Magnesium-based carbon dioxide absorbent prepared from ferromagnesian tailings and its preparation method

Abstract

This invention belongs to the field of air pollution control and tailings recycling technology, specifically relating to a method for preparing a magnesium-based carbon dioxide absorbent from ferromagnesian tailings, comprising the following steps: (1) crushing the ferromagnesian tailings and sieving them to obtain powder with uniform particle size; (2) mixing the powder obtained in step (1) with ammonium acetate solution, drying it thoroughly, and then calcining it in a muffle furnace; (3) adding the powder obtained in step (2) into an aqueous acetic acid solution, reacting it in an ultrasonic-microwave reactor, separating the solid and liquid, adjusting the pH to 7 by adding ammonia to the leachate, filtering to remove impurities, and continuing to add ammonia to the leachate to adjust the pH to 12 to obtain a magnesium hydroxide slurry; (4) filtering the magnesium hydroxide slurry obtained in step (3), and drying and washing the obtained solid at least twice to obtain the magnesium-based carbon dioxide absorbent. The magnesium-based carbon dioxide absorbent prepared by this invention has good absorption performance for CO2 gas.

Description

Technical Field

[0001] This invention relates to the field of carbon dioxide absorbent preparation, and in particular to a method for preparing magnesium-based carbon dioxide absorbent from ferromagnesian tailings under field-enhanced conditions. Background Technology

[0002] Following the Industrial Revolution, rapid industrial development and the expansion of human activity led to massive energy consumption in pursuit of economic growth. This resulted in the emission of large amounts of greenhouse gases, such as carbon dioxide, into the atmosphere. The sharp increase in their concentration caused an excessive warming effect on the Earth's surface, leading to ground temperatures exceeding normal levels and creating the greenhouse effect. On May 18, 2022, the World Meteorological Organization (WMO) released its "State of the Global Climate 2021" report in Geneva. The report showed that global atmospheric greenhouse gas concentrations reached a record high in 2020, with global carbon dioxide concentration reaching 413.2 ppm (parts per million), 149% of pre-industrial levels.

[0003] Utilizing the reaction of metal ions in minerals (mainly Mg) 2+ Ca 2+ Compared with other methods, CO2 sequestration by reacting with CO2 to convert it into carbonates or bicarbonates has many advantages: first, the reaction is relatively easy to occur; second, the products have no impact on the environment, making it a safe sequestration method; and third, the raw materials used for CO2 sequestration are abundant, have huge reserves, and are inexpensive, thus possessing the potential for large-scale sequestration and economic benefits.

[0004] Ferromagnetic tailings are waste materials left over after mineral mining, with the chemical formula —Mg3Si2O5(OH)4 (Mg can be replaced by Fe). my country has abundant ferromagnesian tailings resources, and using them as raw materials to produce magnesium-based carbon dioxide absorbents has broad prospects.

[0005] Existing methods for preparing magnesium-based absorbents have certain drawbacks.

[0006] First, many methods employ impregnation-calcination pretreatment, which generates harmful substances that pollute the environment.

[0007] Secondly, the low efficiency of directly leaching magnesium ions from minerals results in low yields of magnesium-based absorbents. This is because byproducts generated during the leaching reaction adhere to the surface of solid particles, reducing the solid-liquid contact area and hindering the continued leaching reaction. Consequently, a large number of magnesium ions inside the mineral particles cannot participate in the reaction and precipitate, significantly reducing the leaching rate. This leads to most of the magnesium remaining in the mineral without precipitating, resulting in the mineral not being utilized to its fullest potential.

[0008] In addition, some acid leaching methods use strong acids that have a strong corrosive effect on equipment, are very harmful to the environment, and are expensive.

[0009] Therefore, inventing a method for preparing magnesium-based absorbents that yields high output, produces no secondary pollution during the reaction process, and has low raw material and energy consumption and low cost is of great significance for the large-scale production of magnesium-based absorbents for CO2 absorption. The large-scale production of high-performance, low-cost absorbents remains a pressing problem in the field of carbon capture. Summary of the Invention

[0010] The technical problem to be solved by the present invention is to provide a method for preparing magnesium-based carbon dioxide absorbent from field-enhanced ferromagnesian tailings that can solve the above-mentioned problems, improve the leaching rate of magnesium ions in the leaching reaction and avoid secondary pollution.

