Method for preparing active cementing material from calcium-based solid waste and coal gangue

Abstract

The invention discloses a method for preparing an active cementing material from calcium-based solid waste and coal gangue, which comprises the following steps: S1, respectively crushing coal gangue, calcium-based solid waste and fuel to obtain crushed coal gangue, calcium-based solid waste and fuel; s2, the coal gangue obtained in the step S1, the calcium-based solid waste and fuel are blended according to a blending scheme, water is added, the materials are mixed to be uniform, and a mixture is obtained; s3, granulating the mixture to obtain raw material granules; s4, firstly paving a backing material on a trolley of a belt type sintering machine, then distributing the raw material particles, then performing ignition, heat preservation, air draft sintering and cooling, and performing decarburization and activation on the coal gangue to obtain finished ore; and S5, the finished ore is subjected to crushing and fine grinding treatment, and the active cementing material is obtained. The active cementing material is prepared by using calcium-based solid waste and coal gangue, the coal gangue can be used as a substrate of silicon-aluminum in the cementing material, carbon in the coal gangue can also play a role of fuel, the calcium-based solid waste is added to play a role of calcium supplementation, and the fixed carbon content of the mixture is adjusted by adding the calcium-based solid waste.

Description

Technical Field

[0001] The present invention belongs to the technical field of comprehensive utilization of solid waste, and particularly relates to a method for preparing an active cementitious material by synergistically using calcium-based solid waste and coal gangue. Background Art

[0002] As the world's largest coal consumer and producer, China generates a large amount of coal gangue during coal mining and washing processes, and the generation amount accounts for 15% - 20% of the coal production. Coal gangue has become the solid waste with the largest discharge and stockpile in China at present. At the current stage, the number of gangue mountains in state-owned key coal mines exceeds 1500, covering an area of about 15,000 hectares, and the cumulative stockpile has exceeded 7 billion tons, and it is continuously increasing at a rate of 150 - 350 million tons per year.

[0003] A large amount of coal gangue is stacked outdoors, not only occupying precious land resources, but also causing serious pollution to air, water bodies and soil. Therefore, the resource utilization and large-scale consumption of coal gangue have become an urgent matter. At present, the application ways of coal gangue mainly include producing energy, recovering valuable metals, preparing chemical products and preparing building materials, etc. Among them, preparing building materials can realize the high-value and large-scale utilization of coal gangue. However, factors such as residual carbon, organic matter and burning loss in coal gangue will have an adverse impact on the cementing performance, frost resistance and durability of cementitious materials. Therefore, the key to preparing cementitious materials with coal gangue lies in decarbonization and activation, and common activation methods include mechanical activation, chemical activation, thermal activation and microwave activation.

[0004] In terms of related processes, Chinese Patent CN117534358B discloses a coal gangue fuel-free self-heating sintering decarbonization process, in which coal gangue is calcined in a vertical kiln for 3 - 4 hours. Although the process is simple, it has problems such as long calcination time, high energy consumption and low output. The coal gangue microwave activation preparation geopolymer material and its method disclosed in Chinese Patent CN113429137B need to blow coal gangue powder into a microwave processor with air flow, heat it up to 600 - 800 °C and then keep it warm for 1 - 6 hours. This process also has problems such as long calcination time, high energy consumption and low output, and it is extremely difficult to make microwave ovens large-scale and industrialize, with high costs. Therefore, both of these two processes cannot handle a huge amount of coal gangue on a large scale.

[0005] In addition, Chinese patents CN113526894B, CN113429136B, and CN113526895B disclose a method for strengthening the sintering and decarbonization of coal gangue, a coal gangue layered charging sintering decarbonization process, and a method for double-layer oxygen-enriched sintering decarbonization of coal gangue, respectively. These methods all use the sintering process to activate and decarbonize coal gangue to improve its activity. However, these processes require the fixed carbon content of coal gangue to be 2% - 5%, which limits the application of coal gangue with a higher fixed carbon content. Moreover, the raw material is only coal gangue, which easily leads to poor activation effect and further restricts the popularization and application of these processes. Summary of the Invention

[0006] Aiming at the problems of small treatment capacity of coal gangue, narrow range of applicable coal gangue, and poor activation effect of coal gangue in the prior art, the purpose of the present invention is to provide a method for preparing an active cementitious material by using calcium-based solid waste in cooperation with coal gangue. This method can broaden the utilization range of coal gangue, strengthen the activation process of coal gangue by adding calcium-based solid waste, thereby improving the activity of decarbonized coal gangue, and ultimately realizing the high-value and large-scale utilization of calcium-based solid waste and coal gangue.

[0007] To achieve the above technical objectives, the technical solution of the present invention is as follows:

[0008] A method for preparing an active cementitious material by using calcium-based solid waste in cooperation with coal gangue, comprising the following steps:

[0009] S1. Crush coal gangue, calcium-based solid waste, and fuel respectively to obtain crushed coal gangue, calcium-based solid waste, and fuel;

[0010] S2. Mix the coal gangue, calcium-based solid waste, and fuel obtained in step S1 according to the batching scheme, and add water and mix evenly to obtain a mixture;

[0011] S3. Granulate the mixture obtained in step S2 to obtain green pellets;

[0012] S4. First lay a bottom material on the trolley of the belt sintering machine, then charge the green pellets obtained in step S3, and then carry out ignition, heat preservation, suction sintering, and cooling to decarbonize and activate the coal gangue to obtain a finished ore;

[0013] S5. Crush and finely grind the finished ore obtained in step S4 to obtain an active cementitious material.

