Storage and transportation method for direct reduction iron product of gas-based shaft furnace

Abstract

The invention relates to a storage and transportation method for a gas-based shaft furnace direct reduction iron product, and belongs to the technical field of metallurgical methods. According to the technical scheme, qualified products discharged by the gas-based shaft furnace enter a belt conveyor to be conveyed, and all belt vestibules of the whole conveying path are closed; materials are screened through a vibrating screen classifier in the belt conveying process; the unloading trolley feeds materials into a silo for inerting storage, the temperature, the oxygen content and the hydrogen content in the silo are monitored in real time, and nitrogen is injected through an upper nitrogen pipeline, a middle nitrogen pipeline and a lower nitrogen pipeline of the silo for cooling inerting operation; a stone ladder is arranged in the silo to prevent the materials from being damaged after falling from a high place; and wet dust removal is adopted. The transportation system has the beneficial effects that the quality and safety of the whole transportation process of the direct reduction iron product are ensured by adopting the means of closed belt vestibule transportation, inerting storage, dedusting ash collection and treatment and the like, and meanwhile, the environmental protection requirement is met.

Description

Technical Field

[0001] The invention relates to a storage and transportation method for a gas-based shaft furnace direct-reduced iron product, belonging to the technical field of metallurgical methods. Background Art

[0002] In the development of modern metallurgy, it is of vital importance to attach importance to the effective application of DRI (Direct Reduced Iron), a product of gas-based shaft furnace smelting. The application of DRI is not only an effective means to solve environmental problems, but also a high-quality raw material for electric furnace and blast furnace production. In the process of continuous development of the metallurgical industry in the future, we should give full play to the positive role of DRI in modern metallurgy and promote the green, stable, efficient and sustainable development of my country's modern metallurgical industry. Since my country's DRI production achieved a zero breakthrough in 1994, it has developed rapidly in recent years. DRI may be ignited due to chemical reactions when exposed to oxygen and water, generating heat and flammable gas-hydrogen, thereby forming an explosive environment. In any case, DRI must be properly transported and stored to prevent large-scale secondary oxidation and avoid reaching its melting point due to uncontrolled temperature rise of DRI. Since the cold finished material-DRI is easily oxidized when exposed to air, both from the design perspective and from the operation perspective, appropriate safety measures must be considered in the transportation and storage systems of DRI (such as conveyors and silos in the product material conveying system). To this end, it is necessary to rationally design and configure the DRI storage system to meet the factory's production quality requirements for products and ensure that the equipment and storage methods comply with national environmental protection requirements. Summary of the invention

[0003] The object of the present invention is to provide a method for storing and transporting gas-based vertical furnace direct reduced iron products. By adopting closed belt corridor transportation, inerting storage, dust collection and treatment, etc., the quality and safety of the entire transportation process of direct reduced iron products are guaranteed, while meeting environmental protection requirements, and effectively solving the above-mentioned problems existing in the background technology.

[0004] The technical solution of the present invention is: a method for storing and transporting gas-based shaft furnace direct reduced iron products, comprising the following steps: S1. Belt transportation: qualified products discharged from the gas-based vertical furnace enter the belt conveyor for transportation, and each belt corridor of the entire transportation route is closed; S2. Material screening: During the belt transportation, the material is screened by a vibrating screener. After screening, there are large particles of material on the screen and small particles of material under the screen. The material on the screen continues to be transported by the belt, and the material under the screen enters the powder bin for storage and is then put into a transport vehicle or a transport belt conveyor for transport to other further processing procedures. S3, silo inerting storage, unloading trolleys load materials into the silo for inerting storage, real-time monitoring of temperature, oxygen content and hydrogen content in the silo, nitrogen is injected through the three nitrogen pipelines at the top, middle and bottom of the silo for cooling and inerting operation; stone stairs are set in the silo to prevent materials from falling and being damaged; S4. Dust collection and treatment. Wet dust removal is used. The belt corridor suction point sucks the DRI material dust into the wet dust collector for the first water mist dust removal, and then sucks it into the wet electrostatic precipitator for secondary electrostatic adsorption of the DRI material dust.