[0011] To address the aforementioned technical problems, this invention discloses a method for preparing a magnesium-based carbon dioxide absorbent from ferromagnesian tailings, the method comprising the following steps:

[0012] S1. The ferromagnesian tailings are crushed and sieved to obtain ferromagnesian tailings powder;

[0013] S2. After thoroughly mixing and drying the iron-magnesium tailings powder with ammonium acetate solution, place it in a muffle furnace for calcination;

[0014] S3. The calcined powder obtained in step S2 is added to an acetic acid aqueous solution and subjected to microwave heating and ultrasonic cavitation bubble vibration reaction. After solid-liquid separation, the pH is adjusted to 7 by adding ammonia to the leachate, and impurities are removed by filtration. Ammonia is then added to the leachate to adjust the pH to 12, resulting in magnesium hydroxide slurry.

[0015] S4. The magnesium hydroxide slurry is filtered, and the resulting solid is dried and washed to obtain a magnesium-based carbon dioxide absorbent.

[0016] Furthermore, in step S3, the microwave power of the microwave heating is 500-1000W; the ultrasonic power of the ultrasonic cavitation bubble vibration reaction is 200-500W; and the reaction time of the microwave heating and ultrasonic cavitation bubble vibration reaction is 1-2 hours.

[0017] Furthermore, in step S3, the reaction temperature of the microwave heating and ultrasonic cavitation bubble vibration reaction is 25-80℃. Furthermore, in step S3, the volume ratio of the acetic acid aqueous solution to the mass of the ferromagnesian tailings is 5-20; the concentration of the acetic acid aqueous solution is 0.1-4 mol / L.

[0018] Furthermore, the iron-magnesium tailings are natural minerals containing Fe2O3, SiO2 and MgO, and the powder particle size of the iron-magnesium tailings powder is <850μm.

[0019] Furthermore, in step S2, the ammonium acetate solution is a mixture of ammonium acetate particles and deionized water.

[0020] Furthermore, in step S2, the calcination temperature is 600–700°C, and the calcination time is 1–2 hours.

[0021] Furthermore, in step S4, the magnesium hydroxide slurry is dried at a temperature below 50°C for 2 to 4 hours.

[0022] Furthermore, in step S2, during the calcination in the muffle furnace, the generated ammonia gas is collected to prepare ammonia water, which is used in step S3.

[0023] The present invention also discloses a magnesium-based carbon dioxide absorbent prepared from ferromagnesian tailings, which is prepared by any of the above-described methods for preparing magnesium-based carbon dioxide absorbents from ferromagnesian tailings.

[0024] Compared with the prior art, the technical solution of the present invention has the following beneficial effects:

[0025] 1. Compared with the prior art, the present invention uses microwave heating technology, which has the characteristics of rapid and selective heating of materials, clean and easy control, and catalytic effect on chemical reaction. In addition, it can also promote the formation of cracks and pores inside mineral particles, accelerate the renewal of reaction interface, and since polar molecules (such as acetic acid) can generate high-frequency vibration under an external electric field, molecular stirring can be achieved without additional stirring measures, thus effectively improving the leaching effect.

[0026] The strong jets and local micro-impacts generated by ultrasonic cavitation bubble vibrations on the solid surface can significantly reduce the surface tension and friction of the liquid, and destroy the boundary layer at the solid-liquid interface, thereby enhancing the mixing between the liquid and solid phases. Furthermore, cavitation can cause microscopic vibrations within the solution, accelerating molecular diffusion and making the reaction more complete earlier.

[0027] 2. In the preparation method of the present invention, ammonia gas generated in the calcination process can be collected, and a pH adjustment process can be carried out after the ammonia water leaching reaction. The main component of the waste liquid remaining after the precipitate slurry is ammonium acetate, which can be used in the calcination process. The leaching agent is acetic acid, which can be recycled and reused due to its volatility. It has little environmental pollution and little corrosion to equipment.

