An electric arc furnace small pool, multi-pool smelting process method

Abstract

The present application relates to a kind of electric arc furnace small pool, multi-pool smelting process method, belong to metallurgical industry electric arc furnace smelting technical field.The technical scheme is: after electric arc furnace tapping, in the remaining slag surface sequentially add lime, light-burned dolomite and scrap steel;After electric arc furnace hole-through power-on begins, add carbon-containing auxiliary material to the vicinity of three-phase electrode, and utilize oxygen lance to spray oxygen;After electrode hole-through ends, form multiple small pools in the vicinity of three-phase electrode at the bottom of electric arc furnace;Scrap steel is constantly melted, multiple small pools constantly expand and gather, and form initial large pool;Batch lime 10-20kg / t and light-burned dolomite 10-20kg / t are added to the pool, and constantly form foam slag by acting with overflow gas in the pool, and finally foam slag covers the entire pool.The beneficial effects of the present application are: suitable for electric arc furnace high proportion scrap steel or full scrap steel smelting, can reduce heat loss of arc radiation to cover, improve heat transfer efficiency, reduce smelting power consumption, shorten smelting cycle.

Description

Technical Field

[0001] This invention relates to a smelting process for small and multiple molten pools in an electric arc furnace, belonging to the field of electric arc furnace smelting technology in the metallurgical industry. Background Technology

[0002] In the steel industry, CO2 emissions mainly originate from the coke / coal-based blast furnace-converter process, primarily concentrated in the blast furnace's iron production process. Adopting electric arc furnace (EAF) smelting can effectively reduce CO2 emissions. When using all-scrap steel in an EAF, CO2 emissions are approximately one-third of those in the blast furnace-converter process. However, EAF smelting with all-scrap steel is time-consuming and energy-intensive. In the EAF steelmaking process, forming suitable foamed slag in the molten pool early on can shorten smelting time and reduce energy consumption. The foamed slag increases the slag-steel contact interface, accelerating oxygen transfer and the physicochemical reactions between slag and steel. Simultaneously, the submerged arc effect of a certain thickness of foamed slag reduces heat loss radiated from the electric arc to the furnace cover and walls during the melting period. This increases the furnace lifespan of the furnace cover and walls, improves heat transfer efficiency, reduces smelting power consumption, accelerates the heating rate of molten steel, shortens the smelting cycle, increases production efficiency, and reduces costs.

[0003] The invention patent "A process for making foamy slag in the molten pool of an electric arc furnace" (authorization announcement number CN 104131134 B) discloses a process for making foamy slag in an electric arc furnace. The method uses a hot-charged molten iron ratio of 30-75% and makes foamy slag by blowing graphite-like materials. The disadvantage of this method is that a large amount of hot-charged molten iron needs to be added and a flat molten pool needs to be formed in the electric arc furnace before foamy slag can be made. It is not suitable for electric arc furnaces to use high proportions of scrap steel or all scrap steel for smelting. Summary of the Invention

[0004] The purpose of this invention is to provide a smelting process for small or multiple molten pools in an electric arc furnace, which is suitable for smelting high-proportion or all-scrap steel in an electric arc furnace. It can reduce heat loss radiated from the electric arc to the furnace cover and furnace wall, improve heat transfer efficiency, reduce smelting power consumption, shorten the smelting cycle, and solve the problems existing in the background technology.

[0005] The technical solution of this invention is:

[0006] A smelting process for small-pool and multi-pool electric arc furnaces is operated according to the following steps:

[0007] ①After tapping steel from the electric arc furnace, add 200-500 kg of lime, 50-200 kg of lightly calcined dolomite and scrap steel to the remaining slag surface in sequence;

[0008] ② After the electric arc furnace is powered on through the well, add carbon-containing auxiliary materials near the three-phase electrodes and use an oxygen lance to blow oxygen.

[0009] ③ After the electrode penetration is completed, multiple small molten pools are formed near the three-phase electrodes at the bottom of the electric arc furnace. At the same time, the added carbon-containing auxiliary materials fall onto the slag surface of the small molten pools, and the CO and CO2 gases generated by the chemical reaction escape. The carbon-containing auxiliary materials and slag react on the small molten pools to form foamy slag. As the power continues to be supplied, the electrodes heat the scrap steel and continuously melt it. The multiple small molten pools near the three-phase electrodes continue to expand and converge, forming an initial large molten pool near the three-phase electrodes. During this stage, foamy slag is continuously formed, and the coverage area of ​​the foamy slag continues to expand as the molten pools grow.

[0010] ④ Continue to power on the scrap steel until it is clear. After the initial large molten pool is formed for 5-10 minutes, add 10-20 kg / t of lime and 10-20 kg / t of lightly calcined dolomite to the molten pool in batches. During this process, the added slag continuously melts and reacts with the gas overflowing from the molten pool to continuously form foam slag. Finally, the foam slag covers the entire molten pool.

