Method for strengthening leaching of calcium ions in solid waste by regulating and controlling coordination structure through cooperation of organic alcohol amine and amino acid

Abstract

The invention belongs to the technical field of calcium-containing solid waste resource utilization, and particularly relates to a method for strengthening leaching of calcium ions in solid waste by regulating and controlling a coordination structure through cooperation of organic alcohol amine and amino acid. The method comprises the following steps: mixing the calcium-containing solid waste with a composite leaching agent solution, and leaching to obtain a calcium ion leaching solution; the composite leaching agent solution comprises organic alcohol amine, amino acid and water. According to the invention, an organic alcohol amine-amino acid synergistic coordination structure is innovatively constructed, and a stable calcium complex is spontaneously formed under mild conditions. According to the method, the calcium ion coordination microenvironment is synergistically regulated and controlled through organic alcohol amine-amino acid to achieve efficient leaching of calcium, strong acid or strong alkali pretreatment is not needed, and the energy consumption and equipment corrosion risk are greatly reduced. According to the method, the closed-loop circulation of high-selectivity leaching of calcium ions and in-situ regeneration of the composite leaching agent can be realized, and the method has good application potential.

Description

Technical Field

[0001] This invention belongs to the field of solid waste resource utilization technology, specifically relating to a method for enhancing the leaching of calcium ions from solid waste by utilizing organic alcohol amines in synergistic regulation of amino acid coordination structure. Background Technology

[0002] Large-scale stockpiling of calcium-containing solid waste (such as phosphogypsum, steel slag, carbide slag, and fly ash) will occupy significant amounts of land resources and cause serious damage to the ecological environment. Generally, the generation of calcium-containing solid waste is accompanied by substantial carbon dioxide (CO2) emissions. Therefore, the co-processing of calcium-containing solid waste and CO2 is of great practical significance. Mineralizing CO2 from calcium-containing solid waste is an important development direction for synergistic pollution reduction technologies. Utilizing the conversion of CO2 from calcium-containing solid waste into carbonates holds promise for achieving low-energy, large-scale CO2 sequestration and solid waste resource utilization.

[0003] CO2 mineralization technology for calcium-containing solid waste is mainly divided into direct mineralization and indirect mineralization. Compared with direct mineralization, indirect mineralization technology has significant advantages in terms of mineralization efficiency, product value, and process cost. The core of indirect mineralization technology lies in the calcium ion leaching agent. Traditional calcium ion leaching methods mainly rely on strong acids or strong alkalis, which, although able to dissolve calcium, suffer from problems such as high energy consumption, strong corrosiveness, secondary pollution, and poor selectivity. Therefore, developing a high-efficiency, low-cost calcium ion leaching agent is of great significance for the development of CO2 mineralization technology for calcium-containing solid waste.

[0004] The related technology discloses a method for leaching calcium ions from calcium-containing solid waste, which uses a protonated organic alcohol amine solution to achieve calcium ion leaching. However, this leaching method requires a proton donor (mainly a strong acid such as hydrochloric acid or nitric acid) to protonate the organic alcohol amine, and the calcium ion leaching efficiency is low. Summary of the Invention

[0005] In view of this, the purpose of this invention is to provide a method for enhancing the leaching of calcium ions from solid waste by utilizing organic alcohol amines and amino acids to regulate the coordination structure. In this leaching method, organic alcohol amines and amino acids spontaneously form a stable calcium coordination structure, achieving highly efficient leaching of calcium ions from calcium-containing solid waste without the need for strong acids or alkalis.

[0006] This invention provides a method for enhancing calcium ion leaching from solid waste by utilizing organic alcohol amines in synergistic regulation of amino acid coordination structures, comprising the following steps: Calcium-containing solid waste and a composite leaching agent solution are mixed and leached to obtain a calcium ion leaching solution. The composite extractant solution comprises organic alcohol amines, amino acids, and water.

[0007] Preferably, the organic alcohol amine includes one or more of ethanolamine, diethanolamine, and triethanolamine.

[0008] Preferably, the amino acid includes one or more of glycine, glutamic acid, aspartic acid, and histidine.

