A method for mineralizing and utilizing solid waste in the coal chemical industry and its application

Abstract

This application proposes a method for the mineralization utilization of solid waste in the coal chemical industry. This method uses ion doping technology to couple with mineralization technology, realizing the resource utilization of a large amount of solid waste aluminum extraction slag and waste gas CO2 while using the process of extracting aluminum from fly ash; through ion doping, the crystals of aluminum extraction slag from fly ash in the coal chemical industry are modified to improve the strength and carbon sequestration performance of mineralized products, so that the products can meet the requirements of building materials.

Description

Technical Field

[0001] The present invention relates to the technical field of solid waste resource utilization, B09B101 / 30, and in particular to a method for mineralization utilization of solid waste in coal chemical industry. Background Art

[0002] Fly ash is the main solid waste discharged from coal combustion, which contains a large amount of aluminum. Although the Al2O3 dissolution rate in the soda lime sintering method can reach 93.86%, the sintering process consumes a lot of energy, and 2.5-3.2 tons of high-silicon calcium aluminum slag will be produced for every 1 ton of fly ash sintered. Chinese patent CN107416874B removes the alkali in the fly ash aluminum slag and uses it to produce calcium silicate insulation materials or calcium silicate boards, thereby realizing the utilization of the silicon component in the fly ash, but the resource utilization of this technology is still insufficient.

[0003] Existing studies have been conducted to mineralize and fix CO2 by extracting aluminum-silicon-calcium slag from fly ash to achieve the resource utilization rate of fly ash. However, the calcium-silicon slag produced by the soda-lime sintering method is in block form and needs to be ground to a certain fineness to meet the requirements of the mineralization stage for calcium-silicon. The large amount of electricity consumed in the grinding process will further increase the processing cost, and the carbon fixation rate of the mineralization process is about 6-9%, and the degree of mineralization is limited. In addition, the mineralization product is mainly calcite calcium carbonate, and its strength does not meet the ideal standard, which limits the scope of application. Chinese patent CN113247914A proposes a method for preparing calcium-silicon oxide using aluminum-silicon oxide slag from fly ash. The prepared calcium-silicon oxide has a low thermal conductivity and can be used as a thermal insulation material, but the mechanical strength of the resource product is insufficient and its application is limited. Summary of the invention

[0004] In order to solve the above-mentioned technical problems, the present application proposes a method for the mineralization and utilization of solid waste in the coal chemical industry. The method of the present application adopts ion doping coupled mineralization technology, consumes a large amount of silicon-calcium slag and CO2 generated in the aluminum extraction process through mineralization reaction, and uses specific ratios of ion elements to dope and modify the aluminum extraction slag in the corresponding process stage, and cooperates with the mineralization process design to ensure the overall carbon fixation performance, mineralization efficiency and resource product strength, thereby providing a practical method for the mineralization and utilization of solid waste in the coal chemical industry for industrial production.

[0005] Furthermore, the method for mineralizing and utilizing solid waste in the coal chemical industry comprises: modifying high-temperature aluminum extraction slag with a dopant to obtain modified aluminum extraction slag powder, mixing the modified aluminum extraction slag powder with solid waste, and then subjecting the mixture to a mineralization reaction to obtain a mineralized product.

[0006] Furthermore, the effective substance of the dopant is a combination of one or more of alkali metal elements or ions, alkaline earth metal elements or ions, rare earth metal elements or ions, and transition metal elements or ions.

[0007] Furthermore, the sources of the alkali metal ions, alkaline earth metal ions, rare earth metal ions, and transition metal ions include, but are not limited to, any one or a combination of several of their oxides, peroxides, carbonates, halides, nitrates, sulfates, perchlorates, hypochlorites, and meta - salts.

