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Abstract

Contents

1. Relevance. Purpose and objectives

The gas-dynamic phenomena problem (GDP) is the most complex and not completely solved problem in the coal industry.

Gas-dynamic phenomena especially sudden emissions of coal and gas can lead to loss of life and huge economic expenses. Coalmines are swamped with coal, mining equipment is put of action, the fastening is beaten out and deformed, collapse of breeds occurs and framings are filled with methane. It leads to the long stops of operations and connected with danger of explosion of a dust-gas compound in excavations. Elimination of coal and gas burst consequences has an adverse effect on technical and economic indices of mines operation.

May 24, 1999 – the explosion killed 50 people and injured 40 people.

August 19, 2001 – an explosion of gas-air mixture in combination with coal dust killed 55 people. There were 34 people injured, missing 10 people.

July 31, 2002 – the explosion killed 20 people, injured two people.

As a result of three bombings in November-December 2007, killing 106 people, 156 more miners were injured – this is the biggest accident in the history of Ukraine the number of victims: November 18, 2007 on the horizon in 1078 meters there was an explosion of methane-air mixture. According to the MOE, at the time of the accident there were 456 underground miners, including emergency stations – 186. The explosion killed 101 miners:

December 1, 2007 – as a result of the second explosion injured 52 miners, state 35 people – moderate, 9 – heavy.

December 2, 2007 – rescuers killed 5, injured another 66 were hospitalized.

With increasing depth the development of the threat of sudden coal and gas is significantly increased. It concerns the formation and l4, which is a mark of 400 m began to be threatened by sudden outbursts. Besides the need for coal are continuously increasing, which increases the load on the shaft [2].

Currently the mine AF Zasyadko mines develops four outburst mine formations m3, l1, l4 and k8. During these layers development on mine there were 15 sudden bursts of coal and 120 bursts in case of shaking detonation.

In this article, it is planned to research and justify possibility of application in preparatory framings of layer l4 normative method to prevent of sudden bursts of coal and gas – torpedoing of the coal massif without preliminary forcing of water in layer [1].

To achieve this goal in the article the following problems has been solved:

  1. The analysis of mining-and-geological and mining conditions of performing mining operations on mine during layer l4 development.
  2. The analysis of application of measures set is carried out in order to the prevent gas-dynamic phenomena during preparation of a pull-out site of l4 layer.
  3. 3. Theoretical and experimental bases of torpedoing the coal massif are studied.
  4. Parameters are proved and the technology of torpedoing of the coal massif in preparatory and clearing productions of layer is developed.
  5. The technical and economic assessment of the offered way of the coal massif torpedoing is performed.

2. Mining-geological and technical conditions of conducting mining operations and the set of measures applied when developing l4 layer according to the prevention of the gas-dynamic phenomena

Layer l4 Coking . Power 0,9–1,2m, structure difficult and simple, G-mark coal, low-ash (1,4–26,9), middle sulfurous (0,8–2,9), average stiffness, f=1,0–1,5, volume weight 1,31, resilience to cutting — 210/235kg/sm, the hade changes from 9 to 140, dangerous on gas, explosibility of coal dust, releases of methane, it isn't self-ignition prone, from level 400 ì it is dangerous on sudden emissions of coal and gas.

The direct roof of layer is put by soapstone and aleurolite.

The direct soil is presented by aleurolite, soapstone and in two points – sandstone.

L4 layer is developed under partial protection with use of the increased mountain pressure (IMP) in the unprotected zones.

During preparation of an extraction site carrying out preparatory developments on l4 layer takes place by shaking diving or the KSP-32 combine of the general face.

Carrying out a ventilating shtrek by the combine is carried out next to earlier fulfilled floor after finding a safe zone of unloaded layer on dynamics of initial speed of gas emission. Potentially dangerous zones are handeled with hydroloosening with control of way efficiency and gas emission loudspeakers.

Scheme of hydro loosening

Pictures 1 – Scheme of hydro loosening

Deploying a conveyor shtrek and assembly trip by the combine is carried out after hydroloosening and control of efficiency of hydroloosening on dynamics of gas emission or in parameters of an acoustic signal.

