Method and device for analyzing smelting reduction reaction rate of material in high-temperature molten pool

Abstract

The invention provides a method and device for analyzing the smelting reduction reaction rate of a material in a high-temperature molten pool, and relates to the technical field of iron bath smelting reduction.The method comprises the steps that S1, iron powder and carbon powder are mixed to form an iron-carbon mixture, and the iron-carbon mixture is transferred into a container; s2, introducing the shielding gas flowing out of the reactor into a mass spectrometer; s3, heating the interior of the reactor to a target temperature, and turning on a material conveying switch of the reactor to convey the material into the container for reaction; and S4, observing gas mass data of the mass spectrometer, and calculating the limit conversion rate Vmax of the reduction reaction and the reaction duration tlast. The method is high in operability, good in raw material compatibility and high in field reducibility, effectively solves the problem that the high-temperature reaction of the small-particle-size materials is difficult to observe, and has important significance in characterizing the process of the smelting reduction reaction of the materials and constructing a kinetic model.

Description

Technical Field

[0001] The invention relates to the technical field of iron bath smelting reduction, in particular to a method and a device for analyzing the smelting reduction reaction rate of a material in a high-temperature molten pool. Background Art

[0002] The traditional blast furnace long process operation consumes a lot of resources and energy, and produces a lot of waste gas, waste water and waste slag due to processes such as coking and sintering, emitting hundreds of millions of tons of greenhouse gases, seriously polluting the environment. In contrast, the smelting reduction technology represented by the HIsmelt smelting reduction ironmaking process uses low-grade ore and non-coking coal as raw materials, reduces the cost of raw materials, does not require coking, sintering, pelletizing, and blast furnace processes, reduces carbon dioxide emissions, and significantly reduces environmental pollution generated by the production process of steel companies. It has become one of the most influential and investment-worthy non-blast furnace ironmaking processes under the "dual carbon strategy". The smelting reduction reaction is the core link of the HIsmelt technology, which has the characteristics of low fuel quality requirements and strong raw material applicability.

[0003] According to literature research, predecessors have used the rotating cylinder method, injection method, sampling analysis method and other methods to study the dissolution rate, reaction mechanism and influencing factors of materials such as iron ore in high-temperature melts. However, when studying the reaction laws of small-particle materials (6 mm and below), due to the extremely fast high-temperature melting reaction rate and easy explosion melting, and the reaction vessel is a closed container, it is difficult to capture the intermediate state of the reaction to study the heat transfer, expansion, explosion physical processes and element migration, iron oxide and carbon reduction and other chemical processes of the material. This particle size is the actual requirement for materials in the HIsmelt process production. Finding suitable research methods and characterization means to infer the reaction process is crucial.

[0004] In view of the above problems, the present invention aims to provide a new method for analyzing the molten reduction reaction rate of materials in a high-temperature molten pool. The method can utilize the CO and CO generated by the molten reduction of materials to generate 2 , H 2 The real-time content of gases and other data are used to calculate the reaction conversion rate, reaction conversion rate, reaction duration and other indicators, which effectively reflects the reaction process of the material in the iron bath molten pool, and provides a data basis for further exploring the reaction limiting links with kinetic methods and calculating kinetic parameters. The present invention has strong operability, good raw material compatibility, strong on-site reducibility, and effectively solves the problem that the high-temperature reaction of small-particle materials is difficult to observe. It is of great significance to characterize the process of material molten reduction reaction and construct a kinetic model. Summary of the invention

[0005] In order to solve the problems existing in the prior art, the present invention provides the following technical solution, which can collect tail gas data generated by molten reduction reaction of small-sized materials (including but not limited to iron ore powder, pellets and other metal ore powders, etc.) under different variable conditions (including but not limited to particle size, burnout, type, pre-reduction degree, quality, ore ratio and coal ratio, etc.) in an iron bath under different conditions (including but not limited to temperature, carbon content and ore-iron ratio, etc.) and perform kinetic analysis:

[0006] A method for analyzing the melting reduction reaction rate of a material in a high-temperature molten pool, comprising:

[0007] Step S1, mixing iron powder and carbon powder to form an iron-carbon mixture, transferring the iron-carbon mixture to a container, and transferring the container to a reactor; wherein the container can be a corundum crucible, and the reactor can be a sealable corundum tube.

