Safe and efficient mining method for first mining layer in downward drift filling mining method

Abstract

The invention provides a safe and efficient mining method for a first mining layer in a downward drift filling mining method, and belongs to the field of mining, the mining method comprises the following steps: constructing a layered haulage roadway along the trend of an ore body in the first mining layer, and dividing the first mining layer into 3n stoping drifts perpendicular to the trend of the ore body; the three adjacent stoping access roads are used as units, the stoping access road located in the middle serves as a first-step stope, and the stoping access roads located on the two sides serve as second-step stopes; the method comprises the following steps: firstly, mining and supporting a first-step stope, during mining, constructing an adjacent roadway advance support anchor rod arranged along the trend of an ore body from an opening in the top of the first-step stope to a top plate of an adjacent second-step stope, and mining and supporting the second-step stope; and the length of the adjacent roadway advance support anchor rod is greater than the width of the stoping drift. According to the method, advanced pre-supporting is carried out on the second-step stope while the first-step stope is supported, continuous circulation of advanced pre-supporting and blasting in the second-step stope is reduced, the mining efficiency is greatly improved, and the supporting effect is good.

Description

Technical Field

[0001] This application relates to the technical field of mine mining, and particularly to a safe and efficient mining method for the first mining layer in the downward drift filling mining method. Background Art

[0002] In order to ensure mining safety, most medium-thick and above ore bodies with extremely broken conditions are mined by the downward drift filling mining method. When the downward drift filling mining method is actually constructed and applied, the construction of the first mining layer is particularly crucial, which is related to whether the entire drift panel can smoothly turn downward and continue mining. Under the conditions of extremely broken ore and rock, the surrounding rock has poor self-stabilizing ability. Simple shotcreting or shotcrete-bolt-net support methods cannot effectively support the construction roadway, making it difficult to ensure its safety and stability, and there are relatively large safety risks. At present, the combined support method of "advanced pre-support + shotcrete-bolt-net + steel strip + steel arch" can play a role in safely and stably supporting the stoping drifts of the first mining layer. However, before the construction of each stoping drift, active advanced pre-support needs to be carried out first to ensure its safety during the mining process, so that all stoping drifts are mined in a cycle of "advanced pre-support + blasting + secondary support in the goaf", which severely restricts the mining efficiency of the stope in the downward drift filling mining method and is difficult to achieve high-efficiency production. Summary of the Invention

[0003] In view of the technical problems existing in the background art, this application provides a safe and efficient mining method for the first mining layer in the downward drift filling mining method. The method first mines the intermediate first-step stope in a way of mining one and leaving two, and while supporting the first-step stope, conducts advanced pre-support on the second-step stope, reducing the continuous cycle of advanced pre-support and blasting in the second-step stope, and greatly improving the mining efficiency.

[0004] An embodiment of this application provides a safe and efficient mining method for the first mining layer in the downward drift filling mining method, including the following steps: S1. Construct a stratified haulage roadway arranged along the ore body strike in the first mining layer, and divide the first mining layer into 3n stoping drifts arranged perpendicular to the ore body strike, where n is an integer greater than or equal to 1; S2. Take three adjacent stoping drifts as a unit. The middle stoping drift is the first-step stope, and the stoping drifts on both sides are the second-step stopes; first mine and support the first-step stope. When mining, open an opening at the top of the first-step stope and construct a temporary roadway advanced support bolt arranged along the ore body strike towards the roof of the adjacent second-step stope, then mine and support the second-step stope; the length of the temporary roadway advanced support bolt is greater than the width of the stoping drift.

[0005] In the technical solution of the embodiment of the present application, first, the ore body of the first mining layer is divided into 3n preset stoping headings, and the middle first-step stope is mined first in the way of mining one out of every two, while the second-step stope is pre-supported in advance while the first-step stope is supported. As a result, the second-step stope adopts a cycle mode of "blasting + secondary support in the goaf", reducing the continuous cycle of advance pre-support and blasting in the second-step stope. At the same time, the switching frequency of the support device and the blasting device is greatly reduced, and the number of second-step stopes is twice that of the first-step stopes. Compared with the traditional mining method, the mining efficiency of the second-step stope in the present application is greatly improved, thereby improving the mining efficiency of the entire ore body and increasing the production capacity.

[0006] In some embodiments, the outward dip angle of the roadway advance support bolt is 5°-8°, the length of the roadway advance support bolt is 2-3 m greater than the width of the stoping heading, and the distance between adjacent roadway advance support bolts is 200-300 mm.

[0007] In this embodiment, by reasonably setting the parameters of the roadway advance support bolt, the pre-support strength of the second-step stope is improved, providing favorable conditions for the safe and efficient mining of the second-step stope.

[0008] In some embodiments, the mining and support of the first-step stope are specifically as follows: First, advance round steel bolts are constructed in the first-step stope, and then mining and support are carried out simultaneously; the support includes sequentially performing primary shotcreting, constructing cement mortar bolts, laying wire mesh, laying steel straps, secondary shotcreting, and laying steel arches in the first-step stope.

[0009] In this embodiment, the stable support of the first-step stope is realized through the support method of "advance pre-support + shotcrete, bolt and wire mesh + steel strap + steel arch", thereby realizing the safe and efficient mining of the first-step stope under the condition of extremely broken ore and rock.

