Method for preparing light calcium carbonate by indirect mineralization of steel slag with blast furnace gas and device thereof

Abstract

The application relates to a method for preparing light calcium carbonate by indirectly mineralizing steel slag with blast furnace gas and a device thereof, the device comprising: a carbon capture device, a heating device in communication with the carbon capture device, a steel slag leaching device, a carbonation device, a first filtering device and a second filtering device; the outlet of the first filtering device is in communication with the carbonation device; the method uses the combustion of the upgraded gas after carbon capture as a heat source to heat the leaching device, improves the leaching rate of alkaline earth metals in the steel slag leaching process, realizes the resource utilization of heat energy, and significantly improves the overall heat efficiency of the system; meanwhile, the leaching temperature is effectively improved through the heating mode; CO2 obtained through carbon capture and CO2-containing gas generated in the combustion and heat exchange process are concentrated and introduced into the carbonation device, so that the CO2 reacts with alkaline earth metals in the leaching solution to generate light calcium carbonate, and permanent solidification and resource utilization of the CO2 are realized.

Description

Technical Field

[0001] This application relates to the field of solid waste resource utilization technology, and in particular to a method and apparatus for preparing light calcium carbonate by indirectly mineralizing steel slag using blast furnace gas. Background Technology

[0002] Blast furnace gas is a major byproduct of the blast furnace ironmaking process, and its CO2 emissions account for about 70% of the total emissions from iron and steel smelting. Therefore, reducing the CO2 content in blast furnace gas is of great significance to achieving the carbon reduction target of the iron and steel industry.

[0003] Currently, carbon capture technology is the main method used to treat CO2 in blast furnace gas. This technology uses an alkanolamine solution as an absorbent and removes CO2 from the blast furnace gas through an absorption-high-temperature desorption process, thereby obtaining high-purity CO2 gas and a CO / N2 mixture with improved calorific value. Although this method can effectively achieve decarbonization and calorific value improvement of blast furnace gas, the large-scale utilization of captured CO2 still faces significant challenges.

[0004] Existing CO2 disposal methods mainly include oilfield enhanced oil recovery, geological sequestration, marine sequestration, and syngas production. However, these methods are generally limited by specific geological conditions, high transportation costs, and the long-term stability of CO2 storage, and have not yet formed a mature, economical, and sustainable large-scale application model. Therefore, the bottleneck of CO2 utilization after carbon capture has become a key issue restricting the promotion of this technology and the deep decarbonization of industries.

[0005] In view of this, it is necessary to design a method and apparatus for indirectly mineralizing steel slag using blast furnace gas to prepare light calcium carbonate, in order to solve the above problems. Summary of the Invention

[0006] This application provides a method and apparatus for preparing light calcium carbonate by indirectly mineralizing steel slag using blast furnace gas, in order to solve the current problem of how to develop a convenient, stable, and permanent carbon fixation method for CO2 resource utilization that combines the production characteristics of steel enterprises.

[0007] In a first aspect, this application provides an apparatus for indirectly mineralizing steel slag using blast furnace gas to prepare light calcium carbonate, comprising: a carbon capture device, a heating device, a steel slag leaching device, a carbonation device, a first filtration device, and a second filtration device. The carbon capture device, the heating device, the carbonation device, and the second filtration device are connected in sequence; the steel slag leaching device, the first filtration device, and the carbonation device are connected in sequence. The carbon capture device is connected to the carbonation device; the heating device is used to provide a heat source for the steel slag leaching device.

[0008] In some embodiments, the heating device includes a gas heat exchange channel surrounding the outer wall of the slag leaching device and a combustion chamber located at the bottom of the slag leaching device, wherein the gas heat exchange channel is in communication with the combustion chamber; A heat exchanger is installed inside the gas heat exchange channel, and the heat exchanger is arranged in a spiral upward ring around the outer wall of the steel slag leaching device.

