Application of amine auxiliary in accelerating carbonization of calcium-based solid waste

Abstract

Specifically, amine compounds such as monoethanolamine (MEA), diethanolamine (DEA), triethanolamine (TEA) and the like are used as catalytic promoters, on one hand, the carbonization rate can be increased, resource utilization can be enhanced, and on the other hand, by accelerating the carbonization process, the calcium-based solid waste carbonization rate can be increased, the calcium-based solid waste carbonization rate can be increased, and the calcium-based solid waste carbonization rate can be increased. Calcium-based solid wastes (carbide slag, steel slag, high-calcium fly ash and the like) can be quickly converted into useful carbonate products (such as calcium carbonate), so that the economic value of the calcium-based solid wastes is improved; on the other hand, environmental pollution can be reduced, and soil and water source pollution possibly caused in the landfill or stacking process is reduced by converting the carbide slag into stable carbonate.

Description

Technical Field

[0001] The present invention relates to the technical field of industrial solid waste resource utilization and carbon capture, and particularly relates to a method and application for accelerating the carbonation of calcium-based solid waste (including carbide slag, steel slag, high-calcium fly ash, etc.) by amine additives. Background Art

[0002] Carbon dioxide capture and storage technology has attracted much attention. Calcium-based solid waste (such as carbide slag, steel slag, high-calcium fly ash) has become the focus of carbon sequestration research due to its high calcium content. Taking carbide slag as an example, its main components are calcium hydroxide (Ca(OH) 2 ) and a small amount of other metal oxides; steel slag contains free calcium oxide (f-CaO) and active components such as calcium silicate; calcium in high-calcium fly ash mostly exists in the form of calcium oxide or calcium silicate. The carbonation treatment of these solid wastes can reduce their volume and at the same time be converted into carbonate products (such as calcium carbonate, etc.), which have wide applications in the fields of building materials, chemical industry, and agriculture. However, the natural carbonation rate of calcium-based solid waste is relatively slow, especially under low carbon dioxide concentration and adverse environmental conditions, resulting in low utilization efficiency.

[0003] At present, existing research has shown that adding certain chemical additives can accelerate the carbonation process of cement and other building materials, but there is still little research on calcium-based solid waste. As a common amino compound, alkanolamine has good hydrophilicity and reactivity and has been applied in many fields, but its application in the carbonation of carbide slag has not been fully studied. Summary of the Invention

[0004] The present invention aims to solve the problem that the natural carbonation rate of calcium-based solid waste is relatively slow, especially under low carbon dioxide concentration and adverse environmental conditions, resulting in low utilization efficiency, and provides an application of amine additives to accelerate the carbonation of calcium-based solid waste.

[0005] In order to achieve the above technical purpose, the technical solution provided by the present invention is:

[0006] Application of amine additives to accelerate the carbonation of calcium-based solid waste.

[0007] Further, the amine additive includes any one of monoethanolamine, diethanolamine, triethanolamine and their derivatives.

[0008] Further, the calcium-based solid waste has a calcium oxide content ≥ 20%, and the calcium-based solid waste includes one or more combinations of carbide slag, steel slag, and high-calcium fly ash.

[0009] Further, the steel slag needs to be pretreated by magnetic separation to remove iron and ground to a specific surface area ≥ 300 m 2 / kg; the high-calcium fly ash needs to be pretreated by water washing to remove carbon.

[0010] Further, the carbonized product is calcium carbonate with a particle size of 0.1 - 10 μm.

[0011] The present invention also provides a method for accelerating the carbonization of calcium-based solid waste with an amine-based additive, comprising the following steps:

[0012] Step 1: Weigh a certain proportion of the amine-based additive, calcium-based solid waste, and water to obtain a mixed sample;

[0013] Step 2: Stir the mixed sample obtained in Step 1 evenly and introduce CO 2 gas flow for carbonization reaction.

[0014] Further, in Step 1, the mass ratio of the amine-based additive to the calcium-based solid waste is not less than 0.003, and the mass ratio of water to the calcium-based solid waste is not less than 1.

[0015] Further, the mass ratio of the amine-based additive to the calcium-based solid waste is 0.0037 - 0.37:1, and the mass ratio of water to the calcium-based solid waste is 10:1.

[0016] Among them, the original concentration of the amine-based additive is 95% - 99%, and the concentration of the prepared amine-based additive is not less than 0.001 mol / L. Preferably, the concentration of the amine-based additive is 0.00625 mol / L - 0.625 mol / L.

[0017] Specifically, deionized water or distilled water is used for water to avoid the influence of impurities.

