Preparation method and application of multi-source coal-based solid waste filling material

Abstract

The invention provides a preparation method of a multi-source coal-based solid waste filling material, and belongs to the technical field of solid waste reutilization, and the preparation method comprises the following steps: uniformly mixing cement, fly ash, furnace bottom slag, desulfurized gypsum, coal gangue, gasified slag and a water reducing agent to obtain a mixed material; and adding fluorine-containing mine water into the mixed material, stirring and mixing to obtain the cemented multi-source coal-based solid waste filling material with predetermined fluidity and bleeding rate. The invention further provides application of the multi-source coal-based solid waste filling material. According to the preparation method and application of the multi-source coal-based solid waste filling material, the coal-based solid waste can be comprehensively recycled and is environmentally friendly, and the prepared multi-source coal-based solid waste filling material can effectively control and treat fluorine ions in mine water.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of solid waste recycling, in particular to a preparation method and application of a multi-source coal-based solid waste filling material. BACKGROUND

[0002] The state attaches unprecedented importance to environmental protection, proposes to promote energy production, establish a clean, low-carbon, safe and efficient energy system, adhere to the state's basic policy, save resources and protect the environment, and proposes that green mountains and clear rivers are golden mountains and silver mountains, and implements the strictest ecological environment protection system. Developing resource comprehensive utilization is an important content of China's deep implementation of sustainable development strategy. Large solid waste is large in quantity, has a significant environmental impact, and has broad utilization prospects, and is the core field of resource comprehensive utilization. Promoting comprehensive utilization of large solid waste is of great significance to improving resource utilization efficiency, improving environmental quality, and promoting comprehensive green transformation of economic and social development.

[0003] With the rapid development of China's economy and the acceleration of industrialization process, the exploitation and utilization of coal resources are increasingly expanding. However, in this process, a large amount of coal-based solid waste, including coal gangue, gasification slag, fly ash, furnace bottom slag, and desulfurization gypsum, has been generated, causing serious environmental pollution. How to realize efficient utilization and environmentally friendly disposal of coal-based solid waste has become an important issue facing China's environmental protection field.

[0004] Filling material is an important link of cemented filling mining, but the widely used cementing agent is still cement, which is expensive and does not adapt to the characteristics of today's mine filling. Using multi-source coal-based solid waste to prepare filling material can not only solve the environmental problem of coal-based solid waste, but also provide a new environmentally friendly filling product with low cost and high quality. This will help promote the development of China's environmental protection industry, promote resource recycling, and achieve dual benefits of economy and environment.

[0005] China's coal is mainly mined underground, and a large amount of underground gushing water (i.e. coal mine water) is usually generated during coal mining. A series of geological activities caused by coal mining have broken the original hydrogeological conditions and rock group structure of the underground water system, and have damaged the original aquifer structure. Due to water-rock interaction, the mine water has been contaminated to varying degrees. The fluoride content in mine water varies greatly, and the fluoride content in groundwater is generally required to be ≤1 mg / L. The fluoride content in the mine water of some coal mines in China exceeds the standard, with a mass concentration of 1.1-10.0 mg / L. Long-term drinking of high-fluorine water by residents in mining areas can cause different degrees of fluorosis, causing dental fluorosis and skeletal fluorosis, etc., causing serious harm to human health, and the excessive fluoride content has become one of the factors restricting the resource utilization of mine water.

[0006] Therefore, it has important theoretical and practical significance for coal mining in China to study a multi-source coal-based solid waste filling material capable of effectively controlling and treating fluorine ions. SUMMARY

[0007] The technical problem solved by the present application is to provide a preparation method of a multi-source coal-based solid waste filling material capable of effectively controlling and treating fluorine ions in mine water.

[0008] To solve the above technical problems, the present application provides a preparation method of a multi-source coal-based solid waste filling material, comprising the following steps:

[0009] The cement, fly ash, bottom slag, desulfurization gypsum, coal gangue, gasification slag and water reducing agent are stirred and mixed to obtain a mixture;

[0010] The fluorine-containing mine water is added to the mixture and stirred and mixed to obtain a cemented multi-source coal-based solid waste filling material with predetermined fluidity and bleeding rate.