[0005] In step S1, each belt corridor is equipped with a fire extinguisher and the fire source is controlled, explosion-proof equipment is used for electrical appliances, and spilled materials and accumulations are cleaned up in a timely manner.

[0006] In the step S3, immediately after the material is fed into the silo, the nitrogen pipeline in the middle of the silo is started to fill the middle of the silo with nitrogen until the oxygen content detector in the silo top shows 3%, and then the nitrogen filling is stopped; during the period, the silo is continuously filled, and the nitrogen filling is started when the oxygen content in the silo top is 4%, and it is stopped when it drops to 3%, and the low oxygen environment in the silo is continuously maintained by reciprocating; when the DRI material in the silo is abnormal, the hydrogen content in the silo will increase significantly, and when the hydrogen content in the silo is greater than 900PPM, the upper nitrogen pipeline in the silo is opened for nitrogen filling, and when the hydrogen content is less than 300PPM, it is stopped; in special cases, the DRI material in the silo will have a tendency to self-ignite and the temperature in the silo will rise rapidly when it is abnormal. When the temperature in the silo is detected to be greater than 60°, the upper, middle and lower nitrogen pipelines are all opened to continue nitrogen filling until the temperature returns to normal.

[0007] In step S3, the unloading trolley moves above the silo. When it is necessary to unload into the silo, the trolley moves to the top of the silo, aligns with the top of the silo, seals all around, and the material falls into the silo for inerting.

[0008] In step S3, a radar level meter is also provided in the silo, which is located at the top of the silo, continuously measures the DRI height, has a detection height range of 0 to 35 m, sets two levels of height forecast, and issues corresponding sound and light alarms.

[0009] In step S4, the DRI material dust reaches the environmental protection standard of less than 10 mg and is discharged into the atmosphere, wherein the sludge water containing DRI dust after atomization and electrostatic adsorption is pumped into the sedimentation tank through the sludge water pump, and the sludge water is precipitated in the sedimentation tank, and the upper clear liquid directly overflows into the clear liquid tank and is sucked away by the power system water suction pump for recycling as industrial water; the sediment at the bottom of the sedimentation tank is grabbed by the overhead crane grab bucket to the sludge tank for draining, and then the valuable materials are grabbed and recovered for further processing and use as needed.

[0010] The beneficial effects of the present invention are as follows: by adopting means such as closed belt corridor transportation, inerting storage, dust collection and treatment, the quality and safety of the entire transportation process of direct reduced iron products are guaranteed, while meeting environmental protection requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 It is a structural schematic diagram of the belt conveyor system of the present invention; Figure 2 It is a schematic diagram of the structure of the silo system of the present invention; Figure 3 It is a schematic diagram of the structure of the dust removal system of the present invention; In the figure: D1 belt conveyor 1, material sampling device 2, quantitative feeder 3, buffer bin 4, D2 belt conveyor 5, 1# vibrating screen 6, 2# vibrating screen 7, S1 belt conveyor 8, D3 belt conveyor 9, powder ore bin 10, D4 belt conveyor 11, D5 belt conveyor 12, unloading trolley 13, silo 14, radar level meter 15, oxygen content monitor 16, infrared temperature monitor 17, Stone stairs 18, hydrogen content monitor 19, thermocouple temperature monitor 20, nitrogen pressure tank 21, nitrogen flow meter 22, pneumatic knife gate valve 23, gravity flap valve 24, three-way distributor 25, telescopic chute 26, belt conveyor for next process 27, wet dust collector 28, wet electrostatic precipitator 29, sedimentation tank 30, clear liquid tank 31, sludge tank 32, overhead crane grab bucket 33, belt corridor dust suction point 34, gas-based vertical furnace 35. DETAILED DESCRIPTION