[0018] Further, in Step 2, the carbonization reaction temperature is 20 - 60 °C, the stirring rate is not less than 150 r / min, and the flow rate of the CO 2 gas flow is not less than 40 ml / min.

[0019] Further, the stirring rate is 150 - 300 r / min, and the flow rate of the CO 2 gas flow is 40 - 160 ml / min.

[0020] Specifically, the CO 2 gas is a high-purity gas (≥95%) to ensure its concentration is suitable for the carbonization reaction.

[0021] The present invention has the following beneficial effects:

[0022] On the one hand, the present invention can improve the carbonization rate and enhance resource utilization. By accelerating the carbonization process, calcium-based solid waste can be converted into useful carbonate products (such as calcium carbonate) more quickly, thereby increasing its economic value. On the other hand, it can reduce environmental pollution. By converting calcium-based solid waste into stable carbonates, the potential soil and water pollution caused by its landfill or stacking is reduced. In summary, the present invention has the following advantages:

[0023] (1) Improve the carbonation rate of calcium-based solid waste and shorten the carbonation time.

[0024] (2) Enhance the resource utilization of calcium-based solid waste and reduce environmental pollution.

[0025] (3) Calcium-based solid waste is converted into useful carbonates through the carbonation process, increasing economic value.

[0026] (4) The products after carbonation have better physical and chemical properties, such as higher stability and better compressive strength. Description of the Drawings

[0027] Figure 1 It is a carbonation rate diagram of the products of the control group and the example group after different reaction times;

[0028] Figure 2 It is the carbonation kinetics fitting of the control group (without adding additives);

[0029] Figure 3 It is the carbonation kinetics fitting of the examples (adding different doses of amine additives);

[0030] Figure 4 It is the thermal analysis data of the product (calcium carbonate);

[0031] Figure 5 It is the morphology of the product of the control group (without adding additives) after reacting for 24 h;

[0032] Figure 6 It is the microscopic morphology of the carbonation product (calcium carbonate) of Example 4;

[0033] Figure 7 It is the phase composition diagram of the carbonation product of Example 1. Detailed Embodiments

[0034] The technical solutions of the present invention will be clearly and completely described below with reference to the drawings. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0035] In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0036] The present invention provides an amine additive for accelerating the carbonation of calcium-based solid waste, including the following steps:

[0037] (1) Material preparation. Weigh 100 grams of dry calcium-based solid waste (such as carbide slag, steel slag or high-calcium fly ash) and put it into a clean stirring container to ensure that the container is pollution-free; weigh the amine-based additive (such as monoethanolamine, diethanolamine or triethanolamine) according to the ratio, dissolve it in distilled water, and prepare additive solutions with concentrations of 0.00625 mol / L, 0.0625 mol / L, 0.125 mol / L, and 0.625 mol / L. Ensure that the additive solution is fully stirred at room temperature until completely dissolved.

[0038] (2) Mixing. Add the additive solution to the calcium-based solid waste and stir evenly under the condition of a stirring rate of 260 r / min to ensure that the additive is evenly distributed in the carbide slag. The mixing time is not less than 10 minutes.

[0039] (3) Carbonization treatment. Transfer the mixture to a closed reaction container, introduce carbon dioxide gas at a specific flow rate (40 - 160 ml / min), and use a gas flowmeter to control the flow rate.

[0040] (4) Sampling and monitoring. Sampling and monitoring. Regularly sample after the reaction starts, and analyze the product characteristics through tests such as pH value, carbonization rate, XRD, FTIR, and SEM.

[0041] Amine-based additives include MEA, DEA, and TEA, which enhance carbonization by modifying the hydration mechanism of carbon dioxide. MEA is a primary amine that nucleophilizes with dissolved carbon dioxide, resulting in the formation of a carbamate intermediate (Equation 1), which is then hydrolyzed to produce HCO 3 - (Equation 2). Further react with Ca(OH) in the system 2 to generate CaCO 3 sequester CO 2 , while the regenerated MEA (Equation 3) promotes the catalytic cycle and significantly increases the carbonization rate. This CO 2 complexation and proton exchange explain the performance after MEA induction, during which its carbonization rate increases by 12.7 times compared to the control.

[0042] CO 2 +2RNH 2 →RNH 3 + +RNHCOO - (1)

[0043] RNHCOO - +H 2 O→RNH 2 +HCO 3 - (2)

[0044] HCO 3- +Ca(OH) 2 +RNH 3 + →CaCO 3 ↓+2H 2 O+RNH 2 (3)

[0045] In contrast, as a secondary amine, DEA forms a carbamic acid intermediate (Equation 4-6). However, due to the steric hindrance of its two hydroxyl groups, the frequency of carbon dioxide collisions is reduced, thereby reducing the efficiency.

