RU2379622C1 - Method for shooting of ore from massif with flaky texture - Google Patents

Abstract

FIELD: blasting.

SUBSTANCE: invention is related to mining industry, namely to methods for shooting of ore from massif with flaky texture. Method includes drilling of parallel rows of vertical wells at the angle χ to line of internal bench edge, charging of wells with charges of explosive substance (ES), assembly of internal well and surface blasting nets and row short-delay blasting of ES charges with production of flat blast compression wave in each row. Angle χ is identified from the following ratio: χ = (-1)ⁿπ/2 + θ + (-1)ⁿ⁺¹γ-arcsin(ctgα·tgψ), where π is angle equal to 180°; n is index of cutting direction, nl in case direction of cutting goes from left to right when looking at internal edge of bench and n=0 in case direction of cutting goes from right to left at the same view; θ is angle between line of ore layers spreading and line of internal edge of bench; γ is angle between line of wells rows and line of crossing of impact compression wave front plane with horizontal plane; α is angle of ore layers falling; ψ is angle between plane of impact compression wave front plane and vertical line. It is possible to accept the value of angle among two values of angle χ, which correspond to various directions of cutting, when it is most close to 90°.

EFFECT: invention makes it possible to improve efficiency of softening of intergrain ore joints and technical and economical characteristics of the following ore processing.

2 cl, 10 ex, 1 dwg

Description

The invention relates to the mining industry, and in particular to methods of explosive breaking of ore from an array with a layered texture, and can be used, first of all, in the extraction of ferruginous quartzite by an open method.

A known method of explosive breaking of ore from an array with a layered texture, including drilling parallel rows of vertical wells, loading wells with explosive charges (explosives), installation of downhole and surface explosive networks and short-blown explosive charges [1].

The disadvantage of this method is that the softening of inter-grain bonds of the ore is carried out due to a very significant increase in the specific consumption of explosives. Moreover, the increase in the cost of drilling and blasting is not offset by an improvement in the performance of subsequent technological operations.

The closest technical solution to the claimed one is a method of explosive breaking of ore from an array with a layered texture, including drilling parallel rows of vertical wells at an angle χ to the line of the inner edge of the ledge, loading the wells with explosive charges (explosives), installing downhole and surface explosive networks and orderly short-blasting explosive charges with the formation in each row of a plane blast compression wave [2].

The disadvantage of the prototype is the low efficiency of softening of inter-grain bonds of ore, because the plane of the front of the blast wave of compression is oriented at an angle of 45 ° relative to the plane of the ore layers, at which maximum shear stresses occur in the plane of the layers. However, it is known that shear stresses are not the most effective in the destruction of rocks. Thus, the tensile strength of rocks during shear is significantly greater than the tensile strength of the same rocks. Therefore, this method does not significantly improve the technical and economic indicators of the subsequent redistribution of ore at the stages of its crushing, grinding and concentration.

The objective of the invention is to increase the technical and economic indicators of the subsequent redistribution of ore due to the effective softening of inter-grain bonds of ore masses with a layered texture during explosive breaking.

The technical result achieved in this case is to increase the efficiency of softening of intergranular ore bonds due to the development of tearing microcracks both in the controlled crushing zone and beyond, oriented along the ore layers and caused by tensile stresses acting normally to the planes of the layers.

The specified technical result is achieved by the fact that in the known method of explosive breaking of ore from an array with a layered texture, including the drilling of parallel rows of vertical wells at an angle χ to the line of the inner edge of the ledge, loading wells with explosive charges, installation of downhole and surface explosive networks and ordered short-blown explosive explosive charges with the formation in each row of a plane inclined explosive compression wave, the angle χ is determined from the relation

where π is an angle equal to 180 °;

n is the indicator of the direction of breaking, n = 1 when the direction of breaking is from left to right when looking at the inner edge of the ledge and n = 0 - when the direction of breaking is from right to left with the same form;

θ is the angle between the strike line of the ore layers and the line of the inner edge of the ledge;

γ is the angle between the line of the rows of wells and the line of intersection of the plane

front shock wave with horizontal plane;

α is the angle of incidence of the ore layers;

ψ is the angle between the plane of the front of the blast wave of compression and the vertical.

