Preparation method for reinforcing ardealite consolidated body functional material by using CO2 mineralization

Abstract

The invention provides a preparation method of a functional material for reinforcing ardealite consolidated body by using CO2 mineralization, which comprises the following steps: a CO2 mineralization reaction stage: mixing ardealite and water to form slurry, adding a magnesium ion solution to obtain turbid liquid, adding a composite mineralization enhancer, and introducing CO2 gas at 20-80 DEG C for mineralization reaction for 10-60 minutes to obtain ardealite mineralized slurry; and a large-dosage ardealite consolidated body preparation stage: mixing the ardealite mineralized slurry with a cementing material and an interface modifier, adjusting the water content, stirring, forming and curing to obtain the ardealite consolidated body functional material.

Description

Technical Field

[0001] This invention belongs to the field of industrial solid waste resource recycling and CO2 emission reduction technology, specifically relating to a method for preparing functional materials that enhance the properties of phosphogypsum solidified bodies using CO2 gas mineralization technology. Background Technology

[0002] Phosphogypsum is an industrial waste product generated during phosphoric acid production. my country produces approximately 80 million tons of phosphogypsum annually, with accumulated stockpiles exceeding 800 million tons. These large stockpiles not only occupy vast amounts of land but also cause source pollution of soil and water bodies with phosphorus and fluorine. Although the problems of phosphogypsum stockpiling and pollution have been addressed through building material production, agricultural applications, and mine backfilling, large-scale application still faces bottlenecks. Phosphogypsum itself contains a certain amount of unreacted CaSO4·2H2O and impurities, resulting in poor cementitious properties, low strength, and poor water resistance, limiting its large-scale application. Therefore, enhancing the mechanical properties of phosphogypsum and conducting large-scale research and development of functional materials based on phosphogypsum solidification is of great significance for the sustainable development of my country's phosphorus chemical industry.

[0003] CO2 mineralization and sequestration is a promising CCUS (Carbonized Solid Waste) technology. Its principle involves reacting calcium- and magnesium-containing alkaline solid waste with CO2 to generate stable carbonates. This technology can fix CO2 and, more importantly, the generated calcium carbonate crystals can fill material pores, improving the microstructure and thus enhancing the material's mechanical properties and durability. Currently, phosphogypsum is mainly used to mineralize CO2 to produce calcium carbonate whiskers. This method first prepares a high-concentration phosphogypsum-calcium solution, then purifies the CO2 mineralization product. This process is energy-intensive, has a low scale of phosphogypsum disposal, and requires complex front-end treatment of the phosphogypsum, resulting in lower practical application potential compared to alkaline slag. Current research has explored the use of CO2 in cement-based materials or alkaline slag to drive performance improvements through mineralization. However, research on CO2 mineralization for large-volume phosphogypsum consolidations is relatively limited. Traditional phosphogypsum consolidations generally suffer from low early strength and low softening coefficient (poor water resistance), and simple physical pressing or traditional steam curing offers limited performance improvements for phosphogypsum and fails to achieve synergistic carbon reduction benefits.

[0004] Therefore, this invention aims to provide a novel material and preparation method that can simultaneously solve the two major problems of phosphogypsum resource utilization and CO2 emission reduction. Through an optimized CO2 mineralization process, the mechanical properties and durability of the phosphogypsum solidified body are significantly improved, which can provide technical support for the large-scale consumption of phosphogypsum. Summary of the Invention

[0005] The primary objective of this invention is to provide a method for preparing a CO2 mineralized reinforced phosphogypsum solidified material that is high-performance and low-cost. This method is simple, efficient, and can achieve large-scale disposal of phosphogypsum and effective CO2 sequestration.

[0006] The phosphogypsum solidified functional material and its preparation method provided by this invention require the synergistic effect of CO2 gas and composite mineralizer to generate multi-form micro- and nano-carbonates, and finally use mechanical compression to improve the strength and durability of the solidified body. It requires a large amount of phosphogypsum as the core raw material, combined with mineralization reaction and composite cementing system to achieve synergistic effects of solid waste resource utilization and CO2 mineral sequestration. The specific steps are divided into a. CO2 mineralization reaction stage, and b. preparation stage of the large-volume phosphogypsum solidified body.

