Return air waste heat circulation consolidation system for coal slime-based filling material

Abstract

The invention belongs to the field of coal mine cemented filling mining, and particularly discloses a return air waste heat circulating consolidation system for a coal slime-based filling material, which is characterized in that a heat exchange pipeline is pre-buried in a filling body between coal pillars, mine return air waste heat is utilized to accelerate dehydration consolidation of the coal slime-based filling material, and seepage water is recovered to realize secondary utilization. The system comprises an air inducing device, a heat preservation pipeline, a gas flow dividing device, a heat exchange pipeline and a water storage device. The air inducing device is arranged at the air return well bottom; the upper part of the heat exchange pipeline is arranged in the water permeable tank and is used for accelerating dehydration and solidification of the coal slime-based filling material and collecting exuded water; the heat exchange pipelines are all connected to the same gas distribution device which is connected with an air inducing device through a heat preservation pipeline. The tail end of the heat exchange pipeline is connected with a water storage device. The method has the characteristics of economy, energy conservation, environmental protection and high dehydration efficiency, the compactness and the early strength of the filling body are remarkably improved, and the energy consumption and the environmental influence of filling mining are reduced.

Description

Technical Field

[0001] The invention relates to the field of coal mine cementing filling mining, and in particular to a return air waste heat circulation consolidation system for coal slime-based filling materials. Background Art

[0002] During coal mining, the heat of the working face mainly comes from the heat dissipated by the coal wall, human body and mechanical equipment, as well as the heat brought by the gas gushing out of the coal body. This heat is exchanged with the air at the bottom of the well, which increases the temperature of the return air flow, thereby taking away most of the heat from the working face. After leaving the working face, affected by the ground temperature of the coal mine, the return air flow loses less heat and the temperature is basically constant. According to statistics, the temperature of most return air flows in winter remains above 15°C, which is stable and high-quality, and has a high utilization value.

[0003] Room-and-pillar mining is a common method in my country's coal mining. However, if the coal pillars are not recovered, this method will lead to a large amount of high-quality coal resources being wasted and problems such as spontaneous combustion of the remaining coal will occur. If the coal pillars are directly recovered, the stable structure between the coal pillars and the roof and floor plates may be destroyed. Therefore, how to safely and efficiently recover the coal pillars has become a key issue restricting the development of coal mines.

[0004] Limited by the size of coal pillars and surrounding rock stress, the traditional coal pillar recovery methods mainly include bag-wing type, external entry type and split-pillar type, but these methods have the disadvantages of low recovery rate and significant safety risks. To solve this problem, a method of using coal slime-based filling materials to fill the coal room goaf and then recovering the entire area after solidification has emerged. This method can realize the recovery of all coal pillars and reduce the possibility of mine pressure and spontaneous combustion. However, coal slime-based filling materials have the disadvantages of low dehydration efficiency and long cycle, and incomplete dehydration of the filling body will cause structural defects. Therefore, accelerating the dehydration and consolidation of coal slime-based filling materials is the focus of current research.

[0005] Traditional dehydration and consolidation methods for coal slime-based filling materials mainly rely on natural drying or external heating, but these methods have problems such as low efficiency and high energy consumption. Summary of the invention

[0006] The purpose of the present invention is to provide a return air waste heat circulation consolidation system for coal slime-based filling materials, so as to solve the above-mentioned technical problems existing in the prior art.

[0007] To achieve the above-mentioned purpose, the present invention provides the following scheme: a return air waste heat circulation consolidation system for coal slime-based filling materials, comprising a plurality of heat exchange pipes pre-buried in the filling body between coal pillars, the upper part of the heat exchange pipes being arranged in a water-permeable trough, for accelerating the dehydration and consolidation of the coal slime-based filling materials and collecting the seeping moisture; the heat exchange pipes are all connected to the same gas diversion device, the gas diversion device is connected to the induced draft device through an insulating pipe, the induced draft device is arranged at the bottom of the return air shaft, for introducing mine return air containing waste heat; the end of the heat exchange pipe is connected to a water storage device, for storing the recovered moisture and realizing secondary utilization.

