RU2225509C1 - Method for explosive breaking in pit-faces of underground purifying enclosures - Google Patents

Abstract

FIELD: mining industry. SUBSTANCE: method includes crushing of rock by means of explosive charges with uniform placement of horizontal cables rows and of cables in rows. Crushing of inner pit-face section is performed by consecutive diagonal exploding of horizontal cables groups, placed in rows in staggered order symmetrically to pit-face center with forming of shelves and additional exposed surfaces. In the pit-face center trapezoid jads are formed by exploding horizontal cables in two adjacent rows with forming of exposed surfaces. Crushing of contour-adjacent pit-face areas is performed by means of cables explosions in series according to rows order. Between each couple of contour-adjacent area cables at least one non-charged cable may be placed. EFFECT: uniform granulometric composition of broken rock, increased effectiveness of explosive charges energy use. 2 cl, 2 dwg, 1 tbl

Description

The invention relates to the mining industry and can be used in underground mining of hard rock hard rock, in particular magnesite ores, drilling and blasting.

There is a method of layer-by-layer breaking, including crushing the rock mass by explosive charges with an orderly arrangement of holes (“Handbook of drilling and blasting operations” under the general editorship of MF Drukovanov, M., Nedra, 1976, p. 281, Fig. 111.37, a). When two rows of holes are blown up, three exposed planes are formed, but at the same time all the holes work only on one exposure plane along the line of least resistance. Hence the disadvantages of the traditional method of explosive blasting in the faces of underground treatment chambers - the incomplete use of the energy of explosive charges, the high consumption of explosive materials, and a large yield of fines.

As a prototype, a well-known method of blasting the middle part of the face was adopted (“Handbook of Drilling and Blasting Operations” under the general editorship of M.F. holes and wedge blasting. When blasting, three exposed planes are formed, but with this scheme only the first lower holes work on two exposed planes, while the rest explode in order on one side plane. The line of least resistance of the upper holes works only on one exposed plane, because the distance to the side surface is 2 times less than the distance between adjacent rows of holes in the direction of the side plane formed during the blasting. The blasting scheme, as described above, is also decent, only with a reduced line of least resistance, which leads to increased work of charges, and consequently, to overgrowing of ore. Hence the uneven particle size distribution, the incomplete use of the energy of explosive charges.

The objective of the invention is to ensure uniform particle size distribution of broken rock mass, a more complete use of the energy of explosive charges.

This is achieved by the fact that in the method of explosive blasting in the faces of underground treatment chambers, including crushing the array of explosive charges with a uniform arrangement of horizontal holes in rows and in rows, according to the invention, the crushing of the inner part of the face is carried out by sequential blasting diagonally of groups of horizontal holes displaced in rows staggered symmetrically to the center of the bottom of the chamber with the formation of horizontal ledges and the formation of additional exposed surfaces, while in the center the chambers of the battle are formed by trapezoidal cuts formed by blasting horizontal holes of two adjacent rows with the formation of exposed surfaces, and crushing of near-edge zones of the face is carried out by a regular blasting of holes equally spaced in them.

At least one non-rechargeable borehole is located between each pair of boreholes of the near-edge zones.

The displacement of the holes in the rows in a checkerboard pattern is symmetrical to the center of the face and the sequential blasting of them in groups along the diagonal ensures the formation of ledges and additional exposed surfaces for adjacent explosives (hereinafter BB). Charges work in four directions: along the lines of least resistance to a ledge and to a bare plane, which are almost equal, i.e. the work of an explosive charge increases by 3-4 times in comparison with the regular explosion of holes located in rows without bias, i.e. the coefficient of utilization of the energy of explosive charges increases 3-4 times.

The sequential diagonal blasting of holes from the center of the face to the near-edge zones creates a continuous change in the direction of blasting of charges and a complex configuration of the front of breaking rocks with the formation of additional open (exposed) surfaces using the effect of impact of the rock mass during the explosion between the surfaces of the formed horizontal ledges and exposed surfaces, which is positive affects the intensity of crushing of the rock mass. The output of substandard ore (fractions less than 90 mm) decreased from 30 to 2-4%.

Conducted patent research did not reveal similar technical solutions with such a combination of features that allows us to conclude about the novelty and inventive step, because this solution does not follow explicitly from the state of the art.

The domestic industry has all the means (materials, tools, equipment) necessary for implementing the method of breaking during the production of hard-to-explode rock.

