Method for determining the mining sequence of steeply dipping, thick phosphate rock layers with interlayers

Abstract

This invention belongs to the field of phosphate deposit mining design, specifically involving a method for determining the mining sequence of steeply dipping, thick phosphate ore layers with interlayers. This includes obtaining comprehensive strength indices for each stratum based on its thickness and strength, wherein the ore layer thickness is selected from the thickness of a single blast; if K j Mining layer b first, then blasting interlayers and backfilling; mining layer a and backfilling; if K a Mining layer a first and then filling it, followed by mining layer b and filling it; if K b Minimum, mine layer b first, and at K a Stronger than K j The interlayer is blasted and filled; the a-seam is mined and filled. This invention establishes a comprehensive strength index to compare the strength of two ore layers, interlayers, and the roof. This comprehensive strength index is particularly suitable for guiding the mining sequence, mining direction, and selection of interlayer retention or removal. This invention can ensure mining safety to the greatest extent.

Description

Technical Field

[0001] This invention belongs to the field of phosphate deposit mining design, specifically relating to a method for determining the mining sequence of thick, steeply dipping phosphate strata containing interlayers. Background Technology

[0002] The Weng'an Daxin Beidoushan phosphate mine is rich in two ore layers, A and B. The ore body has a total strike length of 190m and a dip depth of 240m, with a dip angle of 55° to 70° at depth, forming a steeply dipping ore layer. Both ore layers A and B are thick ore bodies. There is a distinct interlayer between ore layers A and B, mainly composed of phosphate dolomite interbedded with phosphate-bearing carbonaceous mudstone, with an average thickness of 3.83m. Due to the small thickness of the interlayer, i.e., the small distance between ore layers A and B, ore layers A and B are mined simultaneously, specifically using the upward segmented open-cut followed by backfilling mining method.

[0003] Currently, the mine has completed the mining of the 1020 and 1080 sections, employing a method of preserving interlayers and mining the A-seam first, followed by the B-seam. However, if the interlayer is thin and weak, it is prone to breakage, impacting safe mining operations, especially when mining the A-seam first from the interlayer towards the floor. Furthermore, the strength and thickness of the top and bottom plates of the ore seam also affect safe mining operations.

[0004] Therefore, due to the influence of changes in interlayer thickness and strength, the problems of how to treat the interlayer (such as preservation or blasting), and how to simultaneously consider the strength of the top and bottom plates to determine the mining sequence and mining direction of ore layer A and ore layer B, so as to maximize mining safety, need to be solved. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention proposes a method for determining the mining sequence of steeply dipping, thick phosphate rock layers containing interlayers, comprising the following steps:

[0006] S1: Obtain the comprehensive strength index K of the top plate and interlayer based on the formation thickness and strength, respectively. d K j The comprehensive strength index K of ore layers b and a was obtained based on the thickness and intensity of a single blast. b K a ;

[0007] S2: Compare K a K b K j ;

[0008] S3: If K j The minimum is to first mine and transport out the B ore layer; then blast the interlayer without transporting it out, and subsequently fill the B ore layer and the voids created by mining the interlayer with a mixture of filling material and blasted interlayer gravel; finally, mine and transport out the A ore layer, and then fill it with filling material.

[0009] S4: If K a Minimum; mine ore layer a, transport it out, and then backfill it with backfill material; mine ore layer b and transport it out, and then backfill it with backfill material;

[0010] S5: If K b Minimum, mine layer b first;

[0011] S51: If K j Stronger than K a Mining and transporting ore layer b, followed by backfilling with backfill material; mining and transporting ore layer a, followed by backfilling with backfill material.

[0012] S52: If K a Stronger than K j First, mine and transport out the B ore layer; then blast the interlayer without transporting it out, and subsequently fill the empty areas created by mining the B ore layer and the interlayer with a mixture of filling material and blasted interlayer crushed stone; finally, mine and transport out the A ore layer, and subsequently fill it with filling material.

[0013] Preferably, in step S1, the comprehensive strength index is determined by the product of thickness and strength.

