Process for curing CO2 by using desulfurization slag

Abstract

The invention relates to the field of carbon dioxide capture, and discloses a process for curing CO2 by using desulfurization slag, which comprises the following steps: (1) drying and grinding SDS desulfurization slag, then contacting with coke oven gas for reaction to obtain a solid product, and mixing the obtained solid product with water to obtain a mixed solution; (2) the mixed solution obtained in the step (1) is in contact with metallurgical furnace flue gas for a first reaction, a reacted solution is obtained, the reacted solution is in contact with the metallurgical furnace flue gas for a second reaction, and a reacted material is obtained; and (3) carrying out reduced pressure evaporation and solid-liquid separation on the reacted material obtained in the step (2), and drying the solid-phase material obtained after solid-liquid separation to obtain sodium bicarbonate. According to the process, by reconstructing a desulfurization carbon sequestration synergistic harmless treatment process, synergistic treatment of metallurgical solid waste and CO2 is achieved, and Na2SO4 and Na2CO3 of desulfurization residues are converted into recycling products NaHCO3.

Description

Technical Field

[0001] The present invention relates to the field of carbon dioxide capture, and in particular to a process for solidifying CO2 using desulfurization slag. Background Art

[0002] At present, CO2 capture and solidification technologies mainly include saline layer and rock layer storage technology, metallurgical solid waste mineralization technology, biomass solidification technology, etc. Among them, the metallurgical solid waste mineralization technology is represented by steel slag mineralization technology, which can achieve solid waste disposal and CO2 solidification. The cost of carbon fixation of this technology is relatively low, and the solidified products can be exported as building materials.

[0003] However, in the metallurgical solid waste carbon fixation technology (steel slag carbon fixation), the free calcium oxide in the steel slag is mainly used to react with CO2 to generate CaCO3 to achieve CO2 solidification. The economic efficiency of carbon fixation in this process route is poor. The reason is that the free calcium oxide content in the metallurgical steel slag is low, the amount of CO2 that can be solidified is relatively small (about 80-100 mg / g), and the steel slag after carbon fixation is still a solid waste, and its use is relatively narrow.

[0004] The invention patent CN116771414B "Cooperative Management Method for CO2 Sequestration and Gas Hydraulicization in Coal Mine" discloses a method for CO2 sequestration and gas hydraulicization in coal seams in mines, which is carried out in the following steps: perforation-pre-injection-hole plugging-fracturing-water injection. The present invention introduces hot alkaline water from the mine into the pores of the coal seam that has been pre-injected with sufficient carbon dioxide, and uses the generated precipitation particles to achieve partial plugging of large pores; achieves repeated use of mine wastewater treatment; uses the blocked large pores to increase the water injection pressure in the coal seam, increase the permeability of the coal body, improve the gas extraction effect of the coal seam, recover high-concentration gas, and reduce the gas content in the mine air discharged into the atmosphere; achieves slow wetting of the coal body through unblocked small pores, reduces the dust content in the mine air discharged into the atmosphere, and constructs a technical system for green mineral resource utilization and environmental protection.

[0005] CN116749348A "A system and method for storing and utilizing CO2 in a concrete mixing station" discloses a system and method for storing and utilizing CO2 in a concrete mixing station. The system includes a pulping module, a circulating grinding module, and a storage application module. The circulating grinding module can grind the composite slurry prepared by the pulping module under CO2-containing gas and medium balls, and can recycle the CO2-containing gas to achieve continuous production of carbon mineralized slurry. The storage application module includes a connected storage bin and a mixer. The storage bin is used to receive and store the carbon mineralized slurry in the slurry bin, and the mixer is used to mix the carbon mineralized slurry to prepare commercial concrete. The present invention continuously peels off the surface of solid waste particles in the composite slurry through liquid phase grinding mechanical force, and increases CO2 and Ca through chemical dissolution promoting components. 2+The diffusion rate is very fast, which fully releases the carbonization potential of solid waste and shortens the carbonization time of traditional non-in-situ mineralization reaction from several hours to less than 40 minutes. The present invention not only consumes industrial solid waste, but also solidifies CO2 gas, realizing the utilization of CO2 as a glue material.

