Method for directly mineralizing carbon dioxide by using magnesium reducing slag

Abstract

The invention provides a method for directly mineralizing carbon dioxide by using magnesium reducing slag, and belongs to the technical field of comprehensive utilization of steel smelting. The method provided by the invention comprises the following steps: spraying an acid solution to the hot-state magnesium reducing slag, and then mixing with flue gas to react; the concentration of calcium ions in the acidic solution is 650-800 mg / L, the concentration of H2O2 is 20-180 mg / L, and the pH value of the acidic solution is 3.4-4.2. According to the method for fixing the carbon dioxide through direct mineralization of the magnesium reducing slag, high-temperature direct mineralization is conducted through waste heat of the hot magnesium slag, the acid solution is blown to the hot magnesium slag, and the mineralization efficiency is improved. The utilization efficiency of the magnesium reducing slag is improved. The method has the characteristics of simple process, safety in operation and easiness in implementation.

Description

Technical Field

[0001] The present invention relates to the technical field of comprehensive utilization of iron and steel smelting, and particularly relates to a method for directly mineralizing carbon dioxide by using magnesium reduction slag. Background Art

[0002] When magnesium reduction slag is discharged from a metal magnesium smelting plant, it usually has a relatively high temperature. If it is randomly stacked, it will not only cause harm to the surrounding environment, but also result in the loss of the physical sensible heat of the magnesium slag, causing a large amount of heat energy waste. At present, the main utilization method of magnesium reduction slag is to replace part of the raw material to burn cement clinker. Although the utilization value of magnesium reduction slag is improved, secondary calcination will increase the process cost, and the too high content of magnesium oxide in the slag will lead to a decrease in the strength of the cement. Therefore, developing a method for directly mineralizing carbon dioxide by using magnesium reduction slag has important practical significance.

[0003] Patent 202310176603.6 discloses a method for sequestering carbon dioxide by using magnesium reduction slag to produce light magnesium carbonate and co-producing calcium carbonate, which uses an acidic solution to leach magnesium reduction slag to enrich calcium and magnesium ions. This patent adopts a common wet carbon sequestration method, which is prone to problems such as equipment and pipeline corrosion, and has high process energy consumption, generating a large amount of wastewater and causing great environmental protection pressure. Patent 202110062242.3 discloses a recovery process for magnesium oxide reduction slag. This patent adopts a direct mineralization method of external heating and increasing gas partial pressure, without making full use of the physical sensible heat of the magnesium slag, resulting in waste of heat energy, and the external heating increases the process cost. Summary of the Invention

[0004] In order to solve the problems existing in the prior art, the purpose of the present invention is to provide a method for directly mineralizing carbon dioxide by using magnesium reduction slag. The present invention uses hot magnesium reduction slag and adopts a high-temperature direct mineralization method to realize the fixation of carbon dioxide and the utilization of magnesium reduction slag, and has the characteristics of simple process, safe operation and easy implementation.

[0005] In order to achieve the above purpose, the present invention provides the following technical solutions:

[0006] One of the technical solutions of the present invention is a method for directly mineralizing carbon dioxide by using magnesium reduction slag, spraying an acidic solution on the hot magnesium reduction slag, and then mixing it with flue gas for reaction;

[0007] The calcium ion concentration in the acidic solution is 650 - 800 mg / L, the H2O2 concentration is 20 - 180 mg / L, and the pH value is 3.4 - 4.2.

[0008] Another technical solution of the present invention is a device for implementing the above method for directly mineralizing carbon dioxide by using magnesium reduction slag, including a magnesium reduction slag pipeline 1, a water mist nozzle 2, a flue gas nozzle 3, a tail gas discharge device 4, a slag discharge device 5 and a mineralization reactor 6;

[0009] The magnesium reduction slag pipeline 1 and the water mist nozzle 2 are respectively located on both sides of the mineralization reactor 6, and both the magnesium reduction slag pipeline 1 and the water mist nozzle 2 are arranged in the reverse direction of the flue gas direction in the flue gas nozzle 3.

[0010] The present invention discloses the following technical effects:

[0011] The method for directly mineralizing and fixing carbon dioxide with magnesium reduction slag provided by the present invention utilizes the waste heat of hot magnesium slag for high-temperature direct mineralization, and blows acidic solution onto the hot magnesium slag to improve the mineralization efficiency.

