A method for temperature adjustment of molten steel in a ladle

Abstract

A kind of temperature adjusting method for liquid steel in ladle, comprising the following steps: step one: calculate the temperature Q of residual amount;Residual temperature Q=argon before the temperature C1 of liquid steel in ladle-target temperature C2 before continuous casting of liquid steel in ladle-environment natural cooling temperature C3 reduced by argon cooling;Step two: calculate the required scrap steel amount X;According to the composition of liquid steel in ladle, to select the type of scrap steel;Required scrap steel amount X=K / I;Wherein, K is the heat required for the liquid steel in ladle to reduce Q degree;I is the heat that can be absorbed after one kilogram of scrap steel is completely melted in liquid steel;Step three: put the required weight of scrap steel into liquid steel;Step four: real-time monitoring of liquid steel temperature in ladle;After the detection temperature reaches the target temperature C2 before continuous casting, the overhead crane is lifted, and the ladle is transferred to the continuous casting process.

Description

Technical Field

[0001] This invention relates to a temperature control method, and more particularly to a method for controlling the temperature of molten steel in a ladle to meet specific requirements, belonging to the field of metallurgical technology. Background Technology

[0002] In the smelting process, one step involves refining the molten steel in the ladle. This refining process adjusts the temperature and composition, and removes inclusions. Due to time constraints in the production process, the refining time in the ladle is limited. Therefore, the temperature of the molten steel in the ladle needs to be reduced to a suitable range before it is transferred to the continuous casting workshop. However, the cooling effect of ambient heat absorption and argon gas absorption on the molten steel is limited. When the difference between the argon-prepared temperature and the target temperature is too large, exceeding the adjustment range of ambient and argon gas absorption, the molten steel cannot be adjusted to the target temperature in time, thus failing to meet the temperature requirements for continuous casting. When the difference between the argon-prepared temperature and the target temperature is too large, the methods used on-site... The current method involves forcibly cooling the molten steel by adding scrap billets into the ladle. However, this method is uncontrollable and has many drawbacks. After being added to the ladle, the scrap billets sink to the bottom, causing the temperature at the bottom of the ladle to drop rapidly, affecting the ladle's self-opening rate. Furthermore, adding too many scrap billets can cause the molten steel temperature to drop too low, which is also detrimental to continuous casting production. In addition, there are many types of scrap billets with different compositions. Adding too many scrap billets that do not match the composition of the molten steel can have an adverse effect on the composition of the molten steel. Therefore, a method for regulating the temperature of molten steel is needed, which should be able to precisely adjust the temperature of the molten steel in the ladle to a suitable range and minimize the adverse effects on the composition of the molten steel. Summary of the Invention

[0003] The purpose of this invention is to overcome the shortcomings of the prior art and provide a method for temperature control of molten steel in a ladle, which can accurately adjust the temperature of the molten steel in the ladle and quickly adjust it to a suitable range.

[0004] The problem described in this invention is solved by the following technical solution:

[0005] A method for temperature control of molten steel in a ladle includes the following steps:

[0006] Step 1: Calculate the remaining temperature Q; Remaining temperature Q = Pre-argon temperature of molten steel in ladle C1 - Target temperature of molten steel in ladle before continuous casting C2 - Temperature reduction due to ambient natural cooling plus argon cooling C3;

[0007] Step 2: Calculate the required amount of scrap steel X;

[0008] The type of scrap steel is selected based on the composition of the molten steel in the ladle. If the composition of the molten steel meets the requirements and no alloying is needed, scrap steel with the same composition as the molten steel is selected to adjust the temperature of the molten steel. If the molten steel needs to be alloyed, scrap steel with a higher content of beneficial elements is used to adjust the temperature of the molten steel.

[0009] The required amount of scrap steel X = K / I; where K is the heat required to reduce the Q degree of the molten steel in the ladle;

[0010] I is the amount of heat that one kilogram of scrap steel can absorb after it is completely melted in molten steel;

[0011] Step 3: Add the required weight of scrap steel into the molten steel;

[0012] The large modular scrap steel column is cylindrical in shape, and each weighs 50KG.

