RU2563893C1 - Method of detonation in open-cast minings of rock masses with different strength values - Google Patents

Abstract

FIELD: mining.

SUBSTANCE: invention relates to mining industry and construction, namely to methods of detonation on open-pit minings of layered massifs of rocks with the lower less strong layer of rock and the upper stronger layer. The method includes drilling of down wells, their loading by combined borehole explosive charges with placement in the lower part of wells of less heavy explosive. The lower and upper parts of charges are dispersed by a rock inert interval. In the upper part of wells heavier explosive is placed. Then stemming of wells is performed and charges are initiated. During charging the lighter explosive in the lower part of wells is placed to the soil level of stronger layer of rock. The inert interval is made with the height from 1.75 to 2.5 of the well diameter d_well. Charges are initiated with the delay-action blasting of the upper part of charges with reference to their lower part.

EFFECT: increase of efficiency of explosion with decrease of output of boulder, average size of piece of blasted rock mass, specific consumption of explosive and scope of drilling operations.

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Description

The invention relates to the mining industry and construction, and in particular to methods of blasting in open-cast mining of layered rock masses with a lower, less durable rock layer and an upper, more durable layer.

A known method of blasting in open-cast mining layered rock masses with upper and lower stronger layers of rocks and a middle less durable layer, including drilling downhole wells, loading them with explosive charges with the dispersion of the parts of the charges with a rocky inert gap, the height of which is more than the height less solid rock layer, well plugging and initiation of charges [1].

However, this method cannot be used when blasting arrays consisting of only two layers of rock (the lower, less strong and the upper, more durable layer), both of which require explosive loosening.

The closest technical solution to the claimed one is a method of blasting open cast mines of different strength layered rock masses with a lower, less durable layer and an upper, more durable layer, including drilling downhole wells, loading them with combined borehole explosive charges (BB) with a charge less than powerful explosives, by dispersing the lower and upper parts of the charges with a rocky inert gap and placing a more powerful explosive in the upper part of the well, blocking wells and initiating charges vanie [2].

The specified method is intended specifically for blasting arrays consisting of a lower, less durable layer of rocks and an upper, more durable layer, requiring explosive cultivation. However, due to the location of the strong layer in the upper part of the ledge, the placement of a more powerful explosive in it and the approach of the upper part of the charge from this explosive to the surface of the ledge, an increase in the energy consumption of the explosion on useless forms of mechanical work (spread of pieces of rock and amplification of the shock air wave) and energy losses during the detonation of explosives and the release of gaseous detonation products into the atmosphere.

This reduces the efficiency of the use of explosion energy for loosening the rock mass and the efficiency (efficiency) of the explosion. Therefore, there is an increased yield of oversize, the average size of a piece of blasted rock mass, the specific consumption of explosives and the volume of drilling operations, which reduces the technical and economic indicators of blasting.

The objective of the invention is to increase the technical and economic indicators of blasting in open-cast mining of layered rock masses with a lower, less strong layer of rock and an upper, more durable layer.

The technical result achieved in this case is to increase the efficiency of the explosion while reducing the oversize yield, the average size of a piece of blasted rock mass, the specific consumption of explosives and the volume of drilling operations.

The specified technical result is achieved by the fact that in the known method of blasting in open pit mines, multilayered layered rock masses with a lower, less strong layer and an upper, more durable layer, including drilling downhole wells, loading them with combined borehole explosive charges (explosives) with placement in the lower part wells of a charge of a less powerful explosive, with dispersal of the lower and upper parts of the charges by a rocky inert gap and placement of a more powerful explosive in the upper part of the wells, jamming and the initiation of charges, according to the invention, in the process of loading a less powerful explosive in the lower part of the wells is placed to the soil level of a more solid rock layer, the inert gap is performed with a height of 1.75 to 2.5 well diameters, and the initiation of charges is carried out with an advanced short-delayed blasting of the upper part of the charges relative to their lower part.

The set of features indicated in the claims includes all the features, each of which is necessary, and all together are sufficient to obtain a technical result.