[0012] The present invention improves the utilization efficiency of magnesium reduction slag. Moreover, the present invention has the characteristics of simple process, safe operation and easy implementation. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required to be used in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0014] Figure 1 It is a process schematic diagram of the method for directly mineralizing carbon dioxide with magnesium reduction slag in the present invention, wherein 1: magnesium reduction slag pipeline, 2: water mist nozzle, 3: flue gas nozzle, 4: tail gas discharge device, 5: slag discharge device, 6: mineralization reactor. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0015] Now, various exemplary embodiments of the present invention will be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, characteristics and implementation schemes of the present invention.

[0016] It should be understood that the terms described in the present invention are only for describing specific embodiments and are not used to limit the present invention. Additionally, for the numerical ranges in the present invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any intermediate value within any stated value or stated range, as well as each smaller range between any other stated value or intermediate value within the stated range, is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded from the range.

[0017] Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. Although this invention only describes preferred methods and materials, any methods and materials similar or equivalent to those described herein can also be used in the implementation or testing of this invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials related to the said documents. In case of conflict with any incorporated document, the content of this specification shall prevail.

[0018] Without departing from the scope or spirit of this invention, various improvements and changes can be made to the specific embodiments of the specification of this invention, which are obvious to those skilled in the art. Other embodiments obtained from the specification of this invention are obvious to those skilled in the art. The specification and examples of this invention are merely exemplary.

[0019] Regarding the use of "comprising", "including", "having", "containing", etc. in this article, they are all open-ended terms, meaning including but not limited to.

[0020] This invention directly mineralizes and fixes carbon dioxide by using the physical waste heat of magnesium reduction slag. The hot magnesium slag is sprayed with an acidic solution to increase the specific surface area of the magnesium reduction slag, enabling the magnesium reduction slag to react better with the flue gas, and then controlling the spraying angle of the flue gas to fully react with the magnesium reduction slag.

[0021] In the first aspect of this invention, a method for directly mineralizing carbon dioxide by using magnesium reduction slag is provided. An acidic solution is sprayed onto the hot magnesium reduction slag and then mixed with the flue gas for reaction.

[0022] The calcium ion concentration in the acidic solution is 650 - 800 mg / L, the H2O2 concentration is 20 - 180 mg / L, and the pH value is 3.4 - 4.2.

[0023] In some embodiments of this invention, the dosage of the acidic solution is: 50 - 75 kilograms of the acidic solution per ton of hot magnesium reduction slag.

[0024] In some embodiments of this invention, the carbon dioxide content in the flue gas is 10 - 25%, the water vapor content is 2 - 15%, and the sulfur dioxide content is 0 - 100 ppm; the flow rate of the flue gas is: the flue gas flow rate corresponding to each ton of hot magnesium reduction slag is 25 - 32 m 3 / h.

[0025] In the second aspect of this invention, a device for implementing the above method for directly mineralizing carbon dioxide by using magnesium reduction slag is provided, including a magnesium reduction slag pipeline 1, a water mist nozzle 2, a flue gas nozzle 3, a tail gas discharge device 4, a slag discharge device 5, and a mineralization reactor 6;

[0026] The magnesium reduction slag pipeline 1 and the water mist nozzle 2 are respectively located on both sides of the mineralization reactor 6, and both the magnesium reduction slag pipeline 1 and the water mist nozzle 2 are arranged in the reverse direction of the flue gas direction in the flue gas nozzle 3.

[0027] In some embodiments of the present invention, the included angle γ between the magnesium reduction slag pipeline 1 and the mineralization reactor 6 is 30 - 45°.

[0028] In some embodiments of the present invention, the material of the water mist nozzle 2 is alumina ceramic, zirconia ceramic or silicon carbide ceramic.

[0029] In some embodiments of the present invention, the pressure of the water mist nozzle 2 is 0.1 - 0.25 Mpa, and the sprayed mist droplet particles are 100 - 300 μm.

[0030] In some embodiments of the present invention, the pressure of the flue gas nozzle 3 is 20 - 45 kpa.

[0031] In some embodiments of the present invention, the magnesium reduction slag is fed into the mineralization reactor 6 through the magnesium reduction slag pipeline 1, and at the same time, the water mist nozzle 2 and the flue gas nozzle 3 are opened. The water mist nozzle 2 and the flue gas nozzle 3 respectively spray an acidic solution and flue gas into the mineralization reactor 6, and the magnesium reduction slag, the acidic solution and the flue gas react in the mineralization reactor. (As Figure 1 shown)

[0032] The present invention directly mineralizes carbon dioxide with hot magnesium reduction slag. By strictly controlling parameters such as the angle of the hot magnesium reduction slag pipeline, the pressure of the acidic solution and the nozzle, the particle size of the sprayed mist droplets, and the flue gas flow rate, a method for directly mineralizing and fixing carbon dioxide with magnesium reduction slag that is simple in process, safe in operation, and easy to implement is designed, which can improve the direct mineralization efficiency and the utilization rate of magnesium reduction slag, and has important significance in practical applications.