[0007] a. CO2 mineralization reaction stage (1) Preparation of phosphogypsum slurry: Phosphogypsum is mixed with water to form a slurry, and then magnesium ion solution is added to obtain a suspension. A composite mineralization enhancer is added, and the prepared phosphogypsum slurry is ready for use.

[0008] (2) CO2 mineralization reaction: The prepared phosphogypsum slurry is placed in a reaction environment at a temperature of 20~80℃, and CO2 gas with different flow rates is introduced to carry out the mineralization reaction. The reaction time is controlled at 10~60 minutes.

[0009] (3) Preparation of phosphogypsum mineralization slurry: During the CO2 mineralization reaction, different proportions of interface modifiers are added, and the mixture is continuously stirred to maintain a uniform reaction within 0.5-1 hour. At this time, the phosphogypsum mineralization reaction produces different mineralization products. The slurry is then prepared and ready for use.

[0010] The liquid-to-solid ratio of the phosphogypsum slurry is 1:5 to 1:20, or it is a saturated leachate.

[0011] The amount of the composite mineralizing enhancer added is 1% to 5% of the mass of the phosphogypsum slurry. The composite mineralizing enhancer contains a mixture of ammonium chloride and carbide slag in a mass ratio of 1:1.

[0012] The flow rate of the CO2 gas is 0.2~1.0 L / min.

[0013] b. Preparation stage of high-dosage phosphogypsum solidified body (1) Preparation of solidified composite slurry system: Weigh a suitable phosphogypsum mineralized slurry, add a certain proportion of cementing material to it, and then mix the phosphogypsum solidified composite slurry evenly by adjusting the water content and the ratio between each component. Stir to initially disperse each component; then stir again to ensure that the composite mineralized product is evenly mixed.

[0014] (2) Solidified body molding process: Take a certain amount of solidified composite slurry and press it into shape using a high-pressure molding method or cast it into shape using a grouting process. The molds used for the two methods are different, and the fluidity of the slurry is different. The solidified composite slurry system needs to be customized according to the requirements.

[0015] (3) Curing process of solidified body: Solidified body specimens formed by different molding methods can be cured to a suitable age under certain temperature and humidity. Then, the mechanical properties and microstructure of the solidified body at a certain age are tested.

[0016] The amount of cementitious material added is 10% to 18% of the mass of the phosphogypsum mineralized slurry, and the cementitious material is a slag-steel slag based cementitious material.

[0017] The amount of the interface modifier added is 0.2% to 1.0% of the mass of the phosphogypsum mineralized slurry; the interface modifier is sodium alginate and / or silane coupling agent KH550.

[0018] It also includes a water-reducing agent, the amount of which is 0.05% to 0.1% of the mass of the phosphogypsum mineralized slurry. The water-reducing agent is selected from polycarboxylate water-reducing agents.

[0019] The molding method is high-pressure molding or casting molding; the curing is carried out under standard curing conditions, and the curing period is 3 to 28 days.

[0020] The present invention has the following advantages and beneficial effects: (1) Mild reaction conditions: Each reaction step can be carried out at room temperature, without the need for high temperature and high pressure, and without the release of dangerous gases, thus reducing energy consumption and equipment requirements; (2) Significant synergistic effect: By reducing impurity interference through pretreatment with mineralization enhancers and surface modifiers, CO2 mineralization reaction simultaneously achieves CO2 sequestration and material structure optimization, eliminating the need for recycling and purification, and enhancing the mechanical properties of the solidified body; (3) Ease of operation: The whole process does not require special equipment, and the mixing and molding process is easy to scale up industrially, making it suitable for large-scale production applications.

