A modified limestone-derived carbon dioxide adsorbent for coal-fired solid waste and its preparation method

Abstract

This invention provides a modified limestone-derived carbon dioxide adsorbent from coal-fired solid waste and its preparation method. The preparation method includes: dry mixing limestone with coal-fired solid waste to obtain limestone-derived powder; and / or calcining limestone, mixing it with water, and then drying it to obtain slaked lime; dry mixing the slaked lime with coal-fired solid waste to obtain limestone-derived powder; mixing the limestone-derived powder with microcrystalline cellulose, and then mixing it with water to obtain a wet mixture; extruding and spheroidizing the wet mixture, and then drying and sieving it to obtain the modified limestone-derived carbon dioxide adsorbent from coal-fired solid waste. The modified limestone-derived carbon dioxide adsorbent from coal-fired solid waste of this invention is prepared by this method. This invention utilizes fly ash and desulfurization gypsum, the main solid waste generated from coal combustion, to prepare a modified limestone-derived CO2 adsorbent from coal-fired solid waste, making it more suitable for CaL systems while simultaneously absorbing the main solid waste from coal-fired power plants.

Description

Technical Field

[0001] This invention relates to a modified limestone-derived carbon dioxide adsorbent for coal-fired solid waste and its preparation method, belonging to the technical field of high-temperature CO2 capture adsorbent materials. Background Technology

[0002] Excessive CO2 emissions from fossil fuel combustion are a major cause of global warming. To prevent further deterioration of environmental and climate problems caused by global warming, many technologies for reducing CO2 emissions have been developed. Among them, carbon capture and storage (CCS) is a promising method that achieves the sustainable use of fossil fuels by capturing and storing CO2. Calcium cycling (CaL) technology, as a post-combustion CO2 capture technology, has advantages such as wide availability of raw materials, low cost, and broad applicability. Limestone is a natural, low-cost calcium-based adsorbent. Although the theoretical CO2 adsorption capacity of calcium-based adsorbents is as high as ~0.786 g CO2 / g CaO, their CO2 capture performance deteriorates rapidly during high-temperature cycling.

[0003] The most common strategy for preparing highly efficient calcium-based adsorbents suitable for practical CaL systems is to combine inert additives with granulation. Calcium aluminate cement and naturally occurring aluminosilicate minerals have attracted widespread attention as inert stabilizers for calcium-based modified adsorbents due to their low cost.

[0004] Currently, calcium-based adsorbents modified with inert additives suffer from easy elution, resulting in low practicality in fluidized bed CaL systems, and their CO2 capture stability needs further improvement.

[0005] Therefore, it is necessary to modify limestone solid carbon dioxide adsorbents to provide a novel type of carbon dioxide adsorbent. Summary of the Invention

[0006] To address the aforementioned technical problems, the present invention aims to provide a modified limestone-derived carbon dioxide adsorbent for coal-fired solid waste and its preparation method. This invention utilizes two main types of coal-fired solid waste generated from coal combustion—fly ash and desulfurization gypsum—to prepare a modified limestone-derived CO2 adsorbent, making it more suitable for CaL systems while effectively utilizing the main solid waste generated by coal-fired power plants.

[0007] To achieve the above objectives, the first aspect of the present invention provides a method for preparing a modified limestone-derived carbon dioxide adsorbent from coal-fired solid waste, comprising the following steps:

[0008] (1) Limestone is dry-mixed with coal-fired solid waste to obtain limestone-derived powder; and / or, limestone is calcined, mixed with water, and then dried to obtain slaked lime, and the slaked lime is dry-mixed with coal-fired solid waste to obtain limestone-derived powder; wherein, the coal-fired solid waste includes fly ash and desulfurized gypsum.

[0009] (2) Mix the limestone-derived powder obtained in step (1) with microcrystalline cellulose, and then mix with water to obtain a wet mixture;

[0010] (3) The wet mixture obtained in step (2) is extruded and rolled into a ball, then dried and sieved to obtain the modified limestone-derived carbon dioxide adsorbent for coal-fired solid waste.

[0011] In the above preparation method, preferably, in step (1), based on the total mass of the fly ash as 100%, the content of SiO2 is 45-52% (more preferably 47-48%) and the content of Al2O3 is 30-45% (more preferably 40-41%); in step (1), based on the total mass of the desulfurized gypsum as 100%, the content of CaSO4·2H2O is 90-95% and the content of CaCO3 is 0.5-5% (more preferably 1-5%).

[0012] In the above preparation method, preferably, in step (1), the main components of the coal-fired solid waste (which includes fly ash and desulfurization gypsum) and the limestone include:

[0013]

[0014] The blank areas indicate that the virus was not detected.

[0015] In the above preparation method, in step (1), the mass ratio of fly ash to desulfurized gypsum can be based on the ratio of the two solid wastes actually generated by the coal-fired power plant; preferably, the mass ratio of fly ash to desulfurized gypsum is 6:1 to 3:1.

[0016] In the above preparation method, preferably, in step (1), the mass ratio of limestone to the coal-fired solid waste, based on the mass of calcium oxide, is (80-95):(20-5), for example 95:5, 90:10, 85:15 or 80:20.

[0017] In the above preparation method, preferably, in step (1), the mass ratio of the quicklime to the coal-fired solid waste, based on the mass of calcium oxide, is (80-95):(20-5), for example 95:5, 90:10, 85:15 or 80:20.

[0018] In the above preparation method, preferably, in step (1), the calcination temperature of the limestone is 900-1000℃ and the calcination time is 1-10h.

