Method for realizing poor-rich separation of layered ore body of underground phosphorite mine through blasting

Abstract

The invention provides a method for separating poor and rich stratified ore bodies of an underground phosphorite mountain through blasting. And rich ores and lean ores are recovered in a manner of one-time drilling, multiple-time blasting and respective deslagging in layered mining. Links such as danger elimination, deslagging, charging, wiring and re-detonation are needed after each time of blasting, so that the operation cost is high and the production efficiency is low. The invention discloses a method for realizing poor-rich separation of stratified ore bodies of an underground mine through one-time blasting. The method comprises the following steps: determining ranges of rich ores in the middle and lean ores at the top and the bottom on a working surface; empty holes, slotting holes, auxiliary holes and peripheral holes are formed according to the designed differentiated hole net parameters, the charging structure and the detonating sequence; after blasting, the middle rich ore is thrown and blasted away from the working face to form a far muck pile, and the top and bottom lean ore is loosened and blasted to form an in-situ muck pile. According to the invention, rich ore and lean ore can be separated through one-time blasting, and recovery of rich ore and lean ore can be completed through classified shoveling. And compared with layered mining, operation links can be reduced, the operation cost is reduced, and the production efficiency is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of underground mining, and in particular relates to a method for separating rich and poor layered ore bodies in underground phosphate mines by blasting. Background Art

[0002] Ore grades are mainly classified according to the content of useful minerals in the ore, that is, the ore grade. For example, rich ore refers to ore containing a large amount of useful minerals, which can be directly used to produce industrial products after simple purification; lean ore refers to ore containing a small amount of useful minerals, which requires deep processing or special processes to be used. Therefore, downstream companies in the mining industry have a demand for both rich and lean ore. It is an important task for mining companies to improve the economic value of ore deposits by formulating reasonable mining plans to realize the separate mining of rich and lean ore.

[0003] The ore grade of each layer in the layered ore body usually needs to be determined through geological exploration, and some ore bodies can also be determined by the appearance characteristics of each layer. After determining the ore grade of each layer, the mining company will divide the layered ore body into rich ore area and poor ore area according to the grade requirements of rich ore and poor ore, and use the layered mining method to separate the rich ore and poor ore. Layered mining uses one drilling, multiple blasting and separate slag to recover rich ore and poor ore. After each blasting, it is necessary to clear the danger, slag, charge, connect the wire and re-detonate. Therefore, layered mining will increase the operation links, increase the operation cost and reduce the production efficiency. Therefore, the effective separation of rich ore and poor ore in one blasting of the layered ore body is one of the problems to be solved in mining operations. Summary of the invention

[0004] In order to solve the technical problem that rich ores and lean ores in layered ore bodies need to be mined in layers and blasted multiple times, the present invention proposes a method for separating rich and lean ore bodies in underground mines by one blast.

[0005] To achieve the above-mentioned purpose of the present invention, the present invention provides a method for separating the rich and poor layered ore bodies in underground mines by blasting. This is achieved through the following technical scheme: determine the grade distribution of the layered ore body on the drilling and blasting working surface, and divide the range of the middle rich ore and the top and bottom lean ore into the range of the middle rich ore and the top and bottom lean ore in combination with the ore grade classification. Arrange empty holes, slot holes, auxiliary holes and peripheral holes on the working surface. The slot holes and auxiliary holes constitute the throwing blasting holes, and the peripheral holes constitute the loosening blasting holes. Charge the slot holes, auxiliary holes and peripheral holes. Connect the slot holes, auxiliary holes and peripheral holes, and set the detonation point and detonation time. After detonation, the middle rich ore is thrown away from the working surface to form a distant blast pile, and the top and bottom lean ore is loosened to form an in-situ blast pile. The distant blast pile and the in-situ blast pile are classified and shoveled to achieve the separation of the rich and poor ore bodies.

[0006] The specific steps are as follows: (1) Determine the thickness and grade of each ore layer on the drilling and blasting working face. Use the weighted average method to determine the grade of the combined ore layer. The middle combined ore layer meets the grade requirements of rich ore, and the top and bottom combined ore layers meet the grade requirements of lean ore.