[0008] The above structure aims to propose an economical, energy-saving, green and environmentally friendly return air waste heat circulation consolidation system with high dehydration efficiency. An induced draft device is arranged at the bottom of the return air shaft to recycle the waste heat of the mine return air. The heat source is stable, avoiding the waste of resources caused by directly discharging the return air into the atmosphere. Heat exchange pipes made of heat-conducting materials are arranged in the filling body to increase the heat exchange contact area. The heat can effectively accelerate the dehydration and consolidation speed of the coal slime-based filling material and improve the production efficiency of the filling and mining operation.

[0009] In some optional solutions of the present invention, at least one relay fan is arranged at a preset distance along the length direction of the insulation pipe.

[0010] In some optional solutions of the present invention, the air inducing device includes:

[0011] The filter screen is detachably mounted at the air inlet of the air induction device to intercept solid particles in the air flow;

[0012] The high-pressure spray gun is detachably connected to the inner side of the air inlet of the air inducing device and is used for cleaning the filter screen.

[0013] The air induced device in the present invention can filter impurities such as coal dust and rock dust in the airflow through a filter net, and is equipped with a high-pressure spray gun. When the amount of impurities accumulated is too much, gas or liquid can be sprayed during non-working hours to regularly clean the blocked filter net, and the filter net can be disassembled and replaced when it reaches its service life.

[0014] In some optional solutions of the present invention, the gas flow distribution device has an annular pressure balance chamber, and one end of each of the heat exchange pipes is connected to the annular pressure balance chamber.

[0015] In some optional solutions of the present invention, a porous plate is provided at the connection position between the annular pressure balance chamber and the heat exchange pipe, and a plurality of through holes are provided on the porous plate for regulating the flow rate and distribution of the wind flow.

[0016] In some optional solutions of the present invention, one side of each of the porous plates is connected to a regulating valve, and the regulating valve is used to control the number of passages in the porous plate to achieve airflow distribution to different heat exchange pipes.

[0017] The gas diversion device of the present invention is designed as an annular pressure balance chamber, which can reduce the wind speed by expanding the flow area, and install a porous plate in front of the diversion pipe to reduce the wind pressure and flow velocity in the heat exchange pipe, avoiding excessive wind pressure and excessive flow velocity that lead to reduced heat exchange efficiency and water seepage effect between the hot air flow and the filling body, while realizing quantitative control of the air flow rate, improving the applicability and flexibility of the system.

[0018] In some optional solutions of the present invention, the heat exchange pipe is arranged obliquely in the middle and lower part of the filling body of the goaf, and the inclination angle is 2 to 5 degrees.

[0019] In some optional solutions of the present invention, the outer diameter of the heat exchange pipe is 1 / 8 to 1 / 10 of the height of the goaf.

[0020] In some optional schemes of the present invention, a water-permeable groove is opened on the upper part of the heat exchange pipe, and the water-permeable groove extends along the length direction of the heat exchange pipe. A layer of geotextile is installed in the middle of the water-permeable groove, and a layer of wire mesh is installed above and below the geotextile.

[0021] The present invention provides a water-permeable groove on the upper part of the heat exchange pipe, which allows excess water seeping from the filling material to enter the pipe and be discharged into the water storage device, thereby realizing the secondary utilization of mine water; the water-permeable groove adopts the alternating arrangement of water-permeable slurry insulation material geotextile and wire mesh, which effectively prevents large particles of solid from entering the heat exchange pipe and causing pipe blockage while ensuring that the pipe is not crushed.

[0022] In some optional solutions of the present invention, the mesh size of the wire mesh satisfies the formula:

[0023] d net ≤k×d interception ;

[0024] Among them, d net is the mesh size of the wire mesh, k is the safety margin factor, which is 0.7 to 0.9, d interception It is the equivalent particle size of D30 particles in coal slime-based filling materials.

[0025] In some optional schemes of the present invention, the end of the heat exchange pipe is connected to a water storage device, which is used to store water seeping from the filling body. A liquid level sensor and a drain valve are installed inside the water storage device, and an exhaust port that can filter the airflow is arranged above the liquid level sensor.

[0026] Furthermore, the drain outlet is arranged at a height of 1 / 4 upward from the bottom of the water storage device, which can reduce the discharge of bottom sediments. The bottom plate of the water storage device is detachable, and the sediments can be cleaned separately during non-working hours.

