Process for the production of direct reduced iron, production system and use

Abstract

The application provides a production method, a production system and application of granular direct reduced iron, and relates to the technical field of smelting. The production method comprises the following steps: contacting granular iron ore with raw material gas in countercurrent at a specific preheating temperature to make the granular iron ore perform a reduction reaction, so as to obtain granular direct reduced iron. Since the particle size of the granular iron ore is small, the reduction reaction speed at the same temperature is faster than that of traditional pellets, and other binders and sintering processes do not need to be introduced, so that the energy consumption and pollution are greatly reduced. Meanwhile, the granular iron ore at a specific preheating temperature is directly subjected to the reduction reaction with the raw material gas, the reduction reaction at low temperature is realized by using the heat of the material itself, the low-temperature reduction reaction does not need special high-temperature-resistant materials, and the sticking probability of the granular direct reduced iron in the reduction process is reduced. By adopting a specific average flow speed of the raw material gas, the raw material gas and the granular iron ore can be more fully contacted, and the utilization efficiency of the raw material gas is greatly improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of smelting, in particular to a production method, a production system and an application of granular direct reduced iron. BACKGROUND

[0002] At present, there are various iron smelting technologies in the global steel smelting industry, including blast furnace iron smelting technology and non-blast furnace iron smelting technology, which is divided into direct reduction and smelting reduction. The direct reduction is divided into gas-based reduction and coal-based reduction. Among them, the blast furnace iron smelting technology has the largest production scale and usage, and a large amount of dust, carbon dioxide and other gases are discharged in the coking and sintering processes in the blast furnace iron smelting process, which brings great pressure to the environment. In the non-blast furnace iron smelting technology, the gas-based reduction process uses reducing gas to reduce the oxidized iron in the iron ore into metallic iron, which is more efficient than the traditional carbon reduction method, does not need coking and sintering, and the production process is cleaner.

[0003] At present, the gas-based reduction technology mainly uses Midrex gas-based shaft furnace technology and HYL gas-based shaft furnace technology. The use of gas-based shaft furnace needs to mix iron ore and binder, high-temperature roasting to obtain oxidized pellets, and then reducing at high temperature using reducing gas. The reducing gas mainly comes from the synthesis gas obtained by steam reforming or reforming of natural gas, the synthesis gas obtained by coal gasification or coke oven tail gas of the coke industry. In the Midrex gas-based shaft furnace, the reducing gas enters the shaft furnace at 850-950℃, and the reaction pressure is about 0.5MPa, which can obtain metallized pellets with a metallization rate of 92-93%; the reducing gas of the HYL gas-based shaft furnace needs to be preheated to 900-960℃, and the reaction pressure is 0.4-0.6MPa, H2 / CO is 5.6-5.9, which can obtain metallized pellets with an average metallization rate of 91-95%.

[0004] In addition to the shaft furnace technology, there is also the fluidized bed technology, among which the most representative are the FINMET technology and the H-IRON technology. The FINMET is a representative technology of the fluidized bed direct reduction, and is currently the only fluidized bed direct reduction process in production, which is jointly developed by Outokumpu and FIORe Company of Venezuela, adopts a four-stage fluidized bed in series, finally obtains a product with a metallization rate of about 93%, and obtains the final product by hot briquetting. The H-IRON technology is a high-pressure low-temperature fluidized reduction technology, which is jointly developed by Hydrocarbon Research Inc and Bethlehom Steel Conp, contains 96% of hydrogen in the reducing gas, adopts a fluidized bed containing three stages of bed, and the ore powder stays in the reduction bed for 45 hours. The operating gas velocity makes the bed operate in the range of the bubbling bed, and the reduction degrees of 47% (first stage), 87% (second stage) and 98% (third stage) are obtained in each stage respectively, the H2 single-pass conversion rate is about 5%, and the operation is intermittent. Due to the economic benefits, there is no commercial device running.

[0005] At present, most of the direct reduction technologies basically adopt the shaft furnace technology, and a small amount of coal-based direct reduction technology is adopted to produce high-metalization-rate metal pellets or hot-pressing pellets into blocks as products. Due to the long residence time of the iron ore powder, the low utilization efficiency of the reducing gas, the low metallization rate of the product, the mutual adhesion of the iron particles at high temperature affecting the fluidization, the unstable operation of the device and the poor economic benefits, only a few plants are still running.

[0006] Therefore, it is necessary and urgent to develop an iron ore gas-based reduction method with low reaction temperature, high utilization rate of reducing gas and without the need of introducing a binder and a sintering process, so as to alleviate the problems of the existing iron ore gas-based shaft furnace reduction technology, such as long iron ore raw material processing flow, high energy consumption and large pollution, and the problems of the gas-based fluidized bed reduction technology, such as low utilization efficiency of reducing gas, low metallization rate of product, long reaction time, high energy consumption and mutual adhesion of iron particles at high temperature affecting the fluidization.

[0007] In view of this, the present application is proposed. SUMMARY

[0008] The first object of the present application is to provide a production method of the pellet direct reduction iron, which does not need to introduce other binders for balling and high-temperature roasting process, greatly reduces pollution and energy consumption, and at the same time, the above-mentioned reduction method adopts a low-temperature reduction method, which not only does not need special high-temperature resistant materials, but also reduces the adhesion probability in the reduction process and reduces the energy consumption.

[0009] The second object of the present application is to provide a production system adopting the production method of the pellet direct reduction iron.

[0010] The third object of the present application is to provide an application of the production method or production system of the pellet direct reduced iron.

[0011] The present application provides a production method of pellet direct reduced iron, comprising the following steps:

[0012] contacting the preheated pellet iron ore and the preheated raw material gas in counter flow, so that the reduction reaction is carried out, and the pellet direct reduced iron is obtained;

[0013] The average particle size of the pellet iron ore is 0.015-4.00mm, the temperature of the preheated pellet iron ore is 500-750℃, the raw material gas contains a reducing gas and an optional dilution gas, the temperature of the preheated raw material gas is 450-650℃, and the average flow rate of the raw material gas is less than the minimum fluidization velocity of the pellet iron ore.

[0014] Further, the reduction reaction pressure is 0.05-3.00MPa;

[0015] Preferably, the flow rate ratio of the reducing gas in the raw material gas to the pellet iron ore is 500-2000Nm 3 reducing gas / t pellet iron ore.

[0016] Further, the reduction reaction time of the pellet iron ore is 1-15h, and more preferably 2-10h.

[0017] Further, the reducing gas contains hydrogen, and the volume fraction of the hydrogen in the reducing gas is not less than 99%;

[0018] Or, the reducing gas contains hydrogen and carbon monoxide, the volume fraction of the hydrogen in the reducing gas is not less than 70%, and the volume fraction of the carbon monoxide in the reducing gas is not more than 10%;

[0019] Preferably, the volume fraction of the reducing gas in the raw material gas is not less than 70%;

[0020] Preferably, the dilution gas includes nitrogen and / or helium.