[0011] Further, in the mixture, the cement is 5-8%, the fly ash is 10-20%, the bottom slag is 4-10%, the desulfurization gypsum is 6-10%, the coal gangue is 20-60%, the gasification slag is 10-50%, and the water reducing agent is 0.02-0.10% by mass percentage.

[0012] Further, the cement is P.I 42.5 Portland cement; the water reducing agent includes one or more of sulfate type, polycarboxylic acid type, fatty acid type and phosphate type.

[0013] Further, the cement, fly ash, bottom slag, desulfurization gypsum, coal gangue, gasification slag and water reducing agent are stirred and mixed, and the stirrer used for stirring and mixing the mixture and adding fluorine-containing mine water to the mixture is a JJ-15 type cement mortar stirrer.

[0014] Further, the addition amount of the fluorine-containing mine water is 15-20% of the mass of the mixture.

[0015] Further, the fluorine ion concentration in the fluorine-containing mine water is 2-10 mg / L.

[0016] Further, the fluidity of the cemented multi-source coal-based solid waste filling material is 150-300 mm, and the bleeding rate of the cemented multi-source coal-based solid waste filling material is 2-13%.

[0017] The present application also provides an application of a multi-source coal-based solid waste filling material for filling the goaf in coal mining, comprising:

[0018] In the process of coal mining, the prepared cemented multi-source coal-based solid waste filling material is transported and filled into the goaf.

[0019] The cemented multi-source coal-based solid waste filling material is cured after curing for 3-28 days at normal temperature and normal pressure;

[0020] The cured multi-source coal-based solid waste filling material fixes the fluoride ions in the mine water to reduce the fluoride ion concentration in the leaching solution.

[0021] Further, the compressive strength of the cemented multi-source coal-based solid waste filling material cured after curing for 3 days at normal temperature and normal pressure is 0.8-2.5 MPa, the compressive strength of the cemented multi-source coal-based solid waste filling material cured after curing for 7 days at normal temperature and normal pressure is 1.8-3.5 MPa, and the compressive strength of the cemented multi-source coal-based solid waste filling material cured after curing for 28 days at normal temperature and normal pressure is 2.5-14.0 MPa.

[0022] Further, the fluoride ion concentration in the leaching solution after the fluoride ions in the mine water are fixed by the multi-source coal-based solid waste filling material is ≤1 mg / L.

[0023] The application provides a preparation method of a multi-source coal-based solid waste filling material.

[0024] The application provides a preparation method of a multi-source coal-based solid waste filling material.

[0025] Further, the compressive strength of the cemented multi-source coal-based solid waste filling material cured after curing for 3 days at normal temperature and normal pressure is 0.8-2.5 MPa, the compressive strength of the cemented multi-source coal-based solid waste filling material cured after curing for 7 days at normal temperature and normal pressure is 1.8-3.5 MPa, and the compressive strength of the cemented multi-source coal-based solid waste filling material cured after curing for 28 days at normal temperature and normal pressure is 2.5-14.0 MPa.

[0026] Meanwhile, the calcium ions and the fluorine ions in the prepared multi-source coal-based solid waste filling material are combined to form calcium fluoride precipitates which are non-toxic and insoluble in water and are fixed in the multi-source coal-based solid waste filling material, so that the influence of the fluorine ions on the environment is effectively reduced.

[0027] Therefore, the preparation method and application of the multi-source coal-based solid waste filling material are provided, the green filling material meeting the requirements of mines is prepared, the comprehensive utilization level of the coal-based solid waste is improved, the application of the coal-based solid waste in the mine filling field is promoted, and the fluorine ions in the fluorine-containing mine water are effectively solidified, so that the fluorine pollution is eliminated, the leaching fluorine ion concentration of the filling material after maintenance is less than 1 mg / L, and the national comprehensive wastewater discharge standard is met. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 A preparation method flow chart of the multi-source coal-based solid waste filling material is provided for the embodiments of the present application. DETAILED DESCRIPTION

[0029] Referring to Figure 1 The preparation method of the multi-source coal-based solid waste filling material provided by the embodiments of the present application includes the following steps:

[0030] Step 1) A cement, fly ash, bottom slag, desulfurization gypsum, coal gangue, gasification slag and water reducing agent are taken according to the mass percentage ratio, and are stirred and mixed uniformly to obtain a mixture.

