The hottest new technology for dust control in for

Song Majun, a new technology for dust control in foreign coal mines, can produce a large amount of dust in the production and operation process of coal mines, such as machine mining, fully mechanized mining, blasting mining, stoping, bolting and shotcreting, shipping, coal preparation and other processes. Workers work in an environment with high coal dust concentration for a long time, and breathing coal dust can cause pneumoconiosis, which seriously endangers the health of coal miners. Therefore, effective measures must be taken to control it

I. Introduction to foreign coal dust control technology

in foreign countries, the following technical control measures are mainly taken to reduce the degree of coal dust pollution

1. coal seam water injection

coal seam water injection is to use the pressure of water to inject water into the mined coal seam through drilling holes, so that the coal body can be pre wetted, so as to reduce the production of floating coal dust during coal mining. This measure has a good dust reduction effect, which can generally reduce the dust concentration by about 60% - 90%. Long borehole water injection method has the advantages of uniform wetting of coal body and large wetting range, and it is preferred as the main water injection method at home and abroad. The number of working faces using water injection to reduce dust in foreign countries accounts for a high percentage of the total number of working faces, while the number of working faces using coal seam water injection in China is relatively low. This gap is not caused by water injection technology or equipment, but by lax management of dust control and ineffective promotion of effective water injection technology measures. Some countries humidify coal seam water injection. If conditions permit, emollients or calcium chloride (2) admixtures improve the degree of wetting and the effect of dust reduction. The former Soviet Union has developed an instrument for measuring the moisture of coal seams before and after water injection

2. Spray dust reduction

spray dust reduction is to spray water mist on the dust floating in the air, and achieve the purpose of dust reduction by increasing the weight of dust particles. The key of this technology is that the nozzle should be able to form a fog flow with good dust reduction effect. Some countries have developed a series of nozzles. The United States, the former Soviet Union and other countries have also conducted a lot of research on determining fog flow parameters, and established nozzle inspection centers to ensure the production quality and use effect of nozzles

3. Use the dust collector to remove dust

use the dust collector to separate the dust in the air, so as to achieve the purpose of purifying the air content. At present, dust collectors are widely used in coal mines in some major coal producing countries abroad. The United States has adopted dust removal fans, wet fiber dust collectors, small cyclone dust collectors and other equipment. Wet washing dust remover and wet filter dust remover are used in roadways and roadheader in Britain. The former Soviet Union used wet cyclone dust collectors and vacuum pumps in roadheader, shearer or steep coal seam, return air roadway, etc. In Germany, dry bag filters are used at crushers, transfer points and roadheader. Foreign dust removal equipment is generally large and bulky, but it has high dust removal efficiency, good noise elimination effect and large air volume for treating pollution

4. Foam dust removal

the effect of foam dust removal is good, which can generally reach more than 90%, especially for respiratory dust below 5mm, the dust removal rate can reach more than 80%. Compared with spray sprinkling for dust removal, the water consumption of foam dust removal is reduced by more than 1/2. Since the dust removal technology came out in the 1950s, some major coal producing countries such as the United States, the former Soviet Union, Poland and so on have been widely used in production, and have developed finalized low-cost foaming agents that meet the safety, health and use requirements. According to the requirements of different dust sources, different types of foam dust removal supporting series equipment have been developed

II. Dust prevention measures for different operation positions

1. Dust prevention during roadheader operation

when the cantilever roadheader works in the roadway, it generally adopts an open dust removal system, and the main dust prevention measures are: spray watering, water and air ejector dust removal. Many foreign countries install the dust collector on the roadheader for dust removal, and some countries such as Germany and Austria install the dust collector 20~30m behind the roadheader. When the roadheader moves forward, the dust collector moves forward regularly. Generally speaking, when excavating a large cross-section roadway, the lagging movement of the dust collector is adopted. When the working face needs to deal with less polluted air volume, there are many ways to place the dust collector on the roadheader. Using these methods, the dust concentration of working flour can be reduced by about 90%

2. Dust prevention of drilling and blasting operation

a large amount of dust can be produced during drilling and blasting, and the dust concentration can reach more than 600mg/m3. Wet drilling and shooting are generally used at home and abroad. We dare to promise the quality of the experimental machine and take measures such as spray watering and water curtain purification, but the weight loss is small. In foreign countries, many countries adopt wet dust collectors, water and air ejectors and annular watering measures to purify the smoke and dust generated during blasting

3. Dust prevention of bolting and shotcreting support operation

in the bolting and shotcreting support operation, a large amount of dust can be generated, some as high as 600mg/m3 or more. At present, most foreign countries eliminate the production of dust by improving the anchor spraying process. Germany mainly adopts measures such as pneumatic automatic conveying, mechanical mixing and wet shotcreting to reduce the dust concentration during anchor shotcreting support operations, and has achieved good dust reduction results

4. Dust prevention of the mining face

in order to reduce the amount of dust produced by the mining face, in addition to the measures of pre wetting the media, the following dust prevention measures should be taken:

(1) select reasonable structural parameters and working parameters for the cutting structure of the shearer. Germany and Britain have conducted a lot of research on this, found out the relationship between the parameters, and controlled the dust production of coal dust

(2) set up a reasonable spray system on the shearer. Drum Shearers are generally equipped with internal and external spray, that is, spray water mist from the nozzle installed on the drum and spray water mist from the nozzle installed on the fixed box, rocker arm or baffle of the cutting part to reduce dust. The layout and quantity of nozzles, the type selection of nozzles, and reasonable nozzle parameters are closely related to the dust reduction effect. Foreign countries attach great importance to the nozzle system and dust reduction effect of shearers, and supply water in strict accordance with the requirements of spray parameters, so the dust reduction effect is generally good

(3) set up a reasonable spray system for the self moving hydraulic support. At present, some coal mines adopt the method of installing nozzles in the roof control area to reduce the high dust concentration generated during frame shifting. In foreign countries, some countries have realized the spray automatic control system to reduce dust when lowering the rack

(4) adopt the best dust removal wind speed and reasonable ventilation technology. The optimal wind speed increases with the increase of coal moisture, generally between 1.5~4m/s. Adopting downward ventilation can effectively reduce the dust concentration in the mining face

5. Dust prevention of blasting mining face

comprehensive measures such as wet coal body, wet drilling, blistering mud, washing coal wall, spray at transfer point and adopting the best dust removal wind speed must be adopted for dust prevention of blasting mining face, so as to reduce the dust concentration of the working face

6. Dust prevention during loading and transportation

in foreign countries, automatic spray sprinklers are generally installed on rock loaders, and automatic spray devices are installed at loading points to wet the coal in the coal sliding eyes with wetting pipes. Or use a closed cover or semi closed cover to seal the dust source, and draw the dusty air from the bottom to the dust collector for purification. In foreign countries, kangfuluo automatic spray sprinkler is generally used. Where the height of falling coal is high, a closed cover or dust collector is installed to remove dust, so as to achieve the purpose of purifying the air

7. Dust prevention during cage coal pouring operation

automatic spray watering measures are generally adopted in foreign countries to suppress the flying of coal dust. In addition, the dust producing point is completely sealed, and the dusty air is extracted from the lower part for purification treatment, so as to reduce the large amount of dust raised during cage turnover

III. personal protection measures

at present, foreign personal protection uses self-priming dust masks, filtered air supply dust masks, air flow helmets, etc. Due to its prominent focus and wide application, it has played a positive role in protecting the health of miners. The dust prevention efficiency of individual protective measures is high, which is one of the important technical measures to solve the problem of dust hazards in mines