RU2057251C1 - Method for open-cut mining steeply dipping ore bodies - Google Patents

Abstract

FIELD: mining. SUBSTANCE: gallery-by-gallery extraction of stripping rocks and minerals is performed. Method of previous kerf forming is used when achieving limit outline. Mining of ore located beyond quarry outline is carried out after defining size of unit structural blocks according presented dependence, determination of medium size of unit structural block along quarry height, and appropriate adhesion in mountain mass, and formation of working side in new bounds of the development. Formation of working side is performed by drilling vertical holes using main process equipment. EFFECT: mining ore body located below design bottom level of a quarry. 1 dwg

Description

 The invention relates to the mining industry and can be used in the development of deposits with steeply falling ore body in an open way when excavating marginal reserves under the bottom of the quarry and in its sides.

There is a method of mining steeply falling deposits in bursts, in which at each stage of the pit recess, its sides are carried apart, while the angles of their redemption at each subsequent stage are taken more gentle compared to the previous [1]
The disadvantage of this method is the increase in the marginal overburden coefficient from stage to stage and a decrease in quarry productivity during the beginning and completion of mining of each stage.

There is a known mining method, in which the stability analysis of boards composed of isotropic rocks is carried out immediately to the final pit depth according to scheme V of the VNIMI guidelines, when the side offset angle is determined by the plan of flat slopes, the same schemes are used to calculate the side offset angle of the hanging side of steeply falling deposits . With this method, the calculation of the bead angle is performed using the known values of the bulk density of the rocks, the angle of internal friction and adhesion in the massif. In turn, the adhesion in the massif is determined on the basis of data on the values of adhesion along cracks and in the sample, as well as the size and shape of elementary structural blocks and the depth of the quarry. The dimensions of the elementary structural blocks are taken on the basis of mass measurements of fracture parameters [2]
The disadvantage of this method is that even at the design stage, the calculations include the sizes of elementary structural blocks determined at the exploration stage, despite the fact that the size of blocks for most ore quarries increases with depth, therefore, the adhesion in the massif also increases. The underestimation of the increase in adhesion due to the change in the size of blocks when determining the angles of redemption of the sides of the quarry leads to an underestimation of the depth of the quarry or an increase in the volume of overburden in its contour.

 The invention solves the problem of deepening existing quarries with the aim of extracting all or part of the marginal reserves under the bottom of the quarry and in its sides by increasing the angle of redemption of the side from the side of the hanging pool.

This is achieved by the fact that in the method of open-cast mining of steeply falling ore bodies, including the horizontal excavation of overburden and minerals using drilling and blasting operations and the method of preliminary slot formation when setting the sides to the limiting position, ore mining is located beyond the open-cast mine contour under its bottom and in the sides on the last stage of refinement, is carried out by changing the angles of the redemption of the sides of the quarry, for which, in depth, they specify the size of the elementary structural blocks of the rock mass that composes the hanging b and to the end part of the pit, according to the formula:
l _n l _o [1 b exp (-cH _i )] (1) where l _{n is the} size of elementary structural blocks at the depth of the quarry H _i ;
b and c empirical coefficients determined experimentally, equal to 0.7-0.9 and 0.04-0.08, respectively;
l _{o the} size of the structural blocks at a depth exceeding the power of the discharge zone (N ≥ 500 m);
exp (cH _i ) e ^-cH i exponent;
e basis of the natural logarithm;
H _i considered quarry depth.

 Then determine the average (by the depth of the quarry) size of the elementary structural blocks and the corresponding adhesion in the array, after which the maximum depth of the quarry and the corresponding angle of the side repayment according to the stability factor are determined. After that, the quarry contour is adjusted in the recess zone, then a working board is formed in its new borders by drilling vertical wells with the main technological equipment and the quarry is being finalized.

 The drawing shows: steeply dipping reservoir; hanging and lying side of the reservoir; redemption angles of the hanging and lying sides of the reservoir; career depth.

 An increase in the repayment angle 1 from the side of the hanging side of the deposit compared to that adopted in project 2 is due to an increase in the size of elementary structural blocks. This pattern is typical for most ore deposits.

(2) где H90

ctg

(3)
γ, С_м и Φ соответственно объемный вес, сцепление и угол внутреннего трения породного массива.From the side of the hanging side of deposit 4, where there are no large weakening surfaces falling towards the recess, the stable slope height 3 for a given angle of its repayment 1 can be determined by the plan of flat slopes or calculated by the formula
H

(2) where is H90

ctg

(3)
γ, C _m and Φ, respectively, volumetric weight, adhesion and angle of internal friction of the rock mass.