[0031] In the mixture, the cement accounts for 5-8%, the fly ash accounts for 10-20%, the bottom slag accounts for 4-10%, the desulfurization gypsum accounts for 6-10%, the coal gangue accounts for 20-60%, the gasification slag accounts for 10-50%, and the water reducing agent accounts for 0.02-0.10%.

[0032] In the stirring and mixing process of the raw materials, a JJ-15 type cement mortar stirrer is used to stir and mix the raw materials uniformly.

[0033] The cement is P.I 42.5 Portland cement, and the chemical composition and content thereof are shown in Table 1 below:

[0034] Table 1

[0035] SiO2 Al2O3 Fe2O3 CaO MgO SO3 Na2O eq ]]> f-CaO Cl – ]] Loss 20.72 4.62 3.26 62.18 3.15 2.72 0.52 0.72 0.012 1.84

[0036] The gasification slag is a coal gasification coarse slag, the fineness modulus is 1.73, the fineness modulus of the coal gangue is 2.83, and the particle size distribution of the gasification slag and the coal gangue is shown in Table 2 below:

[0037] Table 2

[0038]

[0039]

[0040] The water reducing agent includes one or more of sulfate type water reducing agent, polycarboxylic acid type water reducing agent, fatty acid type water reducing agent, and phosphate type water reducing agent.

[0041] The water reducing agent disperses the agglomerated particles by forming electrostatic repulsion or steric hindrance effect through adsorption on the particle surface, and releases the free water wrapped. An appropriate amount of water reducing agent can disperse the particles, improve water retention, and reduce bleeding rate; but excessive use will cause excessive dispersion of particles, decrease of slurry viscosity, acceleration of aggregate settlement speed, and increase of bleeding rate. Therefore, the mass percentage of water reducing agent in the mixture is controlled at 0.02-0.10%.

[0042] The cement, bottom ash, desulfurization gypsum, and fly ash, etc. as cementitious materials have large specific surface area, strong water adsorption capacity, and good water retention. The more water molecules adsorbed on the surface of the finer cementitious material particles, the more difficult the water molecules are to be released. Therefore, the mass percentage of cement in the mixture is controlled at 5-8%, the mass percentage of bottom ash is controlled at 4-10%, the mass percentage of desulfurization gypsum is controlled at 6-10%, and the mass percentage of fly ash is controlled at 10-20%.

[0043] The gradation, shape, and content of the coal gangue and gasification slag as aggregate: The aggregate with poor gradation (such as single gradation) has large void ratio, and the slurry cannot be fully filled, and the excess water is easily released along the void channel. The larger the particle size of the coarse aggregate, the faster the settlement speed, and the water is released. The higher the content of the aggregate, the thinner the slurry wrapping layer, and the weaker the water retention capacity. Therefore, the mass percentage of coal gangue in the mixture is controlled at 20-60%, and the mass percentage of gasification slag is controlled at 10-50%.

[0044] Step 2) adding the fluorine-containing mine water into the mixture and stirring to obtain the cemented multi-source coal-based solid waste filling material with predetermined fluidity and bleeding rate.

[0045] In the stirring process, a part of the fluorine-containing mine water is gradually added into the mixture obtained in step 1) using a JJ-15 type cement mortar stirrer, and the stirring is continued, and finally all the fluorine-containing mine water is added, and the stirring is continued until the mixture is uniform.

[0046] The fluorine-containing mine water is the underground gushing water produced in the process of coal mining, and the fluorine ion concentration is 2-10 mg / L.

[0047] In the process of preparing the multi-source coal-based solid waste filling material, the fluorine-containing mine water is introduced, the component characteristics of the multi-source coal-based solid waste can be utilized, and the fluorine ions in the fluorine-containing mine water can be efficiently fixed through physical and chemical reactions in the condensation and hardening process of the filling body, and meanwhile, the strength and environmental safety of the filling body can be considered.

[0048] Water as a liquid medium directly fills the gap between material particles and provides lubrication. The higher the water-cement ratio, the larger the volume proportion of liquid phase, the smaller the friction between particles, and the flowability is significantly improved. However, excessive water will lead to a decrease in the cohesiveness of the slurry, and even segregation may occur.

[0049] Therefore, in order to control the flowability and bleeding rate of the prepared multi-source coal-based solid waste filling material within a predetermined range, the amount of fluorine-containing mine water added is 15-20% of the mass of the mixture.