[0028] 3. In the preparation method of the present invention, the iron-magnesium tailings powder contains a large amount of magnesium silicate. After chemical impregnation and calcination, the effective components are activated, which has a certain promoting effect on the leaching effect. Secondly, the iron-magnesium tailings selected in the present invention are mainly composed of Mg3Si2O5(OH)4, which is abundant in nature and inexpensive. Attached Figure Description

[0029] Figure 1 This is a process flow diagram of the preparation method of magnesium-based carbon dioxide absorbent prepared from ferromagnesian tailings in this invention. Detailed Implementation

[0030] The technical solution of the present invention will now be described in detail with reference to the accompanying drawings.

[0031] Example 1

[0032] (1) First, crush and sieve the ferromagnesian tailings (the main component is Mg3Si2O5(OH)4) to obtain powder with a particle size of <125μm;

[0033] (2) Weigh 5g of the powder obtained in step (1) and put it into 100ml of 4mol / L acetic acid aqueous solution. React in an ultrasonic-microwave reactor for 1h. The ultrasonic-microwave reactor parameters are: ultrasonic power 200W, microwave power 1000W, and reaction temperature 80℃.

[0034] (3) Measure the Mg content in the leachate obtained in step (2) using a chromatograph. 2+ concentration.

[0035] Example 2

[0036] (1) First, crush and sieve the ferromagnesian tailings (the main component is Mg3Si2O5(OH)4) to obtain powder with a particle size of <125μm;

[0037] (2) Weigh 5g of the powder obtained in step (1) and put it into 100ml of 4mol / L acetic acid aqueous solution. React in an ultrasonic-microwave reactor for 1h. The ultrasonic-microwave reactor parameters are: ultrasonic power 200W, microwave power 1000W, and reaction temperature 50℃.

[0038] (3) Measure the Mg content in the leachate obtained in step (2) using a chromatograph. 2+ concentration.

[0039] Example 3

[0040] (1) First, crush and sieve the ferromagnesian tailings (the main component is Mg3Si2O5(OH)4) to obtain powder with a particle size of <125μm;

[0041] (2) Weigh 5g of the powder obtained in step (1) and put it into 100ml of 4mol / L acetic acid aqueous solution. React in an ultrasonic-microwave reactor for 1h. The ultrasonic-microwave reactor parameters are: ultrasonic power 200W, microwave power 1000W, and reaction temperature 25℃.

[0042] (3) Measure the Mg content in the leachate obtained in step (2) using a chromatograph. 2+ concentration.

[0043] Example 4

[0044] (1) First, crush and sieve the iron-magnesium tailings (the main component is Mg3Si2O5(OH)4) to obtain powder with a particle size of 125-300μm;

[0045] (2) Weigh 5g of the powder obtained in step (1) and put it into 100ml of 4mol / L acetic acid aqueous solution. React in an ultrasonic-microwave reactor for 1h. The ultrasonic-microwave reactor parameters are: ultrasonic power 200W, microwave power 1000W, and reaction temperature 25℃.

[0046] (3) Measure the Mg content in the leachate obtained in step (2) using a chromatograph. 2+ concentration.

[0047] Example 5

[0048] (1) First, crush and sieve the iron-magnesium tailings (the main component is Mg3Si2O5(OH)4) to obtain powder with a particle size of 300-850μm;

[0049] (2) Weigh 5g of the powder obtained in step (1) and put it into 100ml of 4mol / L acetic acid aqueous solution. React in an ultrasonic-microwave reactor for 1h. The ultrasonic-microwave reactor parameters are: ultrasonic power 200W, microwave power 1000W, and reaction temperature 25℃.

[0050] (3) Measure the Mg content in the leachate obtained in step (2) using a chromatograph. 2+ concentration.

