Method for replacing the mechanical environment of a clay layer reshaped pillar

Abstract

The present application relates to a kind of methods for replacing clay layer remolding ore pillar mechanical environment, comprising the following steps: for a kind of clay layer containing ore pillar, ore pillar includes lean ore layer, clay layer, rich ore layer, by using broken stone+ thin concrete mortar replaces clay layer part, the feature is not to change the ore layer of lean ore and rich ore, only replace clay layer part.First, filling aggregate, sand, cement, car is transported to and stored in surface storage bin, and to the clay layer of ore pillar stepwise up hill excavation, filling material is prepared into uniform broken stone filling slurry after stirring, then it is transported to stope by concrete delivery pump, in the clay layer part being excavated Strip type broken stone concrete artificial ore pillar construction, this method is based on the traditional room and pillar mining method, replaces ore pillar clay layer part using artificial reinforcement layer to remold ore pillar mechanical environment, can effectively solve the problem that the strength of ore body clay layer is not enough, natural ore pillar cannot be retained, reach safe and efficient economic exploitation.

Description

Technical Field

[0001] This invention relates to the field of mining engineering technology, and specifically to a method for reshaping the mechanical environment of a pillar by replacing a clay layer. Background Technology

[0002] Room and pillar mining is a method where, under certain conditions, stops and pillars are alternately arranged within a ore block or mining area. Continuous or intermittent regular pillars are left during stop mining to protect the roof rock. It is suitable for mining stable horizontal or gently dipping ore bodies with a dip angle of less than 30°. It has advantages such as simple structure and mining process, minimal pre-mining and cutting work, high production capacity, good ventilation, and low mining costs, making it one of the most effective and widely used mining methods currently available.

[0003] However, as the mining depth increases, the mining environment becomes more complex. Low-strength geological environments such as clay layers often exist in the geological conditions, making it impossible to retain natural pillars, thus affecting the mining progress and safe and efficient production. Therefore, improving the mechanical properties of pillars plays a crucial role in ensuring the stability of the roof and overlying strata and the safe production of the mine. Summary of the Invention

[0004] This invention overcomes the adverse effects of the low strength of the geological environment and provides a method for reshaping the mechanical environment of a pillar by replacing the clay layer. By replacing the clay layer of the pillar, the mechanical environment of the pillar is reshaped, the strength of the pillar is improved, and the stability of the roof and overlying strata is ensured.

[0005] To achieve the above-mentioned technical objectives, the present invention provides a method for reshaping the mechanical environment of a mine pillar by replacing a clay layer, the specific steps of which are as follows:

[0006] S1. For a pillar containing a clay layer, the pillar includes a lean ore layer, a clay layer, and a rich ore layer. The stope is arranged using a room-and-pillar mining system. The ore blocks are divided along the strike or dip of the ore body. The rooms and pillars are arranged according to the ore blocks. The pillar is divided into several sections. The length of the room depends on the effective haulage distance of the transport equipment.

[0007] S2. Tunneling a transport roadway along the strike of the ore body, installing mining equipment and auxiliary equipment along the dip of the ore body, and tunneling and cutting the uphill and upper horizontal middle roadways to connect them to form a ventilation system, and transporting the mined ore away;

[0008] S3. The filling material is transported to the surface storage silo. The filling material includes aggregate, sand, and cement. A mobile concrete mixing plant is constructed underground. During the mining process of the stope, the pillar is reserved. The intermediate clay layer of the pillar is excavated in stages using mining equipment. At the same time, the filling material is quantitatively proportioned, mixed and prepared into a mixed solid, and then transported to the stope by a concrete pump. The excavated clay layer is then filled with strip-shaped artificial pillars. After the artificial reinforcement layer has solidified, the stope is mined in layers. The mining sequence is clay first, then rich ore, and finally lean ore.

[0009] S4. The excavated clay layer is transported to the adjacent unused mining area to form new support for the unused mining area. At the same time, after the artificial reinforcement layer solidifies, the mechanical environment of the pillar is reshaped, and the pillar is maintained continuously throughout the mining process.

[0010] Compared with the prior art, the technical solution of this application has the following beneficial technical effects:

[0011] 1. The room-and-pillar mining method, which reshapes the mechanical environment behavior of the clay layer in the ore body pillar, can effectively solve the problem of insufficient clay layer strength and inability to retain natural pillars during the mining process. It can improve the support of the pillars to the roof and overlying strata, and can also recover the pillars. This method ensures efficient and safe mining while having low economic cost and simple and fast operation.