[0006] CN116902981A "A system and method for solidifying CO2 by adjusting the pH of the system" discloses a system and method for solidifying CO2 by adjusting the pH of the system, comprising a solid waste raw material input pipeline, an extraction reactor, a CO2 absorption tower, a carbon-rich flue gas input pipeline and a solid-liquid separator; the solid waste raw material input pipeline is connected to the inlet of the extraction reactor, the liquid outlet of the extraction reactor is connected to the liquid inlet of the CO2 absorption tower, and a gas outlet is provided on the top of the CO2 absorption tower; the carbon-rich flue gas input pipeline is connected to the flue gas inlet on the bottom side of the CO2 absorption tower, the slurry outlet at the bottom of the CO2 absorption tower is connected to the inlet of the solid-liquid separator, and the liquid outlet of the solid-liquid separator is connected to the liquid inlet of the extraction reactor. The system and method have the characteristics of simple process flow, high product economy and low cost.

[0007] CN116639933A "A method for preparing a paste for filling and solidifying CO2" discloses a method for preparing a paste for filling and solidifying CO2, comprising the following steps: taking raw materials by weight: 5-25 parts of cement, 5-25 parts of carbide slag, 25-45 parts of fly ash, 25-45 parts of coal gangue, pre-crushing the coal gangue, mixing the raw materials, adding water and stirring at a mass ratio of solid to water of 7:3, with a stirring speed of 80-100r / min, introducing high-purity CO2 into the stirred paste, and stirring it through a stirrer, introducing CO2 at a pressure of 0.1MPa, a stirring speed of 120-160r / min, and a stirring time of 1-2.5 hours. This scheme prepares a paste with relatively good flow properties, solidification properties and mechanical properties, and the prepared paste can be filled into the goaf of the mine, thereby achieving the goals of supporting the goaf, preventing surface subsidence, protecting the ecological environment, rationally utilizing solid waste, and reducing carbon emissions.

[0008] CN113321224B "A method for resource utilization of electrolytic manganese slag and solidification of CO2" discloses a method for resource utilization of electrolytic manganese slag and solidification of CO2, comprising the following steps: S100: Grind the electrolytic manganese slag and fly ash into powder and mix them evenly, press the powder into shape, and obtain a block mixture; S200: calcine the block mixture to generate and collect ammonia and SO3 gas respectively, the ammonia is used to prepare ammonia water, and the SO3 is used to prepare sulfuric acid, and the calcined residue is ground into powder; S300: fully mix the residue with water to form a slurry, filter to obtain a first filter residue and a first filtrate, and dry the first filter residue to obtain a cement admixture; S400: pass CO2 into the first filtrate obtained in step S300 to obtain vaterite calcium carbonate slurry, and obtain vaterite calcium carbonate after filtering and drying.

[0009] CN110078463B "A production process for manufacturing building blocks using steel slag to solidify CO2" discloses a production process for manufacturing building blocks using steel slag to solidify CO2, which relates to the field of environmental protection technology, and comprises: mixing aluminum ash with water, and hydrolyzing it at 80-100°C for 20-30 hours to obtain a solid-liquid mixture and ammonia, and filtering, drying, and crushing the solid-liquid mixture to obtain a dry product; mixing the dry product, papermaking white mud, and finished calcium aluminate powder to obtain a mixture; adding water to the mixture and placing it in a ball making machine to form spherical particles with a diameter of 1-1.5 cm, and then firing it at 1200-1350°C for 30-60 minutes to obtain the calcium aluminate powder and CO2; wherein the calcium aluminate powder is used to prepare a water purifier; CO2, steel slag and sand are reacted at 200-300°C and 1-1.5MPa for 3-8 hours to generate the building blocks. The present invention recycles CO2 and steel slag generated in the water purifier production process to produce building blocks, thereby effectively reducing the cost of the produced building blocks and having great economic, social and environmental benefits.