[0008] Step S2, introducing a protective gas into the reactor, and introducing the protective gas flowing out of the reactor into the mass spectrometer; in this step, the furnace tube of the corundum tube is connected to the mass spectrometer through a rubber gas guide tube, and a protective gas (usually high-purity argon with a purity of 99.99%) is introduced into the reactor (corundum tube) at an appropriate flow rate, and then the mass spectrometer is turned on, and the gas flow rate is observed in a cold state to check the air tightness. If O 2 , CO 2 When the mass drops to 0 and becomes stable, it can be determined that the CO and CO absorbed by the mass spectrometer 2 All of them come from the reaction system in the crucible and have good airtightness.

[0009] Step S3, heating the reactor to the target temperature at a certain heating rate, to eliminate the influence of the original gas in the experimental environment on the experimental results, and wait until the mass spectrometer shows O 2 ,CO,CO 2 After the content decreases to 0 and becomes stable for a period of time, the material delivery switch of the reactor is turned on to deliver the material to the container for reaction.

[0010] Step S4: Observe the mass spectrometer CO, H 2 Gas quality data, after the data is stable for a period of time, the data recorded by the mass spectrometer is exported, and the reduction reaction limit conversion rate V is calculated after subtracting the gas baseline data before the S3 material enters the molten pool and starts to react. max , reaction duration t last .

[0011] Obviously, in order to ensure the accuracy of the conclusions obtained, the above steps can be repeated to retain data with high reproducibility under the same experimental conditions.

[0012] Preferably, the present invention processes the gas data obtained in step S4 as follows:

[0013] Step S41: Use H 2 Mass calculation: The mass of CO produced by the reduction reaction of crystal water;

[0014] Step S42: According to the formula Calculate the reduction conversion rate and draw the reduction conversion curve through the absolute oxygen loss curve, where is the reduction conversion rate, is the melting reduction at time t; and calculate the reaction duration t last ;

[0015] Step S43: derive the reduction conversion curve, draw the reduction conversion rate curve, and take the peak value of the reduction conversion rate (dα / dt) as the reduction reaction limit conversion rate V max .

[0016] The method of the present invention adopts the following reduction reaction evaluation index:

[0017] (1) Limiting conversion rate V max : Take the peak data of the reduction conversion rate curve in step five, that is, the highest value of the reduction conversion rate (dα / dt), which reflects the material heat transfer and initial interface reaction efficiency under this condition. The greater the limiting conversion rate, the higher the efficiency.

[0018] (2) Reaction duration t last The melting reduction time corresponding to the reduction conversion rate reaching 5% is defined as the melting reduction starting time t b The melting reduction time corresponding to the reduction conversion rate reaching 95% is defined as the melting reduction termination time t f ; Take the reaction duration t last =t b -t f , reflecting the overall time efficiency. The shorter the time, the higher the efficiency.

[0019] Preferably, in step S3, the heating rate is 5°C-10°C / min, and the target temperature is 1300-1500°C; to ensure the sealing of the reactor, cooling water is passed through the top and bottom of the reactor for cooling.

[0020] Preferably, the stabilization time in step S3 is not less than 30 seconds; and the stabilization time in step S4 is not less than 2 minutes.