[0009] In some embodiments, the first output port of the carbon capture device is connected to the inlet of the combustion chamber via a first pipe, the second output port of the carbon capture device is connected to the inlet of the carbonation device via a second pipe, the outlet of the gas heat exchange channel is connected to the inlet of the carbonation device via a third pipe, the steel slag leaching device is connected to the first filter via a fourth pipe, the first filter is connected to the carbonation device via a fifth pipe, and the carbonation device is connected to the second filter via a sixth pipe.

[0010] In some embodiments, the steel slag leaching apparatus includes: a leaching container for containing steel slag; a first stirring device disposed within the leaching container; and / or, The carbonation apparatus includes a carbonation container, a second stirring device disposed within the carbonation container; and / or, A first flow meter is installed on the first pipe; and / or, A second flow meter is installed on the second pipe; and / or, A third flow meter is installed on the third pipe; and / or, The inlet of the carbon capture device is connected to a seventh pipe, and a fourth flow meter is installed on the seventh pipe.

[0011] Secondly, this application provides a method for preparing light calcium carbonate by indirectly mineralizing steel slag using blast furnace gas, comprising the following steps: Carbon capture treatment of blast furnace gas yields upgraded gas and CO2 gas; The upgraded gas is burned to obtain heated gas; The residual gas is obtained after the heating gas is used to provide heat for the leaching treatment of steel slag; Steel slag is mixed with an alkaline reagent to perform steel slag leaching treatment, resulting in a leaching mixture. The leaching mixture is first filtered to obtain leaching solution and leaching residue; A carbon source is mixed with the leachate and subjected to carbonation treatment to obtain a calcium carbonate mixture; and... The calcium carbonate mixture is subjected to a second filtration to obtain light calcium carbonate.

[0012] In some embodiments, the carbon source includes any one or more of the residual gas and the CO2.

[0013] In some embodiments, the alkaline reagent includes an NH4Cl solution.

[0014] In some embodiments, the steel slag contains alkaline earth metal elements; the alkaline earth metal elements include at least Ca.

[0015] In some embodiments, the alkaline earth metal element may further include Mg.

[0016] In some embodiments, the upgrading gas includes at least CO.

[0017] The technical solutions provided in this application have the following advantages compared with the prior art: 1. The apparatus for indirectly mineralizing steel slag to prepare light calcium carbonate using blast furnace gas, provided in this application embodiment, includes: a carbon capture device, a heating device connected to the carbon capture device, a steel slag leaching device, a carbonation device connected to the heating device, a first filter device with its inlet connected to the steel slag leaching device, and a second filter device connected to the carbonation device; wherein, the outlet of the first filter device is connected to the carbonation device; the heating device is used to provide a heat source for the steel slag leaching device; thus, a suitable device can be provided for subsequent carbon reduction in the blast furnace and proper CO2 utilization. In subsequent applications, this design not only directly improves the heating efficiency and reaction stability of the steel slag leaching process, but also reduces system energy consumption through cascaded utilization of thermal energy, providing a key guarantee for the continuous, stable, and efficient operation of the entire "steel slag mineralization and CO2 fixation to prepare calcium carbonate" process.

[0018] 2. The method for preparing light calcium carbonate by indirect mineralization of steel slag using blast furnace gas provided in this application embodiment utilizes the combustion of the upgraded gas after carbon capture as a direct heat source to indirectly heat the leaching device. This method improves the leaching rate of alkaline earth metals such as calcium and magnesium during the steel slag leaching process while realizing the resource utilization of thermal energy, significantly improving the overall thermal efficiency of the system. Simultaneously, the combination of direct and indirect heating effectively increases the leaching temperature, thereby significantly increasing the leaching rate of alkaline earth metals such as calcium and magnesium in the steel slag, providing sufficient raw materials for the subsequent carbonation reaction. The CO2 obtained from carbon capture, as well as the CO2-containing gas generated during combustion and heat exchange, are centrally fed into the carbonation device, allowing CO2 to react with the alkaline earth metals in the leaching solution to generate light calcium carbonate, achieving permanent solidification and resource utilization of CO2. Some gases within the system (such as combustion flue gas and heat exchange tail gas) are reintroduced into the carbonation process, ultimately leaving only inert gas N2 for emission, simplifying the tail gas treatment process and improving the overall process integrity and environmental friendliness. This process provides a practical and feasible technical solution for the large-scale and resource-based co-processing of CO2 from blast furnace gas and steel slag in the steel industry, which helps steel companies achieve end-of-pipe carbon reduction and zero solid waste emissions. Attached Figure Description

