A method for filling and grouting in a salt mine underground goaf

Abstract

The application provides a method for filling and grouting in a salt mine underground goaf, wherein a nozzle of a grouting pipe column is lowered into sediment in the goaf, a first-stage waste mud is injected into a gap in the sediment in the goaf, the particle diameter of the first-stage waste mud is between 0.001 and 0.05 mm, the grouting pipe column is lifted to a space of pure brine in the goaf, a second-stage waste mud is injected into the space of pure brine in the goaf, the particle size of the second-stage waste mud is not more than 1 cm, a non-uniformity coefficient is greater than or equal to 5, and a curvature coefficient is between 1 and 3, the grouting pipe column is lifted to a roof of the goaf and a "neck", a third-stage waste mud is injected into the roof of the goaf and the "neck", the third-stage waste mud contains a cementing material with a mass fraction of 3% to 10%, and the method can efficiently fill a gap in the sediment at the bottom of the goaf of the salt mine, thereby improving the filling efficiency of the waste in the goaf of the salt mine.

Description

Technical Field

[0001] This invention relates to the field of underground goaf treatment and waste disposal technology in salt mines, and particularly to a method for filling and grouting underground goaf areas in salt mines. Background Technology

[0002] With the development of society and the economy, various industries have generated a large amount of waste during their rapid development. At the same time, people also generate a large amount of waste in their daily lives. The physicochemical composition of these wastes is extremely complex and contains many toxic and harmful substances. However, traditional methods of treating and disposing of these wastes cannot fundamentally isolate them from the biosphere. Methods such as surface accumulation, shallow landfill, incineration, or chemical treatment cannot completely eliminate the impact of these pollutants on the ecological environment. Salt rock, with its low permeability, good metamorphic ability, and self-healing properties, is an excellent geological storage medium. Utilizing salt mine goaf filling for waste disposal can not only eliminate the geological safety hazards inherent in the goaf itself but also enable large-scale disposal of various wastes.

[0003] Salt layers contain a considerable amount of insoluble matter, and are interspersed with varying numbers and thicknesses of sparingly soluble and insoluble interlayers. This results in a large accumulation of insoluble debris and lumps at the bottom of the goaf after leaching salt mines. These materials are deposited in a loose, dispersed manner, containing numerous interconnected voids. Researching grouting and backfilling methods suitable for high-impurity salt mine goafs will be of great significance for the efficient management of salt mine goafs and the large-scale disposal of waste from these goafs. Summary of the Invention

[0004] This invention provides a method for filling and grouting underground goaf areas in salt mines, which can fill the voids in the sediment at the bottom of the goaf areas. This is of great significance for the efficient management of goaf areas in salt mines and the large-scale disposal of waste in goaf areas.

[0005] This invention provides a method for grouting to fill underground goaf areas in salt mines, comprising:

[0006] The inlet of the grouting pipe is lowered into the goaf sediment or onto the upper surface of the sediment, and the first-stage waste mud is injected into the voids in the goaf sediment through the grouting pipe; the particle diameter of the first-stage waste mud is between 0.001 and 0.05 mm.

[0007] The grouting pipe column is raised to the clean brine space of the goaf, and the second-stage waste mud is injected into the clean brine space of the goaf through the grouting pipe column; the particle size of the second-stage waste mud does not exceed 1cm, the non-uniformity coefficient is ≥5, and the curvature coefficient is 1~3;

[0008] The grouting pipe column is raised to the top of the goaf and the "neck" of the goaf, and the third-stage waste mud is injected into the top of the goaf and the "neck" through the grouting pipe column; the third-stage waste mud contains 3% to 10% cementitious material by mass.

[0009] Specifically, during the process of injecting the first-stage waste slurry into the voids in the goaf sediment through the grouting pipe string, the injection flow rate of the first-stage waste slurry is 10~30m³. 3 / h.

[0010] Specifically, raising the grouting pipe column to the clean brine space in the goaf includes:

[0011] Monitor the grouting pressure of the waste mud from the first stage;

[0012] If the grouting pressure rises by at least 2 MPa within 30 minutes, grouting is stopped, and the grouting pipe is raised to the clean brine space in the goaf.