In addition, from the two values of the angle χ corresponding to different directions of breaking, take the value of this angle at which it is closer to 90 °.

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

In the prime cost of the concentrate, the destruction processes (crushing and grinding in mills) make up about 60% in the iron ore industry, including the grinding process - 50%. Therefore, the invention is aimed at improving the technical and economic indicators of the subsequent ore redistribution (crushing, grinding and beneficiation) due to the effective softening of intergranular bonds of ore masses with a layered texture during explosive breaking.

Studies conducted at the Moscow State University for the Humanities established the anisotropy of the microtexture of ferruginous quartzites. The sizes of ore grains (aggregates) along the lamination are in the range of 13-110, and perpendicular to the lamination - 9-80 microns. The isometric coefficient (the ratio of grain sizes in parallel and perpendicular to the layering) ranges from 1.0-3.3 with a confidence of 90%, and its average value is 1.54. This determines a large surface area of the grains and, accordingly, a large energy intensity of the destruction of intergranular bonds along the stratification as compared to those across it. Therefore, when blasting, it is necessary to ensure such stresses in the array that will lead to the predominant formation of detachment microcracks along the planes of the layers of ferruginous quartzites. The most effective in the destruction of rocks are tensile stresses, since the tensile strength is several times less than in shear, and on average an order of magnitude less than in compression. It is known that during the explosion of a cylindrical elongated charge in an elastic medium, the main ones are radial compressive and tensile polar stresses. Naturally, when the shock wave of compression is normal to the planes of the layers in the layered mass of microcracks of separation, due to tensile stresses, they will develop along the layers.

When detonating a series of borehole charges at a sufficient distance from the charge (outside the crushing zone), the resulting elastic wave propagating from the given series in the array can be considered, to a first approximation, as a plane compression wave without lateral constraint. If the plane of the front of such a wave is directed perpendicular to the planes of the layers of ferruginous quartzites, then the softening of the massif will occur mainly due to the development of separation microcracks oriented along the layers.

In addition, the accumulation of detachment microcracks in the massif contributes to the effective selective opening of ore grains, and this increases the yield of iron in the concentrate during the concentration of crushed ore. In this case, the softening of the array will take place outside the zone of controlled crushing, which leads to useful in this case, the dissipation of the energy of the explosion outside the zone and reduce seismic loads on the protected objects.

When drilling parallel rows of vertical wells at a specified angle χ to the line of the inner edge of the ledge, charging them with explosive charges

and orderly short-delayed blasting of charges, a guaranteed formation of a plane blast wave of compression in each row of charges is guaranteed, the front plane of which will be perpendicular to the planes of the layers of the ore mass, which leads to maximum softening of the mass.

Thus, in view of the foregoing, the totality of all the features set forth in an independent claim is indeed intended to achieve the indicated technical result and solve the problem of the invention.

The choice of two values of the angle χ corresponding to different directions of breaking, an angle closer to 90 °, as a rule, better satisfies the conditions for working out the ledge and conducting blasting operations.

The drawing shows a schematic representation of a ledge of an ore array with a layered texture with the location of the vertical borehole explosive charges during the blasting according to the present invention and the use of a detonating cord and reverse initiation.

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

On the surface of the ledge 1 of the ore massif with a layered texture, the line 2 of the strike of the ore layers and the angle of incidence 3 of these layers are determined by geological documentation. Then draw a line 4 of a series of vertical blast holes 5 at an angle χ to the line 6 of the inner edge of the ledge, determined by the ratio

where π is an angle equal to 180 °;

n is the indicator of the direction of blasting, n = 1 when the direction of blasting is from left to right when looking at the inner edge 6 of the ledge and n = 0 when the direction of blasting is from right to left with the same form;

θ is the angle between the line 2 of the strike of the ore layers and the line 6 of the inner edge of the ledge;

γ is the angle between the line 4 of the rows of wells and line 7 of the intersection of the plane 8 of the front of the shock wave of compression with the horizontal plane;

α is the angle of incidence of the ore layers;

ψ is the angle between plane 8 of the front of the blast wave of compression and the vertical.