[0010] In some embodiments, the mining and support of the second-step stope are specifically as follows: Mining and support are carried out simultaneously; the support includes sequentially performing primary shotcreting, constructing the cement mortar bolts, laying the wire mesh, laying the steel straps, secondary shotcreting, and laying the steel arches in the second-step stope.

[0011] In this embodiment, on the premise that the advance pre-support of the second-step stope has been formed, the stable support of the second-step stope is realized through the support method of "shotcrete, bolt and wire mesh + steel strap + steel arch", thereby realizing the safe and efficient mining of the second-step stope under the condition of extremely broken ore and rock.

[0012] In some embodiments, several first-step stopes are mined simultaneously; several second-step stopes are mined simultaneously.

[0013] In this embodiment, by simultaneously mining several first-step stopes and several second-step stopes, the mining efficiency is greatly improved.

[0014] In some embodiments, after the first-step stope is mined, it is immediately backfilled; after the second-step stope is mined, it is immediately backfilled.

[0015] In this embodiment, by immediately backfilling after the first-step stope is mined, not only the grouting process of the advanced pre-support of the first-step stope and the second-step stope is reduced, but also favorable conditions are provided for the mining of the second-step stope.

[0016] In some embodiments, before performing step S1, it further includes dividing the ore body into panels along the strike of the ore body, mining with the panel as a unit, constructing panel access roads between adjacent panels; constructing an out-of-vein haulage roadway arranged along the strike of the ore body in the surrounding rock outside the panel; after completing step S2, it further includes mining the first mining layer of the remaining panels.

[0017] In this embodiment, by reasonably dividing the panels and reasonably arranging different roadways in the panels, the production area is reasonably planned, the production system is optimized, and the mining efficiency is improved.

[0018] In some embodiments, a haulage roadway is arranged between at least one group of adjacent second-step stopes.

[0019] In this embodiment, by arranging the haulage roadway, the ore haulage route is shortened, facilitating rapid ore extraction and improving the mining efficiency.

[0020] In some embodiments, the diameter of the advanced round steel bolt is 30 - 35 mm, the length is 3.0 - 3.5 m, the circumferential spacing is 250 - 350 mm, and the outward dip angle is 3° - 5°; the thickness of the first shotcrete is 25 - 35 mm, and the strength is C15; the cement mortar bolt is arranged perpendicular to the wall surface of the stoping drift, the diameter of the cement mortar bolt is 15 - 25 mm, the length is 1.8 - 2.2 m, and the mesh size is (0.8 - 1.2) m × (0.8 - 1.2) m; the mesh size of the wire mesh is (80 - 120) mm × (80 - 120) mm, and the size is (1.8 - 2.2) m × (0.8 - 1.2) m; the steel strip is a W-shaped steel strip, the length is 2.0 - 2.5 m, the width is 200 - 250 mm, the thickness is 4 - 6 mm, and the spacing between adjacent steel strips is 0.8 - 1.2 m; the thickness of the second shotcrete is 25 - 35 mm.

[0021] In this embodiment, by reasonably setting the parameters of different support components, the safe support of the stoping drift is realized, providing favorable conditions for the safe and efficient mining of the stoping drift.

[0022] In some embodiments, step S1 further includes supporting the layered transportation roadway.

[0023] In this embodiment, by supporting the layered transportation roadway, the long-term safety and stability of the layered transportation roadway in the first mining layer are ensured, thereby providing favorable conditions for the mining of the first mining layer.

[0024] The above description is only an overview of the technical solution of the present application. In order to be able to more clearly understand the technical means of the present application, it can be implemented according to the content of the specification. And in order to make the above and other purposes, features and advantages of the present application more obvious and understandable, the specific embodiments of the present application are specifically exemplified below. Brief Description of the Drawings

[0025] In order to more clearly illustrate the technical solution of the present application, the drawings used in the present application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0026] Figure 1 Schematic diagram of the layout of the first mining layer in the panel of the downward drift backfill mining method in the embodiment of the present application; Figure 1 a is a schematic diagram of the first mining layer with 3n extraction drifts arranged; Figure 1 b is a schematic diagram of the first mining layer with 3n + 1 extraction drifts arranged; Figure 2 Full-section view of a one-step stope in the embodiment of the present application; Figure 3 Side view of a one-step stope in the embodiment of the present application; Figure 4 Front view of the support section of the extraction drift in the embodiment of the present application; Figure 5 Top view of the support section of the extraction drift in the embodiment of the present application; Figure 6 Schematic diagram of the threaded nut lapping structure in the embodiment of the present application; Figure 7 For Figure 2 Enlarged view of part A in Explanation of reference numerals: 1 - layered transportation roadway; 2 - extraction drift; 3 - pre-support bolt for adjacent roadway; 4 - pre - steel round bar bolt; 5 - cement mortar bolt; 6 - wire mesh; 7 - steel strip; 8 - steel arch; 9 - panel connection roadway; 10 - surrounding rock; 11 - out - of - vein transportation roadway; 12 - threaded nut lapping structure; 13 - transportation roadway; 14 - tray; 21 - one - step stope; 22 - two - step stope; 81 - column; 82 - arch ring; 121 - T - shaped bolt; 122 - nut; 123 - small washer; 124 - large washer. Detailed implementation manners

[0027] The embodiments of the technical solution of the present application will be described in detail below with reference to the accompanying drawings. The following embodiments are only used to illustrate the technical solution of the present application more clearly, so they are only examples and cannot be used to limit the protection scope of the present application.