[0027] The present invention also arranges a water storage device at the end of the heat exchange pipe, which can be used to store water seeping out of the filling body and filter the wind flow. When the liquid reserve is excessive or after static sedimentation, the drain valve can be opened to discharge the water through the drain port. After further water purification, it can be used for secondary utilization such as water for filling materials, cooling of mining equipment and spray dust removal.

[0028] Compared with the prior art, the present invention at least discloses the following beneficial effects:

[0029] The present invention proposes a return air waste heat circulation consolidation system for coal slime-based filling materials, which has significant economic, environmental and efficiency improvement effects. By recycling the waste heat of mine return air, energy waste is avoided, the external heating energy consumption required by the traditional dehydration consolidation method is reduced, and the operating cost of filling and mining is significantly reduced. At the same time, the system uses the waste heat of mine return air to accelerate the dehydration and consolidation speed of coal slime-based filling materials, shorten the consolidation cycle, and improve the production efficiency of filling and mining operations. In addition, the system reduces the waste of mine water by recycling the water seeping out of the filling body and realizing secondary utilization, which is environmentally friendly. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0031] Figure 1 This is a schematic diagram of the overall structure of the return air waste heat circulation consolidation system for coal slime-based filling materials proposed by the present invention;

[0032] Figure 2 This is a front view of the air induction device in the system of the present invention;

[0033] Figure 3 It is a side internal structure diagram of the air induction device in the system of the present invention;

[0034] Figure 4 It is a structural diagram of the air inlet of the air induction device in the system of the present invention;

[0035] Figure 5 It is a structural diagram of the outlet of the induced draft device in the system of the present invention;

[0036] Figure 6 It is a schematic diagram of the structure of the gas flow splitting device in the system of the present invention;

[0037] Figure 7 for Figure 6 Sectional view at AA in the middle;

[0038] Figure 8 It is a schematic diagram of the structure of the heat exchange pipeline unit in the system of the present invention;

[0039] Fig. 9 for Figure 8 Sectional view at the middle BB;

[0040] Fig.10 for Fig. 9 A partial enlarged view of point C in the middle;

[0041] Fig.11 It is a schematic diagram of the structure of the water storage device in the system of the present invention;

[0042] Fig.12 The figure is a schematic diagram of the arrangement position of the heat exchange pipes in the system of the present invention.

[0043] In the figure: 1. induced draft device; 11. filter screen; 12. high-pressure spray gun; 2. insulation pipe; 3. gas diversion device; 31. annular pressure balance chamber; 32. porous plate; 33. regulating valve; 4. relay fan; 5. heat exchange pipe; 51. water-permeable trough; 52. water-permeable hole; 53. geotextile; 54. wire mesh; 6. water storage device; 61. liquid level sensor; 62. drain valve; 63. exhaust port; 7. return air shaft. DETAILED DESCRIPTION

[0044] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0045] Based on the limitations of existing mine return air waste heat utilization technology and the problems existing in the application of coal slime-based filling materials, the present invention proposes a return air waste heat circulation consolidation system for coal slime-based filling materials, which is mainly used for the consolidation of coal slime-based filling materials in room-and-pillar mining. By pre-arranging pipelines in the filling body, the mine return air with waste heat is introduced into the pipeline after dust removal, and its heat is used to accelerate the dehydration and consolidation of the filling body. At the same time, the water migration path is regulated, and the water seeping from the filling body is output and recovered through the pipeline, so as to realize the secondary utilization of mine water, improve the density and early strength of the filling body, and have the characteristics of economic energy saving, green environmental protection, and high dehydration efficiency.

[0046] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0047] Reference Figures 1 to 12 As shown, an embodiment of the present invention provides a return air waste heat circulation consolidation system for coal slime-based filling materials, comprising an induced draft device 1, an insulation pipe 2, a gas diversion device 3, a relay fan 4, a heat exchange pipe 5, and a water storage device 6; the induced draft device 1 is arranged at the bottom of the return air shaft 7, and is connected to the gas diversion device 3 through the insulation pipe 2, and the gas diversion device 3 is used to divert hot air into the heat exchange pipes 5 at different positions; the heat exchange pipes 5 are pre-arranged between coal pillars before filling, and a water-permeable groove 51 is opened on the upper part; the water storage device 6 is arranged at the end of the heat exchange pipe 5; when the transportation distance is long, one or more relay fans 4 are arranged on the insulation pipe 2, and the relay fans 4 supplement the power for the airflow in the middle of the pipe.

