Ammonia-ammonium chloride catalytic method system for decarburization of steel slag solid waste and flue gas

Abstract

The utility model discloses an ammonia-ammonium chloride catalysis system for decarburization of steel slag solid waste and flue gas, and belongs to the technical field of ferrous metallurgy. The ammonia-ammonium chloride catalysis system for steel slag solid waste and flue gas decarburization comprises a steel slag dissolving tank, an ammonia gas condensation cooler and a decarburization tower which are sequentially connected, the top of the decarburization tower is sequentially connected with an ammonia recovery system, an impurity filtering system and a calcium carbonate extraction system, and the bottom of the decarburization tower is connected with the calcium carbonate extraction system. The calcium carbonate extraction system is connected with the steel slag dissolving tank, and the steel slag dissolving tank is communicated with the ammonia recovery system. According to the technical scheme, the purpose of carbon capture and high-added-value resource reutilization of the steel slag are achieved.

Description

Technical Field

[0001] The utility model relates to the technical field of steel metallurgy, in particular to an ammonia-ammonium chloride catalytic system for decarbonizing steel slag solid waste and flue gas. Background Art

[0002] The field of iron and steel metallurgy produces large quantities of steel slag. Currently, the typical method for disposing of this solid waste is to simply treat the slag before incorporating it into cement clinker. However, this treatment method is not ideal because steel slag is highly alkaline, which can degrade cement performance. Furthermore, with the increasing adoption of green production, steel mills and other industrial manufacturers are facing environmental protection requirements.

[0003] Among flue gas decarbonization technologies, most publicly available include hot potash, organic amine, adsorption, and membrane separation. These technologies enrich carbon dioxide from flue gas, producing carbon dioxide with a purity exceeding 99%, which is then stored and disposed of. However, these carbon capture technologies consume a lot of energy and lack the ability to co-dispose of solid waste.

[0004] Ammonium chloride also has the chemical property of dissolving steel slag. Dissolving steel slag with ammonium chloride produces soluble products such as ammonia, calcium chloride, and magnesium chloride, which can be used to absorb carbon dioxide from flue gas. During this carbon dioxide absorption process, the ammonium chloride is regenerated, enabling recycling.

[0005] Therefore, it is necessary to design an ammonia-ammonium chloride catalytic system and process for decarbonizing steel slag solid waste and flue gas. Utility Model Content

[0006] The purpose of the utility model is to provide an ammonia-ammonium chloride catalytic system for decarbonizing steel slag solid waste and flue gas, so as to solve the problems raised in the above background technology.

[0007] To achieve the above objectives, the present invention provides the following technical solutions:

[0008] An ammonia-ammonium chloride catalytic system for decarbonizing steel slag solid waste and flue gas includes a steel slag dissolving tank, an ammonia condensation cooler and a decarbonization tower connected in sequence. The top of the decarbonization tower is connected in sequence to an ammonia recovery system, an impurity filtration system and a calcium carbonate extraction system. The bottom of the decarbonization tower is connected to the calcium carbonate extraction system, the calcium carbonate extraction system is connected to the steel slag dissolving tank, and the steel slag dissolving tank is connected to the ammonia recovery system.

[0009] As a further solution of the present invention: the ammonia recovery system includes an intermediate tank connected to the steel slag dissolving tank in sequence, an ammonia washing tower feed pump and an ammonia washing tower, and the ammonia washing tower is connected to the top of the decarbonization tower.

[0010] As a further solution of the present invention: the impurity filtration system includes a primary membrane separator connected to the bottom of the ammonia washing tower, the primary membrane separator is connected to the secondary membrane separator, and the secondary membrane separator is connected to the calcium carbonate extraction system.

[0011] As a further solution of the present invention: the calcium carbonate extraction system includes an acid gas decomposition tower connected to the bottom of the decarbonization tower, the top of the acid gas decomposition tower is connected to a carbon neutralization reactor, the bottom of the acid gas decomposition tower is sequentially connected to an ammonia feed pump, an ammonia distillation tower and a carbon neutralization reactor, and the carbon neutralization reactor is sequentially connected to an ammonium chloride solution pump and a steel slag dissolution tank.

[0012] As a further solution of the present invention: a decarbonization tower circulation pump is provided between the bottom and the top of the decarbonization tower.

[0013] As a further solution of the present invention, an ammonia water pump is provided between the ammonia condensation cooler and the decarbonization tower.

[0014] As a further solution of the present invention: an ammonia washing tower circulation pump is provided between the bottom and the top of the ammonia washing tower.

[0015] In summary, the beneficial effects of the utility model are as follows: using strongly alkaline steel slag, with the assistance of ammonia and ammonium chloride as catalysts, the steel slag is prompted to react with carbon dioxide to produce high-purity magnesium hydroxide and calcium carbonate products, which not only achieves the purpose of carbon capture, but also realizes the high-value-added resource recycling of steel slag. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a flow chart of the ammonia-ammonium chloride catalytic system for decarbonization of steel slag solid waste and flue gas.