[0021] This invention addresses the dual technical bottlenecks of "high pollution and low added value" in existing phosphogypsum treatment and "low efficiency and high cost" in CO2 mineralization. It breaks through the limitations of traditional "consolidation followed by mineralization" and "single reagent activation" methods, constructing an integrated technical system of "phosphogypsum activation - directional CO2 mineralization - performance enhancement of the consolidated body." Its core innovation lies in transforming CO2 from an "emission reduction burden" into a "performance enhancer" for phosphogypsum consolidated bodies through "process integration innovation + material synergistic innovation + reaction regulation innovation." The technical innovations are as follows: Technical point 1: Activation before mineralization breaks through the traditional direct mineralization mode. By using a composite mineralization enhancer, the mineralization reactivity of phosphogypsum is activated, thereby increasing the reaction rate and yield.

[0022] Technical point 2: Alkaline activation-interface regulation dual-function enhancement system, which breaks through the limitations of single alkaline activation or single surfactant, and enhances the strength and properties of phosphogypsum solidified body after phosphogypsum mineralization.

[0023] Technical point 3: Crystal morphology orientation control of mineralization reaction. By controlling the crystal morphology of mineralization products through Mg ions, phosphogypsum consolidation with different properties can be formed, which enhances its potential for multi-scenario functional applications. Attached Figure Description

[0024] Figure 1 This is the SEM image of calcium carbonate after crystal form regulation obtained in Example 1 of the present invention.

[0025] Figure 2 This is the microstructure of the phosphogypsum solidified body in Example 7 of the present invention.

[0026] Figure 3 This describes the morphology of the mineralized products in the phosphogypsum solidified body of Example 10 of the present invention.

[0027] Figure 4 These are the XRD patterns of embodiments 6, 8, and 9 of this invention. Detailed Implementation

[0028] The following 11 embodiments further illustrate the key features of the present invention. The method has two important stages, and the embodiments are analyzed and characterized according to the different stages.

[0029] The high-pressure molding method described in this invention is as follows: 200g of the well-stirred solidified composite slurry is weighed and placed into a steel mold. A hydraulic press is used to apply pressure at a rate of 10 MPa / min to the target pressure of 30 MPa, and the pressure is maintained for 5 minutes. Then, the pressure is released, and the molded specimen is ejected from the mold.

[0030] The casting method described in this invention involves pouring a solidified composite slurry with good fluidity (e.g., slump ≥ 180 mm) into a mold of a specific size coated with a release agent. During casting, the slurry is gently vibrated on a vibrating table for 60 seconds to aid in air release and compaction. After casting, the surface is smoothed and allowed to stand at room temperature for 24 hours until it has partially hardened before demolding.

[0031] Example 1 (1) Weigh a certain amount of phosphogypsum and add it to deionized water in a ratio of 1:5. Stir well with a stirrer and add 0.1 mol / L Mg ion solution (Mg ion solution refers to magnesium sulfate solution, which increases the leaching concentration of phosphogypsum and thus improves the mineralization efficiency).

[0032] (2) Adjust the temperature of the heat-collecting constant temperature heating magnetic stirrer to 20 °C, add 1% composite mineralization enhancer (including ammonium chloride and carbide slag mixed in a mass ratio of 1:1) to the suspension in step (1) during this process, put it into the heat collector and introduce CO2 at a rate of 0.2 L / min under magnetic stirring, and react for 10 min.

[0033] (3) Weigh a quantitative amount of the mineralization reaction slurry and filter it to quantitatively analyze the products of the mineralization reaction. The remaining mineralization reaction slurry is reserved for later use in the preparation process of the solidified body in Example 6.

[0034] Example 2 (1) Weigh a certain amount of phosphogypsum and add it to deionized water at a ratio of 1:10. Stir well with a stirrer and add 0.2 mol / L Mg ion solution (Mg ion solution refers to magnesium sulfate solution, which increases the leaching concentration of phosphogypsum and thus improves the mineralization efficiency).