[0012] 2. The excavated clay layer is transported to the adjacent undeveloped mining area by transport equipment, forming a stable new support for the undeveloped mining area. This not only saves on filling costs but also achieves zero-waste treatment of waste rock. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of the method for replacing the clay layer in a mine pillar provided by the present invention; Detailed Implementation

[0014] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0015] It should be noted that when an element is referred to as being "fixed to" another element, it can be directly attached to the other element or there may be an intervening element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or there may be an intervening element. The terms "vertical," "horizontal," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only possible implementation.

[0016] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0017] Please see Figure 1 This embodiment provides a method for reshaping the mechanical environment of a mine pillar by replacing a clay layer, comprising: a lean ore layer 1, a clay layer 2, a rich ore layer 3, and an artificial reinforcement layer 4, including the following steps:

[0018] S1. For a pillar containing a clay layer, the pillar includes a lean ore layer, a clay layer, and a rich ore layer. The stope is arranged using a room-and-pillar mining system. The ore blocks are divided along the strike or dip of the ore body. The rooms and pillars are arranged according to the ore blocks. The pillar is divided into several sections. The length of the room depends on the effective haulage distance of the transport equipment.

[0019] S2. Tunneling a transport roadway along the strike of the ore body, installing mining equipment and auxiliary equipment along the dip of the ore body, and tunneling and cutting the uphill and upper horizontal middle roadways to connect them to form a ventilation system, and transporting the mined ore away;

[0020] S3. The filling material is transported to the surface storage silo. The filling material includes aggregate, sand, and cement. A mobile concrete mixing plant is constructed underground. During the mining process of the stope, the pillar is reserved. The intermediate clay layer of the pillar is excavated in stages using mining equipment. At the same time, the filling material is quantitatively proportioned, mixed and prepared into a mixed solid, and then transported to the stope by a concrete pump. The excavated clay layer is then filled with strip-shaped artificial pillars. After the artificial reinforcement layer has solidified, the stope is mined in layers. The mining sequence is clay first, then rich ore, and finally lean ore.

[0021] S4. The excavated clay layer is transported to the adjacent unused mining area to form new support for the unused mining area. At the same time, after the artificial reinforcement layer solidifies, the mechanical environment of the pillar is reshaped, and the pillar is maintained continuously throughout the mining process.

[0022] The filling materials include aggregates, sand, and cement. It should be noted that the aggregates refer to coarse aggregates, including large-particle materials such as crushed stone and pebbles, while the sand refers to fine aggregates, including small-particle materials such as silt and river sand. A mobile concrete mixing plant is constructed underground. This mobile concrete mixing plant is moved along the direction in which the continuous pillar replaces the clay layer, filling the material as it is excavated. The reshaping of the pillar's mechanical environment refers to the alteration of the pillar's mechanical strength, ensuring it can adequately support the roof of the area. The mining sequence is clay first, then rich ore, and finally lean ore. This ensures sufficient extraction of rich ore, reduces the dilution rate of the phosphate rock by the clay layer, and allows for roof adjustments based on the actual roof conditions.

[0023] Preferably, the artificial reinforcement layer is formed after the filling material is mixed and stirred and rapidly injected into the excavated clay layer, and it forms a whole with the lean ore layer and the rich ore layer. When the artificial reinforcement layer 4 replaces the clay layer 2, it is injected and filled from the upper part of the hill downwards. The replacement process of the clay layer 2 is rapid. The auxiliary equipment quickly cleans out the clay layer and quickly fills the artificial reinforcement layer 4. The artificial reinforcement layer 4 needs to be prepared in advance. The artificial reinforcement layer 4 needs to be determined according to the site environment, including the strength of the crushed stone and the thin concrete mortar, as well as the bonding condition of the artificial reinforcement layer 4 with the upper and lower ore layers of the mine pillar.

[0024] Preferably, in the embodiment, the pillar is part of the ore body and is set up to ensure personnel safety and the stability of the mining area. The pillar can be composed of a lean ore layer 1, a clay layer 2, and a rich ore layer 3, or it can be composed of a rich ore layer 3, a clay layer 2, and a rich ore layer 3. The clay layer 2 has poor mechanical properties. It should be explained that the clay layer 2 can be a weak rock layer, that is, its own lithology is poor, and it is difficult to ensure the stability of the entire mining area. When the three parts of the pillar are a lean ore layer 1, a clay layer 2, and a rich ore layer 3, the clay layer is first treated. 2. Replacement is performed, and then, depending on the site conditions, the lean ore layer 1 is reinforced with roofing and anchor bolts. After the support is stable, the lean ore layer 1 is blasted, and then the lean ore layer 1 is mined. Finally, the ore is transported out using the transport equipment. After the upper lean ore layer 1 is mined, the rich ore layer 3 is mined by drilling and blasting until the mining is completed. When the pillar consists of rich ore layer 3, clay layer 2, and rich ore layer 3, or when the uppermost layer is a stable lean ore layer 1, the mining of the pillar can be carried out by direct drilling and blasting.