[0014] Preferably, in step S1, the strength is selected from the uniaxial compressive strength index.

[0015] Preferably, in steps S3, S4, S51, and S52, if K d K greater than a certain multiple b Mining layer B from top to bottom, or from bottom to top.

[0016] Preferably, in steps S3, S4, S51, and S52, the filling material is a cemented filling material.

[0017] Preferably, in steps S3 and S52, the a-sediment is mined from top to bottom.

[0018] Preferably, in steps S4 and S51, the a-sediment is mined from bottom to top.

[0019] Preferably, the segmented open-cut and subsequent backfilling mining method is used to mine the seam.

[0020] Preferably, the mining layer is mined using the upward segmented open space followed by backfilling method.

[0021] Beneficial technical effects: This invention establishes a comprehensive strength index to compare the strength of two ore layers, interlayers, and the roof. This comprehensive strength index is particularly suitable for guiding the mining sequence, mining direction, and selection of interlayer retention or removal. This invention can ensure mining safety to the greatest extent. Attached Figure Description

[0022] Figure 1 This is a schematic cross-sectional view of the occurrence of phosphate rock ore layers according to the present invention.

[0023] Figure 2 Schematic diagram of the dip profile for the upward segmented open space subsequent backfilling mining method;

[0024] Figure 3 Schematic diagram of the strike profile for the upward segmented open space subsequent backfilling mining method;

[0025] In the diagram, a-ore layer; b-ore layer; interlayer 1, top plate 2, bottom plate 3, first section 41, second section 42, third section 43, intermediate transport roadway 5, segmented transport roadway 6, rock drilling ore extraction roadway 7, blasting hole 8, first-step stope 91, second-step stope 92. Detailed Implementation

[0026] The following example uses the Daxin Beidoushan phosphate mine in Weng'an County, combined with the attached... Figure 1-3 The present invention will be further described below.

[0027] like Figure 1-3 As shown, the Weng'an Daxin Beidoushan phosphate mine area is rich in two ore layers, a and b, which are steeply dipping ore layers. The ore body has a total strike length of 190m and a dipping depth of 240m. Between ore layers a and b, there is a distinct interlayer 1, mainly composed of phosphate dolomite interbedded with phosphate-bearing carbonaceous mudstone, with an average thickness of 3.83m. Due to the relatively small thickness of interlayer 1, i.e., the small distance between ore layers a and b, both ore layers a and b are mined simultaneously, specifically using the upward segmented open-cut followed by backfilling mining method. However, if interlayer 1 is thin and has low strength, it is prone to breakage, affecting the safe mining of the ore layer, especially when ore layer a is mined first from interlayer 1 towards the bottom plate 3. Furthermore, the strength and thickness of the roof plate 2 and the bottom plate 3 also affect the safe mining of the ore layer.

[0028] Therefore, due to the influence of the thickness and strength of interlayer 1, the problems of how to treat interlayer 1 (such as preservation or blasting), and how to simultaneously consider the strength of the roof 2 and the floor 3 to determine the mining sequence and mining direction of ore layer a and ore layer b, so as to maximize the mining safety, need to be solved.

[0029] Before introducing the specific technical solution of this invention, a brief introduction to the upward segmented open space subsequent filling mining method will be given (this technology is prior art, and will only be briefly introduced in this article without further elaboration); such as Figure 1-3As shown, for a certain middle section, its vertical height is 45m. This middle section is divided into three segments along its height: segment 41 (bottom), segment 42 (bottom), and segment 43 (top). The designed mining thickness within this middle section includes the entire thickness of ore layers a and b. At the same level below each segment, a segmental transport roadway 6 is constructed along the strike, outside the roof 2 and the floor 3. Similarly, at the same level above the third segment 43, a segmental transport roadway 6 is constructed along the strike, outside the roof 2 and the floor 3. The first segment... The segmented transport roadway 6 also serves as the transport roadway for the entire middle section, and can also be called the middle section transport roadway 5. Each segment is divided into several ore chambers along the strike, with each ore chamber being approximately 15m wide. For each ore chamber, a horizontal drilling roadway 7 is constructed at the bottom of the ore layer to connect the segmented transport roadway 6 at the corresponding positions on the outer side of the roof 2 and the outer side of the floor 3. For each ore chamber in the third segment 43, a horizontal drilling roadway 7 is constructed at the top of the ore layer to connect the segmented transport roadway 6 at the corresponding positions on the outer side of the roof 2 and the outer side of the floor 3.