[0035] (2) Adjust the temperature of the heat-collecting constant temperature heating magnetic stirrer to 40 ℃, add 2% composite mineralization enhancer (including ammonium chloride and carbide slag mixed in a mass ratio of 1:1) to the suspension in step (1) during this process, put it into the heat collector and introduce CO2 at a rate of 0.5 L / min under magnetic stirring, and react for 20 min.

[0036] (3) The slurry after the mineralization reaction was filtered and the products of the mineralization reaction were quantitatively analyzed. The remaining mineralized slurry was kept for later use in the preparation process of the solidified body in Example 7.

[0037] Example 3 (1) Weigh a certain amount of phosphogypsum and add it to deionized water at a ratio of 1:15. Stir well with a stirrer and add 0.1 mol / L Mg ion solution (Mg ion solution refers to magnesium sulfate solution, which increases the leaching concentration of phosphogypsum and thus improves the mineralization efficiency).

[0038] (2) Adjust the temperature of the heat-collecting constant temperature magnetic stirrer to 60 °C, add 3% composite mineralization enhancer (including a mixture of ammonium chloride and carbide slag in a mass ratio of 1:1) to the suspension in step (1) during this process, put it into the heat collector and introduce CO2 at a rate of 0.4 L / min under magnetic stirring, and react for 10 min.

[0039] (3) The slurry after the mineralization reaction was filtered and the products of the mineralization reaction were quantitatively analyzed. The remaining mineralized slurry was kept for later use in the preparation process of the solidified body in Example 8.

[0040] Example 4 (1) Weigh a certain amount of phosphogypsum and add it to deionized water at a ratio of 1:20. Stir with a stirrer to mix thoroughly and add 0.2 mol / L Mg ion solution (Mg ion solution refers to magnesium sulfate solution, which increases the leaching concentration of phosphogypsum and thus improves the mineralization efficiency).

[0041] (2) Adjust the temperature of the heat-collecting constant temperature magnetic stirrer to 80 °C, add 4% composite mineralization enhancer (including ammonium chloride and carbide slag mixed in a mass ratio of 1:1) to the suspension in step (1) during this process, put it into the heat collector and introduce CO2 at a rate of 0.8 L / min under magnetic stirring, and react for 40 min.

[0042] (3) The slurry after the mineralization reaction was filtered and the products of the mineralization reaction were quantitatively analyzed. The remaining mineralized slurry was kept for later use in the preparation process of the solidified body in Example 9.

[0043] Example 5 (1) Weigh a certain amount of phosphogypsum and add it to deionized water at a ratio of 1:20. Stir with a stirrer to mix thoroughly and use a certain amount of saturated supernatant.

[0044] (2) Adjust the temperature of the heat-collecting constant temperature magnetic stirrer to 20 °C, add 5% composite mineralization enhancer (including ammonium chloride and carbide slag mixed in a mass ratio of 1:1) to the suspension in step (1) during this process, put it into the heat collector and introduce CO2 at a rate of 1.0 L / min under magnetic stirring, and react for 60 min.

[0045] (3) The slurry after the mineralization reaction was filtered and the products of the mineralization reaction were quantitatively analyzed. The remaining mineralized slurry was kept for later use in the preparation process of the solidified body in Example 10.

[0046] Example 6 (1) Take a quantitative amount of mineralization reaction slurry from Example 1, add 82% of phosphogypsum and 18% of cementing material (the cementing material is slag-steel slag based cementing material) to it, adjust the water content to 15%, add 0.2 wt% of interface modifier (sodium alginate and silane coupling agent KH550 are each 0.1 wt%), and mix evenly to prepare the phosphogypsum solidified composite slurry.

[0047] (2) Take a certain amount of solidified composite slurry, press it into shape using a high-pressure molding method, press 3 pieces at a time, and remove them from the mold after the appropriate curing period.

[0048] (3) The solidified specimens after demolding can be cured to a suitable age under certain temperature and humidity, and then the mechanical properties and microstructure of the solidified specimens at a certain age are tested.