[0009] Preferably, the molar ratio of the amino acid to the organic alcohol amine is 1:0.01~0.3.

[0010] Preferably, the total concentration of organic alcohol amines and amino acids in the composite extractant solution is 0.5~2 mol / L.

[0011] Preferably, the ratio of the mass of the calcium-containing solid waste to the volume of the composite leaching agent solution is 0.02~0.06 kg / L.

[0012] Preferably, the immersion temperature is 25~80℃ and the time is 1~60min.

[0013] Preferably, the calcium-containing solid waste includes one or more of steel slag, fly ash, carbide slag, desulfurized gypsum, and phosphogypsum.

[0014] Preferably, after obtaining the calcium ion leaching solution, the method further includes: introducing CO2 gas into the calcium ion leaching solution to carry out a mineralization reaction, separating the solid and liquid, and obtaining calcium carbonate and a regenerated composite leaching agent solution.

[0015] Preferably, the volume concentration of CO2 in the CO2-containing gas is 10% to 99%, and the flow rate of the CO2-containing gas is 10 to 30 L / h.

[0016] Compared with the prior art, the present invention has the following beneficial effects: This invention provides a method for enhancing the leaching of calcium ions from solid waste by utilizing organic alcohol amines in conjunction with amino acids to regulate the coordination structure, comprising the following steps: mixing calcium-containing solid waste with a composite leaching agent solution for leaching to obtain a calcium ion leaching solution; wherein the composite leaching agent solution comprises organic alcohol amines, amino acids and water.

[0017] This invention innovatively utilizes the synergistic effect of organic alcohol amines and amino acids to achieve precise control of the coordination structure of calcium ions in solid waste, thereby significantly improving calcium leaching efficiency and selectivity. First, the coordination number of calcium ions is typically 6-8. Amino acids occupy only 1-2 sites with their carboxyl oxygen (major coordination site) and amino nitrogen (weak coordination site), resulting in insufficient complexation ability for calcium ions. The hydroxyl groups in organic alcohol amines can provide lone pairs of electrons to fill the remaining coordination vacancies of calcium ions, improving the complexation effect and enhancing calcium ion leaching. Second, amino acids ionize their carboxyl groups under alkaline conditions, making them more likely to bind with metal ions; and organic alcohol amines themselves are bases, increasing the pH value and promoting the ionization of amino acids, thus indirectly enhancing their complexation ability. Finally, organic alcohol amines and amino acids indirectly stabilize the calcium ion coordination layer through a hydrogen bond network, further enhancing calcium ion leaching. Example data shows that the method of this invention has a high calcium ion leaching efficiency in solid waste, reaching 96.96%.

[0018] This invention utilizes the synergistic regulatory effect of organic alcohol amines and amino acids on the coordination structure of calcium ions to achieve efficient and selective leaching of calcium ions from solid waste. The leaching method of this invention overcomes the limitations of traditional leaching processes, avoiding the use of large amounts of strong acid (or strong alkali) reagents, thus reducing reagent corrosivity and environmental risks. This invention lays a solid foundation for subsequent high-purity calcium resource recovery and is applicable to a wide range of calcium-containing solid waste types, providing a new, efficient, green, and sustainable approach to calcium recovery. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a schematic diagram of the calcium leaching process for calcium-containing solid waste in the embodiments. Figure 2 This is a schematic diagram of the leaching equipment for calcium ions in calcium-containing solid waste in the embodiment. Figure 3 The results show the leaching efficiency of the recycled composite leaching agent solution in Example 7. Detailed Implementation

[0021] This invention provides a method for enhancing calcium ion leaching from solid waste by utilizing organic alcohol amines in synergistic regulation of amino acid coordination structures, comprising the following steps: Calcium-containing solid waste and a composite leaching agent solution are mixed and leached to obtain a calcium ion leaching solution. The composite extractant solution comprises organic alcohol amines, amino acids, and water.

[0022] Unless otherwise specified, all materials and equipment used in this invention are commercially available products in the field.

[0023] In this invention, the organic alcohol amine preferably includes one or more of ethanolamine, diethanolamine, and triethanolamine.