[0019] In the above preparation method, preferably, in step (1), the drying temperature of the quicklime is 100-110°C.

[0020] In the above preparation method, preferably, in step (2), the mass ratio of the limestone-derived powder to the microcrystalline cellulose is (20:1) to (5:1), more preferably 10:1.

[0021] In the above preparation method, preferably, in step (3), the speed of the extruder used for extrusion and rounding is 90-100 rpm, and the speed of the rounding machine is 1100-1300 rpm.

[0022] In the above preparation method, preferably, in step (3), the drying is carried out in a constant temperature forced-air drying oven at a temperature of 100-120°C for 3-8 hours.

[0023] In the above preparation method, preferably, in step (3), the particle size of the adsorbent obtained after sieving is 0.9 to 1.25 mm.

[0024] According to a specific embodiment of the present invention, preferably, the above preparation method further includes step (4): calcining the adsorbent obtained in step (3) at a temperature of 800-900°C for a time of 5-30 min. More preferably, the calcination specifically includes: heating the adsorbent to 800-900°C in an air atmosphere at a heating rate of 10-15°C / min, and then holding it for 5-30 min.

[0025] A second aspect of the present invention provides a modified limestone-derived carbon dioxide adsorbent for coal-fired solid waste, which is prepared by the above-described preparation method.

[0026] According to a specific embodiment of the present invention, preferably, the particle size of the modified limestone-derived carbon dioxide adsorbent for coal-fired solid waste is 0.9 to 1.25 mm.

[0027] According to a specific embodiment of the present invention, preferably, the compressive strength of the coal-fired solid waste modified limestone-derived carbon dioxide adsorbent prepared by dry mixing limestone and coal-fired solid waste to obtain limestone-derived powder is 0.34-1.96 MPa; the compressive strength of the coal-fired solid waste modified limestone-derived carbon dioxide adsorbent prepared by dry mixing slaked lime and coal-fired solid waste to obtain limestone-derived powder is 4.3-7.7 MPa.

[0028] This invention provides a modified limestone-derived carbon dioxide adsorbent from coal-fired solid waste and its preparation method. The invention uses natural limestone as the main source of calcium in the adsorbent; the main component of fly ash, a major solid waste generated by coal-fired power plants, is similar to naturally occurring aluminosilicate minerals; and desulfurization gypsum, another solid waste generated by coal-fired power plants, supplements the calcium in the adsorbent, thus reducing the amount of natural limestone used, while effectively controlling the leaching of heavy metals from the adsorbent, thereby reducing the environmental risk of the product. This invention uses coal-fired solid waste (fly ash and desulfurization gypsum) as the modifying material for the limestone-derived adsorbent. By improving the ratio of limestone and / or quicklime obtained after calcination and hydration to coal-fired solid waste, and by improving the mixing method to a dry mixing method, introducing microcrystalline cellulose, and improving the granulation method to an extrusion spheroidization granulation method, a modified limestone-derived CO2 adsorbent from coal-fired solid waste is prepared, making it more suitable for CaL systems.

[0029] In fluidized bed-based calcium circulation (CaL) systems, limestone typically exhibits poor CO2 capture stability and severe elution problems during circulation. This invention addresses this issue by synthesizing two coal-ash-bound (CFA-bound) limestone-based adsorbents through separate mixing of limestone and slaked lime with coal combustion solid waste. In the adsorbents of this invention, the generated Ca-Al-O and Ca-Si-O ternary phases provide structural stability to the limestone-derived adsorbents, improving their compressive strength and CO2 capture performance during circulation, while effectively reducing the environmental risk of the product.

[0030] The technical solution of the present invention has at least the following beneficial effects:

[0031] 1. By using solid waste (fly ash and desulfurization gypsum) generated after coal combustion in coal-fired power plants to modify limestone-derived CO2 adsorbents, the effect of solid waste resource utilization can be achieved.

[0032] 2. Improved the circulating CO2 capture capacity of limestone-derived CO2 adsorbents (C n ), carbonization conversion rate (X) n It improves compressive strength and reduces the environmental risks of the product. Attached Figure Description

[0033] Figure 1 This is a comparison chart showing the cyclic CO2 capture capacity of the adsorbents prepared in Comparative Examples 1 and 3 with those in Examples 1, 2, 3, and 4.

[0034] Figure 2 This is a comparison graph showing the cyclic CO2 capture capacity of the adsorbents prepared in Comparative Examples 2 and 4 with those in Examples 5, 6, 7, and 8.

[0035] Figure 3This is a comparison chart of the carbonization conversion rates of the adsorbents prepared in Comparative Examples 1 and 3 and Examples 1, 2, 3, and 4.

[0036] Figure 4 This is a comparison chart of the carbonization conversion rates of the adsorbents prepared in Comparative Examples 2 and 4 and Examples 5, 6, 7, and 8.

[0037] Figure 5 The graph shows a comparison of the compressive strength and total adsorption capacity of the adsorbents prepared in Comparative Examples 1 and 3 with those prepared in Examples 1, 2, 3, and 4.

[0038] Figure 6 The graph shows a comparison of the compressive strength and total adsorption capacity of the adsorbents prepared in Comparative Examples 2 and 4 with those prepared in Examples 5, 6, 7, and 8.

[0039] Figure 7 The graph shows a comparison of the compressive strength and carbonization conversion rate after cycling of the adsorbents prepared in Comparative Examples 1-2 and Examples 1-8.

[0040] Figure 8 This is a comparison chart of the leaching toxicity values ​​of Hg and As in the adsorbents prepared in Comparative Examples 1 and 3 and Examples 1, 2, 3, and 4.