[0033] The technical solutions described in the present invention are all conventional solutions in the art unless otherwise specified. The reagents or raw materials used are all purchased from commercial channels or are publicly available unless otherwise specified.

[0034] To better understand the present invention, the content of the present invention will be further clarified below in conjunction with embodiments, but the content of the present invention is not limited to the following embodiments only.

[0035] In the embodiments, the waste heat of the hot magnesium reduction slag is used to mineralize carbon dioxide, and the waste heat temperature of the hot magnesium reduction slag is about 500 - 700 °C.

[0036] Example 1

[0037] In this embodiment, the calcium ion concentration in the acidic solution is 663 mg / L, the H2O2 concentration is 25 mg / L, the pH value is 4.1, and the dosage of the acidic solution is: 51.4 kilograms of acidic solution per ton of hot magnesium reduction slag; the carbon dioxide content in the flue gas is 13.2%, the water vapor content is 2.4%, and the sulfur dioxide content is 45 ppm.

[0038] The magnesium reduction slag (at a temperature of 625 °C) is fed into the mineralization reactor 6 through the magnesium reduction slag pipeline 1. At the same time, the water mist nozzle 2 and the flue gas nozzle 3 are opened. The water mist nozzle 2 and the flue gas nozzle 3 spray the acidic solution and the flue gas into the mineralization reactor 6 respectively. The magnesium reduction slag, the acidic solution and the flue gas react in the mineralization reactor; among them, the included angle γ between the magnesium reduction slag pipeline 1 and the mineralization reactor 6 is 33°; the injection pressure of the water mist nozzle 2 is 0.14 Mpa, the sprayed mist droplet particles are 275 μm, and the material is alumina ceramic; the pressure of the flue gas nozzle 3 is 25 kpa, and the flue gas flow rate is 204 m 3 / h (that is, the flue gas flow rate corresponding to each ton of hot magnesium reduction slag is 26 m 3 / h).

[0039] The direct mineralization efficiency of the magnesium reduction slag is 36.54%, and the magnesium oxide content is 2.84%.

[0040] Example 2

[0041] In this embodiment, the calcium ion concentration in the acidic solution is 724 mg / L, the H2O2 concentration is 64 mg / L, the pH value is 3.8, and the dosage of the acidic solution is: 63.4 kilograms of acidic solution per ton of hot magnesium reduction slag; the carbon dioxide content in the flue gas is 16.8%, the water vapor content is 4.5%, and the sulfur dioxide content is 24 ppm.

[0042] The magnesium reduction slag (at a temperature of 584 °C) is fed into the mineralization reactor 6 through the magnesium reduction slag pipeline 1. At the same time, the water mist nozzle 2 and the flue gas nozzle 3 are opened. The water mist nozzle 2 and the flue gas nozzle 3 spray the acidic solution and the flue gas into the mineralization reactor 6 respectively. The magnesium reduction slag, the acidic solution and the flue gas react in the mineralization reactor; among them, the included angle γ between the magnesium reduction slag pipeline 1 and the mineralization reactor 6 is 36°; the injection pressure of the water mist nozzle 2 is 0.21 Mpa, the sprayed mist droplet particles are 185 μm, and the material is zirconia ceramic; the pressure of the flue gas nozzle 3 is 30 kpa, and the flue gas flow rate is: 227 m 3 / h (that is, the flue gas flow rate corresponding to each ton of hot magnesium reduction slag is 29 m 3 / h).

[0043] The direct mineralization efficiency of the magnesium reduction slag is 39.16%, and the magnesium oxide content is 2.16%.

[0044] Example 3

[0045] In this embodiment, the calcium ion concentration in the acidic solution is 784 mg / L, the H2O2 concentration is 108 mg / L, the pH value is 3.5, and the dosage of the acidic solution is: 72.3 kg of acidic solution per ton of hot magnesium reduction slag; the carbon dioxide content in the flue gas is 21.5%, the water vapor content is 8.0%, and the sulfur dioxide content is 12 ppm.