[0010] CN116764428A "A SDS dry desulfurization process with sodium bicarbonate recycling" discloses a SDS dry desulfurization process with sodium bicarbonate recycling. The coke oven flue gas passes through the desulfurization reactor and is sprayed with crushed sodium bicarbonate powder. After sufficient reaction, the flue gas enters the subsequent process section through bag dust removal and meets the discharge standards. The solid phase is intercepted by bag dust removal to obtain desulfurization slag. The desulfurization slag mainly contains sodium sulfate, sodium carbonate and a small amount of sodium chloride and organic matter. The desulfurization slag is catalytically thermally cracked to remove most of the organic pollutants, and sodium sulfite and sodium bicarbonate are completely converted into sodium sulfate and sodium carbonate. The catalytic cracking product is dissolved and impurities are removed to obtain refined brine. Weak acid is added to the refined brine for neutralization, and sodium bicarbonate and sodium sulfate are obtained respectively through multi-stage evaporation crystallization and solid-liquid separation devices. Sodium bicarbonate is dried to obtain a high-purity sodium bicarbonate product, which is reused as a raw material in the SDS dry desulfurization process, and sodium sulfate is sold as a product. The process of the present invention has low operating cost and simple operation, and realizes the concept of high-value recycling of SDS desulfurization slag and carbon emission reduction.

[0011] There are many methods for solidifying CO2. Many of them use metallurgical solid waste as carbon fixation raw materials, such as calcium carbide slag, electrolytic manganese slag, steel slag, etc., all of which use the free calcium oxide in them to react with CO2 for carbon fixation. And the resource products finally formed by the above technologies are mainly cement and construction raw materials, and no resource products with wide applications have been formed. Summary of the invention

[0012] The purpose of the present invention is to overcome the problems of low solidification rate of CO2 solidified by traditional metallurgical solid waste in the prior art, the inability to combine the carbon fixation process with the harmless disposal process, and the narrow utilization pathways of the products after carbon fixation, and to provide a process for solidifying CO2 with desulfurization slag. The process achieves coordinated management of metallurgical solid waste and CO2 by reconstructing the coordinated harmless treatment process of carbon fixation at the desulfurization site, and converts Na2SO4 and Na2CO3 in the desulfurization slag into the resource product NaHCO3.

[0013] In order to achieve the above object, the present invention provides a process for solidifying CO2 from desulfurized slag, the process comprising the following steps:

[0014] (1) drying and grinding the SDS desulfurization slag, and then contacting it with coke oven gas to react to obtain a solid product, and mixing the obtained solid product with water to obtain a mixed solution;

[0015] (2) contacting the mixed solution obtained in step (1) with metallurgical furnace fume to carry out a first reaction to obtain a reacted solution, and contacting the reacted solution with metallurgical furnace fume to carry out a second reaction to obtain a reacted material;

[0016] (3) subjecting the reacted material obtained in step (2) to reduced pressure evaporation and solid-liquid separation, and drying the solid phase material obtained after the solid-liquid separation to obtain sodium bicarbonate.

[0017] In step (1) of the present invention, the SDS desulfurization slag used comes from the by-product (waste desulfurizer) of the SDS dry desulfurization system for SO2 treatment of metallurgical furnace flue gas, which is a solid hazardous waste. Generally, the SDS desulfurization slag contains 50-60wt% Na2CO3 and 30-39wt% Na2SO4, and the rest is a small amount of dust and miscellaneous salts.

[0018] Furthermore, since there is a small amount of sodium sulfite and sodium bicarbonate in the SDS desulfurization slag, a drying process is required to convert the small amount of sodium sulfite and sodium bicarbonate into sodium sulfate and sodium carbonate. Under preferred circumstances, the drying conditions include: a temperature of 200-400°C (sodium sulfite cannot be converted into sodium sulfate if the temperature is too low, and a high temperature will result in high energy consumption of the system and affect the economy), and a time of 3-5h.