[0017] In the figure: 1. Steel slag dissolving tank; 2. Ammonia condenser cooler; 3. Ammonia water tank; 4. Ammonia water pump; 5. Decarbonization tower; 6. Decarbonization tower circulation pump; 7. Ammonia scrubber; 8. Ammonia scrubber circulation pump; 9. Acid gas decomposition tower; 10. Ammonia water feed pump; 11. Ammonia distillation tower; 12. Primary membrane separator; 13. Secondary membrane separator; 14. Carbon neutralization reactor; 15. Ammonium chloride solution pump; 16. Ammonia scrubber feed pump; 17. Intermediate tank. DETAILED DESCRIPTION

[0018] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0019] Example

[0020] See also Figure 1 ,like Figure 1 As shown, an ammonia-ammonium chloride catalytic system for decarbonization of steel slag solid waste and flue gas comprises a steel slag dissolving tank 1, an ammonia condensation cooler 2 and a decarbonization tower 5 connected in sequence, an ammonia water pump 4 is provided between the ammonia condensation cooler 2 and the decarbonization tower 5, the top of the decarbonization tower 5 is connected in sequence to an ammonia recovery system, an impurity filtration system and a calcium carbonate extraction system, the bottom of the decarbonization tower 5 is connected to the calcium carbonate extraction system, a decarbonization tower circulation pump 6 is provided between the bottom and the top of the decarbonization tower 5, the calcium carbonate extraction system is connected to the steel slag dissolving tank 1, and the steel slag dissolving tank 1 is connected to the ammonia recovery system.

[0021] The ammonia recovery system includes an intermediate tank 17, an ammonia washing tower feed pump 16 and an ammonia washing tower 7 connected in sequence to the steel slag dissolving tank 1. An ammonia washing tower circulation pump 8 is provided between the bottom and the top of the ammonia washing tower 7. The ammonia washing tower 7 is connected to the top of the decarbonization tower 5.

[0022] The impurity filtering system includes a primary membrane separator 12 connected to the bottom of the ammonia washing tower 7, the primary membrane separator 12 is connected to a secondary membrane separator 13, and the secondary membrane separator 13 is connected to the calcium carbonate extraction system.

[0023] The calcium carbonate extraction system includes an acid gas decomposition tower 9 connected to the bottom of the decarbonization tower 5, the top of the acid gas decomposition tower 9 is connected to a carbon neutralization reactor 14, the bottom of the acid gas decomposition tower 9 is sequentially connected to an ammonia feed pump 10, an ammonia distillation tower 11 and a carbon neutralization reactor 14, and the carbon neutralization reactor 14 is sequentially connected to an ammonium chloride solution pump 15 and a steel slag dissolution tank 1.

[0024] The process of the ammonia-ammonium chloride catalytic method system for decarbonization of steel slag solid waste and flue gas includes the following steps:

[0025] S1. Mixing ammonium chloride solution and a certain amount of steel slag in a steel slag dissolving tank 1 and heating to 90°C, the steel slag dissolves and releases ammonia gas, and at the same time produces an acidic suspension containing solid magnesium hydroxide, solid ferric hydroxide, calcium chloride, and magnesium chloride. The pH value of the acidic suspension is less than or equal to 4.

[0026] The following chemical reactions occur in the slag dissolving tank:

[0027] ① Dissolution of steel slag:

[0028] CaO·SiO2+NH4Cl→CaCl2+NH3↑+SiO2↓

[0029] MgO·SiO2+NH4Cl→MgCl2+NH3↑+SiO2↓

[0030] Fe2O3+NH4Cl→FeCl3+NH3↑

[0031] Al2O3+NH4Cl→AlCl3+NH3↑

[0032] ②Hydrolysis reaction of ferric chloride and aluminum chloride:

[0033] FeCl3+H2O→Fe(OH)3+HCl(L)

[0034] AlCl3+H2O→Al(OH)3+HCl(L);

[0035] S2, the generated ammonia gas is condensed, cooled and washed in the ammonia condenser cooler 2, and converted into ammonia water with a concentration of 20%. The produced ammonia water is first transported to the ammonia water tank 3;

[0036] S3, ammonia water is sent into the decarbonization tower 5 by the ammonia water pump 4, and flue gas is input into the decarbonization tower 5 at the same time. Carbon dioxide in the flue gas reacts with ammonia water to generate ammonium bicarbonate, which then enters the acid gas decomposition tower 9 to generate ammonium bicarbonate reaction formula:

[0037] CO2+NH3→NH4HCO3;

[0038] S4. The acidic suspension is fed into the ammonia scrubber 7 by the ammonia scrubber feed pump 16. The flue gas after decarbonization enters the ammonia scrubber 7. The acidic suspension fully recovers the ammonia. The acidic suspension at the bottom of the ammonia scrubber 7 can be transferred to the top of the tower by the ammonia scrubber circulation pump 8 to achieve a thorough absorption. The following reactions occur in the ammonia scrubber:

[0039] HCl+NH3→NH4Cl

[0040] MgCl2+NH3+H2O→Mg(OH)2↓+NH4Cl;