[0050] In order to ensure that the prepared multi-source coal-based solid waste filling material is smoothly transported, densely filled, and avoids segregation in the filling construction to ensure structural uniformity and mechanical properties, and also to reduce manual intervention and shorten the construction period to optimize the cost, the flowability of the prepared cemented multi-source coal-based solid waste filling material is controlled to be 150-300mm through testing.

[0051] At the same time, in order to improve the strength and durability of the filling body obtained after the filling and solidification of the cemented multi-source coal-based solid waste filling material, reduce the risk of subsidence in the later period, and avoid safety problems such as pollutant migration and void hidden dangers, the bleeding rate of the prepared cemented multi-source coal-based solid waste filling material is controlled to be 2-13% through testing.

[0052] In the process of preparing the multi-source coal-based solid waste filling material, the fluorine-containing mine water is introduced, the component characteristics of the multi-source coal-based solid waste can be utilized, and the fluorine ions in the fluorine-containing mine water can be efficiently fixed through physical and chemical reactions in the condensation and hardening process of the filling body, and meanwhile, the strength and environmental safety of the filling body can be considered.

[0053] In the process of preparing the multi-source coal-based solid waste filling material, the fluorine-containing mine water is introduced, the component characteristics of the multi-source coal-based solid waste can be utilized, and the fluorine ions in the fluorine-containing mine water can be efficiently fixed through physical and chemical reactions in the condensation and hardening process of the filling body, and meanwhile, the strength and environmental safety of the filling body can be considered.

[0054] The application provides a preparation method of a multi-source coal-based solid waste filling material, which can effectively fill goaf generated in coal mining by fully utilizing solid wastes in various coal industries, so that the industrial solid waste resources can be fully recycled and utilized, the problems of land resource occupation and environmental influence caused by the large amount of solid waste stacking can be solved, and the comprehensive recycling and utilization of waste resources is achieved, and green environmental protection is achieved.

[0055] The application further provides application of the multi-source coal-based solid waste filling material, and the prepared cemented multi-source coal-based solid waste filling material is used for filling goaf in coal mining, and the method specifically comprises the following steps.

[0056] In step 1), the prepared cemented multi-source coal-based solid waste filling material is delivered and filled into the goaf in the process of coal mining. Since the fluidity and water bleeding rate of the cemented multi-source coal-based solid waste filling material prepared in the application are controlled within a certain range, the cemented multi-source coal-based solid waste filling material has good fluidity and can be directly delivered to the goaf in the coal mine by a pump through a pipeline, so that the goaf is filled.

[0057] In step 2), the cemented multi-source coal-based solid waste filling material filled into the goaf in the coal mine is cured for 3-28 days at normal temperature and pressure.

[0058] In order to conveniently understand the compressive performance of the multi-source coal-based solid waste filling material after curing, the multi-source coal-based solid waste filling material is poured into a mold, and the compressive strength test is performed under standard conditions for 3, 7 and 28 days, so as to evaluate the mechanical performance of the filling material.

[0059] In the formula, the size of the mold is 70.7mm*70.7mm*70.7mm, and the mold is demolded after curing for 24 hours.

[0060] In the formula, the curing box for curing is a Cangzhou Huaxi YH-90B type, the standard condition is that the temperature is (20±3) DEG C, the humidity is higher than 95%, and the specified time is 3, 7 and 28 days.

[0061] In the formula, the compressive strength is tested according to GB / T 50081-2002 “Standard for Testing Methods of Mechanical Properties of Ordinary Concrete”. Specifically, a 0.5mm min –1 Constant displacement rate is used for loading test, and the stress and displacement performance are recorded once every 1s until the sample is damaged. For each curing time, the compressive strength test is performed three times to obtain an average value.

[0062] The cemented multi-source coal-based solid waste filling material has a compressive strength of 0.8-2.5 MPa after curing for 3 days at normal temperature and pressure. The cemented multi-source coal-based solid waste filling material has a compressive strength of 1.8-3.5 MPa after curing for 7 days at normal temperature and pressure. The cemented multi-source coal-based solid waste filling material has a compressive strength of 2.5-14.0 MPa after curing for 28 days at normal temperature and pressure.

