Method for evaluating blast furnace iron ore-coke coupling reactivity

Abstract

The invention discloses a method for evaluating blast furnace iron ore-coke coupling reactivity, which comprises the following steps: recording and drawing a CO change curve according to real-time CO concentration in simulated reaction tail gas to obtain time T1 required for the CO concentration in the tail gas to reach a peak value in a constant temperature process at a certain temperature of 1000-1200 DEG C; continuing to heat at a constant temperature point of 1000-1200 DEG C, wherein the CO concentration reaches the peak value again and the interval time of the constant temperature point is T2 in the process that the molten slag iron passes through the material column layer and drips; the CO concentration peak value in the tail gas during the gasification reaction of the coke and CO2, the CO concentration peak value of the tail gas in the dripping process of the iron ore, and the CO concentration peak value of the tail gas in the dripping process of the iron ore, and the CO concentration peak value of the tail gas in the dripping process of the iron ore, and the CO concentration peak value of the tail gas in the dripping process of the iron ore, and the CO concentration peak value of the tail gas in the dripping process of the iron ore and the CO concentration peak value of the tail gas in the dripping process of the iron ore are not accurate in coke weighing after the reaction caused by iron ore erosion, adhesion to the surface layer of the coke and adsorption of dust particles to the hole wall of the coke. And the evaluation of the coke quality change (weightlessness) is distorted.

Description

Technical Field

[0001] The invention belongs to the technical field of blast furnace ironmaking, and in particular relates to a method for evaluating the coupling reactivity of blast furnace iron ore-coke. Background Art

[0002] As an important raw material in blast furnace ironmaking, coke plays an important role in the smooth operation and efficient smelting of blast furnaces. With the development of large-scale and intelligent blast furnaces, the requirements for coke quality and its evaluation, prediction and control are becoming higher and higher. At present, the evaluation of the hot performance of coke by enterprises is mainly based on the national standard GB / T 4000-2017 "Test Method for Reactivity and Post-Reaction Strength of Coke". This method is a gasification reaction of coke with 100% CO2 at 1100℃, which cannot represent the evolution behavior of coke in the entire process inside the blast furnace. In particular, the reaction temperature in this method only considers 1100℃, and does not consider the direct reduction reaction of molten iron ore and coke, which is not highly coupled with the actual reaction behavior of coke inside the blast furnace. In addition, the test method for iron ore performance GB / T 34211-2017 "Method for Determining the Dripping Performance of Iron Ore during High-Temperature Load Reduction" mainly examines the softening characteristics of iron ore, and does not focus on the reactivity and reaction behavior of coke. The coke column in GB / T 34211-2017 does not undergo a gasification reaction, and cannot simulate the dripping behavior of the coke column after the gasification reaction of the molten slag iron mineral in the actual blast furnace. In production, in order to pursue the stability and smooth operation of the blast furnace, it is often the case that high-quality metallurgical coke in GB / T 4000-2017 is blindly overused, wasting high-quality coking coal resources. In order to pursue low-cost raw materials, inferior coke is used to affect the air and liquid permeability of the blast furnace.

[0003] At present, there are no reports at home and abroad on the method of evaluating the ore-coke coupling reactivity in the blast furnace soft-melting dripping zone. Patents 201910631697.5 and 201910630782.X disclose devices and methods for measuring the performance of iron ore reduction soft melting dripping in a simulated blast furnace. The above patents mainly simulate the reaction process of coke and iron ore in reaction mixed gases of different concentrations by temperature control, and mainly measure the performance of iron ore, but do not involve the reaction changes of coke, nor consider the influence of coke factors on the ore-coke coupling reaction process; Patent 202311830621.8 discloses a measurement and evaluation method for the high-temperature degradation intensity and particle size degradation behavior of metallurgical coke, and mainly examines the change in particle size during the coke gasification reaction; Patent 202410322387.6 discloses a method for measuring the interaction index between coke and iron-containing charge for blast furnaces, and uses the high-temperature reaction of iron ore and coke to obtain the coke dissolution rate and the reduction degree of iron-containing charge, among which the coke melting loss rate is the overall change of coke after the reaction, and does not involve the reaction degree of coke in different reaction processes. In addition, Patents 202311319033.8 and 202311830621.8 simulate the high-temperature reaction of coke and iron ore through experimental high-temperature furnaces. The evaluation of coke is mainly limited to the weight loss (mass change) of coke after the entire reaction. Due to the adsorption and erosion of molten iron ore on coke under high temperature conditions, and the porous structure of coke, the slag iron minerals adsorbed and corroded into the internal pore structure of coke are not easy to separate from the coke. Therefore, the mass of the coke weighed after the reaction is distorted (actually the mass of coke and corroded slag iron), resulting in inaccurate evaluation indicators. In addition, the above patents cannot reflect the changes in the degree of reaction of coke during the entire heating and insulation process. Summary of the invention

[0004] The purpose of the present invention is to provide a method for evaluating the coupling reactivity of blast furnace iron ore-coke. Based on the three-phase reaction of gas, liquid and solid inside the blast furnace and the differential reaction conditions in different regions, the whole process is continuously simulated and reflected. The change in the reaction degree of coke through the blast furnace block state, the soft melting dripping zone and the central dead material column zone is reflected, so as to solve the problem of inaccurate weighing of coke after reaction caused by iron ore erosion and adhesion of the coke surface and dust particles adsorbing the coke pore wall, and then distorted evaluation of coke quality change (weight loss).

