Method for accelerating mineralization of low-risk solid waste and preparing soil-like substrate using ammonium acetate

Abstract

The application discloses a method for accelerating mineralization of low-risk solid waste and preparing soil-like substrate by using ammonium acetate, which comprises leaching of active calcium components, CO2 carbon mineralization reaction and preparation of soil-like substrate. The whole mineralization process of the application is a mild reaction process at normal temperature and pressure, and the leaching and mineralization process by using ammonium acetate is beneficial to improving the mineralization efficiency and capacity of low-risk solid waste and helping carbon emission reduction. The leaching by using ammonium acetate can enhance the inorganic C and N nutrient content of low-risk solid waste, improve the pH, nutrient content, granule structure and other physical and chemical properties of the low-risk solid waste, improve the water and soil conservation performance of the low-risk solid waste by adding waste diapers, and is beneficial to rapid planting and sustainable growth of plants. The method of the application is simple in operation, safe and reliable, can reduce solid waste storage, improve the resource utilization rate of bulk solid waste, and has significant environmental and social benefits.

Description

Technical Field

[0001] This invention belongs to the field of mineralizer preparation technology, specifically relating to a method for accelerating the mineralization of low-risk solid waste and preparing a soil-like matrix using ammonium acetate. Background Technology

[0002] Low-risk solid wastes such as steel slag, copper slag, and construction waste accumulate in large quantities, making large-scale resource utilization difficult. These low-risk solid wastes contain a large amount of calcium oxide, which is an important pathway to carbon emission reduction in the current context of carbon peaking and carbon neutrality. However, conventional leaching agents suffer from problems such as stringent solid waste mineralization conditions, high costs, difficulty in regeneration, and poor economic benefits. Therefore, finding low-cost, green leaching agents is a key step in significantly improving the mineralization efficiency and capacity of smelting slags.

[0003] While roadbed materials, building materials, ceramics, and microcrystalline glass can absorb some of the low-risk solid waste, market acceptance is low, failing to achieve the ultimate goal of large-scale solid waste disposal. Ecological treatment aims to improve the physicochemical properties of solid waste to support sustainable vegetation growth; however, low-risk solid waste is nutrient-poor and has poor water retention, making it unsuitable for direct ecological treatment.

[0004] In the prior art, patent CN116785890A discloses a carbon capture agent, absorbent, device, capture system, and application based on amino acids. By mixing various amino acids with alkaline solid waste and then introducing CO2, carbon dioxide capture and separation can be achieved, and the amino acids can be regenerated and recycled. However, this patent fails to achieve permanent CO2 fixation, and the cost of amino acids is extremely high, limiting its application scope.

[0005] In the prior art, patent CN117716968A discloses an artificial soil and its preparation method. This method involves preparing hydrothermal carbon from organic solid waste through hydrothermal treatment, and then mixing the extracted soil-biological mixture with urban solid waste to prepare artificial soil, which can also facilitate the large-scale disposal of urban solid waste. However, this patent's hydrothermal treatment of organic solid waste is subject to stringent conditions, high energy consumption, and a long cycle, making it unsuitable for achieving green, efficient, and large-scale disposal of urban solid waste.

[0006] Therefore, it is essential to develop a method that overcomes the shortcomings of existing accelerated mineralization leaching agents for calcium-containing solid waste, such as high cost, long cycle, and poor mineralization effect, and further improves the nutrient content of solid waste by using ammonium acetate to accelerate the mineralization of low-risk solid waste and prepare soil-like matrix. Summary of the Invention

[0007] To address the aforementioned technical problems, the present invention aims to provide a method for accelerating the mineralization of low-risk solid waste and preparing a soil-like matrix using ammonium acetate.

[0008] The objective of this invention is achieved by including the following steps: S1. Leaching of active calcium components: Low-risk solid waste is mixed with ammonium acetate leaching agent, and the mixture is stirred until the supernatant of the solution contains Ca. 2+ The concentration is constant; S2, CO2 carbon mineralization reaction: CO2 gas is introduced into the slurry of step S1 and stirred continuously until the pH of the slurry no longer changes. Then, the CO2 gas supply is stopped, and solid-liquid phase separation is carried out to obtain mineralized solid waste and liquid respectively. S3. Preparation of soil-like matrix: Add waste diaper fragments with a size of 3cm-5cm to the mineralized solid waste obtained in step S2 and mix well. The amount of waste diaper fragments added is 1.5%-3% of the mass of the mineralized solid waste. Spray water into the mixture to adjust the moisture content to 80%-85% to obtain a soil-like matrix. By adding waste diapers, the water retention performance of the mineralized solid waste is improved, in order to provide a new way for accelerating the mineralization of low-risk solid waste and ultimately achieving large-scale green and ecological utilization.

