Metallurgy method for producing molten iron for steelmaking by reducing and smelting iron ore through hydrogen

Abstract

The invention relates to the technical field of metallurgy, and discloses a metallurgical method for producing molten iron steelmaking by reducing and smelting iron ore through hydrogen, which comprises the following steps: mixing iron ore powder with a slag former, a binder and water according to a certain proportion, and pelletizing the mixture to obtain green pellets; the manufactured green pellets are sintered; the sintered pellets are added into an electric furnace and heated to 1500 DEG C or above to be melted to form a molten pool, hydrogen is blown into the molten pool for smelting, and molten iron and furnace slag are generated through a reaction; and when the molten iron in the electric furnace reaches a certain amount, feeding is stopped, after the reaction is finished, hydrogen blowing is stopped, part of slag is discharged, pellets and slag formers are added into the furnace, the components of the slag are adjusted, and oxygen is blown into the furnace for steelmaking. The hydrogen reduction electric smelting process is adopted, hydrogen serves as a reducing agent, iron ore powder is reduced in an electric furnace to directly obtain molten iron, hydrogen and electricity are efficiently cooperated, then molten iron is used for steelmaking, coal coke is not needed, and the method is clean, environmentally friendly and low in energy consumption.

Description

Technical Field

[0001] The invention belongs to the technical field of metallurgy, and in particular relates to a metallurgical method for producing molten iron and steelmaking by reducing and smelting iron ore with hydrogen. Background Art

[0002] Metallurgical production emits a large amount of CO2. Hydrogen metallurgy is an important direction for low-carbon development in the current metallurgical field. Currently, the methods of hydrogen metallurgy include: 1. Hydrogen direct reduction of iron This technology uses H2 or H2-CO mixed gas to replace CO or C to reduce iron oxides into sponge iron at a temperature below the melting point of iron. The specific methods are: (1) Gas-based vertical furnace method Iron oxide pellets are added from the top of the shaft furnace, and hydrogen-rich hot reducing gas is introduced from the center. The charge and the hot air move in opposite directions, reducing the iron oxides to sponge iron. Heat is provided by coal or electricity, keeping the temperature below 1200°C.

[0003] (2) Gas-based fluidized bed method The preheated iron ore powder is fed into the fluidized bed by a screw feeder, and hydrogen is fed into the fluidized bed to react with the iron ore powder. Microwave heating is used at a temperature below 1200°C, and the product is iron powder.

[0004] (3) Gas-based rotary kiln method Iron ore powder and coal are added to a rotary kiln. The coal is burned to provide heat, and the temperature is controlled at 1050°C to 1150°C. Hydrogen is introduced into the rotary kiln to reduce the iron oxides. The product is iron powder.

[0005] 2. Hydrogen blast furnace ironmaking This technology is based on the existing blast furnace ironmaking technology, blowing hydrogen into the blast furnace to reduce CO2 emissions. However, the heating energy still relies on coke.

[0006] 3. Hydrogen molten reduction ironmaking This technology builds on existing smelting reduction methods by replacing coal with hydrogen or hydrogen-rich gas as the reducing agent. Iron is first melted in an induction furnace to form a molten iron pool. Iron ore fines, a slag-forming agent, and hydrogen are then sprayed into the molten iron pool for smelting reduction. Alternatively, hydrogen is used in a rotary kiln or fluidized bed to reduce the iron ore fines to iron powder. The iron powder and slag-forming agent are then sprayed into the molten iron pool for smelting. These methods cannot completely eliminate coal and are not pure hydrogen metallurgy. They also consume high energy and have high production costs. Summary of the Invention

[0007] The purpose of the present invention is to address the above problems and provide a metallurgical method for producing molten iron and steelmaking by smelting iron ore using hydrogen reduction, a hydrogen reduction electric smelting process, which allows hydrogen and electricity to work together efficiently, extract iron and make steel, does not require coal coke, and is clean.

[0008] To achieve the above object, the present invention adopts the following technical solution: A metallurgical method for producing molten iron and steelmaking by reducing and smelting iron ore with hydrogen, comprising the following steps: (1) Mixing iron ore powder, slag-making agent and binder in a certain proportion, adding water to obtain a mixture, the water content of the mixture is 10%, and pelletizing the mixture to obtain green pellets; (2) Dry the green pellets at 200-300°C, then heat them to 700-800°C for sintering, so that the moisture content of the sintered pellets is less than 1%; (3) Add the sintered pellets to the electric furnace. If 20mm~30mm lump ore is used, add it directly to the electric furnace and heat it to above 1500℃ to form a molten pool. Blow reducing gas hydrogen into the molten pool for smelting. Add materials continuously during the hydrogen smelting process to react and generate molten iron and slag. The generated molten iron sinks to the bottom of the electric furnace. During the hydrogen reduction process, the following chemical reactions occur: 3Fe2O3+H2=2Fe3O4+3H2O Fe3O4+H2=3FeO+H2O FeO + H2 = 3Fe + H2O (4) When the amount of molten iron in the electric furnace reaches a certain level, stop adding material. After the reaction is completed, stop blowing hydrogen and release some slag. (5) Add sintered pellets and slag-making agent to the electric furnace, adjust the slag-iron mass ratio to 1:10, the FeO mass content in the slag to 30%, and the slag basicity (CaO / SiO2) between 2 and 3. Heat the molten iron to above 1600°C, blow oxygen into the furnace to remove impurities in the molten iron, and obtain molten steel; (6) When the molten steel reaches the tapping requirements, stop heating and blowing oxygen, pour out the slag first, and then tap the steel.