[0011] In step ④, lime and lightly calcined dolomite are added to the molten pool in three separate additions, with an interval of 3-8 minutes between each addition.

[0012] In step ②, the carbon-containing auxiliary material added near the three-phase electrodes is added continuously before the scrap steel is melted and cleaned, and the addition amount is 50-100 kg / min.

[0013] In step ②, the carbon-containing auxiliary material added near the three-phase electrodes has a particle size of 3-30mm, a carbon content of not less than 50%, and a moisture content of not more than 0.5%.

[0014] In step ②, the oxygen injection rate is 60-120 Nm. 3 / min.

[0015] In step ②, carbon-containing auxiliary materials are added near the three-phase electrodes through the feeding port on the furnace cover of the electric arc furnace.

[0016] The beneficial effects of this invention are as follows: This smelting process is suitable for electric arc furnaces using a high proportion of scrap steel or all scrap steel. From the formation of multiple small molten pools near the three-phase electrodes after drilling, foamed slag is created throughout the process. By using foamed slag to submerge the arc, heat loss radiated from the electric arc to the furnace cover and walls is reduced. This increases the lifespan of the electric arc furnace cover and walls while improving heat transfer efficiency, reducing smelting power consumption, accelerating the heating rate of molten steel, and shortening the average smelting cycle per furnace by 3-5 minutes, thereby improving production efficiency and reducing costs. Attached Figure Description

[0017] Figure 1 A schematic diagram of an electric arc furnace before heating after adding scrap steel and turning on the power.

[0018] Figure 2 A schematic diagram showing the formation of multiple small molten pools on the outer side of the three-phase electrodes after the electric arc furnace is powered on and penetrates the well.

[0019] Figure 3 A schematic diagram showing how multiple small molten pools outside the three-phase electrodes grow and converge into an initial large molten pool after the electric arc furnace passes through the well and continues to be heated by electricity;

[0020] In the diagram: 1. Three-phase electrode; 2. Scrap steel; 3. Furnace shell; 4. Eccentric furnace bottom tap hole; 5. Furnace bottom tilting device; 6. Furnace cover; 7. Slag; 8. Molten steel; 9. Tilting mechanical device; 10. Feed port; 11. Small molten pool; 12. Initial large molten pool. Implementation

[0021] The invention will be further described below with reference to the accompanying drawings and examples.

[0022] See attached document Figure 1-3 A smelting process for small-pool and multi-pool electric arc furnaces is operated according to the following steps:

[0023] ①After tapping steel from the electric arc furnace, add 200-500 kg of lime, 50-200 kg of lightly calcined dolomite and scrap steel to the remaining slag surface in sequence;

[0024] ② After the electric arc furnace is powered on through the well, add carbon-containing auxiliary materials near the three-phase electrodes and use an oxygen lance to blow oxygen.

[0025] ③ After the electrode penetration is completed, multiple small molten pools are formed near the three-phase electrodes at the bottom of the electric arc furnace. At the same time, the added carbon-containing auxiliary materials fall onto the slag surface of the small molten pools, and the CO and CO2 gases generated by the chemical reaction escape. The carbon-containing auxiliary materials and slag react on the small molten pools to form foamy slag. As the power continues to be supplied, the electrodes heat the scrap steel and continuously melt it. The multiple small molten pools near the three-phase electrodes continue to expand and converge, forming an initial large molten pool near the three-phase electrodes. During this stage, foamy slag is continuously formed, and the coverage area of ​​the foamy slag continues to expand as the molten pools grow.

[0026] ④ Continue to power on the scrap steel until it is clear. After the initial large molten pool is formed for 5-10 minutes, add 10-20 kg / t of lime and 10-20 kg / t of lightly calcined dolomite to the molten pool in batches. During this process, the added slag continuously melts and reacts with the gas overflowing from the molten pool to continuously form foam slag. Finally, the foam slag covers the entire molten pool.

[0027] In step ④, lime and lightly calcined dolomite are added to the molten pool in three separate additions, with an interval of 3-8 minutes between each addition.

[0028] In step ②, the carbon-containing auxiliary material added near the three-phase electrodes is added continuously before the scrap steel is melted and cleaned, and the addition amount is 50-100 kg / min.

[0029] In step ②, the carbon-containing auxiliary material added near the three-phase electrodes has a particle size of 3-30mm, a carbon content of not less than 50%, and a moisture content of not more than 0.5%.

[0030] In step ②, the oxygen injection rate is 60-120 Nm. 3 / min.

[0031] In step ②, carbon-containing auxiliary materials are added near the three-phase electrodes through the feeding port on the furnace cover of the electric arc furnace.