[0014] Preferably, in step S1, the coal gangue is argillaceous rock gangue, and the fixed carbon content of the coal gangue is 2% - 20%; it is applicable to coal gangue with a fixed carbon content greater than 5%, broadening the utilization range of coal gangue.

[0015] Preferably, in step S1, the main chemical component of the calcium-based solid waste is calcium oxide, including but not limited to one or more of steel slag, carbide slag, paper mill white mud, sewage treatment plant sludge, blast furnace slag, desulfurized gypsum, waste marble, calcium-based dust collection powder, sugar filter residue, alkali residue, and calcium-based biomass solid waste.

[0016] The calcium-based solid waste decomposes at high temperature to produce active free calcium oxide, which reacts with silicate minerals and iron-containing minerals in the coal gangue to form minerals such as tricalcium silicate (C3S), dicalcium silicate (C2S), tricalcium aluminate (C3A), and tetracalcium ferroaluminate (C4AF). These generated minerals have hydraulicity and are important components of active cementitious materials.

[0017] More preferably, the calcium-based biomass solid waste includes one or more of eggshells, shells, and fish bones.

[0018] Preferably, in step S1, the fuel is one or more of anthracite, bituminous coal, and semi-coke.

[0019] Preferably, in step S1, the coal gangue, calcium-based solid waste, and fuel are crushed to a particle size of -8 mm, and the crushing is carried out using one or more of a jaw crusher, a pair-roll crusher, a cone crusher, a counterattack crusher, an impact crusher, and a hammer crusher.

[0020] If the particles after crushing are too coarse, the downward movement speed of the combustion zone will be too fast, the high-temperature holding time will be short, and it will be difficult to burn through the inside of the particles, resulting in a high residual carbon content and insufficient activation. If the crushed particles are too fine, the pelletizing effect will be poor, resulting in a slow sintering speed, a reduced utilization coefficient, and even "flameout".

[0021] Preferably, in step S2, the mass percentages (by dry weight) of the coal gangue, calcium-based solid waste, and fuel are as follows:

[0022] Coal gangue 50% - 98%, calcium-based solid waste 2% - 50%, fuel 0% - 7%.

[0023] The coal gangue can not only serve as the silicon-aluminum matrix in the cementitious material, but also play the role of fuel during the activation process due to the carbon it contains. The calcium-based solid waste plays two roles: one is to provide free calcium oxide to enhance the activation effect of the coal gangue; the other is to adjust the carbon content of the mixture by adding calcium-based solid waste, so that the fixed carbon content of the mixture remains at 2% - 10%, and the addition ratio is adjusted according to the output and product performance. When the fixed carbon content in the coal gangue is low, fuel needs to be added, and vice versa. If the fixed carbon content in the mixture is too low, it may lead to decarbonization, the material layer cannot burn or burns insufficiently during the activation process, resulting in low activity of the cementitious material. If the fixed carbon content is too high, it is easy to cause the material layer temperature to be too high, and a large amount of mullite phase is easily generated during the crystallization process, resulting in a decrease in the activity of the cementitious material.

[0024] More preferably, the fixed carbon content of the mixture is maintained at 2% - 6.5%.

[0025] Preferably, in step S2, after batching, a high-intensity mixer is used to mix the materials evenly, and the high-intensity mixing time is 2 - 5 min; by using a high-intensity mixer and through high-speed stirring blades and turbulent mixing technology, the materials are quickly mixed in the mixing chamber, shortening the mixing time and improving production efficiency; the high-intensity mixing adopts shear, extrusion and multi-dimensional mixing methods to break the agglomeration of the materials, ensure the uniform distribution of the materials, make the decarbonization and activation reactions more sufficient, and make the performance of the later activated products more stable and consistent.

[0026] Preferably, in step S3, a cylindrical granulator is used for granulation, the rotation speed of the cylindrical granulator is 20 - 40 rpm, and the granulation time is 3 - 7 min; the moisture content of the green pellets obtained by granulation is 6% - 11%, and the particle size is 3 - 10 mm. Only when the moisture content and particle size of the green pellets are appropriate can the appropriate permeability of the material layer be maintained, so as to achieve the full decarbonization and activation of coal gangue.

[0027] Preferably, in step S4, the thickness of the bedding material is controlled to be 15 - 70 mm, and the particle size of the bedding material is 15 - 25 mm.

[0028] If the fixed carbon content of the coal gangue < 5%, the bedding material is the original crushed coal gangue; if the fixed carbon content of the coal gangue ≥ 5%, the bedding material is the crushed finished ore, to prevent the bedding material from being too hot and damaging the grate bars.

[0029] Preferably, in step S4, during the feeding process, the total height of the material layer (the height of the bedding material + the height of the green pellets) is controlled to be 900 - 2000 mm.

[0030] Using an ultra-high material layer for decarbonization and activation can utilize the automatic heat storage effect of the ultra-high material layer to increase the temperature of the combustion zone, making the decarbonization and activation of coal gangue more sufficient. It can be seen that using an ultra-high material layer can not only obtain high-performance cementitious materials, but also reduce energy consumption and carbon emissions. However, the material layer should not be too high, as too high a material layer is likely to lead to poor permeability of the material layer, too large a material layer resistance, too slow a vertical sintering speed, and a decrease in utilization coefficient.

