Method for obtaining a preset crushing ratio of fissured mountain mass and the required coefficient of heading advance per round to shot holes length ratio

FIELD: mining

SUBSTANCE: method comprises shot hole or bore-hole drilling, loading them with explosive material so that the bottom part of the shot hole the explosive material density or energy concentration would exceed the one in the wellhead of the shot hole. The mass of explosive material charge in the bottom part of the shot hole is calculated mathematically, depending on the line of least resistance value, the diameter of explosive material charge, fissure parameters and physical and technical mountain mass parameters, the rock pressure and detonation velocity of the explosive material.

EFFECT: enhanced efficiency and safety of drilling and blasting operations alongside with ore beneficiation efficiency.

1 dwg, 1 dwg

 

The invention relates to the mining industry, in particular the layer system of mining with the use of drilling and blasting operations.

Known method for improving the quality of the crushing mountain massif of the explosion in open pits, according to which the wellhead is BB with the lowest specific energy, and at the bottom of the wells CENTURIES with high specific energy, or by drilling at the bottom of the borehole boiler extensions [1].

However, the author is not listed, what is the diameter of the boiler in the area of the enlargement or what explosive weight (length of the explosive charge) with high energy, which you can choose depending on the physical and technical properties of rocks, detonation and geometrical parameters CENTURIES.

The closest technical solution is the method of loading holes with providing various concentrations of energy explosion in the bottom and core part of the bore-hole [2]. The length of the bottom of the bore-hole is 1/3 the depth of the hole, and the density of loading of 0.85 g/cm3for Ammonites, which creates a seal CENTURIES by zabojnik. The concentration of EXPLOSIVES in the core part is 0.5 kg/m, which is achieved by leaving an air gap and part of the bore-hole for tamping.

However, the bumper blast hole charges of EXPLOSIVES used in underground mining of ore, as a rule, charge 2/3 from glinister. That is half of the explosive charge will have a density of 0.85 g/cm3(high energy density), and the other half of 0.45-0.55 g/cm3(low energy density) due to the presence of the air gap.

In addition, when calculating the mass of the charge in the bottom part is not taken into account the line of least resistance (LNS), the diameter of the explosive charge fracturing parameters and physico-technical properties of the rock mass, detonation characteristics CENTURIES and size of rock pressure.

Method for obtaining a given degree of fragmentation of the fractured rock mass and the desired utilization of the bore-hole (KISH) explosion, including the drilling of boreholes or wells, loading EXPLOSIVES so that at the bottom of the hole density CENTURIES or concentration of energy were greater than in the mouth part of the bore-hole, characterized in that the mass of the charge sealed or vysokobarnogo CENTURIES at the bottom of the borehole is determined taking into account the magnitude LNS, charge diameter, fracturing parameters and physico-technical properties of rocks, the ground pressure, and velocity of detonation of EXPLOSIVES from the expression

where π=3,14,

W - the line of least resistance or the distance from the borehole to the electric circuit of the cavity, m;

dethe average size of the individual array, m;

F - measure of cracks is vitasti array;

d3- the diameter of the explosive charge, m;

µ - coefficient of friction between the separateness of the array;

P - value rock pressure between the air holes and Ironman cavity, PA;

D - speed detonation of EXPLOSIVES, m/s;

ν is the Poisson's ratio of rock.

The proposed method can provide high KISH due to seal CENTURIES and determine the mass of the bottom part of the explosive charge needed to overcome LNS. Also, do not seal CENTURIES in the mouth part can reduce the output of fines in the blasted rock mass, which increases the efficiency of enrichment, for example, uranium ores. The weight of CENTURIES with a high concentration of energy (due to the seal or the use of more powerful EXPLOSIVES) in the bottom part is determined taking into account the magnitude LNS, charge diameter, fracturing parameters and physico-technical properties of the rock mass, the ground pressure, and velocity of detonation of EXPLOSIVES. This allows you to increase security, efficiency blasting and ore.

The method consists in the following. Low mass of the explosive charge in the bottom part is not sufficient for blasting the rock mass from the array when the layer extraction of ores. Therefore, in the newly formed face appear "glasses", which reduces the efficiency of blasting. Inflated the weight of the explosive charge at the bottom leads to pieism is leczeniu ore and reduce the effectiveness of x-ray radiometric enrichment, for example, uranium ores.

