Device and method for continuously producing Fe3C by adopting low-carbon-activity reducing gas and product

Abstract

The invention discloses a device and method for continuously producing Fe3C by adopting low-carbon-activity reducing gas and a product, and relates to the field of a technology for greatly reducing emission of carbon dioxide in the iron and steel industry and high-grade steel production raw materials. The device comprises a reaction furnace body, a furnace body cover, an objective table and a gas introduction pipeline, the reaction furnace body is of a cylindrical tubular structure, the furnace body cover is arranged at the top end of the reaction furnace body, and the objective table is arranged at the lower end of the reaction furnace body; a feeding pipeline is inserted into a central hole of the furnace body cover, and a hole is formed beside the feeding pipeline for placing a thermocouple; micropores are uniformly distributed in the objective table, so that a CO-CO2 mixed gas can be introduced into the reaction furnace body through the gas introduction pipeline at the lower part of the objective table. According to the method, Fe3C is stably produced by taking ferric oxide as a raw material and adopting low-carbon-activity reducing gas. The technological process is short, energy consumption is low, and innovation of the Fe3C production technology is achieved.

Description

Technical Field

[0001] The present invention relates to a technology for substantially reducing carbon dioxide emissions in the steel industry and the field of raw materials for advanced steel production, and in particular to a device, method and product for continuously producing Fe3C using a low-carbon activity reducing gas. Background Art

[0002] The use of the traditional blast furnace-converter steelmaking process has problems such as excessive carbon dioxide emissions and the exhaustion of mineral resources. In China, the amount of scrap steel generated each year continues to increase, and the current blast furnace-converter method of steel production produces a large amount of CO2. In order to solve these problems, steel companies have begun to consider the transition to electric furnace steelmaking. The electric furnace scrap steel melting method is widely regarded as the steelmaking method with the lowest carbon dioxide emissions at present, and has become the mainstream method of steelmaking in the United States and the European Union. However, high-grade steel products made using the blast furnace-converter method, such as steel sheets for automobiles, cannot be made using the electric furnace steelmaking method using scrap steel as the main raw material. When scrap steel is used as a raw material for electric furnace steelmaking, the accumulation of impurities such as Cu in steel products becomes a major problem, so an iron source that does not contain impurities such as reduced iron is needed to reduce the impurity concentration. Therefore, in order to make these high-grade steel products in electric furnaces, a new iron source is needed to replace scrap steel.

[0003] Fe3C (cementite) usually exists in the form of granules, flakes or meshes. It has stable chemical properties at room temperature and is not easy to self-ignite, so it can be safely transported and stored. In high-temperature molten steel, although it is affected by the temperature and composition of the molten steel, cementite can dissolve quickly. In actual production, it can be evenly dissolved in the molten steel by controlling the addition speed and temperature. The steel bath has many excellent properties such as balanced internal temperature and promotion of denitrification reaction. It is an ideal choice for scrap steel replacement materials. However, due to the thermodynamic instability of Fe3C, its stable industrial production has not yet been achieved. So far, Fe3C production has been suitable for CO-CO2 mixed gas with a carbon activity of more than 1000, which cannot inhibit carbon precipitation. This is also the main reason for the inability to stabilize production. Summary of the invention

[0004] In view of the above-mentioned shortcomings of the existing Fe3C production process, the purpose of the present invention is to provide a device, method and product for continuously producing Fe3C using a low-carbon activity reducing gas, and a method for stably producing Fe3C using iron oxide as a raw material and a low-carbon activity reducing gas. The process is short and has low energy consumption, realizing innovation in Fe3C production technology.