[0049] Example 7 (1) Take a quantitative amount of the mineralization reaction slurry of Example 2, add 84% of the mass of the mineralization slurry of phosphogypsum and 16% of the cementing material (the cementing material is slag-steel slag based cementing material), adjust the water content to 16%, add 0.4% of the interface modifier (sodium alginate and silane coupling agent KH550 each of 0.1 wt%), and 0.05% of the water-reducing agent (polycarboxylate water-reducing agent), and mix evenly to prepare the phosphogypsum solidified composite slurry.

[0050] (2) Take a certain amount of solidified composite slurry, press it into shape using a high-pressure molding method, press 3 pieces at a time, and remove them from the mold after the appropriate curing period.

[0051] (3) The solidified specimens after demolding can be cured to a suitable age under certain temperature and humidity, and then the mechanical properties and microstructure of the solidified specimens after 28 days are tested.

[0052] Example 8 (1) Take a quantitative amount of mineralized reaction slurry from Example 3, add 86% of phosphogypsum and 14% of cementing material (the cementing material is slag-steel slag based cementing material) to it, adjust the water content to 17%, add 0.6% of interface modifier (sodium alginate and silane coupling agent KH550 each at 0.1 wt%), and 0.1% of water-reducing agent (polycarboxylate water-reducing agent), and mix evenly to prepare a phosphogypsum solidified composite slurry.

[0053] (2) Take a certain amount of solidified composite slurry, press it into shape using a high-pressure molding method, press 3 pieces at a time, and remove them from the mold after the appropriate curing period.

[0054] (3) The solidified specimens after demolding can be cured to a suitable age under certain temperature and humidity, and then the mechanical properties and microstructure of the solidified specimens at a certain age are tested.

[0055] Example 9 (1) Take a quantitative amount of mineralization reaction slurry from Example 4, add 88% of the mass of phosphogypsum and 12% of the cementing material (the cementing material is slag-steel slag based cementing material) to it, adjust the water content to 18%, add 0.8% of the interface modifier (sodium alginate and silane coupling agent KH550 are each 0.1 wt%), and mix evenly to prepare the phosphogypsum solidified composite slurry.

[0056] (2) Take a certain amount of solidified composite slurry, press it into shape using a high-pressure molding method, press 3 pieces at a time, and remove them from the mold after the appropriate curing period.

[0057] (3) The solidified specimens after demolding can be cured to a suitable age under certain temperature and humidity, and then the mechanical properties and microstructure of the solidified specimens at a certain age are tested.

[0058] Example 10 (1) Take a quantitative amount of mineralization reaction slurry from Example 5, add 90% of the mass of phosphogypsum and 10% of the cementing material (the cementing material is slag-steel slag based cementing material) to it, adjust the water content to 15%, add 1.0% of the interface modifier (sodium alginate and silane coupling agent KH550 are each 0.1 wt%), and mix evenly to prepare the phosphogypsum solidified composite slurry.

[0059] (2) Take a certain amount of solidified composite slurry, press it into shape using a high-pressure molding method, press 3 pieces at a time, and remove them from the mold after the appropriate curing period.

[0060] (3) The solidified specimens after demolding can be cured to a suitable age under certain temperature and humidity, and then the mechanical properties and microstructure of the solidified specimens at a certain age are tested.

[0061] Example 11 For the steps of Example 1, without any CO2 mineralization reaction stage, 82% of phosphogypsum and 18% of cementing material (slag-steel slag based cementing material) of the slurry mass are directly added, the moisture content is adjusted to 35%, 0.2% of interface modifier (sodium alginate and silane coupling agent KH550 each at 0.1 wt%) and 0.1% of water-reducing agent (polycarboxylate water-reducing agent) are added, and the phosphogypsum solidified composite slurry is prepared by uniform mixing.

[0062] (2) Take a certain amount of solidified composite slurry, cast it into shape, and remove it from the mold after a suitable curing period.