The mass of the explosive charge in the bottom part, necessary for the conditions of the array with the maximum KISH, you can determine based on the first law Newton's stresses. The compressive stress occurring in the mountain at the moment of explosion of the explosive charge at a distance from a charge equal LNS should be equal to the sum of the frictional forces created by the rock pressure and lateral spreading of rock. Mathematical conclusion, see Appendix 1.

Output pereizluchennykh factions in the mouth part of the bore-hole with a size less than 40 mm (VMsignificantly depends on the density of loading (ρinand the velocity of detonation of EXPLOSIVES D. That is, VMdirectly proportional toand D2.

The increase in the density of loading CENTURIES from 600 to 850 kg/m3will lead to the increase of fines in 2 times in the mouth part of the bore-hole. Use instead of Ammonite EV with a value of D=4,2·103m/s, detonite with D=5,1·103m/s will lead to an increase in output of fines 1.47 times in the mouth part of the bore-hole. Mathematical conclusion VMgiven in Appendix 2.

The proposed method is as follows. The Poisson's ratio of rocks to determine the stage of exploration by known methods. The detonation speed D and the diameter of the explosive charge d3determine, using reference books. The value of the priori pressure in the area of the conducting layer Zachodni define or geophysical methods, or the well-known formula P=ρgH, where ρ is the bulk density of the rock mass, kg/m3., g - gravitational acceleration, m/s2N is the depth from the surface of the earth, m, the value For the concentration ratio of rock pressure in the area of the blow hole, usually it is equal To=2-3. Values f, µ determined from the deon the table

dem<0,050,05-0,150,15-0,400,40-1,0>1,0
F>1212-1010-88-6<6
µ<0,2of 0.2-0.30,3-0,450,45-0,6≥0,6

The value LNS W is determined by the passport drilling and blasting. For Ironman holes W is equal to the distance between them to the bumper - the minimum distance from the borehole to the surface of the electric cavity. For contouring - the minimum distance from the borehole to the exposed surface of the formed cavity.

The value of dedefine directly on the bottom output. Substituting

Islandia values of the parameters in formula (1), get the value of Q. Next, in the layer section of the Buryat electric, pneumatic and counting the holes. All boreholes charge. When using the same type BB ammo in the bottom part of the maximum compacted by power. The explosive cartridges in the mouth part is introduced into the holes without seals. When using different types of EXPLOSIVES in the bottom part of introducing more efficient CENTURIES (for example, demonic M, ammonal 200), priustevye less workable - Ammonite IV.

Next make installation network and explode in accordance with the passport drilling and blasting.

Example. Mine has a "Deep" JSC PIMCU in the array hard-shot grounds granites with the size of the separateness of 0.3-0.5 m produce ore extraction system tunneling layer extraction with hardening bookmark. Drilling the holes and blow by the conventional methods, charging boreholes Ammonite IV and podbrezova all the cartridges. Measurements of the results was performed by determining KISH (along the length of the "glasses") and the entry of small fractions (-40 mm) photopolarimetric method. The results after five cycles of explosives: KISH amounted to 0,7-0,85, output fraction - 40 mm was 37-45%.

Next it was decided to use the new method. The numerical values of the parameters in the formula (1): W=0.7 m; de=0.4 m; f=8 (see table); d3=0.04 m; the value of rock pressure at H=500 m, ρ=2,5·103kg/m3, g=9.8 m/s2, K=2 is equal to P=2,46·107PA; D=4,2·103m/s; ν=0,25. Substituting Chi is certain value in the formula (1), get Q=0,24 kg

Calculations by the formula (1) showed that the mass of the bottom sealing portion of the explosive charge must be equal to 0.24 kg is approximately one cartridge Ammonite IV. Subsequent experimental work in hard-shot grounds granites with a mass at the bottom of the charge, equal to 0.2-0.25 kg (1 cartridge), and the density of the loading mouth part of the charge (3-4 cartridge weight 0,6-1,0 kg, diameter 32 mm), is 0.64·103kg/m3revealed: KISH was 0.8-0.9, the output fraction - 40 mm 28-35%.

Thus, application of a new method allowed us to increase the KISH and reduce the yield of fines that helped improve the efficiency and safety of drilling and blasting operations, and the effectiveness of x-ray radiometric separation.

Sources of information

1. Efremov AM Preparation of rock quarries. - M.: Nedra. - 1980. - S (rice,m), s.

2. Technique and technology of blasting at mines // ABT. Heptaminol, Lowdose, WTO and others - M.: Nedra. - 1978. - S-187.