After this, the marking of the wells 5 is carried out so that the lines 4 of their rows are parallel to each other. Then, wells are drilled, loaded with 9 explosive charges, followed by stemming (if necessary), and an orderly short-delayed explosion of explosive charges according to the diagonal initiation scheme.

In the form shown in the drawing, the explosive charges are detonated when the fighter 10 is placed, for example, at the level of the bottom of the ledge, and the downhole and surface explosive networks (not shown) are mounted from a detonating cord (L). When blasting around each borehole charge 9 of an explosive, a blast wave of compression forms with a front in the form of a truncated cone 11, the radii of the bases of which increase in time, and when connecting explosive charges in rows 4 with the help of a differential pressure, charges in a row are initiated sequentially with a deceleration of about 1 ms, determined the distance between the wells in the row and the detonation velocity of the explosive blast. Therefore, when blasting each row of explosive charges, two resulting fronts of the blast wave of compression are formed in the form of two inclined planes 8 (the drawing shows one plane and the second plane is symmetrical to the first relative to the vertical plane of the series of borehole charges). In this case, the plane 8 is located at an angle ψ to the vertical and at an angle γ to the line 4 of the rows of wells.

We introduce the right-handed system of Cartesian rectangular coordinates associated with the detonated block. We place the origin at an arbitrary point on the surface of the block and combine the XOY plane with this surface so that the OX axis is oriented parallel to the line 6 of the inner edge of the ledge. Then the direction of blasting from left to right (n = 1) will correspond to the positive direction of the x - χ _floor axis and from right to left (n = 0) - the negative direction of the X - χ axis _neg .

The angles ψ and χ are determined by the relations of elementary mathematics

where υ _control - the propagation velocity of the elastic wave in the array;

υ _BB - detonation velocity of the explosive well charge;

υ _LH - detonation velocity of explosive LH.

In formulas (2) and (3), the “-” sign (the angles ψ and γ are counted counterclockwise relative to the vertical plane of the rows of wells) corresponds to blasting in the positive direction (movement of plane 8 from left to right, n = 1), and the sign “+ »(The angles ψ and γ are counted clockwise relative to the vertical plane of the rows of wells) - blast in the negative direction (movement of plane 8 from right to left, n = 0).

In view of the above, for different directions of breaking, expression (1) will have the following form:

In this case, the angle β between the line 7 of the intersection of the plane 8 of the front of the compression wave with the step surface and the line 2 of the strike of the layers should be:

to break the ledge from left to right:

β _floor = θ-χ _floor + γ;

to break the ledge from right to left:

β _neg = θ-χ _neg + γ.

When the rows of wells are located at an angle χ to the edge line of the ledge, defined by relation (1), the planes 12 of the ore layers and plane 8 of the compression wave front are perpendicular and, accordingly, the maximum softening of the mass due to the development of tearing microcracks oriented along the ore layers and caused by tensile stresses, acting normally to the planes of 12 layers.

From the two values of the angle χ corresponding to different directions of breaking, take the value of this angle that most fully satisfies the conditions for working out a specific ledge and conducting blasting operations on it. Most preferred is the angle χ at which it is closer to 90 °.

