In-situ gasification method of ground coal gangue hill
Patent Information
- Application Number
- CN202611215798.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-08-12
- Publication Date
- 2026-10-09
AI Technical Summary
例如，煤矸石应用于混凝土骨料，由于煤矸石存在结构孔隙率和吸水率较大，强度低等因素，使得其作为骨料制备的混凝土工作性、强度和耐久性不佳；煤矸石生产水泥，由于煤矸石中含较高的热值，且不稳定，配入生料中会影响炉窑工况，迄今仍未形成大量利用煤矸石生产水泥的方法，如果用煅烧后的煤矸石渣，又受运输半径的限制；煤矸石发电，烟气排放不满足标准，煤矸石发电所产生的粉煤灰含碳量偏高，难以实现其工业应用，并且其所产生的尾矿煤矸石灰渣量大；煤矸石烧制陶瓷、陶粒和制备合成墙体材料，为煤矸石的利用提供了应用途径，但受高成本、工艺复杂、技术不成熟等因素的限制，难以在普通市场上保持竞争力，消耗量非常有限
[0017]经由上述的技术方案可知，与现有技术相比，本发明取得的有益效果至少包括：
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Figure CN122878993A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of bulk solid waste resource utilization technology, and more specifically to an in-situ gasification method for ground coal gangue piles. Background Technology
[0002] Coal gangue is a solid waste generated during coal mining and washing. When it accumulates on the ground, it not only occupies a lot of land, but can also cause environmental pollution due to spontaneous combustion, dust, and heavy metal leakage.
[0003] Currently, the main ways to dispose of or utilize coal gangue include concrete aggregate, cement production, power generation, wall materials, and ceramics. However, given the huge amount of coal gangue generated and stockpiled, the comprehensive utilization rate of coal gangue, especially in terms of large-scale and value-added utilization, is still insufficient. For example, when coal gangue is used as concrete aggregate, its high porosity, water absorption, and low strength result in poor workability, strength, and durability of the concrete. In cement production, the high and unstable calorific value of coal gangue affects furnace operation, preventing the widespread use of it. Using calcined coal gangue slag is also limited by transportation radius constraints. Coal gangue power generation fails to meet emission standards, and the high carbon content of the fly ash hinders its industrial application, while the resulting tailings (coal gangue lime slag) are substantial. While coal gangue can be used to produce ceramics, ceramsite, and synthetic wall materials, these applications are limited by high costs, complex processes, and immature technology, making it uncompetitive in the general market and resulting in very limited consumption.
[0004] Coal gangue is not valued as fuel because of its low calorific value and high ash content; it is not economically viable as an aggregate for various additives because of its poor strength and hardness, and it requires crushing and screening; and it is energy-intensive to extract various metal elements from it because of crushing, leaching, and purification.
[0005] Therefore, traditional methods for the disposal and value-added utilization of coal gangue have problems such as simple processes, single products, poor performance, secondary pollution from tailings, small disposal and utilization volume, and low product added value. Summary of the Invention
[0006] In view of this, and considering the problems of large porosity, poor pressure resistance, and easy collapse of coal gangue piles, this invention provides an in-situ gasification method for ground coal gangue piles, which converts them into high-calorific-value gaseous fuels, rapidly reduces their stock, and pulverizes the hard solids within them for subsequent utilization.
[0007] To achieve the above objectives, the present invention provides an in-situ gasification method for a ground-based coal gangue pile, comprising first enclosing the entire or part of the coal gangue pile, and then constructing a gasification unit by building a construction channel close to the bottom of the coal gangue pile into the enclosed coal gangue pile; the gasification unit includes an air inlet, a gasification channel, and an air outlet connected in sequence, wherein the air inlet and the air outlet are connected to the outside of the coal gangue pile; the method further includes injecting a gasifying agent into the gasification channel through the air inlet, igniting the coal gangue, and collecting the coal gas from the air outlet.
[0008] Preferably, a screen pipe is laid in the gasification channel.
[0009] Preferably, the screen tube is made of metal or concrete, has a temperature resistance range of 800~1000℃, an inner diameter of ≥100mm, and has openings with an opening rate of 5%~30% and a maximum width of ≤10mm.
[0010] Preferably, the enclosed coal gangue pile has a length ≥100m, a width ≥40m, and a height ≥1.5m.