[0021] Further, the method further comprises the step of performing optional decarburization treatment and dehydration treatment on the reduction tail gas generated in the reduction reaction process, so as to obtain the purified tail gas;

[0022] Preferably, the decarburizer is mixed with the reduction tail gas, so that the decarburization treatment is carried out to remove the carbon dioxide in the reduction tail gas, wherein the decarburizer includes calcium oxide;

[0023] Preferably, the purified tail gas can be reused as the raw material gas;

[0024] Preferably, the calcium carbonate obtained after the decarburization treatment is regenerated at 650-950 DEG C, and the regenerated calcium oxide can be reused as the decarburizer.

[0025] The application also provides a production system of the granular direct reduced iron, which uses the production method of the granular direct reduced iron to produce the direct reduced iron.

[0026] The production system of the granular direct reduced iron comprises a reduction reactor, and the reduction reactor is provided with an air inlet, an air outlet, a feed inlet and a discharge outlet.

[0027] An air inlet pipeline for conveying raw material gas is in communication with the air inlet of the reduction reactor, and the air inlet pipeline is provided with a first preheater.

[0028] Further, the reduction reactor is provided with a rotating component, and the rotating component rotates or moves the particles along a plane perpendicular to the flowing direction of the reduction gas through rotation.

[0029] Further, the reduction reactor comprises one of a through-flow multi-stage furnace reactor, a suspension type rotary kiln reactor and a Longfeng type reactor.

[0030] Further, the production system of the granular direct reduced iron further comprises a condensing device, the air outlet of the reduction reactor is connected with the condensing device, and the condensing device is connected with the air inlet pipeline.

[0031] Alternatively, the production system of the granular direct reduced iron further comprises a decarburization device and a condensing device, the air outlet of the reduction reactor is connected with the decarburization device, the decarburization device is connected with the condensing device, and the condensing device is connected with the air inlet pipeline.

[0032] Preferably, the production system of the granular direct reduced iron further comprises a regeneration device, and the regeneration device is connected with the decarburization device.

[0033] The application also provides application of the production method of the granular direct reduced iron or the production system of the granular direct reduced iron in the field of direct reduced iron production.

[0034] Compared with the prior art, the application has the following beneficial effects:

[0035] (1) The present application provides a production method of pellet direct reduced iron, which contacts the pellet iron ore with specific particle size and specific preheating temperature with raw material gas under specific preheating temperature in countercurrent to make reduction reaction, and obtains pellet direct reduced iron; wherein, due to the small particle size of the pellet iron ore, the reduction reaction speed under the same temperature is faster than that of the traditional pellet, and there is no need to introduce other binders and sintering process, which greatly reduces the energy consumption and pollution, and at the same time, the pellet iron ore under specific preheating temperature is directly reduced with the raw material gas, the reduction reaction under low temperature is realized by using the heat of the material itself, the low temperature reduction reaction not only does not need special high temperature resistant material, but also reduces the bonding probability between solid particles in the reduction process; the average flow rate of the raw material gas is lower than the minimum fluidization velocity of the pellet iron ore, so that the gas will not pass through the bed (pellet iron ore) in the form of bubbles to cause the result of insufficient conversion rate of gas reaction; in addition, compared with the existing iron ore reduction technology, the production method of pellet direct reduced iron provided by the present application has the characteristics of low CO2 and dust emission, and is clean and efficient.

[0036] (2) The present application also provides a production system of pellet direct reduced iron, which uses the above-mentioned production method of pellet direct reduced iron to produce direct reduced iron, and the production system has simple process flow and convenient operation. Due to the advantages of the above-mentioned production method of pellet direct reduced iron, the production system also has the same advantages.

[0037] (3) The present application also provides the application of the above-mentioned production method of pellet direct reduced iron or the production system of pellet direct reduced iron, which has good application in the field of direct reduced iron production due to the advantages of the above-mentioned production method of pellet direct reduced iron or the production system of pellet direct reduced iron. BRIEF DESCRIPTION OF DRAWINGS

[0038] In order to more clearly illustrate the specific embodiments of the present application or the technical solutions in the prior art, the drawings needed in the following specific embodiments or prior art description will be briefly introduced. Obviously, the drawings in the following description are some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0039] Figure 1 The flowchart of the production system of pellet direct reduced iron in one embodiment provided by the present application is shown in the figure;

[0040] Figure 2 The flowchart of the production system of pellet direct reduced iron in another embodiment provided by the present application is shown in the figure;

[0041] Figure 3A flow chart of a production system of the pellet direct reduced iron according to another embodiment of the present application is provided.

[0042] Figure 4 A structure diagram of the through-flow multi-stage furnace reactor according to the present application is provided.

[0043] Figure 5 A structure diagram of the air-suspended rotary kiln reactor according to the present application is provided.

[0044] Figure 6 A structure diagram of the air-suspended rotary kiln reactor according to the present application is provided. Figure 5 A structure diagram of the air-suspended rotary kiln reactor according to the present application is provided.

[0045] Figure 7 A structure diagram of the air-suspended rotary kiln reactor according to the present application is provided.

[0046] Figure 8 A structure diagram of the air-suspended rotary kiln reactor according to the present application is provided. Figure 7 A structure diagram of the air-suspended rotary kiln reactor according to the present application is provided.

[0047] Figure: R1-reduction reactor; E1-first preheater; E2-second preheater; R2-decarbonization device; R3-regeneration device; E3-condensing device;

[0048] 10-housing; 11-stirring shaft; 12-material disc; 13-feeding pipe; 14-stirring arm; 15-scraping plate; 16-air hole;

[0049] 20-main cylinder; 21-variable diameter; 22-rotary cylinder section; 23-closing mechanism; 24-scooping component;

[0050] 30-rotating shaft; 31-spiral blade; 32-air passage; 33-sealing member. DETAILED DESCRIPTION

[0051] The technical solutions of the present application will be described clearly and completely below in conjunction with the embodiments. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all the other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the present application.

[0052] According to a first aspect of the present application, a production method of pellet direct reduced iron is provided, comprising the following steps:

[0053] The preheated pellet iron ore and the preheated raw material gas are contacted in counter flow to make reduction reaction, and pellet direct reduced iron is obtained.

[0054] The average particle size of the particulate iron ore is 0.015-4.00 mm, the temperature of the preheated particulate iron ore is 500-750℃, the raw material gas contains a reducing gas and optionally a dilution gas, the temperature of the preheated raw material gas is 450-650℃, and the average flow rate of the raw material gas is less than the minimum fluidization velocity of the particulate iron ore.

[0055] Specifically, the prior art generally uses oxidized pellets or lump ore as the production raw material of particulate direct reduced iron. When using oxidized pellets as the raw material, the iron ore and the binder need to be mixed and sintered to obtain oxidized pellets, which are then reduced at a high temperature in a reducing gas. This process is time-consuming and labor-intensive, and involves a large amount of energy consumption and the generation of pollutants. More than 80% of iron ore is fine ore, and lump ore is a minority. Crushing to the appropriate particle size also results in a lot of loss, and there are constraints in use. The present application uses particulate iron ore with an average particle size in the specific range of 0.015-4.00 mm as the raw material. Because the particle size of the particulate iron ore is small, the reduction reaction speed at the same temperature is faster than that of traditional oxidized pellets or lump ore, and there is no need to introduce other binders and a sintering process, which can greatly reduce energy consumption and pollution. In addition, particulate iron ore is relatively common on the market, and the raw material is easy to obtain. For example, the particulate iron ore can be derived from any one or a combination of at least two of particulate magnetite, particulate hematite, particulate specularite, oxidized iron scale produced during iron and steel smelting, or smelting slag.