Relation (1) is universal and valid for any conditions of short-blown blasting of ore masses with a layered texture, in which during the explosion of vertical borehole explosive charges of each parallel series of charges, the resulting plane front of a blast wave of compression is formed. In addition to the conditions presented in the drawing, this will take place, for example, with:

- blasting widely used in quarries using non-electric initiation systems such as PRIMADET, SINV and others for the installation of downhole blast networks and LH for a surface blast network. In this case, the initiation of explosive charges is carried out, as a rule, using the upper and lower fighters (intermediate detonators), whose non-electric detonators have different deceleration times. The time to slow down the detonator of the lower action is less than the time to slow down the detonator of the upper action, for example, 450 and 500 ms, respectively. This means that only a more profitable reverse initiation will take place, since the initiation of the upper action will not come from its non-electric detonator, but from the explosive charge (the time the detonation wave travels through the explosive charge from the lower action to the upper is more than an order of magnitude less than the time difference slowdowns of non-electric detonators of militants). That is, the diagram shown in the drawing is fully consistent with this version of the blasting;

- direct initiation of borehole explosive charges with the deployment of an action movie in the upper part of the charges. With this initiation, an explosive compression wave is formed around each charge with a front in the form of an inverse truncated cone, and the resulting flat front of the compression shock wave from the explosion of each row of charges will have an appropriate spatial arrangement;

- simultaneous initiation of borehole explosive charges within one row and their reverse or direct initiation, which can be realized, for example, by using electronic initiation. In this case, the angle γ = 0 ° and the plane 8 of the resulting front of the blast wave of compression will be parallel to the line of the rows of wells;

- multipoint simultaneous initiation of a borehole explosive charge over the entire height of its column and the simultaneous initiation of charges within one row or the initiation of these charges with a millisecond deceleration. In this case, a vertical plane 8 is formed of the resulting front of the blast wave of compression (angle ψ = 0 °), which is parallel to the line of the rows of wells (simultaneous initiation of charges of the series, angle γ = 0 °) or is located at an angle to this line (initiation of charges in a row with a millisecond about 1 ms deceleration, angle γ ≠ 0 °).

Method implementation examples

For conditions career Stoilensky angle of incidence α of layers varies from 60 ° to 120 °, the velocity ν and ν _{Ex BB} explosive propagation of the elastic wave in the array (glandular quartzite with the hardness of the scale prof. M.M.Protodyakonova f = 17) and the knock The explosives in the well are respectively 4.9 km / s and 5 km / s (for aquatol T-20GM). The angle between the plane of the front of the blast wave of compression and the vertical with the reverse (lower) and direct (upper) initiation is (2)

When initiating simultaneously over the entire height of the explosive charge column, the angle ψ = 0 °.

With the successive blasting of borehole charges in a row, they are connected only by a detonating cord (υ _ДШ = 6.5 km / s) without pyrotechnic moderators. Then, the correction for the angle γ of rotation of the plane of the front of the blast wave of compression around the vertical axis relative to the line of a number of wells (the angle between the line of the rows of wells and the line of intersection of the plane of the front of the blast wave of compression and the horizontal plane) is determined by the expression (3)

The angles ψ and γ are taken constant. The calculation of the angle χ of the orientation of the rows of wells relative to the inner edge of the ledge will be performed for different values of the angles θ and α. In this case, we will carry out the calculations according to the above formulas (4) and (5) for two cases of blasting direction: from left to right (in the positive direction of the x-axis - χ _floor ) and from right to left (in the negative direction of the x-axis - χ _sp ) and choose from two angles χ one that is closer to 90 °:

However, this does not exclude the possibility of using the other found value of the angle χ if it will more closely correspond to the conditions for working out the ledge and conducting blasting operations.

The angle β between the line of intersection of the plane of the front of the compression wave with the surface of the ledge and the line of strike of the layers should be:

to work out the ledge from left to right:

β _floor = θ-χ _floor + γ;

to work out the ledge from right to left:

β _neg = -θ + χ _neg + γ

At an angle ψ = 0 °, the angle β must always be equal to 90 °.

Example 1

The line of strike of the layers of ferruginous quartzite relative to the positive direction of the edge line of the ledge is an angle θ = 60 °. The angle of incidence of the layers is α = 60 °.

