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Abstract

Contents

Introduction and rationale actuality topic

On the territory of Donbass has produced more than 200 years underground coal mining. Mine complexes alter drastically the natural landscape. In the coal mining and coal-processing plants, along with the production of primary products (coal, coal concentrate), a large number of gaseous, solid and liquid wastes (coal mine methane, rock, tailings, waste water). These wastes adversely affect the results of the economic activities of enterprises, because they require the costs of collection, transportation, storage, and also complicate the environmental situation in areas where mines[ 1].

Breed, stockpiled in dumps have different geochemical properties and particle size distribution, which is a consequence of the production technology, properties and thickness of the developed processes that occur with the rock on the earth's surface. The mineral composition of rocks [2], forming heaps of coal mines is closely related to their origin and subsequent effects of weathering and thermal effects, leading to its change, the depth of which depends on the genetic age heaps. Uglevmeschayuschie rock stockpiled in dumps are exposed to the thermal field, which leads to the formation of different types of rock dump coal mines. In connection with this distinction, and termoizmenennye termoneizmenennye dumping rocks.

As a result of complex exothermic reactions in the body of the blade, there is a spontaneous combustion of rocks and their constituent. Burning dumps continues for several years. This leads to air pollution by combustion products and their deposition on the surface [3]. In the emitted aerosols, particles which are carbon black, coke, silica beads, crystals of gypsum and organic residues. In the gas phase is dominated by sulfur dioxide and nitrogen oxides. As a result, the emission of acrid smoke from burning dumps very often on the territories adjacent to them is able to. During the year, on the breed heaps fall precipitation, which, filtering through the body of the blade significantly change their chemical composition. They are enriched with soluble compounds and form a man-made geochemical flows.

Despite the rapid development in recent years of forecasting methods and technologies for prevention of spontaneous combustion of coal and rock, remains an urgent task to improve the arsenal of means and ways to prevent endogenous fires in piles of mines and preparation plants. Despite the urgency of the issue and a long history of its study, the theoretical side, many have not been worked out in full

At present there is no consensus about the nature of self-ignition of sedimentary rocks. Many experts believe that the cause of spontaneous combustion of rock is their interaction with the oxygen of air. There are also a number of other assumptions, and attempts to explain the nature of the spontaneous combustion of solid fuels (decomposition of pyrite in the coal hypothesis as a result of the exothermic reaction of iron disulfide, with the participation of moisture and oxygen, ignite at normal temperatures produced by leaching of pyrite pyrophoric iron, the action of thiobacilli and others), but they have no conclusive studies and are only subject of scientific debate.

According to practice, usually ignites spontaneously wet rocks with weak aeration of the surface. The centers of self-heating of rocks are often found in secretions of iron sulphate and sulfuric acid. The formation of these substances, of course, is possible only when the oxidative leaching of pyrite contained in the rocks [4].

A more difficult situation with the practical implementation of fire prevention. Ideally, the procedure for the formation of dumps and preventive measures should prevent a fire. However, the desire to save money on preventive measures leads to a lack of proper attention to the problem of the producers. Moreover, even caused fires in some cases, allowed to drift, and the fire begins only under pressure from environmental authorities and bodies that control the production safety.

Speaking of burning waste dumps, you should consider the nature of the flow and combustion processes in an array of blade, which directly affects the measures to prevent and combat this phenomenon.

In connection with the investigation to establish the regularities of formation of foci of self-heating and spontaneous combustion rock dumps at the mines and concentration plants and development based on these methods of preventing and extinguishing pockets of spontaneous combustion in the waste dumps are the relevant scientific and technical task that will improve the ecological situation in the Kalinin region Donetsk by reducing the harmful effects of waste dump OP Mine it. Kalinina on the environment [5].

Objectives and tasks of the study

The aim is to develop and study engineering solutions to improve the environmental situation in the Kalinin district of Donetsk by reducing the harmful effects of OP waste dump, Mine it. Kalinina on the environment by fighting pockets of spontaneous combustion in the waste dumps, followed by its re-formation

To achieve this goal required the following tasks:

  1. To assess the influence of OP Mine it. Kalininaon the environment.
  2. Analyze the existing methods of preventing and extinguishing hotbeds of rock autoignition.
  3. Select and justify the suppression of blade technology OP Mine it. Kalinin.
  4. Select blade technology reshape OP Mine it. Kalinin.

The proposed scientific novelty

As a result, studies the mechanism of formation of foci of spontaneous combustion in the waste dumps has been further developed and was complemented by the stage of volcanic processes that formed the basis for developing methods of preventing and extinguishing pockets of spontaneous combustion in the waste dumps.

Practical value of the work

The elimination of foci of spontaneous combustion of waste dumps at the OP Mine it. Kalinin will make its re-formation, thereby improve the environmental situation in the Kalinin region of Donetsk, will release land for building in the city center.

Current and planned results by topic

Beaten off by an array of rock mass under the influence of gravitational forces and the impact of working machines and mixed into a medium with random orientation of the pieces. In this case, the emptiness of the surface layer is determined by the size of the mass of moldboard mezhkuskovogo space. Although the filter in such an environment can be substantial, it is the place where the distance between the walls of cracks does not exceed Δ =10-7... 10-8 m is of the free run of the gas molecules (γ)[6]. The air in these microcracks is in a state of vacuum, and the migration of gases occurs as a result of volcanic processes, ie processes of the expiration of a dilute gas of holes, the characteristic dimensions are less than the mean free path of molecules. The phenomenon of effusion allows complete understanding of nucleation centers of self-heating in the bulk rock dumps.

