increasing the pitch, increasing the depth of cut, and reducing the cutting speed are taken.

(2) Spray watering. Spray watering is a dust reduction measure commonly used in mining machinery to cut coal. There are external spray sprinklers and internal spray sprinklers, which can also be used together.

(3) Dust removal measures:

1 Dust collector dust removal.

2 gun dust removal. Foam dedusting is carried out by mixing a surface active blowing agent with water and spraying it into a coal mining area of ​​a mining machine through a foaming device and a conduit to capture coal dust. Because the generated foam is very bulky, it covers the dust source and achieves the purpose of preventing dust from flying.

3 ventilation and dust removal. Reasonable ventilation measures can effectively eliminate dust, which is one of the dust-proof means of mechanized working face. The dust removal effect of the tunneling ventilation is closely related to the ventilation method. Press-in ventilation allows for faster cleaning of the working surface space, but dusty air passes through the entire roadway. Withdrawable ventilation, the dust removal effect is significant only when the air inlet of the air duct is no more than 2m away from the working surface. Therefore, the mixed ventilation and dust removal effect is the best.

6. Pre-wet coal body dustproof

The pre-wet coal is wetted with water before the coal has been mined, increasing the moisture of the coal to reduce the amount of coal dust generated during mining. The method includes coal seam water injection and watering in the goaf.

7. Personal protection measures

Because the breathable dust in the coal mine is very harmful to the miners. Therefore, personal protection should be highly valued. Commonly used personal protectors have:

(1) Self-priming dust mask. The self-priming dust mask is purified by inhaling the lungs of the human body to filter the dusty air through the filter material of the mask. It is divided into two types of ventilation valves and ventilation valves.

(2) Air supply type dust mask. The air-discharge dust mask uses a micro-ventilator to send dusty air to the filter material for purification. The purified air is then sent to the mask through a serpentine tube for breathing.

(3) Compressed breathing apparatus. The compressed air respirator is an isolated personal protective device. It is the compressed air in the downhole compressed air pipeline after filtering, disinfecting and decompressing, and then passing through the conduit into the population cover for breathing. The advantage is that it eliminates the danger of dust and is comfortable to breathe. The disadvantage is that the working place needs to have a pressure air duct, and each person drags a long pipe, which is inconvenient to move.

(2) Explosion-proof measures

Measures to prevent coal dust generation and prevent coal dust from igniting are called explosion-proof measures.

1. Cleaning the deposited coal dust

The deposited coal dust accumulated around the roadway, brackets and equipment should be cleaned regularly. Most of the coal mines in China are manually cleaned, and then cleaned after watering to prevent coal dust from flying, and the cleaned coal dust must be transported away.

2. Flushing deposited coal dust

Regularly flush the top of the roadway, the coal dust on the support and the support, and clean the coal dust.

3. Brushing

Brush the main roadway and the diverticulum. The brushing material is quicklime and water, and the volume ratio is 1:1.4, which is sprayed on the roadway gang or top by hand or mechanically. Its function is to easily observe the coal dust deposition in the roadway, and at the same time, it can cover and consolidate the deposited coal dust so that it is no longer flying.

4. Stuffed rock powder

Rock powder is an inert dust. It is used to spread rock powder around the roadway, which can increase the incombustible substances in the deposited coal dust, and can prevent and control the coal dust explosion. However, the explosion-proof effect of rock powder can only be effectively exerted when it reaches a certain proportion in coal dust. As the amount of coal dust generated and the strength of coal dust deposition increase, it is necessary to repeat the cloth frequently.

5. Bonding deposited coal dust

Bonding and depositing coal dust is to spray the bonding liquid around the roadway. The binder is mainly composed of a wetting agent and an inhalation salt, which can bond the deposited and successively deposited coal dust to lose its flying ability and prevent it from participating in the explosion.

(3) Explosion-proof measures

Measures to limit the extent of coal dust explosion accidents and not to spread them are called explosion-proof measures. There are two types of explosion-proof measures:

Rock meal shed

The rock powder is placed on the rock powder shed and placed in the roadway. When the coal dust explosion, the shock wave blows over the rock powder shed, causing the rock powder to fly, forming a thick cloud of rock powder and intercepting the explosion flame to prevent the spread of the explosion.

In the two wings of the mine, adjacent mining areas and adjacent coal seams must be separated by rock powder sheds. When the rock powder is not easy to fly, it needs to be replaced. The coal dust that falls into it should be checked and removed frequently.

2. Water shed

In recent years, water sheds have been used instead of rock sheds to isolate coal dust explosions. The water shed is composed of a water tank. Similar to the rock powder shed, the explosion shock wave causes the water shed to be turned over or broken, and the water is sprinkled on the roadway space in an instant to form a water mist to prevent the explosion flame from spreading.

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