[0048] In a specific embodiment, Figures 2 to 5 As shown, the air induction device 1 includes a device body, a fan rotating in the device body, and a fan connected to the fan. The device body has a circular air inlet and a square air outlet. A filter 11 is installed at the air inlet to intercept impurities such as coal dust and rock dust in the air flow. Furthermore, a high-pressure spray gun 12 is installed inside the air inlet of the device body. The high-pressure spray gun 12 is used to spray high-pressure gas or liquid during non-working hours to clean impurities accumulated on the filter 11.

[0049] The draft device 1 is used to introduce airflow into the insulated pipe 2, and the insulated pipe 2 is connected between the draft device 1 and the relay fan 4 / gas diversion device 3 to reduce the heat loss of the hot air flow. Since impurities such as coal dust and rock dust exist in the air flow, a filter 11 is installed at the air inlet of the draft device 1 to intercept impurities. Long-term operation will cause dust accumulation to block the filter 11, resulting in reduced draft efficiency. For this reason, a high-pressure spray gun 12 is arranged inside the air inlet to spray high-pressure gas or liquid. The blocked filter 11 is regularly cleaned during non-working hours, and the filter 11 is removable and replaceable.

[0050] In a specific embodiment, Figure 6 and Figure 7As shown, the gas diversion device 3 has an annular pressure balance chamber 31, which is located inside the gas diversion device 3 and is used to expand the flow area of ​​the wind flow; by expanding the flow area, the dynamic pressure of the wind flow is converted into static pressure, thereby reducing the wind speed and wind pressure of the wind flow; this design can effectively avoid excessive wind speed in the heat exchange pipe 5 due to excessive wind pressure, thereby reducing the heat exchange efficiency and water seepage effect between the hot wind flow and the filling material. The annular pressure balance chamber 31 is connected to multiple heat exchange pipes 5, and a porous plate 32 is installed between the annular pressure balance chamber 31 and the heat exchange pipe 5. The porous plate 32 is provided with a plurality of through holes for further regulating the flow and distribution of the wind flow. At the same time, a regulating valve 33 is connected to one side of each porous plate 32, and the regulating valve 33 is used to control the number of passages in the porous plate 32. By adjusting the opening and closing degree of the regulating valve 33, the flow of the wind flow can be quantitatively regulated, thereby realizing the distribution of the wind flow to different heat exchange pipes 5.

[0051] As can be seen from the above structure, the gas diversion device 3 is connected between the insulation pipe 2 and the heat exchange pipe 5, and is used to divert the wind flow. Too high wind pressure in the heat exchange pipe 5 will lead to excessive wind speed, thereby reducing the drying and water seepage effect. Therefore, an annular pressure balance chamber 31 is set inside the diversion device, and the wind speed is reduced by expanding the flow area, reducing the wind pressure in the heat exchange pipe 5, and a porous plate 32 is set between the balance chamber and the heat exchange pipe 5. The number of passages in the porous plate 32 is controlled by the regulating valve 33 to achieve quantitative regulation of the wind flow. The gas diversion device 3 realizes precise regulation of the flow and wind pressure of the hot air flow through the combined design of the annular pressure balance chamber 31, the porous plate 32 and the regulating valve 33. It can effectively avoid the problem of excessive wind speed caused by excessive wind pressure in the heat exchange pipe 5, and at the same time, the quantitative distribution of the wind flow is achieved through the regulating valve 33, which improves the flexibility and applicability of the system.

[0052] In a specific embodiment, Figure 8 and Fig. 9 As shown, the heat exchange pipe 5 includes a pipe body, and the material of the pipe body is aluminum alloy, which has high strength and good thermal conductivity. A water-permeable groove 51 is provided on the upper part of the pipe body, and the water-permeable groove 51 extends along the axial direction of the pipe body. A layer of water-permeable and non-slurry-permeable material is installed in the middle of the water-permeable groove 51 to prevent solid particles from entering the pipe. The entire water-permeable groove 51 is used to collect excess water seeping out of the coal slime-based filling material. Specifically, the water-permeable and non-slurry-permeable material is a geotextile 53, and a layer of wire mesh 54 is installed on the upper and lower parts of the geotextile 53. A coating is applied on the surface of the wire mesh 54 to improve its wettability and promote drainage. The wire mesh 54 is installed on the upper and lower sides of the water-permeable groove 51 to support the geotextile 53 and prevent it from being crushed. The mesh size of the wire mesh 54 is designed to allow water to pass through while preventing most solid particles from entering the pipe.