Figure 1 presents a diagram of the staggered arrangement of holes and the sequential formation of ledges and free (exposed) surfaces, as well as the location of the holes of the near-edge zone; figure 2 - installation diagram of the blast network and the sequence of blasting holes.

Arabic numerals 1-47 represent the boreholes located in the inside of the chamber bottom in a staggered pattern symmetrically with an offset to its center, 48-68 - contouring edges of the sides and roofs equally spaced along the periphery, Roman numerals I-X - worked out spaces formed by diagonal blasting , XI-XII - zones of consecutive crushing by regular explosive blasting.

The proposed method of explosive blasting is used in underground operations at the Magnesitovaya mine of OJSC Magnesit Plant. The plant produces selective extraction of crude magnesite related to viscous and difficult to explode rocks with a strength factor of 10-11. The produced magnesite is intended for the production of refractory products. For the processing of premium magnesite, stringent requirements are imposed on its production, in particular for particle size distribution, and the linear dimensions of the piece should not be less than 90 mm.

The method of explosive blasting begins with marking holes in the height and width of the chamber in uniform rows with a pitch of 800 mm and a uniform arrangement in rows in increments of 970 mm with a staggered offset symmetrically to the center of the face. For the purpose of quick and accurate marking, simple design templates are used. The width of the chamber is 10 m, the layer height is 5 m, and the length can be 30 -70 m.

Drilling horizontal holes with No. 1-69 with a diameter of 40-43 mm to a depth of 2.7 m is carried out by means known in the art, for example, the Minimatic drilling rig, equipped with two hydraulic perforators.

The bore holes are charged with explosive charges, which are used as cartridges ammonium 6 LH, and in blast holes - charges 3 VVK.

The sequence of breaking the array in the underground chamber according to the proposed method is shown in figure 1. The breaking of the inside of the array begins with the formation of trapezoidal cuts I-II in the center of the bottom of the chamber, repeating every 2 rows by blowing 3 horizontal holes in odd rows and 2 holes respectively in even rows, i.e. diagonally to the center of the face (1-2-3, 4-5), with the formation of small horizontal ledges and inclined exposed surfaces. The central cuts along the axis in the vertical direction are repeated (cuts IV, V, VII). On the formed exposed surfaces 1-4, 3-5, explosive charges of neighboring holes work (6-7-8-9). As a result of breaking, the rock is crushed with the formation of horizontal ledges 7-4, 5-9 and the formation of exposed surfaces 6-7, 8-9 for explosive charges of adjacent holes. Further breaking of the mass by crushing is similar to the methods described above with successive blasting and the formation of new ledges and exposed surfaces. The worked out zones are shown by the numbers of the Roman alphabet. The blasting is carried out by low-energy waveguides SINV-Sh-5

The crushing of the near-edge zone (sides and roof) of the chamber is carried out by orderly blasting of the contour rows of holes 48-68 by means known in the art. Between each pair of rechargeable boreholes there is one non-rechargeable borehole. The sides and the roof are even, everywhere halves of the contour holes are traced (beating spaces - XI, XII).

The installation diagram of the electric blast network in FIG. 2 reflects the blasting sequence of the connected charged holes and identifies the formation order of the worked out zones in FIG. 1.

The sequence of explosions can be presented in the table:

Thus, the application of the proposed method of explosive blasting at the mine "Magnesite" allowed:

- more than 10 times to reduce the output of the fine fraction (less than 90 mm) with a more uniform particle size distribution;

- reduce the consumption of basic materials by 10-20% during blasting operations;

- reduce the time of drilling the faces of the chambers;

- reduce the time of charging holes by simplifying the installation of the blast network.

Claims (2)

1. The method of explosive blasting in the underground faces of the chambers, including crushing the array of explosive charges with a uniform arrangement of horizontal holes in rows and rows, characterized in that the crushing of the inner part of the face is carried out by sequential blasting diagonally of groups of horizontal holes, staggered in rows in a checkerboard pattern symmetrically to the center of the face with the formation of ledges and the formation of additional exposed surfaces, while trapezoidal cuts are formed in the center of the face, formed blasting horizontal drilling two adjacent rows to form the exposed surfaces, and crushing the marginal zones slaughter carried poryadnym blasting equally spaced drill holes in them. 2. The method of explosive blasting in the underground faces of the chambers according to claim 1, characterized in that at least one non-rechargeable borehole is placed between each pair of boreholes of the contour zones.

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