[0056] The average particle size of the particulate iron ore directly affects the speed of the reduction reaction. If the average particle size of the particulate iron ore is too low (less than 0.015 mm), it can easily cause excessive dust and too low a void fraction, which affects the passage of gas, increases the pressure drop and energy consumption. If the average particle size of the particulate iron ore is too high (more than 4.00 mm), it can easily cause a slow reduction rate, a low product metallization rate, and reaction pipeline blockage, etc. Therefore, the average particle size of the particulate iron ore should be limited to a specific range of values. The average particle size of the particulate iron ore is typically, but not limited to, 0.015 mm, 0.02 mm, 0.04 mm, 0.05 mm, 0.08 mm, 0.1 mm, 0.2 mm, 0.4 mm, 0.5 mm, 0.8 mm, 1.0 mm, 1.2 mm, 1.4 mm, 1.5 mm, 1.8 mm, 2.0 mm, 2.2 mm, 2.4 mm, 2.5 mm, 2.8 mm, 3.0 mm, 3.2 mm, 3.4 mm, 3.5 mm, 3.8 mm, or 4.0 mm.

[0057] The raw material gas contains a reducing gas and optionally a dilution gas. The reducing gas is mainly used to reduce the particulate iron ore, and common reducing gases include, but are not limited to, hydrogen, carbon monoxide, and the like. The "optionally" herein means that the raw material gas can only contain the reducing gas, or can contain both the reducing gas and the dilution gas, i.e., the dilution gas can be selectively added. Common dilution gases can be inert gases such as nitrogen, argon, and the like.

[0058] The particulate iron ore and the raw material gas are preheated before the reduction reaction, and the reduction reaction can be carried out at a low temperature by using the heat of the materials themselves. The temperature of the reduction reaction can reach 450-750°C (the temperature of the reduction reaction in the prior art is generally 850-1050°C). The low-temperature reduction reaction not only does not require special high-temperature resistant materials, but also reduces the probability of adhesion between the solid particles in the reduction process. The temperature of the preheated particulate iron ore is 500-750°C, and typical but non-limiting temperatures are 500°C, 550°C, 600°C, 650°C, 700°C, or 750°C. The temperature of the preheated raw material gas is 450-650°C, and typical but non-limiting temperatures are 450°C, 480°C, 500°C, 520°C, 550°C, 580°C, 600°C, 620°C, or 650°C. In addition, the preheating of the particulate iron ore and the raw material gas before the reduction reaction avoids the disadvantage that all the heat is brought in by the preheated gas (shaft furnace), the reaction temperature is more uniform, and the problems of uneven material temperature and adhesion of the material pile are eliminated.

[0059] The preheated particulate iron ore and the preheated raw material gas are countercurrently contacted, which can enhance the gas-solid contact efficiency of the raw material gas and the particulate iron ore, make the reduction reaction more sufficient, and still obtain high conversion rate and metallization rate at a low temperature. The average flow rate of the raw material gas is limited within the minimum fluidization velocity of the particulate iron ore, which ensures the sufficient contact efficiency of the gas when passing through the particulate iron ore, without the need to use a higher gas velocity to ensure the particles in a fluidized state in the fluidized bed, which is generally 0.8-1 m / s. The residence time is short, and the gas passes through the bed in the form of bubbles, so the conversion rate is low, such as the single-pass conversion rate of the gas in H-IRON is only about 5%.

[0060] The minimum fluidization velocity (U mf ) of the particulate iron ore can be measured by experiment or calculated by an empirical formula, and the commonly used empirical formula is (P19, Principles of Fluidization Engineering, Jin Yong, et al.). In the reduction reaction process of the present application, the average flow rate of the raw material gas is less than the minimum fluidization velocity (U mf), the contact between the raw material gas and the particulate iron ore can be more sufficient, the utilization efficiency of the raw material gas can be greatly improved than that of the fluidized bed, and the energy consumption of the process can be reduced. Meanwhile, since the particles do not need to be kept in the fluidized state at all times, the operation flexibility and stability of the production method can be greatly improved.

[0061] The present application provides a production method of particulate direct reduced iron, which comprises the following steps: contacting a particulate iron ore with a raw material gas in countercurrent at a specific preheating temperature to perform a reduction reaction, so as to obtain the particulate direct reduced iron. Since the particle size of the particulate iron ore is small, the reduction reaction speed at the same temperature is faster than that of the traditional pellet, and other binders and sintering processes do not need to be introduced, so that the energy consumption and pollution can be greatly reduced. Meanwhile, the particulate iron ore at a specific preheating temperature is directly contacted with the raw material gas to perform the reduction reaction, and the reduction reaction at low temperature is realized by using the heat of the material itself. The low-temperature reduction reaction not only does not need special high-temperature resistant materials, but also reduces the probability of adhesion between the solid particles in the reduction process. The average flow rate of the raw material gas is lower than the minimum fluidization velocity of the particulate iron ore, so that the gas cannot pass through the bed (particulate iron ore) in the form of bubbles to cause the results of insufficient reaction and low conversion rate. In addition, compared with the existing iron ore reduction technology, the production method of the particulate direct reduced iron provided by the present application has the characteristics of low CO2 and dust emission, and is clean and efficient.

[0062] In a preferred embodiment of the present application, the average particle size of the particulate iron ore is 0.05-2 mm, preferably 0.1-1 mm.

[0063] As a preferred embodiment, the above-mentioned small-particle-size particulate iron ore does not need to introduce other binders and sintering processes, so that the pollution can be greatly reduced. Since the particle size is small, the reduction speed is faster than that of the pellet. Meanwhile, the small-particle-size particles do not need to be fluidized, so that the power consumption of the gas can be greatly reduced.

[0064] As an optional embodiment of the present application, the reduction reaction pressure is 0.05-3.00 MPa. The typical but non-limiting reduction reaction pressures are 0.05 MPa, 0.06 MPa, 0.08 MPa, 0.10 MPa, 0.2 MPa, 0.4 MPa, 0.5 MPa, 0.8 MPa, 1.00 MPa, 1.20 MPa, 1.40 MPa, 1.50 MPa, 1.80 MPa, 2.00 MPa, 2.20 MPa, 2.40 MPa, 2.50 MPa, 2.80 MPa or 3.00 MPa.

[0065] By further limiting the reduction reaction pressure, the flow rate of the reduction gas can be reduced, the pressure drop of the gas passing through the bed can be reduced, and the probability of causing the particles to be fluidized and returned to the mixing state can be reduced.