[0009] Preferably, the slag-forming agent is CaO, AlO3, and SiO2, and the amount of the slag-forming agent added in step (1) is the amount required to make the slag-iron ratio formed after the iron ore powder is reduced to 0.3-0.6 and the slag basicity (CaO / SiO2) to be 1.2-1.5.

[0010] Preferably, the amount of the binder added is 0.8% to 1% of the total mass of the iron ore powder and the slag-forming agent.

[0011] Preferably, the binder is bentonite.

[0012] Preferably, the diameter of the green pellets is controlled to be 20 mm to 30 mm during the pelletizing process.

[0013] Preferably, the amount of hydrogen introduced is 100% more than the amount required to completely reduce the iron oxides and the like in the ore.

[0014] Preferably, the slag from step (4) and step (6) is used to prepare light calcium carbonate and mullite after water quenching.

[0015] The preparation method of light calcium carbonate is similar to the preparation method of mullite: the slag is water-quenched and placed in a decalcification reactor, water and CO2 are introduced into the decalcification reactor, and the Ca(OH)2 in the water-quenched slag reacts with CO2 to form water-soluble calcium bicarbonate. The chemical reaction is: Ca(OH)2+2CO2=Ca(HCO3)2 After filtration, solid slag containing Al2O3 and SiO2 and Ca(HCO3)2 aqueous solution are obtained. The aqueous solution is heated to above 60℃, and calcium bicarbonate decomposes to form calcium carbonate, which is filtered to obtain light calcium carbonate. Due to the adoption of the above technical solution, the present invention has the following beneficial effects: The present invention adopts a hydrogen reduction electric smelting process, using hydrogen as a reducing agent to reduce iron ore powder in an electric furnace to directly obtain molten iron, making hydrogen and electricity work together efficiently. The molten iron is then used to make steel without the use of coal coke, which is clean, green and low in energy consumption. DETAILED DESCRIPTION

[0016] The specific implementation of the present invention is further described below with reference to the examples. Example 1

[0017] A metallurgical method for producing molten iron and steelmaking by reducing and smelting iron ore using hydrogen comprises the following steps: (1) Iron ore powder, slag-forming agents CaO, Al2O3, SiO2, and binder bentonite are mixed in a certain proportion. The mass composition of the iron ore powder and slag-forming agent is: Fe2O3 70%, CaO 15%, SiO2 10%, Al2O3 5%. Then water is added to obtain a mixture. The water content of the mixture is 10%. The mixture is pelletized to obtain green pellets. The diameter of the green pellets is 20mm to 30mm. The particle size of the iron ore powder is 80μm. The amount of bentonite added is 1% of the total mass of the iron ore powder and slag-forming agent. (2) Dry the green pellets at 200°C for 3 hours and sinter at 700°C for 3 hours. The moisture content of the sintered pellets is less than 1%. (3) The sintered pellets are added to an AC electric arc furnace and heated to 1550°C to melt and form a molten pool. Hydrogen is blown into the molten pool for smelting. During the hydrogen smelting process, materials are continuously added to react to generate molten iron and slag. The generated molten iron sinks to the bottom of the electric furnace, and the generated slag floats on the top of the molten iron. The amount of hydrogen introduced is 100% in excess of the amount required to completely reduce the iron oxides in the molten pool. The flue gas discharged from the electric furnace enters the combustion chamber, and air is introduced into the combustion chamber. The remaining hydrogen in the flue gas burns in the air. The heat released and the heat of the flue gas discharged from the electric furnace are used to generate electricity, and the water vapor is recycled and utilized. The dust is recovered and returned to (1) for pelletizing.

[0018] The chemical reaction is 2H2+O2=2H2O.

[0019] (4) When the molten iron and slag in the electric arc furnace reach a certain amount, stop adding materials. After the reaction is completed, stop blowing hydrogen and release part of the slag; (5) Continue to add sintered pellets and slag-making agent into the electric arc furnace to make the slag-iron mass ratio reach 1:10, the FeO mass content in the slag reach 30%, and the slag basicity (CaO / SiO2) is maintained at 2.6. Heat the molten iron to increase the temperature to 1650℃, blow oxygen into the furnace to remove impurities in the molten iron; (6) When the temperature required for steel tapping is reached, stop heating, stop blowing oxygen, add carbon appropriately, pour out the slag first, and then tap the steel.

