Method for recovering residual ore in a mined-out area

Abstract

The present disclosure relates to a method for recovering residual ore in a goaf, comprising the following steps: S1: cleaning and reinforcing a transport roadway at the bottom of the goaf, and vertically arranging a filling raise in an upper ore body of the goaf; S2: injecting water into the goaf through the filling raise to loosen and dissociate the cemented residual ore in the goaf, and allowing the cemented residual ore to fall and collect to a lower mining working face under the action of its own gravity; S3: injecting filling material into the upper part of the goaf through the filling raise to form a filling body; S4: taking the transport roadway as a working basis, layer-by-layer mining the bottom residual ore from bottom to top, after the construction of each mining layer is completed, filling the layer space with filling material; and S5: after the bottom residual ore is recovered, layer-by-layer mining the top residual ore from the top of the goaf using a downward drift, after the construction of each mining layer is completed, simultaneously filling the layer space with filling material, until the residual ore in the goaf is completely recovered. In this way, the recovery rate of residual ore in an old goaf is effectively improved.

Description

Technical Field

[0001] This disclosure relates to the field of underground mining technology, and more specifically, to a method for recovering residual ore from mined-out areas. Background Technology

[0002] During underground mining of metal mines, due to limitations in early mining techniques and technology, some mines have left behind a large number of pillars and residual ore after using methods such as shallow-hole ore retention. These goaf areas were formed early, have complex spatial structures, are generally fractured, and have relatively poor surrounding rock stability, which brings great difficulties to subsequent residual ore recovery and safe production.

[0003] For goaf areas formed by the ore retention method, during the mining process, the mining operation is often difficult to continue upward due to factors such as increased ground pressure manifestation, limited ventilation and transportation conditions, thus forcing the retention of the roof pillar for a long period of time. At the same time, some ore gradually becomes compacted, arched or suspended due to long-term stress, moisture migration and cementation of fine-grained minerals during the retention period, making it difficult for the ore to be released naturally.

[0004] For the aforementioned pillars and residual ore in the goaf, existing recovery methods mostly employ secondary blasting and forced ore release. However, under conditions of fractured ore and rock and high ore compaction, blasting operations often only create loosened areas locally, making it difficult to achieve overall loosening and ore release, and easily inducing instability in the upper loose mass, posing a threat to the safety of the bottom roadways and workers. In addition, for old goaf areas with complex spatial structures and a large amount of loose and compacted ore bodies, conventional backfilling mining methods also have certain limitations in terms of spatial management and coordinated mining. Summary of the Invention

[0005] The purpose of this disclosure is to provide a method for recovering residual ore from goaf areas, so as to at least partially solve the problems existing in related technologies.

[0006] To achieve the above objectives, this disclosure provides a method for recovering residual ore from goaf areas, comprising the following steps: S1: Clean and reinforce the transport roadways at the bottom of the goaf, and vertically arrange filling risers in the upper ore body of the goaf; S2: Water is injected into the goaf through the filling well to loosen and disintegrate the hardened residual ore in the goaf, which falls and collects to the lower mining face under its own gravity. S3: Filling material is injected into the upper part of the goaf through the filling well, and solidified to form a filling body; S4: Using the transport roadway as the working foundation, the bottom residual ore is mined layer by layer from bottom to top. After each layer of mining is completed, the void in that layer is filled with backfill material; and S5: After the bottom residual ore is recovered, the top residual ore is mined layer by layer at the top of the goaf using a downward approach. After each mining layer is completed, backfilling is carried out simultaneously, and backfilling material is used to fill the goaf of that layer until all residual ore in the goaf is recovered.

[0007] In some possible implementations, step S1 further includes: vertically arranging pedestrian ventilation shafts on both sides of the goaf, arranging ore chute shafts on the side of the pedestrian ventilation shafts closer to the goaf, and separating the pedestrian ventilation shafts and the ore chute shafts by a partition plate.

[0008] In some possible implementations, the ore chute is located close to the goaf, and an external transport roadway connected to the bottom of the ore chute is excavated as the ore outlet.