[0005] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0006] According to a first aspect of the technical solution of the present invention, there is provided a device for continuously producing Fe3C using a low carbon activity reducing gas, wherein the device comprises: a reaction furnace body, a furnace cover, a loading platform and a gas inlet pipeline,

[0007] Wherein, the reaction furnace body is a cylindrical tubular structure, with the furnace body cover disposed at the top and the loading platform disposed at the bottom;

[0008] The central opening of the furnace cover is used to insert the feed pipe, and the opening beside the feed pipe is used to place a thermocouple;

[0009] The stage has a plurality of micro-holes evenly distributed thereon, so that the CO-CO2 mixed gas can be introduced into the interior of the reaction furnace body through the gas introduction pipe connected to the lower part of the stage.

[0010] Here, the thermocouple is used to measure the charge temperature inside the reaction furnace during the experiment.

[0011] Furthermore, during the experiment, the mouth of the feed pipe was sealed with a silicone plug.

[0012] Furthermore, the reaction furnace body is a quartz tube, and the diameter of the quartz tube is 30 mm and the height is 600 mm.

[0013] Furthermore, the furnace body cover is a cover made of silicone material.

[0014] Furthermore, the main body of the reaction furnace body is provided with the gas outlet near the top end, and the material outlet is provided at the bottom end.

[0015] Furthermore, the diameter of the stage is the same as that of the reaction furnace body, which is 30 mm; the thickness is 5 mm, and a plurality of holes of 30-50 microns are evenly distributed on the surface.

[0016] In the prior art, the reduction reaction is mostly achieved by directly introducing gas, but due to the inhomogeneity of the gas, the reaction time is long and the reaction efficiency is low. Therefore, in order to solve the adverse effects of gas inhomogeneity on reaction time and efficiency, after theoretical analysis and experimental verification, the applicant combines the above thickness with the aperture and proposes the above device with a stage having multiple evenly distributed holes, so that the device can ensure that the gas flows smoothly and evenly to the furnace body on the one hand, and avoid the penetration and falling of solid-phase reactants on the other hand, thereby ensuring the highest reaction efficiency.

[0017] Furthermore, the height of the gas outlet near the furnace cover is 500-800 mm, preferably 500 mm. Here, the setting of this height can ensure the smooth discharge of the tail gas.

[0018] Furthermore, the lower end of the thermocouple is close to the surface of the charge.

[0019] Further, the discharge port is close to the inner bottom surface of the reaction furnace body. Here, the discharge port is close to the inner bottom surface of the reaction furnace body to ensure smooth discharge of the reacted materials.

[0020] Furthermore, the height between the lower end of the feed pipe and the inner bottom surface of the reaction furnace body is 550-1000 mm, preferably 600 mm.

[0021] Furthermore, the gas outlet is connected to a gas analyzer.

[0022] During the experiment, the gas concentration, flow rate and flow rate are adjusted by connecting a gas analyzer to measure the composition of the gas outlet. After the gas analyzer is connected to measure the composition, the initial set gas concentration, flow rate and flow rate are monitored and verified to be reasonable according to the composition, and the changes in the concentration of the gas components detected during the reaction are analyzed and adjusted.

[0023] According to a second aspect of the technical solution of the present invention, there is provided a method for continuously producing Fe3C using a low carbon activity reducing gas, the method being produced by the device according to any one of the above aspects, the method comprising the following steps:

[0024] Step 1: placing powdered iron oxide from the top to the bottom of the device through a feeding pipe and supported by the stage;

[0025] Step 2: introducing a CO-CO2 mixed gas into the reactor body through the gas introduction pipeline, and controlling the carbon activity of the mixed gas to be between 1.5 and 5;

[0026] Step 3: Control the temperature of the reaction furnace body to 700-750° C. and keep it warm for 60 minutes; during this process, stably control the gas flow rate and flow velocity;

[0027] Step 4: After the temperature of the reaction furnace body drops to room temperature, stop introducing the CO-CO2 mixed gas and release the reduction product Fe3C from the discharge port.

[0028] Furthermore, in step 2, the carbon activity of the mixed gas is 1.5 and 5.

[0029] Furthermore, in step 3, the flow rate of the mixed gas is 500 mL / min.

[0030] Furthermore, in step 3, the temperature is 700°C and 750°C.