[0013] Specifically, during the process of injecting the second-stage waste mud into the clean brine space of the goaf through the grouting pipe column, the injection flow rate of the second-stage waste mud is 60~120m³. 3 / h, and it is continuous grouting.

[0014] Specifically, the cementing material is cement and / or gypsum.

[0015] One or more technical solutions provided in this invention have at least the following technical effects or advantages:

[0016] First, the grouting pipe is lowered into the goaf sediment, and the first-stage waste mud is injected into the voids in the goaf sediment through the grouting pipe; the particle diameter of the first-stage waste mud is between 0.001 and 0.05 mm. Then, the grouting pipe is raised to the clean brine space in the goaf, and the second-stage waste mud is injected into the clean brine space through the grouting pipe; the particle size of the second-stage waste mud does not exceed 1 cm, the non-uniformity coefficient is ≥5, and the curvature coefficient is [missing value]. Steps 1-3: Finally, the grouting pipe column is raised to the top and "neck" of the goaf. The third-stage waste slurry is injected into the top and "neck" of the goaf through the grouting pipe column. This third-stage waste slurry contains 3%-10% cementitious material by mass, which can efficiently fill the voids in the sediment at the bottom of the salt mine goaf, thereby improving the filling efficiency of waste in the salt mine goaf. This is of great significance for the efficient management of salt mine goafs and the large-scale disposal of waste in salt mine goafs. Furthermore, this invention can fill and dispose of various types of waste, without being limited by the type of waste. Attached Figure Description

[0017] Figure 1 A flowchart illustrating a method for filling and grouting underground goaf areas in salt mines, provided in an embodiment of the present invention;

[0018] Figure 2 This is a schematic diagram of the grouting circulation ground facility in an embodiment of the present invention;

[0019] Figure 3 This is a schematic diagram of the first stage of grouting and filling in the goaf in an embodiment of the present invention;

[0020] Figure 4 This is a schematic diagram of the second stage of grouting and filling in the goaf in an embodiment of the present invention;

[0021] Figure 5 This is a schematic diagram of the third stage of grouting and filling in the goaf in an embodiment of the present invention;

[0022] In the diagram, 1-salt mine goaf, 2-sludge, 3-clean brine space, 4-goaf roof, 5-"neck", 6-shaft, 7-grouting pipe string, 8-brine discharge pipe string, 9-ground surface, 10-slurry preparation and grouting facilities, 11-brine treatment facilities, 12-first stage waste mud, 13-second stage waste mud, 14-third stage waste mud, 15-interface between waste accumulation and brine. Detailed Implementation

[0023] This invention provides a method for filling and grouting underground goaf areas in salt mines. This method can fill the voids in the sediment at the bottom of the goaf areas, which is of great significance for the efficient management of goaf areas in salt mines and the large-scale disposal of waste in goaf areas.

[0024] The technical solutions in the embodiments of the present invention are designed to achieve the above-mentioned technical effects, and the overall concept is as follows:

[0025] Before describing the embodiments of the present invention, the underground goaf area of ​​the salt mine will be described first:

[0026] This invention primarily addresses goaf areas created through water-soluble mining in salt mines. These goaf areas can also be referred to as salt cavities or salt pits. Water-soluble mining technology involves drilling one or more wells from the surface into the underground salt layer. A varying number of casings are installed within the wells. Fresh water is injected into the underground salt layer through these casings. The injected fresh water dissolves the salt layer, forming brine. Under the pressure of the formation and the subsequent injection of fresh water, the brine is discharged to the surface through a tubing string (different from the injected casing) within the well. Through continuous injection and discharge of fresh water, goaf areas are eventually formed within the underground salt layer. For high-impurity salt mines below the surface, after water-soluble mining, a large amount of insoluble material accumulates at the bottom of the goaf area; this insoluble material is called sediment. The sediment accumulates in loose form at the bottom of the goaf, and many interconnected voids exist within the sediment, which are occupied by saturated brine. The remaining spaces within the goaf are completely filled with saturated brine; these spaces are called net brine spaces. The clean brine space is located above the sediment. The goaf roof is the uppermost boundary of the clean brine space, while the "neck" refers to the part connecting the shaft and the goaf roof. This part is not lined with casing and cement, and is in a "bare" state.