[0011] Preferably, the process of enclosing the entire or part of the coal gangue pile specifically involves applying a sealing and curing agent to the surface of the coal gangue pile; or laying a temperature-resistant, pressure-resistant, and airtight sheet on the top of the coal gangue pile, with the edges of the sheet inserted downwards to the bottom of the coal gangue pile.
[0012] Preferably, the sealing and curing agent is a penetrating sealing and curing material.
[0013] Preferably, before applying the sealing and curing agent, a layer of cement concrete or a mixture of fly ash, lime and water is applied to the surface of the coal gangue pile to harden and densify the surface.
[0014] Preferably, the sheet material can be selected from steel plate, sheet metal, plastic film, plastic sealing cloth, or temperature / pressure resistant silicone composite sheet.
[0015] Preferably, before laying the sheet material, support rods are pre-installed in the coal gangue pile. The support rods include support columns and arch rods, which support the sheet material; or air bags are installed on the sheet material, which are inflated and supported by air.
[0016] When laying the sheet, the edge of the sheet is inserted 10-50cm into the bottom of the coal gangue pile, and filler material for reinforcing the sheet is injected into the gap between the sheet and the coal gangue on both sides.
[0017] As can be seen from the above technical solution, compared with the prior art, the beneficial effects achieved by the present invention include at least the following:
[0018] This invention encloses part or all of a coal gangue pile before gasification, preventing the injected gasifying agent and / or the gas generated from combustion and gasification from escaping and causing resource waste or air pollution. The construction of gas channels makes the combustion and gasification of coal gangue controllable. Through combustion and gasification, the volume of the coal gangue pile is greatly reduced, and the generated gas can be used as gaseous fuel or chemical raw material. The ash residue after combustion and crushing has many applications. In this way, large quantities of coal gangue on the ground can be quickly disposed of, realizing the resource utilization of waste. Attached Figure Description
[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.
[0020] Figure 1 A schematic diagram of the boreholes in the enclosed coal gangue pile and its internal gasification unit.
[0021] Figure 2 This is a schematic diagram of a coal gangue pile and its cross-section.
[0022] Figure 3 A schematic diagram of a cross-section of a coal gangue pile sealed with a sealing and curing agent.
[0023] Figure 4 This is a schematic diagram of a trapezoidal coal gangue pile.
[0024] Figure 5 This is a schematic diagram of the cross-section of a coal gangue gasification unit.
[0025] Figure 6 A schematic diagram of a sieve tube structure. Detailed Implementation
[0026] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0027] The entire or part of a coal gangue pile is enclosed, and at least one gasification unit is constructed within the enclosed coal gangue pile. The gasification unit includes an inlet, a gasification channel, and an outlet, which are connected in sequence. The inlet and outlet are connected to the outside environment. Figure 1As shown, screen pipes are laid in the gasification channel inside the coal gangue pile. A gasifying agent is injected into the gasification channel through the air inlet, igniting the coal gangue to achieve incomplete combustion (i.e., gasification). The gas is collected from the air outlet. Enclosing part or all of the coal gangue pile before gasification prevents the injected gasifying agent and / or the gases produced by combustion and gasification from escaping, thus avoiding resource waste or air pollution. Constructing a gas channel makes the combustion and gasification of coal gangue controllable. Through combustion and gasification, the volume of the coal gangue pile is greatly reduced. The generated gas can be used as gaseous fuel or chemical raw material. The ash residue after combustion and crushing has many applications. This allows for the rapid and large-scale disposal of coal gangue on the ground, achieving resource utilization of waste.
[0028] Sealing a coal gangue pile can be achieved by applying a sealing and curing agent to its surface, forming a high-strength, impermeable, hardened shell. The sealing and curing agent, also known as a penetrating sealing and curing material, or concrete sealing and curing agent or chemical dust-proofing hardener, penetrates efficiently and undergoes a complex chemical reaction with some components of the coal gangue, forming a three-dimensional network structure that produces a hard substance, creating a dense, high-strength, and highly wear-resistant shell on the surface of the coal gangue pile. Preferably, before applying the sealing and curing agent, a layer of cement concrete or a mixture of fly ash, lime, and water can be applied to the surface of the coal gangue pile to harden and densify it, preventing the sealing and curing agent from leaking into the deeper parts of the coal gangue pile through the larger pores on the surface, thus reducing the amount of sealing and curing agent needed. The choice of sealing and curing agent, cement concrete, or the mixture of fly ash, lime, and water can be made according to actual needs.