[0019] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0020] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 A schematic diagram of the apparatus for preparing light calcium carbonate by indirect mineralization of steel slag using blast furnace gas, provided in this application, is shown. Figure Labels 1-Carbon capture device; 21-Gas heat exchange channel; 22-Combustion chamber; 31-Leaching container; 32-First stirring device; 41-Carbonization container; 42-Second stirring device; 5-First filtration device; 6-Second filtration device; 71-First pipeline; 711-First flow meter; 72-Second pipeline; 721-Second flow meter; 73-Third pipeline; 731-Third flow meter; 74-Fourth pipeline; 75-Fifth pipeline; 76-Sixth pipeline; 77-Seventh pipeline; 771-Fourth flow meter. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0023] Various embodiments of this application may exist in the form of a range. It should be understood that the description in the form of a range is merely for convenience and brevity and should not be construed as a rigid limitation on the scope of this application. Therefore, it should be considered that the range description has specifically disclosed all possible sub-ranges and single numerical values ​​within that range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges, such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and single numbers within the range, such as 1, 2, 3, 4, 5, and 6, regardless of the range. In addition, whenever a numerical range is indicated in this application, it means including any referenced number (fraction or integer) within the indicated range. Unless otherwise specified, all raw materials, reagents, instruments, and equipment used in this application can be purchased commercially or prepared by existing methods. In this application, unless otherwise stated, directional terms such as "upper" and "lower" specifically refer to the drawing directions in the accompanying drawings. In addition, in this application, the terms "comprising," "including," etc., mean "including but not limited to." In this application, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, without necessarily requiring or implying any actual relationship or order between these entities or operations. In this application, "and / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A alone, A and B simultaneously, or B alone. A and B can be singular or plural. In this application, "at least one" means one or more, and "more than one" means two or more. "At least one," "at least one of the following," or similar expressions refer to any combination of these items, including any combination of single or plural items. For example, "at least one of a, b, or c," or "at least one of a, b, and c," can both represent: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, and c can each be single or multiple.

[0024] like Figure 1As shown, this application provides an apparatus for indirectly mineralizing steel slag with blast furnace gas to prepare light calcium carbonate, comprising: a carbon capture device 1, a heating device connected to the carbon capture device 1, a steel slag leaching device, a carbonation device connected to the heating device, a first filter device 5 whose inlet is connected to the steel slag leaching device, and a second filter device 6 connected to the carbonation device. The outlet of the first filter device 5 is connected to the carbonation device; The heating device is used to provide a heat source for the steel slag leaching device.

[0025] The present invention provides a device for indirectly mineralizing steel slag using blast furnace gas to prepare light calcium carbonate, which can provide a suitable device for subsequent carbon reduction in blast furnace and proper CO2 disposal.

[0026] As an optional implementation, in this embodiment of the application, the heating device includes a gas heat exchange channel 21 surrounding the outer wall of the steel slag leaching device and a combustion chamber 22 located at the bottom of the steel slag leaching device, wherein the gas heat exchange channel 21 is connected to the combustion chamber 22. A heat exchanger is installed inside the gas heat exchange channel 21, and the heat exchanger is arranged in a spiral upward ring around the outer wall of the steel slag leaching device.