[0012] In order to make the purpose, technical solutions and advantages of the invention implementation cases clearer, the technical solutions in the implementation cases of the present invention will be clearly and completely described below in conjunction with the drawings in the implementation cases. Obviously, the implementation cases described are only a small part of the implementation cases of the present invention, rather than all the implementation cases. Based on the implementation cases in the present invention, all other implementation cases obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0013] A method for storing and transporting a gas-based shaft furnace direct reduced iron product comprises the following steps: S1. Belt transportation: qualified products discharged from the gas-based vertical furnace enter the belt conveyor for transportation, and each belt corridor of the entire transportation route is closed; S2. Material screening: During the belt transportation, the material is screened by a vibrating screener. After screening, there are large particles of material on the screen and small particles of material under the screen. The material on the screen continues to be transported by the belt, and the material under the screen enters the powder bin for storage and is then put into a transport vehicle or a transport belt conveyor for transport to other further processing procedures. S3, silo inerting storage, unloading trolleys load materials into the silo for inerting storage, real-time monitoring of temperature, oxygen content and hydrogen content in the silo, nitrogen is injected through the three nitrogen pipelines at the top, middle and bottom of the silo for cooling and inerting operation; stone stairs are set in the silo to prevent materials from falling and being damaged; S4. Dust collection and treatment. Wet dust removal is used. The belt corridor suction point sucks the DRI material dust into the wet dust collector for the first water mist dust removal, and then sucks it into the wet electrostatic precipitator for secondary electrostatic adsorption of the DRI material dust.

[0014] In step S1, each belt corridor is equipped with a fire extinguisher and the fire source is controlled, explosion-proof equipment is used for electrical appliances, and spilled materials and accumulations are cleaned up in time.

[0015] In the step S3, immediately after the material is fed into the silo, the nitrogen pipeline in the middle of the silo is started to fill the middle of the silo with nitrogen until the oxygen content detector in the silo top shows 3%, and then the nitrogen filling is stopped; during the period, the silo is continuously filled, and the nitrogen filling is started when the oxygen content in the silo top is 4%, and it is stopped when it drops to 3%, and the low oxygen environment in the silo is continuously maintained by reciprocating; when the DRI material in the silo is abnormal, the hydrogen content in the silo will increase significantly, and when the hydrogen content in the silo is greater than 900PPM, the upper nitrogen pipeline in the silo is opened for nitrogen filling, and when the hydrogen content is less than 300PPM, it is stopped; in special cases, the DRI material in the silo will have a tendency to self-ignite and the temperature in the silo will rise rapidly when it is abnormal. When the temperature in the silo is detected to be greater than 60°, the upper, middle and lower nitrogen pipelines are all opened to continue nitrogen filling until the temperature returns to normal.

[0016] In step S3, the unloading trolley moves above the silo. When it is necessary to unload into the silo, the trolley moves to the top of the silo, aligns with the top of the silo, seals all around, and the material falls into the silo for inerting.

[0017] In step S3, a radar level meter is also provided in the silo, which is located at the top of the silo, continuously measures the DRI height, has a detection height range of 0 to 35 m, sets two levels of height forecast, and issues corresponding sound and light alarms.

[0018] In step S4, the DRI material dust reaches the environmental protection standard of less than 10 mg and is discharged into the atmosphere, wherein the sludge water containing DRI dust after atomization and electrostatic adsorption is pumped into the sedimentation tank through the sludge water pump, and the sludge water is precipitated in the sedimentation tank, and the upper clear liquid directly overflows into the clear liquid tank and is sucked away by the power system water suction pump for recycling as industrial water; the sediment at the bottom of the sedimentation tank is grabbed by the overhead crane grab bucket to the sludge tank for draining, and then the valuable materials are grabbed and recovered for further processing and use as needed.