[0021] Furthermore, the present invention provides a device for the above method, comprising:

[0022] Material conveying switch: when the switch is closed, the material is loaded into the upper part of the switch in advance; when the switch is opened, the material enters the iron bath at a certain initial velocity; the material conveying pipe is sealed at the top so that the gas enters the mass spectrometer only from the gas pipe; silicon-molybdenum rod, which has the function of heating and constant temperature; corundum crucible, which has the function of containing the iron bath molten pool and causing melting reduction reaction; thermocouple, which has the function of detecting and calibrating temperature; high-alumina brick, which has the function of supporting the corundum crucible; iron-carbon reaction raw materials; cooling water, which has the function of absorbing heat and protecting the furnace tube and furnace; mass spectrometer, which detects the instantaneous quality of tail gas; temperature and cooling water control system, which has the function of supplying and discharging cooling water; gas control system, which blows in an inert protector (high-purity argon) to ensure that the iron-carbon melt and materials are not oxidized and ensure the safety of the experiment;

[0023] A corundum tube is vertically installed inside the reactor, the top and bottom of the corundum tube are sealed, and the sealed section is connected to external cooling water; a high-aluminum brick is installed inside the corundum tube, and a corundum crucible is installed on the top of the high-aluminum brick; a silicon-molybdenum rod that can heat the corundum crucible installation section is installed outside the corundum tube, and the silicon-molybdenum rod is connected to a thermocouple; a material conveying pipe passes through the top seal to convey the material to the corundum crucible, and a material conveying switch is arranged on the material conveying pipe;

[0024] The gas inside the corundum tube is connected to the mass spectrometer through a gas delivery channel, and the reactor is further connected to a gas control system and a cooling water control system.

[0025] Preferably, the gas delivery channel is arranged on the top seal of the corundum tube; the mass spectrometer is used in conjunction with the thermogravimetric equipment to form a mass spectrometer and thermogravimetric system.

[0026] The beneficial effects brought about by the technical solution provided by the embodiment of the present invention include at least:

[0027] The present invention provides a method and device for analyzing the melting reduction reaction rate of a material in a high-temperature molten pool, which can collect CO and CO generated by the melting reduction reaction of the material entering the molten pool. 2 , H 2 Gas, by analyzing gas data to characterize the reaction process of materials in the iron bath molten pool, calculate the reaction conversion rate, reaction conversion rate, reaction duration and other indicators, effectively reflect the reaction process of materials in the iron bath molten pool, and provide a data basis for further exploring the reaction limiting links with kinetic methods and calculating kinetic parameters. The present invention has strong operability, good raw material compatibility, strong on-site reducibility, and effectively solves the problem that it is difficult to observe the high-temperature reaction of small-particle materials. It is of great significance to characterize the process of material molten reduction reaction and construct a kinetic model. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. 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 these drawings without creative work.

[0029] Figure 1 It is a schematic diagram of the device for analyzing the melting reduction reaction rate of materials in a high-temperature molten pool according to the present invention;

[0030] Among them, 1-material conveying switch, 2-material conveying pipe, 3-silicon molybdenum rod, 4-corundum crucible, 5-thermocouple, 6-high alumina brick, 7-reaction raw materials, 8-cooling water, 9-mass spectrometer and thermogravimetric system, 10-cooling water control system, 11-gas control system. DETAILED DESCRIPTION

[0031] The technical solution of the present invention is described below in conjunction with the accompanying drawings.

[0032] In the embodiments of the present invention, words such as "exemplarily" and "for example" are used to indicate examples, illustrations or explanations. Any embodiment or design described as "example" in the present invention should not be interpreted as being more preferred or more advantageous than other embodiments or designs. Specifically, the use of the word "example" is intended to present the concept in a specific way. In addition, in the embodiments of the present invention, the meaning expressed by "and / or" can be both, or it can be either of the two.

[0033] In the embodiments of the present invention, "image" and "picture" can sometimes be used interchangeably. It should be noted that when the difference between them is not emphasized, the meanings they want to express are the same. "of", "corresponding" and "corresponding" can sometimes be used interchangeably. It should be noted that when the difference between them is not emphasized, the meanings they want to express are the same.

[0034] In the embodiments of the present invention, sometimes the subscripts such as W 1 It may be mistakenly written as a non-subscript form such as W1. When the difference is not emphasized, the meanings they express are the same.

[0035] In order to make the technical problems, technical solutions and advantages to be solved by the present invention more clear, a detailed description will be given below with reference to the accompanying drawings and specific embodiments.