[0063] The cemented multi-source coal-based solid waste filling material filled into the coal mine goaf has different curing times at normal temperature and pressure, and the filling body obtained after curing has different compressive strengths due to different physical and chemical changes in the material: in the early stage (1-7 days), the hydration reaction generates calcium silicate hydrate, calcium hydroxide and other products, at this time the crystal structure is not completely formed, the internal pore is more, and the strength grows fast; in the middle stage (7-28 days), the hydration product fills the pore, the crystal structure tends to be dense, and the strength continues to increase, in the later stage (more than 28 days), the hydration reaction is close to completion, the strength grows slowly and tends to be stable. In addition, factors such as material composition and formula (such as type of cementing material, water-binder ratio, and aggregate characteristics), curing conditions (temperature, humidity, and curing environment), and thermodynamic limitations of chemical reaction also affect the strength difference at different ages. Microstructurally, short age is mainly a porous network structure, which is prone to stress concentration, and long age is a dense crystal-gel composite, which has enhanced compressive strength. This law is of great significance in engineering, as fast-hardening materials are required for early strength demand scenarios, long-term stability scenarios require attention to late-stage strength growth, quality acceptance is often based on 28-day strength, and special projects require longer age data.

[0064] Therefore, as a specific embodiment of the present application, the cemented multi-source coal-based solid waste filling material has a compressive strength of the filling body obtained after curing of 2.5-14.0 MPa after curing for 28 days at normal temperature and pressure, which is best in practical application and can fully meet the mechanical strength requirements of the coal mine goaf.

[0065] The cured multi-source coal-based solid waste filling material can fix fluorine ions in the fluorine-containing mine water and reduce the fluorine ion concentration in the leaching solution.

[0066] The cemented multi-source coal-based solid waste filling material filled into the coal mine goaf not only has a physical and chemical reaction with the fluorine ions in the fluorine-containing mine water added during preparation to achieve efficient fixation of fluorine ions during condensation and hardening, but also continuously interacts with the fluorine ions in a large amount of underground gushing water generated during coal mining in the goaf, which can further fix the fluorine ions in the underground gushing water in the goaf, thereby greatly reducing the fluorine ion concentration in the mine water seeping (i.e., the leaching solution) from the cured multi-source coal-based solid waste filling material, and reaching the national comprehensive wastewater discharge standard.

[0067] The prepared multi-source coal-based solid waste filling material contacts fluorine ions in the fluorine-containing mine water, and the cement, fly ash, bottom slag and desulfurization gypsum in the filling material can effectively fix the fluorine ions in the mine water. Among them, the cement and the desulfurization gypsum provide Ca 2 + and F- generate a difficultly soluble CaF precipitate, the Al 3 + in the cement and the Al-containing materials such as fly ash and bottom slag release Al

[0068] In order to verify the fixing effect of the multi-source coal-based solid waste filling material after curing on the fluorine ions in the fluorine-containing mine water, a proper amount of the multi-source coal-based solid waste filling material after curing for 28 days is crushed for fluorine ion leaching test, and then the fluorine ion concentration in the leaching solution is tested. The fluorine ion concentration in the leaching solution after the fluorine ions in the mine water are fixed by the multi-source coal-based solid waste filling material is ≤1 mg / L, which meets the national comprehensive wastewater discharge standard.

[0069] Among them, the fluorine ion leaching test adopts the national environmental protection standard HJ 557-2010 “Solid waste-leaching toxicity extraction procedure-horizontal oscillation method”. Specifically, the following steps are included:

[0070] Firstly, the multi-source coal-based solid waste filling material sample after curing for 28 days is crushed to obtain a solid powder sample.

[0071] Then, a fluorine-containing solution with a fluorine ion concentration of 2-10 mg / L is prepared by using a fluorine salt with a purity of 99.99% to simulate the fluorine-containing mine water.

[0072] Finally, the powder sample is passed through a sieve with a hole diameter of 3 mm, and the powder sample with a weight of 100 g is weighed and placed in a 2L extraction bottle. The prepared fluorine-containing solution is added according to the liquid-solid ratio of 10:1. The bottle is fixed on a horizontal oscillator, and the oscillation frequency is 110±10 / min and the amplitude is 40 mm. After oscillation at room temperature for 8h, it is statically placed for 16h, and the liquid is detected by 0.45μm microporous filter membrane. The fluorine ion content in the leaching solution is below 1 mg / L, so it can be judged that the multi-source coal-based solid waste filling material after curing for 28 days has good fluorine fixation capacity.