[0027] Thus, the core benefit of this heating device design, featuring a "bottom combustion chamber + outer wall spiral-shaped gas heat exchange channel," lies in its structurally efficient heat transfer and uniform distribution. In subsequent applications, this design not only directly improves the heating efficiency and reaction stability of the steel slag leaching process but also reduces system energy consumption through cascaded utilization of thermal energy, providing a crucial guarantee for the continuous, stable, and efficient operation of the entire "steel slag mineralization and CO2 fixation for calcium carbonate production" process.

[0028] As an optional implementation, in this embodiment of the application, the first output port of the carbon capture device 1 is connected to the inlet of the combustion chamber 22 through a first pipe 71, the second output port of the carbon capture device 1 is connected to the inlet of the carbonation device through a second pipe 72, the outlet of the gas heat exchange channel 21 is connected to the inlet of the carbonation device through a third pipe 73, the steel slag leaching device is connected to the first filter device 5 through a fourth pipe 74, the first filter device 5 is connected to the carbonation device through a fifth pipe 75, and the carbonation device is connected to the second filter device 6 through a sixth pipe 76.

[0029] As an optional implementation, in this embodiment of the application, the steel slag leaching device includes: a leaching container 31 for containing steel slag, and a first stirring device 32 disposed within the leaching container 31; The carbonation apparatus includes a carbonation container 41 and a second stirring device 42 disposed within the carbonation container 41.

[0030] As an optional implementation, in this embodiment of the application, in order to measure the flow rate of materials entering the reaction system in real time and accurately, a first flow meter 711 is provided on the first pipe 71, a second flow meter 721 is provided on the second pipe 72, and a third flow meter 731 is provided on the third pipe 73; the inlet of the carbon capture device 1 is connected to a seventh pipe 77, and a fourth flow meter 771 is provided on the seventh pipe 77.

[0031] As an optional implementation, in this embodiment of the application, the inlet end of the carbon capture device 1 is connected to an eighth pipe, and a fifth flow meter is installed on the eighth pipe.

[0032] The gas heat exchange channel 21 is connected to the combustion chamber 22 via a ninth pipe.

[0033] Based on a general inventive concept, embodiments of this application provide a method for preparing light calcium carbonate by indirectly mineralizing steel slag using blast furnace gas, comprising the following steps: Step 1: Carbon capture treatment is performed on the blast furnace gas to obtain upgraded gas and CO2 gas; Step 2: Combust the upgraded gas to obtain heated gas; Step 3: After using the heating gas to provide heat for the steel slag leaching treatment, residual gas is obtained; Step 4: Mix steel slag with alkaline reagent to perform steel slag leaching treatment to obtain leaching mixture; Step 5: Perform a first filtration on the leaching mixture to obtain leaching solution and leaching residue; Step 6: Mix the carbon source with the leachate and perform carbonation treatment to obtain a calcium carbonate mixture; Step 7: Perform a second filtration on the calcium carbonate mixture to obtain light calcium carbonate.

[0034] The method for preparing light calcium carbonate by indirect mineralization of steel slag using blast furnace gas provided in this application indirectly heats the leaching device by using the combustion of the upgraded gas after carbon capture as a direct heat source. This improves the leaching rate of alkaline earth metals such as calcium and magnesium during the steel slag leaching process while simultaneously realizing the resource utilization of thermal energy, significantly enhancing the overall thermal efficiency of the system. Furthermore, the combination of direct and indirect heating effectively increases the leaching temperature, thereby significantly increasing the leaching rate of alkaline earth metals such as calcium and magnesium in the steel slag, providing sufficient raw materials for the subsequent carbonation reaction. The CO2 obtained from carbon capture, as well as CO2-containing gases generated during combustion and heat exchange, are centrally fed into the carbonation device, allowing the CO2 to react with the alkaline earth metals in the leaching solution to generate light calcium carbonate, achieving permanent solidification and resource utilization of CO2. Some gases within the system (such as combustion flue gas and heat exchange tail gas) are reintroduced into the carbonation process, ultimately leaving only inert gas N2 for emission, simplifying the tail gas treatment process and improving the overall integrity and environmental friendliness of the process.