λ C_к=

(4) где C' сцепление между поверхностями трещин (C' ≅ 0,05 МПа);
С_к сцепление породы в образце (для скальных пород обычно 10 ≅ С_к≅ 30 МПа);
а коэффициент;
l_ср. средний размер элементарных структурных блоков пород, слагающий законтурный массив;
λ

Прочность и размер блоков возрастает с глубиной отработки месторождения, причем интенсивность этого роста определяется, прежде всего, генетическим типом месторождения и пострудной тектонической историей развития района.The value of the angle of internal friction is determined by the results of laboratory tests with fairly high accuracy, the value of adhesion in the array is determined by the empirical formula:
C _m = C ′ +

λ C _k =

(4) where C 'is the adhesion between the surfaces of the cracks (C' ≅ 0.05 MPa);
C _{to the} cohesion of the rock in the sample (for rocks usually 10 10 C _to ≅ 30 MPa);
and coefficient;
l _cf. the average size of the elementary structural blocks of rocks composing the marginal massif;
λ

The strength and size of the blocks increases with the depth of development of the deposit, and the intensity of this growth is determined, first of all, by the genetic type of the deposit and the post-tectonic history of the development of the region.

 The size of the elementary structural block at any depth of field development is determined by the formula (1).

где l₁, l₂, l_n и H₁, H₂, H_n размеры блоков и соответствующие им глубины разработки.Simultaneously with the determination of adhesion values, the average value of the sizes of the blocks composing the board is determined by the formula:
l _cf. =

where l ₁ , l ₂ , l _n and H ₁ , H ₂ , H _n block sizes and the corresponding development depths.

 Given several values of the depths of the quarry and determining the average value of the block for each of them, the values of the adhesion of the array are found, then using a flat slope graph or formulas (1) and (2), a series of pairs is made up of the side height and its repayment angle sustainability factor.

 Based on these parameters, a graph is constructed of the margin of stability on the side of the recession of the sides for the hanging side of the deposit and the end sections of the quarry, after which the optimal option for the recess of the quarry is selected based on a comparison of the design and maximum (for the chosen version of the recess) side recession angles.

 Since the deepening of the quarry for the purpose of extracting the contour reserves begins at a time when most of the side has already been paid off, to ensure the extraction of the contour reserves, the side redemption angle is usually increased starting from the first outstanding horizon. In this case, to increase the angle of recession of the side, a special technology is used to form the side with the ebbs of the ledges by preliminary slitting. This provides the opportunity to increase the angle of inclination of the side.

PRI me R. For the conditions of the Central quarry of the Zhdanovskoye field, the following data were obtained in 1960 based on the study of fracturing in two exposed ledges by the VNIMI Institute: l _cf. 0.4 m; λ 0.025 for H 270 m, whence (at l 0.4 m const) for H 400 m and H 500 m there are λ values that are respectively equal (at a 7): 0.021 and 0.020. The angles of redemption of the sides according to the schedule of flat slopes at C _to 29 MPa; λ 30 ^about ; γ = 3.0 tf / m ³ and the above λ value for H 270, 400 and 500 m, respectively, is 66; 50 and 46 ^about .

The average block size with its corresponding depth is determined by the formula:
l _n 2.00 [1 0.90 exp (-0.048 H)] and, respectively, for a depth H 270, 400 and 500 m is equal to: 1.95, 1.98 and 2.00 m. For the same values of C _to and and, as in previous calculations, we find the λ values corresponding to the side height H equal to 270, 400 and 500 m: 0.028; 0.026 and 0.025.

Corresponding angles of redemption of the sides at N 270; 400 and 500 m will be equal: 70, 54, 50 ^о , i.e. in our case the total repayment corner bead can be increased to ^about 4, which allows to increase the depth of his career without separation of boards from 400 m to 462 m. It is also possible uglubki quarry to 577 m at maturity ^about 50 carbon.

Claims (1)

METHOD FOR OPEN DEVELOPMENT OF STEEL-FALLING ORE BODIES, including the horizontal excavation of overburden and minerals using drilling and blasting and the method of preliminary slit formation when setting the sides to the extreme position, characterized in that the ore mining located beyond the open pit in its open and below the bottom stage of refinement, removed by changing the boundaries of the quarry, which clarifies the change in the size of the elementary structural blocks of the rock mass, composing the hanging side and end parts STI career with formula depth
l _h = l _o [1 - b _{e x p} (- cH _i )],
where l _h is the size of the elementary structural blocks at the depth of the quarry H _i ;
b and c are empirical coefficients determined experimentally, 0.7 - 0.9 and 0.04 - 0.08, respectively;
l _o - the size of the structural blocks at a depth exceeding the power of the unloading zone (N> 500 m);
exp (-cH _i is the exponent;
H _i - the considered depth of the quarry,
Then, the average size of the elementary structural blocks and the cohesion in the array are determined by the average depth of the quarry and then the maximum depth of the quarry and the corresponding angle of the side redemption are determined by the stability factor, and the contour of the quarry is adjusted, then the working board is formed within the boundaries of the new contour by drilling vertical wells with basic technological equipment and modify the quarry.

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