[0031] Preferably, in step S4, the ignition time is 1 - 5 min, the ignition temperature is 950 - 1150 °C, the ignition negative pressure is 4 - 6 kPa, the heat preservation temperature is 800 - 900 °C, and the heat preservation time is 3 - 6 min. If the temperature and time of ignition and heat preservation are too low, the material layer may not be ignited; if too high, it will waste natural gas and electric energy.

[0032] Preferably, in step S4, the negative pressure during suction sintering is 9-18 kPa. If the suction negative pressure is too low, the vertical sintering speed will decrease and the utilization coefficient will decrease; if the suction negative pressure is too high, the burden on the suction fan will increase, the power consumption will increase, and after the vertical sintering speed increases, it is easy to cause insufficient decarburization of the finished ore and low activity.

[0033] Preferably, in step S4, the cooling time is 5-10 min and the cooling negative pressure is 5-15 kPa. The cooling time and cooling negative pressure have an important impact on the activity of the cementitious material. Cooling is not simply a reduction in temperature, but is accompanied by a series of physical and chemical changes, and two processes of liquid phase solidification and phase change are carried out simultaneously. Adopting rapid cooling can improve the quality of the product and make it have grindability; at the same time, waste heat recovery can be carried out during the cooling process.

[0034] Preferably, in step S5, the finished ore is crushed and finely ground to obtain an active cementitious material. The properties of the active cementitious material are as follows: the proportion of particles with a size of -0.08 mm is 97%-99%, the loss on ignition is ≤3%, the residual carbon content is ≤3%, the specific surface area is 300-400 m 2 / kg, and the activity index is ≥70%.

[0035] Compared with the prior art, the beneficial technical effects of the present invention are:

[0036] (1) The fixed carbon content of the coal gangue adopted in the present invention is 2%-20%. Compared with the fixed carbon content of the coal gangue required by the prior art (2%-5%), the present invention greatly broadens the range of available coal gangue. The source of calcium-based solid waste is wide and the production volume is large. A variety of industrial waste residues can be used as calcium-based solid waste, making the invention have wide applicability and enabling the high-value utilization of a variety of solid waste.

[0037] (2) The present invention uses calcium-based solid waste to synergistically prepare an active cementitious material with coal gangue. The coal gangue can not only be used as the silicon-aluminum matrix in the cementitious material, but also the carbon in the coal gangue can play the role of fuel. Adding calcium-based solid waste can play the role of "supplementing calcium", and at the same time, the fixed carbon content of the mixture is adjusted by adding calcium-based solid waste. The calcium-based solid waste reacts with the minerals in the coal gangue at high temperature to strengthen the activation effect of the coal gangue and form minerals such as tricalcium silicate (C3S), dicalcium silicate (C2S), tricalcium aluminate (C3A), and tetracalcium ferroaluminate (C4AF). These minerals play an important role in the hydration process, so that an active cementitious material with excellent performance can be prepared.

[0038] (3) The present invention determines the type of bottom paving material according to the fixed carbon content of the coal gangue. When the fixed carbon content of the coal gangue is low, the original coal gangue is used as the bottom paving material, and when the fixed carbon content of the coal gangue is high, the finished ore is used as the bottom paving material. This can not only protect the grate bars, but also realize the efficient utilization of the coal gangue and increase the consumption of the coal gangue.

[0039] (4) The present invention makes full use of the automatic heat storage effect of an ultra-high material layer (900 - 2000 mm) during the sintering process and the fixed carbon in coal gangue, which can reduce the fuel consumption, and even without additional fuel addition, to achieve the decarbonization and activation of coal gangue during sintering. This can not only reduce energy consumption and production costs, but also contribute to the full decarbonization and activation of coal gangue. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the embodiments. Obviously, the drawings described below are only the embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on the provided drawings.

[0041] Figure 1 It is the process flow chart of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0042] The following will clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present application.

[0043] The following will further describe the present application in detail with reference to the drawings and specific embodiments:

[0044] Embodiment 1

[0045] The coal gangue from a certain area is used, and its chemical composition is as follows: SiO2 67.30%, Al2O3 12.09%, CaO 2.76%, MgO 1.41%, fixed carbon 3.18%, LOI (loss on ignition) 8.08%.

[0046] The chemical composition of steel slag is as follows: SiO2 17.52%, Al2O3 2.98%, CaO 34.77%, MgO 7.99%, LOI (loss on ignition) -1.06%.

[0047] The raw coal gangue and steel slag are crushed to -8 mm using a jaw crusher.

[0048] Mixing is carried out according to 90% coal gangue and 10% steel slag, adding water and feeding it into a high-strength mixer for 3 minutes, and then feeding it into a cylindrical granulator for granulation. The granulation time is 5 minutes. The moisture content of the prepared green material is 8.5%, the particle size of the green material is 3 - 10 mm, and the air permeability resistance of the green material is 51 mmH2O.

