RU2178079C1 - Method of sloping high benches on opencast limiting contour - Google Patents

Abstract

FIELD: mining industry; applicable in sloping of high benches in opencast mining of kimberlite deposits. SUBSTANCE: method includes drilling of holes of contourside row to height of at least one working subbench at a distance of at least 14 hole diameters from design contour, then drilling of contour row holes in plane of formed high bench through its entire height, and the second row holes in each working subbench. Holes are charged with explosives and blasted, and broken rocks are withdrawn. First, loaded with charges and blasted are holes of contourside row, then the second row holes of upper working subbench, contour holes and the second row holes in each underlying working subbench. In this case, contour row holes are charged in lower part for height of underlying working subbench with charge density of 1-2 kg per meter run, and in upper part, they are charged with circular gap between charges and charge density of 4-8 kg per meter run. Broken rocks are withdrawn, first, from upper working subbench, then from contour zone and, at last from each underlying working subbench. EFFECT: increased stability of high benches due to reduced formation of fractures in rock mass behind contour and formation relatively smooth surface of bench slope. 3 dwg

Description

 The invention relates to the mining industry and can be used in open pit mining with ejection of high ledges on the limiting contour of the quarry.

 There is a method of mining the contour zone of the quarry, including the simultaneous development of the contour strip with blasting wells of the contour series (a. From. USSR 1025886 E 21 C 41/00). This order of work leads to an undoubted violation of the contour array, especially in its upper part. It is known that in the direction perpendicular to the axis of the charge, the zone of violation of the array extends along the surface of the ledge to a distance of 100-140 diameters of the charge, and in the depth of the array (lower part of the well) to a distance equal to 10-20 diameters of the charge. Therefore, the left marginal tape with a thickness of 6-7 m does not fully ensure the safety of the marginal massif over its entire height. A particularly dangerous security situation is created by violations of the marginal massif in the upper part of the ledge, since in the future, during a long period of operation, this section of the massif will be intensively destroyed.

 In addition, to test the near-edge strip with a thickness of 6-7 m, even with a decrease in the load on one well by reducing the distance between the wells in the contour row to 3-3.5 m, it will be necessary to use sufficiently powerful charges in the contour wells. So, for working out and loosening an array with a line of least resistance 6-7 m in wells with a diameter of 214-269 mm, the explosive charge density (BB) should be in the range of 30-45 kg per linear meter of the well, even when the grid is thickened between the contour wells. To place the specified number of explosives in one linear meter of a contour well for industrial explosives, only a continuous charge structure can be applied, which provides for the placement of explosives over the entire cross section of the well. And at the indicated location in the explosive contour borehole when it is blown up, a significant part of the energy will be transferred to the massif and therefore destroy it.

 In addition, the proposed method for mining the contour zone of the quarry cannot be carried out when setting the high ledges to the extreme position by doubling or wounding the working steps.

 The closest to the proposed technical essence and the achieved result is a method of ejection of ledges, which includes the formation of a detachable gap within the design contour of the quarry, mining of the near-edge array to the plane of the detachable gap and subsequent ejection of the ledge by blasting charges in shortened wells (a.s. USSR 1670133 E 21 C 41/26). The specified order of work will lead to the fact that the built-up plane of the ledge will not correspond to the design parameters and a convex ledge profile will be obtained. In the middle part of the built-in ledge below the shortened wells there will remain an unbroken array of the buffer zone up to the design contour. Since this buffer array at the time of the explosion of loosening wells will be located behind the cutting slot, it will not work well and even in the future will not be able to figure it out with an excavator. Moreover, the considered part of the buffer array cannot be worked out with shocking explosions of charges in shortened wells. It is known that at the end of the charge the array is worked out to a depth of only 5-7 diameters of the charge. The rest of the buffer array will necessitate a corresponding increase in the width of the safety berm.

 In addition, the proposed method for ejecting the ledges cannot be carried out when setting the high ledges to the extreme position by doubling or wounding the working steps.

 The aim of the present invention is to increase the stability of high ledges by reducing the formation of cracks in the contour mass and the formation of a relatively flat surface of the plane of the built-up slope of the ledge.