[0005] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0006] A method for evaluating the coupling reactivity of blast furnace iron ore-coke, comprising raw material pretreatment, charging, simulated reaction and evaluation, recording and drawing a CO change curve according to the real-time CO concentration in the simulated reaction tail gas, and obtaining the indirect reduction and direct reduction time of the iron ore in the simulated reaction process, as well as the maximum gasification reactivity and the maximum reduction degree of the iron ore molten dripping through the material column layer; the iron ore indirect reduction time refers to the time T1 required for the CO concentration in the tail gas to reach a peak value during a constant temperature process of a certain temperature between 1000 and 1200°C; the direct reduction time refers to the time T2 between the constant temperature point between 1000 and 1200°C when the CO concentration reaches a peak value again during the dripping process of the molten slag iron through the material column layer; the maximum gasification reactivity refers to the peak value of the CO concentration in the tail gas during the gasification reaction of coke and CO2, The maximum reduction degree of the molten iron ore dripping through the material column layer refers to the peak value of the tail gas CO concentration during the iron ore dripping process when the temperature is kept constant at a certain temperature between 1000 and 1200°C and then continued to rise.

[0007]

[0008] Furthermore, the raw material pretreatment includes sampling and preparation of coke samples and sampling and preparation of iron ore samples.

[0009] Furthermore, the iron ore in the raw material pretreatment includes any one of sintered ore, pelletized ore and lump ore.

[0010] Furthermore, the coke sample is sampled and prepared: a certain mass of coke is selected, and the foam coke and furnace head coke are completely discarded; the coke is crushed and drummed to form approximately spherical particles; the coke powder adhering to the coke block is sieved to remove the coke powder, and the sample is reduced and placed in a sealed container for later use.

[0011] Furthermore, iron ore sample sampling and preparation: for pelletized ore, test samples with a particle size similar to that of coke are obtained by screening, and the test samples are obtained by mixing and shrinking, and the samples are divided into equal parts and placed in sealed containers for later use; for natural lump ore or sintered ore, they are first screened out, and then the large particles are crushed, and then screened to obtain test samples with a particle size similar to that of coke, and the test samples are mixed and shrunk to obtain the test samples, and the samples are divided into equal parts and placed in sealed containers for later use.

[0012] Further, charging means mixing or layering coke and iron ore into a high-temperature reactor, and then placing the reactor in a high-temperature reactor. First, the reactor is embedded in a corundum support tube, and the base of the corundum support tube is fixed to the base of the lifting mechanism by bolts. A gas preheating corundum tube is built into the corundum support tube to form a gas preheating interlayer. The corundum tube is a hollow structure, thereby ensuring that the liquid slag drips along the coke column and the pores at the bottom of the reactor. Then, the reactor slowly enters the high-temperature reactor with the corundum support tube driven by the lifting mechanism. In order to prevent the dripping liquid slag from sticking to the slag iron crucible, fine sand or graphite paper can be laid inside the slag iron crucible. The bottom surface of the slag iron crucible contains slag and also has the function of gas diversion. After the reactor enters the high-temperature reactor, the rising base is clamped, and the bottom of the reactor is sealed under the action of the clamped bolts and sealing rings. The bottom of the reactor is a porous structure, and the pore size is smaller than the particle size of coke and iron ore. The porous structure makes it easy for liquid slag to drip along the holes at the bottom of the reactor after passing through the coke column. At the same time, the reaction gas enters from the gas inlet, and then enters the reactor along the corundum support tube and the bottom of the reactor to react with the iron ore and coke.

[0013] Furthermore, the simulation reaction is divided into three stages:

[0014] In the first stage, the electric furnace is heated up and nitrogen is introduced to prevent the coke from burning. When the temperature of the material layer reaches 1050℃, the carbon dioxide cylinder is opened for preheating to ensure the stable outflow of carbon dioxide. The temperature is raised to a certain temperature in the range of 1000-1200℃, and the introduction of nitrogen is stopped and replaced with carbon dioxide. The temperature is kept constant for a period of time in the range of 1000-1200℃. The coke is heated in a N2 atmosphere, and then CO2 is introduced while keeping the temperature. The coke and CO2 are gasified (CO2+C-2CO), and the generated CO reacts indirectly with the iron ore for reduction (3Fe2O3+CO-2Fe3O4+CO2, Fe3O4+CO-3FeO+CO2, FeO+CO-Fe+CO2), which mainly simulates the reaction of the blast furnace block belt.

