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

Abstract

The invention discloses a method for accelerating mineralization of low-risk solid wastes and preparing a soil-like matrix by using ammonium acetate. The method comprises the following steps: leaching of an active calcium component, CO2 carbon mineralization reaction and preparation of the soil-like matrix. The whole mineralization process is a normal-temperature and normal-pressure mild reaction process, the low-risk solid waste mineralization efficiency and capacity can be improved through the ammonium acetate extraction and mineralization process, and carbon emission reduction is promoted; ammonium acetate is used for extraction, the content of inorganic C and N nutrients of low-risk solid waste can be increased, the pH, nutritional ingredients, granular structures and other physicochemical properties of the low-risk solid waste can be improved, the water retention and soil moisture conservation performance of the low-risk solid waste can be improved by blending waste diapers, and rapid field planting and sustainable growth of plants are facilitated; the method is easy to operate, safe and reliable, solid waste stockpiling can be reduced, the utilization rate of bulk solid waste resources is increased, and remarkable environmental benefits and social benefits are achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of mineralizer preparation, and particularly relates to a method for accelerating the mineralization of low-risk solid waste and preparing a soil-like matrix by utilizing ammonium acetate. Background Art

[0002] Low-risk solid wastes such as steel slag, copper slag, and construction solid waste are piled up in large quantities and are difficult to be utilized on a large scale. Low-risk solid wastes contain a large amount of calcium oxide, which is an important way to help reduce carbon emissions under the current background of carbon peak and carbon neutrality. However, conventional leaching agents have problems such as harsh solid waste mineralization conditions, high costs, difficulty in regeneration, and poor economic benefits. Therefore, finding low-cost, green leaching agents is a key link in significantly improving the mineralization efficiency and capacity of smelting slag.

[0003] For the comprehensive utilization of low-risk solid waste, although roadbed materials, building materials, ceramics, glass-ceramics, etc. can absorb some solid waste, the market recognition is low, and the ultimate goal of large-scale solid waste absorption and disposal has not been achieved. Ecological disposal improves the physical and chemical properties of solid waste in order to support the sustainable growth of vegetation. However, low-risk solid waste lacks nutrients and has poor water retention performance, making it unsuitable for direct use in ecological disposal.

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

[0005] In the prior art, the patent with publication number CN117716968A discloses an artificial technical soil and its preparation method, which prepares hydrothermal carbon by hydrothermal treatment of organic solid waste, and extracts soil biological mixed liquid and mixes it with urban solid waste to prepare technical soil, which can also be used for large-scale disposal of urban solid waste. However, the organic solid waste hydrothermal treatment conditions in this patent are harsh, energy consumption is high, and the cycle is long, which cannot achieve green and efficient large-scale disposal of urban solid waste.

[0006] Therefore, it is very necessary to develop a method for accelerating the mineralization of low-risk solid waste and preparing a soil-like matrix using ammonium acetate to overcome the defects of existing accelerated calcium-containing solid waste mineralization leaching agents, such as high cost, long cycle, and poor mineralization effect, and to further improve the nutrient content of solid waste. Summary of the invention

[0007] In order to solve the above technical problems, the object of the present invention is to provide a method for accelerating the mineralization of low-risk solid waste and preparing a soil-like matrix using ammonium acetate.

[0008] The object of the present invention is achieved by comprising the following steps: S1. Extraction of active calcium components: Mix low-risk solid waste with ammonium acetate leaching agent and stir until the supernatant Ca in the solution is 2+ Constant concentration; S2, CO2 carbon mineralization reaction: introducing CO2 gas into the slurry of step S1 and continuously stirring until the pH of the slurry no longer changes, stopping the CO2 gas supply, and performing solid-liquid phase separation to obtain mineralized solid waste and liquid respectively; S3. Preparation of soil-like matrix: Add used diaper fragments with a size of 3cm-5cm to the mineralized solid waste obtained in step S2 and mix well. The amount of used diaper fragments added is 1.5%-3% of the mass of the mineralized solid waste. Spray water on the mixture and adjust the moisture content to 80%-85% to obtain a soil-like matrix. The water retention capacity of the mineralized solid waste is improved by adding used diapers, in order to provide a new way to accelerate the mineralization of low-risk solid waste and ultimately green large-scale ecological utilization.

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

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

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

[0012] Preferably, the supernatant Ca in step S1 2+ The concentration changes within 10 minutes and is 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, in step S2, when the pH of the slurry drops to 6.0-7.0, the mineralization reaction is considered to be completed.