[0028] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which this application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" and any variations thereof in the specification and claims of this application and the above accompanying drawings are intended to cover non-exclusive inclusion.

[0029] Referring to "embodiments" herein means that the specific features, structures or characteristics described in connection with the embodiments can be included in at least one embodiment of this application. The phrase appears in various places in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment mutually exclusive with other embodiments. Those skilled in the art will explicitly and implicitly understand that the embodiments described herein can be combined with other embodiments.

[0030] In the description of the embodiments of this application, the orientation or positional relationship indicated by technical terms such as "length", "width", "thickness", "upper", "lower", "top", "bottom", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the embodiments of this application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation to the embodiments of this application.

[0031] In the description of the embodiments of this application, unless otherwise clearly specified and limited, technical terms such as "installation", "connection", "connection", "fixation", etc. should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or integrated; it can also be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the embodiments of this application can be understood according to specific circumstances.

[0032] Most of the extremely fragmented medium-thick and above ore bodies are mined by the downward drift filling mining method. The construction of the first mining layer of the downward drift filling mining method is particularly crucial. Although the current combined support method of "advanced pre-support + shotcrete-bolt-net + steel strip + steel arch" can provide safe and stable support for the stoping drifts of the first mining layer, each stoping drift is mined by the cycle of "advanced pre-support + blasting + secondary support in the goaf", resulting in low mining efficiency.

[0033] In order to solve the technical problem of low mining efficiency caused by the cycle of "advanced pre-support + blasting + secondary support in the goaf" for each stoping drift, this application provides a safe and efficient mining method for the first mining layer in the downward drift filling mining method. First, the ore body of the first mining layer is divided into 3n stoping drifts, and the middle one-step stope is mined first by the method of mining one out of every two. While supporting the one-step stope, advanced pre-support is carried out on the two-step stope, effectively ensuring the stability of the roofs of the one-step stope and the two-step stope, and ensuring that the two-step stope has a stable roof environment before mining, so that the two-step stope adopts the cycle of "blasting + secondary support in the goaf", reducing the continuous cycle of advanced pre-support and blasting in the two-step stope. At the same time, the switching frequency of the support device and the blasting device is greatly reduced, and the number of two-step stopes is twice that of the one-step stopes. Compared with the traditional mining method, the construction efficiency of the two-step stope is improved, promoting the efficient mining of the two-step stope under the condition of extremely fragmented ore rock. This design scheme not only improves the reliability of the support effect, but also provides technical support for the efficient implementation of the downward drift filling mining method under extremely fragmented ore rock and complex geological conditions, and has broad application prospects and popularization value.

[0034] Please refer to Figures 1-7 , a safe and efficient mining method for the first mining layer in the downward drift filling mining method provided by the embodiment of the present application, includes the following steps: S1. Construct a layered haulage roadway 1 arranged along the ore body strike in the first mining layer, and divide the first mining layer into 3n stoping drifts 2 arranged perpendicular to the ore body strike, where n is an integer greater than or equal to 1. Specifically, Figure 1 the X-axis direction is along the ore body strike, and the Y-axis direction is perpendicular to the ore body strike.

[0035] S2. Take three adjacent stoping drifts 2 as a unit. The middle stoping drift 2 is the one-step stope 21, and the stoping drifts 2 on both sides are the two-step stopes 22. First, mine and support the one-step stope 21. When mining, open an opening at the top of the one-step stope 21 roadway and construct several roadway advanced support bolts 3 arranged along the ore body strike towards the roof of the adjacent two-step stope 22, and then mine and support the two-step stope 22. The length of the roadway advanced support bolt 3 is greater than the width of the stoping drift 2. As Figure 1As shown in a, the access road 201 - access road 203 form a unit, where the access road 202 is a first-step stope 21, and the access roads 201 and 203 are second-step stopes 22; the access roads 204 - access road 206 form a unit, where the access road 205 is a first-step stope 21, and the access roads 204 and 206 are second-step stopes 22, and so on. The widths of the access roads 201 - 215 are the same, that is, the cross-sections are the same; the widths of the access roads 216 - 230 are the same. Specifically, as Figure 4 and Figure 5 shown, after blasting and ore drawing for a preset distance are completed in the first-step stope 21, while supporting the goaf of the first-step stope 21, boreholes are drilled at the top position of the first-step stope 21 and the roadway advanced support bolts 3 are installed in the roof of the access roads of the two adjacent second-step stopes 22 to form the advanced pre-support of the second-step stope 22. During the mining process of the second-step stope 22, there is no need for advanced pre-support. That is, the first-step stope 21 of the present application adopts a cycle mode of "advanced pre-support + blasting + secondary support of the goaf", and the second-step stope 22 adopts a cycle mode of "blasting + secondary support of the goaf". During the mining process of the second-step stope 22, the continuous cycle of advanced pre-support and blasting is reduced. In the traditional mining method, during the mining process of each stoping access road 2, advanced borehole construction needs to be carried out first at an angle outside the excavation contour line of the stoping access road 2 and towards the arch front. After the borehole construction is completed, the advanced round steel bolts 4 are installed to form the advanced pre-support. That is, each stoping access road 2 adopts a cycle mode of "advanced pre-support + blasting + secondary support of the goaf".