[0007] (2) Arrange empty holes, cut holes, auxiliary holes and perimeter holes on the working face. The empty holes, cut holes, auxiliary holes and the perimeter holes on both sides are located within the middle rich ore range, while the top and bottom perimeter holes are located within the top and bottom lean ore ranges. The empty holes and auxiliary holes are perpendicular to the working face, the cut holes are inclined towards the center line of the working face, and the perimeter holes are inclined away from the center line of the working face. (3) Use differential charging in the empty holes, cut holes, auxiliary holes and perimeter holes. Only the bottom of the empty hole is strengthened with charge, the charge density in the cut holes takes the normal value, the charge density in the auxiliary holes increases with the increase of hole depth, and the charge density in the perimeter holes takes a low value.

[0008] (4) Connect the empty holes, cut holes, auxiliary holes and perimeter holes and set the initiation sequence. Among them, the empty holes are initiated first, the cut holes are the first-stage blasting and the second-stage blasting, the auxiliary holes are the third-stage blasting, and the perimeter holes are the fourth-stage blasting.

[0009] (5) Initiate the blast. The middle rich ore is thrown and blasted away from the working face to form a distant muck pile, and the top and bottom lean ore is loosened and blasted to form an in-situ muck pile. The distant muck pile and the in-situ muck pile are classified and shoveled to achieve the separation of rich and lean ore bodies.

[0010] In the step (1) described above, the thickness and grade of each ore layer in the layered ore body are known. Use the weighted average method to determine the grade of the combined ore layer

[0011] The rich ore layer described above meets the grade ≥ 26.5%; the lean ore layer meets 24.5% > grade ≥ 18%. The grade of phosphate rock refers to the content of phosphorus pentoxide (P 2 O 5 ) in the phosphate rock. In the step (2) described above, empty holes are arranged in the middle of the ore body working face, at least two rows of cut holes are symmetrically arranged on both sides of the empty holes, auxiliary holes are arranged around the empty holes and the cut holes, and finally perimeter holes are arranged around the auxiliary holes; among the at least two rows of cut holes, the row closest to the empty hole is the first row of cut holes, and so on as the Nth row of cut holes.

[0012] At least two rows of cut holes can be understood as the row closest to the empty hole being the first row of cut holes, and a second row of cut holes is set after the first row of cut holes, and so on, multiple rows of cut holes can be set. In some embodiments, generally two rows of cut holes are set.

[0013] The empty holes, cut holes, and auxiliary holes are all located within the range of the middle rich ore; The perimeter holes are distributed in the top lean ore, bottom lean ore, and middle rich ore, and surround the auxiliary holes; the perimeter holes on both sides located in the middle rich ore area are the side perimeter holes, and the top and bottom perimeter holes are located in the top lean ore and bottom lean ore.

[0014] The angle at which the cut holes incline towards the center line of the working face is 5 - 10°, and the angle at which the perimeter holes incline away from the center line of the working face is 3 - 5°.

[0015] In some preferred cases, the angle at which the cut holes incline towards the center line of the working face is 10°, and the angle at which the perimeter holes incline away from the center line of the working face is 5°.

[0016] The depth of the empty holes is 2.3 - 2.8 meters (including the over - depth of 0.2 - 0.4 meters), the hole diameter is 100 - 110 millimeters, and the hole spacing is 0.6 - 1.0 meters; The depth of the cut holes is 2.0 - 2.5 meters, the hole diameter is 40 - 60 millimeters, and the hole spacing is 0.6 - 1.0 meters; The depth of the auxiliary holes is 2.0 - 2.5 meters, the hole diameter is 40 - 60 millimeters, and the hole spacing is 0.6 - 1.0 meters; The depth of the perimeter holes is 2.0 - 2.5 meters, the hole diameter is 40 - 60 millimeters, and the hole spacing is 0.6 - 1.0 meters.