[0008] Furthermore, in the doping agent, the radius of the alkali metal ion, alkaline earth metal ion, rare earth metal ion, or transition metal ion is 0.5 - 1.4 Å, selected from 2+ V 4+ V 5+ Cr 2+ Cr 3+ Cr 4+ Mn 2+ Mn 3+ Mn 4+ Co 2+ Co 3+ Co 4+ Ni 2+ Ni 3+ Fe 2+ Fe 3+ Na + K + Mg 2+ Ti 2+ Ti 3+ Ti 4+ Cu + Cu 2+ Zn 2+ Zr 4+ Y 3+ Nb 3+ Nb 4+ Mo 3+ Mo 4 + Mo 5+ Sn 2+ Sn 4+ at least one of

[0009] Preferably, in the doping agent, the radius of the alkali metal ion, alkaline earth metal ion, rare earth metal ion, or transition metal ion is 0.6 - 1.4 Å, selected from Cr 2+ Cr 3+ Mn 2+ Mn 3+ Co 2+ Ni 2+ Fe 2+ Fe 3+ Na + K + Mg 2+ Ti 2+, Ti 4 + , Cu + , Cu 2+ , Zn 2+ , Zr 4+ , Y 3+ , Nb 3+ , Nb 4+ , Mo 3+ , Mo 4+ , Sn 2+ at least one of the following:

[0010] Furthermore, for the effective substance of the dopant, the standard molar enthalpy of formation of its oxide at 298.15K is 0 to -2000 kJ / mol, preferably -0.1 to -1500 kJ / mol.

[0011] Furthermore, the effective substance of the dopant is V 4+ , V 5+ , Cr 2+ , Cr 3+ , Mn 2+ , Mn 3+ , Ni 2+ , Fe 2+ , Fe 3+ , Na + , K + , Mg 2+ , Ti 2+ , Ti 4+ , Cu + , Cu 2+ , Zn 2+ or at least one or a combination of several of the elemental forms of the above ions.

[0012] Preferably, for the active substance of the dopant, the standard molar enthalpy of formation of its oxide is -240 to -1200 kJ / mol at 298.15K. In this application, the ions of the dopant are used to replace the calcium positions in the crystals of calcium silicate waste (such as tricalcium silicate and dicalcium silicate), improving the mineralization activity of the calcium silicate waste. By optimizing the ionic radius of the active substance of the dopant, the ionic radius of the dopant can better match the crystal radius of the calcium silicate waste in the aluminum extraction slag, forming effective doping and providing appropriate crystal defect sites. However, it is found in this application that when the standard molar enthalpy of formation of the oxide of the active substance of the dopant is further specified to be -240 to -1200 kJ / mol, the modified aluminum extraction slag has a more excellent carbon dioxide fixation effect, and the mechanical strength of the mineralized product is higher. The reason for the analysis is that after the dopant ions are doped, chemical bonds between the dopant ions and oxygen will be generated in the crystals of the modified calcium silicate, which is equivalent to the dopant existing in the crystal lattice of calcium silicate in the form of an oxide. When the standard molar enthalpy of formation of the oxide of the active substance of the dopant is -240 to -1200 kJ / mol, the dopant is more likely to be incorporated into the crystal structure of calcium silicate rather than adhering to the crystal surface of calcium silicate, and further reduces the doping conditions, enabling the doping process to proceed smoothly at a relatively low temperature.

[0013] Further, the active substance of the dopant is V 4+ 、V 5+ 、Cr 3+ 、Ni 2+ 、Fe 2+ 、Fe 3+ 、Na + 、K + 、Mg 2+ 、Ti 4 + 、Zn 2+ or at least one or a combination of several of the elemental substances of the above ions.

[0014] In some preferred embodiments, the active substance of the dopant is Fe 2+ 、Fe 3+ 、Na + 、K + 、Mg 2+ 、Zn 2+ or at least one or a combination of several of the elemental substances of the above ions.

[0015] Further, the dopant accounts for 0.05 - 7% of the mass of the high-temperature aluminum extraction slag, preferably 0.1 - 5%, and more preferably 1 - 3%.

[0016] Further, during the process of mixing and molding the modified aluminum-extracted slag and solid waste, the mass ratio of the modified aluminum-extracted slag, solid waste, and water is (50 - 90):(5 - 40):(3 - 20).