[0024] In this invention, the amino acid preferably includes one or more of glycine, glutamic acid, aspartic acid and histidine.

[0025] In this invention, the molar ratio of the amino acid to the organic alcohol amine is preferably 1:0.01~0.3, specifically 1:0.05, 1:0.10, 1:0.15, 1:0.20, 1:0.25, or 1:0.3. This molar ratio allows for the stable generation of amino acid species with strong coordination ability within a pH range of 10~12 while maintaining sufficient buffering, thereby improving the Ca2+ level. 2+ The leaching rate and endpoint concentration were improved, and the selectivity for Mg / Fe was enhanced.

[0026] In this invention, the total concentration of organic alcohol amines and amino acids in the composite leaching agent solution is preferably 0.5~2 mol / L, specifically 0.5 mol / L, 0.8 mol / L, 1.0 mol / L, 1.4 mol / L, 1.8 mol / L, or 2.0 mol / L. The concentration range described in this invention can balance pH buffering, complexation pull, ionic strength, and viscosity during the leaching process, achieving efficient and selective Ca2+ extraction. 2+ Leaching.

[0027] This invention utilizes the synergistic regulation of coordination structures by organic alcohol amines and amino acids to enhance the leaching of calcium ions from solid waste. Employing a binary composite system of "organic alcohol amine-amino acid," the synergistic regulation of calcium ion coordination structures by both (coordination relay, microenvironment optimization) enables efficient and highly selective leaching of calcium ions from calcium-containing solid waste under mild conditions. This invention, based on the coordination principle of synergistic regulation, overcomes the limitations of traditional leaching methods, achieving significant improvements in calcium leaching efficiency, selectivity, and environmental friendliness, providing a novel, efficient, and more sustainable solution for the resource utilization of calcium-rich solid waste.

[0028] In this invention, the calcium-containing solid waste preferably includes one or more of steel slag, fly ash, carbide slag, desulfurized phosphogypsum, and phosphogypsum; in a specific embodiment of this invention, the calcium content in the steel slag is 45.10%, the calcium content in the fly ash is 10.35%, the calcium content in the carbide slag is 68.70%, the calcium content in the desulfurized phosphogypsum is 70.45%, and the calcium content in the phosphogypsum is 49.10%.

[0029] In this invention, the calcium-containing solid waste is preferably used in powder form. The calcium-containing solid waste is preferably pretreated before use, and the pretreatment preferably includes ball milling and / or sieving, collecting the undersize portion. The sieve used for sieving is preferably a 100-200 mesh sieve, specifically a 100 mesh sieve, a 150 mesh sieve, a 160 mesh sieve, or a 200 mesh sieve. When the calcium-containing solid waste is carbide slag, it can be directly sieved, collecting the undersize portion.

[0030] In this invention, the ratio of the mass of the calcium-containing solid waste to the volume of the composite leaching agent solution is preferably 0.02~0.06 kg / L, specifically 0.02 kg / L, 0.03 kg / L, 0.04 kg / L, 0.05 kg / L or 0.06 kg / L.

[0031] In this invention, the immersion temperature is preferably 25~80℃, specifically 25℃ (room temperature), 40℃, 50℃, 60℃ or 70℃, and the immersion time is preferably 1~60min, specifically 20min, 30min, 40min, 50min or 60min. The immersion is preferably carried out under stirring, and the stirring rate is preferably 1000rpm.

[0032] In this invention, after obtaining the calcium ion leaching solution, the process preferably further includes: introducing CO2-containing gas into the calcium ion leaching solution to conduct a mineralization reaction, followed by solid-liquid separation to obtain calcium carbonate and a regenerated composite leaching agent solution. The volume concentration of CO2 in the CO2-containing gas is preferably 10%~99%, specifically 50%; the flow rate of the CO2-containing gas is preferably 10~30 L / h, specifically 15 L / h; and, taking 10 L of calcium ion leaching solution as an example, the time for introducing the CO2-containing gas is preferably 30~60 min. The regenerated composite leaching agent solution can be recycled, preferably 1~5 times.