[0041] Figure 9 This is a comparison chart of the leaching toxicity values ​​of Hg and As in the adsorbents prepared in Comparative Examples 2 and 4 and Examples 5, 6, 7, and 8. Detailed Implementation

[0042] In order to provide a clearer understanding of the technical features, objectives and beneficial effects of the present invention, the technical solution of the present invention will now be described in detail below, but it should not be construed as limiting the scope of implementation of the present invention.

[0043] Unless otherwise specified, the techniques or conditions described in the following examples are based on those described in the prior art. Reagents or instruments used, unless otherwise specified, are all commercially available products.

[0044] In the following examples and comparative examples, the cyclic CO2 capture capability (C n ), carbonization conversion rate (X) n ), compressive strength of the adsorbent Calculate using the following formula:

[0045]

[0046]

[0047]

[0048]

[0049] In the above formula, and These refer to the adsorption mass during the nth carbonization and calcination processes, respectively; σ refers to the content of active calcium oxide in the adsorbent; M CaO and These refer to the molar mass of calcium oxide and the molar mass of CO2, respectively; F m，i It is the maximum pressure (N) required to break a single adsorbent particle; This refers to the average diameter (mm) of the adsorbent particles; P c，i This refers to the compressive strength (MPa) of each particle; P refers to each group c，i The average value (MPa). It should be noted that the content of active calcium oxide in the adsorbent (σ) is calculated based on the content of active calcium oxide in the raw material. Due to the complexity of the reaction process, the calculation formula of this invention assumes that the content of active calcium oxide has not decreased, but in reality it has decreased. Considering the partial consumption of active calcium oxide, the actual calcium oxide carbonization conversion rate is higher than the conversion rate calculated according to the above formula.

[0050] Example 1

[0051] This embodiment provides a modified limestone-derived CO2 adsorbent for coal-fired solid waste, the preparation method of which includes the following steps:

[0052] (1) Weigh 17.24g of limestone sample and 0.5g of coal-fired solid waste sample (which consists of fly ash and desulfurized gypsum, with a mass ratio of fly ash to desulfurized gypsum of 4:1; based on the total mass of the fly ash as 100%, the content of SiO2 is 47.4wt% and the content of Al2O3 is 40.3wt%; based on the total mass of the desulfurized gypsum as 100%, the content of CaSO4·2H2O is 91.3% and the content of CaCO3 is 2.5%). The mixing mass ratio of the limestone sample to the coal-fired solid waste sample based on the mass of calcium oxide is approximately 95:5. Put them into a sealed bag and dry mix them to make them evenly mixed to obtain limestone-derived powder.

[0053] The main components of the coal-fired solid waste (fly ash and desulfurization gypsum) and the limestone include:

[0054]

[0055] The blank areas indicate that the substance was not detected.

[0056] (2) The limestone-derived powder obtained in step (1) is mixed with microcrystalline cellulose at a mass ratio of 10:1 to obtain a solid mixture. An appropriate amount of water is added to the solid mixture and stirred to form a uniform wet mixture.

[0057] (3) The wet mixture obtained in step (2) is extruded and rolled into rounds. The speed of the extruder is 90-100 rpm and the speed of the rounding machine is 1100-1300 rpm. Then it is dried in a constant temperature drying oven at 110℃ for 6 hours. Then it is sieved and particles with a particle size of 0.9-1.25 mm are collected to obtain a uniformly sized modified limestone-derived CO2 adsorbent for coal-fired solid waste.

[0058] The adsorbent, after calcination, captures CO2. The specific process includes: taking 15-20 mg of the adsorbent obtained in step (3) and placing it in a thermogravimetric analyzer for a cyclic CO2 capture test, testing 17 carbonization / calcination cycles; during the calcination stage, the sample in the crucible is first heated to 850°C at a rate of 10°C / min and then held for 10 min; then the sample is cooled to 650°C at a rate of 10°C / min and held for 20 min to capture CO2; then the sample temperature is raised to 850°C again for the next cycle; during the carbonization / calcination cycle, 15 vol% CO2 and 85 vol% N2 (total gas flow rate of 100 mL / min) are sent to the thermogravimetric analyzer. The data are analyzed to obtain the cyclic CO2 capture capacity (C) of the adsorbent. n ) and carbonization conversion rate (X n ),like Figure 1 and Figure 3 As shown.

[0059] Twenty adsorbent samples obtained in step (3) were taken for pressure testing, and their compressive strength was calculated to be 0.9 ± 0.41 MPa after statistical analysis.

[0060] The compressive strength and total adsorption capacity of the adsorbent in this embodiment are as follows: Figure 5 As shown. In Figure 5 In the graph, the bars represent compressive strength, and the dots represent total adsorption capacity.

[0061] Example 2

[0062] This embodiment provides a modified limestone-derived CO2 adsorbent for coal-fired solid waste, the preparation method of which includes the following steps:

[0063] (1) Weigh 16.34g of limestone sample and 1g of coal-fired solid waste sample (which consists of fly ash and desulfurized gypsum, with a mass ratio of fly ash to desulfurized gypsum of 4:1; based on the total mass of the fly ash as 100%, the content of SiO2 is 47.4wt% and the content of Al2O3 is 40.3wt%; based on the total mass of the desulfurized gypsum as 100%, the content of CaSO4·2H2O is 91.3% and the content of CaCO3 is 2.5%). The mixing mass ratio of the limestone sample (calcium oxide) to the coal-fired solid waste sample is approximately 90:10. Place them in a sealed bag and dry mix them to ensure uniform mixing, thereby obtaining limestone-derived powder. The main components of the coal-fired solid waste (fly ash and desulfurized gypsum) and the limestone are the same as in Example 1.