[0015] In the second stage, after the first stage, nitrogen and carbon dioxide mixed gas is used, and the temperature is continued to rise to a certain temperature in the range of 1350-1550°C; in addition to the indirect reduction reaction in the first stage, the iron ore partially undergoes a direct reduction reaction with coke (3Fe2O3+C-2Fe3O4+CO2, Fe3O4+C-FeO+CO2, FeO+C-Fe+CO2), and the molten slag iron minerals and the metallic iron produced by the reduction flow through the reacted coke column and drip, simulating the blast furnace soft melting dripping zone reaction;

[0016] In the third stage, after the second stage, the second stage's highest temperature is kept constant for 30 to 60 minutes, nitrogen is introduced during the constant temperature process, heating is stopped after the constant temperature ends, and the temperature of the nitrogen lower material layer drops below 100°C. The difference between the actual temperature and the furnace temperature that should be reached should not exceed 5°C, and the temperature difference between the thermocouple at the center of the furnace top and the bottom of the crucible should not exceed 10°C. The fully molten liquid slag drips through the coke column layer to simulate the reaction of the dead column in the center of the blast furnace, and finally cools to room temperature under an inert atmosphere.

[0017] Furthermore, the simulated reaction and evaluation refers to the evaluation of the iron ore-coke coupling reactivity value calculated by the CO concentration in the tail gas and the reaction time.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] The present invention simulates the continuous iron ore-coke coupling reaction of coke and iron ore through the blast furnace block zone, soft melting dripping zone and central dead material column by controlling the temperature, reaction atmosphere and reaction time, thereby improving the matching of blast furnace coke evaluation with the actual reaction behavior inside the blast furnace, especially using the change of tail gas CO concentration with reaction time during the reaction process to evaluate the degree of iron ore-coke-CO2 reaction, effectively solving the problem of inaccurate weighing of coke after the reaction caused by iron ore erosion and adhesion to the coke surface and dust particles adsorbing the coke pore wall, and then distorting the evaluation of coke mass change (weight loss). In addition, the developed method for evaluating the degree of blast furnace iron ore-coke coupling reaction provides a test basis for the utilization of blast furnace coke, and simulates the high-temperature gasification reaction of coke inside the blast furnace under gas-liquid-solid coexistence conditions, and the continuous process of molten slag iron minerals penetrating the coke material column iron, directly providing technical indicators of the degree of blast furnace coke material column ore-coke coupling reaction. After the implementation of this technology, it can effectively avoid some blast furnaces from over-relying on high-quality metallurgical coke and over-increasing high-quality coking coal, thereby reducing the cost of coking coal blending and alleviating the contradiction between the increasing shortage of high-quality coking coal in my country and the increasingly high quality requirements of coke in large blast furnaces. On the other hand, according to the characteristics of iron ore, coke and other charges used in each blast furnace, it can provide technical parameters of high-temperature reaction of coke columns that are different from the thermal performance indicators of conventional coke, directly simulate and evaluate the weight loss rate and liquid permeability of blast furnace charge columns, and specifically adjust the raw material structure of the blast furnace to match the charge with the blast furnace, provide technical support for the smooth operation of the blast furnace, and reduce the coke ratio of the blast furnace, which is of great significance to promoting resource conservation and intensive utilization as well as energy conservation and emission reduction in the steel industry. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1This is a schematic diagram of the reactor installation structure. Among them, 1-reactor; 2-iron ore layer; 3-coke layer; 4-corundum support tube; 5-built-in gas preheating corundum tube; 6-gas preheating interlayer; 7-slag iron crucible; 8-dry fine sand or graphite paper; 9-bolts; 10-bottom surface of slag iron crucible; 11-base of lifting mechanism; 12-sealing ring; 13-air inlet.

[0021] Figure 2 This is the CO concentration change curve in the tail gas during the reaction between pellet ore and coke.

[0022] Figure 3 This is the CO concentration change curve in the tail gas during the reaction between sintered ore and coke.

[0023] Figure 4 This is the CO concentration change curve in the tail gas during the reaction between natural lump ore and coke. DETAILED DESCRIPTION

[0024] The present invention is described in more detail below through examples.

[0025] Embodiment 1:

[0026] A method for evaluating the coupling reactivity of blast furnace iron ore-coke includes raw material pretreatment, charging, simulated reaction and evaluation, specifically:

[0027] 1. Raw material pretreatment

[0028] 1.1 Coke sample sampling and preparation

[0029] Take 20kg of coke not less than 25mm, and completely discard the coke with large pores and honeycomb shape and the furnace head coke with black head and not completely gray. Crush the coke and tumble it to make spherical particles less than 12mm. Then use a 10mm sieve to sieve to remove the coke powder adhering to the coke block, and use a reducer to reduce the prepared 10-12mm spherical coke sample to 800g, and use the quartering method to divide the sample into four portions, each of which is not less than 120g, and put them into a sealed container for later use.