[0013] The small modular scrap steel column is cylindrical in shape and weighs 5KG each.

[0014] The modular scrap steel sheets are long and thin, and each weighs 1 kg.

[0015] The number of large-module scrap steel columns to be deployed is W1, the number of small-module scrap steel columns is W2, and the number of module scrap steel sheets is W3. [X] = 50W1 + 5W2 + W3.

[0016] Where [X] represents the largest integer not exceeding X;

[0017] The bottom of the crane's hook is connected to a disc, and multiple lifting rings are evenly arranged on the bottom surface of the disc. Large-module scrap steel columns are connected to the lifting rings at the bottom of the disc via steel rods, and the large-module scrap steel columns are evenly distributed in the center of the bottom surface of the disc. Small-module scrap steel columns are connected to the lifting rings at the bottom of the disc via steel rods, and the small-module scrap steel columns are evenly distributed along the outer ring area of ​​the large-module scrap steel columns.

[0018] Both large and small modular scrap steel columns are suspended above the molten steel in the ladle. Hooks are installed at both ends of the steel column, and the hook at the top of the steel column is connected to the crane hook. The hook at the bottom of the steel column is connected to the lifting ring at the top of the large or small modular scrap steel column.

[0019] The scrap steel sheets from each module were directly fed into the molten steel in the ladle;

[0020] Step 4: Monitor the temperature of the molten steel in the ladle in real time;

[0021] After the scrap steel is put into the ladle, the temperature of the molten steel in the ladle is checked every 15 seconds. Once the temperature reaches the target temperature C2 before continuous casting, the overhead crane lifts the hook and transfers the ladle to the continuous casting process.

[0022] The method for calculating C3 in the above-mentioned temperature control method for molten steel in a ladle is as follows:

[0023] Within 120 seconds of argon gas being introduced into the ladle, the temperature of the molten steel was measured and recorded every 15 seconds. The temperature decrease value within each 15 seconds divided by 15 is the cooling rate. The average value of the cooling rate of each group is a.

[0024] The allowable cooling time for molten steel in the ladle is T. 总 During the cooling period T 总 During this period, the temperature reduction caused by natural cooling of the environment plus argon gas cooling is C3 = aT. 总 .

[0025] The above-mentioned temperature control method for molten steel in a ladle

[0026] The calculation method for K is as follows:

[0027] It can be seen that the average specific heat of molten steel in its liquid or gaseous state is 0.8368 kJ / (kg·K);

[0028] The weight of the molten steel in the ladle is M, and the unit of M is KG;

[0029] K=0.8368MQ.

[0030] The above-mentioned temperature control method for molten steel in a ladle

[0031] The calculation method for I is as follows:

[0032] I=0.699(U-25)+271.96kJ+0.8368(C2-U)

[0033] It is known that the melting point of pure iron is 1536℃;

[0034] The solid equilibrium specific heat of scrap steel is 0.699 kJ / (kg·K);

[0035] The latent heat of fusion of scrap steel is 271.96 kJ / kg;

[0036] The average specific heat of scrap steel in its liquid or gaseous state is 0.8368 kJ / (kg·K);

[0037] The temperature of scrap steel is 25℃.

[0038] The melting point of scrap steel is U; U = 1536 - H, where H is the decrease in the melting point of iron due to the various elements contained in the scrap steel.

[0039] The above-mentioned temperature control method for molten steel in a ladle

[0040] H is calculated as follows:

[0041] Among the elements contained in scrap steel, the elements that mainly affect the melting point of iron are carbon (C), silicon (Si), manganese (Mn), phosphorus (P), and sulfur (S).

[0042] The following are the numerical values ​​of how various elements dissolved in iron from scrap steel reduce the melting point of iron:

[0043] Adding 1% carbon (C) lowers the melting point of iron by 65°C; adding 1% silicon (Si) lowers the melting point of iron by 8°C; adding 1% manganese (Mn) lowers the melting point of iron by 5°C; adding 1% phosphorus (P) lowers the melting point of iron by 30°C; adding 1% sulfur (S) lowers the melting point of iron by 25°C.