[0015] Preferably, the water content of the mineralized solid waste obtained by 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 sent back 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 the present invention is a mild reaction process at normal temperature and pressure. The ammonium acetate leaching and mineralization process is beneficial to improving the mineralization efficiency and capacity of low-risk solid waste and promoting 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 physical and chemical properties such as pH, nutrient composition, and aggregate structure, and improve its water and moisture retention performance by adding used diapers, which is conducive to the rapid colonization and sustainable growth of plants; 3. The method provided by the present invention for accelerating the mineralization of low-risk solid waste and preparing a soil-like matrix with ammonium acetate is simple to operate, safe and reliable, can reduce the stockpiling of solid waste, improve the utilization rate of bulk solid waste resources, and has significant environmental and social benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 The present invention is a method for cyclically leaching low-risk solid waste supernatant Ca with ammonium acetate and glycine. 2+ Concentration (0.5g slag is leached at a liquid-to-solid ratio of 10:1); Figure 2 It is a comparison chart of the mineralized solid waste capacity of each system of the present invention. DETAILED DESCRIPTION

[0019] The present invention is further described below in conjunction with the embodiments and drawings, but the present invention is not limited in any way. Any changes or substitutions made based on the teachings of the present invention belong to the protection scope of the present invention.

[0020] Example 1 The method of accelerating the mineralization of low-risk solid waste and preparing a soil-like matrix using ammonium acetate in this embodiment includes the following steps: S1. Extraction of active calcium components: 10 g of steel slag (chemical composition see Table 1) was mixed with ammonium acetate leaching agent at a liquid-solid ratio of 10:1, and stirred at 50 °C for 40 min at a stirring speed of 900 rpm until the supernatant Ca in the solution 2+ The concentration is constant, and the supernatant Ca 2+ The concentration changes within 10 minutes and is less than 50 mg / L; the ammonium acetate leaching agent is 0.5 mol / L ammonium acetate solution; Table 1: Main chemical composition of steel slag ; S2, CO2 carbon mineralization reaction: introduce flue gas with a CO2 content of 50% (volume fraction) into the slurry in step S1 at a gas flow rate of 200 ml / min, and continue stirring until the pH of the slurry drops to 6.7 and the pH of the slurry no longer changes, which is considered to be the end of the mineralization reaction. Stop the CO2 gas supply, perform solid-liquid phase separation, and obtain mineralized solid waste and liquid respectively. The water content of the mineralized solid waste is 65%, and the liquid is returned to step S1 as an ammonium acetate leaching agent; S3. Preparation of soil-like matrix: Add used diaper fragments with a size of 5 cm to the mineralized solid waste and mix well. The amount of used diaper fragments added is 2% of the mass of the mineralized solid waste. Spray water on the mixture and adjust the moisture content to 80% to obtain a soil-like matrix.

[0021] Example 2 The method of using ammonium acetate to accelerate the mineralization of low-risk solid waste and prepare a soil-like matrix in this embodiment is based on Example 1, and the difference from Example 1 is that: in step S1, the reaction is stirred at 20°C for 40 minutes, the stirring speed is 800rpm, and the ammonium acid leaching agent is 0.5 moL / L ammonium acetate solution; in step S2, the gas flow rate is 500 ml / min, and when the pH of the slurry drops to 7.0, the moisture 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 moisture content of the mixture is 80%.

[0022] Example 3 The method of using ammonium acetate to accelerate the mineralization of low-risk solid waste and prepare a soil-like matrix in this embodiment is based on Example 1, and the difference from Example 1 is that: in step S1, the reaction is stirred at 80°C for 60 minutes, the stirring speed is 1000rpm, and the ammonium acid leaching agent is 0.5 moL / L ammonium acetate solution; in step S2, the gas flow rate is 500 ml / min, and when the pH of the slurry drops to 7.0, the moisture 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 moisture content of the mixture is 82%.

[0023] Example 4 The method of using ammonium acetate to accelerate the mineralization of low-risk solid waste and prepare a soil-like matrix in this embodiment is based on Example 1, and the difference from Example 1 is that electric furnace slag is used; in step S1, the low-risk solid waste is mixed with an ammonium acetate leaching agent at a liquid-solid ratio of 5:1, and the reaction is stirred for 30 minutes at 20°C, the stirring speed is 800rpm, and the ammonium acetate leaching agent is 0.3 mol / L ammonium acetate solution; in step S2, when the pH of the slurry drops to 6.0, the moisture 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 moisture content of the mixture is 80%.

[0024] Example 5 The method of using ammonium acetate to accelerate the mineralization of low-risk solid waste and prepare a soil-like matrix in this embodiment is based on Example 1, and the difference from Example 1 is that: construction solid waste is used; in step S1, the low-risk solid waste is mixed with an ammonium acetate leaching agent at a liquid-solid ratio of 20:1, and the reaction is stirred at 80°C for 60 minutes, the stirring speed is 1200rpm, and the ammonium acetate leaching agent is 1.0 moL / L ammonium acetate solution; in step S2, when the pH of the slurry drops to 7.0, the moisture 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 moisture content of the mixture is 85%.