[0017] Further, the solid waste includes, but is not limited to, any one or a combination of several of siliceous solid waste, calcareous solid waste, silicoaluminous solid waste, and silicocalcareous solid waste.

[0018] Further, the sources of the solid waste include, but are not limited to, at least one of smelting slag, furnace slag, coal gangue, tailings, gypsum, desulfurized gypsum, sludge, red mud, fly ash, waste ceramics, and waste refractory materials.

[0019] Further, the method for resource utilization of fly ash aluminum-extracted slag solid waste specifically includes:

[0020] (1) Extracting aluminum by the alkali-lime sintering method: Mixing fly ash, limestone, and soda ash in a mass ratio of (60 - 80):(20 - 35):(5 - 15) for sintering to obtain sodium aluminate, high-temperature aluminum-extracted slag, and flue gas containing CO2;

[0021] (2) Adding a dopant to the high-temperature aluminum-extracted slag, stirring and mixing, cooling, and then crushing and grinding to obtain modified aluminum-extracted slag powder;

[0022] (3) Mixing the modified aluminum-extracted slag powder, solid waste, and water, stirring, and then pressing into a mold;

[0023] (4) Feeding the molded material into a reaction kettle, introducing a gas containing CO2, and carrying out a mineralization reaction under a certain reaction pressure; after the reaction is completed, cooling down and taking out to obtain a mineralized product.

[0024] Further, in the step (1), the mass ratio of fly ash, limestone, and soda ash is (60 - 70):(20 - 30):(5 - 10).

[0025] Further, in the step (1), the sintering temperature is 1100 - 1400 °C, and the sintering time is 40 - 60 min.

[0026] Further, in the step (1), adding lime milk and CO2 to the separated sodium aluminate for reaction to precipitate Al(OH)3, and Al(OH)3 is calcined at high temperature to obtain Al2O3, completing the aluminum extraction process.

[0027] Further, in the step (2), doping and modifying the high-temperature aluminum-extracted slag by using its residual heat, and the residual heat of the aluminum-extracted slag is 900 - 1300 °C, preferably 1000 - 1200 °C.

[0028] Further, in the step (2), the cooling method includes, but is not limited to, any one or a combination of several of natural cooling in a high-temperature furnace, natural cooling in air, and cooling by blowing cold air in air.

[0029] Preferably, the cooling in the step (2) is as follows: first, cool the high-temperature furnace to 600-800 °C, keep the aluminum-extracted slag stay in the furnace for 0.5-3 h, and then take it out and cool it in air.

[0030] Further, after cooling in the step (2), crush the modified aluminum-extracted slag to make its particle size less than 70 mesh.

[0031] Further, in the step (3), the molding pressure is 4.5-45 MPa.

[0032] Further, in the step (4), the filling ratio of the reaction kettle (i.e., the ratio of the total volume of the green compact to the inner space of the reaction kettle) is 5-60%.

[0033] Further, in the step (4), the mineralization reaction pressure is 0.1-3 MPa, preferably 0.15-1.5 MPa; the mineralization reaction time is 2.5-7.5 h.

[0034] Further, in the CO2-containing gas, the volume fraction of CO2 is 8-99%; the CO2-containing gas includes, but is not limited to, at least one of commercially available CO2 gas, the CO2-containing flue gas obtained in the step (1), the flue gas from an aluminum smelter, the flue gas from a coal-fired power plant, the flue gas from a waste incineration plant, the flue gas from a lime kiln, the flue gas from a steel plant, the flue gas from a chemical plant, the flue gas from a cement plant, or the flue gas after carbon capture.

[0035] Further, the method of the present application can be used for the simultaneous resource utilization of fly ash aluminum-extracted slag solid waste and CO2 flue gas.

[0036] Beneficial effects

[0037] 1. The present application provides a method for mineralization utilization of solid waste in the coal chemical industry. This method adopts the ion doping coupling mineralization technology, and realizes the resource utilization of a large amount of solid waste aluminum-extracted slag and waste gas CO2 simultaneously during the process of extracting aluminum from fly ash; at the same time, the present application uses the high temperature of the alkali-lime sintering method for aluminum extraction to conduct ion doping on the aluminum-extracted slag, effectively utilizing the energy in the process and saving energy consumption.