It is known that when blasting rock masses of different strengths, the use of combined explosive charges, i.e. consisting of explosives of different capacities with the placement of blast holes deep in stronger rocks of a more powerful explosive having a higher detonation velocity than in less strong rocks, it allows to increase the efficiency of explosive loosening and to increase the radius of the controlled crushing zone of stronger layers of the massif. It is also known that the use of dispersed charges increases the duration of the explosion on the destructible mass and the effectiveness of its loosening. Therefore, the use of these factors is the most rational for blasting in open-cast mines of diverse stratified massifs of rocks with a lower, less strong and an upper, more durable layer.

The placement of a less powerful explosive in the lower part of the wells to the soil level of the more durable layer during the loading of the wells allows the rock inert gap to be located completely in the stronger layer and to exclude the transfer of the explosion energy of the upper part of the charge to the lower less strong layer with the formation of a camouflage cavity in weak rock.

Performing an inert gap between rocks with a height of 1.75 to 2.5 borehole diameters is sufficient to prevent the transmission of detonation from the explosion of the upper part of the explosive charge to its lower part. Such a shortened length of the inert gap allows the initiation of charges with a faster, slower blasting of the upper part of the charges relative to their lower part with a simultaneous increase in the stemming length (removal of the upper part of the charge from the surface of the ledge).

With this implementation of the method, the mechanism of transferring the energy of the explosion to the array changes. Advance blasting of the upper, more durable layer with a simultaneous increase in the stemming length of the upper part of the charge provides the maximum destruction zone of the surface part of the ledge and improving the quality of the stemming during explosions of the lower part of the charge. In this case, the gaseous detonation products of the lower part of the charge open the initial cracks formed in the upper more durable layer from the explosion of the upper part of the charge. All this reduces the energy consumption for useless forms of mechanical work during the detonation of explosives and the release of gaseous detonation products into the atmosphere, increases the efficiency of the use of explosion energy for loosening the rock mass and the efficiency of the explosion while reducing the oversized yield, the average size of a piece of blasted rock mass, and the specific consumption of explosives and the amount of drilling work.

Thus, the combination of all the features of the claims really ensures the achievement of the specified technical result and solves the problem of the invention.

The drawing schematically shows the design of the borehole charge for implementing the proposed method.

Charges are placed in descending, usually vertical wells 1 and perform combined and dispersed. Each charge consists of the lower 2 part located in the lower 3 less solid rock layer of the blasting mass to the soil level 4 of the upper 5 more solid layer of the massif (roof layer 3), and the upper 6 part in layer 5. The lower 2 and upper 6 parts of the charge are dispersed shortened inert breed gap 7, the height l _ave is measured from 1.75 to 2.5 hole diameters of d _BH. To load the lower 2 part of the charge, a less powerful explosive is used, and the upper 6 part uses a more powerful explosive. The upper explosive-free part of the borehole is filled with stemming 8. Charges are initiated with short-delayed advance blasting of the upper 6 part of the charges relative to the lower 2 part using separate intermediate detonators 9 and 10 and one of the non-electric initiation systems (only shock wave tubes are shown in the drawing 11 and 12 of such a system).

The method is carried out by sequentially performing the following operations.

The blasting unit accepts the basic grid of wells, which is determined by known methods and results of blasting based on the data of the geological and surveying service of the enterprise from the condition of efficient crushing by the solid charge structure of the lower 3 less durable rock mass of the massif.

As a rule, vertical wells are drilled down the base grid 1, as a rule, and, according to the impact of the drilling tool on the face and visually the output of the fracture products during drilling (drill cuttings), the soil marks presented by the geological surveying service are 4 of the more durable upper layer of 5 rocks (lower roof 3 less durable layer).

Then, wells are loaded with combined dispersed explosive charges.

Initially, the wells are filled with a less powerful explosive, adopted at the enterprise for blasting similar less strong rocks. The lower 2 part of the charge is placed in the wells to the soil level 4 more durable upper 5 layer of rocks.

Thereafter, wells placed shortened inert breed gap 7 (debris during drilling waste enrichment breed or other inert material) at a height of from 1.75 to 2.5 hole diameters d _borehole, i.e. the gap 7 is completely located in a more durable layer and excludes the transfer of the explosion energy of the upper 6 part of the charge to the lower less strong layer with the formation of a camouflage cavity in a weak rock. The height l _{pr of the} gap should be minimally acceptable, but greater than the distance of detonation transmission from the explosion of one part of the charge to another and is determined by the type of explosive, the diameter of the charge and the properties of the blasted rocks and the material of the gap. Lower values correspond to smaller l _pr d _borehole diameter wells, and large - greater d _borehole. More accurate values of l _pr can be obtained by experimental explosions. At the same time, this increases the length l of the _bottomhole , improves its quality and allows for the simultaneous initiation of parts of the charge.