[0073] Therefore, the prepared multi-source coal-based solid waste filling material is filled into a goaf generated by coal mining, and the solidified multi-source coal-based solid waste filling material obtained after curing of the multi-source coal-based solid waste filling material has not only the compressive strength meeting the use requirement of the goaf on the mechanical property of the filling material, but also effectively reacts and fixes the fluorine ions in the mine water, so that the fluorine ions in the leaching solution are greatly reduced and can fully meet the sewage discharge standard.

[0074] The preparation method and application of the multi-source coal-based solid waste filling material are specifically described below through examples.

[0075] Example 1

[0076] A preparation method of a multi-source coal-based solid waste filling material comprises the following components with the mass percentage (accounting for the total mass of solids): P.I 42.5 Portland cement 4%, fly ash 13%, furnace bottom slag 5%, desulfurization gypsum 3%, coal gangue 60%, gasification slag 15%, fluorine ion solution 15.5%, and powder polycarboxylic acid high-efficiency water reducing agent 0.04%.

[0077] In the examples of the present application, the substances are all commercially available goods well known to those skilled in the art without special instructions.

[0078] In the examples of the present application, the fly ash is preferably fly ash. The chemical composition of the fly ash is not specially limited in the examples of the present application, and the chemical composition of the fly ash known to those skilled in the art can be used. In the examples of the present application, the Al2O3 and SiO2 of the fly ash account for 80.5% of the total amount, the content of Fe2O3 and CaO is more than 2%, the loss on ignition is 0.19%, the carbon content is low, and the content of other components such as Na2O and MgO is less than 2%. In the examples of the present application, the source of the fly ash is preferably Ningxia Yuanyanghu Power Plant.

[0079] In the examples of the present application, the furnace bottom slag is preferably furnace bottom slag. The chemical composition of the furnace bottom slag is not specially limited in the examples of the present application, and the chemical composition of the furnace bottom slag known to those skilled in the art can be used. In the examples of the present application, the Al2O3 and SiO2 of the furnace bottom slag account for 83.08% of the total amount, the content of Fe2O3 and CaO is more than 3%, the loss on ignition is 1.09%, and the content of other components such as Na2O and MgO is less than 2%. In the examples of the present application, the source of the furnace bottom slag is preferably Ningxia Yuanyanghu Power Plant.

[0080] In the embodiment of the present application, the desulfurization gypsum is preferably desulfurization gypsum. The chemical composition of the desulfurization gypsum is not particularly limited in the embodiment of the present application, and the chemical composition of the desulfurization gypsum known to those skilled in the art can be used. In the embodiment of the present application, the SO3 content of the desulfurization gypsum is more than 40%, the CaO content is 28.77%, the SiO2 and MgO contents are both more than 2%, and the loss on ignition is 24.50%. The contents of other components such as Al2O3, Na2O and Fe2O3 are all less than 1%. In the embodiment of the present application, the desulfurization gypsum is preferably obtained from Ningxia Yuanyanghu Power Plant.

[0081] In the embodiment of the present application, the coal gangue is preferably coal gangue. The chemical composition of the coal gangue is not particularly limited in the embodiment of the present application, and the chemical composition of the coal gangue known to those skilled in the art can be used. In the embodiment of the present application, the Al2O3 and SiO2 contents of the coal gangue are 72.49% of the total amount, the CaO content is 0.10%, the Fe2O3 content is 9.44%, the loss on ignition is 14.03%, and the contents of other components such as Na2O and MgO are all less than 2%. The coal gangue is crushed by an e-type crusher to form gangue particles with a maximum particle size of less than 4.75 mm, and the fineness modulus is 2.83. In the embodiment of the present application, the coal gangue is preferably obtained from Ningxia Renjiazhuang Coal Mine.

[0082] In the embodiment of the present application, the gasification slag is preferably gasification coarse slag. The chemical composition of the gasification slag is not particularly limited in the embodiment of the present application, and the chemical composition of the gasification slag known to those skilled in the art can be used. In the embodiment of the present application, the Al2O3, SiO2 and CaO contents of the gasification slag are 73.39% of the total amount, the Fe2O3 content is 8.84%, the loss on ignition is 10.30%, and the contents of other components such as Na2O and MgO are all less than 2%. The fineness modulus of the gasification slag is 1.73, and the particles with a particle size of 0.15-0.6 mm account for 75%, which belongs to fine sand. In the embodiment of the present application, the gasification slag is preferably obtained from Ningxia Renjiazhuang Coal Mine.