[0036] In the technical solution of the embodiment of the present application, first, the ore body of the first mining layer is divided into 3n preset stoping headings 2. Three adjacent stoping headings 2 are used as a unit, and the middle first-step stope 21 is mined first in a way of mining one out of every two. While supporting the first-step stope 21, temporary roadway advanced support bolts 3 are constructed on the roofs of the two adjacent second-step stopes 22 to perform advanced pre-support on the second-step stopes 22, that is, while supporting the goaf of the first-step stope 21, advanced pre-support is directly performed on the top of the second-step stope 22. Compared with the traditional cyclic mining method of each stoping heading 2 adopting "advanced pre-support + blasting + secondary support of goaf", the temporary roadway advanced support bolts 3 constructed on both sides in the first-step stope 21 of the present application can provide effective support for the roofs of the adjacent second-step stopes 22, ensuring that the adjacent second-step stopes 22 have a stable roof environment before mining, so that the second-step stopes 22 adopt the cyclic method of "blasting + secondary support of goaf", reducing the continuous cycle of advanced pre-support and blasting in the second-step stopes 22, which helps to improve the construction efficiency of the second-step stopes 22 and thus greatly improves the mining efficiency. Secondly, the second-step stopes 22 do not need to continuously cycle advanced pre-support and blasting, greatly reducing the switching frequency of the support device and the blasting device (and since the space of the stoping heading 2 is limited, the support device needs to be removed from the stoping heading 2 during the switching process), further improving the mining efficiency. Moreover, the method of mining one out of every two in the present application makes the number of second-step stopes 22 more than that of the first-step stopes 21 (the number of second-step stopes 22 is basically twice that of the first-step stopes 21). Compared with the traditional mining method, the mining efficiency of the second-step stopes 22 in the present application is greatly improved, thus improving the mining efficiency of the entire ore body and increasing the production capacity. In addition, the advanced pre-support of the second-step stopes 22 in the present application is completed during the mining process of the first-step stope 21. Therefore, the distance advanced by the second-step stopes 22 each time increases, reducing the cycle times of "blasting + secondary support of goaf" and further improving the mining efficiency. That is, the present application improves the support and mining efficiency by optimizing the support structure and support method of the stoping headings 2 in the first mining layer, providing strong support for the efficient mining of the first mining layer under extremely broken ore-rock conditions. It can be understood that when supporting the goaf of the first-step stope 21, advanced pre-support needs to be performed on the second-step stopes 22, which will increase the mining time of the first-step stope 21. However, overall, the time shortened by the second-step stopes 22 is significantly more. Through comprehensive analysis, the method of the present application greatly improves the mining efficiency.

[0037] Further, in the embodiment of the present application, as Figure 4As shown, the outward dip angle of the advance support bolt 3 for the adjacent roadway is 5°-8°, preferably 6°; the length of the advance support bolt 3 for the adjacent roadway is 2-3 m greater than the width of the stoping drift 2, and the advance support bolt 3 for the adjacent roadway is a round steel with a diameter of 30-35 mm, preferably 32 mm; the distance between adjacent advance support bolts 3 for the adjacent roadway is 200-300 mm. Specifically, the net width of the stoping drift 2 is 3 m, and the length of the advance support bolt 3 for the adjacent roadway is 6 m.

[0038] In the technical solution of the embodiment of the present application, by reasonably setting the outward dip angle of the advance support bolt 3 for the adjacent roadway, the distance between adjacent advance support bolts 3 for the adjacent roadway, and the length of the advance support bolt 3 for the adjacent roadway, the pre-support strength of the second-step stope 22 is improved, the stability of the roof of the second-step stope 22 is ensured, and favorable conditions are provided for the safe and efficient mining of the second-step stope 22. By reasonably controlling the distance between adjacent advance support bolts 3 for the adjacent roadway, while achieving stable support for the roof of the second-step stope 22, the increase in support cost caused by the over-density of the advance support bolts 3 for the adjacent roadway is avoided.