[0041] S5, the suspension after absorbing ammonia enters the primary membrane separator 12 from the bottom of the ammonia scrubber 7, and an appropriate amount of ammonia water is added to adjust the pH value to 6-8, preferably, the pH value is 7, and the solid impurities of silicon dioxide, iron hydroxide, and aluminum hydroxide are filtered out;

[0042] S6, the filtrate of the primary membrane separator 12 enters the secondary membrane separator 13. At this time, the filtrate still contains a lot of soluble calcium and magnesium salts. At the same time, an appropriate amount of ammonia water is added to adjust the pH value to 9-11. The magnesium chloride in the filtrate undergoes hydrolysis reaction to obtain high-purity magnesium hydroxide. The following hydrolysis reaction occurs in the secondary membrane separator:

[0043] MgCl2+NH3+H2O→Mg(OH)2↓+NH4Cl;

[0044] S7, the ammonium bicarbonate entering the acid gas decomposition tower 9 decomposes into carbon dioxide gas and dilute ammonia solution. The carbon dioxide gas is released from the top of the acid gas decomposition tower 9 and enters the carbon neutralization reactor 14. The dilute ammonia solution is discharged from the bottom of the acid gas decomposition tower 9 and fed into the ammonia distillation tower 11 through the ammonia feed pump 10;

[0045] S8, the dilute ammonia solution is heated at high temperature in the ammonia distillation tower 11, ammonia is evaporated from the top of the tower and sent to the carbon neutralization reactor 14, and the wastewater at the bottom of the tower is sent to the wastewater treatment station;

[0046] S9. In the carbon neutralization reactor, calcium chloride in the filtrate reacts with ammonia and carbon dioxide to produce calcium carbonate and ammonium chloride solution. The ammonium chloride solution is also an ammonium salt solution. The ammonium chloride solution is returned to the slag dissolution tank 1 by the ammonium chloride solution pump 15. The following reaction occurs in the carbon neutralization reactor:

[0047] CO2+NH3+CaCl2→CaCO3↓+NH4Cl.

[0048] It should be noted that the above embodiments are only specific and clear descriptions of the technical solutions and technical features of the present application. For those skilled in the art, solutions or features that belong to the prior art or common knowledge will not be described in detail in the above embodiments.

[0049] In addition, the technical solutions of the present application are not limited to the above-mentioned embodiments. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

Claims

1. Ammonia-ammonium chloride catalytic system for decarbonization of steel slag solid waste and flue gas, characterized by: The invention comprises a steel slag dissolving tank (1), an ammonia condensation cooler (2) and a decarbonization tower (5) which are connected in sequence, wherein the top of the decarbonization tower (5) is connected in sequence to an ammonia recovery system, an impurity filtration system and a calcium carbonate extraction system, the bottom of the decarbonization tower (5) is connected to the calcium carbonate extraction system, the calcium carbonate extraction system is connected to the steel slag dissolving tank (1), and the steel slag dissolving tank (1) is connected to the ammonia recovery system.

2. The ammonia-ammonium chloride catalytic system for decarbonizing steel slag solid waste and flue gas according to claim 1, characterized in that: The ammonia recovery system comprises an intermediate tank (17) connected in sequence to the steel slag dissolving tank (1), an ammonia washing tower feed pump (16), and an ammonia washing tower (7), wherein the ammonia washing tower (7) is connected to the top of the decarbonization tower (5).

3. The ammonia-ammonium chloride catalytic method system for decarbonizing steel slag solid waste and flue gas according to claim 2, characterized in that: The impurity filtering system comprises a primary membrane separator (12) connected to the bottom of an ammonia washing tower (7), the primary membrane separator (12) being connected to a secondary membrane separator (13), and the secondary membrane separator (13) being connected to a calcium carbonate extraction system.

4. The ammonia-ammonium chloride catalytic method system for decarbonizing steel slag solid waste and flue gas according to claim 3, characterized in that: The calcium carbonate extraction system comprises an acid gas decomposition tower (9) connected to the bottom of a decarbonization tower (5); the top of the acid gas decomposition tower (9) is connected to a carbon neutralization reactor (14); the bottom of the acid gas decomposition tower (9) is sequentially connected to an ammonia feed pump (10), an ammonia distillation tower (11) and a carbon neutralization reactor (14); and the carbon neutralization reactor (14) is sequentially connected to an ammonium chloride solution pump (15) and a steel slag dissolution tank (1).

5. The ammonia-ammonium chloride catalytic method system for decarbonizing steel slag solid waste and flue gas according to claim 4, characterized in that: An ammonia water pump (4) is provided between the ammonia condensation cooler (2) and the decarbonization tower (5).

6. The ammonia-ammonium chloride catalytic method system for decarbonizing steel slag solid waste and flue gas according to claim 5, characterized in that: A decarbonization tower circulation pump (6) is provided between the bottom and the top of the decarbonization tower (5).

7. The ammonia-ammonium chloride catalytic method system for decarbonizing steel slag solid waste and flue gas according to claim 6, characterized in that: An ammonia scrubbing tower circulation pump (8) is provided between the bottom and the top of the ammonia scrubbing tower (7).

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