верхней части заряда.Next, the upper 8 part of the charge from a more powerful explosive is placed in the wells. This explosive is chosen in a known manner from the condition that the radii of the zones of controlled crushing are equal in the lower, less solid layer of rock and in the upper, more durable. The height is also determined in a known manner. $$l_{s\mathrm{but}R}^{\mathrm{at}}$$

top of the charge.

Clogging of the upper uncharged part of the wells is carried out with the same drilling material 8, which is used for the inert rock interval 7. The length l _zab 8 increases, which will increase the blasting efficiency, and will be equal to the height of the upper 5 more solid rock layer minus l _pr and l _zab .

To initiate charges using one of the non-electric initiation systems (NSI), such as "Exel" or "Primadet". To install the downhole blast network during the placement of the lower 2 part of the charge in the well, an intermediate detonator 10 of one or two explosive blocks with a short-delay detonator of the NSI and a shock wave tube 12 is lowered into the well with the exit to the ledge surface, and during placement in the upper 6 parts of the charge — an intermediate detonator 9, also with an NSI detonator and a shock wave tube 11. The surface explosive network is also mounted using shock wave tubes and special surface connecting tubes shackles NSI tagged with slow intervals. This allows the initiation of charges in any desired sequence with predetermined deceleration intervals both between explosions of the charges themselves and of individual parts of the charges.

After the installation of the surface explosive network is completed, charges are initiated according to the blasting scheme adopted by the enterprise with the short-blown anticipatory blasting of the upper 6 part of the charges relative to their lower 2 part. The deceleration time Δt between explosions of the parts of the charges is defined as the difference in time t _{n of the} deceleration of initiation of the lower 2 part of the charge and the time t _in deceleration of initiation of the upper 6 part of the charge. Times t _n and t _in can be set either directly by the NSI detonators installed in the intermediate detonators, or using detonators in the surface connecting blocks. The deceleration time Δt must be sufficient so that a direct blast wave of compression stresses can pass through the crushing zone and a rarefaction-tension wave can return through the same zone, producing the main rock destruction near the free surface of the ledge. In addition, time for the development of cracks and the movement (separation) of the rock of a stronger layer should be taken into account.

Such an implementation of the method leads to a change in the mechanism of transfer of explosion energy to the array. Advance blasting of the upper, more durable layer of rocks and an increase in the length of the bottom hole of the charge ensures an increase in the fracture zone of the surface part of the ledge and an increase in the quality of the stem during explosion of the lower part of the charge. The gaseous detonation products of the lower part of the charge open the initial cracks formed in the upper more durable layer from the explosion of the upper part of the charge. This reduces the energy consumption for useless forms of mechanical work and the loss of explosion energy in the process of detonation of explosives and the release of gaseous detonation products into the atmosphere, increases the efficiency of the use of explosion energy for loosening rock mass and the efficiency of the explosion while reducing the oversized yield, the average size of a piece of blasted rock mass, the specific consumption of explosives and the volume of drilling operations due to the expansion of the grid of wells.

Examples of the method.

We produce experimental blasting for crushing overburden of the Dzheroi-Sardara deposit at the Tashkur quarry of the Navoi Mining and Metallurgical Plant. Blasting blocks are represented by a multi-stratified layered rock mass with horizontal bedding of two layers sustained by thickness: a lower, less durable rock layer with a thickness of 5.5 m (dense calcareous clay, gypsum with a coefficient of f = 2 on the MM Protodyakonov scale, requiring explosive loosening) and the upper more durable layer with a thickness of 4.5 m (gravelites f = 5).