[0030] 1.2 Iron ore sample sampling and preparation

[0031] The pellets are sieved to obtain test samples with a particle size range of 10mm to 12mm, which are mixed and reduced to obtain the test samples for this test. The sample volume is not less than 300g, and the sample is divided into four parts by the quartering method, each part is not less than 50g, and is placed in a sealed container for later use.

[0032] 1.3 Sample drying

[0033] Place the pellets and coke samples in a digital display forced air drying oven at 105℃±5℃ and dry them for not less than 2h. After cooling to room temperature, move them into a dryer for later use.

[0034] 1.4 Sample preparation

[0035] Weigh 100g±1 pellet of coke sample, accurate to 0.1g. Weigh 40g±1 pellet of pellet sample, accurate to 0.1g.

[0036] 2. Loading

[0037] 2.1 Coke and pellets are loaded into the reactor

[0038] Weigh 100g±1 grain of dried coke, accurate to 1g, and place it in a reactor with the same number of coke grains in each layer inside the crucible. Then place 40g±1 grain of pellets on the upper surface of the coke particles to form an iron ore layer 2. Place 20g of coke on the pellets to form two coke layers 3. Add a sealing cover on the upper part of the reactor with a ventilation hole in the center of the sealing cover.

[0039] 2.2 Reactor loaded into high temperature reactor

[0040] The reactor after loading is placed in the high-temperature reaction furnace by first embedding the reactor 1 into the corundum support tube 4, and a slag iron crucible 7 is arranged at the center of the base 11 of the lifting mechanism. The base of the corundum support tube 4 is fixed on the base 11 of the lifting mechanism by bolts, and the slag iron crucible 7 is just at the center of the corundum support tube 4. The built-in gas preheating corundum tube 5 forms a gas preheating interlayer 6. The corundum tube is a hollow structure, which ensures that the liquid slag iron drips along the coke material column and the pores at the bottom of the reactor. The reactor 1 slowly enters the high-temperature reaction furnace with the corundum support tube 4 driven by the lifting mechanism. In order to prevent the dripping liquid slag iron from sticking to the slag iron crucible, fine sand or graphite paper 8 can be laid inside the slag iron crucible. The bottom surface 10 of the slag iron crucible contains slag iron and also has the function of gas diversion. After the reactor enters the high-temperature reaction furnace, the rising base is clamped, and the bottom of the reactor is sealed under the action of the clamped bolts 9 and the sealing ring 12. The bottom of the reactor is a porous structure, and the pore size is smaller than the particle size of coke and iron ore. The liquid slag iron passes through the coke material column and drips along the bottom hole of the reactor. At the same time, the reaction gas enters from the gas inlet 13, and then enters the reactor along the corundum support tube 4 and the bottom of the reactor 1 to react with the pelletized ore and coke.

[0041] 3. Simulation reaction and evaluation

[0042] In the first stage, the furnace is heated up and nitrogen is introduced at a flow rate of 1L / min to prevent coke from burning. When the temperature of the material layer reaches 1050℃, the carbon dioxide cylinder is opened for preheating to ensure the stable outflow of carbon dioxide; the temperature is raised to 1100℃, the nitrogen is stopped, and the flow rate of carbon dioxide is changed to 5L / min±0.1L / min, and the temperature is kept at 1100℃ for 2h. In this process, coke and CO2 are gasified (CO2+C—2CO), and the generated CO reacts indirectly with iron ore for reduction (3Fe2O3+CO—2Fe3O4+CO2, Fe3O4+CO—3FeO+CO2, FeO+CO—Fe+CO2), which mainly simulates the reaction of the blast furnace block belt;

[0043] In the second stage, after the first stage, a mixture of 1L / min nitrogen and 0.25Lmin carbon dioxide was introduced, and the temperature continued to rise to 1350°C. In addition to the indirect reduction reaction in the first stage, part of the molten iron ore and coke underwent direct reduction reaction (3Fe2O3+C—2Fe3O4+CO2, Fe3O4+C—FeO+CO2, FeO+C—Fe+CO2), and the molten slag iron minerals and the metallic iron produced by the reduction flowed through the coke column after the reaction and dripped, mainly simulating the blast furnace soft melting dripping zone reaction.

[0044] In the third stage, the temperature was kept constant at 1350℃ for 30min, and 1L / min nitrogen was introduced during the constant temperature process. After the constant temperature was completed, the heating was stopped, and the temperature of the material layer was reduced to below 100℃ by 1L / min nitrogen. The difference between the actual temperature and the furnace temperature to be reached should not exceed 5℃, and the temperature difference between the thermocouple at the center of the furnace top and the bottom of the crucible should not exceed 10℃. The temperature was kept constant under an inert atmosphere, and the fully molten liquid slag dripped through the coke column layer, mainly simulating the reaction of the dead column in the center of the blast furnace, and finally cooled to room temperature under an inert atmosphere.