At hydroloosening inefficiency in dangerous zones development is carried out by shaking detonation on coal. Also advancing of a rock face before coal is not less than 0,5 m and no more than 2,5 m. The rest of rock is taken out by driving combine. Cleaning of the loosened coal is performed by hand. Alignment of a coalface with mechanical and manual tools is forbidden.

According to mine specialists a preliminary antiburst actions in preparatory of l4 layer is rather difficult and labor-consuming in performance, and above all because of frequent cases of a hydroloosening inefficiency is connected with need of transition to shaking detonation.

3. Theoretical and experimental bases of the coal massif torpedoing development

Theoretical basis of development of a way of torpedoing was the solution of a task about influences of various factors on a form and the sizes of a destruction zone of layer at explosion of a borehole charge in regional part of coal layer. During solution of a task coal layer was considered as elastic uniform isotropic. Function of detonation pressure in a well was considered as superposition of explosive impulses of consecutive set of elementary spherical charges (pic. 1). The basis for the solution of a task was the solution of movement equation of elastic medium for a spherical cavity with radius R0, which is evenly loaded with pressure P0 from an explosive impulse of a dot charge.

Driving to the formulation of the task

Pictures 2 – Driving to the formulation of the task

The scheme to a problem definition: 1 — free surface of layer; 2 — well; 3 — direction of charge initiation; 4 elementary spherical charge; σx(x), σy(x) and σz(x)— epyura of the main static tension; Lc and η0 respectively length of a well and face; Ç — current coordinate of an elementary charge; P0 — pressure in a spherical cavity with radius R0; γ — volume weight of overlying rock; H — depth from a earth surface.

By results of the task solution it is concluded that the free surface and tension of layer define a destruction zone form close to a cone what means that destruction of layer within the effective radius Ref is possible not on all length of a well but à only on site of so-called effective length of a well Lef.

Assessment of influence of various factors on the sizes of a zone of destruction and effective length of a well Lef it is reached by change of numerical values of indicators of intense deformed layer condition, operability of mine, lengths of a well and mine.

The main results of analytical research of explosion of a borehole charge in regional part of layer are used for definition of the main directions of mine works on development of parameters for torpedoing technology.

It is shown that in practice the integrated characteristic of the intense deformed condition of layer is the safe unloading zone of size lá, determined by dynamics of initial speed of gas emission.

4. Parameters and torpedoing technology

All key parameters of torpedoing technology (wells length, distance between wells, non-reducible advancing, etc.) and the defining reliability and efficiency of a method are established with use of experimental data on change of the intense deformed and dynamic condition of explosion layer of borehole charges.

Torpedoing is carried out in wells with a diameter of 55-60 mm. Length of wells lc is chosen depending on the lo layer unloading zone size and established on dynamics of gas emission (Table 1).

(Table 1)

Table 1

The size of non-reducible face is chosen as lno. Well length for the first cycle of torpedoing is set equal to 5m. For the subsequent cycles, it is calculated from following expression, taking into account a daily movement of a lday face:

Lno = lday + 1 ≥ 3 m.

The distance between trailer parts of wells in niches should not exceed 2m in combine part of lavas and preparatory developments — 2,5m. The wells located in the corners of a face have to go beyond a development contour not less than on 2 m.

The mass of a borehole charge determine by a formula

Q = q(lc − lç), kg,

Where q – mass of meter of a charge, km/m; lç – total length of a way (not less than 3 m with a length of well of 8,5 m, 4 m with a length of well of 8,5-10 m, and 5 m with a length of well more than 10 m.

Schemes of wells arrangement for torpedoing and control shots for a way efficiency control on dynamics of gas emission or in acoustic signal parameters

à) in a preparatory face ; á) and â) in the lower niche and combine part of a lava.

Layout diagram wells

Pictures 3 – Layout diagram wells.

Conclusion

Thus in this work was presented general characteristics of the mine, as well as a generalized theoretical information needed to calculate the parameters of hydroblasting in the mine named after AF Zasyadko..

References

  1. Terms mining in seams prone to gas-dynamic phenomena: Standard Coal Ministry of Ukraine – Ê.: 2005.
  2. Accidents at Mine named after A. Zasyadko "Electronic resource" —Mode of access: Accidents at Zasyadko coal mine.
  3. Yaylo Vladimir thesis. Research and development of ways to prevent coal and gas based on gidrovzryvanii. Â. – 1982.