Appendix 1. Theoretical calculation of the mass of the explosive charge at the bottom of the borehole to increase the KISH

The greater utilization of the borehole when the descending layer excavation of ores improves the efficiency of mining operations and security level. To improve KISH recommended to condense CENTURIES at the bottom of the borehole or to use it more workable CENTURIES. However, you must determine the mass is In, sufficient for reliable blasting of the mountain massif in Ironman cavity. The underestimation of the mass of EXPLOSIVES will not receive the specified KISH, overstatement to pereseleniu ore, which has a negative effect on the enrichment, for example, uranium ores.

The mass of the explosive charge in the bottom part, sufficient for reliable blasting of the rock mass, can be calculated from the first law Newton's stresses. The compressive stress σin(r), resulting in a mountain range at a distance r (r=W, where W is LNS), must be equal to or exceed the sum of the frictional forces created by the rock pressure (σgand side thrust rocks (σbr) on the electric circuit cavity

According to [1] for spherical explosive charge

where ρinD, d3accordingly, the density of the explosive charge, the detonation speed CENTURIES, the diameter of the explosive charge; W - LNS; de, F -, respectively, the average size of the piece separately in a rock mass, a measure of the deformability of jointed rock mass, π=3,14.

According to [2]

where µ, ν, respectively, the coefficient of friction between the pieces of rock in shear, Poisson's ratio of rock, P - value rock pressure between the air holes and Ironman cavity.

Substituting (2) and (3) in (1), we obtain

Multiplying the left and right part of (4)get the formula to determine the mass of the explosive charge required for the release of the rock mass of Ironman cavity

The energy of a cylindrical explosive charge from the bottom part extends from spherical when considering processes at large distances (15-30 diameter of the explosive charge) [1]. In this case, l3=4d3[3]. Then (5) can be rewritten in

as

Annex 2. The output calculation pereizluchennykh fractions (-40 mm) when changing the detonation characteristics of CENTURIES.

Output pereizluchennykh fractions with size less than 40 mm can be determined from geometrical considerations by the formula

where

RMis the radius of the zone pereizluchennykh fractions near the explosive charge is defined in [2], m;

N is the number of holes in the bottom layer Zachodni;

S is a sectional area of the layer zagadki, m2;

ρinthe density of loading, kg/m3;

C is the speed of longitudinal waves in the rock specimen, m/s;

dM- the maximum size of a piece pereizmennoy rock mass, dM=0.04 m;

σp- the tensile strength of a rock specimen in gap, PA.

The analysis of the formula (7) after substitution in (8) shows that the output of small fractions of VMthe nternet is proportional to D 2and ρ2.

Bibliographic list

1. Tyupin NR. Geometrization of crushing zones of fractured array parallel to the axis of the explosive charge. // Izvestiya Vuzov. Mining magazine. - 1985, №1, - P.41-45.

2. Tyupin NR. Improving the efficiency of Geotechnology using explosive energy during the deformation of fractured strained rocks. // Thesis for the degree of doctor of technical Sciences - Moscow: VNIPI promtechnologii. - 2002. - Pp. 102, 104.

3. Pokrovsky GI Dependence of the form of range of the explosion on the shape and disposition of the charges. - In the book. Explosive business. - M.: Nedra. - 1964. No. 54/11. - S.

The method of obtaining a given degree of fragmentation of the fractured rock mass and the desired utilization of the bore-hole (KISH) explosion, including the drilling of boreholes or wells their loading EXPLOSIVES so that at the bottom of the hole density CENTURIES or concentration of energy was greater than in the mouth part of the bore-hole, characterized in that the mass of the charge sealed or vysokobarnogo CENTURIES at the bottom of the borehole is determined taking into account the magnitude LNS, charge diameter, fracturing parameters and physico-technical properties of rocks, the ground pressure, and velocity of detonation of EXPLOSIVES from the expression
,
where π=3,14;
W - the line of least resistance or the distance from the borehole to contact the RA Ironman cavity, m;
dethe average size of the individual array, m;
F is the indicator of fracturing;
d3- the diameter of the explosive charge, m;
µ - coefficient of friction between the separateness of the array;
P - value rock pressure between the air holes and Ironman cavity, PA;
D - speed detonation of EXPLOSIVES, m/s;
ν is the Poisson's ratio of rock.



 

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