[0066] As an optional embodiment of the present application, the flow ratio of the reducing gas in the raw gas to the particulate iron ore is 500-2000 Nm 3 The flow ratio of the reducing gas to the particulate iron ore is 500 Nm 3 The flow ratio of the reducing gas to the particulate iron ore is 1000 Nm 3 The flow ratio of the reducing gas to the particulate iron ore is 1500 Nm 3 The flow ratio of the reducing gas to the particulate iron ore is 2000 Nm 3 The flow ratio of the reducing gas to the particulate iron ore is 2000 Nm

[0067] For the flow ratio of the reducing gas in the raw gas to the particulate iron ore, the amount of the reducing gas required is different due to the different types of the particulate iron ore and the distribution of the iron content, and the interval given in the present application is the preferred range for the common iron ore with the total iron content of 50-70%, such as the smelting of the lean iron ore or other iron ore, and the range can be further expanded.

[0068] As an optional embodiment of the present application, the reduction reaction time of the particulate iron ore is 1-15 h. The typical but non-limiting reduction reaction time is 1 h, 2 h, 4 h, 5 h, 6 h, 8 h, 10 h, 12 h, 14 h or 15 h.

[0069] By further limiting the reduction reaction time, the particulate iron ore has sufficient reduction reaction time to obtain high metallization rate, and the efficiency is not low due to the too long reaction time.

[0070] As an optional embodiment of the present application, the reducing gas contains hydrogen, and the volume fraction of hydrogen in the reducing gas is not less than 99%, which can be 99-100%.

[0071] As another optional embodiment of the present application, the reducing gas contains hydrogen and carbon monoxide, the volume fraction of hydrogen in the reducing gas is not less than 90%, and the volume fraction of carbon monoxide in the reducing gas is not more than 10%, i.e. the volume fraction of hydrogen is 90-100%, and the volume fraction of carbon monoxide is 0-10%.

[0072] It should be noted that the carbon monoxide content requirement in the reducing gas is mainly determined according to the source of the reducing gas and the carbon content requirement in the reduced iron. Within the temperature range of the reduction reaction proposed in the present application, carbon monoxide can be decomposed into carbon and carbon dioxide in addition to reducing iron oxides. Therefore, excessive carbon monoxide is prone to disproportionation to generate excessive coke, which can cause the carbon content in the direct reduced iron product to be too high and the metallization rate to decrease. The carbon monoxide content requirement proposed in the present application is given according to the carbon content requirement in the steel smelting industry. The requirement can be adjusted in a larger range according to the needs of downstream smelting without affecting the protection scope of the present application.

[0073] As an optional embodiment of the present application, the volume fraction of the reducing gas in the raw gas is not less than 90%, i.e. the volume fraction of the reducing gas in the raw gas is 90-100%.

[0074] It should be noted that the reducing gas for gas-based reduced iron is generally synthetic gas in the industry, and the volume ratio of H2 / CO is generally 2-6. It is still difficult to use higher hydrogen ratio or even pure hydrogen due to the different proportions of synthetic gas sources, mainly because the reduction of iron oxides by hydrogen is an endothermic reaction, and a too high hydrogen ratio can easily cause the reduction reaction temperature to decrease, resulting in insufficient conversion rate of iron ore powder.

[0075] The production method of the direct reduced iron particles adopted in the present application can obtain high conversion rate and metallization rate at low temperature by using particulate iron ore with specific particle size and enhancing the gas-solid contact efficiency, thereby making it possible to use hydrogen gas with very high hydrogen content or even pure hydrogen as reducing gas and expanding the application range of the composition of the reducing gas. Pure hydrogen (the volume fraction of hydrogen in the reducing gas is not less than 99%) as the reducing gas for reducing particulate iron ore opens up a new smelting route of solar energy→electricity→hydrogen→metallurgy. This process does not emit carbon dioxide, does not need to add artificial binders and sintering, which are necessary in the traditional ironmaking process but are not beneficial to the reduction process and cause environmental pollution, does not use coke, thereby avoiding the emission of carbon dioxide and other gases in the coking process, and reduces energy consumption due to the simple steps.

[0076] As an optional embodiment of the present application, the dilution gas includes nitrogen and / or argon.

[0077] When the raw gas used contains hydrogen, and possibly carbon monoxide and a small amount of carbon dioxide, hydrogen is converted into water vapor and carbon monoxide is converted into carbon dioxide during the reduction process. Due to the existence of chemical equilibrium, the conversion rates of hydrogen and carbon monoxide are basically within 40%. Therefore, the unreacted raw gas in the reducing tail gas needs to be recovered and reused.

[0078] As an optional embodiment of the present application, the method for producing the direct reduced iron pellets further comprises a step of performing optional decarburization treatment and dehydration treatment on the reduction tail gas generated during the reduction reaction to obtain purified tail gas.

[0079] Preferably, the purified tail gas can be reused as the raw gas.

[0080] The decarburization treatment is to remove carbon dioxide in the reduction tail gas. Here, the optional decarburization treatment means that the decarburization treatment can be selectively performed. When the reduction tail gas does not contain carbon dioxide, the decarburization treatment can not be performed, and when the reduction tail gas contains carbon dioxide, the decarburization treatment can be performed. The dehydration treatment is to remove water vapor in the reduction tail gas.

[0081] Since the reduction tail gas has a certain amount of heat, in the industry, the reduction tail gas is generally cooled first and then subjected to decarburization and dehydration, and the decarburization is performed by using pressure swing adsorption or solvent absorption. However, the present application uses a different decarburization method, that is, the reduction tail gas does not need to be cooled and can be directly subjected to the decarburization process.

[0082] As an optional embodiment of the present application, the reduction tail gas does not need to be cooled and is directly mixed with a decarburization agent to remove carbon dioxide in the reduction tail gas, wherein the decarburization agent comprises calcium oxide.

[0083] Since the reduction tail gas has a certain amount of heat, the temperature thereof can reach 400-700°C, and the solid calcium oxide has good absorption capacity for carbon dioxide at this temperature, so the calcium oxide can be used as the decarburization agent. The calcium carbonate obtained after the decarburization treatment is regenerated at 650-950°C, and is changed into calcium oxide and carbon dioxide again. The regenerated calcium oxide can be reused as the decarburization agent. This decarburization method does not need to cool the reduction tail gas, and the heat of the reduction tail gas is more reasonably utilized, especially when the content of carbon dioxide in the reduction tail gas is low.

[0084] In addition, the above decarburization method can also be used to treat raw gas with a high content of carbon dioxide, that is, when the content of carbon dioxide exceeds 3% or the process requires, the preheated raw gas is first subjected to decarburization by using calcium oxide, and then subjected to the reduction reaction with the pelletized iron ore.

[0085] It should be further noted that the reduction reaction of the preheated pelletized iron ore and the preheated raw gas is performed in a reduction reactor, and the reduction reactor needs to realize sufficient contact between the pelletized iron ore and the raw gas to completely avoid material agglomeration or caking.

[0086] As an optional embodiment of the present application, the reduction reactor is provided with a rotating component, wherein the rotating component is a spiral, or a rotating arm, or a rotary drum.

[0087] In order to further realize sufficient contact between the particulate iron ore and the raw material gas, so that the reduction reaction is fully carried out, as a preferred embodiment of the present application, the reduction reactor comprises any one of a through-flow multi-stage furnace reactor, a suspension type rotary kiln reactor or a Longmen type reactor.