[0019] In step (1) of the present invention, the SDS desulfurization slag needs to be ground after drying, preferably to a particle size of ≤0.2 mm, because too large a particle size will affect the reaction performance of the desulfurization slag in a high-temperature reactor, resulting in incomplete conversion and other problems.

[0020] The coke oven gas used in the present invention is a purified clean gas produced in the coking process, mainly containing 50-60 vol% H2 and 20-30 vol% CH4, and a small amount of CO, CO2, N2, O2 and other hydrocarbons.

[0021] In step (1) of the present invention, coke oven gas is used as a reducing agent, and the coke oven gas is contacted with the SDS desulfurization slag obtained after grinding to react. The reaction is carried out under the condition of a catalyst. This process mainly converts sodium sulfate in the SDS desulfurization slag into sodium sulfide. The chemical reaction equation occurring in the reaction is as follows:

[0022] Na2SO4+4H2=Na2S+4H2O

[0023] In order to ensure that all Na2SO4 in the SDS desulfurization slag can be converted into Na2S, the H2 in the coke oven gas needs to be fed in excess according to the above chemical reaction equation, that is, the molar ratio of H2 in the coke oven gas to Na2SO4 in the SDS desulfurization slag is controlled to be greater than 4:1.

[0024] In step (1) of the present invention, the catalyst used in the reaction is an iron-based catalyst, and Fe2O3 is further selected; the reaction conditions include: a temperature of 550-650°C (too low a temperature will result in the sodium sulfate in the SDS desulfurization slag being unable to be completely converted into sodium sulfide, and too high a temperature will result in the formation of a eutectic between sodium sulfide and sodium sulfate, causing agglomeration, etc., which affects the reaction rate and product purity), and a time of 2-4 hours.

[0025] In step (1) of the present invention, the reaction is cooled after completion to obtain a solid product, the main components of which are sodium sulfide and sodium carbonate. The purpose of mixing the obtained solid product with water is to completely dissolve the sodium sulfide and sodium carbonate therein in water (the amount of water used can completely dissolve the sodium sulfide and sodium carbonate in the solid product), to obtain a mixed solution containing sodium sulfide and sodium carbonate, and then in the next step, the mixed solution is contacted with the flue gas of a metallurgical furnace to react (because the gas-liquid reaction rate is much higher than the gas-solid reaction rate, the solid product is mixed with water to obtain a mixed solution, which is convenient for the next step reaction).

[0026] Further in step (2), the metallurgical furnace flue gas used in the present invention is tail gas generated by the combustion of metallurgical coal gas, which contains 10-20 vol% CO2 and 70-80 vol% N2, as well as trace amounts (ppm level) of SO2 and NO x .

[0027] In step (2) of the present invention, the mixed solution obtained in step (1) is transported to a primary gas-liquid reactor, and then the metallurgical furnace flue gas is introduced, so that the mixed solution is contacted with the metallurgical furnace flue gas to carry out a first reaction, thereby obtaining a reacted solution; then the reacted solution is transported to a secondary gas-liquid reactor, so that it is contacted with the metallurgical furnace flue gas, and a certain amount of water is added (the first reaction is a gas-liquid reaction, which will take away a part of liquid water, and the reduction of water may cause the solute to precipitate, so it is necessary to add water to ensure that the solute will not precipitate, and the specific amount of water added is only required to ensure that the solute can be completely dissolved and will not precipitate), and a second reaction is carried out (two times of passing the metallurgical furnace flue gas to react can allow the components to be reacted in the mixed solution to be completely reacted), thereby obtaining a reacted material.

[0028] The primary gas-liquid reactor and the secondary gas-liquid reactor used in the present invention are both conventional gas-liquid reactors.