[0046]

[0047] R 2 NH 2 + +HCO 3 - +Ca(OH) 2 →CaCO 3 ↓+2H 2 O+R 2 NH(6)

[0048] In contrast, the tertiary amine TEA lacks active hydrogen to directly bind carbon dioxide and may indirectly promote hydration through the polarization effect. However, its large molecular structure and high viscosity hinder the diffusion of carbon dioxide, resulting in a low carbonation rate in the later stage.

[0049]

[0050] HCO 3 - +Ca(OH) 2 +R 3 NH + →CaCO 3 ↓+2H 2 O+R 3 N(8)

[0051] The carbonized product such as calcium carbonate has wide applications in the fields of building materials, chemical engineering, and agriculture. Calcium carbonate can be used in cement, concrete, and soil conditioners. These applications increase the economic value of carbide slag, making it a promising resource.

[0052] The principles and features of the present invention will be described below in conjunction with the embodiments. The examples given are only for explaining the present invention and are not intended to limit the scope of the present invention. For those not specified in the examples, the conventional conditions or the conditions recommended by the manufacturer are followed. For the reagents or instruments not specified for the manufacturer, they are all conventional products that can be obtained through commercial purchase.

[0053] Example 1

[0054] The specific method is as follows: Prepare a monoethanolamine auxiliary agent with a concentration of 0.00625 mol / L, and use distilled water or deionized water. After uniformly mixing the auxiliary agent with the pretreated carbide slag according to a water-solid ratio of 10:1, pour it into a reactor and introduce CO 2 , with a gas flow rate of 40 ml / min, and continuously react for 24 h.

[0055] Example 2

[0056] The specific method is as follows: Prepare a monoethanolamine auxiliary agent with a concentration of 0.0625 mol / L, and use distilled water or deionized water. After uniformly mixing the auxiliary agent with the pretreated carbide slag according to a water-solid ratio of 10:1, pour it into a reactor and introduce CO 2 , with a gas flow rate of 80 ml / min, and continuously react for 24 h.

[0057] Example 3

[0058] The specific method is as follows: Prepare a monoethanolamine auxiliary agent with a concentration of 0.125 mol / L, and use distilled water or deionized water. After uniformly mixing the auxiliary agent with the pretreated carbide slag according to a water-solid ratio of 10:1, pour it into a reactor and introduce CO 2 , with a gas flow rate of 120 ml / min, and continuously react for 24 h.

[0059] Example 4

[0060] The specific method is as follows: Prepare a monoethanolamine auxiliary agent with a concentration of 0.625 mol / L, and use distilled water or deionized water. After uniformly mixing the auxiliary agent with the pretreated carbide slag according to a water-solid ratio of 10:1, pour it into a reactor and introduce CO 2 , with a gas flow rate of 160 ml / min, and continuously react for 24 h.

[0061] Example 5

[0062] The specific method is as follows: Prepare a diethanolamine auxiliary agent with a concentration of 0.125 mol / L, and use distilled water or deionized water. After uniformly mixing the auxiliary agent with the pretreated carbide slag according to a water-solid ratio of 10:1, pour it into a reactor and introduce CO 2 , with a gas flow rate of 40 ml / min, and continuously react for 24 h.

[0063] Example 6

[0064] The specific method is as follows: Prepare a triethanolamine auxiliary agent with a concentration of 0.625 mol / L, and use distilled water or deionized water. After uniformly mixing the auxiliary agent with the pretreated carbide slag according to a water-solid ratio of 10:1, pour it into a reactor and introduce CO 2, the gas flow rate was 40 ml / min, and the continuous reaction lasted for 24 h.

[0065] Example 7

[0066] The specific method was as follows: Prepare a monoethanolamine additive with a concentration of 0.00625 mol / L, using distilled water or deionized water. After uniformly mixing the additive with the pretreated steel slag (CaO > 40%) at a water-to-solid ratio of 10:1, pour it into the reactor and introduce CO 2 , the gas flow rate was 40 ml / min, and the continuous reaction lasted for 24 h.

[0067] Example 8

[0068] The specific method was as follows: Prepare a monoethanolamine additive with a concentration of 0.625 mol / L, using distilled water or deionized water. After uniformly mixing the additive with the pretreated steel slag (CaO > 40%) at a water-to-solid ratio of 10:1, pour it into the reactor and introduce CO 2 , the gas flow rate was 40 ml / min, and the continuous reaction lasted for 24 h.

