Salkova Anna

Institute of Mining and Geology

Speciality: Safety of labour activity

Theme of master's work:

Researsh of a condition and development of actions for decrease in a dust content of air, for prevention and localisation of explosions of a coal duct in the conditions of mine "Kurakhovskaya"

Scientific adviser: Stukalo Vitaliy

Actuality of the topic

     Prevention of coal-dust explosion is one of the most important problems of providing safe working conditions of miners in the mines which have dangerous explosively seams. If respiratory protection against dust and explosion is in poor condition, even local methane explosions coal dust occurring in any place of mine workings are capable of spreading over long distances. In recent years due to the intensification of coal mining by means of technical re-equipping of the coal industry and implementation of mining machinery of high productivity while having dramatically worsening mining-and-geological and mining-and-technical conditions one can see that dusting and gas formation in the coal mines increased dramatically, which led to high danger of explosion.

Objective and tasks of the work

     The objective of the work is to do the analysis of the measures on reduction of dust content in the air and prevention and localization of coal dust explosions in mine "Kurakhovskaya" and to work out the most effective measures on prevention and localization of coal dust explosions both in faces and in other places of mine workings.

Brief information about the mine

     The mine "Kurakhovskaya" forms a part of state enterprise "Selidovugol". Put into operation in 1940.

     Productive capacity is 400,000 tons a year. Annual plan for 2009 is 355 tons a year. At present the system of transport is being reconstructed. The mine is also preparing for increasing output of coal to 1000 ton a year. The main factors suppressing the increase of coal output are: conducting of the stope works at the considerable depth and on the suggestive distance from the main transport workings and airways; complexity of mine working ventilation, situated below level – 475 meters.

     Opening of the pit "Kurakhovskaja" has been made by tree sloping shafts, driven in the coal-bed l₂' and by two sloping shafts, driven in the coal-bed k₈ (southern part of the mine). Except the sloping workings the pit was opened by a vertical ventilation shaft and a prospecting shaft №1. A method of preparing of the pit is panel. The order of base service is descending. The bedding is flat. Coal seam isn’t disposed to spontaneous combustion. The system of extraction applied-long chimneys along bedding.

     The top possible depth of extraction in previous beds – 840 meters. Current depth – 320 m and 790 m.

     Total water inflow in mine is 800 m³/h.

     At present mining is being done in beds k₈ and l₂'. Stope works in mine are conducted with the help of mechanized complex КД-90. Preparatory workings are driven with the help of tunnel machine in КСП-21 and KSP-22. Wheeled and conveyer transport is used in the mine. Transport of men, load and materials is carried out by wheeled transport. Transport of rock from the 16th northern lava of bed K is carried out by conveyer SP-250; in site conveyer workings – СП 202, conveyor belt 1L-80; in all pit- by conveyor belts 1L-100, 1L-100Y, 1L-100K, 2LY-100, 3L-100Y, 2LY-120V.

     The mine "Kurakhovskaya" is not gassed, but it is dangerous because of coal dust explosion and carbon dioxide isolation.

Analysis of effectiveness of the present measures on dust content reduction, prevention and localization of coal dust explosions.

     Mine "Kurakhovskaya" state enterprise "Selidovugol" is described as being dangerous as far as coal dust explosions are concerned. The mine is mining seams К₈- l₂'.

     In order to reduce dust content in the air and prevent coal dust explosion there are following measures used in the mine:

     - roadstone dusting;

     - sprinkling in all the places of dust formation in working faces and development ones, in all the loading points and unloading ones;

     - dust wet cleaning;

     -use of mist-irrigation systems;

     - washing of mine workings.

     According to the certificates of 14 northern belt road of seam l₂' and 14 northern ventilating entry of seam l₂' they have taken measures on dust formation reduction and protecting the mine workings from coal dust explosions. The measures taken are as follows:

     a) sprinkling in all the places of dust formation in working faces and development ones, in all the loading points and unloading ones.