[0029] In the first reaction of step (2) of the present invention, sodium sulfide in the mixed solution is mainly used to absorb CO2 in the flue gas of the metallurgical furnace and convert it into sodium bicarbonate, wherein theoretically 1 mol of Na2S can absorb 2 mol of CO2. The main reaction equation occurring in the first reaction is as follows:

[0030] Na2S+2CO2+2H2O=2NaHCO3+H2S

[0031] Furthermore, in the first reaction, in order to absorb as much CO2 in the metallurgical furnace flue gas as possible, the CO2 in the metallurgical furnace flue gas introduced needs to be fed in excess according to the above chemical reaction equation, that is, the molar ratio of CO2 in the metallurgical furnace flue gas to Na2S in the mixed solution obtained in step (1) is controlled to be greater than 2:1.

[0032] The H2S gas produced in the first reaction can be transported to the coking Claus process through a pipeline to be used as a raw material for preparing high-purity sulfur.

[0033] In the second reaction of step (2) of the present invention, the sodium carbonate in the solution after the reaction is mainly used to absorb CO2 in the flue gas and convert it into sodium bicarbonate. Theoretically, 1 mol of Na2CO3 can absorb 1 mol of CO2. The main reaction equation occurring in the second reaction is as follows:

[0034] Na2CO3+CO2+H2O=2NaHCO3

[0035] Furthermore, in the second reaction, in order to absorb as much CO2 in the metallurgical furnace flue gas as possible, the CO2 in the metallurgical furnace flue gas introduced needs to be fed in excess according to the above chemical reaction equation, that is, the molar ratio of CO2 in the metallurgical furnace flue gas to Na2CO3 in the post-reaction solution is controlled to be greater than 1:1.

[0036] In the first reaction and the second reaction of step (2) of the present invention, the CO2 in the metallurgical furnace flue gas introduced is in an excess state, and the CO2 in the metallurgical furnace flue gas is captured by liquid; because the introduction of the metallurgical furnace flue gas at one time will lead to incomplete reaction, the metallurgical furnace flue gas is introduced twice, and the first reaction and the second reaction are carried out respectively, so that the components to be reacted in the mixed solution can fully react to capture the CO2 in the metallurgical furnace flue gas; wherein the first reaction mainly utilizes Na2S to absorb CO2 (the chemical reaction properties of Na2S determine that Na2S is the priority reaction), and some Na2CO3 may participate in the reaction, and the second reaction mainly utilizes Na2CO3 to absorb CO2.

[0037] In step (3) of the present invention, due to the use of reduced pressure evaporation technology, the sodium bicarbonate product obtained after drying has a high purity.

[0038] Further in step (3), the drying temperature is 40-50°C. When the drying temperature is higher than 50°C, sodium bicarbonate will gradually decompose. Therefore, it is more appropriate to control the drying temperature within the above range.

[0039] In a preferred case, the liquid phase material (waste liquid) obtained after solid-liquid separation in step (3) can be processed by a recovery solution purification system, and a portion can be returned to step (1) to be mixed with the solid product to obtain a mixed solution, and the other portion can be returned to step (2) to be used as water to be replenished in the second reaction.

[0040] The sodium bicarbonate product finally obtained in step (3) of the present invention can be recycled as a desulfurization raw material in the SDS desulfurization process, or can be directly exported as a product to further achieve resource recycling.

[0041] The use of SDS desulfurization slag, coke oven gas and metallurgical furnace flue gas in the technical solution of the present invention has the following advantages: 1. SDS desulfurization slag is a by-product of the SDS desulfurization process (solid hazardous waste), and generally enterprises outsource the treatment for a fee, and the main component of the SDS desulfurizer is sodium bicarbonate, and the product after desulfurization is sodium sulfate, which can eventually produce sodium bicarbonate by reacting with CO2, and can be recycled; and the SDS desulfurizer is purchased additionally during the desulfurization process of the enterprise. The present invention utilizes the waste desulfurizer to fix carbon and can also achieve its regeneration, which can effectively reduce the purchase amount of the desulfurizer, and at the same time treat the desulfurization waste slag, achieving multiple goals at one stroke; 2. Coke oven gas is a by-product gas of steel coking, which is abundant in the enterprise and is generally only used as fuel and is not fully utilized; the price within the metallurgical enterprise is very low, and it is economical; 3. Metallurgical furnace flue gas is waste gas generated in the steel smelting process, which is waste, has no cost, and can be seen everywhere in the metallurgical industry. The present invention further utilizes its waste, and at the same time fixes CO2 in the flue gas to reduce the carbon emissions of the enterprise.

