Coal mine solid waste treatment method

Abstract

The invention discloses a coal mine solid waste treatment method. The method comprises the following steps: carrying out classification pretreatment on coal gangue, fly ash and tailings; the pretreated coal gangue and coal ash are mixed according to the weight ratio of (3-5): (1-3), an additive A accounting for 1%-10% of the total weight of the mixed material by mass and water accounting for 10%-30% of the total weight of the mixed material by mass are added into the mixed material, and slurry is prepared through mixing; feeding the slurry into a high-temperature and high-pressure reaction kettle, and reacting under the conditions that the temperature is 150-250 DEG C and the pressure is 0.8-1.5 MPa to obtain a reaction product; and cooling, crushing and screening the reaction product to obtain the coal gangue-fly ash cementing material. According to the method, effective utilization of the coal gangue, the fly ash and the tailings can be realized, and the obtained product has relatively high strength and durability.

Description

Technical Field

[0001] The present invention relates to the field of solid waste treatment, and in particular to a method for treating coal mine solid waste. Background Art

[0002] During the coal mining and processing process, a large amount of coal mine solid waste, such as coal gangue, fly ash and tailings, is generated. The treatment of these solid wastes has always been a serious problem facing the coal industry.

[0003] There are many drawbacks in the traditional treatment of coal mine solid waste. For coal gangue, direct stacking is often used for treatment, which not only occupies a large amount of land resources, but also may cause environmental pollution due to problems such as spontaneous combustion, and the useful components in the coal gangue are not effectively utilized, resulting in a waste of resources. If fly ash is not used reasonably, a large amount of discharge into the environment will lead to a decline in air quality, causing harm to human health and the ecological environment, and its potential utilization value is also ignored. Tailings are usually discarded at will. On the one hand, the small amount of useful metal minerals contained in them are not recovered, resulting in a serious loss of resources; on the other hand, when the water content of the tailings is high, it is easy to cause geological disasters such as mudslides, and when the water content is low, it is not effectively and comprehensively utilized, and its stacking also occupies a large amount of land, posing a safety hazard.

[0004] In the prior art, there are few comprehensive treatment methods for gangue, fly ash and tailings, and even if there are some treatment methods, it is difficult to achieve the coordinated and efficient utilization of the three. For example, when mixing gangue and fly ash, there is a lack of scientific ratios and suitable additives, resulting in low strength and poor durability of the finished products, which cannot meet the actual engineering needs. During the treatment process, the recovery technology for useful metal minerals in tailings is immature and the recovery rate is low. At the same time, there is a lack of effective purification measures for the waste gas and wastewater generated during the treatment process, resulting in increased environmental pollution. The remaining waste residue has not been properly solidified, so that the waste residue may pollute the soil and groundwater, and there are safety risks.

[0005] To sum up, the existing technology has many problems in the treatment of coal mine solid waste, which cannot achieve the effective utilization of coal mine solid waste and has caused serious negative impacts on the environment and resources. This is in sharp contrast to the method provided in the embodiments of the present application, which can achieve the effective utilization of coal gangue, fly ash and tailings and the obtained products have high strength and durability. Summary of the invention

[0006] The present invention aims to solve at least one of the problems in the related art to a certain extent. To this end, the purpose of the present invention is to provide a method for treating coal mine solid waste, which can achieve effective utilization of coal gangue, fly ash and tailings, and the resulting product has high strength and durability.

[0007] In order to achieve the above purpose, this application adopts the following technical solutions:

[0008] The present invention provides a method for treating coal mine solid waste, comprising the following steps:

[0009] S1), classify and pre-treat coal gangue, fly ash and tailings;

[0010] S2), mixing the pretreated coal gangue and fly ash in a weight ratio of 3-5:1-3, adding 1%-10% of additive A by weight of the total weight of the mixture and 10%-30% of water by weight of the total weight of the mixture to the mixture to form a slurry;

[0011] S3), sending the slurry into a high temperature and high pressure reactor, reacting at a temperature of 150°C to 250°C and a pressure of 0.8MPa to 1.5MPa to obtain a reaction product;

[0012] S4), cooling, crushing and screening the reaction product to obtain a coal gangue-fly ash cementitious material.