[0044] The dissolution of nitrogen, hydrogen, and oxygen lowers the melting point of iron by 6°C;

[0045] Assume the content of carbon (C) in the scrap steel is N1%, silicon (Si) is N2%, manganese (Mn) is N3%, phosphorus (P) is N4%, and sulfur (S) is N5%.

[0046] H = 65N1 + 8N2 + 5N3 + 30N4 + 25N5 + 6.

[0047] In the above-mentioned method for temperature control of molten steel in a ladle, the large module scrap steel column, the small module scrap steel column, and the module scrap steel sheet are all pre-cast.

[0048] Cylindrical molds and elongated sheet molds are made. Then, large pieces of scrap steel are melted and poured into the cylindrical molds and elongated sheet molds for cooling and solidification. After solidification, the modular scrap steel columns and modular scrap steel sheets are removed. The cast modular scrap steel columns are standard cylinders. The large modular scrap steel columns weigh 50KG, and the small modular scrap steel columns weigh 5KG. The modular scrap steel sheets are elongated sheets and weigh 1KG.

[0049] This invention regulates the temperature of molten steel by suspending scrap steel for loading, avoiding the problem of molten steel splashing caused by manual handling and loading, as well as preventing scrap steel from sinking to the bottom, and further avoiding affecting the self-opening rate of the ladle; by melting the scrap steel and recasting it into modular scrap steel, the amount of scrap steel loaded is precisely controlled, ensuring the controllability of temperature drop regulation, and the modular scrap steel is more easily dissolved in molten steel, which greatly improves the dissolution rate compared to the previous whole piece of scrap steel;

[0050] In actual production, the temperature at the upper end of the molten steel ladle is higher than that at the lower end, so the scrap steel dissolves faster in the upper layer of the molten steel.

[0051] Regular scrap steel has different shapes and sizes. During the process of adding scrap steel, the scrap steel falls randomly in the ladle and the melting time is inconsistent. After being added to the ladle, the scrap steel will sink to the bottom and not melt easily, resulting in the bottom temperature of the ladle being too low and affecting the ladle's self-opening rate.

[0052] During the steel production process, various types of scrap steel are generated, so various types of modular scrap steel can be available. This allows for the selection of modular scrap steel with different compositions based on the composition of the molten steel. When the composition of the molten steel meets the standards, scrap steel with the same composition as the molten steel is selected for temperature adjustment to avoid affecting the composition of the molten steel and causing it to become unqualified. When a certain component in the molten steel is insufficient, beneficial elements are used to supplement the missing element in the molten steel, thereby reducing alloy costs. Detailed Implementation

[0053] This invention includes the following steps:

[0054] Step 1: Calculate the residual temperature Q; After the ladle is loaded with molten steel, it needs to be argon-blown before being transferred to the continuous casting process. The time between receiving the molten steel in the ladle and transferring it to the continuous casting process is limited; this time, which is the allowable cooling time of the molten steel in the ladle, is T. 总 The molten steel in the ladle needs to be kept at T as close to the surface as possible. 总 The molten steel is transferred within a certain time frame. During this period, the molten steel in the ladle gradually cools down due to the heat absorption of argon gas and the environment. However, sometimes the cooling efficiency of the environment and argon gas is insufficient to reach the required temperature within the specified time frame. 总 The molten steel needs to be cooled to the required temperature range within a short period of time, so additional cooling is required; the additional cooling method used in this invention is to add scrap steel.

[0055] The so-called residual temperature Q is the temperature margin that cannot be absorbed by the heat absorbed by the environment and argon gas. This part of the residual temperature heat is solved by the heat absorbed by the melting of scrap steel. Residual temperature Q = Pre-argon temperature of molten steel in ladle C1 - Target temperature of molten steel in ladle before continuous casting C2 - Temperature reduction C3 due to natural cooling of the environment plus argon gas cooling.