[0036] Example 1: Analysis of the smelting reduction characteristics of four materials: mineral powder 1#, 2#, 3#, and 4#

[0037] In order to explore the effect of material type on molten reduction behavior, the same temperature (1400℃), particle size (3-4mm), and carbon content of the molten pool (4wt%C) were controlled, and four materials, namely, mineral powders 1#, 2#, 3#, and 4#, were put into the Fe-C melt for molten reduction reaction. Before the experiment, a certain amount of reduced iron powder and a certain amount of chemically pure graphite (mass fraction of 99.99%) were weighed, fully mixed to form a 300g iron-carbon mixture, poured into a corundum crucible, and 1g of material was added to the iron bath molten pool. After the reaction, the tail gas data was derived and processed to obtain the limiting conversion rate and reaction duration, and the effect of the mineral powder type on the molten reduction reaction was observed. Each group of experiments was repeated twice to ensure that the results of the second test were the same as the first, to verify the repeatability of the experiment, and to eliminate contingency.

[0038] Study on the influence of different material types on smelting reduction characteristics

[0039]

[0040] (1) Limiting conversion rate V max :

[0041] 1#(4.0417% / s)>2#(3.9802% / s)>3#(3.9633% / s)>4#(3.9364% / s)

[0042] (2) Reaction duration t last :1#(48s)<2#(53s)<3#(57s)<4#(58s)

[0043] From the two evaluation indicators, it can be seen that the efficiency of heat transfer and interface reaction of iron ore powder 1# is higher than that of 2#, 3# and 4#, and the reaction time efficiency of 1# is higher than that of 2#, 3# and 4#. From the data, it can be observed that the reaction duration of 1g of the material is about 53±5s, and only 1# iron ore powder can react completely within 50s, indicating that the structure of 1# iron ore powder is loose and porous and easy to burst, and the iron-carbon melt can penetrate into the interior of the iron ore, increasing the contact area with C and the element migration rate. At the same time, CO gas is generated earlier, which promotes the stirring of the molten pool. In actual production, 1# material can be selected according to cost.

[0044] Example 2: Effect of molten pool carbon content on iron ore smelting reduction reaction

[0045] In order to explore the effect of the carbon content of the molten pool on the molten reduction behavior of the material, the same ore type (1#) and temperature (1400°C) were controlled, and iron ore powders of 1-2mm, 3-4mm, and 5-6mm were put into Fe-C melts with carbon contents of 3% and 4%, and reacted at 1400°C. Before the experiment, a certain amount of reduced iron powder and chemically pure graphite (mass fraction of 99.99%) were weighed, fully mixed to form a 300g iron-carbon mixture, poured into a corundum crucible, and 1g of material was added to the iron bath molten pool. After the reaction, the tail gas data was derived and processed to obtain the limiting conversion rate and reaction duration, and the effect of the carbon content of the molten pool on the molten reduction reaction was observed. Each group of experiments was repeated twice to ensure that the results of the second test were the same as the first, to verify the repeatability of the experiment, and to eliminate contingency.

[0046] Study on the influence of different molten pool carbon contents on the molten reduction characteristics of materials

[0047]

[0048] (1) Limiting conversion rate:

[0049] 1-2mm particle size V max : 4%wtC group 1 (4.2472% / s) > 3%wtC group 4 (4.0928% / s);

[0050] 3-4mm particle size V max : 4%wtC group 2 (4.2651% / s) >3%wtC group 5 (4.1152% / s);

[0051] 5-6mm particle size V max : 4%wtC group 3 (4.2119% / s) >3%wtC group 6 (4.0537% / s)

[0052] (2) Reaction duration:

[0053] 1-2mm particle size last : 4%wtC group 1 (45s) < 3%wtC group 4 (51s);

[0054] 3-4mm particle size last : 4%wtC group 2 (48s) < 3%wtC group 5 (54s);

[0055] 5-6mm particle size last : 4%wtC group 3 (50s) < 3%wtC group 6 (56s)

