RU1803559C - Method of mining thin and medium-thick seams of mineral resource out of protective pillars under water objects - Google Patents

Abstract

Usage: in underground mining of reservoirs to reduce mineral losses in safety pillars and to ensure the safety of operations during mining of the reservoir under water bodies. SUMMARY OF THE INVENTION: Before the start of treatment works from the preparatory workings, the rocks are softened over the formation in the range from three to ten times the removable capacity of the formation, counting from the roof of the latter.

Description

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The invention relates to the mining industry and can be used to develop single mineral formations of thin and medium power within protective pillars under water bodies.

The purpose of the invention is to reduce the loss of minerals in the safety pillars and to ensure the safety of mining operations under water bodies.

This goal is achieved by preliminarily softening the rocks from threaded workings ranging from three to ten times the removable thickness of the formation, counting from the roof of the latter.

A distinctive feature of the proposed method is as follows.

In the prototype, in order to reduce the height of the water-cracking zone (CTB), the softening of the roof rocks is carried out as a result of working out the first layer, and then, after the end of the displacements, the second layer, etc., is worked out until the layer is fully used. In the proposed method, the softening of the roof rocks is carried out ahead of the treatment face by creating crack defects by any of the known methods, for example, advanced torpedoing or the addition of expanding mixtures. As a result, it is possible to develop formations at full capacity without dividing them into separate layers, i.e., thin formations and medium formations.

From the above it follows that the feature under consideration (artificial decompression of the roof to achieve a specific goal in various ways

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by means of rock pressure control) is a new technological characteristic of action and gives a new positive effect, which consists in reducing losses in safety pillars under water bodies by reducing the height of the VEC and lowering costs in comparison with other methods of stockpiling.

The method is carried out as follows.

Within the boundaries of the safety pillar, that is, when the depth of the formation under the water body is less than the safe depth of its development under the specified object, which could cause a breakthrough of the water or an unacceptable increase in its inflow, they are pre-drilled from the preparatory workings in front of the treatment hole through certain lengths of long inclined wells into the rock mass of the roof, bottom faces which should not go beyond the zone of random collapse.

The latter is formed as follows.

As a result of the coal excavation, the displacement begins from the layers lying in the roof of the treatment mine. Having lost support, these layers begin to bend under the action of their own weight, then, having reached the limit of bearing capacity, they collapse, s. Following the first, a successive collapse of the overlying layers occurs until the next layer hangs or receives support on previously collapsed rocks. Starting from this layer in the rocks, the reservoir structure is preserved, and the area from the top of the formation to the mentioned layer is called the random collapse zone. Thus, in order to ensure a smoother course of the displacement process within the undermined rock mass, it is necessary at the very initial stage to reduce the degree of randomness of the collapse of the layers, having previously reduced their rigidity. According to research data, the height of the collapse zone reaches ten times the removable thickness of the formation.

Then, the drilled deviated wells are charged with explosives and exploded. To prevent the explosion of the immediate roof and the formation itself, a safety pack is left, the size of which from the experience of torpedoing is equal to three times the removed power of the formation. In the borehole, this value is determined by the lower end of the explosive charge. As a result of the explosion, an active fracture zone is created around the well, significantly reducing the stiffness of the layers. Next, a formation is worked out under a previously weakened caving zone. As a result, studies have shown that the degree of random collapse of the layers of this zone into the worked out space of the formation decreases, and accordingly, the process of displacement and deformation develops more smoothly.

no layers of the array located above

collapse zone. In this case, a zone of water-supply cracks propagates to a lower height, the development of which is associated with the degree of uneven subsidence, then

with deformations of the array, the smaller the deformation, the lower the height of the VEC. As a result of studies, it was found that the height of the VIZ above the worked out space of the reservoir, above which were previously

roof rocks are weakened, 40-50% less than the value that occurs without prior decompression. This makes it possible to carry out safe mining of the coal seam within the safety pillar under water

object with its depth below the last not less than 60% of the safe depth.

PRI me R. At one of the Intinsky mines

0 deposits at a depth of m below the river, the channel of which is oriented across the strike of the seam, lies a coal seam with a thickness of 5 m. The development of the formation is carried out by long columns along

5 stretch. The thickness of mudstones and siltstones in the suprahedral mass is 35% of the thickness of bedrocks. The river bed is hydraulically connected with pebble deposits, the soil of which is accepted.

0 lower boundary of the water body. Clay sediments under pebbles are absent (). According to clause 6. 2. The Protection Rules, this object belongs to the II group of water bodies. Safe Depth (Not) for this

The 5th layer is determined according to Table 6.2 of the mentioned Protection Rules, according to which at hr 0,, 5 m and the content in the thickness is 35%. mudstones and siltstones m. Since the actual depth of the bed

0 is less than safe (), then within the zone of the dangerous influence of the water body, a safety pillar is constructed, constructed along the lines drawn along the break angles from the maximum

5 river spill to the intersection with the reservoir. Formations with a thickness of 1.5 m are not developed with separation into layers, therefore, the method of mining pillars under water bodies in these conditions is not applicable. We carry out the development of reserves as a whole according to the proposed method. Preliminarily, from the preparatory workings in front of the mine face within the rear pillar by the method of advanced torpedo weakening, the roof rocks are weakened in the range from 3 to 10, i.e. from 4.5 m to 15.0 m with the thickness of the developed formation, 5 m. Then, under decompressed rocks mining coal from the pillar with lava. In this case, the PZT extends to a height equal to 0.5-0.6 of the PZV value, which is formed without the use of decompression. And this means that the safe development depth will be Nb.t: 0.6 Nb. that is, 80x0, m, which is less than the depth of the formation under the river (НСр. 65 m). Consequently, a complete extraction of coal from the pillar under the body of water is provided. The advantage of the proposed method compared to the prototype is to reduce the loss of minerals in the safety pillars, reducing the cost of preparatory work and ensuring the safety of work. These advantages are provided due to the fact that the rocks are softened previously from threaded workings in the range from three to ten times the removable thickness of the formation, counting from the roof of the latter.

The proposed method is intended to be used in reservoir deposits, especially in the main coal basins in the development of reservoirs under water bodies.

SUMMARY OF THE INVENTION A method for developing thin and medium thickness mineral strata from safety pillars under water bodies, including carrying out preparatory workings and excavating the formation with long columns along the strike within the safety pillar, characterized in that, in order to reduce mineral losses in safety pillars, reducing the cost of preparatory work and ensuring the safety of work, previously from the preparatory workings soften the rocks in pre elah from threefold to ten fold power of a removable reservoir, counting from the last roof.