[0020] The slag released in steps (4) and (6) is quenched with water and used to prepare light calcium carbonate and mullite. The preparation method of light calcium carbonate and mullite is as follows: the slag is quenched with water and placed in a decalcification reactor, water and CO2 are introduced into the decalcification reactor, and Ca(OH)2 in the quenched slag reacts with CO2 to generate water-soluble calcium bicarbonate. The chemical reaction is: Ca(OH)2+2CO2=Ca(HCO3)2 After filtration, solid slag containing Al2O3 and SiO2 and Ca(HCO3)2 aqueous solution are obtained. The aqueous solution is heated to above 60℃, and calcium bicarbonate decomposes to form calcium carbonate, which is filtered to obtain light calcium carbonate. The chemical reaction is: Ca(HCO3)2=CaCO3+H2O+CO2 The preparation method of mullite is as follows: adjusting the decalcified solid slag containing Al2O3 and SiO2 to a molar ratio of 3:2, heating it in an AC arc furnace to above 1800°C to melt it, and casting it into an ingot to obtain fused mullite; The iron recovery rate of the method is over 97%, the calcium oxide recovery rate in the slag is over 95%, the aluminum oxide recovery rate in the slag is over 92%, and the silicon dioxide recovery rate is over 90%. Example 2

[0021] A metallurgical method for producing molten iron and steelmaking by reducing and smelting iron ore using hydrogen comprises the following steps: (1) Iron ore powder, slag-forming agents CaO, Al2O3, SiO2, and binder bentonite are mixed in a certain proportion. The mass composition of the iron ore powder and slag-forming agent is: Fe2O3 80%, CaO 10%, SiO2 7%, Al2O3 3%. Water is then added to obtain a mixture with a water content of 10%. The mixture is pelletized to obtain green pellets with a diameter of 20 mm to 30 mm. The particle size of the iron ore powder is 60 μm to 80 μm. The amount of bentonite added is 0.8% of the total mass of the iron ore powder and slag-forming agent. (2) The green pellets are dried at 250°C for 2 hours and sintered at 800°C for 2.5 hours, so that the moisture content of the sintered pellets is less than 1%; (3) The sintered pellets are added to an AC electric arc furnace and heated to 1600°C to melt and form a molten pool. Hydrogen is blown into the molten pool for smelting. During the hydrogen smelting process, materials are continuously added to react to generate molten iron and slag. The generated molten iron sinks to the bottom of the electric furnace, and the generated slag floats on the top of the molten iron. The amount of hydrogen introduced is 100% excess to completely reduce the iron oxides in the molten pool. The flue gas generated during the reaction enters the combustion chamber, and air is introduced into the combustion chamber. The remaining hydrogen in the flue gas burns in the air. The heat generated by the combustion and the heat of the flue gas are used to generate electricity. The remaining heat is then used to recover water vapor. The chemical reaction that occurs is 2H2+O2=2H2O. The water vapor is recovered and the dust is recovered and returned to (1) pelletizing. (4) When the slag and molten iron in the AC arc furnace reach a certain amount, stop adding materials. After the reaction is completed, stop blowing hydrogen and release part of the slag; (5) Add sintered pellets and slag-making agent to the AC arc furnace, adjust the slag-iron mass ratio to 1:10, the FeO mass content in the slag to 30%, maintain the slag basicity (CaO / SiO2) at 3, heat the molten iron to 1650℃, blow oxygen into the furnace to remove impurities in the molten iron; (6) When the temperature required for steel tapping is reached, stop heating, stop blowing oxygen, increase carbon appropriately, meet the requirements of molten steel, pour out the slag first, and then tap the steel.

[0022] The generated slag is used to prepare light calcium carbonate and mullite after water quenching; the preparation method of light calcium carbonate and the preparation method of mullite are the same as those in Example 1.