[0009] In some possible implementations, in step S4, water is injected into the interior of each layer before the bottom residual ore is mined to loosen and disintegrate the hardened residual ore.

[0010] In some possible implementations, in step S4, a false tunnel approach is used to mine the bottom residual ore in layers. Each layer is constructed by advancing in sections within that layer. After each section of the approach is excavated, the section is filled. The process is continued section by section until the mining of that layer is completed, and then the remaining layers are constructed in sequence.

[0011] In some possible implementations, when mining the bottom residual ore, a false tunnel-like approach is constructed using an advanced support structure. Before the approach is excavated, the advanced support structure is laid in front of the mining face, and its front end extends into the interior of the ore body above.

[0012] In some possible implementations, the advanced support structure includes advanced drill rods, support beams, and locking beam bolts, wherein the support beams are vertically installed on the bottom plate of the working face, the advanced drill rods are supported above the support beams and extend forward into the upper ore body, and the locking beam bolts are used to fix adjacent support beams.

[0013] In some possible implementations, in step S5, when mining the top residual ore, the process proceeds synchronously from both sides of the ore body towards the center, and the ore is recovered layer by layer by electric scraper. The ore is then collected and transported through the ore pass.

[0014] In some possible implementations, during step S5, when mining the top residual ore using a downward approach, an artificial false bottom structure is constructed below each layer of ore body after mining it.

[0015] In some possible implementations, after both the bottom and top residual ore have been mined out, the entire goaf is filled with a mixture of waste rock and concrete through the filling well, and then compacted and consolidated.

[0016] Through the above technical solution, by reinforcing the roadways in the goaf in the early stage, setting up special filling wells, coordinating with hydraulic injection to loosen the compacted residual ore, pre-constructing solidified filling bodies in the upper part, and combining the bottom residual ore with layered mining and filling from bottom to top, and the top residual ore with layered mining and filling from the downward approach, the entire residual ore recovery operation is kept in a stable state. This effectively prevents the instability and collapse of the compacted ore body and the suspended surrounding rock, avoiding safety impacts on the lower transport roadways and workers. It solves the problems of difficult residual ore recovery, high safety risks, and incomplete ore body recovery in traditional goaf areas. Under the premise of ensuring the safety of underground operations, it significantly improves the recovery rate of residual ore at the bottom and top of the goaf, is safe and reliable, and can completely eliminate the risk of goaf collapse.

[0017] Other features and advantages of this disclosure will be described in detail in the following detailed description section. Attached Figure Description

[0018] The accompanying drawings are provided to further illustrate the present disclosure and form part of the specification. They are used together with the following detailed description to explain the present disclosure, but do not constitute a limitation thereof. In the drawings: Figure 1 This is a flowchart illustrating an exemplary method for recovering residual ore in a goaf according to this disclosure; Figure 2 This is a schematic diagram of a goaf area for a method of recovering residual ore from a goaf area, as exemplarily illustrated in this disclosure. Figure 1 ; Figure 3 yes Figure 2 Cross-sectional view along the AA direction; Figure 4 yes Figure 2 Cross-sectional view along the BB direction; Figure 5 This is a schematic diagram of a goaf area for a method of recovering residual ore from a goaf area, as exemplarily illustrated in this disclosure. Figure 2 ; Figure 6 This is a schematic diagram of a goaf area for a method of recovering residual ore from a goaf area, as exemplarily illustrated in this disclosure. Figure 3 ; Figure 7 This is a schematic diagram of a goaf area for a method of recovering residual ore from a goaf area, as exemplarily illustrated in this disclosure. Figure 4 ; Figure 8 This is a schematic diagram of an advanced support structure exemplarily shown according to this disclosure; Figure 9 This is a side view of an advanced support structure exemplarily shown according to this disclosure; Figure 10 This is a top view of an advanced support structure exemplarily shown according to this disclosure.