[0029] Enclosing a coal gangue pile can also involve laying a temperature-resistant, pressure-resistant, and airtight sheet on top of the pile, with the edges of the sheet embedded downwards to the bottom. The sheet can be made of steel plate or sheet metal, plastic film, sealing cloth, or temperature / pressure-resistant silicone composite sheet, etc. The sheet forms a large "cover" to seal the portion of the coal gangue pile to be gasified. When the sealed coal gangue decreases significantly in volume due to gasification, to prevent the flexible sheet (e.g., plastic film, sealing cloth, composite silicone, etc.) from collapsing, support rods (including support columns and arches) can be pre-installed in the sealed coal gangue pile. These support columns and arches support the sheet, or air chambers can be installed on the sheet, inflating it to maintain its supported position (an air arch effect).
[0030] When inserting the sheet material into the bottom of the coal gangue pile, the lowest point of the sheet material should be 10-50cm lower than the bottom of the coal gangue pile. At the same time, concrete filler should be injected into the gaps between the sheet material and the coal gangue on both sides to strengthen the stability and airtightness of the sheet material, and at the same time, it can play a role in heat insulation and support.
[0031] Screen pipes are installed in the air inlets, gasification channels, and air outlets inside the coal gangue pile. This is because the interior of the coal gangue pile has high permeability and poor pressure resistance. Once the lower coal gangue burns and forms a combustion sludge zone, the coal gangue at the top of the combustion sludge zone can easily fall, causing blockage or upward movement of the gasification channels (making it difficult for the coal gangue below the gasification channels to burn and gasify, resulting in resource waste). At the same time, the screen pipes installed in the gasification channels also prevent the ash and slag formed by the combustion and gasification of coal gangue from accumulating and blocking the gasification channels. The screen pipes can be made of metal or concrete and can withstand high temperatures of 800~1000℃ for extended periods.
[0032] The inner diameter of the screen tube is not less than 100mm, preferably 300mm~3000mm, and more preferably 1000mm~2000mm, allowing personnel or small equipment to enter for unblocking or maintenance. The maximum width of the openings on the screen tube does not exceed 10mm to prevent falling ash and slag from clogging the air injection pipe or moving equipment inside the screen tube. More preferably, the openings on the screen tube are non-uniformly and symmetrically distributed, such as... Figure 6 As shown, the gas flow can be guided to diffuse in the desired direction within the gasification channel, thereby increasing the gasification and combustion expansion rate of coal gangue in the desired direction.
[0033] The enclosed coal gangue pile must be at least 100m long, at least 40m wide, and at least 1.5m high to ensure that the gasification combustion zone extends to both sides of the gasification channel without reaching the sealing edge, and a heat insulation layer or a coal gangue belt that provides support must be reserved.
[0034] A portion of the collected coal gas is diverted and reinjected into the gasification zone through another gas injection pipe via the air inlet to aid in combustion and gasification. The gasifying agent can be air, oxygen-enriched gas, preferably a mixture of O2, CO2, and / or water vapor. Other specific values, such as the type and concentration of the gasifying agent, can be selected according to actual needs, and will not be elaborated here.
[0035] Example 1
[0036] On a coal gangue mountain approximately 500m long, 100m wide, and 15m high at its highest point (such as...) Figure 2 A layer of cement concrete about 100mm thick is laid on and around the coal gangue pile (as shown in the picture), compacted, and allowed to set. Then, a concrete sealant is applied to the surface of the concrete to form a high-strength, impermeable, hardened shell. The concrete and sealant completely seal the coal gangue pile.
[0037] A miniature tunnel boring machine (TBM) was used to excavate a channel approximately 1000mm in diameter along the length of the coal gangue pile, closely following its bottom. Simultaneously, steel screen pipes were laid within the channel, with an opening ratio of approximately 25% and a maximum aperture of no more than 10mm. From approximately 10m from the surface of the coal gangue pile to the exit of the channel, ordinary oil casing was laid. One end of the casing connected to the screen pipe, and the other end connected to valves and pipelines. The interface between the casing and the coal gangue pile surface was sealed with cement concrete, thus constructing the inlet / outlet and gasification channel for the coal gangue gasification unit. A cross-sectional diagram of the sealed coal gangue gasification unit is shown below. Figure 3 As shown.