[0025] Example 6 The method of accelerating the mineralization of low-risk solid waste and preparing a soil-like matrix using ammonium acetate in this embodiment is based on Example 1, and the difference from Example 1 is: in step S1, the low-risk solid waste is mixed with an ammonium acetate leaching agent at a liquid-solid ratio of 12.5:1, and the reaction is stirred at 50°C for 45 minutes, the stirring speed is 1000rpm, and the ammonium acetate leaching agent is 0.65 moL / L ammonium acetate solution; in step S2, when the pH of the slurry drops to 6.5, the moisture 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 moisture content of the mixture is 82.5%.

[0026] Comparative experiment 1 Comparative Example 1 was carried out according to the method of Example 1, except that the stirring speed was 200 rpm. Comparative Example 2 was carried out according to 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 fragments were added; the physical and chemical property test data of the mineralization process of Examples 1-Example 3 and Comparative Examples 1-Comparative Examples 2 are shown in Table 2; Table 2: Physical and chemical properties test data of mineralization process In the process of ammonium acetate accelerated leaching, the present invention first performs calcium ion leaching, CO2 mineralization and solid waste separation, and limits the mineralization steps and parameters in the whole process, while taking into account the problems of mineralization effect and cost; By comparing Example 1 with Comparative Example 1, it can be seen that too low stirring rate in the ammonium acetate leaching process is not conducive to Ca 2+ Leaching will reduce its mineralization capacity; comparing Example 2, Example 3 and Comparative Example 2, it can be seen that the mineralized solid waste in Comparative Example 2 has insufficient water retention capacity, which is not conducive to plant colonization in plant growth and germination experiments. At the same time, high concentration of ammonium acetate has no significant promotion on mineralization capacity. Considering the cost of the leaching agent, it is scientific and reasonable to set the ammonium acetate concentration to 0.3moL / L-1.0moL / L.

[0027] Comparative experiment 2 This comparative experiment example is based on Example 1, except that the ammonium acetate leaching agent is 0.3 mol / L ammonium acetate solution; Comparative Example 3 is based on the method of Example 1, but the leaching agent is 0.5 mol / L glycine solution; Comparative Example 4 is based on the method of Example 1, but the leaching agent is replaced by water (no leaching agent is added); the experimental results are shown in the attached Figure 1 , Attachment Figure 2 As shown; from the attached Figure 1 It can be seen that the leaching effect of 0.3 mol / L ammonium acetate solution on calcium ions is better than that of 0.5 mol / L glycine solution and pure water solution. Figure 2 It can be seen that the carbon fixation capacity of each leaching agent decreases with the increase of the number of cycles, but the carbon fixation capacity of 0.3 mol / L ammonium acetate solution after multiple cycles is still higher than that of 0.5 mol / L glycine solution and pure water solution (see Appendix Figure 2 1st, 2st, 3st refer to the number of extraction agent cycles).

Claims

1. A method for accelerating the mineralization of low-risk solid waste and preparing a soil-like matrix using ammonium acetate, comprising the following steps: S1. Extraction of active calcium components: Mix low-risk solid waste with ammonium acetate leaching agent and stir until the supernatant Ca in the solution is 2+ Constant concentration; S2, CO2 carbon mineralization reaction: introducing CO2 gas into the slurry of step S1 and continuously stirring until the pH of the slurry no longer changes, stopping the CO2 gas supply, and performing solid-liquid phase separation to obtain mineralized solid waste and liquid respectively; S3. Preparation of soil-like matrix: Add used diaper fragments with a size of 3cm-5cm to the mineralized solid waste obtained in step S2 and mix well. The amount of used diaper fragments added is 1.5%-3% of the mass of the mineralized solid waste. Spray water on the mixture and adjust the moisture content to 80%-85% to obtain a 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 The ammonium acetate leaching agent in step S1 is 0.3 mol / L-1.0 mol / L ammonium acetate solution.

3. The method of accelerating the mineralization of low-risk solid waste and preparing a soil-like matrix using ammonium acetate according to claim 1, characterized in that In step S1, the solid waste is mixed with the ammonium acetate leaching agent in a liquid-to-solid ratio of 5 to 20:1, and stirred for reaction at 20°C to 80°C for 30min to 60min.

4. The method of 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 stirring speed in step S1 is 800 rpm-1200 rpm.

5. The method of 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 changes within 10 minutes and is less than 50 mg / L.

6. The method of 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 the high-temperature flue gas from the smelter that has undergone desulfurization, denitrification and dust removal.

7. The method of accelerating the mineralization of low-risk solid waste and preparing a soil-like matrix using ammonium acetate according to claim 1, characterized in that In step S2, when the pH of the slurry drops to 6.0-7.0, the mineralization reaction is considered to be completed.

8. The method of 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 by solid-liquid phase separation in step S2 is 65%-70%.

9. The method of 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 by solid-liquid phase separation in step S2 is sent back to step S1 as ammonium acetate leaching agent.

Images