[0031] According to a third aspect of the technical solution of the present invention, there is provided a Fe3C, wherein the Fe3C is prepared by the method according to any one of the above aspects.

[0032] The beneficial effects of the present invention are as follows:

[0033] Through the device pumping method in the technical solution of the present invention, the carbon concentration in the gas can be controlled, and a stable airflow can be contacted with the experimental sample for the experiment, and the carbon concentration of the gas during the reaction process can be controlled. Under this condition, the purpose of preparing Fe3C using low carbon activity gas is achieved, and stable and continuous preparation of Fe3C for industrial production can be achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0035] Figure 1 Schematic diagram of the structure of the device for continuously producing Fe3C using a low carbon activity reducing gas according to Example 1 of the present invention.

[0036] Figure 2 This is the XRD analysis diagram of Fe3C prepared by thermal reduction of powdered iron oxide in Example 1 of the present invention.

[0037] Figure 3 This is the XRD analysis diagram of Fe3C prepared by thermal reduction of powdered iron oxide in Example 2 of the present invention.

[0038] Figure 4 These are XRD analysis diagrams of samples prepared by reduction using low-temperature and high-carbon activity gases in Comparative Examples 1 and 2, respectively.

[0039] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0040] The following will be described clearly and completely in conjunction with the technical solutions in the embodiments. Obviously, the described embodiments 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 creative work are within the scope of protection of the present invention.

[0041] The present invention uses a low-carbon concentration CO-CO2 mixed gas to produce Fe3C products, which can stably produce high-purity Fe3C. The preparation process is simple and can stably provide a high-quality Fe source for the preparation of high-grade steel by the electric furnace process. In the face of environmental problems existing in the steelmaking process of the traditional blast furnace-converter method, the steel industry has gradually adopted the electric furnace steelmaking method. In order to manufacture high-grade steel, high-purity Fe3C is required to replace scrap steel. The invention uses a low-carbon concentration CO-CO2 mixed gas to produce Fe3C products, which not only realizes low-carbon metallurgy, but also stably provides raw materials for blast furnace smelting of high-grade steel.

[0042] Specifically, the technical solution of the present invention first provides a device for continuously producing Fe3C using a low-carbon activity reducing gas, wherein the device comprises: a reaction furnace body, a furnace cover, a stage and a gas inlet pipeline,

[0043] Wherein, the reaction furnace body is a cylindrical tubular structure, with the furnace body cover disposed at the top and the loading platform disposed at the bottom;

[0044] The central opening of the furnace cover is used to insert the feed pipe, and the opening beside the feed pipe is used to place a thermocouple;

[0045] The stage has evenly distributed micropores, so that the CO-CO2 mixed gas can be introduced into the interior of the reaction furnace body through the gas introduction pipe at the bottom of the stage.

[0046] In a preferred embodiment, the thermocouple is used to measure the temperature of the sample inside the reaction furnace during the experiment.

[0047] In a preferred embodiment, during the experiment, the mouth of the feed pipe is sealed with a silicone plug.

[0048] In a preferred embodiment, the reaction furnace body is a quartz tube with a diameter of 30 mm and a height of 600 mm.

[0049] In a preferred embodiment, the furnace cover is a cover made of silicone material.

[0050] In a preferred embodiment, the gas outlet is arranged near the top portion of the main body of the reaction furnace body, and the material outlet is arranged at the bottom end.

[0051] In a preferred embodiment, the stage is about 5 mm thick.

[0052] In a preferred embodiment, during the experiment, the gas concentration, flow rate and flow velocity are adjusted by measuring the composition of the gas outlet.