In accordance with (4) and (5), we have the following results:

χ _floor = -15 °; χ _neg = 67 °

From this it can be seen that the direction of breaking should be taken from right to left, positioning the rows of wells at an angle χ _sp - 67 ° relative to the inner edge of the ledge.

At an angle ψ = 0 ° we have:

χ _floor = 19 °; χ _neg = 101 °

In this case, the blasting is carried out from right to left, and the rows of wells are located at an angle χ _sp = 101 °: The angle β _{sp is} really equal to 90 °:

β _neg = -θ + χ _neg + γ = -60 ° + 101 ° + 49 ° = 90 °

Example 2

We take the angle θ equal to 90 °, and the angle α of incidence of the layers, as in example 1, -60 °.

Then:

χ _floor = 15 °; χ _sp = 97 °.

Here, the development of the ledge should be carried out from right to left with the arrangement of rows of wells at an angle χ _otr = 97 °.

At ψ = 0 ° we find

χ _floor = 49 °; χ _neg = 131 °

In this case, blasting can be carried out both from left to right, and from right to left. Really:

β _floor = θ-χ _floor + γ = 90 ° -49 ° + 49 ° = 90 °,

β _neg = -θ + χ _neg + γ = -90 ° + 131 ° + 49 ° = 90 °

Example 3

The angle of incidence α of the layers is also equal to 60 °, and the line of their strike makes an angle θ = 120 ° with the edge line of the ledge.

Wherein

χ _floor = 45 °; χ _neg = 127 °

The rows of wells are positioned at an angle χ _otr = 127 ° to the edge line of the ledge, and the development of the ledge is from right to left.

For ψ = 0 ° we have

χ _floor = 79 °; χ _neg = 161 °

Blasting should be carried out from left to right, and the rows of wells should be placed at an angle χ _floor = 79 °, that is, perpendicular to the line of strike of the layers:

β _floor = θ-χ _floor + γ = 120 ° -79 ° + 49 ° = 90 °

Example 4

As in examples 1-3, the angle of incidence α of the layers is 60 °, but the line of their strike makes an angle θ = 150 ° with the edge line of the ledge. Then

χ _floor = 75 °; χ _neg = 157 °

In this example, closer to 90 ° is the angle χ _floor = 75 °. Therefore, in this case, breaking is carried out from left to right. At ψ = 0 ° we get

χ _floor = 109 °; χ _sp = 191 °.

Blasting should be carried out from left to right, and the rows of wells should be placed at an angle χ _floor = 109 °.

Verification:

β _floor = θ-χ _floor + γ = 150 ° -109 ° + 49 ° = 90 °

Now we consider examples in which the angle of incidence α of the layers changes, and the angle θ remains constant and equal to θ = 60 °.

Example 5

Let α = 70 ° and θ = 60 °

Then we have

χ _floor = -2 °; χ _neg = 80 °

We carry out the blasting from right to left at an angle χ _otr = 80 °.

At ψ = 0 ° we find:

χ _floor = 19 °; χ _neg = 101 °

We carry out the blasting from right to left. We place the rows of wells at an angle χ _otr = 101 °. Check perpendicularity:

β _neg = -θ + χ _neg + γ = -60 ° + 101 ° + 49 ° = 90 °.

Example 6

Given α = 9 ° and α = 6 °.

We find:

χ _floor = 19 °; χ _neg = 101 °

Blasting is carried out from right to left, and the rows of wells are located at an angle χ _otr = 101 °.

In this example, the layers of ferruginous quartzites are arranged vertically (α = 90 °), therefore, regardless of the angle ψ of the deviation of the plane of the front of the compression wave from the vertical, the line of intersection of this plane with the surface of the step should be perpendicular to the line of strike of the layers. This is evident from the fact that for γ = 49 ° and χ _sp = 101 °

β _neg = -θ + χ _neg + γ = -60 ° + 101 ° + 49 ° = 90 °

Example 7

We take α = 110 °, and θ = 60 °.

Then

χ _floor = 40 °; χ _neg = 122 °

Blasting is carried out from right to left at χ _sp = 122 °.