- 5,5 м, т.е. до уровня почвы верхнего более прочного слоя. Высоту l_пр породного промежутка из продуктов разрушения при бурении изменяли в зависимости от d_скв диаметра скважин. Верхнюю часть скважины заряжали Нобеланом 2080 - более мощным ВВ с существенно более высокой скоростью детонации и плотностью заряжания. Длину забойки принимали равной 0,2 l_скв или 2 м, что больше, чем при взрывании в соответствии с прототипом [2]. Инициирование зарядов осуществляли с использованием НСИ «Primadet». При этом осуществляли опережающее короткозамедленное взрывание зарядов верхней части относительно их нижней части. Время замедления Δt между инициированием частей зарядов составляло 17 мс.In all cases, vertical wells were drilled without a borehole with a depth of 1 _well - 10 m. The lower part of the wells was charged with Igdanite to a height $$l_{s\mathrm{but}R}^n$$

- 5.5 m, i.e. to the soil level of the upper, more durable layer. The height l _{pr of the} rock span from the fracture products during drilling was changed depending on d _{well borehole} diameter. The upper part of the well was charged with Nobelan 2080 - a more powerful explosive with a significantly higher detonation velocity and loading density. The stemming length was taken equal to 0.2 l _SLE or 2 m, which is more than when blasting in accordance with the prototype [2]. Initiation of charges was carried out using the Primadet NSI. In this case, an advanced short-delayed blasting of the charges of the upper part relative to their lower part was carried out. The deceleration time Δt between the initiation of the parts of the charges was 17 ms.

Example 1

части заряда - 2,06 м. Сетка скважин составляла 6,8×6,8 м (при использовании по прототипу 6×6 м).Taking into account the drilling, the diameter of the well was 220 mm. The height l _{pr of the} rock gap was 2 borehole diameters d _borehole or 0.44 m, and the length of the _stemming l _zab - 9.1 d _borehole , the length of the upper $$l_{s\mathrm{but}R}^{\mathrm{at}}$$

part of the charge - 2.06 m. The grid of wells was 6.8 × 6.8 m (when using the prototype 6 × 6 m).

Example 2

части заряда - 2,2 м. Сетка скважин составляла 5,9×5,9 м (при использовании по прототипу 5×5 м).Taking into account the drilling, the diameter of the wells was 170 mm. Height l _pr rock gap was 1.75 borehole diameter d _rms or 0.3 m, height tamping l _Zab - 11.8 d _wells, the upper length $$l_{s\mathrm{but}R}^{\mathrm{at}}$$

part of the charge - 2.2 m. The grid of wells was 5.9 × 5.9 m (when using the prototype 5 × 5 m).

Example 3

- 1,88 м. Сетка скважин составляла 8×8 м (при использовании по прототипу 7×7 м).Taking into account the drilling, the well diameter was 250 mm. The height of the rock inert gap was 2.5 borehole diameters d _boreholes or 0.62 m, the length of the _stump l _zab - 8 d _boreholes (2 m), the length of the charge $$l_{s\mathrm{but}R}^{\mathrm{at}}$$

- 1.88 m. The grid of wells was 8 × 8 m (when using the prototype 7 × 7 m).

During the tests, the oversize yield was reduced by 10-12%, the average piece size from 0.9 to 0.6 m, the specific explosive consumption by 20% and the volume of drilling work by 30% due to the specified expansion of the well network. This indicates a more complete use of the energy of the explosion, reducing losses on useless forms of operation of the explosion and increasing the efficiency of the explosion.

Information sources

1. Kutuzov B.N. Blasting techniques. Part 1. Destruction of rocks by explosion: Textbook for universities. - M.: Publishing House "Mountain Book", 2007. S. 419-420, Fig. 9.10, b).

2. Bibik I.P., Rakhmanov R.A., Ivanovsky D.S. Improving the efficiency of explosive loosening of multi-strength arrays during the development of the Jeroy-Sardara deposit of phosphorites // Mountain Journal. Special issue. Non-ferrous metals. - 2008. - No. 8. - S. 48-52, Fig. 4, III, c (prototype).

Claims (1)

The method of blasting in open-cast mining of multilayer stratified rock massifs with a lower, less durable rock layer and an upper, more durable layer, including drilling downhole wells, loading them with combined bore charges of explosives, with placement of a less powerful explosive in the lower part of the wells, and dispersing the lower and the upper parts of the charges with a rocky inert gap and the placement of a more powerful explosive in the upper part of the wells, blocking of the wells and initiation of charges, characterized in that during charging less powerful explosives in the bottom of wells arranged to soil level more durable breed layer inert interval operate with a height of 1.75 to 2.5 diameters of the wells, and the charge initiation is carried out with leading short-delay firing charges relative to the upper part of the lower part.

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