[0017] In step (3) of the above, for the differential charging, only the bottom of the empty hole is strengthened with charge, the charge density in the cut holes takes the normal value, the charge density in the auxiliary holes increases with the increase of hole depth, and the charge density in the perimeter holes takes a low value, which means adjusting the charge density of the blast holes by controlling the charge length (i.e., the number of cartridges).

[0018] In the 0.2 - 0.4 - meter over - depth range at the bottom of the empty hole, a strengthened charge package (usually 3 - 5 cartridges) is loaded, and the middle section is not blocked.

[0019] The charge length of the cut holes is 1.5 - 1.8 meters, and the stemming length is 0.4 - 0.7 meters.

[0020] The charge length of the auxiliary holes is 1.8 - 2.1 meters, and the stemming length is 0.1 - 0.4 meters.

[0021] The charge length of the side perimeter holes on both sides is 1.2 - 1.5 meters, and the stemming length is 0.7 - 1.0 meters.

[0022] The charge length of the top and bottom perimeter holes is 1.2 - 1.5 meters, and the stemming length is 0.7 - 1.0 meters.

[0023] The explosive roll is rock emulsion explosive with a diameter of 32 mm, a length of 300 mm and a mass of 300 g. It adopts a digital electronic detonator and a special detonator for the digital electronic detonator as the detonation power source. The digital electronic detonator is installed at the bottom of the blast hole for reverse detonation.

[0024] In the step (4), the hollow holes are detonated first, the first row of slot holes are detonated as the first blast, the Nth row of slot holes are detonated as the second blast, the auxiliary holes are detonated as the third blast, and the peripheral holes are detonated as the fourth blast.

[0025] In the step (5), the delay between the empty hole and the first row of slotted holes is 30-50 milliseconds, the delay between the first row of slotted holes and the Nth row of slotted holes is 30-50 milliseconds, the delay between the Nth row of slotted holes and the auxiliary holes is 100-500 milliseconds, and the delay between the auxiliary holes and the peripheral holes is 100-500 milliseconds.

[0026] In summary, the outstanding advantage of the present invention is that it can separate the rich ore and the lean ore in one blast by dividing the range of the rich ore and the lean ore in advance, adopting differentiated hole arrangement and charge structure, and using micro-difference controlled blasting, thereby reducing the operation links, reducing the operation cost, and improving the production efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 :Division map of rich and poor ore ranges on the working face.

[0028] Figure 2 : Diagram of blasthole structure on the working face.

[0029] Figure 3 : Diagram of the detonation network on the working face.

[0030] Figure 4 : Distribution map of blast pile after blasting. DETAILED DESCRIPTION

[0031] To better describe the present invention, a method for separating rich and poor ore bodies in underground mine layered ore bodies by a single blast is further described in detail below in conjunction with the accompanying drawings.

[0032] (1) Based on Figure 1 , the thickness of each ore layer in the layered ore body and taste Known. The weighted average method is used to determine the grade of the combined ore layer The middle combined ore layer meets the grade requirements of rich ore, and the top and bottom combined ore layers meet the grade requirements of lean ore.

[0033] (2) Based on Figure 2, empty holes, cut holes, auxiliary holes, and perimeter holes are arranged on the working face. The empty holes, cut holes, auxiliary holes, and the perimeter holes on both sides are located within the range of the middle rich ore, while the perimeter holes at the top and bottom are located within the range of the poor ore at the top and bottom. The diameter of the blast holes, the hole spacing, the stemming length, and the overburden depth should be adjusted and determined according to the blasting test results. The empty holes and auxiliary holes are perpendicular to the working face, the cut holes are inclined towards the center line of the working face, and the perimeter holes are inclined away from the center line of the working face. The inclination angles of the cut holes and perimeter holes should be adjusted and determined according to the blasting test results.

[0034] (3) According to Figure 2 , charge the empty holes, cut holes, auxiliary holes, and perimeter holes. Continuous charging is used in each hole, and the stemming depth is adjusted and determined according to the blasting test results. Only the bottom of the empty hole is strengthened with charge, the charge density in the cut hole takes the normal value, the charge density in the auxiliary hole increases with the increase of the hole depth, and the charge density in the perimeter hole takes a low value. The specific charge density is adjusted and determined according to the blasting test results.