[0083] In the embodiment of the present application, the fluoride ion solution is prepared by using sodium fluoride with a purity of 99.99%, and the fluoride ion concentration is 5 mg / L.

[0084] In the embodiment of the present application, the powder polycarboxylate superplasticizer is produced by Shanghai Chenqi Chemical Technology Co., Ltd., and the brand is Sika, and the model is 540P.

[0085] The silicate cement, fly ash, bottom slag and desulfurization gypsum are collectively referred to as cementitious materials, and the gasification slag and coal gangue are collectively referred to as aggregates.

[0086] The preparation method comprises the following steps: stirring the above-mentioned cementitious material, aggregate, and powdered polycarboxylic acid high-efficiency water-reducing agent in a cement mortar mixer according to the above-mentioned mass percentage for 1 minute, then continuously mixing and stirring with the fluoride ion solution according to the above-mentioned mass percentage for 2 minutes, then standing for 1 minute, mixing for another 2 minutes, and finally sampling.

[0087] Detect the performance of the filling material: the fluidity test is in accordance with ASTM D6103-04. Specifically: a cylinder with a diameter of 75mm and a height of 150mm is used as a fluidity measuring instrument to measure the diameter of the filling material after it flows; the water bleeding rate test is carried out in accordance with GB / T 50080-2002 "Standard test method for performance of ordinary concrete mixtures". Specifically: Pour the CLSM into a 1L capacity cylinder and cover it with a layer of plastic wrap to ensure that the discharged water does not evaporate. Measure the discharged water content of the mixture every 15 minutes in the first hour and the following hour until the amount of discharged water no longer changes; the compressive strength is tested in accordance with GB / T 50081-2002 "Standard test method for mechanical properties of ordinary concrete". Specifically: use 0.5mm min –1 The samples were loaded at a constant displacement rate, with stress and displacement recorded every 1 second until failure. For each curing time, the compressive strength test was performed three times and the average value was obtained.

[0088] The fluidity, water bleeding rate, and 3-, 7-, and 28-day compressive strength of the multi-source coal-based solid waste filling material prepared in the embodiment of the present invention are shown in Table 3:

[0089] Table 3

[0090]

[0091] To test the filler's ability to solidify fluoride ions, the fluoride ion leaching test was conducted according to China's national environmental protection standard HJ557-2010, "Solid Waste - Leaching Toxicity Extraction Procedure - Horizontal Oscillation Method." Specifically, all sample particles were passed through a 3mm sieve. A 100g sample was weighed and placed in a 2L extraction bottle. Deionized water was added at a liquid-to-solid ratio of 10:1. The bottle was mounted on a horizontal oscillator with an oscillation frequency of 110±10 / min and an amplitude of 40mm. After oscillation at room temperature for 8 hours, the sample was allowed to rest for 16 hours. The liquid was then filtered through a 0.45μm microporous membrane for testing.

[0092] The average value of the fluoride ion leachate data of the embodiment of the present invention is 0.85 mg / L, which satisfies

[0093] "GB3838-2002 Surface Water Environmental Quality Standard" Class III standard.

[0094] Example 2

[0095] A preparation method of a multi-source coal-based solid waste filling material, comprising the following components in percentage by mass (accounting for the total mass of solids): P.I 42.5 Portland cement 6%, fly ash 11%, bottom slag 5%, desulfurization gypsum 3%, coal gangue 60%, gasification slag 15%, fluoride ion solution 15.5%, and powder polycarboxylic acid superplasticizer 0.06%.

[0096] Among them, the Portland cement, fly ash, bottom slag, desulfurization gypsum, coal gangue, gasification slag and powder polycarboxylic acid superplasticizer are the same as in Example 1.

[0097] The fluoride ion concentration is 6 mg / L, and the proportion of the fluoride ion solution in the total mass of solids is the same as in Example 1.

[0098] The preparation method of the filling material is the same as in Example 1.

[0099] The performance detection of the filling material is the same as in Example 1.

[0100] The fluidity, bleeding rate, 3, 7 and 28-day compressive strength of the multi-source coal-based solid waste filling material prepared in the embodiment of the present application are as shown in Table 4:

[0101] Table 4

[0102]

[0103] The detection method of the solidification effect of the filling material on fluoride ions in the embodiment of the present application is the same as in Example 1.