[0064] (2) The limestone-derived powder obtained in step (1) is mixed with microcrystalline cellulose at a mass ratio of 10:1 to obtain a solid mixture. An appropriate amount of water is added to the solid mixture and stirred to form a uniform wet mixture.

[0065] (3) The wet mixture obtained in step (2) is extruded and rolled into rounds. The speed of the extruder is 90-100 rpm and the speed of the rounding machine is 1100-1300 rpm. Then it is dried in a constant temperature drying oven at 110℃ for 6 hours. Then it is sieved and particles with a particle size of 0.9-1.25 mm are collected to obtain a uniformly sized modified limestone-derived CO2 adsorbent for coal-fired solid waste.

[0066] The adsorbent, after calcination, captures CO2, following the same process as in Example 1. Data analysis yielded the adsorbent's circulating CO2 capture capacity (C). n ) and carbonization conversion rate (X n ),like Figure 1 and Figure 3 As shown.

[0067] Twenty adsorbent samples obtained in step (3) were taken for pressure testing, and their compressive strength was calculated to be 0.8 ± 0.36 MPa after statistical analysis.

[0068] The compressive strength and total adsorption capacity of the adsorbent in this embodiment are as follows: Figure 5 As shown.

[0069] Example 3

[0070] This embodiment provides a modified limestone-derived CO2 adsorbent for coal-fired solid waste, the preparation method of which includes the following steps:

[0071] (1) Weigh 15.30g of limestone sample and 1.5g of coal-fired solid waste sample (which consists of fly ash and desulfurized gypsum, with a mass ratio of fly ash to desulfurized gypsum of 4:1; based on the total mass of the fly ash as 100%, the content of SiO2 is 47.4wt% and the content of Al2O3 is 40.3wt%; based on the total mass of the desulfurized gypsum as 100%, the content of CaSO4·2H2O is 91.3% and the content of CaCO3 is 2.5%). The mixing mass ratio of the limestone sample (calcium oxide) to the coal-fired solid waste sample is approximately 85:15. Place them in a sealed bag and dry mix them to ensure uniform mixing, thereby obtaining limestone-derived powder. The main components of the coal-fired solid waste (fly ash and desulfurized gypsum) and the limestone are the same as in Example 1.

[0072] (2) The limestone-derived powder obtained in step (1) is mixed with microcrystalline cellulose at a mass ratio of 10:1 to obtain a solid mixture. An appropriate amount of water is added to the solid mixture and stirred to form a uniform wet mixture.

[0073] (3) The wet mixture obtained in step (2) is extruded and rolled into rounds. The speed of the extruder is 90-100 rpm and the speed of the rounding machine is 1100-1300 rpm. Then it is dried in a constant temperature drying oven at 110℃ for 6 hours. Then it is sieved and particles with a particle size of 0.9-1.25 mm are collected to obtain a uniformly sized modified limestone-derived CO2 adsorbent for coal-fired solid waste.

[0074] The adsorbent, after calcination, captures CO2, following the same process as in Example 1. Data analysis yielded the adsorbent's circulating CO2 capture capacity (C). n ) and carbonization conversion rate (X n ),like Figure 1 and Figure 3 As shown.

[0075] Twenty adsorbent samples obtained in step (3) were taken for pressure testing, and their compressive strength was calculated to be 0.7 ± 0.36 MPa after statistical analysis.

[0076] The compressive strength and total adsorption capacity of the adsorbent in this embodiment are as follows: Figure 5 As shown.

[0077] Example 4

[0078] This embodiment provides a modified limestone-derived CO2 adsorbent for coal-fired solid waste, the preparation method of which includes the following steps:

[0079] (1) Weigh 14.53g of limestone sample and 2g of coal-fired solid waste sample (which consists of fly ash and desulfurized gypsum, with a mass ratio of fly ash to desulfurized gypsum of 4:1; based on the total mass of the fly ash as 100%, the content of SiO2 is 47.4wt% and the content of Al2O3 is 40.3wt%; based on the total mass of the desulfurized gypsum as 100%, the content of CaSO4·2H2O is 91.3% and the content of CaCO3 is 2.5%). The mixing mass ratio of the limestone sample (calcium oxide) to the coal-fired solid waste sample is approximately 80:20. Place them in a sealed bag and dry mix them to ensure uniform mixing, thereby obtaining limestone-derived powder. The main components of the coal-fired solid waste (fly ash and desulfurized gypsum) and the limestone are the same as in Example 1.

[0080] (2) The limestone-derived powder obtained in step (1) is mixed with microcrystalline cellulose at a mass ratio of 10:1 to obtain a solid mixture. An appropriate amount of water is added to the solid mixture and stirred to form a uniform wet mixture.

[0081] (3) The wet mixture obtained in step (2) is extruded and rolled into rounds. The speed of the extruder is 90-100 rpm and the speed of the rounding machine is 1100-1300 rpm. Then it is dried in a constant temperature drying oven at 110℃ for 6 hours. Then it is sieved and particles with a particle size of 0.9-1.25 mm are collected to obtain a uniformly sized modified limestone-derived CO2 adsorbent for coal-fired solid waste.

[0082] The adsorbent, after calcination, captures CO2, following the same process as in Example 1. Data analysis yielded the adsorbent's circulating CO2 capture capacity (C). n ) and carbonization conversion rate (X n ),like Figure 1 and Figure 3 As shown.