[0053] To further optimize the scheme, the mesh size design formula is as follows:

[0054] d net ≤k×d interception

[0055] Where, d net is the mesh size, mm; k is the safety margin factor, which is 0.7 to 0.9; d interception The key interception size is D30 (equivalent particle size corresponding to the cumulative particle size distribution percentage of solid particles reaching 30%). Slurry particles with a particle size smaller than D30 can form a filter cake layer on the mesh, further blocking the entry of solid particles and avoiding the problem of pipe blockage. At the same time, under the action of air pressure, the filter cake is prevented from continuously thickening and affecting water permeability.

[0056] Further optimization scheme, two rows of water holes 52 are arranged on both sides of the water permeable groove 51, and each row includes a plurality of water permeable holes 52 arranged equidistantly along the length direction of the heat exchange pipe 5. In this embodiment, the number of the two rows of water permeable holes 52 is the same, and the positions correspond to each other. The structure of a single water permeable hole 52 is similar to that of the water permeable groove 51, and both include a layer of geotextile 53 and two layers of wire mesh 54 distributed above and below the geotextile 53. The mesh design of the wire mesh 54 is consistent with that of the water permeable groove 51.

[0057] To further optimize the solution, the heat exchange pipe 5 is arranged in the middle and lower part of the filling body in the goaf, with an inclination angle of 2 to 5 degrees, so as to heat and dry the filling body and provide conditions for the water that penetrates into the pipe to flow to the water storage device 6 by gravity. The outer diameter of the heat exchange pipe 55 is 1 / 8 to 1 / 10 of the height of the goaf to reduce its influence on the strength of the filling body.

[0058] In a specific embodiment, Figure 1 and Fig.11 As shown, the water storage device 6 is connected to the end of the heat exchange pipe 5, and is used to store the water seeping out of the filling body. A liquid level sensor 61 and a drain valve 62 are installed inside the water storage device 6. An exhaust port 63 that can filter the wind flow is arranged above the liquid level sensor 61, and works together with the water below to reduce the content of harmful gases or dust in the wind flow. When the liquid reserve is too much, the drain valve 62 is automatically opened to discharge the water through the drain port. The drain port is arranged at a height of 1 / 4 upward from the bottom of the water storage device 6, which can reduce the discharge of bottom sediment. The bottom plate of the water storage device 6 is detachable, and the sediment is cleaned separately during non-working hours.

[0059] The working principle of the embodiment of the present invention is as follows:

[0060] The hot air flow at the bottom of the return air shaft 7 is filtered by the induced draft device 1 and then introduced into the insulation pipe 2. When there is too much coal dust and rock dust accumulated in the induced draft device 1, it can be cleaned by a high-pressure spray gun 12. The hot air flow is transported to the filling working surface in the insulation pipe 2, and the insulation pipe 2 can effectively reduce the heat loss of the air flow during the flow of the pipe. After the hot air flow reaches the working surface, the gas diversion device 3 regulates the flow rate and wind pressure, and diverts it to different heat exchange pipes 5. The hot air flow entering the heat exchange pipe 5 uses its own temperature to exchange heat with the coal slime-based filling material, thereby accelerating the drying and consolidation speed of the filling material. The air flow is discharged after filtering, and the moisture seeping from the filling material can enter the pipe through the water permeable groove 51 on the upper part of the heat exchange pipe 5, and is transported to the water storage device 6 at the end of the heat exchange pipe 5 along with the air flow to achieve secondary utilization.