[0038] 2. Modify the aluminum-extracted slag crystals through ion doping, accelerating the change of the micro-structure of the crystals in the aluminum-extracted slag, enhancing its mineralization reaction activity, further improving the strength of the mineralized product and the carbon sequestration performance. By regulating the doping amount of the ion dopant and the ratio of different elements, the selection and regulation of the reaction are realized, the maximum value of the crystal active sites and the maximum doping efficiency are achieved, and then the mineralized building materials with the highest carbon sequestration rate and strength index are obtained;

[0039] 3. By regulating process conditions such as the calcination temperature, calcination time, silicon-calcium ratio, and cooling method, the present invention promotes the phase transformation of the ion-doped fly ash aluminum-extracted slag to achieve self-pulverization, avoiding the long-time grinding process of the aluminum-extracted slag in the conventional technology and reducing the large amount of electric energy consumed for grinding the waste slag in the mineralization stage. Detailed implementation mode

[0040] Example

[0041] The embodiment of this application uses the sintered fly ash from a certain coal plant, and the composition of the fly ash is detected by X-ray fluorescence (XRF), as shown in Table 1 specifically;

[0042] Example 1

[0043] This embodiment provides a method for the resource utilization of fly ash aluminum-extracted slag solid waste, which specifically includes:

[0044] (1) Extracting aluminum by the alkali-lime sintering method: Mix fly ash, limestone, and soda ash in a mass ratio of 65:25:10 (the total mass is recorded as 100 parts), and sinter at 1300 °C for 50 min; obtain sodium aluminate, high-temperature aluminum-extracted slag (specific composition is shown in Table 2), and flue gas containing CO2;

[0045] (2) Separate and remove sodium aluminate, add ZnCO3 (dopant) accounting for 2% of the mass of the high-temperature aluminum-extracted slag to the high-temperature aluminum-extracted slag at 1100 °C, stir and mix, and carry out the modification process;

[0046] After the modification is completed, cool the high-temperature furnace to 700 °C, keep the aluminum-extracted slag in the furnace for 1 h, then take it out and pour it on the open space to cool. After cooling, crush and grind it so that the particles can pass through a 70-mesh sieve to obtain the modified aluminum-extracted slag powder;

[0047] (3) Mix and stir the modified aluminum-extracted slag powder, solid waste, and water in a mass ratio of 75:15:10, and put the mixture into a molding system to press and form at 11.5 MPa;

[0048] (4) Feed the formed material into the reaction kettle. The filling ratio of the reaction kettle (i.e., the ratio of the total volume of the green compact to the internal space of the reaction kettle) is 45%. Feed the gas containing CO2 (specific composition is shown in Table 3) to keep the pressure in the kettle at 0.5 MPa for mineralization. After reacting for 4 h, discharge the flue gas in the kettle to atmospheric pressure, and take out the product after the temperature in the kettle drops below 80 °C.

[0049] Example 2

[0050] This example provides a method for the resource utilization of fly ash aluminum extraction slag solid waste, which specifically includes:

[0051] (1) Extract aluminum by the alkali-lime sintering method: Mix fly ash, limestone, and soda ash in a mass ratio of 65:25:10 (the total mass is recorded as 100 parts), and sinter at 1100 °C for 60 min; obtain sodium aluminate, high-temperature aluminum extraction slag, and flue gas containing CO2.

[0052] (2) Separate and remove sodium aluminate. Add Fe2(CO3)3 accounting for 1% of the mass of the high-temperature aluminum extraction slag to the high-temperature aluminum extraction slag at 1000 °C, stir and mix, and carry out the modification process.

[0053] After the modification is completed, cool the high-temperature furnace to 800 °C, keep the aluminum extraction slag in the furnace for 3 h, then take it out and pour it on the open space to cool. After cooling, crush and grind it so that the particles can pass through a 70-mesh sieve to obtain the modified aluminum extraction slag powder.