[0083] Twenty adsorbent samples obtained in step (3) were taken for pressure testing, and their compressive strength was calculated to be 1.6 ± 0.36 MPa after statistical analysis.

[0084] The compressive strength and total adsorption capacity of the adsorbent in this embodiment are as follows: Figure 5 As shown.

[0085] Example 5

[0086] This embodiment provides a modified limestone-derived CO2 adsorbent for coal-fired solid waste, the preparation method of which includes the following steps:

[0087] (1) Limestone was calcined at 900℃ for 1.5h, then mixed with deionized water and stirred with a glass rod, and then dried to obtain slaked lime; 12.55g of the dried slaked lime and 0.5g of the coal-fired solid waste sample (which is composed of fly ash and desulfurized gypsum, with a mass ratio of fly ash to desulfurized gypsum of 4:1; based on the total mass of the fly ash as 100%, the content of SiO2 is 47.4wt% and the content of Al2O3 is 40.3wt%; based on the total mass of the desulfurized gypsum as 100%, the content of CaSO4·2H2O is 91.3% and the content of CaCO3 is 2.5%) were weighed, and the mixing mass ratio of the slaked lime (calcium oxide) to the coal-fired solid waste sample was approximately 95:5. The samples were placed in a sealed bag and dry-mixed to ensure uniform mixing, thus obtaining limestone-derived powder; wherein, the main components of the coal-fired solid waste (fly ash and desulfurized gypsum) and the limestone are the same as in Example 1.

[0088] (2) The limestone-derived powder obtained in step (1) is mixed with microcrystalline cellulose at a mass ratio of 10:1 to obtain a solid mixture. An appropriate amount of water is added to the solid mixture and stirred to form a uniform wet mixture.

[0089] (3) The wet mixture obtained in step (2) is extruded and rolled into rounds. The speed of the extruder is 90-100 rpm and the speed of the rounding machine is 1100-1300 rpm. Then it is dried in a constant temperature drying oven at 110℃ for 6 hours. Then it is sieved and particles with a particle size of 0.9-1.25 mm are collected to obtain a uniformly sized modified limestone-derived CO2 adsorbent for coal-fired solid waste.

[0090] The adsorbent, after calcination, captures CO2, following the same process as in Example 1. Data analysis yielded the adsorbent's circulating CO2 capture capacity (C). n ) and carbonization conversion rate (X n ),like Figure 2 and Figure 4 As shown.

[0091] Twenty adsorbent samples obtained in step (3) were taken for pressure testing, and their compressive strength was calculated to be 6 ± 1.2 MPa after statistical analysis.

[0092] The compressive strength and total adsorption capacity of the adsorbent in this embodiment are as follows: Figure 6 As shown. In Figure 6 In the graph, the bars represent compressive strength, and the dots represent total adsorption capacity.

[0093] Example 6

[0094] This embodiment provides a modified limestone-derived CO2 adsorbent for coal-fired solid waste, the preparation method of which includes the following steps:

[0095] (1) Limestone was calcined at 900℃ for 1.5h, then mixed with deionized water and stirred with a glass rod, and then dried to obtain slaked lime; 11.89g of the dried slaked lime and 1g of coal-fired solid waste sample (which is composed of fly ash and desulfurized gypsum, with a mass ratio of fly ash to desulfurized gypsum of 4:1; based on the total mass of the fly ash as 100%, the content of SiO2 is 47.4wt% and the content of Al2O3 is 40.3wt%; based on the total mass of the desulfurized gypsum as 100%, the content of CaSO4·2H2O is 91.3% and the content of CaCO3 is 2.5%) were weighed, and the mixing mass ratio of the slaked lime (calcium oxide) to the coal-fired solid waste sample was approximately 90:10. They were placed in a sealed bag and dry-mixed to ensure uniform mixing, thus obtaining limestone-derived powder; wherein, the main components of the coal-fired solid waste (fly ash and desulfurized gypsum) and the limestone are the same as in Example 1.

[0096] (2) The limestone-derived powder obtained in step (1) is mixed with microcrystalline cellulose at a mass ratio of 10:1 to obtain a solid mixture. An appropriate amount of water is added to the solid mixture and stirred to form a uniform wet mixture.

[0097] (3) The wet mixture obtained in step (2) is extruded and rolled into rounds. The speed of the extruder is 90-100 rpm and the speed of the rounding machine is 1100-1300 rpm. Then it is dried in a constant temperature drying oven at 110℃ for 6 hours. Then it is sieved and particles with a particle size of 0.9-1.25 mm are collected to obtain a uniformly sized modified limestone-derived CO2 adsorbent for coal-fired solid waste.

[0098] The adsorbent, after calcination, captures CO2, following the same process as in Example 1. Data analysis yielded the adsorbent's circulating CO2 capture capacity (C). n ) and carbonization conversion rate (X n ),like Figure 2 and Figure 4 As shown.

[0099] Twenty adsorbent samples obtained in step (3) were taken for pressure testing, and their compressive strength was calculated to be 6 ± 1.4 MPa after statistical analysis.

[0100] The compressive strength and total adsorption capacity of the adsorbent in this embodiment are as follows: Figure 6 As shown.