[0049] The belt-type sintering machine (with a material layer height of 900 mm) feeds materials through rollers, uses raw coal gangue with a particle size of 15 - 25 mm as the bedding material, the thickness of the bedding material is 50 mm, then feeds the green material, the ignition temperature is 1150 °C, the ignition time is 4 min, the ignition negative pressure is 6 kPa. After ignition, heat preservation is carried out, heat preservation is carried out at 900 °C for 5 min, the sintering negative pressure is 9 kPa. After sintering, the exhaust negative pressure is adjusted to 11 kPa. After cooling for 5 min, the decarbonized coal gangue is unloaded and naturally cooled in the air. The sintering utilization coefficient is 1.52 t / (m 2 ·h).

[0050] After the decarbonized coal gangue is crushed to -1 mm by a jaw crusher, it is then dry-ground in a ball mill to a specific surface area of 450 m 2 / kg, the proportion of particles with a size of -0.08 mm is 98%, then the coal gangue-based cementitious material can be obtained, with a loss on ignition of 1.56%, a residual carbon content of 0.61%, and an activity index of 95.40%.

[0051] Example 2

[0052] Coal gangue from a certain area is used, and its chemical composition is as follows: SiO2 55.78%, Al2O3 20.86%, CaO 0.56%, MgO 0.65%, fixed carbon 3.53%, LOI (loss on ignition) 13.23%.

[0053] The chemical composition of desulfurized gypsum is as follows: SiO2 0.73%, Al2O3 0.32%, CaO 36.11%, MgO 1.56%, LOI (loss on ignition) 11.79%.

[0054] A jaw crusher is used to crush the raw coal gangue and desulfurized gypsum to -8 mm.

[0055] Mixing is carried out according to 90% coal gangue and 10% desulfurized gypsum, adding water and feeding it into a high-strength mixer for mixing for 4 min, then feeding it into a cylindrical granulator for granulation, the granulation time is 7 min, the moisture content of the obtained green material is 8.5%, the particle size of the green material is 3 - 10 mm, and the air permeability resistance of the green material is 49 mmH2O.

[0056] The belt-type sintering machine (with a material layer height of 2000 mm) feeds materials through rollers, uses raw coal gangue with a particle size of 15 - 25 mm as the bedding material, the thickness of the bedding material is 50 mm, then feeds the green material, the ignition temperature is 1150 °C, the ignition time is 5 min, the ignition negative pressure is 6 kPa. After ignition, heat preservation is carried out, heat preservation is carried out at 900 °C for 6 min, the sintering negative pressure is 11 kPa. After sintering, the exhaust negative pressure is adjusted to 15 kPa. After cooling for 8 min, the decarbonized coal gangue is unloaded and naturally cooled in the air. The sintering utilization coefficient is 1.36 t / (m 2 ·h).

[0057] The decarbonized coal gangue is crushed to -1mm by a jaw crusher and then dry-ground in a ball mill to a specific surface area of ​​450m 2 / kg, -0.08mm particles account for 98%, and coal gangue-based cementitious materials can be obtained, with a loss on ignition of 1.03%, a residual carbon content of 0.41%, and an activity index of 85.06%.

[0058] Example 3

[0059] The coal gangue from a certain area was used, and its chemical composition was as follows: SiO2 38.70%, Al2O3 13.11%, CaO 5.45%, MgO 0.92%, fixed carbon 7.30%, and LOI (loss on ignition) 23.55%.

[0060] The chemical composition of sewage treatment plant sludge is as follows: SiO2 0.70%, Al2O3 0.36%, CaO 42.78%, MgO 6.70%, LOI (loss on ignition) 42.41%.

[0061] The sludge is dried and the coal gangue ore and sludge are crushed to -8mm using a jaw crusher.

[0062] The raw material is prepared with 90% coal gangue and 10% sludge, and water is added and the mixture is sent to a high-power mixer for mixing for 5 minutes. The mixture is then sent to a drum granulator for granulation for 6 minutes. The moisture content of the raw material is 8.5%, the particle size is 3-10 mm, and the air permeability resistance is 43 mmH2O.

[0063] The belt sintering machine (material layer height 1000mm) uses rollers to spread the material, using 15-25mm decarbonized coal gangue as the base material, the base material thickness is 70mm, and then the raw material is spread. The ignition temperature is 1150℃, the ignition time is 2min, the ignition negative pressure is 6kPa, and the ignition is completed. Keep warm at 900℃ for 2.5min, the sintering negative pressure is 9kPa, and the exhaust negative pressure is adjusted to 13kPa after sintering. After cooling for 7min, the decarbonized coal gangue is discharged and cooled naturally in the air. The sintering utilization coefficient is 0.94t / (m 2 h).

[0064] The decarbonized coal gangue is crushed to -1mm by a jaw crusher and then dry-ground in a ball mill to a specific surface area of ​​450m 2 / kg, -0.08mm particles account for 98%, and coal gangue-based cementitious materials can be obtained, with a loss on ignition of 2.40%, a residual carbon content of 1.47%, and an activity index of 80.72%.

[0065] Example 4

[0066] Using the coal gangue from a certain area, its chemical composition is as follows: SiO2 56.21%, Al2O3 20.38%, CaO 0.48%, MgO 0.70%, fixed carbon 2.13%, LOI (loss on ignition) 12.15%.

[0067] The chemical composition of the steel slag is as follows: SiO2 17.52%, Al2O3 2.98%, CaO 34.77%, MgO 7.99%, LOI (loss on ignition) -1.06%.

[0068] Anthracite is used as the fuel, and the fixed carbon is 81.27%.