[0033] This invention involves ball milling and sieving calcium-containing solid waste, then adding it to a composite leaching agent solution of organic alcohol amines and amino acids. Utilizing the coordination effect of organic alcohol amines and amino acids on calcium ions, the calcium ions in the calcium-containing solid waste are selectively complexed, achieving efficient and stable leaching of calcium ions. After introducing CO2 gas into the calcium ion leaching solution for a mineralization reaction, solid-liquid separation yields calcium carbonate product and a regenerated composite leaching agent solution, which is then recycled.

[0034] To further illustrate the present invention, the method for enhancing calcium ion leaching from solid waste by utilizing organic alcohol amines in synergistic regulation of coordination structure with amino acids, provided by the present invention, will be described in detail below with reference to the accompanying drawings and embodiments. However, these descriptions should not be construed as limiting the scope of protection of the present invention.

[0035] Figure 1The diagram above illustrates the calcium ion leaching process for calcium-containing solid waste in this embodiment. After pretreatment (ball milling and sieving) of the calcium-containing solid waste, calcium ion leachate is obtained by enhancing leaching with amino acids and organic alcohol amines. CO2 is then introduced for mineralization to obtain calcium carbonate and a regenerated leaching agent solution. The regenerated leaching agent solution can be recycled.

[0036] Figure 2 This is a schematic diagram of the calcium leaching equipment for calcium-containing solid waste in the embodiment. The process uses solid waste as raw material, which is fed into the leaching tank via a feeder. Under the action of the leaching agent, the calcium element in the solid waste is efficiently leached out, and an external circulation system is used to enhance the uniformity of the reaction. The leached slurry is then subjected to solid-liquid separation by a centrifuge, and the resulting calcium-containing solution enters the mineralization tank, where carbon dioxide is introduced to leach the calcium. 2+ The slurry undergoes a mineralization reaction with CO2 to produce calcium carbonate. Subsequently, the slurry is reintroduced into a centrifuge to separate the calcium carbonate solid product and the mother liquor. The mother liquor can be recycled back to the leaching kettle for continued use, thus constructing a closed-loop process of "calcium extraction from solid waste - CO2 mineralization to prepare calcium carbonate".

[0037] Example 1 A method for enhancing calcium ion leaching from solid waste by utilizing organic alcohol amines in synergistic coordination with amino acids to regulate coordination structure includes the following steps: (1) Steel slag is ball-milled and then passed through a 200-mesh sieve to obtain steel slag powder.

[0038] (2) Glycine and triethanolamine were mixed at a molar ratio of 1:0.3 and dissolved in 10 L of deionized water to obtain a composite extractant solution with a total concentration of 1.4 mol / L.

[0039] (3) 0.5±0.01 kg of steel slag powder was added to the composite leaching agent solution and heated continuously for 60 min at a stirring rate of 1000 rpm and a constant temperature of 50℃ to achieve the leaching of calcium ions in the steel slag. After the leaching process was completed, the solid-liquid mixture after the reaction was separated by vacuum filtration to obtain calcium ion leaching solution. The leaching efficiency is shown in Table 1.

[0040] Example 2 A method for enhancing calcium ion leaching from solid waste by utilizing organic alcohol amines in synergistic coordination with amino acids to regulate coordination structure includes the following steps: (1) Pass the carbide slag through a 200-mesh sieve to obtain carbide slag powder.

[0041] (2) Glycine and triethanolamine were mixed at a molar ratio of 1:0.05 and dissolved in 10 L of deionized water to obtain a composite extractant solution with a total concentration of 1.0 mol / L.

[0042] (3) 0.2±0.01 kg of carbide slag powder was added to the composite leaching agent solution. The mixture was heated for 20 min at a stirring rate of 1000 rpm and a constant temperature of 60℃ to achieve the leaching of calcium ions in the carbide slag. After the leaching process was completed, the solid-liquid mixture after the reaction was separated by vacuum filtration to obtain calcium ion leaching solution. The leaching efficiency is shown in Table 1.