[0056] Based on the line graph of the heat absorption of the environment and argon gas on the molten steel in the ladle during daily production, it can be seen that the cooling effect of the combination of environment and argon gas on the molten steel is approximately a straight line on the line graph with time as the horizontal axis and temperature as the vertical axis. Therefore, the temperature of the molten steel can be monitored in the first 120 seconds after the scrap steel is added, and the future cooling rate can be calculated based on the temperature change in the first 120 seconds. This allows us to know the amount of heat absorbed by the environment and argon gas during the entire cooling process. Then, based on the total temperature reduction required for the molten steel, we can calculate the required temperature reduction of the scrap steel.

[0057] Step 2: Calculate the required amount of scrap steel X;

[0058] The type of scrap steel is selected based on the composition of the molten steel in the ladle. If the composition of the molten steel meets the standard and no additional alloy is needed, scrap steel with the same composition as the molten steel is selected to adjust the temperature of the molten steel. If the molten steel needs to be added with alloy, scrap steel with a higher content of beneficial elements is used to adjust the temperature of the molten steel. This method reduces the amount of subsequent alloy addition and thus solves the production cost problem.

[0059] The required amount of scrap steel X = K / I; where K is the heat required to reduce the Q degree of the molten steel in the ladle;

[0060] I is the amount of heat that one kilogram of scrap steel can absorb after it is completely melted in molten steel;

[0061] The required weight of scrap steel can be determined by dividing the total heat by the heat that one kilogram of scrap steel can absorb.

[0062] Step 3: Add the required weight of scrap steel into the molten steel;

[0063] The large modular scrap steel column is cylindrical in shape, and each weighs 50KG.

[0064] The small modular scrap steel column is cylindrical in shape and weighs 5KG each.

[0065] The cylindrical shape increases the surface area of ​​the scrap steel that can contact the molten steel when it is immersed in the molten steel, allowing it to melt as quickly as possible.

[0066] The modular scrap steel sheets are long and thin, with each sheet weighing 1 kg. The lightweight modular scrap steel sheets can melt quickly as they fall into the molten steel without sinking to the bottom. The combination of modular scrap steel sheets of different weights ensures that the weight of the scrap steel being fed in is as accurate as possible.

[0067] The number of large-module scrap steel columns to be deployed is W1, the number of small-module scrap steel columns is W2, and the number of module scrap steel sheets is W3. [X] = 50W1 + 5W2 + W3.

[0068] When calculating the amount of scrap steel in each module, first calculate W1, take the maximum value of W1, and then supplement the difference between W1 and [X] by the scrap steel columns of small modules and the scrap steel sheets of modules; where [X] represents the largest integer not exceeding X, and the value after the decimal point of X can be ignored.

[0069] The crane's hook is connected to a disc at its bottom, with multiple lifting rings evenly distributed on the bottom surface of the disc. Large modular scrap steel columns are connected to the lifting rings at the bottom of the disc via steel rods, and these large modular scrap steel columns are evenly distributed in the center of the bottom surface of the disc. The large modular scrap steel columns are first connected to the steel rods under the lifting rings near the center of the disc, and then the lighter small modular scrap steel columns are arranged around the outer ring of the large modular scrap steel columns, ensuring that the center of gravity remains in the center. The small modular scrap steel columns are connected to the lifting rings at the bottom of the disc via steel rods, and these small modular scrap steel columns are evenly distributed along the outer ring of the large modular scrap steel columns. The disc is suspended directly above the ladle without contacting it, and the lower ends of the steel rods are submerged in the molten steel.

[0070] Both large and small scrap steel columns are suspended above the molten steel in the ladle. Hooks are installed at both ends of the steel rods, with the top hook connected to the overhead crane hook and the bottom hook connected to the lifting ring at the top of the large or small scrap steel column. The steel rods have a higher melting point than the scrap steel, so the scrap steel melts into the molten steel first, preventing it from falling to the bottom of the ladle halfway through. Each module of scrap steel is directly dropped into the molten steel in the ladle.