[0053] Example 1

[0054] like Figure 1As shown, the device reactor body used in this embodiment is a quartz tube 1 with a diameter of 30mm and a height of 600mm. A silicone cover is used on the upper end of the quartz tube to ensure sealing. The feed pipe 2 is inserted into the center opening of the cover, and a thermocouple 3 is placed in the opening next to the feed pipe. Thermocouple 3 measures the temperature of the sample during the experiment. During the experiment, the feed pipe opening is sealed with a silicone plug. The quartz tube body has a hole near the top part to insert the gas outlet 4, and the bottom opening is set as the discharge port 5. A breathable quartz stage 6 is set at the bottom of the quartz tube. The stage is about 5mm thick and has evenly distributed micropores, which can achieve uniform dispersion of gas while stabilizing the airflow and has a carrying function. During the experiment, the gas concentration and flow rate and other parameters are adjusted by measuring the composition of the gas outlet.

[0055] Using the above device, the Fe3C preparation method in this embodiment includes the following steps:

[0056] (1) placing powdered iron oxide 7 at the bottom of the device from the top through the feed pipe 2 and supported by the stage;

[0057] (2) mixing CO and CO2 mixed gas 8, and controlling the carbon activity of the mixed gas to 5;

[0058] (3) introducing the mixed gas into the device from bottom to top;

[0059] (4) Control the device temperature to 700°C and keep it warm for 60 minutes.

[0060] (5) After the system cools down to room temperature, the CO-CO2 mixed gas is turned off and the reduction product is released from the discharge port 5.

[0061] Example 2

[0062] Using the above device of Example 1, the Fe3C preparation method of this embodiment includes the following steps:

[0063] (1) placing powdered iron oxide 7 at the bottom of the device from the top through the feed pipe 2 and supported by the stage;

[0064] (2) mixing CO and CO2 mixed gas 8, and controlling the carbon activity of the mixed gas to 1.5;

[0065] (3) introducing the mixed gas into the device from bottom to top;

[0066] (4) Control the device temperature to 750°C and keep it at that temperature for 60 minutes.

[0067] (5) After the system cools down to room temperature, the CO-CO2 mixed gas is turned off and the reduction product is released from the discharge port 5.

[0068] Comparative Example 1

[0069] (1) placing powdered iron oxide at the bottom of the device through a feeding pipe from the top and supported by the stage;

[0070] (2) Mix CO and CO2 gases and control the carbon activity of the mixed gas to 5.0;

[0071] (3) introducing the mixed gas into the device from bottom to top;

[0072] (4) Control the device temperature to 550°C and keep it at that temperature for 60 minutes.

[0073] (5) After the system cools to room temperature, the CO-CO2 mixed gas is turned off and the reduction product is released from the discharge port.

[0074] Comparative Example 2

[0075] (1) placing powdered iron oxide at the bottom of the device through a feeding pipe from the top and supported by the stage;

[0076] (2) Mix CO and CO2 gases and control the carbon activity of the mixed gas to 10;

[0077] (3) introducing the mixed gas into the device from bottom to top;

[0078] (4) Control the device temperature to 700°C and keep it warm for 60 minutes.

[0079] (5) After the system cools to room temperature, the CO-CO2 mixed gas is turned off and the reduction product is released from the discharge port.

[0080] The product prepared in the example was characterized by structure

[0081] (1) XRD characterization

[0082] Figure 2 This is the XRD analysis diagram of Fe3C prepared by thermal reduction of powdered iron oxide in Example 1. The corresponding diffraction peaks of Fe3C in the sample can be indexed to Fe3C with a tetragonal structure (JCPDS No.89-7271), which indicates that the prepared product has a structural skeleton of Fe3C.

[0083] Figure 3 This is the XRD analysis diagram of Fe3C prepared by thermal reduction of powdered iron oxide in Example 2. The corresponding diffraction peaks of Fe3C in the sample can be indexed to Fe3C with a tetragonal structure (JCPDS No.89-7271), which indicates that the prepared product also has the structural skeleton of Fe3C.

[0084] Figure 4The XRD analysis diagrams of the samples prepared by reduction using low temperature (550°C in Comparative Example 1) and high carbon activity gas (carbon activity of 10 in Comparative Example 2) in Comparative Examples 1 and 2 respectively. The samples still do not show iron oxides. Although there is a peak of Fe3C in Comparative Example 2, it is very small and the reaction product is still mainly iron oxides.