[0025] Preferably, the key point of replacing the clay layer 2 of the pillar is that the reshaping mechanical environment process only replaces the clay layer 2, and can mine the lean ore layer 1 and the rich ore layer 3. The thickness of the clay layer 2 is 2-3m, the bottom of the pillar adopts a flat bottom structure, and the tunneling machine is used to directly tunnel and transport the clay layer when it is tunneled uphill in steps.

[0026] Preferably, the tunneling machine can directly tunnel other continuous pillars during the uphill tunneling process. In other words, the pillars in the mining area can be interconnected, which facilitates the simultaneous mining of the lower rich ore layer and the transportation of materials.

[0027] Specifically, when mining the stope and the pillar, if the ore body thickness is less than 2.5m, the full thickness can be mined in one go; if the ore body thickness is between 2.5-3m, the full thickness can be mined in one go or in layers; if the ore body thickness is greater than 3m, it can be mined in layers.

[0028] Preferably, the mining equipment includes a tunneling machine and a loader, and the transport equipment includes an electric scraper. When using the electric scraper for transport, the length of the stope is generally 40-60m, the width of the stope is generally determined according to the thickness of the ore body and the stability of the roof, and is generally 8-20m, the diameter of the pillars is 3-7m, and the spacing is 5-8m.

[0029] Preferably, the pillar needs to be supported as needed. The artificial reinforcement layer 4 has a short curing period, generally 1-2 months. The pillar support includes roof support, bolt support, or bolt and shotcrete support.

[0030] In this embodiment, the stope layout is first determined by dividing the ore body into blocks along its strike or dip. Then, stopes and pillars are arranged within these blocks. Next, transport roadways are excavated along the ore body strike, with mining equipment rooms installed at intervals. The uphill and upper-level intermediate roadways are then excavated and connected to form a ventilation system and facilitate ore transport. Next, the stopes are mined using a room-and-pillar mining method, typically advancing from one side to the other or from the stopes to both sides along their strike. To improve mining efficiency, multiple stopes can be mined simultaneously. Finally, the mechanical environment of the stopes is reshaped, and pillars are recovered. Pillars are pre-reserved during the mining process. These pillars consist of a lean ore layer 1, a clay layer 2, and a rich ore layer 3. Mining equipment is used to excavate the intermediate clay layer 2 once, and the excavated clay layer is supported. Then, manual... Artificial reinforcement layer 4 fills the excavated clay layer. After artificial reinforcement layer 4 solidifies, the remaining clay layer 2 is backfilled by mining uphill and downhill. This process is repeated until the clay layer 2 and artificial reinforcement layer 4 are replaced. The excavated clay layer 3 is transported to the adjacent unmined area to form a new stable support for the unmined area. This saves filling costs and achieves zero-waste treatment of clay. At the same time, as artificial reinforcement layer 4 solidifies over time, the mechanical properties of the pillar change, forming a high-strength support. This avoids the problem of poor support caused by insufficient clay strength in the stope. The continuous pillar reshaped by the mechanical environment is preserved throughout the mining process. After artificial reinforcement layer 4 stabilizes, the rich ore layer 3 is blasted to extract ore. Finally, after the lower rich ore layer 3 is mined, the upper poor ore layer 3 is blasted to extract ore until the mining is completed.

[0031] The present invention will be further described in detail below with reference to specific embodiments.

[0032] A phosphate mine in Mabian County, Sichuan Province, has an ore body with a dip of approximately 7°. The ore body and surrounding rock have good stability, with an average thickness of 3.5m. The design adopts the room-and-pillar mining method, but the loss rate of the primary pillars has reached over 20%. The structural characteristics are layered and thin-layered, with weak structural planes sandwiched in between. The layered structure has a thickness of 3m, and further mechanical reshaping of the pillars is required to ensure normal mining in the mining area.

[0033] The specific steps are as follows:

[0034] S1. Divide the ore body into blocks along its strike or dip. The ore body has dimensions of 65m x 118m and is divided into two blocks. Each block has eight workings, with 4m x 4m pillars reserved at 8m intervals. The pillar dimensions and division are generally based on the average stress conditions, as shown in the following formula:

[0035]

[0036] In the formula, γ—rock mass unit weight; z—burial depth, m; w o w p— Width of the stope and pillar, in meters.