[0042] The technical solution of the present invention has the following advantages:

[0043] 1. The present invention uses SDS desulfurization slag as the carbon fixation raw material. It uses sodium-based carbon fixation. The main components are Na2SO4 and Na2CO3, both of which participate in the CO2 solidification reaction. While fixing CO2, the desulfurization slag can be harmlessly disposed of to achieve the coordinated management of metallurgical solid waste and CO2. Compared with the traditional metallurgical solid waste carbon fixation process, it has the advantage of a large amount of solidified CO2. Theoretically, 1 mol of desulfurization slag can solidify 1.5-2 mol of CO2, which can effectively solve the current low solidification rate of CO2 solidified by metallurgical solid waste, the inability to combine the carbon fixation process with the harmless disposal process, and the narrow utilization path of the product after carbon fixation; this process completes the treatment of SDS desulfurization slag while achieving CO2 capture and solidification, and generates resource products. It has a broad application space and great promotion value.

[0044] 2. The present invention makes full use of the resources in the iron and steel metallurgical industry (coke oven gas, metallurgical furnace flue gas) to achieve the harmless disposal of SDS desulfurization slag, and replaces the sulfur element in the SDS desulfurization slag through coke oven gas (H2) and metallurgical furnace flue gas (CO2), solidifies the CO2 in the flue gas, and realizes the resource utilization of sulfur element by using downstream supporting processes; at the same time, Na2SO4 and Na2CO3 in the desulfurization slag are converted into resource product NaHCO3, which can be recycled as a desulfurization raw material in the SDS desulfurization process, and can also be directly exported as a product. It can be widely used in industrial fields such as chemical industry, medicine, food, light industry, textile, and people's daily life, with a wide range of uses, and can achieve resource reuse. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 It is a process flow chart of the present invention. DETAILED DESCRIPTION

[0046] The specific embodiments of the present invention are described in detail below in conjunction with the accompanying drawings. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0047] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0048] Example 1

[0049] like Figure 1 The process of solidifying CO2 from desulfurized slag shown comprises the following steps:

[0050] (1) SDS desulfurization slag (containing 59 wt% Na2CO3 and 38 wt% Na2SO4) was dried at 350°C for 4 h, cooled naturally to room temperature after drying, and then sent to a grinder to grind the material to a particle size of ≤0.2 mm, then 10 g of the ground material was sent to a high-temperature reactor, and coke oven gas (containing 56 vol% H2 and 27 vol% CH4) was introduced to make the ground material contact with excess coke oven gas (i.e., the molar ratio of H2 in the coke oven gas to Na2SO4 in the SDS desulfurization slag was controlled to be greater than 4:1) for reaction (the reaction was carried out in the presence of an iron-based catalyst Fe2O3, and the reaction conditions were: temperature of 600°C and time of 2 h), to obtain about 7.98 g of a solid product, and the obtained solid product was mixed with deionized water at a solid-liquid ratio of 1 g / 130 mL, so that Na2S and Na2CO3 in the solid product were completely dissolved in the deionized water to obtain a mixed solution;

[0051] (2) the mixed solution obtained in step (1) is sent to a primary reactor, and an excess of metallurgical furnace flue gas (containing 20 vol% CO2 and 74 vol% N2, and the molar ratio of CO2 in the metallurgical furnace flue gas to Na2S in the mixed solution obtained in step (1) is controlled to be greater than 2:1) is introduced, and the mixed solution is contacted with the metallurgical furnace flue gas for a first reaction to obtain a reacted solution, and the reacted solution is sent to a secondary reactor, and deionized water is added, and the mixed solution is contacted with an excess of metallurgical furnace flue gas (the molar ratio of CO2 in the metallurgical furnace flue gas to Na2CO3 in the reacted solution is controlled to be greater than 1:1) for a second reaction to obtain a reacted material;