[0088] The through-flow multi-stage furnace reactor, the suspension type rotary kiln reactor and the Longmen type reactor are self-developed and designed by the inventors according to actual reaction requirements.

[0089] Specifically, the through-flow multi-stage furnace reactor comprises a shell 10, a stirring shaft 11 and a plurality of material trays 12 arranged at intervals along the axial direction of the shell 10, as shown in Figure 4 The upper part of each material tray 12 is provided with a stirring arm 14, and the stirring arm 14 is connected with a scraper 15 for uniformly distributing the particulate iron ore on the material tray 12. A plurality of air holes 16 are uniformly distributed on each material tray 12 for fully contacting the particulate iron ore uniformly distributed on the material tray 12 with the reducing gas in the raw material gas. The uniform distribution of the raw material gas is realized by the plurality of air holes 16 uniformly distributed on the material tray 12, which can make the raw material gas flow out layer by layer from bottom to top and fully contact with the particulate iron ore uniformly distributed on the material tray 12, effectively increasing the contact area of the particulate iron ore and the reducing gas, and enabling the reaction to be more fully and completely.

[0090] The suspension type rotary kiln reactor comprises a rotary kiln cylinder, as shown in Figure 5 and Figure 6 The rotary kiln cylinder comprises a main cylinder 20 and a variable diameter 21 connected at both ends of the main cylinder and outwardly contracted, and the necked end of the variable diameter 21 is connected with a rotary cylinder segment 22, the rotary cylinder segment 22 is connected with a sealing mechanism 23, and the sealing assembly is arranged at the joint of the rotary cylinder segment and the sealing mechanism. A plurality of lifting assemblies 24 are arranged in the main cylinder 20, which can form a plurality of layers of material curtains when the rotary kiln cylinder rotates, and make the raw material gas pass through the plurality of layers of material curtains and fully contact with the particulate iron ore. By connecting the sealing mechanism 23 on the rotary cylinder segment 22 after necking, the installation difficulty of the sealing assembly between the rotary cylinder segment 22 and the sealing mechanism 23 is reduced, and the plurality of layers of material curtains effectively increase the contact area of the particulate iron ore and the raw material gas, enabling the reaction to be more fully and completely.

[0091] The Longmen type reactor comprises a rotary kiln cylinder, as shown in Figure 7 and Figure 8As shown, the reactor comprises a shell, a rotating shaft 30 is arranged at the center of the shell, a spiral blade 31 for conveying solid materials is connected to the rotating shaft 30, and a plurality of gas passage channels 32 for allowing raw material gas to pass through are arranged on the spiral blade 31; the solid materials fill the reaction cavity of the shell and are in counterflow contact with the raw material gas for reduction reaction. The rotating shaft 30 arranged inside the reactor and the sealing element 33 between the rotating shaft and the shell effectively improve the sealing performance of the reactor and enable the reactor to be operated under pressure. The spiral blade 31 arranged on the rotating shaft 30, in combination with the sealed structure of the reactor, can make the granular iron ore fill the entire reaction cavity space of the reactor, effectively improving the filling rate of the granular iron ore.

[0092] According to a second aspect of the present application, a production system of the granular direct reduced iron is also provided, which uses the above production method of the granular direct reduced iron to produce the granular direct reduced iron.

[0093] The production system of the granular direct reduced iron comprises a reduction reactor R1, and the reduction reactor R1 is provided with a gas inlet, a gas outlet, a material inlet and a material outlet.

[0094] A gas inlet pipeline for conveying raw material gas is in communication with the gas inlet of the reduction reactor, and the gas inlet pipeline is provided with a first preheater E1; a material inlet pipeline for conveying the granular iron ore is in communication with the material inlet of the reduction reactor R1, and the material inlet pipeline is provided with a second preheater E2, and the specific process flow is as shown in Figure 1 .

[0095] Specifically, the first preheater E1 preheats the raw material gas, and the second preheater E2 preheats the granular iron ore; the preheated raw material gas and the preheated granular iron ore enter the reduction reactor R1 through the gas inlet and the material inlet of the reduction reactor R1 respectively and occur counterflow contact for reduction reaction. After the reduction reaction is completed, the reduction tail gas is discharged from the gas outlet of the reduction reactor R1, and the granular direct reduced iron is discharged from the material outlet of the reduction reactor R1.

[0096] As an optional embodiment of the present application, the production system of the granular direct reduced iron further comprises a condensing device, and the gas outlet of the reduction reactor is connected to the condensing device.

[0097] As another optional embodiment of the present application, the production system of the granular direct reduced iron further comprises a decarburization device R2 and a condensing device E3, the gas outlet of the reduction reactor R1 is connected to the decarburization device R2, the decarburization device R2 is connected to the condensing device E3, and the condensing device E3 is connected to the gas inlet pipeline, and the specific structure is as shown in Figure 3 .

[0098] Specifically, after the reduction reaction is completed, the reduction tail gas discharged from the reduction reactor R1 is introduced into the decarburization device R2 to remove the carbon dioxide in the reduction tail gas, and then into the condensing device E3 to remove condensed water. After the carbon dioxide and water are removed from the reduction tail gas, the purified tail gas is obtained. The purified tail gas can be returned to the gas inlet pipeline as raw material gas for reuse, or can be used as purge gas for the next process.

[0099] As another optional embodiment of the present application, the production system of the direct reduced iron particles further comprises a regeneration device R3, and the regeneration device R3 is connected with the decarburization device R2. The specific process flow is shown in Figure 3 .

[0100] The calcium oxide in the decarburization device R2 is changed into calcium carbonate after absorbing the carbon dioxide, and can be sent to the regeneration device R3. The calcium carbonate in the regeneration device R3 is decomposed into carbon dioxide, and the regenerated calcium oxide is re-introduced into the decarburization device R2 for use.

[0101] As another optional embodiment of the present application, the decarburization device R2 can also be used to treat the raw material gas with a high carbon dioxide content. That is, when the carbon dioxide content exceeds 3% or the process requires, the preheated raw material gas is first treated by the decarburization device R2 to remove the carbon dioxide, and then introduced into the reduction reactor R1 to react with the granular iron ore. The calcium oxide in the decarburization device R2 is changed into calcium carbonate after absorbing the carbon dioxide, and can be sent to the regeneration device R3. The calcium carbonate in the regeneration device R3 is decomposed into carbon dioxide, and the regenerated calcium oxide is re-introduced into the decarburization device R2 for use. The specific process flow is shown in Figure 2 .

[0102] As an optional embodiment of the present application, a rotating component is arranged in the reduction reactor.

[0103] As an optional embodiment of the present application, the reduction reactor comprises one of a through-flow type multi-stage furnace reactor, a free-suspension type rotary kiln reactor, or a dragon type reactor.

[0104] The specific types of the rotating component and the reduction reactor have been described above, and will not be repeated here.

[0105] According to a third aspect of the present application, the application of the above-mentioned production method of the direct reduced iron particles or the production system of the direct reduced iron particles in the field of direct reduced iron production is also provided.