[0039] Further, in the embodiment of the present application, as Figure 2As shown in the figure, the one-step stope 21 for mining and support is specifically as follows: First, advanced round steel bolts 4 are constructed in the one-step stope 21, and then mining and support are carried out simultaneously; the support includes spraying concrete for the first time, constructing cement mortar bolts 5, laying metal mesh 6, laying steel belts 7, spraying concrete for the second time, and laying steel arch frames 8 in the one-step stope 21 in sequence. The extraction drift 2 is a temporary construction project. After it is constructed according to the designed length, backfilling treatment is carried out immediately. Therefore, when carrying out advanced support, a non-grouting form can be adopted, and the one-step stope 21 can be normally mined according to the support method of "advanced pre-support + shotcrete with bolts and mesh + steel belt + steel arch frame". Specifically, at the opening position of the one-step stope 21, advanced drilling construction is carried out first at an out-of-angle along the excavation contour line towards the front of the arch. After the drilling construction is completed, advanced round steel bolts 4 are installed to form advanced pre-support; then mining and support are carried out simultaneously. After mining a preset distance, ventilation and mucking are carried out immediately, and then shotcrete is sprayed on the entire cross-section for the first time. After the first shotcrete is completed, drilling construction of the cement mortar bolts 5 is carried out. After the cement mortar bolts 5 are inserted into the holes, the metal mesh 6 and the steel belt 7 are laid. The steel belt 7 is arranged along the trend of the one-step stope 21, and the steel belt 7 is overlapped with the cement mortar bolts 5. Finally, a tray 14 is installed at one end of the cement mortar bolt 5 close to the one-step stope 21, so that the tray 14 presses on the metal mesh 6 and the steel belt 7, thus completing the construction of "shotcrete with bolts and mesh + steel belt"; then the second shotcrete operation is carried out to ensure that the surface of the second shotcrete layer is relatively flat, and there is basically no exposed phenomenon for the support components such as the cement mortar bolts 5, the metal mesh 6, and the steel belt 7, meeting the support safety standard; finally, the steel arch frame 8 is installed. The steel arch frame 8 includes a group of columns 81 and an arch ring 82, and a threaded nut overlapping structure 12 is provided at the connection between the column 81 and the arch ring 82; both the column 81 and the arch ring 82 are made of I-beams with a model of 25a. As Figure 6 shown in the figure, the threaded nut overlapping structure 12 includes a T-shaped bolt 121 and a nut 122. Through holes are provided at the connection between the column 81 and the arch ring 82. The T-shaped bolt 121 passes through the through holes provided on the column 81 and the arch ring 82 and is fixed by the nut 122 to realize the detachable connection between the column 81 and the arch ring 82; a large gasket 124 is provided at the contact between the T-shaped bolt 121 and the column 81; a small gasket 123 is provided at the contact between the nut 122 and the arch ring 82. After the support of the goaf in the one-step stope 21 is completed, advanced support bolts 3 arranged along the trend of the ore body are constructed at the opening at the top of the one-step stope 21 towards the roof of the adjacent two-step stope 22 to form advanced pre-support for the two-step stope 22.

[0040] In the technical solution of the embodiment of the present application, the stable support of the first-step stope 21 is realized through the support method of "advanced pre-support + shotcrete with wire mesh + steel strip + steel arch", so as to realize the safe and efficient mining of the first-step stope 21 under the condition of extremely broken ore and rock. By carrying out advanced pre-support on the second-step stope 22 during the support process of the goaf of the first-step stope 21, favorable conditions are provided for the safe and efficient mining of the second-step stope 22. By setting a threaded nut lap joint structure 12 at the connection of the column 81 and the arch ring 82, the disassembly and installation of the column 81 and the arch ring 82 are facilitated.

[0041] Further, in the embodiment of the present application, the mining and support of the second-step stope 22 are specifically as follows: mining and supporting simultaneously; the support includes successively carrying out primary shotcrete, constructing cement mortar bolts 5, laying metal mesh sheets 6, laying steel strips 7, secondary shotcrete, and laying steel arch frames 8 in the second-step stope 22. Specifically, after the second-step stope 22 is mined for a preset distance, ventilation and mucking are immediately carried out, and then primary shotcrete is carried out on the full section. After the primary shotcrete is completed, drilling construction of the cement mortar bolts 5 is carried out. After the cement mortar bolts 5 are inserted into the holes, the metal mesh sheets 6 and the steel strips 7 are laid. The steel strips 7 are arranged along the trend of the second-step stope 22, and the steel strips 7 are lapped with the cement mortar bolts 5. Finally, trays 14 are installed at one end of the cement mortar bolts 5 close to the second-step stope 22, so that the trays 14 press on the metal mesh sheets 6 and the steel strips 7, thus completing the construction of "shotcrete with wire mesh + steel strip"; then secondary shotcrete operation is carried out to ensure that the surface of the secondary shotcrete layer is relatively flat, and the support members such as the cement mortar bolts 5, the metal mesh sheets 6, and the steel strips 7 are basically not exposed, meeting the support safety standard; finally, the steel arch frames 8 are installed.

[0042] In the technical solution of the embodiment of the present application, on the premise that the advanced pre-support of the second-step stope 22 has been formed, the stable support of the second-step stope 22 is realized through the support method of "shotcrete with wire mesh + steel strip + steel arch", so as to realize the safe and efficient mining of the second-step stope 22 under the condition of extremely broken ore and rock.

[0043] Further, in the embodiment of the present application, several first-step stopes 21 are mined simultaneously; several second-step stopes 22 are mined simultaneously.

[0044] In the technical solution of the embodiment of the present application, by mining several first-step stopes 21 simultaneously and mining several second-step stopes 22 simultaneously, the mining efficiency is greatly improved.

[0045] Further, in the embodiment of the present application, backfilling is carried out immediately after the first-step stope 21 is mined; backfilling is carried out immediately after the second-step stope 22 is mined.

[0046] In the technical solution of the embodiment of the present application, by filling immediately after the first-step stope 21 and the second-step stope 22 are mined out, not only the grouting process of the advanced pre-support of the first-step stope 21 and the second-step stope 22 is reduced, but also favorable conditions are provided for the mining of the second-step stope 22, realizing the efficient and safe mining of the second-step stope 22.