[0043] Example 3 A method for enhancing calcium ion leaching from solid waste by utilizing organic alcohol amines in synergistic coordination with amino acids to regulate coordination structure includes the following steps: (1) Pass the carbide slag through a 150-mesh sieve to obtain carbide slag powder.

[0044] (2) Mix aspartic acid and ethanolamine at a molar ratio of 1:0.10 and dissolve them in 10 L of deionized water to obtain a composite extractant solution with a total concentration of 0.5 mol / L.

[0045] (3) 0.3±0.01 kg of carbide slag powder was added to the composite leaching agent solution. The reaction was carried out for 40 min at a stirring rate of 1000 rpm and a constant temperature of 25℃ to achieve the leaching of calcium ions in the carbide slag. After the leaching process was completed, the solid-liquid mixture after the reaction was separated by vacuum filtration to obtain calcium ion leaching solution. The leaching efficiency is shown in Table 1.

[0046] Example 4 A method for enhancing calcium ion leaching from solid waste by utilizing organic alcohol amines in synergistic coordination with amino acids to regulate coordination structure includes the following steps: (1) After ball milling, fly ash is passed through a 100-mesh sieve to obtain fly ash powder.

[0047] (2) Mix glutamic acid and diethanolamine at a molar ratio of 1:0.15 and dissolve them in 10 L of deionized water to obtain a composite extractant solution with a total concentration of 0.8 mol / L.

[0048] (3) 0.6±0.01 kg of fly ash powder was added to the composite leaching agent solution and heated continuously for 20 min at a stirring rate of 1000 rpm and a constant temperature of 70℃ to achieve the leaching of calcium ions in fly ash. After the leaching process was completed, the solid-liquid mixture after the reaction was separated by vacuum filtration to obtain calcium ion leaching solution. The leaching efficiency is shown in Table 1.

[0049] Example 5 A method for enhancing calcium ion leaching from solid waste by utilizing organic alcohol amines in synergistic coordination with amino acids to regulate coordination structure includes the following steps: (1) Phosphogypsum powder is obtained by ball milling and passing through a 150-mesh sieve.

[0050] (2) Mix histidine and ethanolamine in a molar ratio of 1:0.20 and dissolve them in 10 L of deionized water to obtain a composite extractant solution with a total concentration of 1.8 mol / L.

[0051] (3) 0.4±0.01 kg of phosphogypsum powder was added to the composite leaching agent solution. The mixture was heated for 30 min at a stirring rate of 1000 rpm and a constant temperature of 40℃ to achieve the leaching of calcium ions in phosphogypsum. After the leaching process was completed, the solid-liquid mixture after the reaction was separated by vacuum filtration to obtain calcium ion leaching solution. The leaching efficiency is shown in Table 1.

[0052] Example 6 A method for enhancing calcium ion leaching from solid waste by utilizing organic alcohol amines in synergistic coordination with amino acids to regulate coordination structure includes the following steps: (1) After ball milling, the desulfurized phosphogypsum is passed through a 200-mesh sieve to obtain desulfurized phosphogypsum powder.

[0053] (2) Mix histidine and diethanolamine in a molar ratio of 1:0.25 and dissolve them in 10 L of deionized water to obtain a composite extractant solution with a total concentration of 2.0 mol / L.

[0054] (3) 0.2±0.01 kg of desulfurized phosphogypsum powder was added to the composite leaching agent solution. The mixture was heated for 50 min at a stirring rate of 1000 rpm and a constant temperature of 60℃ to achieve the leaching of calcium ions in the desulfurized phosphogypsum. After the leaching process was completed, the solid-liquid mixture after the reaction was separated by vacuum filtration to obtain calcium ion leaching solution. The leaching efficiency is shown in Table 1.

[0055] Comparative Example 1 In Example 2, glycine in the composite leaching agent solution was replaced with citric acid, and the other steps were the same as in Example 2. The leaching efficiency is shown in Table 1.

[0056] Comparative Example 2 In Example 2, glycine in the composite leaching agent solution was replaced with acetic acid, and the other steps were the same as in Example 2. The leaching efficiency is shown in Table 1.

[0057] Comparative Example 3 In Example 2, glycine in the composite leaching agent solution was replaced with hydrochloric acid, and the other steps were the same as in Example 2. The leaching efficiency is shown in Table 1.