[0051] Example 6

[0052] (1) First, crush and sieve the ferromagnesian tailings (the main component is Mg3Si2O5(OH)4) to obtain powder with a particle size of <125μm;

[0053] (2) Weigh 20g of the powder obtained in step (1) and put it into 100ml of 4mol / L acetic acid aqueous solution. React in an ultrasonic-microwave reactor for 1h. The ultrasonic-microwave reactor parameters are: ultrasonic power 200W, microwave power 1000W, and reaction temperature 25℃.

[0054] (3) Measure the Mg content in the leachate obtained in step (2) using a chromatograph. 2+ concentration.

[0055] Example 7

[0056] (1) First, crush and sieve the ferromagnesian tailings (the main component is Mg3Si2O5(OH)4) to obtain powder with a particle size of <125μm;

[0057] (2) Weigh 10g of the powder obtained in step (1) and put it into 100ml of 4mol / L acetic acid aqueous solution. React in an ultrasonic-microwave reactor for 1h. The ultrasonic-microwave reactor parameters are: ultrasonic power 200W, microwave power 1000W, and reaction temperature 25℃.

[0058] (3) Measure the Mg content in the leachate obtained in step (2) using a chromatograph. 2+ concentration.

[0059] Examples 8-10

[0060] Except for the following differences, Examples 8-10 are the same as Example 1, and the relevant results are shown in the table below.

[0061] (1) First, crush and sieve the ferromagnesian tailings (the main component is Mg3Si2O5(OH)4) to obtain powder with a particle size of <125μm;

[0062] (2) Weigh 5g of the powder obtained in step (1) and put it into 100ml of 4mol / L acetic acid aqueous solution. React in an ultrasonic-microwave reactor for 1h. The ultrasonic-microwave reactor parameters are: ultrasonic power 200W, microwave power 1000W, and reaction temperature 25℃.

[0063] (3) Measure the Mg content in the leachate obtained in step (2) using a chromatograph. 2+ Concentration. The results are shown in Table 1 below:

[0064] Table 1

[0065]

[0066] Examples 11-16

[0067] Except for the following differences, Examples 11-16 are the same as Example 1, and the relevant results are shown in the table below.

[0068] (1) First, crush and sieve the ferromagnesian tailings (the main component is Mg3Si2O5(OH)4) to obtain powder with a particle size of <125μm;

[0069] (2) Weigh 5g of the powder obtained in step (1) and put it into 100ml of 4mol / L acetic acid aqueous solution. React in an ultrasonic-microwave reactor for 1h. The ultrasonic-microwave reactor parameters are: ultrasonic power 200W, microwave power 1000W, and reaction temperature 25℃.

[0070] (3) Measure the Mg content in the leachate obtained in step (2) using a chromatograph. 2+ Concentration. The results are shown in Table 2 below:

[0071] Table 2

[0072]

[0073] Example 17

[0074] (1) First, crush and sieve the ferromagnesian tailings (the main component is Mg3Si2O5(OH)4) to obtain powder with a particle size of <125μm;

[0075] (2) After thoroughly mixing the powder obtained in step (1) with ammonium acetate solution and drying it, place it in a muffle furnace and calcine at 700°C for 2 hours;

[0076] (3) Weigh 5g of the powder obtained in step (2) and put it into 100ml of 1mol / L acetic acid aqueous solution. React in an ultrasonic-microwave reactor for 1h. The ultrasonic-microwave reactor parameters are: ultrasonic power 500W, microwave power 1000W, and reaction temperature 80℃.

[0077] (4) Measure the Mg content in the leachate obtained in step (3) using a chromatograph. 2+ concentration.

[0078] Comparative Example 1

[0079] (1) First, crush and sieve the ferromagnesian tailings (the main component is Mg3Si2O5(OH)4) to obtain powder with a particle size of <125μm;

[0080] (2) Weigh 5g of the powder obtained in step (2) and put it into 100ml of 1mol / L acetic acid aqueous solution. React in an ultrasonic-microwave reactor for 1h. The parameters of the ultrasonic-microwave reactor are: microwave power 1000W, magnetic stirring speed 200r / min, and reaction temperature 80℃.

[0081] (3) Measure the Mg content in the leachate obtained in step (2) using a chromatograph. 2+ concentration.