[0054] (3) Mix and stir the modified aluminum extraction slag powder, solid waste, and water in a mass ratio of 50:35:15, and put the mixture into the forming system to press and form at 5 MPa.

[0055] (4) Feed the formed material into the reaction kettle. The filling ratio of the reaction kettle (i.e., the ratio of the total volume of the green compact to the internal space of the reaction kettle) is 60%. Feed the gas containing CO2 (specific composition is shown in Table 3) to keep the pressure in the kettle at 0.2 MPa for mineralization. After reacting for 7.5 h, discharge the flue gas in the kettle to atmospheric pressure, and take out the product after the temperature in the kettle drops below 80 °C.

[0056] Example 3

[0057] This example provides a method for the resource utilization of fly ash aluminum extraction slag solid waste, which specifically includes:

[0058] (1) Extract aluminum by the alkali-lime sintering method: Mix fly ash, limestone, and soda ash in a mass ratio of 60:30:10 (the total mass is recorded as 100 parts), and sinter at 1400 °C for 40 min; obtain sodium aluminate, high-temperature aluminum extraction slag, and flue gas containing CO2.

[0059] (2) Separating and removing sodium aluminate, adding ZnCO3 accounting for 4% of the mass of the high-temperature aluminum-extracting slag at 1200 °C, stirring and mixing, and carrying out the modification process;

[0060] After the modification is completed, cool the high-temperature furnace to 600 °C, keep the aluminum-extracting slag in the furnace for 2 h, then take it out and pour it on the open space for cooling. After cooling, crush and grind it so that the particles can pass through a 70-mesh sieve to obtain the modified aluminum-extracting slag powder;

[0061] (3) Mix and stir the modified aluminum-extracting slag powder, solid waste and water according to the mass ratio of 90:5:5, and put the mixture into the molding system to press and form at 25 MPa;

[0062] (4) Feed the formed material into the reaction kettle. The filling ratio of the reaction kettle (that is, the ratio of the total volume of the billet to the inner space of the reaction kettle) is 5%. Pass the gas containing CO2 (the specific composition is shown in Table 3) to keep the pressure in the kettle at 0.8 MPa for mineralization. After reacting for 2.5 h, discharge the flue gas in the kettle to normal pressure, and take out the product after the temperature in the kettle drops below 80 °C.

[0063] Example 4

[0064] It is basically the same as Example 1, except that the addition amount of ZnCO3 accounts for 0.5% of the mass of the high-temperature aluminum-extracting slag.

[0065] Example 5

[0066] It is basically the same as Example 1, except that the addition amount of ZnCO3 accounts for 1% of the mass of the high-temperature aluminum-extracting slag.

[0067] Example 6

[0068] It is basically the same as Example 1, except that the addition amount of ZnCO3 accounts for 3% of the mass of the high-temperature aluminum-extracting slag.

[0069] Example 7

[0070] It is basically the same as Example 1, except that the addition amount of ZnCO3 accounts for 5% of the mass of the high-temperature aluminum-extracting slag.

[0071] Example 8

[0072] It is basically the same as Example 1, except that the addition amount of ZnCO3 accounts for 7% of the mass of the high-temperature aluminum-extracting slag.

[0073] Example 9

[0074] It is basically the same as Example 1, except that the dopant is Na2CO3.

[0075] Example 10

[0076] It is basically the same as Example 1, except that the dopant is K2CO3.

[0077] Example 11

[0078] It is basically the same as Example 1, except that the dopant is MgCO3.

[0079] Example 12

[0080] It is basically the same as Example 1, except that the dopant is CuCO3.

[0081] Example 13

[0082] It is basically the same as Example 1, except that after the modification in step (2), the aluminum-extracted slag is directly taken out and naturally cooled in the air.

[0083] Example 14

[0084] It is basically the same as Example 1, except that after the modification in step (2), the aluminum-extracted slag is naturally cooled in the furnace.