The equilibrium condition of a rarefied gas (pic.1) is significantly different from similar conditions is not a rarefied gas:

The formula for the conditions of a rarefied gas

where: P1 and P2 – the gas pressure in the first and second parts of the vessel, respectively, Pa.

The scheme of the vessel with the rarefied gas

Picture 1 – The scheme of the vessel with the rarefied gas

One consequence of is that if the pressure P1 and P2 were originally equal, due to effusion of gas begins to flow from the region of lower temperature in the region with the higher. This phenomenon is called thermal effusion.

The surface temperature of waste dump during the day varies under the influence of solar radiation, wind, precipitation, and at the same time at a certain depth the temperature remains practically constant (tc). In spring and autumn daytime temperatures are usually higher than the values of tc, the night – below. This leads to the pulsations of the air in the surface layer of crushed rock, provides a flow of air into the blade during the night and day release.

Consider the example of non-isothermal gas flow in the channel. If the two chambers, which are, respectively, at T1 and T2, connect a long cylindrical channel and fill the system with a rarefied gas, the camera will set the pressure P1 and P2, satisfying

The formula of pressure in the chamber

where γ depends on the Knudsen number in the channel and the factors of interaction of gas molecules with the surface of the channel γ takes values in the range from 0 to ½. Experimental data for He and Ar are presented in pic. 2. This effect was first studied by Knudsen in the hole and is known as the effect of Thermomolecular pressure difference, or Knudsen effect.

Experimental dependence of the γ for long channel on the degree of rarefaction of the gas molecules and the nature of

Picture 2 – Experimental dependence of the γ for long channel on the degree of rarefaction of the gas molecules and the nature of(the solid curve – theory for completely diffuse reflection of molecules).

Experiments show that the effect Thermomolecular pressure difference in long channels, as in the case of holes, the most significant in the regime of free-diameter channel, however, in contrast to the hole, the effect – in long channels is strongly dependent on the properties of the gas. Then it can be argued that when the equilibrium in a system filled with a mixture of gases, will enrich the latter one of the components.

The phenomenon of thermal effusion is typical of cracks in the vicinity of the contour of the blade when the ambient temperature is lower than the temperature at a depth of waste dump, so that there is an intensive air-filled micro-cracks [2].

Animation. Scheme of air movement at the macro-and microcracks. 5 personnel, 7 cycles, 35,5 kb, 1,45 delay

Picture 3 – Scheme of air movement at the macro-and microcracks.

Due to the heat of the effusion air penetrates into the cracks much more quickly than under the classical (Poiseuille) and turbulent diffusion. This further leads to a pressure differential in the macrocrack and the flow of air from the outside (for the undischarged balance of gases occurs with equal pressure on both sides of the vessel) [7].

In the presence of long channels by Thermomolecular pressure difference may also be enriched gas mixture from one of its components. Effect of thermal effusion is one of the most important factors that accelerate the formation of PAHO in the fractured medium [3].

Originating thus gas exchange contributes to the enrichment of oxygen mezhkuskovogo space and remove it from the gaseous products of physical and chemical processes that lead to self-heating of rocks, and further contributes to spontaneous combustion moldboard mass.

Thus, the effectiveness of ways to prevent endogenous fires in piles of mines and preparation plants can be increased by inhibition of volcanic processes, so that access of oxygen to ugleporodnoy mass will be limited.

Summary and conclusions

As a result of the master's work received a theoretical basis and practical solution to current scientific and technological task of improving the environmental situation in the Kalinin district of Donetsk by reducing the harmful effects of OP waste dump, OP Mine it. Kalininaon the environment by fighting pockets of spontaneous combustion in the waste dumps, followed by its re-formation.

The main scientific and practical results are the following:

  1. The mechanism of formation of foci of spontaneous combustion in the waste dumps has been further developed and was complemented by the stage of volcanic processes that formed the basis for developing methods of preventing and extinguishing pockets of spontaneous combustion in the waste dumps.
  2. A new way to prevent the occurrence of lesions on the spontaneous combustion of waste dumps on the basis of antipirogennoy mixture that can provide safe and effective prevention of endogenous fires due to the continuous and long-term release of gaseous inhibitors as a result of electrolysis..
  3. The technology reformation of waste dump OP Mine it. Kalinin.
  4. As a result of the proposed measures will improve the environmental situation in the Kalinin district of Donetsk by reducing the harmful effects of OP waste dump, Mine it. Kalininaon the environment, thereby reducing morbidity and provide some economic benefit (exemption of areas in the city center

List of sources

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  2. Костенко В.К. Особенности динамики газов в разрушенных горных породах/ В.К. Костенко, Е.Л. Завьялова // 10-я сессия Междунар. бюро по горной теплофизике, 14-18 февр. 2005г.: сб. докладов. – Гливице, 2005 – С. 43-50.
  3. Предупреждение и тушение подземных эндогеннх пожаров в труднодоступных местах/ [Костенко В.К., Булгаков Ю.Ф., Подкопаев С.В., Завьялова Е.Л., Костенко Т.В. и др.]; под общ. ред. В.К. Костенко. – Донецк: Изд-во «Ноулидж» (донецкое отделение), 2010. – 253 с.
  4. Уголь Украины №8. Использование пород шахтных отвалов , – 1972, – с. 51.
  5. Янов Н.К. Использование промышленных отходов в строительстве. Киев: Будівельник, 1982. – 60 с.
  6. Звягинцев Г.Л. Промышленная экология и технология утилизации отходов. – Харьков: Вища школа, изд. при ХПИ,1986. – 232с.
  7. Янов Н.К., Гавриш В.И. Разработка шахтных терриконов. Донецк, «Донбасс», 1972.