[0019] Explanation of reference numerals in the attached figures 1-Transport roadway; 2-Backfilling shaft; 3-Ore; 30-Crusted residual ore; 31-Bottom residual ore; 32-Top residual ore; 41-Personnel ventilation shaft; 42-Ore chute shaft; 5-External transport roadway; 6-Advanced support structure; 61-Advanced drill rod; 62-Support beam; 63-Locking beam bolt; 7-Backfill body; 8-Electric scraper chamber; 9-Electric scraper. Detailed Implementation

[0020] The specific embodiments of this disclosure will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit this disclosure.

[0021] In this disclosure, unless otherwise stated, the directional terms "upper" and "lower" should be understood based on the application environment of the relevant components. "Inner" and "outer" refer to the outline of the corresponding parts themselves. In this disclosure, when the following description refers to the accompanying drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements.

[0022] Reference Figure 1 This disclosure provides a method for recovering residual ore in a goaf, which may include the following steps: S1: First, thoroughly clean the transport roadway 1 at the bottom of the goaf, remove scattered gravel and debris, check the stability of the surrounding rock, and reinforce damaged or loose parts to ensure the stability and safety of the working passage. Then, vertically excavate and construct a filling riser 2 inside the ore body above the goaf. The filling riser 2 is vertically connected and serves as a dedicated passage for subsequent water injection and transportation of filling material; S2: Refer to... Figure 5Through the filling well 2 completed in the previous stage, water is injected uniformly into the goaf. The water flow soaks the hardened residual ore 30 in the goaf, breaking up the hardened state of the ore body and fully loosening and disintegrating the compacted ore body. The disintegrated ore 3 loses its consolidation force and falls naturally under its own gravity, converging at the mining face below the goaf to facilitate subsequent mining operations. It is important to control the water flow rate during the water injection process to avoid eroding the surrounding rock and causing collapse. S3: Continue to inject prepared filling material into the upper space of the goaf through the filling well 2. The filling material can be waste rock and foamed concrete. As a lightweight filling material, foamed concrete can fill the voids and combine with the surrounding ore and rock through good fluidity to form an integral and stable filling structure. This filling structure can provide support during subsequent mining, reduce the risk of ore body instability, and provide stable support for subsequent mining operations. After the backfill material is poured, it is left to cure until it is completely solidified, forming a stable upper backfill body. This body supports the surrounding rock at the top of the goaf, isolates the loose ore body above, and creates a safe working environment for subsequent mining of the remaining ore at the top, preventing the surrounding rock from falling off or collapsing. S4: Refer to... Figure 6 Using the reinforced transport roadway 1 as the working foundation, the bottom residual ore 31 of the goaf is mined. A bottom-up, layered mining method is adopted, dividing the bottom ore body into multiple mining layers, and constructing each layer one by one. The bottom residual ore 31 may include bottom pillars and slab ore bodies. After each layer of mining is completed, backfill material (foamed concrete) is immediately used to densely fill the goaf formed after the layer of mining, and after solidification, a support structure is formed before the next layer of mining is carried out, ensuring the safety of the mining process and avoiding safety hazards caused by exposed goaf; and S5: refer to Figure 7 After all the bottom residual ore 31 has been recovered, the process is moved to the top of the goaf and the top residual ore 32 is mined layer by layer using a downward approach. The top residual ore 32 may include the pit ore and the pillar ore body. After each mining layer is completed, backfilling operations are carried out simultaneously. Backfill material (foamed concrete) is used to fill the goaf layer densely. Construction is advanced layer by layer until all residual ore in the goaf is recovered. Throughout the process, one layer is mined and one layer is backfilled, and strict safety controls are implemented to ensure that no exposed goaf areas are left.

[0023] Through the above technical solution, by reinforcing the roadways in the goaf in the early stage, setting up special filling wells, coordinating with hydraulic injection to loosen the compacted residual ore, pre-constructing solidified filling bodies in the upper part, and combining the bottom residual ore with layered mining and filling from bottom to top, and the top residual ore with layered mining and filling from the downward approach, the entire residual ore recovery operation is kept in a stable state. This effectively prevents the instability and collapse of the compacted ore body and the suspended surrounding rock, avoiding safety impacts on the lower transport roadways and workers. It solves the problems of difficult residual ore recovery, high safety risks, and incomplete ore body recovery in traditional goaf areas. Under the premise of ensuring the safety of underground operations, it significantly improves the recovery rate of residual ore at the bottom and top of the goaf, is safe and reliable, and can completely eliminate the risk of goaf collapse.