[0069] Use a pair-roll crusher to crush the raw coal gangue, steel slag and anthracite to -8 mm.

[0070] Mix according to 88% coal gangue, 10% steel slag and 2% anthracite, add water and send it into a high-strength mixer to mix for 4 min, then send it into a cylindrical granulator for granulation. The granulation time is 5 min. The moisture content of the prepared raw material is 9.0%, the particle size of the raw material is 3 - 10 mm, and the air permeability resistance of the raw material is 50 mmH2O.

[0071] The belt-type sintering machine (the height of the material layer is 900 mm) distributes the material through a roller. Use 15 - 25 mm raw coal gangue as the bottom layer material, and the thickness of the bottom layer material is 50 mm. Then distribute the raw material, the ignition temperature is 1150 °C, the ignition time is 5 min, the ignition negative pressure is 7 kPa. After ignition, keep warm. Keep warm at 900 °C for 4 min, the sintering negative pressure is 10 kPa. After sintering, adjust the exhaust negative pressure to 13 kPa. After cooling for 5 min, unload the decarbonized coal gangue and let it cool naturally in the air. The sintering utilization coefficient is 1.35 t / (m 2 ·h).

[0072] After the decarbonized coal gangue is crushed to -1 mm by a jaw crusher, then dry-grind it in a ball mill to a specific surface area of 450 m 2 / kg, and the proportion of particles with a size of -0.08 mm is 98%, then the coal gangue-based cementitious material can be obtained, with a loss on ignition of 1.48%, a residual carbon content of 0.75%, and an activity index of 90.02%.

[0073] Example 5

[0074] Using the coal gangue from a certain area, its chemical composition is as follows: SiO2 50.29%, Al2O3 22.86%, CaO 0.98%, MgO 0.57%, fixed carbon 6.09%, LOI (loss on ignition) 17.01%.

[0075] The chemical composition of carbide slag is as follows: SiO2 3.02%, Al2O3 0.86%, CaO 67.95%, MgO 0.11%, LOI (loss on ignition) 24.80%.

[0076] Use a pair-roll crusher to crush the raw coal gangue and carbide slag to -8 mm.

[0077] Mix according to 80% coal gangue and 20% carbide slag, add water and send it into a strong mixer to mix for 2 min, then send it into a cylindrical granulator for granulation. The granulation time is 7 min. The moisture content of the prepared raw material is 8.0%, the particle size of the raw material is 3 - 10 mm, and the air permeability resistance of the raw material is 48 mmH2O.

[0078] The belt sintering machine (with a material layer height of 1000 mm) distributes the material through rollers. Use decarbonized coal gangue of 15 - 25 mm as the bottom material, and the thickness of the bottom material is 55 mm. Then distribute the raw material, with an ignition temperature of 1100 °C, an ignition time of 3 min, an ignition negative pressure of 6 kPa. After ignition, keep warm. Keep warm at 900 °C for 4 min, with a sintering negative pressure of 9 kPa. After sintering, adjust the exhaust negative pressure to 15 kPa. After cooling for 5 min, unload the decarbonized coal gangue and let it cool naturally in the air. The sintering utilization coefficient is 1.29 t / (m 2 ·h).

[0079] After the decarbonized coal gangue is crushed to -1 mm by a jaw crusher, then dry grind it in a ball mill to a specific surface area of 450 m 2 / kg, and the proportion of particles smaller than -0.08 mm is 98%. Then the coal gangue-based cementitious material can be obtained, with a loss on ignition of 1.97%, a residual carbon content of 0.85%, and an activity index of 86.41%.

[0080] Example 6

[0081] Use the coal gangue from a certain area, and its chemical composition is as follows: SiO2 55.78%, Al2O3 20.86%, CaO 0.56%, MgO 0.65%, fixed carbon 3.53%, LOI (loss on ignition) 13.23%.

[0082] The chemical composition of the calcium-based dust collection powder is as follows: SiO2 1.09%, Al2O3 0.50%, CaO 62.80%, MgO 0.83%, LOI (loss on ignition) 26.63%.

[0083] Use a pair-roll crusher to crush the raw coal gangue and calcium-based dust collection powder to -8 mm.

[0084] Mix according to 95% coal gangue and 5% calcium-based dust collector powder, add water and send it into a high-strength mixer for mixing for 3.5 min, then send it into a cylindrical granulator for granulation. The granulation time is 5 min. The moisture content of the prepared raw material is 9.0%, the particle size of the raw material is 3 - 10 mm, and the air permeability resistance of the raw material is 47 mmH2O.

[0085] The belt sintering machine (with a material layer height of 950 mm) is fed through rollers. Use 15 - 25 mm of raw coal gangue as the bottom layer material, and the thickness of the bottom layer material is 40 mm. Then, the raw material is fed for ignition at a temperature of 1150 °C, an ignition time of 5 min, an ignition negative pressure of 6 kPa. After ignition, keep warm at 900 °C for 3 min, the sintering negative pressure is 12 kPa. After sintering, the exhaust negative pressure is adjusted to 15 kPa. After cooling for 5 min, the decarbonized coal gangue is unloaded and naturally cooled in the air. The sintering utilization coefficient is 1.31 t / (m 2 ·h).