[0106] In view of the advantages of the above-mentioned production method of the direct reduced iron particles or the production system of the direct reduced iron particles, the application of the direct reduced iron particles in the field of direct reduced iron production is good.

[0107] The technical solutions of the present application will be further described below in combination with examples and comparative examples.

[0108] Example 1

[0109] The present embodiment provides a method for producing a pellet direct reduced iron, comprising the following steps:

[0110] The preheated pellet iron ore and the preheated raw material gas are countercurrently contacted to make reduction reaction, the reduction reaction pressure is 2.5 MPa, the reduction reaction time of the pellet iron ore is 8 h, and the pellet direct reduced iron is obtained;

[0111] The chemical composition of the pellet iron ore is that the contents of total iron, FeO, SiO2, CaO, MgO, Al2O3 and MnO are 62.7%, 27.3%, 1.32%, 1.53%, 3.45%, 0.82% and 0.28% respectively, the particle size of the pellet iron ore is 100-300 mesh (48-150 μm, and the average particle size is 0.105 mm), and the temperature of the preheated pellet iron ore is 600 ℃.

[0112] The composition of the raw material gas is that the content of H2 is greater than 99.5%, and the temperature of the preheated raw material gas is 600 ℃.

[0113] When the raw material gas flows through the bed, the average flow rate of the gas is 0.065 m / s, and under the conditions of the pellet iron ore with the particle size, the raw material gas and the reaction pressure, the minimum fluidization velocity is 0.086 m / s.

[0114] In the reduction reactor, the flow rate ratio of the reducing gas in the raw material gas to the pellet iron ore is 1400 Nm 3 reducing gas / t pellet iron ore.

[0115] The reduction reactor is a through-flow type multi-stage furnace reactor.

[0116] Example 2

[0117] The present embodiment provides a method for producing a pellet direct reduced iron, comprising the following steps:

[0118] The preheated pellet iron ore and the preheated raw material gas are countercurrently contacted to make reduction reaction, the reduction reaction pressure is 2.5 MPa, the reduction reaction time of the pellet iron ore is 8 h, and the pellet direct reduced iron is obtained;

[0119] The chemical composition of the pellet iron ore is that the contents of total iron, FeO, SiO2, CaO, MgO, Al2O3 and MnO are 62.7%, 27.3%, 1.32%, 1.53%, 3.45%, 0.82% and 0.28% respectively, the particle size of the pellet iron ore is 100-300 mesh (48-150 μm, and the average particle size is 0.105 mm), and the temperature of the preheated pellet iron ore is 600 ℃.

[0120] The raw material gas composition: H2 content is 90%, N2 content is 10%, the temperature of the preheated raw material gas is 550℃.

[0121] When the raw material gas flows through the bed, the average flow rate of the gas is 0.09 m / s, and under the conditions of the particle iron ore of this particle size, the raw material gas, and the reaction pressure, the minimum fluidization velocity is 0.13 m / s.

[0122] In the reduction reactor, the flow ratio of the reducing gas in the raw material gas to the particle iron ore is 1500 Nm 3 Reducing gas / t particle iron ore.

[0123] The reduction reactor is a Jiaolong reactor.

[0124] Example 3

[0125] The present embodiment provides a production method of a particle direct reduced iron, comprising the following steps:

[0126] The preheated particle iron ore and the preheated raw material gas are countercurrently contacted to make the reduction reaction, the reduction reaction pressure is 1.0 MPa, the reduction reaction time of the particle iron ore is 4.5 h, and the particle direct reduced iron is obtained;

[0127] The chemical composition of the particle iron ore is that the contents of total iron, FeO, SiO2, Al2O3, and MnO are 62.67%, 0.59%, 4.52%, 1.59%, and 0.26% respectively, the particle size of the particle iron ore is 40-100 mesh (150-380 μm, and the average particle size is 0.28 mm), and the temperature of the preheated particle iron ore is 650℃.

[0128] The raw material gas composition: H2 content is 75%, CO content is 8%, CO2 content is 0.5%, N2 content is 16.5%, and the temperature of the preheated raw material gas is 600℃.

[0129] When the raw material gas flows through the bed, the average flow rate of the gas is 0.035 m / s, and under the conditions of the particle iron ore of this particle size, the raw material gas, and the reaction pressure, the minimum fluidization velocity is 0.27 m / s.

[0130] In the reduction reactor, the flow ratio of the reducing gas in the raw material gas to the particle iron ore is 1200 Nm 3 Reducing gas / t particle iron ore.

[0131] The reduction reactor is a Jiaolong reactor.

[0132] Example 4

[0133] The present embodiment provides a production method of a particle direct reduced iron, comprising the following steps:

[0134] The preheated granular iron ore and the preheated raw material gas are contacted in countercurrent to make reduction reaction, the reduction reaction pressure is 0.8 MPa, the reduction reaction time of the granular iron ore is 4 h, and the granular direct reduced iron is obtained;

[0135] The chemical composition of the granular iron ore includes total iron, FeO, SiO2, Al2O3, and MnO, and the content of each component is 57.76%, 0.71%, 6.82%, 6.26%, and 1.2% respectively, the particle size of the granular iron ore is 10-40 mesh (380-1700 μm, and the average particle size is 0.78 mm), and the temperature of the preheated granular iron ore is 700°C;

[0136] The raw material gas is composed of H2 with a content of more than 99%, and the temperature of the preheated raw material gas is 570°C.

[0137] When the raw material gas flows through the bed, the average flow rate of the gas is 0.4 m / s, and under the conditions of the iron ore, the raw material gas, and the reaction pressure, the minimum fluidization velocity is 0.63 m / s.

[0138] In the reduction reactor, the flow rate ratio of the reduction gas in the raw material gas to the granular iron ore is 1100 Nm 3 Reduction gas / t granular iron ore.

[0139] The reduction reactor is a hollow suspension rotary kiln reactor.

[0140] Example 5

[0141] The embodiment provides a production method of granular direct reduced iron, which comprises the following steps:

[0142] The preheated granular iron ore and the preheated raw material gas are contacted in countercurrent to make reduction reaction, the reduction reaction pressure is 0.6 MPa, the reduction reaction time of the granular iron ore is 5 h, and the granular direct reduced iron is obtained;

[0143] The chemical composition of the granular iron ore includes total iron, FeO, SiO2, CaO, MgO, Al2O3, and MnO, and the content of each component is 55.2%, 0.29%, 8.69%, 0.01%, 0.01%, 6.53%, and 0.07% respectively, the particle size of the granular iron ore is 5-40 mesh (380-4000 μm, and the average particle size is 1.05 mm), and the temperature of the preheated granular iron ore is 750°C;

[0144] The raw material gas is composed of H2 with a content of 88%, CO with a content of 0.5%, CO2 with a content of 0.3%, CH4 with a content of 2.5%, and N2 with a content of 8.7%, and the temperature of the preheated raw material gas is 500°C.

[0145] The average flow rate of the gas through the bed was 0.5 m / s, while the minimum fluidization velocity was 0.82 m / s under the conditions of the particulate iron ore, the raw material gas, and the reaction pressure of the particle size.