[0082] Comparative Example 2

[0083] (1) First, crush and sieve the ferromagnesian tailings (the main component is Mg3Si2O5(OH)4) to obtain powder with a particle size of <125μm;

[0084] (2) Weigh 5g of the powder obtained in step (2) and put it into 100ml of 1mol / L acetic acid aqueous solution. React in a water bath for 1h at a reaction temperature of 80℃.

[0085] (3) Measure the Mg content in the leachate obtained in step (2) using a chromatograph. 2+ concentration.

[0086] Comparative Example 3

[0087] (1) First, crush and sieve the ferromagnesian tailings (the main component is Mg3Si2O5(OH)4) to obtain powder with a particle size of <125μm;

[0088] (2) Place the powder obtained in step (1) into a muffle furnace and calcine at 700°C for 2 hours;

[0089] (3) Weigh 5g of the powder obtained in step (2) and put it into 100ml of 1mol / L acetic acid aqueous solution. React in an ultrasonic-microwave reactor for 1h. The ultrasonic-microwave reactor parameters are: ultrasonic power 500W, microwave power 1000W, and reaction temperature 80℃.

[0090] (4) Measure the Mg content in the leachate obtained in step (2) using a chromatograph. 2+ concentration.

[0091] The above examples and comparative examples used chromatographs to measure the Mg2+ leaching concentration data. The results are shown in Table 3:

[0092] Table 3

[0093]

[0094]

[0095] By comparing Examples 1, 2, and 3; Examples 1, 4, and 5; Examples 1, 6, and 7; and Examples 1, 8, 9, and 10, it was found that the higher the reaction temperature, the smaller the particle size of the ferromagnesian tailings, the smaller the liquid-to-solid ratio, and the higher the acetic acid concentration, the better the Mg content. 2+ The higher the leaching concentration.

[0096] Comparing the results of Examples 11-16 with those of Comparative Examples 1-2, after introducing microwave and ultrasonic treatments, Mg 2+ The leaching concentration increased by 26.77% to 84.37%.

[0097] Comparing Examples 16, 17 and Comparative Example 3, calcination resulted in Mg... 2+The leaching concentration increased by 785.89%, and the chemical impregnation followed by calcination resulted in Mg... 2+ The leaching concentration increased by 977.96%, and chemical impregnation followed by calcination resulted in a higher Mg concentration compared to direct calcination. 2+ The leaching concentration increased by 21.68%.

[0098] Preparation of magnesium-based carbon dioxide absorbent

[0099] After solid-liquid separation of the leachate and waste residue, impurities are removed by adding ammonia to the leachate to adjust the pH to 7 and filtering. Ammonia is then added to the leachate to adjust the pH to 12, resulting in magnesium hydroxide slurry. The magnesium hydroxide slurry is then filtered, and the resulting solid is dried and washed at least twice. The drying temperature is below 50°C, and the drying time is 2 hours, to obtain magnesium-based carbon dioxide absorbent.

[0100] CO2 absorption capacity test

[0101] Magnesium-based carbon dioxide absorbents should be ground into small particles before use to increase their absorption surface area and enhance their absorption capacity.

[0102] In this embodiment, in order to verify the carbon dioxide absorption capacity of the magnesium-based carbon dioxide absorbent prepared in Example 17, the magnesium-based carbon dioxide absorbent prepared in Example 17 was mixed with deionized water in different amounts to form Mg(OH)2 slurries with different Mg contents. Under the reaction conditions of 40°C and 850 r / min, CO2 was introduced into the slurry at a flow rate of 400 ml / min and the reaction was carried out for 50 min.

[0103] It should be noted that the formula for calculating absorption efficiency is as follows:

[0104] Magnesium-based absorbent absorption efficiency = (Mg 2+ Final concentration - Mg 2+ (Initial concentration) / (Theoretical Mg concentration in absorbent) * 100%

[0105] The magnesium-based absorbent used in this embodiment is a product formed only after steps (1)-(4).