[0046] The magnesium reduction slag (at a temperature of 687 °C) is fed into the mineralization reactor 6 through the magnesium reduction slag pipeline 1. At the same time, the water mist nozzle 2 and the flue gas nozzle 3 are opened. The water mist nozzle 2 and the flue gas nozzle 3 spray the acidic solution and the flue gas into the mineralization reactor 6 respectively. The magnesium reduction slag, the acidic solution and the flue gas react in the mineralization reactor; among them, the included angle γ between the magnesium reduction slag pipeline 1 and the mineralization reactor 6 is 41°; the injection pressure of the water mist nozzle 2 is 0.24 Mpa, the sprayed water mist droplet particles are 105 μm, and the material is silicon carbide ceramic; the pressure of the flue gas nozzle 3 is 42 kpa, and the flue gas flow rate is 243 m 3 / h (that is, the flue gas flow rate corresponding to each ton of hot magnesium reduction slag is 31 m 3 / h).

[0047] The direct mineralization efficiency of the magnesium reduction slag is 42.15%, and the magnesium oxide content is 1.76%.

[0048] Comparative Example 1

[0049] The difference from Example 3 is only that in the acidic solution, the calcium ion concentration is 900 mg / L and the H2O2 concentration is 200 mg / L, and the other steps and parameters are the same as those in Example 3.

[0050] The direct mineralization efficiency of the magnesium reduction slag is 31.1, and the magnesium oxide content is 3.32.

[0051] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A method for directly mineralizing carbon dioxide using magnesium reduction slag, characterized in that: Spraying an acid solution onto the hot magnesium reduction slag, and then mixing with the flue gas to react; The acidic solution has a calcium ion concentration of 650-800 mg / L, a H2O2 concentration of 20-180 mg / L, and a pH value of 3.4-4.

2.

2. The method for direct mineralization of carbon dioxide using magnesium reduction slag according to claim 1, characterized in that: The dosage of the acid solution is: 50-75 kg of acid solution per ton of hot magnesium reduction slag.

3. The method for direct mineralization of carbon dioxide using magnesium reduction slag according to claim 1, characterized in that: The carbon dioxide content in the flue gas is 10-25%, the water vapor content is 2-15%, and the sulfur dioxide content is 0-100ppm; the flow rate of the flue gas is: the flue gas flow rate corresponding to each ton of hot magnesium reduction slag is 25-32m 3 / h.

4. A device for implementing the method for directly mineralizing carbon dioxide using magnesium reduction slag according to any one of claims 1 to 3, characterized in that: It comprises a magnesium reduction slag pipeline (1), a water mist nozzle (2), a flue gas nozzle (3), an exhaust gas discharge device (4), a slag discharge device (5) and a mineralization reactor (6); The magnesium reduction slag pipeline (1) and the water mist nozzle (2) are respectively located on both sides of the mineralization reactor (6), and the magnesium reduction slag pipeline (1) and the water mist nozzle (2) are arranged in the opposite direction to the flue gas direction in the flue gas nozzle (3).

5. The device for implementing the method of directly mineralizing carbon dioxide using magnesium reduction slag according to claim 4, characterized in that: The angle γ between the magnesium reduction slag pipeline (1) and the mineralization reactor (6) is 30-45°.

6. The device for implementing the method of directly mineralizing carbon dioxide using magnesium reduction slag according to claim 4, characterized in that: The water mist nozzle (2) is made of alumina ceramics, zirconium oxide ceramics or silicon carbide ceramics.

7. The device for implementing the method of directly mineralizing carbon dioxide using magnesium reduction slag according to claim 4, characterized in that: The pressure of the water mist nozzle (2) is 0.1-0.25 MPa, and the spray droplet particles are 100-300 μm.

8. The device for implementing the method of directly mineralizing carbon dioxide using magnesium reduction slag according to claim 4, characterized in that: The pressure of the flue gas nozzle (3) is 20-45 kPa.

9. The device for implementing the method of directly mineralizing carbon dioxide using magnesium reduction slag according to claim 4, characterized in that: The magnesium reduction slag is fed into a mineralization reactor (6) through a magnesium reduction slag pipeline (1), and the water mist nozzle (2) and the flue gas nozzle (3) are turned on at the same time. The water mist nozzle (2) and the flue gas nozzle (3) respectively spray an acid solution and flue gas into the mineralization reactor (6), and the magnesium reduction slag, the acid solution and the flue gas react in the mineralization reactor.

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