[0085] Example 15

[0086] It is basically the same as Example 1, except that in step (1), the mass ratio of fly ash, limestone and soda ash is 70:20:10 (the total mass is recorded as 100 parts).

[0087] Example 16

[0088] It is basically the same as Example 1, except that the mineralization pressure is 1.2 MPa.

[0089] Example 17

[0090] It is basically the same as Example 1, except that after the modification in step (2), the high-temperature furnace is cooled to 400 °C, the aluminum-extracted slag stays in the furnace for 1 h, and then it is taken out and poured onto an open space to cool.

[0091] Example 18

[0092] It is basically the same as Example 1, except that the molding pressure is 35 MPa.

[0093] Example 19

[0094] It is basically the same as Example 1, except that the molding pressure is 45 MPa.

[0095] Comparative Example 1

[0096] It is basically the same as Example 1, except that in step (1), the mass ratio of fly ash, limestone and soda ash is 75:15:10 (the total mass is recorded as 100 parts).

[0097] Comparative Example 2

[0098] It is basically the same as Example 1, except that: in step (2), no dopant is added.

[0099] Comparative Example 3

[0100] It is basically the same as Example 1, except that: the dopant is boric acid.

[0101] Performance test method:

[0102] The self-pulverization rate is the percentage of particles with a particle size less than 0.01 mm in the total weight of the waste residue of ion-doped fly ash for alumina extraction; the carbon dioxide absorption rate is the percentage of the mass of carbon dioxide absorbed by the solid waste in the mass of the mineralized product, where the content of carbon dioxide absorbed by the solid waste is obtained by testing the TG / DTG curve of the mineralized product, and the content of carbon dioxide absorbed by the solid waste is the weight reduction in the range of 550 - 850 °C; the mass of the mineralized product is the mass of the mineralized product at 105 °C; the compressive strength is carried out according to the standard of GBT4111-2013 "Test Methods for Concrete Blocks and Bricks".

[0103] Performance test results:

[0104] The test results are shown in Table 4.

[0105]

[0106]

[0107]

[0108] Result analysis:

[0109] The products prepared in Examples 1 - 3 have relatively high carbon dioxide absorption rate, compressive strength and self-pulverization rate, indicating that the products prepared by the technical solution of the present application have good self-pulverization effect, significantly reduce the grinding energy consumption, and at the same time, can effectively absorb carbon dioxide, and can obtain relatively high compressive strength after mineralization, meeting the use requirements.

[0110] Comparing Comparative Example 1 with Examples 4-8 and Comparative Example 2, it can be seen that within a certain range, as the dopant content increases, the carbon fixation rate, compressive strength, and pulverization rate of the product all increase. However, when the dopant content exceeds 5% of the mass of the aluminum-extracted slag, the compressive strength of the product decreases, and there is a negative correlation between the product performance and the dopant content. The reason is as follows: When the dosage of the ionic dopant is relatively low, the amount of calcium silicate substituted by zinc ions is relatively low. Therefore, lattice distortion in the modified aluminum-extracted fly ash slag is not likely to occur, the crystal form of calcium silicate is relatively complete, and carbon dioxide is difficult to react completely with it, resulting in relatively low carbon fixation rate and compressive strength of the product. When the dosage of zinc ions is too high, new crystal forms may appear, and carbon dioxide is also not likely to react with it, resulting in lower compressive strength and carbon fixation rate of the product instead.

[0111] Examples 9-12 all showed relatively high carbon fixation rate and compressive strength, meeting the production requirements. This indicates that the radii of the above-mentioned several ions have good matching with the lattice radius of calcium silicate. They exchange ions with calcium silicate in the molten state, resulting in corresponding lattice distortion, making it easier for carbon dioxide to react with calcium silicate at the distortion site during the reaction, and the overall compressive strength and carbon fixation rate of the product increase. Among them, the performance of Example 12 is relatively low, probably because the standard molar enthalpy of formation of copper ion oxide is relatively high, and its oxidation state is not easily doped in the calcium silicate lattice, with low doping efficiency, resulting in a decrease in both the carbon fixation rate and strength of the product, and the self-pulverization rate of the product is also relatively low.