[0086] After the decarbonized coal gangue is crushed to -1 mm by a jaw crusher, it is then dry-ground in a ball mill to a specific surface area of 450 m 2 / kg, and the proportion of particles with a size of -0.08 mm is 98%. Then, the coal gangue-based cementitious material can be obtained, with a loss on ignition of 1.31%, a residual carbon content of 0.72%, and an activity index of 82.34%.

[0087] Example 7

[0088] Use the coal gangue from a certain area, and its chemical composition is as follows: SiO2 42.41%, Al2O3 14.28%, CaO 2.66%, MgO 0.89%, fixed carbon 12.15%, LOI (loss on ignition) 29.15%.

[0089] The chemical composition of steel slag is as follows: SiO2 17.52%, Al2O3 2.98%, CaO 34.77%, MgO 7.99%, LOI (loss on ignition) -1.06%.

[0090] The chemical composition of the sludge from the sewage treatment plant is as follows: SiO2 0.70%, Al2O3 0.36%, CaO 42.78%, MgO 6.70%, LOI (loss on ignition) 42.41%.

[0091] Use a cone crusher to crush the raw coal gangue, steel slag, and sludge from the sewage treatment plant to -8 mm.

[0092] Mix according to 70% coal gangue, 20% steel slag, and 10% sludge from the sewage treatment plant, add water and send it into a high-strength mixer for mixing for 4 min, then send it into a cylindrical granulator for granulation. The granulation time is 4 min. The moisture content of the prepared raw material is 8.0%, the particle size of the raw material is 3 - 10 mm, and the air permeability resistance of the raw material is 49 mmH2O.

[0093] The belt sintering machine (with a material layer height of 900 mm) feeds the material through rollers, uses decarbonized coal gangue with a size of 15 - 25 mm as the bedding material, and the thickness of the bedding material is 60 mm. Then, the green material is fed. The ignition temperature is 1100 °C, the ignition time is 2 min, the ignition negative pressure is 5 kPa. After ignition, heat preservation is carried out, and heat preservation is carried out at 850 °C for 3 min. The sintering negative pressure is 9 kPa. After sintering, the exhaust negative pressure is adjusted to 10 kPa. After cooling for 7 min, the decarbonized coal gangue is unloaded and naturally cooled in the air. The sintering utilization coefficient is 1.03 t / (m 2 ·h).

[0094] After the decarbonized coal gangue is crushed to -1 mm by a jaw crusher, it is then dry-ground in a ball mill to a specific surface area of 450 m 2 / kg, and the proportion of particles with a size of -0.08 mm is 98%. Then, the coal gangue-based cementitious material can be obtained, with a loss on ignition of 2.21%, a residual carbon content of 1.03%, and an activity index of 83.69%.

[0095] Example 8

[0096] The coal gangue from a certain area is used, and its chemical composition is as follows: SiO2 34.79%, Al2O3 14.70%, CaO 1.83%, MgO 1.12%, fixed carbon 19.03%, LOI (loss on ignition) 9.16%.

[0097] The chemical composition of the steel slag is as follows: SiO2 17.52%, Al2O3 2.98%, CaO 34.77%, MgO 7.99%, LOI (loss on ignition) -1.06%.

[0098] The chemical composition of the carbide slag is as follows: SiO2 3.02%, Al2O3 0.86%, CaO 67.95%, MgO 0.11%, LOI (loss on ignition) 24.80%.

[0099] A jaw crusher and a pair-roll crusher are used to crush the raw coal gangue, steel slag, and carbide slag to -8 mm.

[0100] Mixing is carried out according to 50% coal gangue, 30% steel slag, and 20% carbide slag. Water is added and fed into a high-strength mixer for mixing for 3 min, and then fed into a cylindrical granulator for granulation. The granulation time is 5 min. The moisture content of the obtained green material is 8.0%, the particle size of the green material is 3 - 10 mm, and the air permeability resistance of the green material is 45 mmH2O.

[0101] The belt-type sintering machine (with a material layer height of 900 mm) feeds materials through rollers. 15 - 25 mm decarbonized coal gangue is used as the underlay material, with a thickness of 70 mm. Then, the green material is fed. The ignition temperature is 1100 °C, the ignition time is 1.5 min, the ignition negative pressure is 5 kPa. After ignition, heat preservation is carried out, at 900 °C for 3 min. The sintering negative pressure is 9 kPa. After sintering, the exhaust negative pressure is adjusted to 13 kPa. After cooling for 10 min, the decarbonized coal gangue is unloaded and naturally cooled in the air. The sintering utilization coefficient is 0.95 t / (m 2 ·h).

[0102] After the decarbonized coal gangue is crushed to -1 mm by a jaw crusher, it is then dry-ground in a ball mill to a specific surface area of 450 m 2 / kg, and the proportion of particles smaller than -0.08 mm is 98%. Then the coal gangue-based cementitious material can be obtained, with a loss on ignition of 2.46%, a residual carbon content of 1.51%, and an activity index of 81.44%.

[0103] Comparative Example 1

[0104] Coal gangue from a certain area is used, and its chemical composition is as follows: SiO2 67.30%, Al2O3 12.09%, CaO 2.76%, MgO 1.41%, fixed carbon 3.18%, LOI (loss on ignition) 8.08%.

[0105] The raw coal gangue is crushed to -8 mm by a jaw crusher.