[0069] Example 9

[0070] The specific method was as follows: Prepare a diethanolamine additive with a concentration of 0.0625 mol / L, using distilled water or deionized water. After uniformly mixing the additive with the pretreated steel slag (CaO > 40%) at a water-to-solid ratio of 10:1, pour it into the reactor and introduce CO 2 , the gas flow rate was 40 ml / min, and the continuous reaction lasted for 24 h.

[0071] Example 10

[0072] The specific method was as follows: Prepare a triethanolamine additive with a concentration of 0.125 mol / L, using distilled water or deionized water. After uniformly mixing the additive with the pretreated steel slag (CaO > 40%) at a water-to-solid ratio of 10:1, pour it into the reactor and introduce CO 2 , the gas flow rate was 40 ml / min, and the continuous reaction lasted for 24 h.

[0073] Example 11

[0074] The specific method was as follows: Prepare a diethanolamine additive with a concentration of 0.0625 mol / L, using distilled water or deionized water. After uniformly mixing the additive with the pretreated high-calcium fly ash (CaO > 25%) at a water-to-solid ratio of 10:1, pour it into the reactor and introduce CO 2 , the gas flow rate was 40 ml / min, and the continuous reaction lasted for 24 h.

[0075] Blank control example 1

[0076] The specific method is as follows: Without adding additives, directly mix water with the pretreated carbide slag in a water-solid ratio of 10:1 evenly, then pour it into the reactor and introduce CO 2 , with a gas flow rate of 40 ml / min, and react continuously for 24 h.

[0077] Blank control example 2

[0078] The specific method is as follows: Without adding additives, directly mix water with the pretreated steel slag in a water-solid ratio of 10:1 evenly, then pour it into the reactor and introduce CO 2 , with a gas flow rate of 40 ml / min, and react continuously for 24 h.

[0079] Its components are summarized in Table 1 and the results are shown in Table 2.

[0080] Table 1 Component table of examples and comparative examples

[0081] Types of additives Types of calcium-based solid wastes m(Additive dosage) / m(Calcium-based solid waste) <![CDATA[CO 2 Gas flow rate ml / min]]> Example 1 Monoethanolamine Calcium carbide slag 0.0037 40 Example 2 Monoethanolamine Calcium carbide slag 0.037 80 Example 3 Monoethanolamine Calcium carbide slag 0.185 120 Example 4 Monoethanolamine Calcium carbide slag 0.37 160 Example 5 Diethanolamine Calcium carbide slag 0.185 40 Example 6 Triethanolamine Calcium carbide slag 0.37 40 Example 7 Monoethanolamine Steel slag 0.0037 40 Example 8 Monoethanolamine Steel slag 0.37 40 Example 9 Diethanolamine Steel slag 0.037 40 Example 10 Triethanolamine Steel slag 0.185 40 Example 11 Diethanolamine High-calcium fly ash 0.037 40 Control Example 1 None Calcium carbide slag 0 40 Control Example 2 None Steel slag 0 40

[0082] Table 2 Data of carbonation rate measured in examples and comparative examples

[0083]

[0084]

[0085] According to Figure 1 , the carbonation process can be divided into four stages, and each stage is regulated by unique mechanisms and additive effects. Induction period (0 - 2 h), acceleration period (2 - 5 h), deceleration period (5 - 10 h), equilibrium period (10 - 24 h).

[0086] Figure 1 Shows the carbonation rate of the products of the control group and the actual example group after different reaction times. The results show that with the increase of the reaction time, the carbonation rate of the sample increases rapidly at first, the growth rate first increases and then decreases, and gradually tends to be flat, and complete carbonation is basically achieved at 24 h. There are differences in the carbonation rates of the samples in different experimental groups, but they are all better than the control group, indicating that monoethanolamine has a significant accelerating effect on the carbonation of carbide slag. And the higher the dosage of monoethanolamine, the better the accelerating effect. However, in the reaction induction period, the accelerating effect of monoethanolamine as an additive is poor, and the accelerating effect is greatly improved after the induction period ends. Among them, monoethanolamine promotes the hydration conversion of CO 2 to form carbamate intermediates to promote CO 2 to HCO 3 - , and then participates in the carbon fixation reaction. Therefore, monoethanolamine will delay the nucleation of calcium carbonate in the reaction induction period, resulting in a smaller early uptake and a significant acceleration in the later stage.