[0009] Preferably, the ammonium acetate leaching agent in step S1 is an ammonium acetate solution of 0.3 mol / L to 1.0 mol / L.

[0010] Preferably, the solid waste from step S1 is mixed with ammonium acetate leaching agent at a liquid-to-solid ratio of 5 to 20:1, and stirred and reacted at 20°C to 80°C for 30 to 60 minutes.

[0011] Preferably, the stirring speed in step S1 is 800 rpm to 1200 rpm.

[0012] Preferably, the supernatant Ca in step S1 2+ The concentration change within 10 minutes was less than 50 mg / L.

[0013] Preferably, the CO2-containing gas in step S2 is high-temperature flue gas from a smelter that has undergone desulfurization, denitrification, and dust removal.

[0014] Preferably, the mineralization reaction is considered to be complete when the pH of the slurry drops to 6.0-7.0 in step S2.

[0015] Preferably, the water content of the mineralized solid waste obtained from the solid-liquid phase separation in step S2 is 65%-70%.

[0016] Preferably, the liquid obtained from the solid-liquid phase separation in step S2 is returned to step S1 as an ammonium acetate leaching agent.

[0017] Compared with the prior art, the present invention has the following technical effects: 1. The entire mineralization process of this invention is a mild reaction process at room temperature and pressure. The ammonium acetate leaching and mineralization process helps to improve the efficiency and capacity of mineralization of low-risk solid waste and contributes to carbon emission reduction. 2. Using ammonium acetate for extraction can enhance the inorganic C and N nutrient content of low-risk solid waste, improve its physicochemical properties such as pH, nutrient composition, and granular structure, and enhance its water retention and moisture retention performance by blending it with waste diapers, which is conducive to rapid plant establishment and sustainable growth. 3. The method for accelerating the mineralization of low-risk solid waste and preparing soil-like matrix with ammonium acetate provided by the present invention is simple to operate, safe and reliable, can reduce the stockpiling of solid waste and improve the utilization rate of bulk solid waste resources, and has significant environmental and social benefits. Attached Figure Description

[0018] Figure 1 The present invention relates to the cyclic leaching of ammonium acetate and glycine from low-risk solid waste supernatant Ca. 2+ Concentration (0.5g steel slag leached at a liquid-to-solid ratio of 10:1); Figure 2 This is a comparison chart of the mineralized solid waste capacity of each system in this invention. Detailed Implementation

[0019] The present invention will be further described below with reference to the embodiments and accompanying drawings, but this does not limit the present invention in any way. Any changes or substitutions made based on the teachings of the present invention shall fall within the protection scope of the present invention.

[0020] Example 1 This embodiment of the method for accelerating the mineralization of low-risk solid waste and preparing soil-like matrix using ammonium acetate includes the following steps: S1. Leaching of active calcium components: 10g of steel slag (chemical composition shown in Table 1) was mixed with ammonium acetate leaching agent at a liquid-to-solid ratio of 10:1. The mixture was stirred at 50℃ for 40 minutes at a stirring speed of 900 rpm until the supernatant of the solution contained Ca. 2+ With a constant concentration, the supernatant Ca 2+ The concentration change within 10 minutes is less than 50 mg / L; the ammonium acetate leaching agent is a 0.5 mol / L ammonium acetate solution; Table 1: Main Chemical Components of Steel Slag ; S2, CO2 carbon mineralization reaction: Flue gas with a CO2 content of 50% (volume fraction) is introduced into the slurry of step S1 at a flow rate of 200 ml / min, and the mixture is continuously stirred until the pH of the slurry drops to 6.7. When the pH of the slurry no longer changes, the mineralization reaction is considered to be over. The CO2 gas supply is stopped, and solid-liquid phase separation is performed to obtain mineralized solid waste and liquid. The water content of the mineralized solid waste is 65%, and the liquid is returned to step S1 as ammonium acetate leaching agent. S3. Preparation of soil-like matrix: Add 5cm waste diaper fragments to the mineralized solid waste and mix well. The amount of waste diaper fragments added is 2% of the mass of the mineralized solid waste. Spray water into the mixture and adjust the moisture content to 80% to obtain the soil-like matrix.