[0035] This process provides a practical and feasible technical solution for the large-scale and resource-based co-processing of CO2 from blast furnace gas and steel slag in the steel industry, which helps steel companies achieve end-of-pipe carbon reduction and zero solid waste emissions.

[0036] As an optional implementation, in this embodiment of the application, the carbon source includes any one or more of the residual gas and the CO2.

[0037] As an optional implementation, in the embodiments of this application, the alkaline reagent includes NH4Cl solution.

[0038] As an optional implementation, in some embodiments of this application, the steel slag contains alkaline earth metal elements; the alkaline earth metal elements include at least Ca.

[0039] As an optional implementation, in the embodiments of this application, the alkaline earth metal may further include Mg.

[0040] As an optional implementation, in this embodiment of the application, the upgrading gas includes at least CO; the upgrading gas may also include N2.

[0041] The N2 is discharged through the gas outlet of the carbonation device.

[0042] The present application is further illustrated below with reference to specific embodiments. Experimental methods in the following embodiments that do not specify specific conditions are generally determined according to national standards. If no corresponding national standard exists, then generally accepted international standards, conventional conditions, or conditions recommended by the manufacturer are followed.

[0043] Example 1 like Figure 1As shown, Example 1 provides an apparatus for indirectly mineralizing steel slag using blast furnace gas to prepare light calcium carbonate, comprising: a carbon capture device 1, a heating device connected to the carbon capture device 1, a steel slag leaching device, a carbonation device connected to the heating device, a first filter device 5 whose inlet is connected to the steel slag leaching device, and a second filter device 6 whose inlet is connected to the carbonation device. The heating device includes a gas heat exchange channel 21 surrounding the outer wall of the slag leaching device and a combustion chamber 22 located at the bottom of the slag leaching device; a heat exchanger is installed in the gas heat exchange channel 21, and the heat exchanger is arranged in a spiral upward ring around the outer wall of the slag leaching device. The steel slag leaching apparatus includes: a leaching container 31 for containing steel slag and a first stirring device 32; The carbonation apparatus includes a carbonation container 41 and a second stirring device 42; The second outlet of the first filter device 5 is used to discharge the leaching residue; The first outlet of the carbon capture device 1 is connected to the inlet of the combustion chamber 22 via a first pipe 71. The second outlet of the carbon capture device 1 is connected to the inlet of the carbonation device via a second pipe 72. The outlet of the gas heat exchange channel 21 is connected to the inlet of the carbonation device via a third pipe 73. The leaching container 31 is connected to the inlet of the first filter device 5 via a fourth pipe 74. The first outlet of the first filter device 5 is connected to the carbonation device via a fifth pipe 75. The outlet of the carbonation device is connected to the second filter device 6 via a sixth pipe 76.

[0044] A first flow meter 711 is installed on the first pipe 71, a second flow meter 721 is installed on the second pipe 72, and a third flow meter 731 is installed on the third pipe 73; the inlet of the carbon capture device 1 is connected to a seventh pipe 77, and a fourth flow meter 771 is installed on the seventh pipe 77; the inlet end of the carbon capture device 1 is connected to an eighth pipe, and a fifth flow meter is installed on the eighth pipe; the gas heat exchange channel 21 is connected to the combustion chamber 22 through a ninth pipe.