 This goal is achieved by the fact that in the known method, the protrusion of the ledges, including the drilling of contour and boreholes, their loading and blasting, shipment of rocks, is drilled at the beginning of the side-row wells to a height of at least one working approach at a distance of 14 well diameters from the design contour, then the contour row wells are drilled in the plane of the built-up high ledge to its entire height and the boreholes in each working approach, charge and blast wells, and rock is shipped. Moreover, first the wells of the contour row are charged and blown up, then the boreholes of the upper working step, then the boreholes of the contour row and finally the boreholes in each underlying working step, while the contour row wells are charged in the upper part with charges with an annular gap and with a charge density of 4-8 kg / linear m, and in the lower part - to the height of the underlying working approach by charges with a charge density of 1-2 kg / pog. m, and produce shipment of rocks at the beginning of the upper working sub-approach, then the marginal zone and finally each underlying working sub-access.

 The created shielding gap in front of the limiting circuit, when blasting boreholes in safety pillars, significantly limits the spread of harmful deformations and provides partial protection of the array located behind the shielding gap. It is known that in the direction perpendicular to the axis of the charge, violations propagate along the surface of the step to a distance of 100-140 charge diameters, and in the depth of the array (lower part of the well) to a distance of up to 20 charge diameters. Therefore, the rocks located between the shielding gap and the limiting contour are slightly destroyed, however, this is not enough for their excavation and shipment by the excavator. In this case, the upper part of the marginal mass is violated to a greater extent relative to the lower. Partially broken ledge with a long period of standing under the influence of precipitation and weathering will quickly collapse, especially intensively in the upper part. Therefore, after breaking and harvesting the main part of the safety pillars of the upper and middle working steps in the plane of the high ledge to be rebuilt, a number of contour wells are drilled on the limiting contour of the quarry to the entire height of the built-in ledge with a depth of 45 m.

 The upper part of the contour wells, corresponding to the height of the upper and middle sub-steps, is charged with charges, which, in the event of an explosion, crush and collapse the remaining marginal part of the safety pillars. Given that the resistance line along the entire height of the wells for these blasting conditions is only 3.5 m, the magnitude of the charges in this case can be minimized. Therefore, breaking can be carried out by charges with an annular gap and with a charge density of 4-8 kg / pog. m. With this design of the charge, its density and the width of the striking layer, traces of wells in which the charges are placed will remain on the surface of the rebuilt ledge. The remaining traces of the wells on the slope plane indicate that the massif has not undergone destruction during the explosion of charges in the contour wells.

 The lower part of the contour wells, corresponding to the height of the lower access point, is charged with charges, which ensure the formation of a screening gap in the considered part. To form a screening gap, charges with an annular gap and a charge density of 1.2 kg / linear arc are used. m

Execution example
The method of ejecting high ledges on the limiting contour of the quarry is illustrated by the schemes shown in FIG. 1 - 3, and is carried out as follows. On the limiting contour of the quarry, it is necessary to rebuild a continuous ledge 1 with a height of 45 meters by setting up 15-meter working sub-steps 2, 3, 4. When approaching mining operations on the upper working sub-step 2 to the limiting contour of the quarry, a safety pillar 5 with a width of 25-30 m is left. the contour part of the rebuilt ledge 1 at a distance equal to 14 well diameters (with a well diameter of 0.25 m, this distance will be 3.5 m), a shielding shield is created parallel to the plane of the future ledge 1, parallel to the plane of the future ledge Only the height of two sub-steps 2 and 3 (upper and middle). To do this, the near-edge row of wells 6 is drilled and explodes with the following parameters: well diameter 250 mm; drilling depth 30 m; the distance between the wells in a row of 3.5 m; type of charge - with an annular gap; charge density 1.2 kg / m; charge weight 36 kg.

 After this, the upper and middle safety pillars 5 and 7 are sequentially worked out by drilling, loading and blasting the boreholes 8 within each working approach 2, 3, 4. Typical parameters of drilling and blasting operations are used to drill the safety pillars 5 and 7: well diameter 250 mm ; drilling depth 17.5 m; distance from the shielding gap 4 m; the distance between the wells in a row of 8 m; the distance between the rows of wells is 8 m; weight of explosive charge in the well 480 kg.