[0071] Step 4: Monitor the temperature of the molten steel in the ladle in real time;

[0072] After scrap steel is fed into the ladle, the temperature of the molten steel inside the ladle is checked every 15 seconds. Once the temperature reaches the target temperature C2 before continuous casting, the overhead crane lifts the hook and transfers the ladle to the continuous casting process. As long as the molten steel temperature meets the standard, it can be immediately transferred to the continuous casting machine without waiting for T. 总 Then proceed with the transfer.

[0073] The calculation method for C3 is as follows:

[0074] Within 120 seconds of argon gas being introduced into the ladle, the temperature of the molten steel is measured and recorded every 15 seconds. The temperature decrease within each 15-second interval is divided by 15 to obtain the cooling rate. The average cooling rate of all groups is 'a'. The allowable cooling time for the molten steel in the ladle is T. 总 During the cooling period T 总 During this period, the temperature reduction caused by natural cooling of the environment plus argon gas cooling is C3 = aT. 总 .

[0075] The calculation method for K is as follows:

[0076] It can be seen that the average specific heat of molten steel in its liquid or gaseous state is 0.8368 kJ / (kg·K);

[0077] The weight of the molten steel in the ladle is M, and the unit of M is KG;

[0078] K = 0.8368MQ; Q represents the temperature that needs to be reduced, and its unit is Celsius. After converting it to Kelvin, since the essence of Q is temperature difference, the value of Q remains unchanged after converting Celsius to Kelvin. Therefore, the value of Q can be directly substituted into 0.8368MQ without conflict.

[0079] The calculation method for I is as follows:

[0080] I=0.699(U-25)+271.96kJ+0.8368(C2-U)

[0081] (U-25) means the temperature increase required for scrap steel to rise from room temperature (25) to its melting temperature (U).

[0082] (C2-U) means the temperature increase required for scrap steel in a liquid state to reach the C2 temperature;

[0083] According to conventional data, the melting point of pure iron is 1536℃;

[0084] The solid equilibrium specific heat of scrap steel is 0.699 kJ / (kg·K);

[0085] The latent heat of fusion of scrap steel is 271.96 kJ / kg;

[0086] The average specific heat of scrap steel in its liquid or gaseous state is 0.8368 kJ / (kg·K);

[0087] The temperature of scrap steel is 25℃.

[0088] The melting point of scrap steel is U; U = 1536 - H, where H is the decrease in the melting point of iron due to the various elements contained in the scrap steel.

[0089] H is calculated as follows:

[0090] Among the elements contained in scrap steel, the main elements that affect the melting point of iron are carbon (C), silicon (Si), manganese (Mn), phosphorus (P), and sulfur (S); each of these elements will lower the melting point of iron when added to it.

[0091] The following are the numerical values ​​of how various elements dissolved in iron from scrap steel reduce the melting point of iron:

[0092] The following data are standard data; each 1% carbon (C) element dissolved lowers the melting point of iron by 65°C; each 1% silicon (Si) element dissolved lowers the melting point of iron by 8°C; each 1% manganese (Mn) element dissolved lowers the melting point of iron by 5°C; each 1% phosphorus (P) element dissolved lowers the melting point of iron by 30°C; each 1% sulfur (S) element dissolved lowers the melting point of iron by 25°C.

[0093] The dissolution of nitrogen, hydrogen, and oxygen lowers the melting point of iron by 6°C;

[0094] Assume the content of carbon (C) in the scrap steel is N1%, silicon (Si) is N2%, manganese (Mn) is N3%, phosphorus (P) is N4%, and sulfur (S) is N5%.

[0095] H = 65N1 + 8N2 + 5N3 + 30N4 + 25N5 + 6; Calculate the melting point based on the selected scrap steel composition;

[0096] The large-module scrap steel column, small-module scrap steel column, and module scrap steel sheet are all pre-cast;

[0097] Before the molten steel in the ladle is cooled down, various types of module scrap steel with different compositions have been prepared and can be taken out as needed;