[0030] The mining and filling of the three sections are carried out sequentially from bottom to top. The mining and filling of each section is carried out as follows: a stope is selected, and several rows of fan-shaped blasting holes 8 are constructed from the rock drilling and ore extraction roadway 7 above it along the thickness direction of the ore layer. One row is blasted at a time. The ore after blasting is transported out from the rock drilling and ore extraction roadway 7 below the stope to the section transport roadway 6. When the ore in the entire thickness direction of the stope is mined out (or whenever the ore in the entire thickness direction of one layer of ore is mined out), the voids created by mining are filled.

[0031] In addition, each segment of the stope can be alternately divided into a first-step stope 91 and a second-step stope 92 along the strike. The first-step stope 91 is mined and filled first, and then the second-step stope 92 is mined and filled. This is a well-known mining method in the art and will not be described in detail here.

[0032] The downward segmented open-stope mining method involves mining each segment in the middle section from top to bottom, and its mining method is consistent with that of the upward segmented open-stope mining method.

[0033] In response to the above problems, such as Figure 1-3 As shown, based on the segmented open-cut subsequent filling mining method, especially the upward segmented open-cut filling mining method, this invention proposes a method for determining the mining sequence of steeply dipping thick phosphate rock layers containing interlayers, which is particularly suitable for steeply dipping rock layers, including the following steps:

[0034] S1: Obtain the comprehensive strength index of adjacent strata, which includes the top plate 2, ore layer b, interlayer 1, ore layer a and bottom plate 3 from top to bottom. The comprehensive strength index refers to an index that can reflect the thickness and strength of the strata. For strata other than ore layer a and ore layer b, such as top plate 2, interlayer 1 and bottom plate 3, the index is obtained by multiplying the thickness of the strata by the strata strength index (such as uniaxial compressive strength). For ore layer a and ore layer b, the index is obtained by multiplying the thickness of the ore layer in a single blast by the strata strength index (such as uniaxial compressive strength). For example, several rows of fan-shaped blasting holes 8 will be drilled along the thickness direction of the ore layer for blasting and ore extraction. The thickness of the ore layer that can be blasted by one or several rows of blasting holes at the same time is used to calculate the comprehensive strength index of ore layer a and ore layer b.

[0035] S2: Compare the comprehensive strength indices of ore layer a, ore layer b, and interlayer 1;

[0036] S3: If the comprehensive strength index K of interlayer 1 j Minimum;

[0037] S31: The b ore layer is located on the upper side of the relative top plate of interlayer 1. Therefore, the b ore layer should be mined first. After the b ore layer is mined, interlayer 1 will not be suspended and there is no risk of collapse; at most, it may partially detach. However, if the a ore layer is mined first, since interlayer 1 is located on the relative top plate side of the a ore layer, the bottom plate side of interlayer 1 will be unsupported after the a ore layer is mined, leaving it in a suspended state and prone to collapse. This will have a safety impact on the mining of the a ore layer, and the comprehensive strength index K of the a ore layer will also be affected. a The comprehensive strength index K of the interlayer is greater than that of the interlayer. j The energy required for mining can also easily damage interlayer 1;