[0019] In practical applications, the present invention includes a D1 belt conveyor 1, a material sampling device 2, a quantitative feeder 3, a buffer bin 4, a D2 belt conveyor 5, a 1# vibrating screen 6, a 2# vibrating screen 7, an S1 belt conveyor 8, a D3 belt conveyor 9, a powder ore bin 10, a D4 belt conveyor 11, a D5 belt conveyor 12 and a discharge trolley 13. After being discharged from the vertical furnace, the DRI product falls into the D1 belt 1, from which the material sampling device 2 can take samples to inspect the quality of DRI; then it passes through the buffer bin 3. When the gas-based vertical furnace needs to discharge some unqualified products during the heating process, the quantitative feeder measures the excess amount and can be directly stored in the buffer bin through the three-way powder feeder or directly transported out of the transportation system. When the qualified products are discharged, the quantitative feeder measures the excess amount and then enters the buffer bin and directly enters the D2 belt conveyor 5 through the three-way distributor; after entering the D2 conveyor, it is transported to the 1# vibration screening machine 6 or the 2# vibration screening machine 7; after screening, there are large particles and small particles under the screen. The material, the screened material is discharged into the D3 belt conveyor for further belt transportation, the screened material enters the S1 belt conveyor 8 and then enters the powder bin for storage, and can be put into the reverse transport vehicle or reverse transport belt conveyor for reverse transportation to other further processing procedures; the screened material is discharged into the D3 belt conveyor for further belt transportation to the D4 belt conveyor 11 and then further transported to the D5 belt conveyor 12; the D5 belt conveyor 12 transports the material to the unloading trolley 13; the unloading trolley 13 can move above the silo. When it is necessary to unload into the silo, after the unloading trolley 13 moves to the top of the silo, the unloading trolley is aligned with the top of the silo and sealed on all sides, and the material can fall into the silo 14 for inerting.

[0020] like Figure 1 , three silos are set up for alternating DRI inerting.

[0021] Figure 2 As shown in the figure, the silo system, after the DRI product enters the silo, it falls to the stone steps 18 to prevent the material from being damaged after falling from a high place; the inside of the silo is set from top to bottom with two radar level meters 15, one oxygen content monitor 16, two infrared temperature monitors 17, one hydrogen content monitor 19, and sixteen thermocouple temperature monitors 20, which start real-time monitoring in sequence. When the temperature, gas and other measured parameters in the gas monitoring equipment exceed the limit alarm, the nitrogen gate valve is opened, and nitrogen is injected through the three nitrogen pipelines at the top, middle and bottom of the silo to cool down and inertate, dilute the concentration of flammable and explosive gases in the silo, and suppress the spontaneous combustion and smoldering of the deoxygenated pellets. The radar level meter 15 is located at the top of the silo, and the two radar level monitors are used to monitor the real-time material level, which can continuously measure the DRI height, detect the height of 0 to 35m, set a two-level height forecast, and issue a corresponding sound and light alarm. The nitrogen pressure tank 21 and the nitrogen flow meter 22 are used for real-time monitoring to ensure the delivery stability of the nitrogen system.

[0022] After inerting for 72 hours, an oxide film is formed on the surface of the metal structure, and the pneumatic knife gate valve 23 and the gravity flap valve 24 can be opened in sequence to perform material transfer operations. When the vehicle needs to unload the material, the three-way distributor 25 opens to the telescopic chute 26, and the material is discharged dust-free to the unloading vehicle for transportation to the next processing step. Since the finished DRI material can be directly added to the electric furnace for steelmaking, the material can be discharged through the three-way distributor 25 to the next process belt conveyor 27, and directly transported to the fixed electric furnace for further smelting and processing.

[0023] The oxygen content monitor 16 is used to detect the oxygen concentration. It is not affected by strong magnetic interference and is not afraid of moisture. It can work normally under low temperature (-38℃). It has a built-in alarm and can alarm at the scene and the control room at the same time.

[0024] In the dust removal system, at multiple belt corridor dust suction points, DRI material dust is sucked into the wet dust collector 28 through the pipeline for the first water mist dust removal, and then sucked into the wet electrostatic precipitator 29 for secondary electrostatic adsorption of DRI dust, and discharged into the atmosphere after reaching the environmental protection standard of <10mg. The sludge water containing DRI dust after atomization and electrostatic adsorption is pumped into the sedimentation tank 30 through the sludge water pump. This part of the sludge water is precipitated in the sedimentation tank 30, and the upper part of the clear liquid directly overflows into the clear liquid tank 31 and is sucked away by the power system water pump as industrial water for recycling. The sediment at the bottom of the sedimentation tank 30 is grabbed by the overhead crane grab 33 and taken to the sludge tank 32 for draining, and then the valuable materials are grabbed and recovered for further processing and use as needed.