[0101] Example 7

[0102] This embodiment provides a modified limestone-derived CO2 adsorbent for coal-fired solid waste, the preparation method of which includes the following steps:

[0103] (1) Limestone was calcined at 900℃ for 1.5h, then mixed with deionized water and stirred with a glass rod, and then dried to obtain slaked lime; 11.23g of the dried slaked lime was weighed, and a coal-fired solid waste sample (composed of fly ash and desulfurized gypsum, with a mass ratio of fly ash to desulfurized gypsum of 4:1; based on the total mass of the fly ash as 100%, the content of SiO2 was 47.4wt% and the content of Al2O3 was 40.3wt% ... and the content of Al2O3 was 40.3wt%. The total mass of sulfur gypsum (calculated as 100%, containing 91.3% CaSO4·2H2O and 2.5% CaCO3) was 1.5g. The quicklime, calculated by mass of calcium oxide, was mixed with the coal-fired solid waste sample at a mass ratio of approximately 85:15. The mixture was placed in a sealed bag and dry-mixed to ensure uniform mixing, resulting in limestone-derived powder. The main components of the coal-fired solid waste (fly ash and desulfurized gypsum) and the limestone were the same as in Example 1.

[0104] (2) The limestone-derived powder obtained in step (1) is mixed with microcrystalline cellulose at a mass ratio of 10:1 to obtain a solid mixture. An appropriate amount of water is added to the solid mixture and stirred to form a uniform wet mixture.

[0105] (3) The wet mixture obtained in step (2) is extruded and rolled into rounds. The speed of the extruder is 90-100 rpm and the speed of the rounding machine is 1100-1300 rpm. Then it is dried in a constant temperature drying oven at 110℃ for 6 hours. Then it is sieved and particles with a particle size of 0.9-1.25 mm are collected to obtain a uniformly sized modified limestone-derived CO2 adsorbent for coal-fired solid waste.

[0106] The adsorbent, after calcination, captures CO2, following the same process as in Example 1. Data analysis yielded the adsorbent's circulating CO2 capture capacity (C). n ) and carbonization conversion rate (X n ),like Figure 2 and Figure 4 As shown.

[0107] Twenty adsorbent samples obtained in step (3) were taken for pressure testing, and their compressive strength was calculated to be 6 ± 1.7 MPa after statistical analysis.

[0108] The compressive strength and total adsorption capacity of the adsorbent in this embodiment are as follows: Figure 6 As shown.

[0109] Example 8

[0110] This embodiment provides a modified limestone-derived CO2 adsorbent for coal-fired solid waste, the preparation method of which includes the following steps:

[0111] (1) Limestone was calcined at 900℃ for 1.5h, then mixed with deionized water and stirred with a glass rod, and then dried to obtain slaked lime; 10.57g of the dried slaked lime and 2g of coal-fired solid waste sample (which is composed of fly ash and desulfurized gypsum, with a mass ratio of fly ash to desulfurized gypsum of 4:1; based on the total mass of the fly ash as 100%, the content of SiO2 is 47.4wt% and the content of Al2O3 is 40.3wt%; based on the total mass of the desulfurized gypsum as 100%, the content of CaSO4·2H2O is 91.3% and the content of CaCO3 is 2.5%) were weighed, and the mixing mass ratio of the slaked lime (calcium oxide) to the coal-fired solid waste sample was approximately 80:20. They were placed in a sealed bag and dry-mixed to ensure uniform mixing, thus obtaining limestone-derived powder; wherein, the main components of the coal-fired solid waste (fly ash and desulfurized gypsum) and the limestone are the same as in Example 1.

[0112] (2) The limestone-derived powder obtained in step (1) is mixed with microcrystalline cellulose at a mass ratio of 10:1 to obtain a solid mixture. An appropriate amount of water is added to the solid mixture and stirred to form a uniform wet mixture.

[0113] (3) The wet mixture obtained in step (2) is extruded and rolled into rounds. The speed of the extruder is 90-100 rpm and the speed of the rounding machine is 1100-1300 rpm. Then it is dried in a constant temperature drying oven at 110℃ for 6 hours. Then it is sieved and particles with a particle size of 0.9-1.25 mm are collected to obtain a uniformly sized modified limestone-derived CO2 adsorbent for coal-fired solid waste.

[0114] The adsorbent, after calcination, captures CO2, following the same process as in Example 1. Data analysis yielded the adsorbent's circulating CO2 capture capacity (C). n ) and carbonization conversion rate (X n ),like Figure 2 and Figure 4 As shown.

[0115] Twenty adsorbent samples obtained in step (3) were taken for pressure testing, and their compressive strength was calculated to be 6 ± 1.6 MPa after statistical analysis.

[0116] The compressive strength and total adsorption capacity of the adsorbent in this embodiment are as follows: Figure 6 As shown.

[0117] Comparative Example 1

[0118] This comparative example provides a pure limestone CO2 adsorbent, the preparation method of which includes the following steps:

[0119] (1) Weigh 20g of limestone sample and 2g of microcrystalline cellulose, put them into a sealed bag and dry mix them to make them evenly mixed to obtain a solid mixture; wherein, the main components of the limestone are the same as in Example 1;

[0120] (2) Add an appropriate amount of water to the solid mixture obtained in step (1) and stir to form a uniform wet mixture;

[0121] (3) The wet mixture obtained in step (2) is extruded and rolled into rounds. The speed of the extruder is 90-100 rpm and the speed of the rounding machine is 1100-1300 rpm. Then it is dried in a constant temperature drying oven at 110℃ for 6 hours. Then it is sieved and particles with a particle size of 0.9-1.25 mm are collected to obtain pure limestone CO2 adsorbent with uniform particle size.