[0146] The flow rate ratio of the reducing gas in the raw material gas to the particulate iron ore in the reduction reactor was 950 Nm 3 Reducing gas / particulate iron ore.

[0147] The reduction reactor was an empty suspension rotary kiln reactor.

[0148] Example 6

[0149] This embodiment provides a production system of particulate direct reduced iron, which can use the production method of particulate direct reduced iron in Examples 1-5 to produce particulate direct reduced iron.

[0150] The production system of particulate direct reduced iron includes a reduction reactor R1, and the reduction reactor R1 is provided with a gas inlet, a gas outlet, a material inlet, and a material outlet;

[0151] A gas inlet pipeline for conveying the raw material gas is in communication with the gas inlet of the reduction reactor, and the gas inlet pipeline is provided with a first preheater E1; a material inlet pipeline for conveying the particulate iron ore is in communication with the material inlet of the reduction reactor R1, and the material inlet pipeline is provided with a second preheater E2, and a specific process flow diagram is shown as Figure 1 .

[0152] The specific reaction process is that the first preheater preheats the raw material gas, and the second preheater preheats the particulate iron ore; the preheated raw material gas and the preheated particulate iron ore enter the reduction reactor through the gas inlet and the material inlet of the reduction reactor respectively, and occur countercurrent contact to perform a reduction reaction. After the reduction reaction is completed, the reduction tail gas is discharged from the gas outlet of the reduction reactor, and the particulate direct reduced iron is discharged from the material outlet of the reduction reactor.

[0153] Example 7

[0154] This embodiment provides a production system of particulate direct reduced iron, which can use the production method of particulate direct reduced iron in Examples 3 and 5 to produce particulate direct reduced iron.

[0155] The production system of particulate direct reduced iron includes a reduction reactor R1, and the reduction reactor R1 is provided with a gas inlet, a gas outlet, a material inlet, and a material outlet;

[0156] The gas inlet pipeline for conveying raw material gas is communicated with the gas inlet of the reduction reactor R1, and the first preheater E1 is arranged on the gas inlet pipeline. The feed inlet pipeline for conveying the particulate iron ore is communicated with the feed inlet of the reduction reactor R1, and the second preheater E2 is arranged on the feed inlet pipeline.

[0157] The particulate direct reduced iron production system further comprises a decarburization device R2, a condensation device E3 and a regeneration device R3. The exhaust port of the reduction reactor R1 is connected with the decarburization device R2. The decarburization device R2 is connected with the condensation device E3. The condensation device E3 is connected with the gas inlet pipeline. The regeneration device R3 is connected with the decarburization device R2. The specific arrangement is shown in Figure 3

[0158] The specific reaction process is as follows. The first preheater preheats the raw material gas. The second preheater preheats the particulate iron ore. The preheated raw material gas and the preheated particulate iron ore enter the reduction reactor through the gas inlet and the feed inlet of the reduction reactor respectively, and perform a countercurrent contact to perform a reduction reaction. After the reduction reaction is completed, the reduction tail gas is discharged from the exhaust port of the reduction reactor, and the particulate direct reduced iron is discharged from the discharge port of the reduction reactor.

[0159] The reduction tail gas discharged from the reduction reactor R1 is introduced into the decarburization device R2 to remove carbon dioxide in the reduction tail gas. Subsequently, the reduction tail gas enters the condensation device E3 to remove condensed water. After the carbon dioxide and the water are removed from the reduction tail gas, the purified tail gas is obtained. The purified tail gas can be partially or entirely returned to the gas inlet pipeline as the raw material gas for recycling, or can be partially or entirely used as the purge gas for entering the next process. The calcium oxide in the decarburization device R2 is converted into calcium carbonate after absorbing the carbon dioxide. The calcium carbonate can be sent to the regeneration device R3. The calcium carbonate in the regeneration device R3 is decomposed into carbon dioxide and discharged. The regenerated calcium oxide reenters the decarburization device R2 for use.

[0160] Comparative Example 1

[0161] This comparative example provides a production method of particulate direct reduced iron. Except that the average particle size of the particulate iron ore is 500-2000 mesh (corresponding to a particle size of 6.5-25 μm, and an average particle size of 12 μm), the remaining raw material composition, process parameters and production steps are the same as those of Example 1. Under the conditions of the particulate iron ore, the raw material gas and the reaction pressure at this particle size, the minimum fluidization velocity is 0.026 m / s.

[0162] Comparative Example 2

[0163] This comparative example provides a production method of particulate direct reduced iron. Except that the particle size of the particulate iron ore is 4-12 mm (an average particle size of 7.6 mm), the remaining raw material composition, process parameters and production steps are the same as those of Example 3.

[0164] Comparative Example 3 ​

[0165] The present comparative example provides a production method of the pellet direct reduced iron, except that the preheating temperature of the pellet iron ore is 480°C, the preheating temperature of the raw material gas is 440°C, and the rest of the raw material composition, process parameters and production steps are the same as those of Example 4.

[0166] In order to compare the technical effects of each example and comparative example, the following experimental examples are provided.

[0167] Experimental Example 1

[0168] The metallization rate, carbon content, reduction gas conversion rate and total iron content of the pellet direct reduced iron in each example and comparative example are detected, and the specific results are shown in Table 1.

[0169] Table 1

[0170] Experimental group Metalization rate Carbon content Reduction gas conversion rate Total iron content Example 1 98.8％ - 23.6％ 89.0％ Example 2 98.7％ - 26.0％ 93.4％ Example 3 96.8％ 2.6％ 30.3％ 86.4％ Example 4 97.8％ - 30.7％ 79.6％ Example 5 96.7％ 0.2％ 33.7％ 77.2％ Comparative Example 1 50.3％ - 12.0％ 75.1％ Comparative Example 2 82.7％ 0.7％ 26.2％ 84.2％ Comparative Example 3 9.7％ - 3.0％ 61.2％

[0171] Note: "-" represents that the carbon content is 0.

[0172] As can be seen from the data in Table 1, by using the production method of the pellet direct reduced iron of the present application, the utilization efficiency of the reduction gas is greatly improved while obtaining a high metallization rate, and the conversion rate reaches 23-34%, which is much higher than the conversion rate of 5% of the fluidized bed, which means that the energy consumption is greatly reduced. By using the iron ore powder with high iron content, the total iron content of the product reaches 93%, which is the highest grade of reduced iron.

[0173] Comparative Example 1 uses pellet iron ore with too small size, so the minimum fluidization velocity is small, the average flow velocity of the raw material gas is higher than the minimum fluidization velocity, and the bed (pellet iron ore) is in a fluidized state, which causes gas short circuiting, and the product can only obtain a metallization rate of 50%, and the reduction gas conversion rate is also greatly reduced.

[0174] Comparative Example 2 uses pellet iron ore with too large size, and due to the increase in size, under the same reaction conditions and time, the conversion rate of the pellet iron ore decreases, the product metallization rate decreases, and the reduction gas utilization rate decreases.