[0045] Observe the CO concentration change curve in the exhaust gas ( Figure 2 ) reflects the test process. According to the real-time CO concentration in the tail gas, the CO change curve is recorded and drawn, and it is concluded that the indirect reduction time T1 of iron ore in the simulated reaction process is 195min, the direct reduction time T2 is 8min, and the maximum gasification reaction degree The maximum reduction degree of the molten iron ore is 38%. is 30%.

[0046] The experimental simulation test of the coupling reaction degree between pellet ore and coke is:

[0047]

[0048] Example 2

[0049] A method for evaluating the coupling reactivity of blast furnace iron ore-coke includes raw material pretreatment, charging, simulated reaction and evaluation, specifically:

[0050] 1. Raw material pretreatment

[0051] 1.1 Coke sample sampling and preparation

[0052] Take 20kg of coke not less than 25mm, and completely discard the coke with large pores and honeycomb shape and the furnace head coke with black head and not completely gray. Crush the coke and tumble it to make spherical particles less than 12mm. Then use a 10mm sieve to sieve to remove the coke powder adhering to the coke block, and use a reducer to reduce the prepared 10mm-12mm spherical coke sample to 800g, and use the quartering method to divide the sample into four portions, each of which is not less than 120g, and put them into a sealed container for later use.

[0053] 1.2 Iron ore sample sampling and preparation

[0054] First, the sintered ore is screened out of the part larger than 12mm and crushed to make it all pass through a 12mm sieve, then the part below 12mm is combined and sieved through a 10mm sieve to obtain a test sample of 10mm to 12mm. The sample is mixed and reduced to obtain the sample for this test. The sample weight is not less than 300g. The sample is divided into four parts by the quartering method, each part is not less than 50g, and is placed in a sealed container for later use.

[0055] 1.3 Sample drying

[0056] Place the sintered ore and coke samples in a digital display forced air drying oven at 105℃±5℃ and dry them for not less than 2h. After cooling to room temperature, move them into a dryer for later use.

[0057] 1.4 Sample preparation

[0058] Weigh 100g±1 grain of coke sample, accurate to 0.1g. Weigh 40g±1 grain of sintered ore sample, accurate to 0.1g.

[0059] 2. Loading

[0060] 2.1 Coke and sintered ore are loaded into the reactor

[0061] Weigh 100g±1 grain of dried coke, accurate to 1g, and then weigh 40g±1 grain of sintered ore. Mix the sintered ore and coke and load them into the reactor, i.e., mix the ore and coke. Add a sealing cover on the top of the reactor, and a ventilation hole is set in the center of the sealing cover.

[0062] 2.2 Reactor loaded into high temperature reactor

[0063] The reactor after loading is placed in the high-temperature reactor by first embedding the reactor 1 into the corundum support tube 4. A slag iron crucible 7 is arranged at the center of the base 11 of the lifting mechanism. The base of the corundum support tube 4 is fixed on the base 11 of the lifting mechanism by bolts, and the slag iron crucible 7 is just at the center of the corundum support tube 4. The corundum support tube 4 has a gas preheating corundum tube 5 built in, forming a gas preheating interlayer 6. The corundum tube is a hollow structure, thereby ensuring that the liquid slag iron drips along the coke material column and the bottom pores of the reactor. The reactor 1 slowly enters the high-temperature reactor with the corundum support tube 4 driven by the lifting mechanism. In order to prevent the dripping liquid slag iron from sticking to the slag iron crucible, fine sand or graphite paper 8 can be laid inside the slag iron crucible. The bottom surface 10 of the slag iron crucible contains slag iron and also has the function of gas diversion. After the reactor enters the high-temperature reactor, the rising base is clamped, and the bottom of the reactor is sealed under the action of the clamped bolts 9 and the sealing ring 12. The bottom of the reactor is a porous structure with a pore size smaller than the particle size of coke and iron ore. The liquid slag iron passes through the coke material column and drips along the holes at the bottom of the reactor. At the same time, the reaction gas enters from the air inlet 13, and then enters the reactor along the corundum support tube 4 and the bottom of the reactor 1 to react with the sintered ore and coke.