[0052] (3) subjecting the reacted material obtained in step (2) to reduced pressure evaporation and solid-liquid separation, and drying the solid phase material obtained after solid-liquid separation at a drying temperature of 45° C., and finally obtaining about 13.84 g of high-purity sodium bicarbonate solid;

[0053] The liquid phase material obtained after solid-liquid separation in step (3) is processed by a recovery and purification system, and a portion is returned to step (1) to be mixed with the solid product to obtain a mixed solution, and the other portion is returned to step (2) to be used as deionized water to be supplemented in the second reaction;

[0054] Through mass balance calculation, in this embodiment, if the reaction is complete, the amount of CO2 that can be solidified is 480 mg / g, that is, 1 gram of SDS desulfurization slag can fix 480 mg of CO2, which has a good effect of solidifying CO2.

[0055] It should be understood that parts not elaborated in detail in this specification belong to the prior art.

[0056] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A process for solidifying CO2 from desulfurized slag, characterized in that: The process comprises the following steps: (1) drying and grinding the SDS desulfurization slag, and then contacting it with coke oven gas to react to obtain a solid product, and mixing the obtained solid product with water to obtain a mixed solution; (2) contacting the mixed solution obtained in step (1) with metallurgical furnace fume to carry out a first reaction to obtain a reacted solution, and contacting the reacted solution with metallurgical furnace fume to carry out a second reaction to obtain a reacted material; (3) subjecting the reacted material obtained in step (2) to reduced pressure evaporation and solid-liquid separation, and drying the solid phase material obtained after the solid-liquid separation to obtain sodium bicarbonate.

2. The process for solidifying CO2 from desulfurized slag according to claim 1, characterized in that: In step (1), the SDS desulfurization slag contains 50-60wt% of Na2CO3 and 30-39wt% of Na2SO4.

3. The process for solidifying CO2 from desulfurized slag according to claim 1 or 2, characterized in that: In step (1), the drying conditions include: temperature of 200-400° C. and time of 3-5 hours.

4. The process for solidifying CO2 from desulfurized slag according to claim 1 or 2, characterized in that: In step (1), the material is ground to a particle size of ≤0.2 mm.

5. The process for solidifying CO2 from desulfurized slag according to claim 1, characterized in that: In step (1), the coke oven gas contains 50-60 vol% H2 and 20-30 vol% CH4.

6. The process for solidifying CO2 from desulfurized slag according to claim 1 or 5, characterized in that: In step (1), the molar ratio of H2 in the coke oven gas to Na2SO4 in the SDS desulfurization slag is controlled to be greater than 4:

1.

7. The process for solidifying CO2 from desulfurized slag according to claim 1, characterized in that: In step (1), the reaction is carried out in the presence of a catalyst; The reaction conditions include: temperature of 550-650° C. and time of 2-4 h.

8. The process for solidifying CO2 from desulfurized slag according to claim 1, characterized in that: In step (2), the metallurgical furnace flue gas contains 10-20 vol% CO2 and 70-80 vol% N2.

9. The process for solidifying CO2 from desulfurized slag according to claim 1 or 8, characterized in that: In step (2), in the first reaction, the molar ratio of CO2 in the metallurgical furnace fume to Na2S in the mixed solution obtained in step (1) is controlled to be greater than 2:1; In the second reaction, the molar ratio of CO2 in the metallurgical furnace flue gas to Na2CO3 in the solution after the reaction is controlled to be greater than 1:

1.

10. The process for solidifying CO2 from desulfurized slag according to claim 1, characterized in that: In step (3), the drying temperature is 40-50°C.

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