[0175] In Comparative Example 3, both the pellet iron ore and the raw material gas use a lower preheating temperature, so that the reduction reaction temperature is lower, and as a result, the conversion rates of the pellet iron ore and the reduction gas are sharply reduced. From the perspective of kinetics and reaction rules, it is easy to conclude that the reaction rate increases with the increase of temperature, but too high a reaction temperature will require higher material requirements, and the heat loss will increase the energy consumption, and under the preferred reaction temperature of the present application, a high conversion rate and a high metallization rate can be achieved below 750°C.

[0176] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, and are not intended to limit the present application; although the present application has been described in detail with reference to the above embodiments, those skilled in the art should understand that the technical solutions recorded in the above embodiments can be modified, or some or all of the technical features can be replaced by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for producing granular direct reduced iron, characterized in that, Includes the following steps: Preheated granular iron ore and preheated raw material gas are brought into countercurrent contact to carry out a reduction reaction. The reduction reaction pressure is 2.5 MPa and the reduction reaction time of the granular iron ore is 8 hours to obtain granular direct reduced iron. The average particle size of the granular iron ore is 48-150 μm, and the temperature of the preheated granular iron ore is 600℃. The temperature of the preheated raw material gas is 600℃; When the feed gas flows through the bed, the average gas velocity is 0.065 m / s, while under the conditions of granular iron ore of this size, feed gas and reaction pressure, the minimum fluidization velocity is 0.086 m / s. The raw material gas contains reducing gas and optional diluting gas; In the reduction reactor, the flow ratio of reducing gas to particulate iron ore is 1400 Nm³. 3 Reducing gas / t iron ore; The reduction reactor is a through-flow multi-stage furnace reactor, which includes: a shell, a stirring shaft, and multiple material trays spaced apart along the axial direction of the shell. The material trays are connected to a discharge pipe for feeding material. Each material tray is equipped with a stirring arm at the top, and a scraper is connected to the stirring arm for uniformly distributing the granular iron ore on the material tray. Each material tray has multiple air holes evenly distributed on it.

2. A method for producing granular direct reduced iron, characterized in that, Includes the following steps: Preheated granular iron ore and preheated raw material gas are brought into countercurrent contact to carry out a reduction reaction. The reduction reaction pressure is 1.2 MPa and the reduction reaction time of the granular iron ore is 3 hours to obtain granular direct reduced iron. The average particle size of the granular iron ore is 75-270 μm, and the temperature of the preheated granular iron ore is 650℃. The temperature of the preheated raw gas is 550℃; When the feed gas flows through the bed, the average gas velocity is 0.09 m / s, while under the conditions of granular iron ore of this size, feed gas and reaction pressure, the minimum fluidization velocity is 0.13 m / s. The raw material gas contains reducing gas and optional diluting gas; In the reduction reactor, the flow ratio of the reducing gas to the granular iron ore is 1500 Nm3 reducing gas / t iron ore. The reduction reactor is a auger reactor, which includes a shell, a rotating shaft mounted on the axis of the shell, and spiral blades for conveying solid materials connected to the rotating shaft. The spiral blades are provided with multiple gas passages for the raw material gas to pass through, and a seal is installed between the rotating shaft and the shell.

3. A method for producing granular direct reduced iron, characterized in that, Includes the following steps: Preheated granular iron ore and preheated raw material gas are brought into countercurrent contact to carry out a reduction reaction. The reduction reaction pressure is 1.0 MPa and the reduction reaction time of the granular iron ore is 4.5 h to obtain granular direct reduced iron. The average particle size of the granular iron ore is 150-380 μm, and the temperature of the preheated granular iron ore is 650℃. The temperature of the preheated raw material gas is 600℃; When the feed gas flows through the bed, the average gas velocity is 0.035 m / s, while under the conditions of granular iron ore of this size, feed gas and reaction pressure, the minimum fluidization velocity is 0.27 m / s. The raw material gas contains reducing gas and optional diluting gas; In the reduction reactor, the flow ratio of reducing gas to particulate iron ore is 1200 Nm³. 3 Reducing gas / t iron ore; The reduction reactor is a auger reactor, which includes a shell, a rotating shaft mounted on the axis of the shell, and spiral blades for conveying solid materials connected to the rotating shaft. The spiral blades are provided with multiple gas passages for the raw material gas to pass through, and a seal is installed between the rotating shaft and the shell.

4. The method for producing particulate direct reduced iron according to any one of claims 1-3, characterized in that, The reducing gas contains hydrogen, and the volume fraction of hydrogen in the reducing gas is not less than 99%.

5. The method for producing particulate direct reduced iron according to any one of claims 1-3, characterized in that, The reducing gas contains hydrogen and carbon monoxide, wherein the volume fraction of hydrogen in the reducing gas is not less than 90%, and the volume fraction of carbon monoxide in the reducing gas is not greater than 10%.

6. The method for producing particulate direct reduced iron according to any one of claims 1-3, characterized in that, The volume fraction of the reducing gas in the raw material gas is not less than 70%.

7. The method for producing particulate direct reduced iron according to any one of claims 1-3, characterized in that, It also includes the step of optionally decarbonizing and dehydrating the reduction tail gas generated during the reduction reaction to obtain purified tail gas.

8. The method for producing particulate direct reduced iron according to claim 7, characterized in that, The purified exhaust gas can be reused as raw material gas.

9. The method for producing particulate direct reduced iron according to claim 8, characterized in that, A decarbonizing agent is mixed with reducing tail gas to perform decarbonization treatment to remove carbon dioxide from the reducing tail gas, wherein the decarbonizing agent includes calcium oxide.

10. The method for producing particulate direct reduced iron according to claim 9, characterized in that, The calcium carbonate obtained after decarbonization is regenerated at 650-950℃, and the regenerated calcium oxide can be reused as a decarbonization agent.

11. A production system for granular direct reduced iron, characterized in that, The method for producing particulate direct reduced iron according to any one of claims 1-10 is used to produce particulate direct reduced iron. The production system for granular direct reduced iron includes a reduction reactor, which is equipped with an air inlet, an exhaust outlet, a feed inlet, and a discharge outlet. An inlet pipe for conveying raw material gas is connected to the inlet of the reduction reactor, and a first preheater is provided on the inlet pipe. A feed pipe for conveying granular iron ore is connected to the feed inlet of the reduction reactor, and a second preheater is provided on the feed pipe.

12. The production system for particulate direct reduced iron according to claim 11, characterized in that, It also includes a condensation device, the exhaust port of the reduction reactor is connected to the condensation device, and the condensation device is connected to the air inlet pipe.

13. The particle direct reduced iron production system according to claim 12, the particle direct reduced iron production system further includes a decarburization device and a condensation device, the exhaust port of the reduction reactor is connected to the decarburization device, the decarburization device is connected to the condensation device, and the condensation device is connected to the air inlet pipe.

14. The production system for particulate direct reduced iron according to claim 13, wherein the production system for particulate direct reduced iron further includes a regeneration device, the regeneration device being connected to the decarburization device.

15. The application of the production method of granular direct reduced iron according to any one of claims 1-10 or the production system of granular direct reduced iron according to any one of claims 11-14 in the field of direct reduced iron production.

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