[0021] Example 2 This embodiment utilizes ammonium acetate to accelerate the mineralization of low-risk solid waste and prepare a soil-like matrix. The difference from Example 1 is that in step S1, the reaction is carried out at 20°C for 40 minutes at a stirring speed of 800 rpm, and the ammonium acetate leaching agent is a 0.5 mol / L ammonium acetate solution; in step S2, the gas flow rate is 500 ml / min, and the reaction is continued until the slurry pH drops to 7.0, the water content of the mineralized solid waste is 68%, the size of the waste diaper fragments is 3 cm, the amount of waste diaper fragments added is 1.5%, and the water content of the mixture is 80%.

[0022] Example 3 This embodiment utilizes ammonium acetate to accelerate the mineralization of low-risk solid waste and prepare a soil-like matrix. The method differs from Example 1 in that: in step S1, the reaction is carried out at 80°C for 60 minutes with a stirring speed of 1000 rpm, and the ammonium acetate leaching agent is a 0.5 mol / L ammonium acetate solution; in step S2, the gas flow rate is 500 ml / min, and the reaction is continued until the slurry pH drops to 7.0, the water content of the mineralized solid waste is 68%, the size of the waste diaper fragments is 5 cm, the amount of waste diaper fragments added is 3%, and the water content of the mixture is 82%.

[0023] Example 4 This embodiment utilizes ammonium acetate to accelerate the mineralization of low-risk solid waste and prepare a soil-like matrix. The method differs from Example 1 in that electric furnace slag is used. In step S1, the low-risk solid waste and ammonium acetate leaching agent are mixed at a liquid-to-solid ratio of 5:1 and stirred at 20°C for 30 minutes at a stirring speed of 800 rpm. The ammonium acetate leaching agent is a 0.3 mol / L ammonium acetate solution. In step S2, the slurry pH drops to 6.0, the water content of the mineralized solid waste is 65%, the size of the waste diaper fragments is 3 cm, the amount of waste diaper fragments added is 1.5%, and the water content of the mixture is 80%.

[0024] Example 5 This embodiment utilizes ammonium acetate to accelerate the mineralization of low-risk solid waste and prepare a soil-like matrix. The method differs from Example 1 in that it uses construction solid waste. In step S1, the low-risk solid waste and ammonium acetate leaching agent are mixed at a liquid-to-solid ratio of 20:1 and stirred at 80°C for 60 minutes at a stirring speed of 1200 rpm. The ammonium acetate leaching agent is a 1.0 mol / L ammonium acetate solution. In step S2, the slurry pH drops to 7.0, the water content of the mineralized solid waste is 70%, the size of the waste diaper fragments is 5 cm, the amount of waste diaper fragments added is 3%, and the water content of the mixture is 85%.

[0025] Example 6 This embodiment utilizes ammonium acetate to accelerate the mineralization of low-risk solid waste and prepare a soil-like matrix. The method differs from Example 1 in that: in step S1, the low-risk solid waste and ammonium acetate leaching agent are mixed at a liquid-to-solid ratio of 12.5:1 and stirred at 50°C for 45 minutes at a stirring speed of 1000 rpm. The ammonium acetate leaching agent is a 0.65 mol / L ammonium acetate solution. In step S2, the slurry pH drops to 6.5, the water content of the mineralized solid waste is 67.5%, the size of the waste diaper fragments is 4 cm, the amount of waste diaper fragments added is 2.25%, and the water content of the mixture is 82.5%.