[0038] Furthermore, if the comprehensive strength index K of the top plate 2... d The comprehensive strength index K of the b ore layer is greater than 1.5 times. b Mining and transporting the b ore layer from top plate 2 towards bottom plate 3; otherwise, mining and transporting the b ore layer from bottom plate 3 towards top plate 2; blasting interlayer 1 without transporting it, and subsequently filling the voids created by mining the b ore layer and interlayer 1 with cemented backfill material mixed with the blasted interlayer crushed rock; the comprehensive strength index K of top plate 2. d The comprehensive strength index K of the b ore layer is greater than b When mining the b ore layer, the disturbance caused is small. It is preferable to mine the b ore layer from the top plate 2 to the bottom plate 3. Since the top plate 2 is located on the top side of the b ore layer, the top plate 2 will be suspended after the b ore layer is mined, and it is easily affected by its own weight, resulting in bending deformation or even damage. Therefore, a certain safety factor is adopted, such as 1.5 times the comprehensive strength index K of the top plate in this embodiment. d Comprehensive strength index K of ore layer b b Compare;

[0039] S32: At this point, for the a-layer, the subsequent filling body of the b-layer and the interlayer has a large comprehensive strength index due to its large thickness. There is no need to consider the comprehensive strength index of the bottom plate 3. The a-layer can be mined and transported out from the top plate 2 to the bottom plate 3, and cemented filling material can be used for subsequent filling.

[0040] S4: If the comprehensive strength index K of ore layer a a Minimum;

[0041] S41: Mining the a ore layer from bottom plate 3 to top plate 1, transporting it out, and then backfilling it with cemented backfill material; mining the a ore layer from bottom plate 3 to top plate 1 can reduce the exposure time of interlayer 1, reduce the danger of mining the a ore layer, and also facilitate the later mining of the b ore layer; even if the comprehensive strength index of bottom plate 3 is weaker than that of the a ore layer, it will not be exposed because it is located on the relatively bottom side of the a ore layer, and the danger is very low.

[0042] S42: Mining ore layer b, at which point interlayer 1 is not at risk of collapse;

[0043] If the comprehensive strength index K of the top plate 2 d The comprehensive strength index K of the b ore layer is greater than 1.5 times. b Mining and transporting the b ore layer from top plate 2 towards bottom plate 3; otherwise, mining and transporting the b ore layer from bottom plate 3 towards top plate 2; subsequent backfilling using cemented backfill material; the comprehensive strength index K of top plate 2. d The comprehensive strength index K of the b ore layer is greater than b At that time, the disturbance caused by mining the b ore layer is small, so mining the b ore layer from the top plate 2 to the bottom plate 3 can be preferred. Since the top plate 2 is located on the opposite side of the b ore layer, the top plate 2 will be suspended after the b ore layer is mined, and is easily affected by its own weight, resulting in bending deformation or even failure. Therefore, a certain safety factor is taken, that is, 1.5 times the comprehensive strength index K of the top plate is required. d Comprehensive strength index K of ore layer b b Compare;

[0044] S5: If the comprehensive strength index K of the b ore layer b Minimum; mine layer b first;

[0045] S51: If the comprehensive strength index K of interlayer 1 j The comprehensive strength index K is stronger than that of ore layer A. a ;

[0046] S511: If the comprehensive strength index K of the top plate 2 d The comprehensive strength index K of the b ore layer is greater than 1.5 times. b Mining and transporting the b ore layer from the top plate 2 to the bottom plate 3, or mining and transporting the b ore layer from the bottom plate 3 to the top plate 2; cemented backfill material is used for subsequent backfilling; the reason for selecting the mining direction is the same as S42;

[0047] S512: Mining the a ore layer from bottom plate 3 to top plate 1, transporting it out, and then backfilling it with cemented backfill material; mining the a ore layer from bottom plate 3 to top plate 1 can reduce the exposure time of interlayer 1, reduce the danger of mining the a ore layer, and also facilitate the later mining of the b ore layer; even if the comprehensive strength index of bottom plate 3 is weaker than that of the a ore layer, it will not be exposed because it is located on the relatively bottom side of the a ore layer, and the danger is very low.