[0112] Examples 13, 14, and 17 regulated the cooling method of the ion-doped aluminum-extracted fly ash slag, directly taking it out for cooling, natural cooling in the furnace, and taking it out after the furnace temperature drops to 400 °C and cooling for one hour. The self-pulverization rate and compressive strength of these three cooling methods are all at a relatively low level. When the slag is taken out for natural cooling after staying at 700 °C for 1 h, this method is more conducive to the phase transformation of calcium silicate, and more β-C2S is transformed into γ-C2S. The phase transformation process is accompanied by volume expansion, resulting in an increase in the self-pulverization rate of the product. At the same time, in the mineralization reaction section, the carbon absorption capacity of β-C2S and γ-C2S and the contribution ability of the reaction products to the strength of the product are different, resulting in the compressive strength of Examples 13, 14, and 17 being much lower than that of Example 1, while the carbon fixation rate is higher than that of Example 1.

[0113] The carbon sequestration rate and compressive strength of the product in Example 15 are relatively low. This is because in step (1), the calcium addition amount is low, resulting in a low content of mineralizable calcium (such as dicalcium silicate) in the modified fly ash alumina extraction residue, leading to a low degree of mineralization and relatively poor overall performance of the product. At the same time, since the essence of the self-pulverization of silicon-calcium slag is the phase change of dicalcium silicate (i.e., β-C2S→γ-C2S transformation), the self-pulverization effect is worse when the calcium content is lower, which may be the reason why the self-pulverization rate in Example 15 is lower than that in Examples 1-3; through the experimental results of Comparative Example 1, this difference is more obvious.

[0114] In Example 16, the pressure of the mineralization reaction was regulated. Comparing with Examples 1-3, it can be seen that when the mineralization pressure is too high, the compressive strength of the product decreases. This may be because the too high mineralization pressure makes the rate of the mineralization reaction too fast in the initial stage. The mineralization reaction occurs first on the surface of the material, closing the microporous structure on the surface of calcium silicate, and carbon dioxide cannot enter the interior of the crystal phase, rendering the active sites inside ineffective, resulting in a decrease in the carbon sequestration rate, compressive strength, and pulverization rate.

[0115] In Examples 18-19, the forming pressure of the material was regulated. It can be seen that when the forming pressure is too high, the volume of the material is compressed to a greater extent, and the pores in the material are significantly reduced, resulting in carbon dioxide being unable to penetrate into the interior of the material, leading to incomplete mineralization inside the material, and thus the carbon sequestration rate and compressive strength of the product decrease instead.

[0116] The dopant used in Comparative Example 3 is boric acid, but the carbon sequestration rate, compressive strength, and self-pulverization rate of its product are all relatively low. This may be because: the radius of the boron ion is relatively small, and when doping in the calcium silicate lattice, it cannot form effective lattice defects or the crystal phase structure has changed. There are few effective carbon dioxide adsorption sites in the modified alumina extraction residue, which is not conducive to the fixation of carbon dioxide, and the mechanical strength of the product also decreases.

Claims

1. A method for the mineralization utilization of solid waste in the coal chemical industry, characterized in that, The method includes: modifying the fly ash high-temperature aluminum extraction slag with a dopant to obtain a modified aluminum extraction slag powder, and mixing and molding the modified aluminum extraction slag powder with solid waste and then carrying out a mineralization reaction to obtain a mineralized product; The effective substance of the dopant is one or a combination of more of an alkali metal element or ion, an alkaline earth metal element or ion, a rare earth metal element or ion, and a transition metal element or ion; The method specifically includes: (1) Aluminum extraction by the soda-lime sintering method: mixing fly ash, limestone, and soda ash in a mass ratio of (60 - 80):(20 - 35):(5 - 15), sintering to obtain sodium aluminate, high-temperature aluminum extraction slag, and flue gas containing CO2; (2) Adding a dopant to the high-temperature aluminum extraction slag, stirring and mixing, cooling, and then crushing and grinding to obtain a modified aluminum extraction slag powder; (3) Mixing, stirring, and pressing the modified aluminum extraction slag powder, solid waste, and water into a mold; (4) Feeding the molded material into a reaction kettle, introducing a gas containing CO2, and carrying out a mineralization reaction under a certain reaction pressure; after the reaction is completed, cooling and taking out to obtain a mineralized product; In step (2), when adding the dopant, the temperature of the high-temperature aluminum extraction slag is 900°C - 1300°C; the cooling process is: first cooling the high-temperature furnace to 600 - 800°C, keeping the aluminum extraction slag in the furnace for 0.5 - 3 h, and then taking it out and cooling it in the air.