Claims

1. A method for storing and transporting gas-based shaft furnace direct reduced iron products, characterized in that The following steps are involved: S1. Belt transportation: qualified products discharged from the gas-based vertical furnace enter the belt conveyor for transportation, and each belt corridor of the entire transportation route is closed; S2. Material screening: During the belt transportation, the material is screened by a vibrating screener. After screening, there are large particles of material on the screen and small particles of material under the screen. The material on the screen continues to be transported by the belt, and the material under the screen enters the powder bin for storage and is then put into a transport vehicle or a transport belt conveyor for transport to other further processing procedures. S3, silo inerting storage, unloading trolleys load materials into the silo for inerting storage, real-time monitoring of temperature, oxygen content and hydrogen content in the silo, nitrogen is injected through the three nitrogen pipelines at the top, middle and bottom of the silo for cooling and inerting operation; stone stairs are set in the silo to prevent materials from falling and being damaged; S4. Dust collection and treatment. Wet dust removal is used. The belt corridor suction point sucks the DRI material dust into the wet dust collector for the first water mist dust removal, and then sucks it into the wet electrostatic precipitator for secondary electrostatic adsorption of the DRI material dust.

2. The method for storing and transporting gas-based shaft furnace direct reduced iron products according to claim 1, characterized in that: In step S1, each belt corridor is equipped with a fire extinguisher and the fire source is controlled, explosion-proof equipment is used for electrical appliances, and spilled materials and accumulations are cleaned up in a timely manner.

3. The method for storing and transporting gas-based shaft furnace direct reduced iron products according to claim 1, characterized in that: In the step S3, immediately after the material is fed into the silo, the nitrogen pipeline in the middle of the silo is started to fill the middle of the silo with nitrogen until the oxygen content detector in the silo top shows 3%, and then the nitrogen filling is stopped; during the period, the silo is continuously filled, and the nitrogen filling is started when the oxygen content in the silo top is 4%, and it is stopped when it drops to 3%, and the low oxygen environment in the silo is continuously maintained by reciprocating; when the DRI material in the silo is abnormal, the hydrogen content in the silo will increase significantly, and when the hydrogen content in the silo is greater than 900PPM, the upper nitrogen pipeline in the silo is opened for nitrogen filling, and when the hydrogen content is less than 300PPM, it is stopped; in special cases, the DRI material in the silo will have a tendency to self-ignite and the temperature in the silo will rise rapidly when it is abnormal. When the temperature in the silo is detected to be greater than 60°, the upper, middle and lower nitrogen pipelines are all opened to continue nitrogen filling until the temperature returns to normal.

4. The method for storing and transporting gas-based shaft furnace direct reduced iron products according to claim 1, characterized in that: In step S3, the unloading trolley moves above the silo. When it is necessary to unload into the silo, the trolley moves to the top of the silo, aligns with the top of the silo, seals all around, and the material falls into the silo for inerting.

5. The method for storing and transporting gas-based shaft furnace direct reduced iron products according to claim 1, characterized in that: In step S3, a radar level meter is also provided in the silo, which is located at the top of the silo, continuously measures the DRI height, has a detection height range of 0 to 35 m, sets two levels of height forecast, and issues corresponding sound and light alarms.

6. The method for storing and transporting gas-based shaft furnace direct reduced iron products according to claim 1, characterized in that: In step S4, the DRI material dust reaches the environmental protection standard of less than 10 mg and is discharged into the atmosphere, wherein the sludge water containing DRI dust after atomization and electrostatic adsorption is pumped into the sedimentation tank through the sludge water pump, and the sludge water is precipitated in the sedimentation tank, and the upper clear liquid directly overflows into the clear liquid tank and is sucked away by the power system water suction pump for recycling as industrial water; the sediment at the bottom of the sedimentation tank is grabbed by the overhead crane grab bucket to the sludge tank for draining, and then the valuable materials are grabbed and recovered for further processing and use as needed.

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