[0048] S52: If the comprehensive strength index K of ore layer a a The overall strength index K is stronger than that of interlayer 1. j ;

[0049] S521: If the comprehensive strength index K of the top plate 2 d The comprehensive strength index K of the b ore layer is greater than 1.5 times. b Mining layer B from top plate 2 towards bottom plate 3 and transporting it out; otherwise, mining layer B from bottom plate 3 towards top plate 2 and transporting it out. Blasting interlayer 1 without transporting it out, and subsequently filling the voids created by mining layer B and interlayer 1 with cemented backfill material mixed with the blasted interlayer rubble. Before mining layer A, interlayer 1, whose comprehensive strength index is weaker than that of layer A, is mined (treated) to prevent the collapse of interlayer 1 during the mining of layer A from affecting the safety of layer A mining. Specifically, since interlayer 1 is located on the opposite top plate side of layer A, after the mining of layer A, the bottom plate side of interlayer 1 is unsupported and in a suspended state, making it prone to collapse and affecting the safety of layer A mining. Furthermore, the comprehensive strength index K of layer A... a The comprehensive strength index K of the interlayer is greater than that of the interlayer. j The energy required for mining can also easily damage interlayer 1;

[0050] S522: At this point, for the a-layer, the subsequent filling of the b-layer and interlayer 1 has a large comprehensive strength index due to its large thickness. There is no need to consider the comprehensive strength index of the bottom plate 3. The a-layer can be mined and transported out from the top plate 2 to the bottom plate 3, and cemented filling material can be used for subsequent filling.

[0051] This invention is not limited to the preferred embodiments described above. Anyone can derive other methods in various forms under the guidance of this invention. Any technical solution that is the same as or similar to this application falls within the protection scope of this invention.

Claims

1. A method for determining the mining sequence of a steeply dipping, thick phosphate rock layer containing interlayers, characterized in that, Includes the following steps: S1: Obtain the comprehensive strength index K of the top plate and interlayer based on the formation thickness and strength, respectively. d K j The comprehensive strength index K of ore layers b and a was obtained based on the thickness and intensity of a single blast. b K a ; S2: Compare K a K b K j ; S3: If K j The minimum is to first mine and transport out the B ore layer; then blast the interlayer without transporting it out, and subsequently fill the B ore layer and the voids created by mining the interlayer with a mixture of filling material and blasted interlayer gravel; finally, mine and transport out the A ore layer, and then fill it with filling material. S4: If K a Minimum; mine ore layer A from bottom to top, transport it out, and then backfill it with backfill material; mine ore layer B and transport it out, and then backfill it with backfill material; S5: If K b Minimum, mine layer b first; S51: If K j Stronger than K a Mining and transporting ore layer b, followed by backfilling with backfill material; mining and transporting ore layer a from bottom to top, followed by backfilling with backfill material; S52: If K a Stronger than K j First, mine and transport out the B ore layer; then blast the interlayer without transporting it out, and subsequently fill the empty areas created by mining the B ore layer and the interlayer with a mixture of filling material and blasted interlayer crushed stone; finally, mine and transport out the A ore layer, and subsequently fill it with filling material.

2. The sampling sequence determination method according to claim 1, characterized in that, In step S1, the comprehensive strength index is determined by the product of thickness and strength.

3. The sampling sequence determination method according to claim 2, characterized in that, In step S1, the strength is selected based on the uniaxial compressive strength index.

4. The sampling sequence determination method according to claim 1, characterized in that, In steps S3, S4, S51, and S52, if K d K greater than a certain multiple b Mining layer B from top to bottom, or from bottom to top.

5. The sampling sequence determination method according to claim 4, characterized in that, In steps S3, S4, S51, and S52, the filling material is selected as a cemented filling material.

6. The sampling sequence determination method according to claim 5, characterized in that, In steps S3 and S52, the a ore layer is mined from top to bottom.

7. The sampling sequence determination method according to claim 6, characterized in that, In steps S4 and S51, the a-sediment is mined from bottom to top.

8. The sampling sequence determination method according to any one of claims 1-7, characterized in that, The segmented open-pit mining method followed by backfilling was used to mine the ore layer.

9. The sampling sequence determination method according to any one of claims 1-7, characterized in that, The ore layer was mined using the upward segmented open space followed by backfilling method.

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