[0035] (4) According to Figure 3 , connect the empty holes, cut holes, auxiliary holes, and perimeter holes, and set the initiation sequence. Among them, the empty holes are initiated first, the cut holes are for the first and second stage blasting, the auxiliary holes are for the third stage blasting, and the perimeter holes are for the fourth stage blasting. The delay time for each stage is adjusted and determined according to the blasting test results.

[0036] After the empty holes and cut holes are blasted, a vertical wedge-shaped cut area is formed. After the auxiliary holes are blasted, a throwing area is formed. After the perimeter holes are blasted, a loosening area is formed.

[0037] (5) According to Figure 4 , after initiation, the middle rich ore is thrown and blasted away from the working face to form a distant muck pile, and the poor ore at the top and bottom is loosened and blasted to form an in-situ muck pile. There is a small amount of ore debris between the distant muck pile and the in-situ muck pile, which can be incorporated into the in-situ muck pile for treatment. The distant muck pile and the in-situ muck pile are classified and shoveled to achieve the separation of rich and poor ores in the ore body.

[0038] Example 1 (1) The thickness and grade of each ore layer in the stratified ore body are known. The weighted average method is used to determine the grade of the combined ore layer. The middle combined ore layer meets the grade requirements of rich ore, and the combined ore layers at the top and bottom meet the grade requirements of poor ore.

[0039] According to Figure 1, in the embodiment of the present application, the width of the mining face is 6 meters and the thickness is 4 meters. The ore body is divided into layers from top to bottom as dolomitic banded phosphorite, massive phosphorite, dolomitic striped phosphorite, massive phosphorite, argillaceous banded phosphorite, with thicknesses of 0.5 meters, 0.5 meters, 1.1 meters, 0.4 meters, and 1.5 meters respectively, and grades of 20%, 32%, 26%, 32%, and 22% respectively. The combined grade of the dolomitic banded phosphorite at the top and the argillaceous banded phosphorite at the bottom is 21.5%, which is lean ore (24.5% > grade ≥ 18%); the combined grade of the massive phosphorite, striped phosphorite, and massive phosphorite in the middle is 28.4%, which is rich ore (grade ≥ 26.5%).

[0040] The existing technology is to adopt the stratified mining method. In the first step, the middle rich ore is mined, and in the second step, the top and bottom lean ore is mined. It requires two blasts, and after each blast, operations such as danger removal, mucking, charging, connection, and re - initiation are needed. Therefore, stratified mining will increase the operation links, improve the operation cost, and reduce the production efficiency.

[0041] (2) Empty holes, cut holes, auxiliary holes, and perimeter holes are arranged in the working face. The empty holes, cut holes, auxiliary holes, and the perimeter holes on both sides are located within the middle rich ore area, while the top and bottom perimeter holes are located within the top and bottom lean ore areas.

[0042] According to Figure 2 , in the embodiment of the present application, empty holes are arranged in the upper - middle part of the rich ore area, arranged in a single row, with a quantity of 2, hole spacing of 0.8 meters, vertical holes, hole depth of 2.8 meters (including an over - depth of 0.3 meters), and hole diameter of 105 mm; The cut holes are arranged on the left and right sides of the empty holes, arranged in two rows, with a total quantity of 8, hole spacing of 0.8 meters, row spacing of 0.8 meters, inclined holes, angle of 10°, hole depth of 2.5 meters, and hole diameter of 45 mm; Auxiliary holes are evenly arranged between the cut holes and the upper and lower boundaries of the rich ore area, with a total quantity of 18, hole spacing of 0.8 meters, vertical holes, hole depth of 2.5 meters, and hole diameter of 45 mm; Perimeter holes are evenly arranged between the two sides of the auxiliary holes and the left and right boundaries of the rich ore area, and perimeter holes are arranged in the top and bottom lean ore areas so that the perimeter holes surround the auxiliary holes. The quantity is 26, hole spacing of 0.8 meters, inclined holes, angle of 5°, hole depth of 2.5 meters, and hole diameter of 45 mm.