2. The method according to claim 1, characterized in that The radius of the alkali metal ion, alkaline earth metal ion, rare earth metal ion or transition metal ion is 0.5-1.4 angstroms and is selected from V 2+ 、V 4+ 、V 5+ Cr 2+ Cr 3+ Cr 4+ , Mn 2+ , Mn 3+ , Mn 4+ 、Co 2+ 、Co 3+ 、Co 4+ 、Ni 2+ 、Ni 3+ , Fe 2+ , Fe 3+ 、Na + , K + Mg 2+ 、Ti 2+ 、Ti 3+ 、Ti 4+ , Cu + , Cu 2+ 、Zn 2+ 、Zr 4+ , Y 3+ , Nb 3 + , Nb 4+ 、Mo 3+ 、Mo 4+ 、Mo 5+ Sn 2+ Sn 4+ At least one of .

3. The method according to claim 1, characterized in that, The radius of the alkali metal ion, alkaline earth metal ion, rare earth metal ion or transition metal ion is 0.6-1.4 angstroms, and is selected from Cr 2+ 、Cr 3+ 、Mn 2+ 、Mn 3+ 、Co 2+ 、Ni 2+ 、Fe 2+ 、Fe 3+ 、Na + 、K + 、Mg 2+ 、Ti 2+ 、Ti 4+ 、Cu + 、Cu 2+ 、Zn 2+ 、Zr 4+ 、Y 3+ 、Nb 3+ 、Nb 4+ 、Mo 3+ 、Mo 4+ 、Sn 2+ and at least one of them.

4. The method according to claim 1, characterized in that The effective substance of the dopant has a standard molar formation enthalpy of its oxide of 0 to -2000 kJ / mol at 298.15 K.

5. The method according to claim 1, characterized in that The effective substance of the dopant has a standard molar formation enthalpy of its oxide of -0.1 to -1500 kJ / mol at 298.15 K.

6. The method according to claim 1, characterized in that The active substance of the dopant is V 4+ 、V 5+ 、Cr 2+ 、Cr 3 + 、Mn 2+ 、Mn 3+ 、Ni 2+ 、Fe 2+ 、Fe 3+ 、Na + 、K + 、Mg 2+ 、Ti 2+ 、Ti 4+ 、Cu + 、Cu 2+ 、Zn 2+ or at least one of the elemental substances of the above ions.

7. The method according to claim 1, wherein The effective substance of the dopant has a standard molar formation enthalpy of its oxide of -240 to -1200 kJ / mol at 298.15 K, and the effective substance of the dopant is V 4+ 、V 5+ 、Cr 3+ 、Ni 2+ 、Fe 2+ 、Fe 3+ 、Na + 、K + 、Mg 2+ 、Ti 4+ 、Zn 2+ or at least one of the elemental substances of the above ions.

8. The method according to claim 1, wherein The active substance of the dopant is Fe 2+ , Fe 3+ , Na + , K + , Mg 2+ , Zn 2+ or at least one of the elemental substances of the above ions.

9. The method according to claim 1, wherein The dopant accounts for 0.05 - 7% of the mass of the high-temperature aluminum extraction slag.

10. The method according to claim 1, wherein The dopant accounts for 0.1 - 5% of the mass of the high-temperature aluminum extraction slag.

11. Application of the method according to any one of claims 1 - 10 in the simultaneous resource utilization of solid waste and CO2 flue gas in the coal chemical industry.

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