[0045] In addition, a method for preparing light calcium carbonate by indirectly mineralizing steel slag using blast furnace gas is also provided, comprising the following steps: Step 1: Use carbon capture device 1 to perform carbon capture treatment on blast furnace gas to obtain upgraded gas (which contains CO and N2) and CO2; Step 2: The separated upgraded gas is transported to the combustion chamber 22 through the first pipeline 71 to burn the upgraded gas and obtain heated gas; Step 3: The heating gas is transported to the gas heat exchange channel 21 through the ninth pipe, and the heating gas is used to provide heat to the leaching container 31 for steel slag leaching treatment. After the heat is provided, residual gas (CO2, N2) is obtained. Step 4, the leaching treatment in leaching container 31 includes: mixing steel slag containing Ca and Mg elements with NH4Cl solution to carry out steel slag leaching treatment to obtain leaching mixture; Step 5: The leaching mixture is transported to the first filter device 5 through the fourth pipe 74 for the first filtration to obtain leaching solution and leaching residue; Step 6: The CO2 from Step 1 is transported to the carbonation device through the second pipe 72, the residual gas from Step 2 is transported to the carbonation device through the third pipe 73, and the leachate is transported to the carbonation device through the fifth pipe 75; then the CO2 from Step 1, the residual gas from Step 2, and the leachate are mixed and carbonated in the carbonation device to obtain a calcium carbonate mixture. Step 7: The calcium carbonate mixture is conveyed to the second filter device 6 through the sixth pipe 76, and the calcium carbonate mixture is filtered a second time to obtain light calcium carbonate.

[0046] The remaining N2 is discharged through the gas outlet of the carbonation unit.

[0047] In summary, this invention provides a method and apparatus for indirectly mineralizing steel slag using blast furnace gas to prepare light calcium carbonate. The apparatus includes: a carbon capture device, a heating device connected to the carbon capture device, a steel slag leaching device, a carbonation device connected to the heating device, a first filter device with its inlet connected to the steel slag leaching device, and a second filter device connected to the carbonation device; wherein the outlet of the first filter device is connected to the carbonation device; the heating device is used to provide a heat source for the steel slag leaching device; thus, a suitable device can be provided for subsequent carbon reduction in the blast furnace and proper CO2 utilization. The heating device includes a gas heat exchange channel surrounding the outer wall of the steel slag leaching device and a combustion chamber located at the bottom of the device, with the gas heat exchange channel connected to the combustion chamber. A heat exchanger is installed within the gas heat exchange channel, arranged in a spiral ascending manner around the outer wall of the device. This "bottom combustion chamber + spiral surrounding gas heat exchange channel" design achieves efficient heat transfer and uniform distribution through its structure. In subsequent applications, this design not only directly improves the heating efficiency and reaction stability of the steel slag leaching process but also reduces system energy consumption through cascaded utilization of thermal energy, providing a crucial guarantee for the continuous, stable, and efficient operation of the entire "steel slag mineralization and CO2 fixation to prepare calcium carbonate" process. This method indirectly heats the leaching device by using the combustion of the upgraded gas after carbon capture as a direct heat source. This increases the leaching rate of alkaline earth metals such as calcium and magnesium during the steel slag leaching process while simultaneously achieving resource utilization of thermal energy, significantly improving the overall thermal efficiency of the system. Simultaneously, by combining direct and indirect heating methods, the leaching temperature is effectively increased, thereby significantly enhancing the leaching rate of alkaline earth metals such as calcium and magnesium in steel slag, providing sufficient raw materials for subsequent carbonation reactions. CO2 obtained from carbon capture, along with CO2-containing gases generated during combustion and heat exchange, are centrally fed into the carbonation unit, allowing CO2 to react with alkaline earth metals in the leaching solution to generate light calcium carbonate, achieving permanent solidification and resource utilization of CO2. Some gases within the system (such as combustion flue gas and heat exchange tail gas) are reintroduced into the carbonation process, ultimately leaving only inert gas N2 for emission, simplifying the tail gas treatment process and improving the overall process's integrity and environmental friendliness. This process provides a practical technical solution for the large-scale, resource-based co-processing of blast furnace gas CO2 and steel slag in the steel industry, helping steel enterprises achieve end-of-pipe carbon reduction and zero solid waste emissions.

[0048] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed in this application.