[0064] 3. Simulation reaction and evaluation

[0065] In the first stage, the furnace is heated up, and nitrogen with a flow rate of 1L / min±0.1L / min is introduced to prevent coke from burning. When the temperature of the material layer reaches 1050℃, the carbon dioxide cylinder is opened for preheating to ensure the stable outflow of carbon dioxide; the temperature is raised to 1200℃, and the nitrogen is stopped, and carbon dioxide with a flow rate of 5L / min±0.1L / min is introduced instead. The temperature is kept at 1200℃ for 2h. In this process, coke and CO2 are gasified (CO2+C—2CO), and the generated CO undergoes indirect reduction reaction with iron ore (3Fe2O3+CO—2Fe3O4+CO2, Fe3O4+CO—3FeO+CO2, FeO+CO—Fe+CO2), which mainly simulates the reaction of the blast furnace block belt;

[0066] In the second stage, after the first stage, a mixture of 1L / min nitrogen and 0.25Lmin carbon dioxide was introduced, and the temperature continued to rise to 1350°C; when the temperature reached 1350°C, 1L / min nitrogen was introduced, and the temperature continued to rise to 1500°C. In addition to the indirect reduction reaction of the first stage, part of the molten iron ore and coke underwent direct reduction reaction (3Fe2O3+C—2Fe3O4+CO2, Fe3O4+C—FeO+CO2, FeO+C—Fe+CO2), and the molten slag iron minerals and the metallic iron produced by the reduction flowed through the coke column after the reaction and dripped, mainly simulating the blast furnace soft melting dripping zone reaction;

[0067] In the third stage, the temperature is kept constant at 1550℃ for 30min. During the constant temperature process, 1L / min nitrogen is introduced. After the constant temperature is completed, the heating is stopped and the temperature of the material layer is reduced to below 100℃ by 1L / min nitrogen. The temperature is kept constant under an inert atmosphere. The fully molten liquid slag iron drips through the coke material column layer. The difference between the actual temperature and the furnace temperature to be reached should not exceed 5℃. The temperature difference between the thermocouple at the center of the furnace top and the bottom of the crucible should not exceed 10℃. It mainly simulates the reaction of the dead material column in the center of the blast furnace, and finally cools to room temperature under an inert atmosphere.

[0068] Observe the CO concentration change curve in the exhaust gas ( Figure 3 ) to reflect the test process. According to the real-time CO concentration in the tail gas, the CO change curve was recorded and drawn, and it was found that the indirect reduction time T1 of iron ore in the simulated reaction process was 298min, the direct reduction time T2 was 10min, and the maximum gasification reaction degree The maximum reduction degree of the molten iron ore is 29.5%. It is 24%.

[0069] The experimental simulation test of the coupling reaction degree of sintered ore and coke is:

[0070]

[0071] Example 3

[0072] A method for evaluating the coupling reactivity of blast furnace iron ore-coke includes raw material pretreatment, charging, simulated reaction and evaluation, specifically:

[0073] 1. Raw material pretreatment

[0074] 1.1 Coke sample sampling and preparation

[0075] Take 20kg of coke not less than 25mm, and completely discard the coke with large pores and honeycomb shape and the furnace head coke with black head and not completely gray. Crush the coke and tumble it to make spherical particles less than 12mm. Then use a 10mm sieve to sieve to remove the coke powder adhering to the coke block, and use a reducer to reduce the prepared 10mm-12mm spherical coke sample to 800g, and use the quartering method to divide the sample into four portions, each of which is not less than 120g, and put them into a sealed container for later use.

[0076] 1.2 Iron ore sample sampling and preparation

[0077] First, the natural lump ore is screened out for the part larger than 12mm and crushed so that all of it passes through a 12mm sieve. Then the part below 12mm is combined and sieved through a 10mm sieve to obtain a test sample of 10mm to 12mm. The sample is mixed and reduced to obtain the sample for this test. The sample weight is not less than 300g. The sample is divided into four portions using the quartering method, each portion is not less than 50g, and is placed in a sealed container for later use.

[0078] 1.3 Sample drying

[0079] Place the natural lump ore and coke samples in a digital display forced air drying oven at 105℃±5℃ and dry them for not less than 2h. After cooling to room temperature, move them into a dryer for later use.

[0080] 1.4 Sample preparation

[0081] Weigh 100g±1 grain of coke sample, accurate to 0.1g. Weigh 40g±1 grain of natural lump ore sample, accurate to 0.1g.

[0082] 2. Loading

[0083] 2.1 Coke and natural lump ore are loaded into the reactor

[0084] Weigh 100g±1 grain of dried coke, accurate to 1g, and place it in a reactor. The number of coke grains in each layer inside the crucible is the same. Then, place 40g±1 grain of natural lump ore on the upper surface of the coke particles to form an iron ore layer 2. Place 20g of coke on the natural lump ore, that is, there are two coke layers 3. Add a sealing cover on the top of the reactor, and a ventilation hole is provided in the center of the sealing cover.