[0058] Comparative Example 4 In Example 2, triethanolamine in the composite leaching agent solution was replaced with ammonia, and the other steps were the same as in Example 2. The leaching efficiency is shown in Table 1.

[0059] Comparative Example 5 In Example 2, triethanolamine in the composite leaching agent solution was replaced with sodium hydroxide, and the other steps were the same as in Example 2. The leaching efficiency is shown in Table 1.

[0060] Table 1 Summary of calcium ion leaching efficiency in the examples and comparative examples

[0061] In Comparative Examples 1-3, organic alcohol amines were used with the addition of citric acid, acetic acid, or hydrochloric acid as calcium ion leaching agents; in Comparative Examples 4-5, amino acids were used with the addition of ammonia or sodium hydroxide as calcium ion leaching agents. In Comparative Examples 1-5, leaching was primarily achieved through complexation with calcium ions. While organic alcohol amines (or amino acids) alone can selectively leach calcium ions through complexation, this requires treatment with other acids (or bases). This acid (or base) modification process not only increases reagent consumption and operational complexity but also exacerbates equipment corrosion, increases the risk of co-dissolution of impurity metal ions, and poses significant challenges to subsequent wastewater treatment.

[0062] Example 7 The calcium ion leaching solution obtained in Example 2 was passed through a gas containing 50% CO2 at a flow rate of 15 L / h for a mineralization reaction for 30 min. After the reaction, solid-liquid separation was performed to obtain a regenerated composite leaching agent solution. A total of 5 leaching-mineralization cycles were performed, with leaching efficiency as shown in the figure. Figure 3 As shown.

[0063] Depend on Figure 3 It can be seen that the composite leaching agent solution provided by this invention exhibits good reactivity upon first use, with a leaching rate exceeding 95%. After multiple cycles of use, its leaching rate remains above 80% (leaching rates of 96.96%, 86.27%, 82.84%, 79.66%, and 80.00% for the first to fifth cycles, respectively), indicating that it has good cycle stability and recyclability.

[0064] Although the above embodiments have provided a detailed description of the present invention, they are only some embodiments of the present invention, not all embodiments. People can obtain other embodiments based on the present invention without creative effort, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A method for enhancing calcium ion leaching from solid waste by utilizing organic alcohol amines in synergistic regulation of amino acid coordination structures, characterized in that, Includes the following steps: Calcium-containing solid waste and a composite leaching agent solution are mixed and leached to obtain a calcium ion leaching solution. The composite extractant solution comprises organic alcohol amines, amino acids, and water.

2. The method according to claim 1, characterized in that, The organic alcohol amines include one or more of ethanolamine, diethanolamine, and triethanolamine.

3. The method according to claim 1, characterized in that, The amino acids include one or more of glycine, glutamic acid, aspartic acid, and histidine.

4. The method according to claim 1, characterized in that, The molar ratio of the amino acid to the organic alcohol amine is 1:0.01~0.

3.

5. The method according to claim 1 or 4, characterized in that, The total concentration of organic alcohol amines and amino acids in the composite extractant solution is 0.5~2 mol / L.

6. The method according to claim 5, characterized in that, The ratio of the mass of the calcium-containing solid waste to the volume of the composite leaching agent solution is 0.02~0.06 kg / L.

7. The method according to claim 1, characterized in that, The immersion temperature is 25~80℃, and the time is 1~60min.

8. The method according to claim 1, characterized in that, The calcium-containing solid waste includes one or more of steel slag, fly ash, carbide slag, desulfurized gypsum, and phosphogypsum.

9. The method according to claim 1, characterized in that, After obtaining the calcium ion leaching solution, the process also includes: introducing CO2 gas into the calcium ion leaching solution to carry out a mineralization reaction, separating the solid and liquid phases, and obtaining calcium carbonate and a regenerated composite leaching agent solution.

10. The method according to claim 9, characterized in that, The volume concentration of CO2 in the CO2-containing gas is 10%~99%, and the flow rate of the CO2-containing gas is 10~30 L / h.

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