A method for increasing the amount of metallized pellets

Abstract

This invention proposes a method to increase the amount of metallized pellets used, comprising: Step 1, screening materials with a metallization rate of 80% or higher for use as scrap steel; Step 2, loading metallized pellets with a metallization rate ≥80% and scrap steel into a scrap steel bale in a fixed pattern; Step 3, pre-treating the material in an electric furnace to prevent molten steel from remaining in the furnace, thus preventing a violent carbon-oxygen reaction and large-scale splashing when the metallized pellets fall into the molten steel and are subsequently heated; Step 4, placing the scrap steel and metallized pellets from the scrap steel bale into the electric furnace, and then applying electricity to melt the scrap steel and metallized pellets in the furnace; Step 5, adding molten iron during the middle stage of smelting to assist in melting and reducing FeO in the metallized pellets; Step 6, after all the scrap steel and metallized pellets in the electric furnace have melted, proceeding to the conventional smelting process for normal smelting. This invention can increase the amount of metallized pellets used in high-power or ultra-high-power electric furnaces.

Description

Technical Field

[0001] This invention belongs to the field of electric furnace smelting technology in the steel industry, and particularly relates to a method for increasing the amount of metallized pellets. Background Technology

[0002] Currently, the capacity of rotary hearth furnaces to process solid waste is gradually improving, and how to efficiently utilize metallized pellets has become a new key research focus.

[0003] Metallized pellets are produced in a rotary hearth furnace by batching, mixing, pelletizing, drying, and high-temperature reduction of solid waste generated during steelmaking and ironmaking processes (such as blast furnace sludge, some blast furnace dust, electric furnace ash, converter ash, converter sludge, sintering dust, etc.) to create spherical materials that meet smelting requirements. Currently, metallized pellets are mainly used as coolants and slag-forming agents in converters and electric furnaces. However, most electric furnaces are now high-power or ultra-high-power furnaces, which have eliminated the reduction period and cannot use large quantities of metallized pellets. The usage of metallized pellets is far lower than the annual output of rotary hearth furnaces, resulting in large stockpiles of metallized pellets in warehouses, which can only be sold off at low prices.

[0004] There is currently a patent for a method of direct steelmaking from cold-solidified pellets (application number CN95104977.1). This method is mainly for electric furnaces with a reduction period and cold-solidified pellets mixed with iron concentrate, and is not applicable to high-power or ultra-high-power electric furnaces. There is also a patent for a method of slag formation from cold-solidified pellets in a continuous steelmaking electric furnace (application number 201310004042.8). This method is mainly used for slag formation, with a dosage of about 6 kg / t, which is too small. Summary of the Invention

[0005] The purpose of this invention is to provide a method for increasing the amount of metallized pellets used, enabling the large-scale application of metallized pellets in high-power or ultra-high-power electric furnaces. To achieve the above objective, the following technical solution is adopted:

[0006] A method for increasing the amount of metallized pellets includes the following steps:

[0007] Step 1: Classify the metallized pellets according to their metallization rate. Those with a metallization rate below 70% are used as slag-reducing agents; those with a metallization rate between 70% and 80% are used as coolants; select metallized pellets with a metallization rate above 80% for later use.

[0008] Step 2: Load the metallized pellets with a metallization rate of ≥80% and the scrap steel into the scrap steel bag for transfer;

[0009] Step 3: Electric furnace pretreatment to ensure no molten steel remains in the electric furnace, preventing metallized pellets from falling into the molten steel and causing a carbon-oxygen reaction during subsequent heating, which could lead to splashing.

[0010] Step 4: Place the scrap steel and metallized pellets from the scrap steel bale into the electric furnace, and then turn on the power to melt the scrap steel and metallized pellets in the electric furnace;

[0011] Step 5: During the middle stage of smelting, molten iron is added to the electric furnace to assist in melting and reducing FeO in the metallized pellets;

[0012] Step 6: After visually inspecting the furnace door to ensure that all the scrap steel and metallized pellets in the electric furnace have melted, the process begins.

[0013] Preferably, the metallized pellets are pellets with a high metallization rate.

[0014] Preferably, the specific process in step 2 is as follows: first, a layer of scrap steel is placed, then a layer of metallized pellets is placed, and then the process is repeated.

[0015] Preferably, the steel ladle is a scrap steel ladle.

[0016] Preferably, the electric furnace is a high-power electric furnace or an ultra-high-power electric furnace.

[0017] Preferably, the method and timing of adding molten iron are determined as follows: the molten iron is added in batches; when the scrap steel is visually observed to be in a semi-molten state, molten iron is added to assist the scrap steel in melting and forming a molten pool.

[0018] Compared with existing technologies, the advantages of this invention are: it categorizes metallized pellets, improving the utilization rate of high-metallization-rate metallized pellets; the metallized pellets are fused with scrap steel during the early stage of electric arc furnace smelting, and react with carbon in the molten iron during the middle stage, increasing Fe recovery. By screening the metallization rate of the metallized pellets and changing the feeding method, metallized pellets can be applied in large quantities in high-power or ultra-high-power electric arc furnaces. This method achieves a metallized pellet consumption of over 80 kg / t of steel, meaning that for a 100t electric arc furnace, each furnace uses 8t of metallized pellets. Attached Figure Description

[0019] Figure 1 This is a schematic diagram showing the loading method for scrap steel and metallized pellets.

