Explosives commonly used in mines include: ammonium nitrate explosives, ammonium explosives, ammonium ladder explosives, slurry explosives, emulsified fried drugs, black powder, nitrified sweeteners, ammonium slag explosives, and the like.
I. Ammonium nitrate explosives
Ammonium nitrate explosives contain less TN and have less power and are suitable for use in open pit mines. Coal mine used ammonium nitrate explosive, its composition and properties and open pit is different.
Second, ammonium fry
The ammonium explosive is a non-sensitizer-containing explosive prepared by mixing ammonium nitrate and fuel oil (light diesel oil, heavy oil, engine oil, etc.) as a main raw material.
Third, the ammonium ladder explosive
Ammonium ladder explosive, the appearance is light yellow powder, the density of the medicine roll is generally 0.85-L10 g/cln3, the functional force is 240-350 MJ, the intensity is 8-13 mlil, and the detonation speed is 2400-5100 m/s.
4. Slurry explosives
The slurry explosive has a paste appearance, so it is called a slurry explosive. It is a mixed explosive containing an oxidizing agent aqueous solution, a sensitizer and a gelling agent as a basic component. Later, due to the use of a cross-linking agent and containing moisture, the original viscous paste became a strong viscous gel explosive, also known as a water-gel explosive. There is no strict distinction between the performance of water gel explosives and slurry explosives. Slurry explosives have the advantages of strong water resistance, good plasticity, high charge density, large explosive power, good safety and low cost. Therefore, open pit mines are widely used in water depth blasting.
Five, emulsified fried drugs
The appearance of the emulsified explosive is milky, and its performance is superior to that of the ammonium explosive. It has good water resistance and low cost, and is suitable for blasting of open water mine water working face.
Sixth, black powder
It is composed of potassium nitrate, charcoal and sulfur. Potassium nitrate is an oxidant; charcoal is a flammable agent; sulfur is both a flammable agent and a binder for charcoal and potassium nitrate, which is beneficial to the granulation of gunpowder. Black powder has high friction sensitivity and strong sensitivity to gunpowder. The explosion point is 290-310 Â°C, the explosion temperature is 238C, the detonation speed is 380-420 m/s, and the density is 1.60-1.93 g/cm3.
Seven, nitric acid fried medicine
The appearance of nitroglycerin is light yellow, translucent, elastic, not deformed after pressure, and has high sensitivity. After impact or friction, it will quickly exert its potential. Nitrifying sweeteners are toxic, causing severe headaches and heartbeats when human skin comes into contact with or contaminates with its vapor. Therefore, when using nitroglycerin, the operator should pay great attention to avoid harm to health.
The nitroglycerin is a sensitizer which is a sensitizer which combines liquid nitrate (nitroglycerin or nitroglycerin) with nitrocellulose, and is prepared by using wood powder, sodium nitrate or ammonium nitrate as adsorption materials. These explosives contain different amounts of ammonium nitrate and have different power levels.
Eight, ammonium leachate explosive
Ammonium leaching wax explosives are explosives prepared from ammonium nitrate, asphalt , paraffin, and wood flour.
Nine, the coal mine allows explosives
Coal mine underground blasting has stricter requirements on blasting materials. This is because most of China's coal mines contain biogas or coal dust. If improper use of explosive materials is used, it will cause gas explosion. According to the experimental determination, the concentration limit of biogas explosion is 4% to 15%, and the most explosive concentration is 9.5%. For example, the concentration of biogas is (9 soil 0.3%% <determining the standard concentration of explosives), when the flame temperature is 650 Â°C, the duration is up to 10s gas to burn or explode; when the temperature is 1000 Â°C, it will explode in 0.1 s; the temperature is 2000. ~C, an instant explosion. The concentration of coal dust explosion, the lower limit is generally 45 g / m3, the upper limit is not uniform. When the concentration is 300-400 g/m3, the explosive power is the largest, and the detonation temperature is generally 600-1 000 Â°C.
Therefore, the source of fire and temperature are the main factors that cause gas and coal dust. The high temperature and high pressure gas generated after the explosion of explosives can easily detonate gas and coal dust. Therefore, different working conditions and different mine gas levels must use different explosives and detonating materials.
Introduction to the use of explosives in coal mines:
1. Coal mine ammonium ladder explosive
The ammonium ladder explosives produced in China are mainly composed of ammonium nitrate, TNT is a sensitizer, salt is a flame-retardant, and some anti-water agent or combustible agent is added. The power is small and it has certain safety to gas coal dust. .
2. Coal mine water gel explosive
Coal mine water-gel explosives are water-based explosives with methylamine nitrate as the main sensitizer. A gelled explosive prepared by dissolving a material such as methylamine nitrate, an oxidizing agent, a combustible agent, a density adjusting agent, and a flame-damping agent in an aqueous solution having a gelling agent and chemically crosslinking. Its appearance is gelatinous and elastic, and it has the characteristics of large function, good water resistance, safe transportation and use, and less toxic gas.
3. Coal mine emulsion fried medicine
The emulsified explosive is an emulsification effect of an emulsifier, so that the originally incompatible oil-water two substances form a miscible mixture in the presence of a large amount of inorganic salts. This mixture is a water-in-oil type latex. Wherein water is a dispersed phase (internal phase or aqueous phase), an oxidizing agent (ammonium nitrate, sodium nitrate, sodium perchlorate, etc.) is dissolved therein, and a continuous phase (external phase or oil phase) is composed of a carbonaceous fuel such as paraffin or diesel. And so on.
According to the safety of gas, coal mine emulsion explosives are divided into 5 grades, and the current production is mainly 2, 3, and 4 grades. Level 2 applies to high gas mines; Level 3 applies to coal and gas outburst mines; Level 4 applies to mines with the most dangerous coal and gas outbursts. When selecting, it should be strictly selected according to the concentration of coal mine gas, and should not be mixed.
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