[0038] A gas injection pipe is laid through the inlet / outlet port at one end of the gasification unit within the gasification channel of the coal gangue pile. The end of the gas injection pipe is located at a predetermined position. A mixture of oxygen, carbon dioxide, and water vapor is injected into the gasification channel as a gasifying agent through the gas injection pipe, with an oxygen volume fraction of 40% and a water vapor volume fraction of 20%. The gas is then ignited at the predetermined position to burn nearby coal gangue. The injection rate and pressure of the gasifying agent are gradually increased until stable gasification is achieved, at which point the injection rate of the gasifying agent is 7000 Nm³. 3 At a pressure of 0.5 MPa, gasification is implemented. The coal gas produced by combustion and gasification is discharged from the inlet / outlet vents at the other end of the gasification unit, which is to say, in-situ gasification of the coal gangue pile with a backward gas injection point is implemented. In order to make the combustion and gasification of coal gangue more complete, a portion of the produced coal gas is reinjected to the end of the first gas injection pipe through another gas injection pipe. During the gasification process, the pressure difference between the inlet and outlet gas is kept not exceeding 0.1 MPa to ensure that the gasification channel is unobstructed and the gasification stage is stable. The volume percentage of each component in the coal gas is shown in Table 1. It can consume more than ten tons of coal gangue per hour.
[0039] Table 1. Component content (volume percentage%) and calorific value of oxygen-enriched carbon dioxide gasified coal gas
[0040] 21.60 1.00 12.40 64.70 0.00 0.40 1114.10
[0041] Example 2
[0042] As an alternative to Embodiment 1, with the remaining technical details being the same:
[0043] A mixture of fly ash, lime, and water (with a fly ash to lime mass ratio of 7:3 in dry material) is used to replace cement concrete.
[0044] Cement screens with built-in steel reinforcement were used instead of steel screens lining the gasification channel.
[0045] Example 3
[0046] On a trapezoidal coal gangue mountain approximately 1000m long, 500m wide, and 10m high, a coal gangue gasification unit approximately 500m long, 50m wide, and 10m high is constructed along its length over a 50m section. Figure 4 As shown by the dotted line, a sealing cloth is inserted into the coal gangue pile through excavated trenches along the length of the gasification unit. This sealing cloth is pressure-resistant to 1.0 MPa and temperature-resistant to 150℃. The lower edges of the sealing cloth at both ends of the gasification unit are directly inserted below the ground. The bottom edge of the inserted sealing cloth is at least 20 cm lower than the bottom of the coal gangue pile or the ground. Hydraulic concrete is injected on both sides of the sealing cloth to reinforce its sealing performance within the coal gangue pile. A vertical support rod is inserted at intervals above the coal gangue gasification unit into the coal gangue pile, forming an arched support with the horizontal support rods to support the sealing cloth. The sealing cloths above and at both ends of the gasification unit are spliced together to form a sealed sealing cloth canopy, "covering" and sealing the coal gangue within the gasification unit. The cross-section of the gasification unit is shown below. Figure 5 As shown.
[0047] A 300mm diameter channel is drilled along the length of the gasification unit, close to the bottom of the coal gangue pile. Reinforced concrete screen pipes are laid in the channel to construct the gasification channel of the gasification unit. Ordinary oil casing is laid in the gasification channel located inside the coal gangue pile, about 10m away from both sides of the gasification unit and through the plastic sealing cloth to connect with the outside world, to prevent gas escape or leakage. The casing outside the plastic sealing cloth is connected to the gas pipeline through valves to form gas inlet / outlet holes.
[0048] A mixture of oxygen-enriched air (45% oxygen, 25% water vapor) and water vapor is injected into the gasification channel through the inlet / outlet of one end of the gasification unit via an injection pipe. This ignites the coal gangue, initiating a retraction-type gasification process. The gas is then discharged through the inlet / outlet of the other end of the gasification unit. The injection rate of the gasifying agent is gradually increased to 4000 Nm³. 3 The pressure is stabilized at 0.3 MPa per hour, and the pressure difference between the inlet and outlet is kept no greater than 0.1 MPa. The composition and calorific value of the gas during the stable gasification stage are shown in Table 2. Approximately ten tons of coal gangue can be consumed per hour.
[0049] Table 2. Component content (volume percentage%) and calorific value of oxygen-enriched air gasification gas
[0050] 28.33 2.75 10.9 27.03 0.74 30.25 1293.92
[0051] Example 4
[0052] As an alternative to Embodiment 3, with the remaining technical details being the same:
[0053] Start multiple non-adjacent gasification units simultaneously;
[0054] Gasification channels were constructed using pipe jacking technology;
[0055] Use sheet metal instead of plastic wrap;
[0056] Oxygen-enriched carbon dioxide and water vapor are used as gasifying agents, with oxygen volume fraction of 30% and water vapor volume fraction of 20%.