[0026] Comparative Experiment 1 Comparative Example 1 followed the method of Example 1, except that the stirring speed was 200 rpm. Comparative Example 2 followed the method of Example 1, except that a 5 mol / L ammonium acetate solution was used, the liquid-to-solid ratio was 30:1, and no diaper flakes were added. The physicochemical property test data of the mineralization process of Examples 1-3 and Comparative Examples 1-2 are shown in Table 2. Table 2: Detection data of various physicochemical properties during the mineralization process This invention first performs calcium ion leaching, CO2 mineralization, and solid waste separation in the accelerated leaching process of ammonium acetate. Throughout the process, the mineralization steps and parameters are limited, while also considering issues such as mineralization effect and cost. A comparison of Example 1 and Comparative Example 1 shows that a too-low stirring rate during the ammonium acetate leaching process is detrimental to calcium ion leaching. 2+ Leaching reduces its mineralization capacity. Comparing Examples 2 and 3 with Comparative Example 2, it can be seen that the water retention capacity of the mineralized solid waste in Comparative Example 2 is insufficient, which is not conducive to plant establishment in the plant growth and germination experiment. At the same time, high concentration of ammonium acetate does not significantly promote mineralization capacity. Considering the cost of the extractant, setting the ammonium acetate concentration to 0.3 mol / L-1.0 mol / L is scientifically reasonable.

[0027] Comparative Experiment 2 This comparative experiment follows Example 1, except that the ammonium acetate leaching agent is a 0.3 mol / L ammonium acetate solution; Comparative Example 3 follows the method of Example 1, but the leaching agent is a 0.5 mol / L glycine solution; Comparative Example 4 follows the method of Example 1, but water is used instead of the leaching agent (no leaching agent is added). The experimental results are shown in the appendix. Figure 1 Appendix Figure 2 As shown; from the appendix Figure 1 It can be seen that the 0.3 mol / L ammonium acetate solution is more effective at leaching calcium ions than the 0.5 mol / L glycine solution and pure aqueous solution. Figure 2 It can be seen that the carbon fixation capacity of each leaching agent decreases with increasing cycle number, but the carbon fixation capacity of 0.3 mol / L ammonium acetate solution remains higher than that of 0.5 mol / L glycine solution and pure aqueous solution after multiple cycles (see attached). Figure 2 The terms 1st, 2nd, and 3rd refer to the number of extraction cycles.

Claims

1. A method for accelerating the mineralization of low-risk solid waste and preparing a soil-like matrix using ammonium acetate, characterized in that, Includes the following steps: S1. Leaching of active calcium components: Low-risk solid waste is mixed with ammonium acetate leaching agent, and the mixture is stirred until the supernatant of the solution contains Ca. 2+ The concentration is constant; the ammonium acetate leaching agent is an ammonium acetate solution of 0.3 mol / L to 1.0 mol / L; the solid waste and the ammonium acetate leaching agent are mixed at a liquid-solid ratio of 5-20:1 and stirred at 20℃-80℃ for 30-60 minutes; the stirring speed is 800 rpm-1200 rpm; the low-risk solid waste is steel slag. S2, CO2 carbon mineralization reaction: CO2 gas is introduced into the slurry of step S1 and stirred continuously until the pH of the slurry no longer changes. Then, the CO2 gas supply is stopped, and solid-liquid phase separation is carried out to obtain mineralized solid waste and liquid respectively. When the pH of the slurry drops to 6.0-7.0, the mineralization reaction is considered to be over. S3. Preparation of soil-like matrix: Add waste diaper fragments with a size of 3cm-5cm to the mineralized solid waste obtained in step S2 and mix well. The amount of waste diaper fragments added is 1.5%-3% of the mass of the mineralized solid waste. Spray water into the mixture and adjust the moisture content to 80%-85% to obtain the soil-like matrix.

2. The method for accelerating the mineralization of low-risk solid waste and preparing a soil-like matrix using ammonium acetate according to claim 1, characterized in that, S1 step supernatant Ca 2+ The concentration change within 10 minutes was less than 50 mg / L.

3. The method for accelerating the mineralization of low-risk solid waste and preparing a soil-like matrix using ammonium acetate according to claim 1, characterized in that, The CO2-containing gas in step S2 is high-temperature flue gas from a smelter that has undergone desulfurization, denitrification, and dust removal.

4. The method for accelerating the mineralization of low-risk solid waste and preparing a soil-like matrix using ammonium acetate according to claim 1, characterized in that, The water content of the mineralized solid waste obtained from the solid-liquid phase separation in step S2 is 65%-70%.

5. The method for accelerating the mineralization of low-risk solid waste and preparing a soil-like matrix using ammonium acetate according to claim 1, characterized in that, The liquid obtained from the solid-liquid phase separation in step S2 is returned to step S1 as an ammonium acetate leaching agent.

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