[0061] Compared with the prior art, the embodiment of the present invention provides a return air waste heat circulation consolidation system for coal slime-based filling materials, which can filter impurities in the airflow and avoid the accumulation of impurities that affect efficiency. The system transports the higher-temperature mine return air to the working face, and after the flow rate and wind pressure are regulated by the annular diversion device, it directly exchanges heat with the coal slime-based filling materials, thereby accelerating the drying and consolidation speed of the filling materials and indirectly improving the recovery efficiency. At the same time, the water seeping out of the filling material is transported to the water storage device 6 through the heat exchange pipe 5, realizing the reuse of mine water resources and reducing the impact on the environment during the mining process. The system has the characteristics of economy and energy saving, green and environmental protection, high utilization rate of return air waste heat, good consolidation effect of coal slime-based filling materials, low construction difficulty, and no pollution, which meets the needs of sustainable development.

[0062] In the description of the present invention, it should be understood that the terms "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0063] The embodiments described above are only descriptions of the preferred modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A return air waste heat circulation consolidation system for coal slime-based filling materials, characterized in that: The invention comprises a plurality of heat exchange pipes (5) pre-buried in the filling body between the coal pillars, wherein the upper part of the heat exchange pipes (5) is arranged in a water permeable groove (51) for accelerating the dehydration and consolidation of the coal slime-based filling material and collecting the seeping water; the heat exchange pipes (5) are all connected to the same gas diversion device (3), and the gas diversion device (3) is connected to the air induction device (1) through the insulation pipe (2); the air induction device (1) is arranged at the bottom of the return air shaft (7) for introducing the mine return air containing waste heat; the end of the heat exchange pipe (5) is connected to a water storage device (6) for storing the recovered water and realizing secondary utilization.

2. The return air waste heat circulation consolidation system for coal slime-based filling materials according to claim 1, characterized in that: At least one relay fan (4) is arranged at a preset distance along the length direction of the heat-insulating pipe (2).

3. The return air waste heat circulation consolidation system for coal slime-based filling materials according to claim 1, characterized in that: The air inducing device (1) comprises: A filter screen (11) is detachably mounted at the air inlet of the air induction device (1) and is used to intercept solid particles in the air flow; A high-pressure spray gun (12) is detachably connected to the inner side of the air inlet of the air induction device (1) and is used to clean the filter screen (11).

4. The return air waste heat circulation consolidation system for coal slime-based filling materials according to claim 1, characterized in that: The gas flow distribution device (3) has an annular pressure balance chamber (31), and one end of each of the heat exchange pipes (5) is connected to the annular pressure balance chamber (31).

5. The return air waste heat circulation consolidation system for coal slime-based filling materials according to claim 4, characterized in that: A porous plate (32) is provided at the connection position between the annular pressure balance chamber (31) and the heat exchange pipe (5), and a plurality of through holes are provided on the porous plate (32) for regulating the flow rate and distribution of the wind flow.

6. The return air waste heat circulation consolidation system for coal slime-based filling materials according to claim 5, characterized in that: One side of each of the porous plates (32) is connected to a regulating valve (33), and the regulating valve (33) is used to control the number of passages in the porous plate (32) to achieve airflow distribution for different heat exchange pipes (5).

7. The return air waste heat circulation consolidation system for coal slime-based filling materials according to claim 1, characterized in that: The heat exchange pipe (5) is arranged obliquely in the middle and lower part of the filling body of the goaf, and the inclination angle is 2 to 5 degrees.

8. The return air waste heat circulation consolidation system for coal slime-based filling materials according to claim 7, characterized in that: The outer diameter of the heat exchange pipe (5) is 1 / 8 to 1 / 10 of the height of the goaf.

9. The return air waste heat circulation consolidation system for coal slime-based filling materials according to claim 1, characterized in that: A water-permeable groove (51) is provided on the upper part of the heat exchange pipe (5), and the water-permeable groove (51) extends along the length direction of the heat exchange pipe (5). A layer of geotextile (53) is installed in the middle of the water-permeable groove (51), and a layer of wire mesh (54) is installed above and below the geotextile (53).

10. The return air waste heat circulation consolidation system for coal slime-based filling materials according to claim 9, characterized in that: The mesh size of the wire mesh (54) satisfies the formula: d net ≤k×d interception ; Among them, d net is the mesh size of the wire mesh (54), k is the safety margin factor, which is 0.7 to 0.9, d interception It is the equivalent particle size of D30 particles in coal slime-based filling materials.

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