[0013] Furthermore, the additive A is composed of the following components:

[0014] (i) calcium sulfate or calcium hydroxide, wherein the mass percentage of the calcium sulfate or calcium hydroxide to the total weight of the additive A is 30% to 90%;

[0015] (ii) an alkaline earth metal salt compound, wherein the mass percentage of the alkaline earth metal salt compound to the total weight of the additive A is 10% to 70%.

[0016] Furthermore, the water content of the tailings is less than 20%.

[0017] Furthermore, the particle size of the pretreated coal gangue is less than 5 mm.

[0018] Furthermore, the average particle size of the pretreated fly ash is 2 microns to 20 microns.

[0019] Furthermore, the method also includes: recovering useful metal minerals from the tailings.

[0020] Furthermore, it also includes: purifying the waste gas generated during the treatment process; purifying the waste water generated during the treatment process.

[0021] Furthermore, it also includes: solidifying the remaining waste residue.

[0022] The above-mentioned technical scheme provided by the present invention has the following advantages compared with the prior art: high comprehensive utilization of resources, excellent product performance, high strength and durability, significant environmental protection effect, scientific and reasonable process parameters and precise control of reaction conditions. The coal mine solid waste treatment method of the present invention has significant advantages in resource utilization, product performance, environmental protection and process control, and provides an efficient, environmentally friendly and economical solution for the treatment of coal mine solid waste. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a process flow chart of the present invention. DETAILED DESCRIPTION

[0024] For the purpose of the following detailed description, it should be understood that the present invention may adopt various alternative changes and step sequences, unless expressly specified to the contrary. In addition, except in any operating examples, or otherwise indicated, all numbers representing the amount of ingredients used in the specification and claims should be understood to be modified by the term "about" in all cases. Therefore, unless otherwise indicated, the numerical parameters set forth in the following specification and the attached claims are approximate values ​​that vary according to the desired performance to be obtained by the present invention. At least it is not intended to limit the application of the doctrine of equivalents to the scope of the claims, and each numerical parameter should at least be interpreted according to the number of reported significant figures and by applying ordinary rounding techniques.

[0025] Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the invention are approximations, the numerical values ​​set forth in the specific examples are reported as precisely as possible. Any numerical value, however, inherently contains certain errors necessarily resulting from the standard deviation found in their respective testing measurements.

[0026] In addition, it should be understood that any numerical range described herein is intended to include all subranges subsumed therein. For example, a range of "1 to 10" is intended to include all subranges between (and including) the stated minimum value of 1 and the stated maximum value of 10, i.e., having a minimum value equal to or greater than 1 and a maximum value equal to or less than 10.

[0027] like Figure 1 As shown, the present invention provides a method for treating coal mine solid waste, comprising the following steps:

[0028] S1), classify and pre-treat coal gangue, fly ash and tailings;

[0029] S2), mixing the pretreated coal gangue and fly ash in a weight ratio of 3-5:1-3, adding 1%-10% of additive A by weight of the total weight of the mixture and 10%-30% of water by weight of the total weight of the mixture to the mixture to form a slurry;

[0030] S3), sending the slurry into a high temperature and high pressure reactor, reacting at a temperature of 150°C to 250°C and a pressure of 0.8MPa to 1.5MPa to obtain a reaction product;

[0031] S4), cooling, crushing and screening the reaction product to obtain a coal gangue-fly ash cementitious material.

[0032] It should be noted that various reagents used in the present invention can be obtained from commercial channels, for example, they can be purchased from Shanghai MacLean Biochemical Technology Co., Ltd.

[0033] It is understood that the "mass percentage" in the present invention refers to the grams of solute contained in every 100 grams of solution. "ppm" refers to parts per million, that is, the number of solutes contained in one million samples.