     Sprinkling while cutting loading machine 1K101У is working is done by spraying device ТОС-100, which is supplied together with the cutting loading machine. The system ТОС-100 consists of: water tank =0,5-1,5, filter ФШ-1М, dosimeter of wetting agent ДСУ-4, mine working water pipe-line ВЗ-32.

     On the screw conveyer and body of the cutting loading machine atomizers ПФ-1,6 and КФ-2,2 according to the standards “Norms of exploitation of cutting loading machine 1К101У”. Dust control while having blasting workings alongside with prevention of coal dust explosion aims at dust formation reduction and dust cloud elimination in the face space in order to prevent from its spreading over mine workings.

     In order to reduce dust formation and extinguish fire while having blasting workings they use hydraulic tamping with the help of polyethylene ampoules filed with water. Before starting blasting workings in the holes which adjoin working face they carry out sprinkling of the face and 20 m of the adjoining workings with water adding wetting agent and also they spray the loosened coal, rock with a hand-held water blast РО-1, which is connected to the fire-extinguishing and irriguous flight with a flexible hose with diameter of 25 mm.

     b) dust control while making development workings with water stemming, wetting of the loosened coal before it is loaded onto the conveyer belt;

     c) use of water curtains while having drilling and blasting operations using plastic bags filled with water and for their blasting ‘Yhlenit” 13P;

     d) dust control while coal transporting ;

     All the places of coal unloading from the conveyer belt are sprayed with a hand-held spraying-device.

     e) stone dusting;

     f) washing the adhering dust with water.

Table 1 Initial data and results of calculation of inert dust consumption for stone-dust barrier

Name of the working	Midsection of the working, m²	Number of barriers	Length of the working, m	Inert dust consumption per 1 barrier	Inert dust consumption per 1 of the working
Main loading stem pl. I2'	8,4	5	1 972	3 360	16 800
1 main loading stem pl. I2'	9,2	1	1 192	4 048	4 048
Transport working – 203 m	8,3	2	740	3 320	6 640
Warehouse	8,3	2	60	3 320	6 640
11 northern hauling road pl. I2'	7,4	4	1 550	3 256	13 024
14 southern belt road pl. I2'	8,6	3	850	3 784	11 352
14 northern belt road pl. I2'	9,5	3	1 200	4 180	12 540
14 northern air gate pl. I2'	9,6	3	1 200	4 224	12 672
Total					83 716

     While analyzing the data of the tables one can see that there are violations of Safety regulations as stone-dust barriers are placed at a bigger distance than it is required (300 m). Stone-dust barriers should be placed at the distance of not more than 300 m in conveyer workings and on 14 northern conveyer seam stone dust barriers should be placed at the distance of 400 m, in transport working of horizon -203 m stone dust barriers should be put at the distance of 370 m from each other. In hauling roads and air gates the stone–dust barriers should be placed at the distance of 300 m but on 14 northern air gate of seam l₂' they are placed at the distance of 400 m, which is a rude violation of Safety rules.

     At present there are 21 stone-dust barriers in use in the mine with total quantity of inert dust of 83,7 t. For the workings that require roadstone dusting the necessary quantity of inert dust in stone-dust barrier is 49,8 t. The mine, after changing the inert dust in the stone-dust barriers, uses the same dust for roadsone dusting, which is a rude violation of the norms of Safety rules. Inert dust after being taken from stone-dust barriers is unusable for roadstone dusting as it is wet and it cannot change to suspended state for making unexplosive mixture with coal dust.

Animated image of chart of mechanical oslancevatelya OMK-1 (3 shots, 3 reiterations, 115 Kb) 1 - swinging dispersive nozzle 2 - bunker 3 - ventilato 4 - plesmisitel [1]

     The mine also uses stone-dust and water barriers using plastic seamless cylinders (PSC) for localization of possible coal-dust explosions in the driving blind drifts.

     Dust wet cleaning is the same washing of the workings, although the cleaning of the congested dust coal and the dust from the soil of the workings is done as well.