Claims

1. An apparatus for indirectly mineralizing steel slag using blast furnace gas to prepare light calcium carbonate, characterized in that, include: Carbon capture device, heating device, steel slag leaching device, carbonation device, first filtration device and second filtration device; The carbon capture device, the heating device, the carbonation device, and the second filtration device are connected in sequence; the steel slag leaching device, the first filtration device, and the carbonation device are connected in sequence. The carbon capture device is connected to the carbonation device; the heating device is used to provide a heat source for the steel slag leaching device.

2. The apparatus for indirectly mineralizing steel slag using blast furnace gas to prepare light calcium carbonate according to claim 1, characterized in that, The heating device includes a gas heat exchange channel surrounding the outer wall of the steel slag leaching device and a combustion chamber located at the bottom of the steel slag leaching device, wherein the gas heat exchange channel is connected to the combustion chamber; A heat exchanger is installed inside the gas heat exchange channel, and the heat exchanger is arranged in a spiral upward ring around the outer wall of the steel slag leaching device.

3. The apparatus for indirectly mineralizing steel slag using blast furnace gas to prepare light calcium carbonate according to claim 2, characterized in that, The first output port of the carbon capture device is connected to the inlet of the combustion chamber through a first pipe; the second output port of the carbon capture device is connected to the inlet of the carbonation device through a second pipe; the outlet of the gas heat exchange channel is connected to the inlet of the carbonation device through a third pipe; the steel slag leaching device is connected to the first filter device through a fourth pipe; the first filter device is connected to the carbonation device through a fifth pipe; and the carbonation device is connected to the second filter device through a sixth pipe.

4. The apparatus for indirectly mineralizing steel slag using blast furnace gas to prepare light calcium carbonate according to claim 3, characterized in that, The steel slag leaching apparatus includes: a leaching container for containing steel slag; a first stirring device disposed within the leaching container; and / or, The carbonation apparatus includes a carbonation container, a second stirring device disposed within the carbonation container; and / or, A first flow meter is installed on the first pipe; and / or, A second flow meter is installed on the second pipe; and / or, A third flow meter is installed on the third pipe; and / or, The inlet of the carbon capture device is connected to a seventh pipe, and a fourth flow meter is installed on the seventh pipe.

5. A method for preparing light calcium carbonate by indirectly mineralizing steel slag using blast furnace gas, characterized in that, Includes the following steps: Carbon capture treatment of blast furnace gas yields upgraded gas and CO2 gas; The upgraded gas is burned to obtain heated gas; The residual gas is obtained after the heating gas is used to provide heat for the leaching treatment of steel slag; Steel slag is mixed with an alkaline reagent to perform steel slag leaching treatment, resulting in a leaching mixture. The leaching mixture is first filtered to obtain leaching solution and leaching residue; A carbon source is mixed with the leachate and subjected to carbonation treatment to obtain a calcium carbonate mixture; and... The calcium carbonate mixture is subjected to a second filtration to obtain light calcium carbonate.

6. The method for preparing light calcium carbonate by indirectly mineralizing steel slag using blast furnace gas according to claim 5, characterized in that, The carbon source includes any one or more of the residual gas and the CO2.

7. The method for preparing light calcium carbonate by indirectly mineralizing steel slag using blast furnace gas according to claim 6, characterized in that, The alkaline reagent includes NH4Cl solution.

8. The method for preparing light calcium carbonate by indirectly mineralizing steel slag using blast furnace gas according to claim 7, characterized in that, The steel slag contains alkaline earth metal elements; the alkaline earth metal elements include at least Ca.

9. The method for preparing light calcium carbonate by indirectly mineralizing steel slag using blast furnace gas according to claim 8, characterized in that, The alkaline earth metal element may also include Mg.

10. The method for preparing light calcium carbonate by indirect mineralization of steel slag using blast furnace gas according to any one of claims 5 to 9, characterized in that, The upgrading gas includes at least CO.

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