[0106] After the coal gangue particles are mixed with water, they are fed into a cylindrical granulator for granulation. The granulation time is 5 min. The moisture content of the obtained green material is 8.5%, the particle size of the green material is 3 - 10 mm, and the air permeability resistance of the green material is 44 mmH2O.

[0107] The belt-type sintering machine (with a material layer height of 900 mm) feeds materials through rollers. 15 - 25 mm raw coal gangue is used as the underlay material, with a thickness of 50 mm. Then, the green material is fed. The ignition temperature is 1150 °C, the ignition time is 4 min, the ignition negative pressure is 6 kPa. After ignition, heat preservation is carried out, at 900 °C for 5 min. The sintering negative pressure is 9 kPa. After sintering, the exhaust negative pressure is adjusted to 11 kPa. After cooling for 5 min, the decarbonized coal gangue is unloaded and naturally cooled in the air. The sintering utilization coefficient is 1.28 t / (m 2 ·h).

[0108] After the decarbonized coal gangue is crushed to -1 mm by a jaw crusher, it is then dry-ground in a ball mill to a specific surface area of 450 m 2 / kg, and the proportion of particles smaller than -0.08 mm is 98%. Then the coal gangue-based cementitious material can be obtained, with a loss on ignition of 1.64%, a residual carbon content of 0.97%, and an activity index of 78.74%.

[0109] Comparative Example 2

[0110] The coal gangue from a certain area was used, and its chemical composition was as follows: SiO2 55.78%, Al2O3 20.86%, CaO 0.56%, MgO 0.65%, fixed carbon 3.53%, LOI (loss on ignition) 13.23%.

[0111] The chemical composition of desulfurized gypsum was as follows: SiO2 0.73%, Al2O3 0.32%, CaO 36.11%, MgO 1.56%, LOI (loss on ignition) 11.79%.

[0112] The raw coal gangue and desulfurized gypsum were crushed to -8 mm using a jaw crusher.

[0113] The materials were proportioned at 90% coal gangue and 10% desulfurized gypsum, added with water and sent to a high-strength mixer for mixing for 4 min, and then sent to a cylindrical granulator for granulation. The granulation time was 7 min. The moisture content of the green material was 8.5%, the particle size of the green material was 3 - 10 mm, and the air permeability resistance of the green material was 46 mmH2O.

[0114] The belt sintering machine (with a bed height of 2200 mm) was fed by a roller. The original coal gangue of 15 - 25 mm was used as the bedding material, and the bedding material thickness was 50 mm. Then the green material was fed. The ignition temperature was 1150 °C, the ignition time was 5 min, the ignition negative pressure was 6 kPa. After ignition, heat preservation was carried out, and heat preservation was carried out at 900 °C for 6 min. The sintering negative pressure was 11 kPa. After sintering, the exhaust negative pressure was adjusted to 15 kPa. After cooling for 8 min, the decarbonized coal gangue was unloaded and naturally cooled in the air. The sintering utilization coefficient was 1.06 t / (m 2 ·h).

[0115] After the decarbonized coal gangue was crushed to -1 mm by a jaw crusher, it was then dry-ground in a ball mill to a specific surface area of 450 m 2 / kg, and the proportion of particles with a size of -0.08 mm was 98%. Then the coal gangue-based cementitious material could be obtained, with a loss on ignition of 1.34%, a residual carbon content of 1.07%, and an activity index of 78.63%.

[0116] Comparative Example 3

[0117] The coal gangue from a certain area was used, and its chemical composition was as follows: SiO2 38.70%, Al2O3 13.11%, CaO 5.45%, MgO 0.92%, fixed carbon 6.06%, LOI (loss on ignition) 23.55%.

[0118] The raw coal gangue was crushed to -8 mm using a jaw crusher.

[0119] Mix the coal gangue particles with water evenly and send them into a cylindrical granulator for granulation. The granulation time is 5 minutes. The moisture content of the green material obtained is 8.5%, the particle size of the green material is 3 - 10 mm, and the air permeability resistance of the green material is 41 mmH2O.

[0120] The belt sintering machine (with a material layer height of 800 mm) is fed by a roller. Use the original coal gangue with a size of 15 - 25 mm as the bedding material, and the thickness of the bedding material is 50 mm. Then, feed the green material. The ignition temperature is 1150 °C, the ignition time is 2 minutes, the ignition negative pressure is 6 kPa. After ignition, carry out heat preservation. Carry out heat preservation at 900 °C for 2.5 minutes. The sintering negative pressure is 9 kPa. After sintering, adjust the exhaust negative pressure to 11 kPa. After cooling for 5 minutes, unload the decarbonized coal gangue and let it cool naturally in the air. The sintering utilization coefficient is 0.87 t / (m 2 ·h). However, because the fixed carbon content of the coal gangue is > 5%, using the original coal gangue as the bedding material causes the grate bars to burn through.

[0121] After the decarbonized coal gangue is crushed to -1 mm by a jaw crusher, it is then dry-ground in a ball mill to a specific surface area of 450 m 2 / kg, and the proportion of particles with a size of -0.08 mm is 98%, then the coal gangue-based cementitious material can be obtained, with a loss on ignition of 2.50%, a residual carbon content of 2.02%, and an activity index of 78.48%.