[0043] After the empty holes and the cut holes are detonated successively, they jointly form a vertical wedge - shaped cut area and throw the rich ore away from the working face. After the auxiliary holes are detonated, the remaining ore in the upper - middle area of the rich ore is caved and thrown away from the working face.

[0044] (3) A differential charge structure is adopted for the empty holes, cut holes, auxiliary holes, and perimeter holes.

[0045] According to Figure 3, in the embodiment of the present application, No. 2 rock emulsion explosive is used, with a cartridge diameter of 32 mm, a length of 300 mm, and a mass of 300 g. Digital electronic detonators are used, and a special initiator for digital electronic detonators is used as the initiation power source. The digital electronic detonators are installed at the bottom of the blast holes and initiated in the reverse direction.

[0046] The bottom of the empty hole is filled with a strengthened charge package (5 cartridges) within a depth of 0.3 m, and the middle section is not blocked; The charging length of the cut holes is 1.8 m, and the stemming length is 0.7 m; The charging length of the auxiliary holes is 2.1 m, and the stemming length is 0.4 m; The charging length of the perimeter holes is 1.5 m, and the stemming length is 1.0 m.

[0047] The uncharged part of the empty hole provides a blasting free face and a compensation space for rock fragmentation for the initiation of the cut holes. The detonation of the strengthened charge package at the bottom of the empty hole throws out the rich ore within the vertical wedge cut area.

[0048] (4) Connect the empty holes, cut holes, auxiliary holes, and perimeter holes, and set the initiation sequence. Use a special initiator for digital electronic detonators to encode the digital electronic detonators, and then control the initiation sequence of the blast holes to achieve millisecond blasting.

[0049] The empty holes are initiated first, the first row of cut holes is the first blast, the Nth row of cut holes is the second blast, the auxiliary holes are the third blast, and the perimeter holes are the fourth blast.

[0050] The delay between the empty hole and the first row of cut holes is 50 ms, the delay between the first row of cut holes and the Nth row of cut holes is 50 ms, the delay between the Nth row of cut holes and the auxiliary holes is 100 ms, and the delay between the auxiliary holes and the perimeter holes is 200 ms.

[0051] (5) According to Figure 4 , after initiation, the rich ore in the middle is thrown by blasting away from the working face to form a distant muck pile, and the lean ore at the top and bottom is loosened by blasting to form an in-situ muck pile. There is a small amount of ore debris between the distant muck pile and the in-situ muck pile, which can be incorporated into the in-situ muck pile for treatment. The distant muck pile and the in-situ muck pile are shoveled and loaded separately to achieve the separation of rich and lean ores in the ore body.

[0052] After blasting, 80% of the rich ore forms a distant muck pile with an average grade of about 28.4%; 20% of the rich ore and 30% of the lean ore form intermediate debris with an average grade of about 23 - 24%; 70% of the lean ore forms an in-situ muck pile with an average grade of about 21.5%. The distance between the distant muck pile and the in-situ muck pile, that is, the length of the intermediate debris, is about 0.5 m. The technical solution of the present invention includes the following innovation points: Innovation point 1: The cut holes are inclined at 10°, which improves the throwing effect of the rich ore; if not inclined, only 50% of the rich ore can form a distant muck pile, and the remaining 50% of the rich ore will be mixed into the intermediate debris and the in-situ muck pile, greatly reducing the recovery amount of the rich ore.

[0053] Innovation Point 2: Strengthen the charge at the bottom of the empty hole to improve the throwing effect of rich ore; if the charge is not strengthened, a distinguishable distant muckpile cannot be formed, and it is difficult to distinguish the distant muckpile, the intermediate loose body, and the in-situ muckpile.

[0054] Innovation Point 3: The auxiliary holes are arranged in a ring and detonated simultaneously, increasing the amount of explosive for a single blast and improving the throwing effect of rich ore.