[0047] Further, in the embodiment of the present application, as Figure 1 shown, before performing step S1, it further includes dividing the ore body into panels along the ore body strike, mining with the panel as a unit, and constructing panel access roads 9 between adjacent panels; constructing an off-vein haulage roadway 11 arranged along the ore body strike in the surrounding rock 10 outside the panel; and after completing step S2, it further includes mining the first mining layer of the remaining panels. It can be understood that before mining, it is necessary to construct in advance mining preparation and cutting projects such as the main ore haulage roadway and the return airway to ensure the circulation of fresh air flow during the mining process and the smooth transportation of ore. These mining preparation and cutting projects are conventional settings for the downward drift filling mining method and will not be elaborated here.

[0048] In the technical solution of the embodiment of the present application, by reasonably dividing the panels and reasonably arranging different roadways in the panels, the production area is reasonably planned, the production system is optimized, and the mining efficiency is improved.

[0049] Further, in the embodiment of the present application, as Figure 1 shown, a haulage roadway 13 is arranged between at least one group of adjacent second-step stopes 22. Specifically, the haulage roadway 13 is arranged in the ore body on one side close to the off-vein haulage roadway 11. Ore is transported to the off-vein haulage roadway 11 for ore drawing through the stratified haulage roadway 1, the panel access road 9, and the haulage roadway 13. As Figure 1 shown in a, after the haulage roadway 13 is set, in order to divide the first mining layer into 3n stoping drifts 2, the widths of drifts 201 - 215 are the same, the widths of drifts 216 - 230 are the same, and the widths of drifts 216 - 230 are slightly larger than the widths of drifts 201 - 215. As Figure 1 shown in b, after the haulage roadway 13 is set, if it is necessary to ensure that the widths of all the stoping drifts 2 are the same, at this time, drift 231 is mined as the first-step stope 21.

[0050] In the technical solution of the embodiment of the present application, by arranging a haulage roadway 13 between at least one group of adjacent second-step stopes 22, the ore transportation route is shortened, facilitating rapid ore drawing and improving the mining efficiency.

[0051] Further, in the embodiment of the present application, as Figure 2As shown in the figure, the diameter of the advanced round steel bolt 4 in the stope 21 of one step is 30-35 mm, the length is 3.0-3.5 m, the circumferential spacing is 250-350 mm, and the outward dip angle is 3°-5°. Preferably, the diameter of the advanced round steel bolt 4 is 32 mm, the length is 3 m, the circumferential spacing is 300 mm, and the outward dip angle is 4°. The thickness of the first shotcrete for all the stoping headings 2 is 25-35 mm, preferably 30 mm, and the strength is C15. The cement mortar bolt 5 is arranged perpendicular to the wall surface of the stoping heading 2. The diameter of the cement mortar bolt 5 is 15-25 mm, the length is 1.8-2.2 m, and the mesh size is (0.8-1.2) m × (0.8-1.2) m. Preferably, the diameter of the cement mortar bolt 5 is 20 mm, the length is 2 m, and the mesh size is 1 m × 1 m. The mesh size of the metal mesh 6 is (80-120) mm × (80-120) mm, and the size is (1.8-2.2) m × (0.8-1.2) m. Preferably, the mesh size of the metal mesh 6 is 100 mm × 100 mm, and the size is 2 m × 1 m. The metal mesh 6 is welded by steel bars with a diameter of 8 mm. The steel strip 7 is a W-shaped steel strip, with a length of 2.0-2.5 m, a width of 200-250 mm, and a thickness of 4-6 mm. Preferably, the length of the steel strip 7 is 2 m, the width is 220 mm, and the thickness is 5 mm. The spacing between adjacent steel strips 7 is 0.8-1.2 m, preferably 1 m. In the locally more fractured area, the spacing between adjacent steel arches 8 can be appropriately reduced, and the arch ring 82 is processed according to the arched shape of the stoping heading 2. The thickness of the second shotcrete is 25-35 mm. The distance (i.e., the step distance) between adjacent steel arches 8 is 0.8-1.2 m, preferably 1 m.

[0052] In the technical solution of the embodiment of the present application, by reasonably setting the parameters of the advanced round steel bolt 4, the cement mortar bolt 5, the metal mesh 6, the steel strip 7, the first shotcrete and the second shotcrete, the safe support of the stoping heading 2 is realized, providing favorable conditions for the safe and efficient mining of the stoping heading 2. By reasonably controlling the distance between adjacent steel arches 8, while achieving stable support, the over-density of the steel arches 8 is avoided, thus increasing the support cost.