[0034] In practical applications, the gangue, fly ash and tailings can be classified and pre-treated before subsequent processing operations. Specifically, different pre-treatments can be performed on the gangue, fly ash and tailings according to their different properties. For example, the gangue can be crushed to a certain particle size range before mixing it with the other two raw materials. For another example, the fly ash can be filtered to remove impurities before mixing it with the other two raw materials.

[0035] It is understandable that the specific value of the "certain particle size range" can be flexibly set according to actual conditions, as long as the performance of the final product can be guaranteed to be stable.

[0036] In practical application, the pretreated gangue and fly ash can be mixed at a weight ratio of 3-5:1-3, and then 1%-10% of additive A and 10%-30% of water are added to form a slurry. It should be noted that due to the different compositions of gangue, fly ash and tailings, the ratio of each raw material should be appropriately adjusted in practical application to optimize the performance of the final product.

[0037] It can be understood that "1% to 10%", "10% to 30%", "3 to 5" and "1 to 3" are all value ranges, that is to say, the above data are not fixed and can be flexibly set according to actual conditions as long as the performance of the final product can be guaranteed to be stable.

[0038] In practical application, the slurry can be fed into a high temperature and high pressure reactor, and reacted at a temperature of 150°C to 250°C and a pressure of 0.8MPa to 1.5MPa to obtain a reaction product. It should be noted that due to the different compositions of coal gangue, fly ash and tailings, the reaction conditions should be appropriately adjusted in practical application to optimize the performance of the final prepared product.

[0039] It can be understood that "150℃~250℃" and "0.8MPa~1.5MPa" are all value ranges, that is to say, the above data are not fixed and can be flexibly set according to actual conditions as long as the performance of the final product can be guaranteed to be stable.

[0040] In practical application, the reaction product can be cooled, crushed and screened to obtain a gangue-fly ash cementitious material. It should be noted that due to the different compositions of gangue, fly ash and tailings, the cooling speed, crushing force and screening standard should be appropriately adjusted in practical application to achieve the best performance of the final prepared product.

[0041] It is understandable that "cooling speed", "crushing force" and "screening standard" are all value ranges, that is, the above data are not fixed and can be flexibly set according to actual conditions as long as the performance of the final product can be guaranteed to be stable.

[0042] In summary, the present invention discloses a method for treating coal mine solid waste, which can achieve effective utilization of coal gangue, fly ash and tailings, and the obtained product has higher strength and durability.

[0043] Furthermore, the additive A is composed of the following components:

[0044] (i) calcium sulfate or calcium hydroxide, wherein the mass percentage of the calcium sulfate or calcium hydroxide to the total weight of the additive A is 30% to 90%;

[0045] (ii) an alkaline earth metal salt compound, wherein the mass percentage of the alkaline earth metal salt compound to the total weight of the additive A is 10% to 70%.

[0046] It should be noted that, due to the different compositions of coal gangue, fly ash and tailings, the composition of additive A should be appropriately adjusted in actual application so that the performance of the final prepared product can be optimized.

[0047] It is understandable that "30% to 90%" and "10% to 70%" are both value ranges, that is, the above data are not fixed and can be flexibly set according to actual conditions as long as the performance of the final product can be guaranteed to be stable.

[0048] Furthermore, the water content of the tailings is less than 20%.

[0049] It should be noted that when the water content of the tailings is higher than 20%, the performance of the final prepared product will be unstable, so it is necessary to control the water content of the tailings to be lower than 20%.

[0050] It is understandable that "20%" is not fixed and can be flexibly set according to actual conditions as long as the performance of the final product can be guaranteed to be stable.

[0051] Furthermore, the particle size of the pretreated coal gangue is less than 5 mm.

[0052] It should be noted that when the particle size of the coal gangue is greater than 5 mm, the performance of the final product will be unstable, so it is necessary to control the particle size of the coal gangue within 5 mm.

[0053] It is understandable that "5 mm" is not fixed and can be flexibly set according to actual conditions as long as the performance of the final product can be guaranteed to be stable.