[0037] The phosphate mine has a stop span of 10m and a pillar spacing of 8m.

[0038] S2. Tunneling a transport roadway along the strike of the ore body, installing mining equipment tunneling machines and auxiliary equipment along the dip of the ore body, and tunneling and cutting the uphill and upper horizontal middle roadways to connect them to form a ventilation system, and transporting away the mined ore;

[0039] S3. Considering the strength of the artificial pillar after the artificial reinforcement layer replaces the clay layer, the calculation is performed according to the following formula:

[0040]

[0041] In the formula, S P — Pillar strength, MPa; S L —Rock mass strength parameters, MPa; w P Same as above, m; h—pillar height, m; α—constant, when when

[0042] Given that the aspect ratio of the pillar in this phosphate mine is less than 5, the strength of the pillar after replacement is calculated as follows:

[0043] S1=Fγz×(S γ / S K ) / [0.64+0.36(w P / h)]

[0044] In the formula, S1—compressive strength of the pillar after replacement, MPa; F—safety factor; S γ —Area of ​​the rock column, m 2 S K —Lower pillar area, m 2 .

[0045] Because the project's pillars are designed as continuous pillars, the compressive strength of the replaced continuous pillars is calculated to be 10.5 MPa according to the above formula. C20 concrete is selected on site. The filling materials are first transported to the surface storage silo. The filling materials include aggregates, sand, cement, fly ash, and additives. It should be explained that the additives here refer to materials that improve the performance of concrete. Preferably, the on-site mix ratio is cement:sand:crushed stone:fly ash = 7:16:24:1, and the amount of additives is 1% of the total amount. This can be adjusted according to the on-site construction conditions. A mobile concrete mixing plant is constructed underground. This plant moves along the direction of the pillar excavation. During the mining process, the pillar is reserved, and mining equipment is used to excavate the intermediate clay layer of the pillar in stages. Simultaneously, the filling material is mixed according to the aforementioned quantitative ratio to prepare a solidified mixture, which is then pumped to the pillar via a concrete pump. The excavated clay layer is then filled with artificial pillars in a strip-like manner. It should be noted that "strip-like" refers to the width of the tunneling machine; multiple routes for its back-and-forth movement constitute a strip-like structure. The loader quickly clears the clay layer while the concrete pump rapidly fills the artificial reinforcement layer. When replacing the clay layer, the artificial reinforcement layer is injected from the upper part of the incline downwards, using a step-by-step pouring method, with each pour being 1.5m long. Six pillars are poured simultaneously, with a daily pouring volume of 66m³. 3 The system employs a three-line pipeline connection, enabling rapid replacement of the clay layer. Because the ore body is inclined, the artificial reinforcement layer effectively bonds to the roof during top-down injection. After the filled artificial reinforcement layer solidifies, the stope is mined in layers. Depending on the site conditions, the solidification time is 28 days. After curing, the stope is mined in the following order: first clay, then rich ore, and finally lean ore. The tunneling machine passes through the continuous stope, forming a passage. When mining rich ore, the pillar bottom adopts a flat-bottom structure. When mining the upper lean ore, directional blasting technology is used to ensure the ore falls and accumulates in a predetermined direction.

[0046] S4. The excavated clay layer is transported to the adjacent unused mining area to form new support for the unused mining area. At the same time, after the artificial reinforcement layer solidifies, the mechanical environment of the pillar is reshaped, the strength of the replacement increases, and the pillar is maintained continuously throughout the mining process. The mechanical environment reshaping process only replaces the clay layer and does not change the ore layers of low-grade and high-grade ore.

[0047] According to the site conditions, the excavated clay layer needs to be supported. The bottom adopts a flat bottom structure. First, the bottom of the mine pillar is cut and anchor bolts are used for support. Triangular areas are set up and the anchor bolts are arranged according to the triangular areas. When the concrete is poured to the distance from the top plate, the top plate anchor bolts are installed. Then, the filling material is poured and cured after the pouring is completed.

[0048] This invention relates to a method for reshaping the mechanical environment of a mine pillar by replacing a clay layer. It effectively solves the problem that insufficient clay layer strength leads to unstable support for the stope during mining, resulting in the inability to retain natural pillars. By replacing the clay layer, the support of the pillar to the roof and overlying strata is improved, and the pillar can also be recovered. This ensures efficient and safe mining while maintaining low economic costs and a simple and quick operation method. Furthermore, the excavated clay layer can be transported to the adjacent unused mining area to form a stable new support for the unused area, saving filling costs and achieving zero-waste treatment of waste rock.