[0063] (3) The solidified specimens after demolding can be cured to a suitable age under certain temperature and humidity, and then the mechanical properties and microstructure of the solidified specimens at a certain age are tested.

[0064]

[0065] Table 1 Summary of Case Studies on CO2 Capture and Mineralization Using Phosphogypsum Legend Figure 1 This is the SEM image of calcium carbonate after crystal form regulation obtained in Example 1 of the present invention. The reaction of phosphogypsum and CO2 under the regulation of composite mineralization enhancer, the typical morphology of calcium carbonate that may appear in this SEM image is as follows: rhombic crystals and spherical aragonite can be observed under the 500nm scale.

[0066] Figure 2This is the microstructure of the phosphogypsum solidified body in Example 7 of the present invention, wherein the gypsum crystals are short columnar or prismatic, which have a denser structure and mechanical properties. Figure 3 The morphology of the mineralized products in the phosphogypsum solidified body of Example 10 of the present invention is shown. In addition to a large number of gypsum crystals, it also contains a large number of calcium carbonate crystals. These micro- and nano-sized calcium carbonate crystals fill the pore structure of the solidified body and provide better mechanical properties.

[0067] Figure 4 These are the XRD patterns of Examples 6, 8, and 9 of this invention. Through characteristic peak position matching, relative intensity correspondence, and peak shape crystallinity analysis, it is clearly confirmed that calcium carbonate was successfully generated in the samples of Examples 6, 8, and 9 of this invention. This result verifies the effectiveness of the phosphogypsum and CO2 mineralization reaction.

Claims

1. A method for preparing a functional material of phosphogypsum solidified body enhanced by CO2 mineralization, characterized in that, Includes the following steps: (a) CO2 mineralization reaction stage: Phosphogypsum is mixed with water to form a slurry, then magnesium ion solution is added to obtain a suspension, a composite mineralization enhancer is added, and CO2 gas is introduced at 20~80℃ to carry out the mineralization reaction for 10~60 minutes to obtain phosphogypsum mineralization slurry; (b) Preparation stage of high-dosage phosphogypsum solidified body: The phosphogypsum mineralized slurry is mixed with cementitious materials and interface modifiers, the moisture content is adjusted, and after stirring, molding and curing, the phosphogypsum solidified body functional material is obtained.

2. The method as described in claim 1, characterized in that, The liquid-to-solid ratio of the phosphogypsum slurry in step (a) is 1:5 to 1:20, or it is a saturated leachate.

3. The method as described in claim 1, characterized in that, The magnesium ion solution in step (a) includes any one or more combinations of magnesium chloride, magnesium sulfate, and magnesium acetate.

4. The method as described in claim 1, characterized in that, The amount of the composite mineralizing enhancer added in step (a) is 1% to 5% of the mass of the phosphogypsum slurry, and the composite mineralizing enhancer contains a mixture of ammonium chloride and carbide slag.

5. The method as described in claim 4, characterized in that, The flow rate of CO2 gas in step (a) is 0.2~1.0 L / min.

6. The method as described in claim 1, characterized in that, The amount of cementitious material added in step (b) is 10% to 18% of the mass of the phosphogypsum mineralized slurry, and the cementitious material is a slag-steel slag based cementitious material.

7. The method as described in claim 1, characterized in that, The amount of interface modifier added in step (b) is 0.2% to 1.0% of the mass of the phosphogypsum mineralized slurry.

8. The method as described in claim 7, characterized in that, The interface modifier is sodium alginate and / or silane coupling agent KH550.

9. The method as described in claim 1, characterized in that, Step (b) also includes a water-reducing agent, the amount of which is 0.05% to 0.1% of the mass of the phosphogypsum mineralized slurry, and the water-reducing agent is selected from polycarboxylate water-reducing agents.

10. The method as described in claim 1, characterized in that, The molding method described in step (b) is high-pressure molding or casting molding; the curing is carried out under standard curing conditions, and the curing period is 3 to 28 days.

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