[0106] The following experimental data were obtained, and the results are shown in Table 4:

[0107] Table 4

[0108]

[0109] The experimental data above show that the absorbent prepared in Example 17, when mixed with deionized water in different amounts to form a slurry, achieved an absorption efficiency of over 70%, demonstrating good results.

[0110] Due to the reaction system Mg2+ A hydrolysis reaction occurs, so the initial solution contains a certain concentration of Mg. 2+ It exists. It can be seen that the Mg(OH)₂ slurry with a theoretical Mg concentration of 1500 ppm contains Mg before reaction. 2+ The concentration was lowest, and after 50 minutes of reaction, Mg... 2+ The concentration has reached the theoretical maximum, and the absorption efficiency is also at its highest.

[0111] When preparing Mg(OH)2 slurry using the magnesium-based absorbent obtained by this method, the above experimental data can be used as a reference to maximize the utilization of Mg's carbon fixation ability and achieve a high absorption efficiency.

[0112] All raw materials used in this invention are inexpensive substances with virtually no environmental harm. The preparation process is simple, and the CO2 absorption effect is excellent. It is suitable for large-scale production and utilization.

[0113] As can be seen from the above, the magnesium-based absorbent prepared by the method provided by the present invention has high yield and good effect. During the preparation process, the reagents can be recycled and reused, the cost is low, the damage to equipment is small, and there is almost no secondary pollution to the environment. It can make up for some of the defects of the existing technology.

[0114] In addition, the magnesium-based carbon dioxide absorbent prepared by the preparation method of the present invention can be used to capture greenhouse gas CO2, as well as acid gases such as SO2, and can efficiently absorb carbon dioxide and sulfur dioxide in flue gas. The magnesium-based carbon dioxide absorbent prepared by the preparation method of the present invention has a large yield and good performance, and can be applied to the capture of carbon dioxide in industry.

[0115] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the specific embodiments described above. The specific embodiments and descriptions in the specification are merely for further illustrating the principles of the invention. Various changes and modifications can be made to the present invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the claims and their equivalents.

Claims

1. A method for preparing a magnesium-based carbon dioxide absorbent from ferromagnesian tailings, characterized in that, The method includes the following steps: S1. The iron-magnesium tailings are crushed and sieved to obtain iron-magnesium tailings powder. The iron-magnesium tailings are natural minerals containing Fe2O3, SiO2 and MgO, and the powder particle size of the iron-magnesium tailings powder is <850μm. S2. After thoroughly drying the iron-magnesium tailings powder mixed with ammonium acetate solution, it is placed in a muffle furnace for calcination; the ammonium acetate solution is a mixture of ammonium acetate particles and deionized water; the calcination temperature is 600~700℃, and the calcination time is 1~2h; during the calcination in the muffle furnace, the generated ammonia gas is collected to prepare ammonia water, which is used in step S3; S3. The calcined powder obtained in step S2 is leached in an acetic acid aqueous solution, wherein the volume ratio of the acetic acid aqueous solution to the mass of the ferromagnesian tailings is 5-20; the concentration of the acetic acid aqueous solution is 0.1-4 mol / L; the leaching process involves microwave heating and ultrasonic cavitation bubble vibration reaction, wherein the microwave power of the microwave heating is 500-1000W; the ultrasonic power of the ultrasonic cavitation bubble vibration reaction is 200-500W; the reaction time of the microwave heating and ultrasonic cavitation bubble vibration reaction is 1-2 hours; and the reaction temperature of the microwave heating and ultrasonic cavitation bubble vibration reaction is 25-80℃; after solid-liquid separation, the pH is adjusted to 7 by adding ammonia to the leachate, impurities are removed by filtration, and ammonia is added to the leachate again to adjust the pH to 12, thereby obtaining a magnesium hydroxide slurry; S4. The magnesium hydroxide slurry is filtered, the resulting solid is washed, and then dried at a temperature below 50°C for 2-4 hours to obtain a magnesium-based carbon dioxide absorbent.

2. A magnesium-based carbon dioxide absorbent prepared from ferromagnesian tailings, characterized in that: It is prepared using the method described in claim 1 for preparing magnesium-based carbon dioxide absorbent from ferromagnesian tailings.

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