[0027] When disposing of solid waste in goaf areas of high-impurity salt mines, the solid waste needs to be crushed and mixed with saturated brine to make slurry, which is then injected into the goaf area. After entering the goaf area, the solid waste settles and accumulates there, and the brine in the goaf area is discharged to the surface.

[0028] To more efficiently inject solid waste slurry into the goaf of a high-impurity salt mine and provide better support, the following method for grouting and filling goafs in high-impurity salt mines is proposed. This method consists of three steps:

[0029] Step 1:

[0030] First, the inlet of the grouting pipe is placed at the sediment surface at the bottom of the salt chamber. At this stage, the particle size of the solid waste must be sufficiently small (less than 0.1 mm), and the slurry must have good stability, meaning the solid particles do not easily settle and can flow freely with the liquid. This allows the waste particles to move a certain distance within the sediment voids, discharging the brine from these voids. Ultimately, the waste particles fill the sediment voids, providing a certain degree of filling and reinforcement to the sediment mass. During this stage, a low-flow grouting method is recommended to achieve better filling results.

[0031] Step Two:

[0032] After the sediment voids are filled, the grouting pipe is raised into the clean brine space. Depending on the size of the clean brine space, this stage of grouting may require multiple grouting operations. During this stage, the solid waste particle size distribution must be good. Such filling material has good mechanical properties and drainage performance, providing better support to the surrounding rock of the salt mine goaf after injection. Continuous grouting is essential during this stage; prolonged pump stoppages are unacceptable. Simultaneously, a low-flow grouting method is used to allow sufficient drainage time for the sediment at the bottom of the salt cavity and the filling material in the clean brine space, ultimately achieving a better filling effect.

[0033] Step 3:

[0034] After the above two grouting steps, most of the space within the goaf is filled and occupied by solid waste, leaving only the space near the goaf roof and the "neck" above the goaf unfilled. Step three is mainly used to fill these spaces above the goaf. From the perspective of long-term safety in disposing of waste in salt mine goafs, after filling, no liquid near the goaf roof should be completely displaced to the surface by the filling material. Ultimately, the filling material should be in direct contact with the goaf roof, with a gap between them. To achieve this, the grouting material must contain a certain amount of cementing material, such as cement or gypsum, in this grouting stage. When the waste containing cementing material enters the goaf roof and the "neck," over time, these materials will solidify and bond near the goaf roof and within the "neck," ultimately achieving the desired effect of supporting the goaf roof and sealing the "neck."

[0035] Through the above three steps of grouting and filling, more waste is filled into the goaf of the salt mine, providing better support for the goaf.

[0036] To better understand the above technical solutions, the following will provide a detailed explanation of the technical solutions in conjunction with the accompanying drawings and specific implementation methods.

[0037] See Figure 1 The method for filling and grouting underground goaf areas in salt mines provided in this embodiment of the invention includes:

[0038] Step S110: Lower the inlet of the grouting pipe column into the goaf sediment or onto the upper surface of the sediment, and inject the first-stage waste mud into the voids in the goaf sediment through the grouting pipe column; the particle diameter of the first-stage waste mud is between 0.001 and 0.05 mm.

[0039] To achieve better filling results, the injection flow rate of the first-stage waste slurry is 10-30 m³ / h during the process of injecting the first-stage waste slurry into the voids in the goaf sediment through the grouting pipe column. 3 / h.

[0040] Step S120: Raise the grouting pipe column to the clean brine space in the goaf, and inject the second-stage waste mud into the clean brine space in the goaf through the grouting pipe column; the solid particles of the second-stage waste mud have good gradation, the particle size does not exceed 1cm, the non-uniformity coefficient is ≥5, and the curvature coefficient is 1~3.

[0041] Specifically, raising the grouting string to the clean brine space in the goaf includes:

[0042] The grouting pressure of the first-stage waste slurry is monitored; specifically, the grouting pressure of the first-stage waste slurry can be monitored in real time by monitoring the pressure reading on the pressure pump at the outlet of the ground grouting pump.

[0043] If the grouting pressure rises by at least 2 MPa within 30 minutes, grouting should be stopped, and the grouting pipe should be raised to the clean brine space in the goaf.