[0053] Further, in the embodiment of the present application, step S1 further includes the support of the stratified transportation roadway 1. Specifically, at the opening position of the stratified transportation roadway 1, advanced drilling construction is first carried out along the outside of the excavation contour line at an out-of-plane angle towards the arch front. After the drilling construction is completed, advanced grouting bolts are installed to form advanced pre-support, and then grouting construction is carried out. After the slurry solidifies, the excavation operation of the stratified transportation roadway 1 is carried out; immediately after the excavation of the stratified transportation roadway 1, ventilation and mucking are carried out, and then shotcrete operation is carried out on the entire cross-section at one time; after the one-time shotcrete is completed, the drilling construction of the cement mortar bolts 5 is carried out. After the cement mortar bolts 5 are inserted into the holes, the metal mesh 6 and steel strips 7 are laid. The steel strips 7 are arranged along the trend of the stratified transportation roadway 1, and the steel strips 7 are lapped with the cement mortar bolts 5, thus completing the construction of "shotcrete, bolt, mesh + steel strip"; then the secondary shotcrete operation is carried out to ensure that the surface of the secondary shotcrete layer is relatively flat, and the support members such as the cement mortar bolts 5, the metal mesh 6 and the steel strips 7 are basically not exposed, meeting the support safety standard; then the steel arch 8 is installed, and the size of the steel arch 8 is set according to the size of the stratified transportation roadway 1. The advanced grouting bolt is a hollow seamless steel pipe, the outer diameter of the advanced grouting bolt is 30 - 35 mm, the wall thickness is 5 - 7 mm, the length is 3.0 - 3.5 m, the circumferential spacing is 250 - 350 mm, and the out-of-plane angle is 3° - 5°. Preferably, the outer diameter of the advanced grouting bolt is 32 mm, the wall thickness is 6 mm, the length is 3 m, and the circumferential spacing is 300 mm, and the out-of-plane angle is 4°.

[0054] In the technical solution of the embodiment of the present application, the combined support method of "advanced grouting + full-section shotcrete, bolt, mesh + steel strip + steel arch" is adopted to support the stratified transportation roadway 1 of the first mining layer. This support method has good active support effect and large support strength, and can ensure the long-term safety and stability of the stratified transportation roadway 1 of the first mining layer.

[0055] Please refer to Figures 1 to 7 , according to one or more embodiments of the present application, the present application first divides the ore body of the first mining layer into 3n extraction headings 2, takes three adjacent extraction headings 2 as a unit, and first mines the intermediate first-step stope 21 in a way of mining one out of every two. While supporting the first-step stope 21, advanced pre-support is carried out on the two adjacent second-step stopes 22, so that the second-step stopes 22 adopt a cycle mode of "blasting + secondary support in the goaf", reducing the continuous cycle of advanced pre-support and blasting in the second-step stopes 22. At the same time, the switching frequency of the support device and the blasting device is greatly reduced, and the number of the second-step stopes 22 is twice that of the first-step stopes 21. This method not only improves the reliability of the support effect, but also greatly improves the mining efficiency of the second-step stopes 22, thereby improving the mining efficiency of the entire ore body and increasing the production capacity.

[0056] The present invention will be described in detail below through specific embodiments.

[0057] Example 1 A method for safe and efficient mining of the first mined layer in a downward drift filling mining method, comprising the following steps: S1. As shown in Figure 1 a, a stratified haulage roadway 1 arranged along the ore body strike is constructed in the first mined layer, and the first mined layer is divided into 30 stoping drifts 2 arranged perpendicular to the ore body strike.

[0058] S2. Taking three adjacent stoping drifts 2 as a unit, the middle stoping drift 2 is the first-step stope 21, and the stoping drifts 2 on both sides are the second-step stopes 22. Specifically, drifts 201 - 203 are a unit, where drift 202 is the first-step stope 21, and drifts 201 and 203 are the second-step stopes 22; drifts 204 - 206 are a unit, where drift 205 is the first-step stope 21, and drifts 204 and 206 are the second-step stopes 22, and so on, divided into 10 units.

[0059] First, the first-step stope 21 is mined and supported. During mining, several temporary roadway advanced support bolts 3 arranged along the ore body strike are constructed by opening at the top of the drift in the first-step stope 21 towards the roof of the adjacent second-step stope 22, and then the second-step stope 22 is mined and supported. Specifically, the gross section size of drifts 201 - 215 is 3.8m×3.3m, and the net section size after support is 3.2×3.0m; the gross section width and net section width of drifts 216 - 230 are slightly wider than those of drifts 201 - 215, and the gross section height and net section height of drifts 216 - 230 are the same as those of drifts 201 - 215.

[0060] The diameter of the advanced round steel bolt 4 in the first-step stope 21 is 32 mm, the length is 3 m, the circumferential spacing is 300 mm, the outward dip angle is 4°, and the opening spacing of the advanced round steel bolt 4 is 2 m. The outward dip angle of the roadway advanced support bolt 3 in the second-step stope 22 is 6°, and the roadway advanced support bolt 3 is a round steel with a diameter of 32 mm. The distance between adjacent roadway advanced support bolts 3 is 300 mm, and the length of the roadway advanced support bolt 3 is 6 m (since the width of the access roads 216 - 230 is slightly larger than that of the access roads 201 - 215, the lengths of all the advanced support bolts 3 used in the second-step stope 22 are the same, reducing the manufacturing difficulty of different advanced support bolts 3). The estimated time required to mine 30 20-m long stoping access roads 2 in this application is 360 days, and the estimated bolt cost of the advanced round steel bolts 4 and the roadway advanced support bolts 3 used is 300,000 yuan. The support stability of both the first-step stope 21 and the second-step stope 22 is relatively good during the entire stoping process. It can be understood that different panels can be mined simultaneously to shorten the time required to mine the entire ore body. The setting of the support parameters during the mining process depends on the specific mine.