When ψ = 0 ° we have:

χ _floor = 19 °; χ _neg = 101 °

We carry out the blasting from right to left. We place the rows of wells at an angle χ _otr = 101 °. Check perpendicularity:

β _neg = -θ + χ _neg + γ = -60 ° + 101 ° + 49 ° = 90 °

Example 8

Given α = 120 °, and the angle θ is also equal to 60 °.

We have

χ _floor = 53 °; χ _neg = 135 °

In this case, blasting is carried out from left to right with an angle χ equal to 53 °.

At ψ = 0 ° we get:

χ _floor = 19 °; χ _neg = 101 °

We carry out the blasting from right to left. The rows of wells are placed at an angle

χ _sp = 101 °. Verification:

β _neg = -θ + χ _neg + γ = -60 ° + 101 ° + 49 ° = 90 °

Thus, for ψ = 0 and constant angles θ = 60 ° and γ = 49 °, the angle χ does not depend on the angle α and, as shown in Examples 1 and 5, is 8, 19, and 101 °. This is due to the fact that for any α the product ctgα · tgψ is equal to zero.

This confirms the correctness of the universal formula (1) and the specific (for different n) formulas (4) and (5).

Now consider examples in which there is a simultaneous explosion of wells in a row. In this case, γ = 0.

Example 9

Angle θ = 45 °. The angle of incidence α of the layers is 60 °.

The orientation of the rows of wells is determined by the angles:

χ _floor = -79 °; χ _neg = 101 °

We accept χ _sp = 101 ° and the direction of breaking from right to left.

For ψ = 0 ° we get:

χ _floor = -45 °; χ _neg = 135 °

We carry out the blasting from right to left. We place the rows of wells at an angle χ _otr = 135 °. Check perpendicularity:

β _neg = -θ + χ _neg + γ = -45 ° + 135 ° + 0 ° = 90 °

Example 10

Angle θ = 60 °. The angle of incidence α of the layers is 60 °.

Here we have

χ _floor = -64 °; χ _neg = 116 °

We carry out the blasting from right to left, and we place the rows of wells at an angle χ _otr = 116 °.

For ψ = 0 ° we find:

χ _floor = -30 °; χ _sp = 150 °.

Blast the block from right to left. We place the rows of wells at an angle χ _otr = 150 °. Check perpendicularity:

β _neg = -θ + χ _neg + γ = -60 ° + 150 ° + 0 ° = 90 °.

Information sources

1. Kutuzov B.N. Rock Destruction by Explosion: A Textbook for High Schools. - 3rd ed., Revised. and add. - M.: Publishing House of the Moscow State Institute, 1992, p.439.

2. RF patent No. 2263278 according to class. F42D 3/04, 2004 (prototype).

Claims (2)

1. A method of explosive blasting of ore from an array with a layered texture, including drilling parallel rows of vertical wells at an angle χ to the line of the inner edge of the ledge, loading wells with explosive charges, installing downhole and surface explosive networks, and orderly short-blown explosive charges with the formation of in each row of a plane compression blast wave, characterized in that the angle χ is determined from the relation
χ = (- 1) ⁿ π / 2 + θ + (- 1) ^{n + 1} γ-arcsin (ctgα · tgψ),
where π is an angle equal to 180 °;
n is an indicator of the direction of blasting, n = 1 when the direction of blasting is from left to right when looking at the inner edge of the ledge and n = 0 when the direction of blasting is from right to left with the same form;
θ is the angle between the strike line of the ore layers and the line of the inner edge of the ledge;
γ is the angle between the line of the rows of wells and the line of intersection of the plane of the front of the blast wave of compression with the horizontal plane;
α is the angle of incidence of the ore layers;
ψ is the angle between the plane of the front of the blast wave of compression and the vertical. 2. The method according to claim 1, characterized in that of the two values of the angle χ corresponding to different directions of breaking, take the value of the angle at which it is closer to 90 °.

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