[0032] In this embodiment, the appendix Figure 1 A schematic diagram of the electric arc furnace before heating after adding scrap steel. After the electric arc furnace taps steel through the eccentric bottom tap 4, 200-500 kg of lime and 50-200 kg of lightly calcined dolomite are added. Then scrap steel 2 is added. To ensure the quality of the molten steel in the ladle, a small amount of molten steel 8 and slag 9 are left in the electric arc furnace.

[0033] Appendix Figure 2 This diagram illustrates the formation of multiple small molten pools on the outer side of the three-phase electrodes after the electric arc furnace is powered on and penetrates the well. During the process of the electric arc furnace being powered on and penetrating the well, the scrap steel near the three-phase electrode 1 is heated and melted. The three-phase electrode 1 moves downward to complete the well penetration process, and multiple small molten pools 11 are formed near the three-phase electrode 1. During this process, carbon-containing auxiliary materials are added to the vicinity of the three-phase electrodes through the charging port 10 on the furnace cover 6, and oxygen is injected using an oxygen lance. After the well penetration process is completed, the carbon-containing auxiliary materials fall into the small molten pools 11. Some of the carbon in the carbon-containing auxiliary materials dissolves in the steel slag. The carbon in the molten steel, slag, and carbon-containing auxiliary materials reacts with the injected oxygen and unstable oxides in the slag to generate CO and CO2 gases, which overflow and react with the slag on the small molten pools to form foamy slag.

[0034] Appendix Figure 3 This diagram illustrates how multiple small molten pools outside the three-phase electrodes expand and converge into an initial large molten pool after the electric arc furnace is energized and heated through the well. As the electric arc furnace continues to be energized, the scrap steel melts continuously due to the electrode heating effect. Multiple small molten pools 11 near electrode 1 expand and converge, and an initial large molten pool 12 is first formed near the three-phase electrode 1. During this stage, foamy slag is continuously formed, and the coverage area of ​​the foamy slag expands as the molten pool expands.

[0035] Continue electrifying until the scrap steel is completely melted. After the initial large molten pool forms for 5-10 minutes, it expands further. Add 10-20 kg / t of lime and 10-20 kg / t of lightly calcined dolomite to the pool in three separate additions, each 3-8 minutes apart. During this process, the added slag continuously melts and reacts with the gases escaping from the pool to form foamy slag, which eventually covers the entire molten pool.

[0036] Throughout the smelting process, carbon-containing auxiliary materials are continuously added and oxygen is injected. The amount of carbon-containing auxiliary materials added is 50-100 kg / min, the particle size is 3-30 mm, the carbon content is not less than 50%, the moisture content is not more than 0.5%, and the oxygen injection rate is 60-120 Nm. 3 / min.

Claims

1. A smelting process for small-pool and multi-pool electric arc furnaces, characterized in that: Follow these steps: ①After tapping steel from the electric arc furnace, add 200-500 kg of lime, 50-200 kg of lightly calcined dolomite and scrap steel to the remaining slag surface in sequence; ② After the electric arc furnace is powered on through the well, carbon-containing auxiliary materials are continuously added near the three-phase electrodes before the scrap steel is melted and cleared. The addition amount is 50-100 kg / min, and oxygen is injected using an oxygen lance. ③ After the electrode penetration is completed, multiple small molten pools are formed near the three-phase electrodes at the bottom of the electric arc furnace. At the same time, the added carbon-containing auxiliary materials fall onto the slag surface of the small molten pools, and the CO and CO2 gases generated by the chemical reaction are released. The carbon-containing auxiliary materials and slag react on the small molten pools to form foamy slag. As the power continues to be supplied, the electrodes heat the scrap steel and continuously melt it. The multiple small molten pools near the three-phase electrodes continue to expand and converge, forming an initial large molten pool near the three-phase electrodes. During this stage, foamy slag is continuously formed, and the coverage area of ​​the foamy slag continues to expand as the molten pools grow. ④ Continue to power on the scrap steel until it is melted and clear. After the initial large molten pool is formed for 5-10 minutes, add 10-20 kg / t of lime and 10-20 kg / t of lightly calcined dolomite to the molten pool in three batches, with an interval of 3-8 minutes between each batch. During this process, the slag added will continuously melt and react with the gas overflowing from the molten pool to continuously form foam slag. Finally, the foam slag will cover the entire molten pool.

2. The electric arc furnace smelting process for small and multiple molten pools according to claim 1, characterized in that: In step ②, the carbon-containing auxiliary material added near the three-phase electrodes has a particle size of 3-30mm, a carbon content of not less than 50%, and a moisture content of not more than 0.5%.

3. The electric arc furnace smelting process for small and multiple molten pools according to claim 1, characterized in that: In step ②, the oxygen injection rate is 60-120 Nm. 3 / min.

4. The electric arc furnace smelting process for small and multiple molten pools according to claim 1, characterized in that: In step ②, carbon-containing auxiliary materials are added near the three-phase electrodes through the feeding port on the furnace cover of the electric arc furnace.

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