[0085] 2.2 Reactor loaded into high temperature reactor

[0086] The reactor after loading is placed in the high-temperature reaction furnace by first embedding the reactor 1 into the corundum support tube 4, and a slag iron crucible 7 is arranged at the center of the base 11 of the lifting mechanism. The base of the corundum support tube 4 is fixed on the base 11 of the lifting mechanism by bolts, and the slag iron crucible 7 is just at the center of the corundum support tube 4. The built-in gas preheating corundum tube 5 forms a gas preheating interlayer 6. The corundum tube is a hollow structure, which ensures that the liquid slag iron drips along the coke material column and the pores at the bottom of the reactor. The reactor 1 slowly enters the high-temperature reaction furnace with the corundum support tube 4 driven by the lifting mechanism. In order to prevent the dripping liquid slag iron from sticking to the slag iron crucible, fine sand or graphite paper 8 can be laid inside the slag iron crucible. The bottom surface 10 of the slag iron crucible contains slag iron and also has the function of gas diversion. After the reactor enters the high-temperature reaction furnace, the rising base is clamped, and the bottom of the reactor is sealed under the action of the clamped bolts 9 and the sealing ring 12. The bottom of the reactor is a porous structure, and the pore size is smaller than the particle size of coke and iron ore. The liquid slag iron passes through the coke material column and drips along the bottom hole of the reactor. At the same time, the reaction gas enters from the gas inlet 13, and then enters the reactor along the corundum support tube 4 and the bottom of the reactor 1 to react with the natural lump ore and coke.

[0087] 3. Simulation reaction and evaluation

[0088] In the first stage, the furnace is heated up and nitrogen is introduced at a flow rate of 1L / min to prevent coke from burning. When the temperature of the material layer reaches 1050℃, the carbon dioxide cylinder is opened for preheating to ensure the stable outflow of carbon dioxide; the temperature is raised to 1100℃, the nitrogen is stopped, and the flow rate of carbon dioxide is changed to 5L / min±0.1L / min, and the temperature is kept at 1100℃ for 2h. In this process, coke and CO2 are gasified (CO2+C—2CO), and the generated CO reacts indirectly with iron ore for reduction (3Fe2O3+CO—2Fe3O4+CO2, Fe3O4+CO—3FeO+CO2, FeO+CO—Fe+CO2), which mainly simulates the reaction of the blast furnace block belt;

[0089] In the second stage, after the first stage, a mixture of 1L / min nitrogen and 0.25Lmin carbon dioxide was introduced, and the temperature continued to rise to 1400℃; in addition to the indirect reduction reaction in the first stage, part of the molten iron ore and coke underwent direct reduction reaction (3Fe2O3+C—2Fe3O4+CO2, Fe3O4+C—FeO+CO2, FeO+C—Fe+CO2), and the molten slag iron minerals and the metallic iron produced by the reduction flowed through the coke column after the reaction and dripped, mainly simulating the blast furnace soft melting dripping zone reaction;

[0090] In the third stage, the temperature was kept constant at 1400℃ for 60min, and 1L / min nitrogen was introduced during the constant temperature process. After the constant temperature was completed, the heating was stopped, and the temperature of the material layer was reduced to below 100℃ by 1L / min nitrogen. The difference between the actual temperature and the furnace temperature to be reached should not exceed 5℃, and the temperature difference between the thermocouple at the center of the furnace top and the bottom of the crucible should not exceed 10℃. The temperature was kept constant under an inert atmosphere, and the fully molten liquid slag iron dripped through the coke material column layer, mainly simulating the reaction of the dead material column in the center of the blast furnace, and finally cooled to room temperature under an inert atmosphere.

[0091] Observe the CO concentration change curve in the exhaust gas ( Figure 4 ) reflects the test process. According to the real-time CO concentration in the tail gas, the CO change curve is recorded and drawn, and it is concluded that the indirect reduction time T1 of iron ore in the simulated reaction process is 210min, the direct reduction time T2 is 18min, and the maximum gasification reaction degree The maximum reduction degree of the molten iron ore is 34.5%. It is 13%.

[0092] The experimental simulation test of the coupling reaction degree between natural lump ore and coke is:

[0093]

[0094] It is to be noted that the above embodiments are only for illustrating the technical concept and features of the present invention, and are not intended to limit the present invention. Any equivalent replacement or modification that does not deviate from the essence of the present invention shall fall within the protection scope of the present invention.

Claims

1. A method for evaluating the coupling reactivity of blast furnace iron ore-coke, comprising raw material pretreatment, charging, simulated reaction and evaluation, characterized in that: According to the real-time CO concentration in the tail gas of the simulated reaction, the CO change curve is recorded and drawn to obtain the indirect reduction and direct reduction time of the iron ore during the simulated reaction, the maximum gasification reactivity and the maximum reduction degree of the molten iron ore dripping through the material column layer; the indirect reduction time of the iron ore refers to the time T1 required for the CO concentration in the tail gas to reach the peak value during the constant temperature process of a certain temperature between 1000 and 1200°C; the direct reduction time refers to the time T2 between the constant temperature point between 1000 and 1200°C and the CO concentration reaching the peak value again during the dripping of the molten slag through the material column layer; the maximum gasification reactivity refers to the peak value of CO concentration in the tail gas during the gasification reaction of coke and CO2, The maximum reduction degree of the molten iron ore dripping through the material column layer refers to the peak value of the tail gas CO concentration during the iron ore dripping process when the temperature is kept constant at a certain temperature between 1000 and 1200°C and then continues to rise.