[0054] Furthermore, the average particle size of the pretreated fly ash is 2 microns to 20 microns.

[0055] It should be noted that when the average particle size of fly ash is not between 2 microns and 20 microns, the performance of the final product will be unstable. Therefore, it is necessary to control the average particle size of fly ash to between 2 microns and 20 microns.

[0056] It is understandable that "2 microns to 20 microns" is not fixed and can be flexibly set according to actual conditions as long as the performance of the final product can be guaranteed to be stable.

[0057] Furthermore, the method also includes: recovering useful metal minerals from the tailings.

[0058] It should be noted that by effectively utilizing tailings, resource utilization can be improved.

[0059] Furthermore, it also includes: purifying the waste gas generated during the treatment process; purifying the waste water generated during the treatment process.

[0060] It should be noted that environmental pollution can be reduced by purifying waste gas and waste water.

[0061] Furthermore, it also includes: solidifying the remaining waste residue.

[0062] It should be noted that by solidifying the remaining waste residue, it can be prevented from causing secondary pollution.

[0063] It should be noted that the "embodiment" or "embodiment" mentioned in the specification, especially the embodiment of a product, means that the specific features, structures or characteristics described in conjunction with the embodiment or embodiment are included in at least one embodiment or embodiment generally stated in the present application. The same expression appearing in multiple places in the specification is not necessarily related to each other.

[0064] The above technical solution provided by the present invention has the following advantages compared with the prior art:

[0065] 1) High comprehensive utilization of resources, synergistic utilization of gangue and fly ash: by mixing the pretreated gangue and fly ash in a specific weight ratio, adding appropriate amounts of additives and water to form a slurry for reaction, a gangue-fly ash cementitious material is finally obtained. This method makes full use of the two coal mine solid wastes, gangue and fly ash, and converts them into valuable cementitious materials, realizing the recycling of resources, reducing dependence on natural raw materials, and reducing production costs. Compared with traditional treatment methods, such as direct accumulation of gangue and simple discharge of fly ash, this method greatly improves the utilization rate of these two solid wastes, avoids the waste of resources, and also reduces the occupation of land resources due to solid waste accumulation. Tailings resource recovery, water content of tailings is controlled, and useful metal minerals are recovered from them. This not only reduces the accumulation of tailings and reduces the potential harm of tailings to the environment, but also realizes the recycling of valuable components in tailings and improves the comprehensive recovery rate of resources. For mining companies, this means that additional economic benefits can be obtained from tailings that were originally considered waste, thereby enhancing the company's resource utilization efficiency and economic benefits.

[0066] 2) Excellent product performance, high strength and durability: The gangue-fly ash cementitious material prepared by high temperature and high pressure reaction has high strength and good durability. During the reaction process, gangue and fly ash undergo a series of physical and chemical reactions under specific temperature, pressure and additives, so that the generated cementitious material has a compact structure and good performance. This high-strength and durable cementitious material can be widely used in engineering fields such as construction and roads, replacing some traditional building materials such as cement, etc., which can not only meet the requirements of engineering for material performance, but also reduce the construction cost of the project, while reducing the pollution to the environment and resource consumption in the cement production process. Particle size control optimizes performance, and the particle size of pretreated gangue is required to be less than 5 mm, and the average particle size of fly ash is controlled at 2 microns to 20 microns. This fine particle size control is conducive to the uniformity of materials during mixing and reaction, and improves the reaction efficiency and stability of product quality. Smaller coal gangue particle size increases its specific surface area, making it more fully in contact with fly ash and additives, and better able to participate in the reaction during the reaction process, thereby improving the performance of cementitious materials. The appropriate fly ash particle size distribution helps it to play a filling and active role in the system, further enhancing the strength and durability of cementitious materials.