[0023] The iron recovery rate of the method is over 97%, the recovery rate of calcium oxide separated by slag decalcification is over 95%, the recovery rate of aluminum oxide in the slag is over 92%, and the recovery rate of silicon dioxide is over 90%. Example 3

[0024] (1) Add 20mm~30mm iron ore lumps and slag-making agent into the electric arc furnace, heat to 1600℃ to melt and form a molten pool, blow hydrogen into the molten pool for smelting, and continuously add materials during the hydrogen smelting process to react and generate molten iron and slag, which sinks to the bottom of the electric furnace; the amount of hydrogen introduced is 100% excess to completely reduce the iron oxides in the molten pool; (2) The flue gas generated during the reaction enters the combustion chamber, and air is introduced into the combustion chamber. The remaining hydrogen in the flue gas burns in the air. The heat generated by the combustion and the heat of the flue gas are used to generate electricity. The remaining heat is used to recover water vapor. The chemical reaction that occurs is 2H2+O2=2H2O. The water vapor is recovered and the dust is recovered and returned to (1) for pelletizing. (3) When the slag and molten iron in the electric arc furnace reach a certain amount, stop adding materials. After the reaction is completed, stop blowing hydrogen and release part of the slag; (4) Add sintered pellets and slag-making agent to the electric arc furnace, adjust the slag-iron mass ratio to 1:10, the FeO mass content in the slag to 30%, maintain the slag basicity (CaO / SiO2) at 2.6, heat the molten iron to 1650℃, blow oxygen into the furnace to remove impurities in the molten iron; (5) When the temperature required for steel tapping is reached, stop heating, stop blowing oxygen, increase carbon appropriately, meet the requirements of molten steel, pour out the slag first, and then tap the steel.

[0025] (6) The slag produced is quenched with water to prepare light calcium carbonate and mullite in the same manner as in Example 1.

[0026] The iron recovery rate of the method is over 97%, the recovery rate of calcium oxide separated by slag decalcification is 95%, the recovery rate of aluminum oxide in the slag is over 92%, and the recovery rate of silicon dioxide is over 90%.

[0027] The present invention adopts a hydrogen reduction electric smelting process, using hydrogen as a reducing agent to reduce iron ore powder in an electric furnace to directly obtain molten iron, so that hydrogen and electricity work together efficiently, and then the molten iron is used to make steel without the use of coal coke. It is clean, green and has low energy consumption.

[0028] The above description is a detailed description of the preferred embodiments of the present invention, but the embodiments are not intended to limit the scope of the patent application of the present invention. All equivalent changes or modifications made under the guidance of the present invention should be covered by the patent of the present invention.

Claims

1. A metallurgical method for producing molten iron and steelmaking by reducing and smelting iron ore using hydrogen, characterized in that: The following steps are involved: (1) Mix iron ore powder with slag-making agent, binder and water in a certain proportion, with the water content of the mixture being 10%, and pelletize the mixture to obtain green pellets; (2) Dry the green pellets at 200-300°C, then heat them to 700-800°C for sintering, so that the moisture content of the sintered pellets is less than 1%; (3) The sintered pellets are added to an electric furnace and heated to above 1500°C to melt and form a molten pool. Hydrogen is blown into the molten pool for smelting. During the hydrogen smelting process, materials are continuously added to react and generate molten iron and slag. The generated molten iron sinks to the bottom of the electric furnace. (4) When the amount of molten iron in the electric furnace reaches a certain level, stop adding materials. After the reaction is completed, stop blowing hydrogen and release some slag. (5) Add sintered pellets and slag-making agent into the electric furnace to make the slag-iron mass ratio reach 1:10, the FeO mass content in the slag reach 30%, and the slag basicity (CaO / SiO2) is between 2 and 3. Heat the molten iron to raise the temperature to above 1600℃, blow oxygen into the furnace to remove impurities in the molten iron, and obtain molten steel; (6) When the molten steel reaches the tapping requirements, stop heating and blowing oxygen, pour out the slag first, and then tap the steel.

2. The metallurgical method for producing molten iron and steel by reducing and smelting iron ore using hydrogen according to claim 1, characterized in that: The slag-forming agent is CaO, AlO3, and SiO2. The amount of the slag-forming agent added in step (1) is the amount required to make the slag-iron ratio formed after the iron ore powder is reduced to 0.3-0.6 and the slag basicity (CaO / SiO2) to be 1.2-1.

5.

3. The metallurgical method for producing molten iron and steel by reducing and smelting iron ore using hydrogen according to claim 1, characterized in that: The amount of the binder added is 0.8% to 1% of the total mass of the iron ore powder and the slag-forming agent.

4. The metallurgical method for producing molten iron and steel by reducing and smelting iron ore using hydrogen according to claim 3, characterized in that: The binder is bentonite.

5. The metallurgical method for producing molten iron and steel by reducing and smelting iron ore using hydrogen according to claim 1, characterized in that: In the pelletizing process, the diameter of the green pellets is controlled to be 20 mm to 30 mm.

6. The metallurgical method for producing molten iron and steel by reducing and smelting iron ore using hydrogen according to claim 1, characterized in that: The amount of hydrogen introduced is 100% in excess of the amount required to completely reduce the iron oxides and the like in the ore.

7. The metallurgical method for producing molten iron and steel by reducing and smelting iron ore using hydrogen according to claim 1, characterized in that: The slag in step (4) is used to prepare light calcium carbonate and mullite after water quenching.