[0044] To allow sufficient drainage time for the sediment at the bottom of the goaf and the filling material in the clean brine space, thereby achieving a better filling effect, the injection flow rate of the second-stage waste mud into the clean brine space of the goaf through the grouting pipe column is 60~120m³. 3 / h, and it is continuous grouting.

[0045] Step S130: Raise the grouting pipe column to the top of the goaf and the "neck" and inject the third-stage waste mud into the top of the goaf and the "neck" through the grouting pipe column; the third-stage waste mud contains 3% to 10% cementitious material by mass.

[0046] In this embodiment, the cementitious material is cement and / or gypsum. When the cementitious material includes cement and gypsum, the total mass fraction of cement and gypsum is between 3% and 10%.

[0047] The embodiments of the present invention will be further described below with reference to the accompanying drawings:

[0048] like Figure 2As shown, the entire salt mine goaf 1 consists of three parts: sediment 2, clean brine space 3, and "neck" 5. To successfully inject waste slurry into the salt mine goaf 1, a slurry preparation and grouting facility 10 and a brine treatment facility 11 must be constructed on the surface 9. The slurry preparation and grouting facility 10 is used to prepare the waste into first-stage waste slurry 12, second-stage waste slurry 13, and third-stage waste slurry 14, and then transport the prepared waste slurry into the salt mine goaf 1 via a surface grouting pump and a grouting pipe string 7 located in the shaft 6. The slurry preparation and grouting facility 10 consists of a waste slurry mixing and preparation device, a temporary slurry storage device, a grouting pump, and grouting pipes. The slurry prepared by the waste slurry mixing and preparation device flows into the temporary slurry storage device through pipelines under the influence of gravity. The slurry from the temporary slurry storage device is then injected into the grouting pipe string 7 located inside the wellbore 6 by the grouting pump through the ground grouting pipeline, and finally flows into the salt mine goaf 1 through the grouting pipe string 7. The waste slurry mixing and preparation device can be a JW1000 vertical concrete mixer manufactured by Zhengzhou Yuke Machinery Equipment Co., Ltd., the temporary slurry storage device can be a 22 cubic meter vertical pre-mixed mortar storage tank manufactured by Zhengzhou Pinchuang Machinery Equipment Co., Ltd., and the grouting pump can be a G-type continuously variable screw pump manufactured by Shanghai Sunshine Pump Industry. Other similar types of equipment can also be used.

[0049] The grouting process in the entire goaf is generally completed in three stages, as follows:

[0050] The first stage of the grouting and filling process in the goaf: (e.g.) Figure 3 As shown, in this grouting process, the inlet of the grouting pipe column 7 is first placed on the upper surface of the sediment 2 at the bottom of the salt mine goaf 1 or inside the sediment 2. The gate valves of the grouting pipe column 7 and the brine discharge pipe column 8 located at the ground surface 9 are opened. The first-stage waste mud slurry 12 is injected into the voids within the sediment 2 through the slurry preparation and grouting facility 10 and the grouting pipe column 7. After entering the voids within the sediment 2, the first-stage waste mud slurry 12 displaces the original brine within the voids. The displaced brine flows through the brine discharge pipe column 8 into the brine treatment facility 11 on the ground surface 9. This brine can be used for other purposes. In this stage, the first-stage waste mud slurry 12 is required to have the following characteristics: the particles of the first-stage waste mud slurry 12 must be small enough so that the solid particles in the first-stage waste mud slurry 12 can move a greater distance within the voids of the sediment 2. The end of this stage is marked by a sharp increase in ground grouting pressure, specifically an increase of at least 2 MPa within 30 minutes.

[0051] The second stage of the grouting and filling process in the goaf: (as follows) Figure 4As shown, after the completion of the first stage, during the grouting process, the grouting pipe column 7 is raised to a certain depth within the clean brine space 3. The second-stage waste mud slurry 13 is injected into the clean brine space 3 through the slurry preparation and grouting facilities 10 and the grouting pipe column 7, displacing the original brine within the clean brine space 3. The displaced brine enters the brine treatment facility 11 on the ground surface 9 through the brine discharge pipe column 8. This brine can be used for other purposes. In this stage, the second-stage waste mud slurry 13 is required to have the following characteristics: good solid particle size distribution, particle size not exceeding 1 cm, non-uniformity coefficient ≥ 5, and curvature coefficient of 1~3. Such waste mud, after being injected into the salt mine goaf 1, can provide better support. During this stage, grouting must be continuous, and prolonged pump stoppages are not permitted. The end of this stage is marked by monitoring the interface 15 between the waste accumulation and the brine using a sonar measuring device until this interface is located at the lowest point of the goaf roof 4.