[0049] The specific embodiments of the present invention described above do not constitute a limitation on the scope of protection of the present invention. Any other corresponding changes and modifications made in accordance with the technical concept of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A method for reshaping the mechanical environment of a mine pillar by replacing a clay layer, characterized in that, Includes the following steps: S1. For a pillar containing a clay layer, the pillar includes a lean ore layer, a clay layer, and a rich ore layer. The stope is arranged using a room-and-pillar mining system. The ore blocks are divided along the strike or dip of the ore body. The rooms and pillars are arranged according to the ore blocks. The pillar is divided into several sections. The length of the room depends on the effective haulage distance of the transport equipment. S2. Tunneling a transport roadway along the strike of the ore body, installing mining equipment and auxiliary equipment along the dip of the ore body, and tunneling and cutting the uphill and upper horizontal middle roadways to connect them to form a ventilation system, and transporting the mined ore away; S3. The filling material is transported to the surface storage silo. The filling material includes aggregate, sand, and cement. A mobile concrete mixing plant is constructed underground. During the mining process of the stope, the pillar is reserved. The intermediate clay layer of the pillar is excavated in stages using mining equipment. At the same time, the filling material is quantitatively proportioned, mixed and prepared into a mixed solid, and then transported to the stope by a concrete pump. The excavated clay layer is then filled with strip-shaped artificial pillars. After the artificial reinforcement layer has solidified, the stope is mined in layers. The mining sequence is clay first, then rich ore, and finally lean ore. S4. The excavated clay layer is transported to the adjacent unused mining area to form new support for the unused mining area. At the same time, after the artificial reinforcement layer solidifies, the mechanical environment of the pillar is reshaped, and the pillar is maintained continuously throughout the mining process.

2. The method for reshaping the mechanical environment of a pillar by replacing the clay layer according to claim 1, characterized in that, The artificial reinforcement layer is formed by rapidly injecting the mixed and stirred filling material into the excavated clay layer, and it forms a whole with the poor ore layer and the rich ore layer. When the artificial reinforcement layer replaces the clay layer, it is injected and filled from the upper part of the mountain downwards.

3. The method for reshaping the mechanical environment of a pillar by replacing the clay layer according to claim 2, characterized in that: The strength of the artificial reinforcement layer is determined based on the site environment, including the strength of the crushed stone and the thin concrete mortar, as well as the bonding between the artificial reinforcement layer and the upper and lower ore layers of the mine pillar.

4. The method for reshaping the mechanical environment of a pillar by replacing the clay layer according to claim 1, characterized in that, The pillar is part of the ore body and is set up to ensure personnel safety and the stability of the mining area. The clay layer has poor mechanical properties and it is difficult to guarantee the stability of the entire mining area.

5. The method for reshaping the mechanical environment of a pillar by replacing the clay layer according to claim 1, characterized in that, The replacement process of the clay layer is rapid. The auxiliary equipment quickly removes the clay layer while simultaneously filling the artificial reinforcement layer, which needs to be prepared in advance.

6. The method for reshaping the mechanical environment of a pillar by replacing the clay layer according to claim 1, characterized in that, The reshaping mechanical environment process only replaces the clay layer and does not change the ore layers of poor and rich ore. The thickness of the clay layer is 2-3m, and the bottom of the ore pillar adopts a flat bottom structure.

7. The method for reshaping the mechanical environment of a pillar by replacing the clay layer according to claim 1, characterized in that, When mining the stope and pillars, if the ore body thickness is less than 2.5m, it can be mined in one go; if the ore body thickness is between 2.5-3m, it can be mined in one go or in layers; if the ore body thickness is greater than 3m, it can be mined in layers.

8. The method for reshaping the mechanical environment of a pillar by replacing the clay layer according to claim 1, characterized in that, The mining equipment includes a tunneling machine and a loader. The transport equipment includes an electric scraper. When using the electric scraper for transport, the length of the stope is generally 40-60m, the width of the stope is generally determined according to the thickness of the ore body and the stability of the roof, and is generally 8-20m. The diameter of the pillars is 3-7m, and the spacing is 5-8m.

9. The method for reshaping the mechanical environment of a pillar by replacing the clay layer according to claim 1, characterized in that, Depending on the circumstances, the excavated clay layer can be supported. The curing period for the artificial reinforcement layer is 1-2 months. The support for the mine pillar includes roof support, bolt support, or bolt and shotcrete support.

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