[0085] In summary, the present invention provides a method for producing Fe3C by using a CO-CO2 mixed gas with low carbon activity to inhibit carbon precipitation. Using Fe3C as an iron source for an electric furnace requires a large amount of Fe3C, and for this purpose, continuous production of Fe3C is required. The present invention uses a device that can stably control gas concentration and flow rate to continuously and stably produce Fe3C, and proposes optimal conditions for stably producing Fe3C using CO-CO2 reducing gas.

[0086] The above description is only a preferred embodiment of the present invention, and does not limit the patent scope of the present invention. All equivalent structural changes made by using the contents of the present invention specification under the inventive concept of the present invention, or directly / indirectly applied in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A device for continuously producing Fe3C using a low carbon activity reducing gas, characterized in that: The device comprises: a reaction furnace body, a furnace cover, a loading platform and a gas inlet pipeline. Wherein, the reaction furnace body is a cylindrical tubular structure, with the furnace body cover disposed at the top and the loading platform disposed at the bottom; The central opening of the furnace cover is used to insert the feed pipe, and the opening beside the feed pipe is used to place a thermocouple; The stage has a plurality of micro-holes evenly distributed thereon, so that a CO-CO2 mixed gas can be introduced into the interior of the reaction furnace body through the gas introduction pipe at the bottom of the stage.

2. The device for continuously producing Fe3C using a low carbon activity reducing gas according to claim 1, characterized in that: The thermocouple is used to measure the temperature of the material sample inside the reaction furnace during the experiment.

3. The device for continuously producing Fe3C using a low carbon activity reducing gas according to claim 1, characterized in that: During the experiment, the mouth of the feed pipe was sealed with a silicone plug.

4. The device for continuously producing Fe3C using a low carbon activity reducing gas according to claim 1, characterized in that: The reaction furnace body is a quartz tube with a diameter of 30 mm and a height of 600 mm; the furnace body cover is a silicone cover; The diameter of the stage is the same as that of the reaction furnace body, the thickness is 5 mm, and a plurality of 30-50 micron holes are evenly distributed on the surface.

5. The device for continuously producing Fe3C using a low carbon activity reducing gas according to claim 1, characterized in that: The main body of the reaction furnace body is provided with the gas outlet near the top end, and the material outlet is provided at the bottom end.

6. The device for continuously producing Fe3C using a low carbon activity reducing gas according to claim 1, characterized in that: The gas outlet is connected to a gas analyzer, and the gas analyzer is used to measure the components of the gas outlet to adjust the gas concentration, flow rate and flow velocity.

7. A method for continuously producing Fe3C using a low carbon activity reducing gas, characterized in that: The method is produced by the device according to any one of claims 1 to 6, and the method comprises the following steps: Step 1: placing powdered iron oxide from the top to the bottom of the device through a feeding pipe and supported by the stage; Step 2: introducing a CO-CO2 mixed gas into the reactor body through the gas introduction pipeline, and controlling the carbon activity of the mixed gas to be between 1.5 and 5; Step 3: Control the temperature of the reaction furnace body to 700-750° C. and keep it warm for 60 minutes; during this process, stably control the gas flow rate and flow velocity; Step 4: After the temperature of the reaction furnace body drops to room temperature, stop introducing the CO-CO2 mixed gas and release the reduction product Fe3C from the discharge port.

8. The method for continuously producing Fe3C using a low carbon activity reducing gas according to claim 7, characterized in that: In step 2, the carbon activity of the mixed gas is 1.5 and 5.

9. According to the method for continuously producing Fe3C using a low carbon activity reducing gas according to claim 7, in said step 3, the flow rate of the mixed gas is 500 mL / min; and the temperature is 700°C and 750°C.

10. A Fe3C, characterized in that The Fe3C is prepared by the method according to any one of claims 7 to 9.

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