[0087] Table 3 Reaction rate k calculated based on the carbonation kinetics fitting results

[0088] ID k Example 1 0.09±0.02 Example 2 0.16±0.01 Example 3 0.21±0.02 Example 4 0.32±0.04 GC control group 0.01

[0089] As shown in Table 3, the calculated values of the reaction rate k were obtained by further calculating the reaction rate k through the kinetic fitting equations of the control group (without adding monoethanolamine) and the experimental groups (adding different doses of monoethanolamine). Comparing the magnitudes of the k values reflects the magnitudes of the carbonation rates. The results show that the k values of the examples are all greater than those of the control group, indicating that monoethanolamine has the effect of accelerating the carbonation of carbide slag. Further comparing the doses of monoethanolamine, it is found that the higher the dose, the greater the k value and the more obvious the accelerating effect. See Figure 2 the control group, Figure 3 the fitting results of the experimental groups.

[0090] As Figure 4 shown, the TG analysis was presented in the thermal analysis data. After the acceleration of carbonation by monoethanolamine, the thermal stability of the product is higher, the decomposition temperature of the product (calcium carbonate) becomes higher, and the decomposition amount increases in the range of 600 - 850 °C. The enhancement of stability and compressive strength is also reflected in the morphology. According to Figure 5 、 6 comparing the microscopic morphologies of the carbonation products of the control group and the experimental groups, the experimental groups show significant plate-like shapes, better crystallinity, higher strength, and better stability.

[0091] Figure 7 The phase composition of the carbonation product of Example 1 was compared with the standard card of calcium carbonate, and it was confirmed that the main product was calcium carbonate with high crystallinity.

[0092] In summary, the monoethanolamine additive in the present invention has a significant promoting effect during the carbonation process of carbide slag, not only improving the reaction efficiency but also enhancing the quality of the product. Future research can further explore its performance under different reaction conditions and the synergistic effects with other additives to achieve more efficient resource utilization and environmental protection.

[0093] Although the embodiments of the present invention have been shown and described, for those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

[0094] The above specific embodiments are detailed descriptions of the present invention. It cannot be determined that the specific embodiments of the present invention are only limited to these descriptions. For those of ordinary skill in the technical field to which the present invention pertains, without departing from the concept of the present invention, several simple deductions and substitutions can still be made, and all should be regarded as belonging to the protection scope of the present invention.

Claims

1. Application of amine additives to accelerate the carbonization of calcium-based solid waste.

2. The use of the amine auxiliary agent to accelerate the carbonization of calcium-based solid waste according to claim 1, characterized in that: The amine auxiliary agent includes any one of monoethanolamine, diethanolamine, triethanolamine and derivatives thereof.

3. The use of the amine auxiliary agent to accelerate the carbonization of calcium-based solid waste according to claim 1, characterized in that: The calcium oxide content in the calcium-based solid waste is ≥20%, and the calcium-based solid waste includes one or more combinations of carbide slag, steel slag, and high-calcium fly ash.

4. The use of the amine auxiliary agent to accelerate the carbonization of calcium-based solid waste according to claim 3, characterized in that: The steel slag needs to be subjected to magnetic separation to remove iron and then ground to a specific surface area of ​​≥300m 2 / kg pretreatment; the high calcium fly ash needs to be washed and decarbonized.

5. The use of the amine auxiliary agent to accelerate the carbonization of calcium-based solid waste according to claim 1, characterized in that: The carbonization product is calcium carbonate with a particle size of 0.1-10 μm.

6. A method for accelerating the carbonization of calcium-based solid waste using an amine additive, characterized in that: The following steps are involved: Step 1: Weigh a certain proportion of amine additives, calcium-based solid waste and water to obtain a mixed sample; Step 2: Stir the mixed sample described in step 1 evenly and introduce CO2 gas flow to carry out carbonization reaction.

7. The method of accelerating the carbonization of calcium-based solid waste using an amine additive according to claim 6, characterized in that: In step 1, the mass ratio of the amine auxiliary agent to calcium-based solid waste is not less than 0.003, and the mass ratio of water to calcium-based solid waste is not less than 1.

8. The method for accelerating the carbonization of calcium-based solid waste using an amine additive according to claim 7, characterized in that: The mass ratio of the amine auxiliary agent to calcium-based solid waste is 0.0037-0.37:1, and the mass ratio of water to calcium-based solid waste is 10:

1.

9. The method of accelerating the carbonization of calcium-based solid waste using an amine additive according to claim 6, characterized in that: In step 2, the carbonization reaction temperature is 20-60°C, the stirring rate is not less than 150r / min, and the flow rate of CO2 gas flow is not less than 40ml / min.

10. The method for accelerating the carbonization of calcium-based solid waste using an amine additive according to claim 9, characterized in that: The stirring rate is 150-300 r / min, and the flow rate of CO2 gas flow is 40-160 ml / min.

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