[0057] The vaporizing agent is injected directly into the vaporization channel through the air inlet rather than through the injection pipe. Specific parameters are: the injection rate of the vaporizing agent is 5000 Nm³. 3 / h, pressure stabilized at 0.4MPa, maintaining the pressure difference between the inlet and outlet vents no greater than 0.1MPa, and a portion of the gas produced by gasification (approximately 1000 Nm³) 3 The coal gangue is reinjected into the gasification channel at a rate of / h, where it is burned and gasified together with the coal gangue to improve the quality of the coal gas and stabilize the composition and calorific value of the coal gas during the gasification stage, as shown in Table 3. Each gasification unit can consume about 15 tons of coal gangue per hour, which thoroughly crushes the coal gangue for subsequent use.
[0058] Table 3. Component content (volume percentage%) and calorific value of oxygen-enriched carbon dioxide gasified coal gas.
[0059] 25.65 8.75 12.60 52.29 0.61 0.10 1790.71
[0060] Using multiple gasification units for simultaneous gasification can significantly increase the amount of coal gangue consumed per unit time. Moreover, with multiple gasification units operating simultaneously, gasification can be carried out at intervals. After the gasification of the two gasification units is completed, their plastic sealing cloth is removed, and then the intermediate gasification unit is spliced and sealed to carry out the gasification of the intermediate gasification unit, thus realizing the reuse of the plastic sealing cloth.
[0061] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.
[0062] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims
1. An in-situ gasification method for surface coal gangue piles, characterized in that, This involves first enclosing the entire or part of the coal gangue pile, then constructing a gasification unit by building a construction channel from the bottom of the coal gangue pile into the enclosed pile; the gasification unit includes an air inlet, a gasification channel, and an air outlet connected in sequence, wherein the air inlet and air outlet are connected to the outside of the coal gangue pile; and... include, The gasifying agent is injected into the gasification channel through the air inlet, and the coal gangue is ignited. The coal gas is collected through the air outlet. The vaporizing agent includes air and / or oxygen-enriched gas.
2. The in-situ gasification method for a surface coal gangue pile according to claim 1, characterized in that, A screen pipe is laid in the gasification channel.
3. The in-situ gasification method for a surface coal gangue pile according to claim 2, characterized in that, The screen tube is made of metal or concrete, with a temperature resistance range of 800~1000℃, an inner diameter of ≥100mm, and openings with a maximum width of ≤10mm.
4. The in-situ gasification method for a surface coal gangue pile according to claim 1, characterized in that, The enclosed coal gangue pile has a length of ≥100m, a width of ≥40m, and a height of ≥1.5m.
5. The in-situ gasification method for a surface coal gangue pile according to claim 1, characterized in that, The process of enclosing the entire or part of the coal gangue pile specifically involves applying a sealing and curing agent to the surface of the coal gangue pile; or laying sheets on top of the coal gangue pile with the edges of the sheets inserted downwards to the bottom of the coal gangue pile.
6. The in-situ gasification method for a surface coal gangue pile according to claim 5, characterized in that, The sealing and curing agent is a penetrating sealing and curing material.
7. The in-situ gasification method for a surface coal gangue pile according to claim 5, characterized in that, This also includes applying a layer of cement concrete or a mixture of fly ash, lime and water to the surface of the coal gangue pile before applying the sealant and curing agent.
8. The in-situ gasification method for a surface coal gangue pile according to claim 5, characterized in that, The sheet material can be selected from steel plate, sheet metal, plastic film, plastic sealing cloth, or temperature / pressure resistant silicone composite sheet.
9. The in-situ gasification method for a surface coal gangue pile according to claim 5, characterized in that, It also includes, Before laying the sheet material, support rods are pre-installed in the coal gangue pile. The support rods include support columns and arch rods, which support the sheet material. Alternatively, air chambers can be installed on the sheet to inflate and support it.
10. The in-situ gasification method for a surface coal gangue pile according to claim 5, characterized in that, It also includes, When laying the sheet, the edge of the sheet is inserted 10-50cm into the bottom of the coal gangue pile, and filler is injected into the gap between the sheet and the coal gangue on both sides.