[0122] The adsorbent, after calcination, captures CO2, following the same process as in Example 1. Data analysis yielded the adsorbent's circulating CO2 capture capacity (C). n ) and carbonization conversion rate (X n ),like Figure 1 and Figure 3 As shown.

[0123] Twenty adsorbent samples obtained in step (3) were taken for pressure testing, and their compressive strength was calculated to be 0.6 ± 0.25 MPa after statistical analysis.

[0124] The compressive strength and total adsorption capacity of the adsorbent in this comparative example are as follows: Figure 5 As shown.

[0125] Comparative Example 2

[0126] This comparative example provides a quicklime CO2 adsorbent obtained by calcining and hydrating limestone, and its preparation method includes the following steps:

[0127] (1) Calcining limestone at 900℃ for 1.5h, then mixing it with deionized water and stirring with a glass rod, and then drying it to obtain slaked lime; weighing 20g of dried slaked lime and 2g of microcrystalline cellulose, putting them into a sealed bag for dry mixing, so that they are evenly mixed to obtain a solid mixture; wherein, the main components of the limestone are the same as in Example 1.

[0128] (2) Add an appropriate amount of water to the solid mixture obtained in step (1) and stir to form a uniform wet mixture;

[0129] (3) The wet mixture obtained in step (2) is extruded and rolled into rounds. The speed of the extruder is 90-100 rpm and the speed of the rounding machine is 1100-1300 rpm. Then it is dried in a constant temperature drying oven at 110℃ for 6 hours. Then it is sieved and particles with a particle size of 0.9-1.25 mm are collected to obtain a hydrated lime CO2 adsorbent with uniform particle size.

[0130] The adsorbent, after calcination, captures CO2, following the same process as in Example 1. Data analysis yielded the adsorbent's circulating CO2 capture capacity (C). n ) and carbonization conversion rate (X n ),like Figure 2 and Figure 4 As shown.

[0131] Twenty adsorbent samples obtained in step (3) were taken for pressure testing, and their compressive strength was calculated to be 4 ± 1.5 MPa after statistical analysis.

[0132] The compressive strength and total adsorption capacity of the adsorbent in this comparative example are as follows: Figure 6 As shown.

[0133] Comparative Example 3

[0134] This comparative example provides a fly ash-modified limestone-derived CO2 adsorbent, the preparation method of which includes the following steps:

[0135] (1) Weigh 16.34g of limestone sample and 1.0g of fly ash sample (based on the total mass of the fly ash as 100%, the content of SiO2 is 47.4wt% and the content of Al2O3 is 40.3wt%). The mixing mass ratio of the limestone sample to the fly ash sample based on the mass of calcium oxide is approximately 90:10. Place them in a sealed bag and dry mix them to make them uniformly mixed to obtain limestone-derived powder. The main components of the fly ash and the limestone are the same as in Example 1.

[0136] (2) The limestone-derived powder obtained in step (1) is mixed with microcrystalline cellulose at a mass ratio of 10:1 to obtain a solid mixture. An appropriate amount of water is added to the solid mixture and stirred to form a uniform wet mixture.

[0137] (3) The wet mixture obtained in step (2) is extruded and rolled into rounds. The speed of the extruder is 90-100 rpm and the speed of the rounding machine is 1100-1300 rpm. Then it is dried in a constant temperature drying oven at 110℃ for 6 hours. Then it is sieved and particles with a particle size of 0.9-1.25 mm are collected to obtain a fly ash modified limestone-derived CO2 adsorbent with uniform particle size.

[0138] The adsorbent, after calcination, captures CO2, following the same process as in Example 1. Data analysis yielded the adsorbent's circulating CO2 capture capacity (C). n ) and carbonization conversion rate (Xn), such as Figure 1 and Figure 3 As shown.

[0139] Twenty adsorbent samples obtained in step (3) were taken for pressure testing, and their compressive strength was calculated to be 0.4 ± 0.40 MPa after statistical analysis.

[0140] The compressive strength and total adsorption capacity of the adsorbent in this comparative example are as follows: Figure 5 As shown.

[0141] Comparative Example 4

[0142] This comparative example provides a desulfurized gypsum-modified limestone-derived CO2 adsorbent, the preparation method of which includes the following steps:

[0143] (1) Limestone was calcined at 900℃ for 1.5h, then mixed with deionized water and stirred with a glass rod, and then dried to obtain slaked lime; 11.89g of the dried slaked lime and 1.0g of the desulfurized gypsum sample (based on the total mass of the desulfurized gypsum as 100%, the content of CaSO4·2H2O is 91.3% and the content of CaCO3 is 2.5%) were weighed, and the mixing mass ratio of the slaked lime to the desulfurized gypsum sample based on the mass of calcium oxide was approximately 90:10. They were placed in a sealed bag and dry-mixed to make them uniformly mixed to obtain limestone-derived powder; wherein, the main components of the desulfurized gypsum and the limestone are the same as in Example 1;

[0144] (2) The limestone-derived powder obtained in step (1) is mixed with microcrystalline cellulose at a mass ratio of 10:1 to obtain a solid mixture. An appropriate amount of water is added to the solid mixture and stirred to form a uniform wet mixture.

[0145] (3) The wet mixture obtained in step (2) is extruded and rolled into rounds. The speed of the extruder is 90-100 rpm and the speed of the rounding machine is 1100-1300 rpm. Then it is dried in a constant temperature drying oven at 110℃ for 6 hours. Then it is sieved and particles with a particle size of 0.9-1.25 mm are collected to obtain a uniform particle size desulfurized gypsum modified limestone-derived CO2 adsorbent.