[0122] It can be seen from Examples 1 - 8 and Comparative Examples 1 - 3 that adding calcium-based solid waste for sintering decarbonization and activation of coal gangue can improve the sintering utilization coefficient, and the decarbonization and activation of coal gangue are more sufficient. The residual carbon content and loss on ignition of the cementitious material are reduced, and the activity index is significantly improved. And this technology is applicable to coal gangue with a fixed carbon content of 2% - 20%. In Comparative Example 2, the material layer height is too high, resulting in a decrease in the utilization coefficient and product activity; in Comparative Example 3, because the original coal gangue with too high a fixed carbon content is used as the bedding material, the grate bars are damaged.

[0123] The above content is only a specific implementation case of this application, rather than all application cases of this application. All solutions that follow the technical idea of this application and those that make changes to the technical idea of this application are within the protection scope of the claims of this application.

Claims

1. A method for preparing active cementitious materials by using calcium-based solid waste and coal gangue, characterized in that: It includes the following steps: S1. Crush gangue, calcium-based solid waste, and fuel respectively to obtain crushed gangue, calcium-based solid waste, and fuel. S2. Mix the gangue, calcium-based solid waste, and fuel obtained in step S1 according to the batching plan, and add water and mix evenly to obtain a mixture. S3. Pelletize the mixture obtained in step S2 to obtain green pellet particles. S4. First, lay a bottom layer on the pallet of the belt sintering machine, then distribute the green pellet particles obtained in step S3, and then carry out ignition, heat preservation, suction sintering, and cooling to decarbonize and activate the gangue to obtain finished ore. S5. Crush and finely grind the finished ore obtained in step S4 to obtain an active cementitious material.

2. The method for preparing an active cementitious material by using calcium-based solid waste to synergistically treat coal gangue according to claim 1, wherein, In step S1, the gangue is argillaceous rock gangue, and the fixed carbon content of the gangue is 2% - 20%. The main chemical component of the calcium-based solid waste is calcium oxide, including but not limited to one or more of steel slag, carbide slag, paper mill white mud, sewage treatment plant sludge, blast furnace slag, desulfurized gypsum, waste marble, calcium-based dust collector powder, sugar filter residue, alkali residue, and calcium-based biomass solid waste. The fuel is one or more of anthracite, bituminous coal, and semi-coke.

3. The method for preparing an active cementitious material by using calcium-based solid waste to synergistically treat coal gangue according to claim 1, characterized in that, In step S1, crush the gangue, calcium-based solid waste, and fuel to a particle size of -8 mm, and the crushing is carried out by one or more of a jaw crusher, a pair of roll crushers, a cone crusher, a counterattack crusher, an impact crusher, and a hammer crusher.

4. The method for preparing an active cementitious material by using calcium-based solid waste to synergistically treat coal gangue according to claim 1, characterized in that, In step S2, the mass percentages (by dry weight) of the gangue, calcium-based solid waste, and fuel are: Gangue 50% - 98%, calcium-based solid waste 2% - 50%, fuel 0% - 7%.

5. The method for preparing an active cementitious material by using calcium-based solid waste to synergistically treat coal gangue according to claim 1, wherein In step S2, the fixed carbon content of the mixture is maintained at 2% - 10%; more preferably, the fixed carbon content of the mixture is maintained at 2% - 6.5%.

6. The method for preparing an active cementitious material by using calcium-based solid waste to synergistically prepare gangue according to claim 1, characterized in that In step S3, a rotary drum pelletizer is used for pelletizing. The rotational speed of the rotary drum pelletizer is 20 - 40 rpm, and the pelletizing time is 3 - 7 min; the moisture content of the green pellet particles obtained by pelletizing is 6% - 11%, and the particle size is 3 - 10 mm.

7. The method for preparing an active cementitious material by using calcium-based solid waste to synergistically treat coal gangue according to claim 1, characterized in that In step S4, control the thickness of the bottom layer to be 15 - 70 mm, and the particle size of the bottom layer to be 15 - 25 mm. If the fixed carbon content of the gangue < 5%, the original gangue after crushing is used as the bottom layer; if the fixed carbon content of the gangue ≥ 5%, the crushed finished ore is used as the bottom layer to prevent the bottom layer temperature from being too high and damaging the grate bars.

8. The method for preparing an active cementitious material by using calcium-based solid waste and coal gangue in combination according to claim 1, characterized in that, In step S4, during the batching process, control the total layer height to be 900 - 2000 mm.

9. The method for preparing an active cementitious material by synergistically using calcium-based solid waste and coal gangue according to claim 1, characterized in that, In step S4, the ignition time is 1 - 5 min, the ignition temperature is 950 - 1150 °C, and the ignition negative pressure is 4 - 6 kPa; the heat preservation temperature is 800 - 900 °C, and the heat preservation time is 3 - 6 min; the negative pressure during suction sintering is 9 - 18 kPa; the cooling time is 5 - 10 min, and the cooling negative pressure is 5 - 15 kPa.

10. The method for preparing an active cementitious material by synergistically using calcium-based solid waste and coal gangue according to claim 1, characterized in that, In step S5, the finished ore is crushed and finely ground to obtain an active cementitious material, and the properties of the active cementitious material are as follows: the proportion of particles with a size of -0.08 mm is 97% - 99%, the loss on ignition is ≤ 3%, the residual carbon content is ≤ 3%, the specific surface area is 300 - 400 m 2 / kg, and the activity index is ≥ 70%.

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