2. A method for evaluating blast furnace iron ore-coke coupling reactivity according to claim 1, characterized in that: Raw material pretreatment includes coke sample sampling and preparation, iron ore sample sampling and preparation.

3. A method for evaluating blast furnace iron ore-coke coupling reactivity according to claim 2, characterized in that: The iron ore in the raw material pretreatment includes any one of sintered ore, pelletized ore and lump ore.

4. A method for evaluating blast furnace iron ore-coke coupling reactivity according to claim 2, characterized in that: The coke sample sampling and preparation method comprises the following steps: selecting a certain mass of coke and completely discarding foam coke and furnace head coke; crushing and drumming the coke to make approximately spherical particles; sieving to remove coke powder adhering to the coke block, reducing the sample, and placing it in a sealed container for later use.

5. A method for evaluating blast furnace iron ore-coke coupling reactivity according to claim 2 or 3, characterized in that: The iron ore sample sampling and preparation are as follows: for pelletized ore, a test sample with a particle size close to that of coke is obtained by screening, and the test sample is obtained by mixing and shrinking, and the sample is divided into equal parts and placed in a sealed container for later use; for natural lump ore or sintered ore, it is first screened out, and then the large particles are crushed, and then the test sample is screened to obtain a particle size close to that of coke, and the test sample is mixed and shrunk to obtain the test sample, and the sample is divided into equal parts and placed in a sealed container for later use.

6. A method for evaluating blast furnace iron ore-coke coupling reactivity according to claim 1, characterized in that: The charging comprises mixing coke and iron ore or loading them into a high temperature reactor in layers, and then placing the reactor in a high temperature reaction furnace.

7. A method for evaluating blast furnace iron ore-coke coupling reactivity according to claim 6, characterized in that: The reactor is placed in the high-temperature reaction furnace by embedding the reactor in a corundum support tube, the base of the corundum support tube is fixed on the base of the lifting mechanism by bolts, a gas preheating corundum tube is built into the corundum support tube to form a gas preheating interlayer, the corundum tube is a hollow structure, and the reactor slowly enters the high-temperature reaction furnace along with the corundum support tube driven by the lifting mechanism; after the reactor enters the high-temperature reaction furnace, the rising base is clamped, and the bottom of the reactor is sealed under the action of the clamped bolts and the sealing ring; the bottom of the reactor is a porous structure, and the pore size is smaller than the particle size of coke and iron ore.

8. A method for evaluating blast furnace iron ore-coke coupling reactivity according to claim 1, characterized in that: The simulated reaction simulates the continuous iron ore-coke coupling reaction of coke and iron ore through the blast furnace block zone, soft melting dripping zone and central dead material column by controlling the temperature, reaction atmosphere and reaction time. It is specifically divided into three stages: In the first stage, the electric furnace is heated up and nitrogen is introduced to prevent the coke from burning. When the temperature of the material layer reaches 1050℃, the carbon dioxide cylinder is opened for preheating to ensure the stable outflow of carbon dioxide. The temperature is raised to a certain temperature in the range of 1000-1200℃, and the introduction of nitrogen is stopped and replaced with carbon dioxide. The temperature is kept constant for a period of time in the range of 1000-1200℃, and the coke is heated in a N2 atmosphere. Then, CO2 is introduced while the temperature is kept constant. The coke and CO2 are gasified, and the generated CO reacts indirectly with the iron ore to simulate the reaction of the blast furnace block belt. In the second stage, after the first stage, nitrogen and carbon dioxide mixed gas is used, and the temperature is continued to rise to a certain temperature in the range of 1350-1550℃; in addition to the indirect reduction reaction in the first stage, the iron ore partially undergoes a direct reduction reaction with the coke, and the molten slag iron minerals and the metallic iron produced by the reduction flow through the coke column after the reaction and drip, simulating the blast furnace soft melting dripping zone reaction; In the third stage, after the end of the second stage, the highest temperature of the second stage is maintained at a constant temperature for 30 to 60 minutes. Nitrogen is introduced during the constant temperature process. After the constant temperature ends, heating is stopped and the temperature of the nitrogen lower material layer drops to below 100°C. The difference between the actual temperature and the furnace temperature that should be reached should not exceed 5°C, and the temperature difference between the thermocouple at the center of the furnace top and the bottom of the crucible should not exceed 10°C. The fully molten liquid slag drips through the coke column layer to simulate the reaction of the dead column in the center of the blast furnace, and finally cools to room temperature under an inert atmosphere.

9. The method for evaluating the blast furnace iron ore-coke coupling reactivity according to claim 1, characterized in that: The simulated reaction and evaluation refers to the evaluation of the iron ore-coke coupling reactivity value calculated by the CO concentration in the tail gas and the reaction time.

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