[0104] The average value of the fluoride ion leaching solution data in the embodiment of the present application is 0.89 mg / L, which meets the requirement of

[0105] The surface water environmental quality standard GB3838-2002 is a class III standard.

[0106] The preparation method and application of the multi-source coal-based solid waste filling material provided by the present application prepare a green filling material meeting the requirements of mines, improve the comprehensive utilization level of coal-based solid waste, promote the application of coal-based solid waste in the field of mine filling, and effectively solidify the fluoride ions in the fluoride-containing mine water, eliminating fluoride pollution.

[0107] Finally, it should be noted that the above specific embodiments are only used to illustrate the technical solutions of the present application and are not limiting, and although the present application has been described in detail with reference to examples, those skilled in the art should understand that the technical solutions of the present application can be modified or replaced equivalently without departing from the spirit and scope of the present application, and they should be covered in the scope of the claims of the present application.

Claims

1. A method for preparing multi-source coal-based solid waste filling materials, characterized in that: The steps include: Cement, fly ash, bottom ash, desulfurized gypsum, coal gangue, gasified slag and water reducing agent are mixed and stirred to obtain a mixed material; Fluorine-containing mine water is added to the mixed material and stirred to obtain a cemented multi-source coal-based solid waste filling material with predetermined fluidity and water bleeding rate.

2. The method for preparing a multi-source coal-based solid waste filling material according to claim 1, characterized in that: Calculated by mass percentage, the mixture comprises 5-8% cement, 10-20% fly ash, 4-10% bottom slag, 6-10% desulfurized gypsum, 20-60% coal gangue, 10-50% gasified slag, and 0.02-0.10% water reducer.

3. The method for preparing a multi-source coal-based solid waste filling material according to claim 2, characterized in that: The cement is PI 42.5 silicate cement; the water reducer includes one or more of sulfate water reducer, polycarboxylic acid water reducer, fatty acid water reducer, and phosphate water reducer.

4. The method for preparing a multi-source coal-based solid waste filling material according to claim 1, characterized in that: The agitators used for mixing the cement, fly ash, bottom ash, desulfurized gypsum, coal gangue, gasified slag and water reducer and for adding fluorine-containing mine water into the mixture are all JJ-15 cement mortar mixers.

5. The method for preparing a multi-source coal-based solid waste filling material according to claim 1, characterized in that: The amount of the fluorine-containing mine water added is 15-20% of the mass of the mixed material.

6. The method for preparing a multi-source coal-based solid waste filling material according to claim 5, characterized in that: The fluoride ion concentration in the fluoride-containing mine water is 2-10 mg / L.

7. The method for preparing a multi-source coal-based solid waste filling material according to claim 1, characterized in that: The fluidity of the cemented multi-source coal-based solid waste filling material is 150-300 mm, and the water bleeding rate of the cemented multi-source coal-based solid waste filling material is 2-13%.

8. An application of the multi-source coal-based solid waste filling material according to claims 1-7, characterized in that: The multi-source coal-based solid waste filling material is used to fill the goaf of coal mining, and includes: During the coal mining process, cemented multi-source coal-based solid waste filling materials are transported and filled into the goaf; The cemented multi-source coal-based solid waste filling material is cured at room temperature and pressure for 3-28 days before solidification; The solidified multi-source coal-based solid waste filling material fixes the fluoride ions in the mine water and reduces the fluoride ion concentration in the leachate.

9. The use of the multi-source coal-based solid waste filling material according to claim 8, characterized in that: The compressive strength of the cemented multi-source coal-based solid waste filling material after curing at room temperature and pressure for 3 days is 0.8-2.5 MPa, the compressive strength of the cemented multi-source coal-based solid waste filling material after curing at room temperature and pressure for 7 days is 1.8-3.5 MPa, and the compressive strength of the cemented multi-source coal-based solid waste filling material after curing at room temperature and pressure for 28 days is 2.5-14.0 MPa.

10. The use of the multi-source coal-based solid waste filling material according to claim 8, characterized in that: After the fluoride ions in the mine water are fixed by the multi-source coal-based solid waste filling material, the fluoride ion concentration in the leachate is ≤1 mg / L.

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