[0024] Among them, reference Figure 2 Step S1 may further include: vertically arranging pedestrian ventilation shafts 41 on both sides of the goaf, and arranging ore chute shafts 42 on the side of the pedestrian ventilation shafts 41 closest to the goaf, with the pedestrian ventilation shafts 41 and ore chute shafts 42 separated by a partition plate. Step S1 may further include: vertically excavating and constructing pedestrian ventilation shafts 41 on both sides of the goaf, with the pedestrian ventilation shafts 41 running vertically to meet the needs of underground workers for passage, ventilation in the mining area, and pipeline laying. On the side of each pedestrian ventilation shaft 41 closest to the goaf, a separate ore chute shaft 42 is constructed, also using a vertical excavation method, specifically for the lowering and collection of ore 3, achieving separation of ore extraction operations from personnel passage and ventilation channels. A sturdy partition is used to separate the pedestrian ventilation shaft 41 from the ore chute shaft 42 to prevent ore 3 from rolling into the ventilation and pedestrian passage, thus preventing blockage of the passage, damage to facilities, and threats to the safety of workers, and ensuring that various operations do not interfere with each other and can be carried out in an orderly manner.

[0025] Furthermore, referring to Figure 3 , Figure 4 The ore pass 42 is installed close to the inner wall of the goaf, shortening the transfer distance of ore 3 and reducing the loss of ore 3 during transfer. It also avoids increased roadway construction costs caused by long-distance installation. At the bottom of the ore pass 42, an external transport roadway 5 is excavated and connected to the bottom of the ore pass 42. This external transport roadway 5 serves as a dedicated ore extraction channel. Ore 3 lowered through the ore pass 42 falls directly into the external transport roadway 5, facilitating subsequent centralized transfer and transportation. This achieves seamless connection between ore extraction and transfer processes, improving ore extraction efficiency without interfering with the internal mining operations in the goaf, ensuring orderly underground construction.

[0026] As an exemplary embodiment of this disclosure, during the construction process of mining the bottom residual ore 31 in step S4, before carrying out mining operations for each layer of bottom residual ore 31, clean water is injected into the interior of the layer to be mined in advance. The water is used to wet and disturb the ore body, so that the solidified and compacted residual ore 30 inside the layer is fully loosened and disintegrated, reducing the hardness of the ore body and the difficulty of mining, avoiding disturbance to the surrounding rock caused by forced crushing and excavation, while reducing the residue of ore 3, improving the recovery efficiency of bottom residual ore, and ensuring the smooth progress of mining operations.

[0027] Furthermore, referring to Figure 6 In step S4, a false tunnel approach is used to mine the bottom residual ore 31 in layers. During construction, each mining layer is divided into multiple small sections. Within each layer, excavation is carried out segment by segment along the advancing direction, proceeding forward section by section. After each section of the tunnel is completed, the void formed by that section is immediately filled with backfill material. Once the backfill material has solidified and reached the required strength, the next section is advanced, and this process is repeated segment by segment until the entire layer is mined. After a single layer is completed, the remaining layers above are mined sequentially using the same process, achieving simultaneous mining and backfilling, strictly controlling the exposed void area, and ensuring the safety of the mining operation.

[0028] In some embodiments, refer to Figure 6 When mining the bottom residual ore (31), an advanced support structure 6 is used to construct a false tunnel-type access road to provide safety protection for underground operations. Before the formal excavation of the access road, the advanced support structure 6 is deployed in advance in front of the mining face, and the front end of the advanced support structure 6 is extended into the upper ore body to achieve advanced support, stabilize the surrounding rock in advance, isolate the loose upper ore body, prevent the ore body from falling off and collapsing during the excavation process, completely eliminate the hidden danger of falling rocks at the top of the working face, ensure the safety of the false tunnel-type access road construction, and provide a stable working space for subsequent segmented mining and segmented filling operations.