[0052] The third stage of the grouting and filling process in the goaf: (e.g.) Figure 5 As shown, after the completion of stage two above, during the grouting process, the grouting pipe column 7 is raised to the location of the goaf roof 4 and "neck" 5. The waste mud 14 from the third stage is injected into the goaf roof 4 and "neck" 5 through the slurry preparation and grouting facilities 10 and the grouting pipe column 7, displacing the original brine in the goaf roof 4 and "neck" 5. The displaced brine enters the brine treatment facility 11 on the ground through the brine discharge pipe column 8, where it can be used for other purposes. In this stage, the waste mud 14 from the third stage is required to have the following characteristics: the slurry preparation material must contain a certain amount of cementing material. When the waste mud 14 containing cementing material is injected into the goaf roof 4 and "neck" 5, over time, the waste mud 14 from the third stage will solidify and solidify near the goaf roof 4 and "neck" 5, ultimately achieving a good supporting effect on the goaf roof 4. The end of this stage is marked by the interface between the waste accumulation and the brine (15) being located 4-5 meters below the casing shoe. This location can be accurately obtained using downhole measuring devices, such as sonar measuring devices.

[0053] Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including both the preferred embodiments and all changes and modifications falling within the scope of the invention.

[0054] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from the scope of the invention.

[0055] The spirit and scope of the invention are as follows: Thus, if these modifications and variations of the invention fall within the scope of the claims of the invention and their equivalents, the invention is also intended to include these modifications and variations.

Claims

1. A method for grouting and filling underground goaf areas in salt mines, characterized in that, include: The inlet of the grouting pipe is lowered into the goaf sediment or onto the upper surface of the sediment, and the first-stage waste mud is injected into the voids in the goaf sediment through the grouting pipe; the particle diameter of the first-stage waste mud is between 0.001 and 0.05 mm. The grouting pipe column is raised to the clean brine space of the goaf, and the second-stage waste mud is injected into the clean brine space of the goaf through the grouting pipe column; The particle size of the waste sludge in the second stage does not exceed 1cm, the non-uniformity coefficient is ≥5, and the curvature coefficient is 1~3; The grouting pipe column is raised to the top of the goaf and the "neck" of the goaf, and the third-stage waste slurry is injected into the top of the goaf and the "neck" through the grouting pipe column; the third-stage waste slurry contains 3% to 10% cementitious material by mass; it can efficiently fill the voids in the bottom sediment of the salt mine goaf, thereby improving the filling efficiency of waste in the salt mine goaf; at the same time, it can fill and dispose of a variety of wastes, and is not limited by the type of waste.

2. The method for filling and grouting underground goaf areas in salt mines as described in claim 1, characterized in that, During the process of injecting the first-stage waste slurry into the voids in the goaf sediment through the grouting pipe string, the injection flow rate of the first-stage waste slurry is 10~30m³. 3 / h.

3. The method for filling and grouting underground goaf areas in salt mines as described in claim 1, characterized in that, Raising the grouting string to the clean brine space in the goaf includes: Monitor the grouting pressure of the waste mud from the first stage; If the grouting pressure rises by at least 2 MPa within 30 minutes, grouting is stopped, and the grouting pipe is raised to the clean brine space in the goaf.

4. The method for filling and grouting underground goaf areas in salt mines as described in claim 1, characterized in that, During the process of injecting the second-stage waste mud into the clean brine space of the goaf through the grouting pipe string, the injection flow rate of the second-stage waste mud is 60~120m³. 3 / h, and it is continuous grouting.

5. The method for filling and grouting underground goaf areas in salt mines as described in any one of claims 1-4, characterized in that, The cementing material is cement and / or gypsum.

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