[0067] 3) Significant environmental protection effect, waste gas and wastewater purification treatment: During the entire coal mine solid waste treatment process, the generated waste gas and wastewater are purified. This effectively avoids the pollution of the atmosphere, water bodies and soil environment caused by the direct discharge of waste gas and wastewater, and protects the ecological environment and human health. By adopting advanced waste gas purification technology and wastewater treatment technology, harmful substances in the waste gas can be removed so that it can be discharged after meeting the emission standards; wastewater can be recycled or discharged in compliance with the standards after treatment, reducing the waste of water resources and environmental pollution. Waste slag solidification treatment, solidification treatment of the remaining waste slag, reducing the fluidity and toxicity of the waste slag, and preventing it from polluting the soil and groundwater. The solidified waste slag can be stacked or further processed more safely, reducing the potential harm of the waste slag to the environment. At the same time, the solidified waste slag can improve its stability to a certain extent, reduce the risk of safety accidents caused by problems such as waste slag collapse, and ensure the safety and stability of the surrounding environment.

[0068] 4) Scientific and reasonable process parameters and precise control of reaction conditions. The slurry reacts in a high-temperature and high-pressure reactor, with the temperature controlled at 150℃~250℃ and the pressure at 0.8MPa~1.5MPa. This precise control of reaction conditions ensures the smooth progress of the reaction and the stability of product quality. Within this temperature and pressure range, the gangue, fly ash and additives can fully react chemically to generate a cementitious material with the required properties. If the temperature or pressure is too high or too low, it may affect the reaction and the performance of the product. Therefore, scientific and reasonable reaction conditions are one of the key factors to ensure product quality. The additive formula is optimized. Additive A is composed of calcium sulfate or calcium hydroxide and alkaline earth metal salt compounds, and the mass percentage of each component is within a certain range. This optimized additive formula can promote the reaction, adjust the pH of the system, and enhance the performance of the cementitious material during the reaction. Calcium sulfate or calcium hydroxide can provide a calcium source, participate in the reaction to form a hydration product, and improve the strength of the cementitious material; alkaline earth metal salt compounds can improve the performance of the reaction system, promote the interaction between materials, and further optimize the structure and performance of the cementitious material.

[0069] In summary, the coal mine solid waste treatment method of the present invention has significant advantages in resource utilization, product performance, environmental protection and process control, and provides an efficient, environmentally friendly and economical solution for the treatment of coal mine solid waste.

[0070] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A method for treating coal mine solid waste, characterized in that: The method comprises the following steps: S1), classifying and pre-treating gangue, fly ash and tailings; S2), mixing the pre-treated gangue and fly ash in a weight ratio of 3-5:1-3, adding 1%-10% of additive A by weight accounting for the total weight of the mixture and 10%-30% of water by weight accounting for the total weight of the mixture to the mixture to form slurry; S3), sending the slurry into a high-temperature and high-pressure reactor, reacting at a temperature of 150°C-250°C and a pressure of 0.8MPa-1.5MPa to obtain a reaction product; S4), cooling, crushing and screening the reaction product to obtain a gangue-fly ash cementitious material.

2. The method according to claim 1, characterized in that The additive A is composed of the following components: (i) calcium sulfate or calcium hydroxide, the mass percentage of the calcium sulfate or calcium hydroxide accounting for 30% to 90% of the total weight of the additive A; (ii) alkaline earth metal salt compounds, the mass percentage of the alkaline earth metal salt compounds accounting for 10% to 70% of the total weight of the additive A.

3. The method according to claim 1 or 2, characterized in that: The water content of the tailings is less than 20%.

4. The method according to claim 1 or 2, characterized in that: The particle size of the pretreated coal gangue is less than 5 mm.

5. The method according to claim 1 or 2, characterized in that: The average particle size of the pretreated fly ash is 2 microns to 20 microns.

6. The method according to claim 1 or 2, characterized in that: Also includes: Useful metal minerals are recovered from the tailings.

7. The method according to claim 1 or 2, characterized in that: Also includes: Purify the waste gas generated during the treatment process; The wastewater generated during the treatment process is purified.

8. The method according to claim 1 or 2, characterized in that: Also includes: The remaining waste residue is solidified.

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