[0029] Specifically, refer to Figures 8 to 10 The advanced support structure 6 may include advanced drill rods 61, support beams 62, and locking bolts 63. During construction, the support beams 62 are vertically fixed to the bottom plate of the longwall face to ensure the stability of the support and provide vertical support. The advanced drill rods 61 are erected on top of the support beams 62, supported by the support beams 62, and extend towards the interior of the ore body, with the front end extending forward into the upper ore body to achieve advanced roof protection. Specifically, the advanced drill rods 61 are arranged along a diagonal forward direction. Adjacent support beams 62 are fastened together by locking bolts 63 to form an integral support frame, improving structural stability and compressive strength, preventing support displacement and disintegration, and further ensuring the safety of working face operations.

[0030] In some embodiments, refer to Figure 7In step S5, during the mining of the top residual ore 32, a symmetrical mining method is adopted, with operations proceeding synchronously from both sides of the ore body towards the center. This ensures uniform stress distribution within the ore body and avoids localized stress concentration that could lead to rock instability. During the mining process, an electric scraper 9 is used for ore extraction, crushing and recovering ore 3 layer by layer. The recovered ore 3 falls under its own weight and is collected through the ore pass 42 located close to the goaf. It is then transported to the outside via the external transport roadway 5 below, achieving a seamless mining, ore extraction, and transport process, improving construction efficiency, and ensuring operational safety.

[0031] Furthermore, referring to Figure 7 In step S5, during the entire process of mining the top residual ore 32 using the downward approach, the first layer of artificial false bottom must be constructed before subsequent layered mining operations can be carried out. The entire process follows the construction technology of layered mining and layered support. Before starting the downward approach mining, the first layer of artificial false bottom is constructed at the top of the goaf and below the upper stable ore body to protect the upper roadway and surrounding rock, prevent the upper roadway from collapsing and being damaged, and safeguard the safe working face at the top. After each layer of ore body mining is completed, an artificial false bottom structure is immediately constructed at the lower position of that mining layer. The artificial false bottom is dense and solid, serving as a load-bearing support and isolating the upper and lower layers. It can provide a flat and stable working platform for the next layer of mining operations, and also prevent the upper broken ore and surrounding rock from falling, eliminating safety hazards and ensuring the orderly and safe conduct of the downward approach layered mining operations.

[0032] According to some embodiments, after all the residual ore at the bottom 31 and top 32 of the goaf have been mined out, the entire goaf is then sealed and filled. Through the previously installed filling wells 2, a mixture of waste rock and concrete is pumped into the goaf to fully fill it. During the filling process, the filling material is spread, compacted, and consolidated layer by layer to ensure that the filling is dense, uniform, and meets strength standards. This completely eliminates the risk of collapse and falling in the goaf, stabilizes the surrounding rock, restores the geological stability of the mining area, and prevents subsequent safety risks.

[0033] To accommodate the entire mining operation of bottom residual ore 31 and top residual ore 32, electric scrapers 9 and dedicated electric scraper chambers 8 are deployed in the corresponding working areas to achieve segmented mining and efficient transfer. For the mining of bottom residual ore 31, electric scraper chambers 8 are excavated in stable rock near transport roadway 1 and ore pass 42. Electric scrapers 9 are placed inside electric scraper chambers 8, and loose ore is scraped layer by layer using electric scrapers 9, collecting ore 3 to ore pass 42, and then transported out through external transport roadway 5. Electric scraper chambers 8 are reinforced and supported to protect equipment from falling rocks and ensure smooth mining. For the mining of top residual ore 32, an upper electric scraper chamber 8 is specially constructed in the stable surrounding rock above the goaf and near ore pass 42. Electric scrapers 9 are fixedly installed inside electric scraper chamber 8, with the scraping range covering the entire working face. During mining, the process proceeds synchronously from both sides of the ore body towards the center. Electric scrapers 9 are used to scrape and transport the ore 3 layer by layer, and then send it to the ore pass 42 for collection and transfer. The electric scraper chamber 8 isolates loose and dangerous rocks, protects equipment and personnel safety, and avoids interfering with normal mining operations.