[0061] If the stoping is carried out according to the traditional method, that is, all the stoping access roads 2 adopt the cycle mode of "advanced pre-support + blasting + secondary support of the goaf", and the alternate mining method is used. First, the first-step stope 21 is mined, and then the second-step stope 22 is mined. The estimated time required to mine 30 20-m long stoping access roads 2 is 470 days, and the estimated bolt cost of the advanced round steel bolts 4 used is 370,000 yuan.

[0062] It should be noted that this application is not limited to the above embodiments. The above embodiments are only examples, and embodiments with the same structure and the same function and effect as the technical idea within the scope of the technical solution of this application are all included in the technical scope of this application. In addition, within the scope of not departing from the main idea of this application, various deformations that can be thought of by those skilled in the art to the embodiments, and other ways constructed by combining some of the constituent elements in the embodiments are also included in the scope of this application.

Claims

1. A safe and efficient mining method for the first mining layer in a downward approach filling mining method, characterized in that: The following steps are involved: S1. Construct a layered transportation tunnel arranged along the direction of the ore body in the primary mining layer, and divide the primary mining layer into 3n mining access roads arranged perpendicular to the direction of the ore body, where n is an integer greater than or equal to 1; S2. Taking the three adjacent mining approaches as a unit, the mining approach located in the middle is a one-step stope, and the mining approaches located on both sides are two-step stopes; firstly, the one-step stope is mined and supported, and during mining, an opening is opened at the top of the one-step stope to construct an adjacent advance support anchor rod along the direction of the ore body toward the roof of the adjacent two-step stope, and the two-step stope is mined and supported; the length of the advance support anchor rod adjacent to the stope is greater than the width of the mining approach.

2. The method for safe and efficient mining of the first mining layer in the downward approach filling mining method according to claim 1 is characterized in that: The external insertion angle of the advance support anchor rod adjacent to the tunnel is 5°-8°, the length of the advance support anchor rod adjacent to the tunnel is 2-3m larger than the width of the mining access road, and the distance between adjacent advance support anchor rods adjacent to the tunnel is 200-300mm.

3. The method for safe and efficient mining of the first mining layer in the downward approach filling mining method according to claim 1 is characterized in that: The specific method of mining and supporting the first-step mining site is as follows: first, an advanced round steel anchor is constructed in the first-step mining site, and then mining and supporting are performed simultaneously; the support includes sequentially spraying concrete once, constructing cement mortar anchors, laying metal meshes, laying steel belts, spraying concrete twice, and laying steel arch frames in the first-step mining site.

4. The method for safe and efficient mining of the first mining layer in the downward approach filling mining method according to claim 3 is characterized in that: Mining and supporting the two-step mining site specifically includes: mining and supporting at the same time; the support includes sequentially carrying out a shotcrete spraying, constructing the cement mortar anchor rods, laying the metal mesh, laying the steel belt, a second shotcrete spraying, and laying the steel arch frame in the two-step mining site.

5. The method for safe and efficient mining of the first mining layer in the downward approach filling mining method according to claim 4 is characterized in that: Several of the first-step mining areas are mined simultaneously; several of the second-step mining areas are mined simultaneously.

6. The method for safe and efficient mining of the first mining layer in the downward approach filling mining method according to claim 5 is characterized in that: After the mining in the first step is completed, the stope is immediately backfilled; after the mining in the second step is completed, the stope is immediately backfilled.

7. The method for safe and efficient mining of the first mining layer in the downward approach filling mining method according to claim 1 is characterized in that: Before performing step S1, the process also includes dividing the ore body into panels along the direction of the ore body, mining the panels as units, and constructing panel connecting roads between adjacent panels; constructing extra-vein transport tunnels arranged along the direction of the ore body in the surrounding rock outside the panels; and after completing step S2, the process also includes mining the first mining layers of the remaining panels.

8. The method for safe and efficient mining of the first mining layer in the downward approach filling mining method according to claim 7 is characterized in that: A transport path is arranged between at least one set of adjacent two-step stopes.

9. The method for safe and efficient mining of the first mining layer in the downward approach filling mining method according to claim 4 is characterized in that: The diameter of the advanced round steel anchor rod is 30-35mm, the length is 3.0-3.5m, the circumferential spacing is 250-350mm, and the external insertion angle is 3°-5°; the thickness of the one-time shotcrete is 25-35mm, and the strength is C15; the cement mortar anchor rod is arranged perpendicular to the wall of the mining access road, the diameter of the cement mortar anchor rod is 15-25mm, the length is 1.8-2.2m, and the mesh size is (0.8-1.2)m× (0.8-1.2)m; the mesh size of the metal mesh is (80-120)mm×(80-120)mm, and the size is (1.8-2.2)m×(0.8-1.2)m; the steel belt is a W-shaped steel belt with a length of 2.0-2.5m, a width of 200-250mm, a thickness of 4-6mm, and a spacing between adjacent steel belts of 0.8-1.2m; the thickness of the secondary sprayed concrete is 25-35mm.

10. The method for safe and efficient mining of the first mining layer in the downward approach filling mining method according to claim 1, characterized in that: Step S1 also includes supporting the layered transport tunnel.

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