     Mist-irrigation systems are also used, they reduce dust content of air. The mine uses two mist-irrigation systems at northern air gate 14 of southern long face of the seam l₂' and air gate 16 of northern long face of seam К₈. The use of mist-irrigating systems is very effective one especially for ventilation workings with high intensity of dust formation. The given method is based on the interaction of the processes of moisture accumulation on the surface of the working as a result of impactions of mist particles on the one hand and moisture evaporation from the surface of the working due to heat transfer from the other hand.

Perfection of measures on dust content reduction, prevention and localization of coal dust explosions.

     Some of the most effective means of explosion localization are automatic means of localization of coal dust explosions, which are not in use in mines. I think that they should be used as they are the most effective ones. They can localize dust explosion right at the spot in its initial stage. Automatic devices, unlike passive barriers, are supplied with an independent on external conditions source of energy, which is needed for constrained dispersion and supply of explosion suppression substance to the zone of explosion upon detector element signal, the substance should react to a physical phenomenon which accompanies the explosion. Such devices are functional systems which go off by a potential source of combustion when there is an explosion. Fire extinguishing is carried out with much less (in comparison to passive barriers) quantity of extinguishing material. There are of a rather small size and weight, which makes them rather easily movable along workings while mining. In addition the essential condition for successful fire extinguishing with an automatic barrier is placement of detector element and explosion suppression substance at some distance from each other, which is determined by inertance of the detector element, and the time of formation and existence of explosion suppression medium. [1]

     Automatic barriers are more rational ones as far as fire extinguishing can be carried out with much smaller quantity of extinguishing material.

     In order to prevent coal dust explosion besides the measures which are used by mines one can use washing not only with water but also with adding moistening and fixing compositions. The research carried out by MakSRI on non-toxic and rather common absorbers showed that the best of them are chlorides of zinc, calcium and magnesium. However, it will be most rationally to use calcium chloride as it is the cheapest one and the least corrosivity active one. Also, for explosion prevention it will be effective to use inhibitory substances, which can stop combustion reaction as well. Solid inhibitory substances are more preferable ones. Salts of alkaline metals belong to them. [2]

Conclusion

     The work analyzed the measures on reduction of dust content of air, prevention and localization of coal dust explosions which happen in mine "Kurakhovskaya" state enterprise "Selidovugol". Some violations of location of stone-dust barriers in mine workings. Some more effective measures on prevention and localization of coal dust explosions for the present and perspective period were suggested:

     a) the use of automatic means of localization of coal dust explosion at the sites of intensive dust congestion;

     b) the use of washing adding moistening and fixing compositions;

     c) the use of inhibitory substances.

Literature

1. Нецепляев М.И., Любимова А.И., Петрухин П.М., Плоскоголовый Е.П., Сургай Н.С., Борьба со взрывами угольной пыли в шахтах. – М.: «Недра», 1992, – 299 с.

2. Умнов А.Е., Голик А.С., Палеев Д.Ю., Шевцов Н.Р., Предупреждение и локализация взрывов в подземных условиях. – М.: «Недра», 1990. – 286 с.

3. Ищук И.Г., Поздняков Г.А., Средства комплексного обеспыливания горных предприятий. – М.: «Недра», 1990. – 253 с.

4. Нормативно-правовий акт охорони праці НПАОП 10.0-1.01-05 Правила безпеки у вугільних шахтах. – Е.: 2005, – 398 с.

5. Керівний нормативний документ. Збірник інструкцій до Правил безпеки у вугільних шахтах. – К.: 2003, Т1 – 479 с.

6. Марин С.В. Планирование развития горных работ при доработки запасов угля пласта k₈ ГП «Селидовуголь» ОП «Кураховская» [Электронный ресурс] / Портал магистров ДонНТУ, http://www.masters.donntu.ru/2008/fgtu/marin/diss/index.htm

7. Нормативный документ. Инструкция по предупреждению и локализации взрывов угольной пыли. – К.: 1998, – 554 с.

© DonNTU 2010 Sal'kova Anna

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