[0146] The adsorbent, after calcination, captures CO2, following the same process as in Example 1. Data analysis yielded the adsorbent's circulating CO2 capture capacity (C). n ) and carbonization conversion rate (X n ),like Figure 2 and Figure 4As shown.

[0147] Twenty adsorbent samples obtained in step (3) were taken for pressure testing, and their compressive strength was calculated to be 3 ± 1.2 MPa after statistical analysis.

[0148] The compressive strength and total adsorption capacity of the adsorbent in this comparative example are as follows: Figure 6 As shown.

[0149] Figure 7 This is a comparison chart of the compressive strength and carbonization conversion rate after cycling of the adsorbents prepared in Comparative Examples 1-2 and Examples 1-8 (the bars represent compressive strength, and the dots represent carbonization conversion rate after 17 cycles). Figures 1 to 7 As can be seen, this invention improves the circulating CO2 capture capacity (C2) of the limestone-derived CO2 adsorbent by using coal combustion solid waste as a modifying material for the limestone-derived adsorbent, improving the ratio of limestone or quicklime obtained from calcination and hydration of limestone to coal combustion solid waste, improving the mixing method, introducing microcrystalline cellulose, and improving the granulation method. n ), carbonization conversion rate (X) n Its high compressive strength makes it more suitable for CaL systems.

[0150] Figure 8 This is a comparison chart of the leaching toxicity values ​​of Hg and As in the adsorbents prepared in Comparative Examples 1 and 3 and Examples 1, 2, 3, and 4. Figure 9 This is a comparison graph showing the leaching toxicity values ​​of Hg and As in the adsorbents prepared in Comparative Examples 2 and 4 and Examples 5, 6, 7, and 8. (From...) Figures 8-9 It can be seen that by using coal combustion solid waste as a modifying material for limestone-derived adsorbents, the adsorbent prepared by this invention reduces the leaching toxicity values ​​of mercury and arsenic compared to limestone without the addition of coal combustion solid waste. Moreover, the greater the content of coal combustion solid waste added, the greater the reduction, thus reducing the environmental risk of the adsorbent. Meanwhile, comparative examples 2 and 4, which did not simultaneously add fly ash and desulfurization gypsum, could not effectively reduce the leaching toxicity of Hg and As in the adsorbent.

Claims

1. A method for preparing a modified limestone-derived carbon dioxide adsorbent from coal-fired solid waste, comprising the following steps: (1) Limestone is dry-mixed with coal-fired solid waste to obtain limestone-derived powder; and / or, limestone is calcined, mixed with water, and then dried to obtain slaked lime, and the slaked lime is dry-mixed with coal-fired solid waste to obtain limestone-derived powder; wherein, the coal-fired solid waste includes fly ash and desulfurized gypsum, and the mass ratio of fly ash to desulfurized gypsum is 6:1 to 3:1; the mass ratio of limestone to coal-fired solid waste based on the mass of calcium oxide is (80 to 95): (20 to 5); the mass ratio of slaked lime to coal-fired solid waste based on the mass of calcium oxide is (80 to 95): (20 to 5); (2) The limestone-derived powder obtained in step (1) is mixed with microcrystalline cellulose, wherein the mass ratio of the limestone-derived powder to the microcrystalline cellulose is (20:1) to (5:1), and then mixed with water to obtain a wet mixture; (3) The wet mixture obtained in step (2) is extruded and rolled into a ball, then dried and sieved to obtain the adsorbent; (4) The adsorbent obtained in step (3) is calcined at a temperature of 800~900℃ for 5~30min to obtain the modified limestone-derived carbon dioxide adsorbent for coal-fired solid waste.

2. The production method according to claim 1, wherein, In step (1), based on the total mass of the fly ash as 100%, the content of SiO2 is 45-52% and the content of Al2O3 is 30-45%; In step (1), the content of CaSO4 2H2O is 90-95%, and the content of CaCO3 is 0.5-5%.

3. The production method according to claim 1, wherein, In step (1), the calcination temperature of the limestone is 900~1000℃ and the calcination time is 1~10h.

4. The preparation method according to claim 1, wherein, In step (3), the extruder used for extrusion and rounding has a rotation speed of 90~100 rpm and the rounding machine has a rotation speed of 1100~1300 rpm.

5. The preparation method according to claim 1, wherein, In step (3), the particle size of the adsorbent obtained after sieving is 0.9~1.25 mm.

6. The preparation method according to claim 1, wherein, In step (4), the calcination specifically includes: heating the adsorbent to 800-900°C in an air atmosphere at a heating rate of 10-15°C / min, and then holding it for 5-30 minutes.

7. A modified limestone-derived carbon dioxide adsorbent for coal-fired solid waste, which is prepared by the preparation method according to any one of claims 1-6.

8. The modified limestone-derived carbon dioxide adsorbent for coal-fired solid waste according to claim 7, wherein, The particle size of the modified limestone-derived carbon dioxide adsorbent from coal-fired solid waste is 0.9~1.25mm.

9. The modified limestone-derived carbon dioxide adsorbent for coal-fired solid waste according to claim 7, wherein, The compressive strength of the coal-fired solid waste-modified limestone-derived carbon dioxide adsorbent prepared by dry mixing limestone with coal-fired solid waste to obtain limestone-derived powder is 0.34~1.96MPa; the compressive strength of the coal-fired solid waste-modified limestone-derived carbon dioxide adsorbent prepared by dry mixing hydrated lime with coal-fired solid waste to obtain limestone-derived powder is 4.3~7.7MPa.

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