[0034] The preferred embodiments of the present disclosure have been described in detail above with reference to the accompanying drawings. However, the present disclosure is not limited to the specific details of the above embodiments. Within the scope of the technical concept of the present disclosure, various simple modifications can be made to the technical solutions of the present disclosure, and these simple modifications all fall within the protection scope of the present disclosure.

[0035] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, this disclosure will not describe the various possible combinations separately.

[0036] Furthermore, various different embodiments of this disclosure can be combined in any way, as long as they do not violate the spirit of this disclosure, they should also be regarded as the content disclosed in this disclosure.

Claims

1. A method for recovering residual ore from a goaf, characterized in that, Includes the following steps: S1: Clean and reinforce the transport roadways at the bottom of the goaf, and vertically arrange filling risers in the upper ore body of the goaf; S2: Water is injected into the goaf through the filling well to loosen and disintegrate the hardened residual ore in the goaf, which falls and collects to the lower mining face under its own gravity. S3: Filling material is injected into the upper part of the goaf through the filling well, and solidified to form a filling body; S4: Using the transport roadway as the working foundation, the bottom residual ore is mined layer by layer from bottom to top. After each layer of mining is completed, the void in that layer is filled with backfill material; and S5: After the bottom residual ore is recovered, the top residual ore is mined layer by layer at the top of the goaf using a downward approach. After each mining layer is completed, backfilling is carried out simultaneously, and backfilling material is used to fill the goaf of that layer until all residual ore in the goaf is recovered.

2. The method for recovering residual ore in a goaf according to claim 1, characterized in that, Step S1 further includes: vertically arranging pedestrian ventilation shafts on both sides of the goaf, arranging ore chute shafts on the side of the pedestrian ventilation shafts closer to the goaf, and separating the pedestrian ventilation shafts and the ore chute shafts with a partition plate.

3. The method for recovering residual ore in a goaf according to claim 2, characterized in that, The ore chute is located close to the goaf, and an external transport roadway connected to the bottom of the ore chute is excavated as the ore outlet.

4. The method for recovering residual ore in a goaf according to claim 1, characterized in that, In step S4, before mining the bottom residual ore of each layer, water is injected into the interior of that layer to loosen and disintegrate the hardened residual ore.

5. The method for recovering residual ore in a goaf according to claim 1, characterized in that, In step S4, a false tunnel approach is used to mine the bottom residual ore in layers. Each layer is advanced in sections within that layer. After each section of the approach is excavated, the section is filled. The process is continued section by section until the mining of that layer is completed. Then, the remaining layers are constructed in sequence.

6. The method for recovering residual ore in a goaf according to claim 5, characterized in that, When mining the bottom residual ore, a false tunnel-type access road is constructed using an advanced support structure. Before the access road is excavated, the advanced support structure is laid in front of the mining face, and its front end extends into the interior of the ore body above.

7. The method for recovering residual ore in a goaf according to claim 6, characterized in that, The advanced support structure includes advanced drill rods, support beams, and locking beam bolts. The support beams are vertically installed on the bottom plate of the working face. The advanced drill rods are supported above the support beams and extend forward into the upper ore body. The locking beam bolts are used to fix adjacent support beams.

8. The method for recovering residual ore in a goaf according to claim 2, characterized in that, In step S5, when mining the top residual ore, the process proceeds synchronously from both sides of the ore body towards the center, and the ore is recovered layer by layer by electric scraper. The ore is then collected and transported through the ore pass.

9. The method for recovering residual ore in a goaf according to claim 1, characterized in that, In step S5, during the process of mining the top residual ore using a downward approach, an artificial false bottom structure is constructed below each layer of ore body after mining each layer.

10. The method for recovering residual ore in a goaf according to claim 2, characterized in that, After the bottom and top residual ore have been completely mined, the entire goaf is filled with a mixture of waste rock and concrete through the filling well, and then compacted and consolidated.

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