 The blown up rock of the upper and middle safety pillars 5 and 7 in sequence from each is shipped and transported.

 Subsequently, in the plane of the rebuilt high ledge 1, a number of contour wells 9 are drilled on the limiting contour of the quarry for the entire height of the ledge 1 with a depth of 45 m.

 The upper part of the contour wells 9, corresponding to the height of the upper and middle sub-steps 2 and 3 (equal to 30 m), is charged with charges with an annular gap and with a charge density of 4-8 kg / linear meter. m. The lower part of the contour wells 9, corresponding to the height of the lower working sub-step 4, is charged with charges with an annular gap and with a charge density of 1-2 kg / linear meter. m

Parameters of BVR for the contour series of wells 9:
- diameter of wells - 250 mm;
- drilling depth - 45 m;
- the distance between the wells in the row is 3.5 m;
a) the charge of the upper part of the well:
- stemming length - 3 m;
- charge length - 27 m (from the bottomhole to the lower access);
- type of charge - with an annular gap;
- charge density - 3.5 kg / m;
- charge weight - 94.5 kg;
b) the charge of the lower part of the well:
- charge length - 15 m (from the upper mark of the lower approach to the bottom of the well);
- type of charge - with an annular gap;
- charge density - 1.2 kg / m;
- charge weight - 18 kg.

 After the explosions of charges in the contour wells 9, the upper remaining part 10 of the safety pillars 5 and 7 of a width of 3.5 m will be brought down on the lower working step 4, and a screening gap 11 will form in the lower part of the contour wells 9.

To continue work on setting ledge 1 to the limit position, it will be necessary to remove the blasted and collapsed part of the rocks. Then, the safety pillar 12 of the lower working step 4 is worked out by drilling, loading and blasting drill holes 8. Typical drilling and blasting parameters are used to test the safety pillar 12:
- diameter of wells - 250 mm;
- drilling depth - 17.5 m;
- distance from the shielding gap - 4 m;
- the distance between the wells in a row is 8 m;
- the distance between the rows of wells is 8 m;
- weight of explosive charge in the well - 480 kg.

 The blown up rock of the lower safety pillar 12 is shipped and transported, and the detuning of the high ledge 1 is completed.

 The method of ejection of high ledges on the limiting contour of the quarry is similarly carried out when doubling working sub-steps. In this case, work is carried out on two sub-steps. However, the sequence of operations and the parameters of drilling and blasting operations remain unchanged. The upper part of the rebuilt ledge is finally formed during the explosion of charges in contour wells with a charge density of 4-8 kg / m. The design of the lower part of the rebuilt ledge is carried out under the protection of the screening gap formed by the explosion of charges also in the contour row wells.

 The application of the proposed sequence and parameters of the detuning of high ledges ensures the complete safety of the marginal massif, especially in its upper part. In this case, the plane of the built-up slope is relatively smooth, thereby increasing the stability of the built-up high ledge.

 Due to the increased stability of high ledges, it is possible to reduce the width of the safety berms and increase the general angle of the rebuilt quarry. This will significantly reduce the volume of overburden excavation in the quarry.

Claims (1)

 A method for ejection of high ledges on the limiting contour of a quarry, including drilling contour and breaker wells, loading and blasting, shipping rocks, characterized in that at first they drill the contour rows to a height of at least one working approach at a distance of 14 diameters of wells from the design contour , then the wells of the contour row in the plane of the built-up high ledge to its entire height and the boreholes in each working subsurface, and first the wells of the contour row are charged and blasted, p is well Liner upper working podustupa, then contour line and the well borehole finally each fender in the underlying operating podustupe, wherein the number of charge wells contour in the upper part of the charge with an annular gap and with a charge density of 4-8 kg / rm. m, and in the lower part to the height of the underlying working access area with charges with a charge density of 1-2 kg / pog. m, the rock is shipped first at the top of the working sub-approach, then at the marginal zone and finally at each underlying working sub-access.

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