Claims

1. A method for separating rich and poor ore bodies in underground phosphate mines by blasting, characterized in that: The following steps are involved: (1) Determine the range of the middle rich ore, top poor ore and bottom poor ore; (2) Arrange empty holes, slot holes, auxiliary holes and peripheral holes on the working surface of the ore body, among which the empty holes, slot holes and auxiliary holes constitute the throwing blasting holes, and the peripheral holes constitute the loosening blasting holes; (3) Differentiated charge structures are used in empty holes, slot holes, auxiliary holes and peripheral holes; (4) Connect the empty holes, slot holes, auxiliary holes and peripheral holes and set the detonation sequence; (5) Detonation: The rich ore in the middle is thrown away from the working face to form a distant blast pile. The lean ore at the top and the lean ore at the bottom are loosened and blasted to form an in-situ blast pile. The distant blast pile and the in-situ blast pile are shoveled and loaded separately to achieve the separation of rich and poor ore bodies.

2. The method according to claim 1, characterized in that In the step (1), the rich ore layer satisfies a grade of ≥26.5%; the lean ore layer satisfies a grade of 24.5%>≥18%.

3. The method according to claim 1, characterized in that In step (2), an empty hole is arranged in the middle of the ore body working surface, at least two rows of slot holes are symmetrically arranged on both sides of the empty hole, auxiliary holes are arranged around the empty hole and the slot holes, and finally peripheral holes are arranged around the auxiliary holes; among the at least two rows of slot holes, the slot holes close to the empty hole are the first row, and the same is true for the Nth row of slot holes; The empty holes, slot holes and auxiliary holes are all located within the middle rich ore range; the peripheral holes are distributed in the top lean ore, bottom lean ore and middle rich ore, and surround the auxiliary holes.

4. The method according to claim 3, characterized in that The empty holes and auxiliary holes are perpendicular to the working surface, the slot holes are inclined toward the center line of the working surface, and the peripheral holes are inclined away from the center line of the working surface.

5. The method according to claim 4, characterized in that The inclination angle of the slot hole to the center line of the working surface is 5-10°, and the inclination angle of the peripheral hole away from the center line of the working surface is 3-5°.

6. The method according to claim 5, characterized in that The inclination angle of the slot hole to the center line of the working surface is 10°, and the inclination angle of the peripheral holes away from the center line of the working surface is 5°.

7. The method according to claim 1, characterized in that The hole depth is 2.3-2.8 meters, the hole diameter is 100-110 mm, and the hole spacing is 0.6-1.0 meters; The cut holes are 2.0-2.5 meters deep, 40-60 mm in diameter, and 0.6-1.0 meters apart. The auxiliary holes are 2.0-2.5 meters deep, 40-60 mm in diameter, and 0.6-1.0 meters apart; The peripheral holes have a depth of 2.0-2.5 meters, a hole diameter of 40-60 millimeters, and a hole spacing of 0.6-1.0 meters.

8. The method according to claim 7, characterized in that The bottom of the hole is filled with reinforced explosive packs within the range of 0.2-0.4 meters beyond the depth, and the middle section is not blocked; The charging length of the slot hole is 1.5-1.8 meters, and the plugging length is 0.4-0.7 meters; The auxiliary hole charging length is 1.8-2.1 meters, and the plugging length is 0.1-0.4 meters; The length of the charge in the two gang peripheral holes is 1.2-1.5 meters, and the length of the plugging is 0.7-1.0 meters; The charging length of the top and bottom peripheral holes is 1.2-1.5 meters, and the plugging length is 0.7-1.0 meter.

9. The method according to claim 8, characterized in that In step (4), the empty holes are detonated first, the first row of slot holes are detonated as the first blast, the Nth row of slot holes are detonated as the second blast, the auxiliary holes are detonated as the third blast, and the peripheral holes are detonated as the fourth blast.

10. The method according to claim 9, characterized in that The delay between the empty hole and the first row of slot holes is 30-50 milliseconds. The delay between the first row of slot holes and the Nth row of slot holes is 30-50 milliseconds, the delay between the Nth row of slot holes and the auxiliary holes is 100-500 milliseconds, and the delay between the auxiliary holes and the peripheral holes is 100-500 milliseconds.

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