[0020] Figure 2 This diagram shows the main oxygen flow rate of the oxygen lance, the total number of oxygen lances at the furnace door, and the total power consumption.

[0021] Figure 3 This is a picture of a scrap steel bale.

[0022] Figure 4 This is a diagram showing the distribution of oxygen lances in an electric furnace and the location of the vertical shaft.

[0023] Among them, 1-scrap steel layer, 2-metallized pellet layer, 3-scrap steel bale. Detailed Implementation

[0024] The method for increasing the amount of metallized pellets according to the present invention will now be described in more detail with reference to the schematic diagrams, which illustrate preferred embodiments of the invention. It should be understood that those skilled in the art can modify the invention described herein while still achieving its advantageous effects. Therefore, the following description should be understood as being of general knowledge to those skilled in the art and is not intended to limit the invention.

[0025] like Figures 1-4 As shown, a method for increasing the amount of metallized pellets includes the following steps:

[0026] Step 1: Classify the metallized pellets. Those with a metallization rate of less than 70% are used as slag-reducing agents; those with a metallization rate between 70% and 80% are used as coolants; and those with a metallization rate of more than 80% are used as scrap steel.

[0027] Step 2: Load the metallized pellets (≥80% metallization rate) and scrap steel into the scrap steel bag 3 for transfer. Specifically, first add a layer of scrap steel, then a layer of metallized pellets, and repeat the process. For example... Figure 1 As shown, a certain amount of scrap steel forms a scrap steel layer 1, and a certain amount of metallized pellets forms a metallized pellet layer 2.

[0028] The above operations serve two purposes: first, to prevent the metallized pellets from clustering together and agglomerating during subsequent melting, and to disperse and spread the metallized pellets to facilitate melting; second, to allow the metallized pellets to come into contact with the molten iron in stages as the scrap steel melts, thereby reducing the risk of explosive splashing.

[0029] Step 3: Pre-treat the electric furnace to ensure no molten steel remains inside. This prevents metallized pellets from falling into the molten steel and causing a violent carbon-oxygen reaction that could lead to widespread splashing during subsequent heating. The melting temperature of this electric furnace is between 1520°C and 1660°C; it is a high-power or ultra-high-power electric furnace.

[0030] Step 4: Place the scrap steel and metallized pellets from the scrap steel bale into the electric furnace, and then turn on the power to melt the scrap steel and metallized pellets in the steel bale.

[0031] Step 5: In the middle stage of smelting, molten iron is added to the electric furnace to accelerate the formation of the molten pool and assist in melting the scrap steel and metallized pellets. The FeO after the metallized pellets are molten reacts with the C in the molten iron as follows.

[0032] FeO + C → Fe + CO↑

[0033] Preferably, the method and timing of adding molten iron are as follows: molten iron is added in batches; when the scrap steel is visually inspected to be in a semi-molten state, molten iron is added to assist in melting the scrap steel and forming a molten pool.

[0034] Step 6: After all the scrap steel and metallized pellets in the ladle have melted, proceed to the next smelting process. That is, continue smelting into qualified molten steel according to standard operating procedures.

[0035] The above are merely preferred embodiments of the present invention and do not constitute any limitation on the present invention. Any equivalent substitutions or modifications made by those skilled in the art to the technical solutions and content disclosed in the present invention without departing from the scope of the present invention shall be deemed to have remained within the protection scope of the present invention.

Claims

1. A method for increasing the amount of metallized pellets, characterized in that, Includes the following steps: Step 1: Classify the metallized pellets according to their metallization rate. Those with a metallization rate below 70% are used as slag-reducing agents; those with a metallization rate between 70% and 80% are used as coolants; select metallized pellets with a metallization rate above 80% for later use. Step 2: Load the metallized pellets with a metallization rate of ≥80% and the scrap steel into the scrap steel bag for transfer; The specific process is as follows: first, a layer of scrap steel is placed in, then a layer of metallized pellets is placed in, and then the process is repeated. Step 3: Electric furnace pretreatment to ensure no molten steel remains in the electric furnace, preventing metallized pellets from falling into the molten steel and causing a carbon-oxygen reaction during subsequent heating, which could lead to splashing. Step 4: Place the scrap steel and metallized pellets from the scrap steel bale into the electric furnace, and then turn on the power to melt the scrap steel and metallized pellets in the electric furnace. Step 5: During the middle stage of smelting, molten iron is added to the electric furnace to assist in melting and reducing FeO in the metallized pellets; Determine the method and timing of adding molten iron: Add it in batches; add molten iron when the scrap steel is in a semi-molten state to help melt the scrap steel and form a molten pool; Step 6: After visually inspecting the furnace door to ensure that all the scrap steel and metallized pellets in the electric furnace have melted, the process begins.

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