[0056] The data show that the limiting conversion rate of 4%wtC is higher than 3%wtC in each particle size group, indicating that increasing the carbon content of the molten pool accelerates the efficiency of the interfacial reduction reaction of the material; the reaction duration of 4%wtC is significantly shorter than 3%wtC in each particle size group, and the increase in the carbon content of the molten pool can improve the efficiency of the reduction reaction. From the iron-carbon phase diagram, it can be seen that the saturated concentration of carbon in the iron-carbon melt is 4.3%wtC. In actual production, the carbon content of the iron bath molten pool should be dynamically maintained at 4.3% and above as much as possible while saving costs to achieve the best reaction effect.

[0057] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A method for analyzing the molten reduction reaction rate of a material in a high-temperature molten pool, characterized in that: include: Step S1, mixing iron powder and carbon powder to form an iron-carbon mixture, transferring the iron-carbon mixture to a container, and transferring the container to a reactor; Step S2, introducing a protective gas into the reactor, and introducing the protective gas flowing out of the reactor into a mass spectrometer; Step S3, heating the interior of the reactor to the target temperature at a certain heating rate, and after the mass spectrometer shows that the contents of O2, CO, and CO2 are reduced to 0 and tend to be stable for a period of time, turning on the material delivery switch of the reactor to deliver the materials to the container for reaction; Step S4: observe the mass data of CO and H2 gas from the mass spectrometer, wait for the data to stabilize for a period of time, export the data recorded by the mass spectrometer, subtract the gas baseline data before the reaction, calculate the mass, volume and quality of the CO gas produced by the reaction, and calculate the reduction reaction limit conversion rate V max , reaction duration t last .

2. The method according to claim 1, characterized in that Repeat steps S1-S4 and retain the data with high reproducibility under the same experimental conditions.

3. The method according to claim 1, characterized in that The gas data obtained in step S4 is processed as follows: Step S41, using the mass of H2 to calculate the mass of CO produced by the reduction reaction of crystal water; Step S42, after eliminating the influence of CO generated by crystal water, collecting data through a mass spectrometer to draw a molten reduction CO instantaneous mass curve; Step S43, calculating the theoretical oxygen loss by analyzing the chemical composition of the material, subtracting the mass of O actually taken away by C, and drawing the absolute oxygen loss curve of molten reduction; Step S44: According to the formula Calculate the reduction conversion rate, draw the reduction conversion curve through the absolute oxygen loss curve; and calculate the reaction duration t last ; Step S45: derive the reduction conversion curve, draw the reduction conversion rate curve, and take the peak value of the reduction conversion rate (dα / dt) as the reduction reaction limit conversion rate V max .

4. The method according to claim 1, characterized in that: In step S3, the heating rate is 5°C / min, and the target temperature is 1300-1500°C; to ensure the sealing of the reactor, cooling water is passed through the top and bottom of the reactor for cooling.

5. The method according to claim 1, characterized in that: The stabilization time in step S3 is not less than 30 seconds; the stabilization time in step S4 is not less than 2 minutes.

6. A device for the method according to any one of claims 1 to 5, characterized in that: include: A corundum tube is vertically installed inside the reactor, the top and bottom of the corundum tube are sealed, and the sealed section is connected to external cooling water; a high-aluminum brick is installed inside the corundum tube, and a corundum crucible is installed on the top of the high-aluminum brick; a silicon-molybdenum rod that can heat the corundum crucible installation section is installed outside the corundum tube, and the silicon-molybdenum rod is connected to a thermocouple; a material conveying pipe passes through the top seal to convey the material to the corundum crucible, and a material conveying switch is arranged on the material conveying pipe; The gas inside the corundum tube is connected to the mass spectrometer through a gas delivery channel, and the reactor is further connected to a gas control system and a cooling water control system.

7. The device according to claim 6, characterized in that The gas delivery channel is arranged on the top seal of the corundum tube; the mass spectrometer is used in conjunction with the thermogravimetric device to form a mass spectrometer and thermogravimetric system.

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