[0098] The modular scrap steel production process is as follows: Cylindrical molds and long strip molds are made according to the shape of the modular scrap steel. Large pieces of scrap steel are then melted and poured into the cylindrical and long strip molds for cooling and solidification. After solidification, the modular scrap steel columns and sheets are removed. Modular scrap steel columns cast from scrap steel of the same composition are arranged together. The cast modular scrap steel columns are standard cylinders, with large columns weighing 50 kg and small columns weighing 5 kg. The modular scrap steel sheets are long strips, weighing 1 kg. Example 1:

[0099] The pre-argon temperature (C1) of the molten steel in the ladle is 1650℃, and the weight of the molten steel in the ladle is 95000KG. The chemical composition of the molten steel in the ladle before argon ... 总 It takes 8 minutes, which is 8 * 60 = 480 seconds;

[0100] The temperature of the molten steel at 0s is 1650℃; at 15s it is 1649℃; at 30s it is 1648℃; at 45s it is 1647℃; at 60s it is 1646℃; at 75s it is 1646℃; at 90s it is 1645℃; at 105s it is 1644℃; and at 120s it is 1643℃. Calculate the average cooling rate for each group, a = 7 / 120.

[0101] C3=aT 总 = (7 / 120)480 = 28;

[0102] Q=C1-C2-C3=1650-1590-28=32℃;

[0103] Based on the composition of the molten steel in the ladle, the scrap steel selected is Q235B1 modular scrap steel; the composition of Q235B1 modular scrap steel is C: 0.06%, Mn: 0.73%, Si: 0.06%, P: 0.019%, S: 0.014%;

[0104] Calculate the heat K required to reduce the Q degree of molten steel in the ladle;

[0105] K=0.8368MQ=0.8368*95000*32=2543872kJ;

[0106] Calculate the heat I that one kilogram of scrap steel can absorb after it is completely melted in molten steel;

[0107] H=65N1+8N2+5N3+30N4+25N5+6=65*0.06+8*0.06+5*0.73+30*0.019+25*0.014+6=14.95;

[0108] The melting point of scrap steel is U = 1536 - H = 1536 - 14.95 = 1521.05.

[0109] I=0.699(U-25)+271.96kJ+0.8368(C2-U)=

[0110] 0.699(1521.05-25)+271.96+0.8368(1590-1521.05)=1375.4;

[0111] Therefore, the required amount of scrap steel is X = K / I = 2543872 / 1375.4 = 1849.55KG;

[0112] [X] = 1849 = 50W1 + 5W2 + W3; therefore, W1 = 36, W2 = 9, and W3 = 4.

[0113] Thirty-six large-module scrap steel columns are evenly distributed in the center of the bottom end face of the disc, and nine small-module scrap steel columns are evenly distributed along the outer ring of the large-module scrap steel columns; four-module scrap steel sheets are directly put into the molten steel in the ladle.

[0114] Then, the temperature of the molten steel is measured every 15 seconds. 465 seconds after the molten steel enters the ladle, the temperature of the molten steel in the ladle reaches the target temperature C2 before continuous casting. Then, the overhead crane lifts the plate and transfers the molten steel in the ladle to the continuous casting process. Thus, the molten steel in the ladle has been successfully temperature-controlled before entering the continuous casting process. Example 2:

[0115] The molten steel in the ladle had an argon-prepared temperature (C1) of 1640℃ and a weight of 93,000 kg. The chemical composition of the molten steel before argon preparation was controlled as follows: C: 0.52%, Mn: 0.20%, Si: 0.02%, P: 0.018%, S: 0.017%; the remainder were unavoidable impurities. The target temperature for this furnace was C2 of 1605℃, and the actual argon-prepared temperature was 35℃ higher than the target.

[0116] Allowable cooling time T for molten steel in ladle 总 It is 9 minutes, which is 9 * 60 = 540 seconds;

[0117] The temperature of the molten steel at 0s is 1640℃; at 15s it is 1639℃; at 30s it is 1638℃; at 45s it is 1638℃; at 60s it is 1637℃; at 75s it is 1636℃; at 90s it is 1635℃; at 105s it is 1635℃; and at 120s it is 1634℃. Calculate the average cooling rate a = 1 / 20 for each group.

[0118] C3=aT 总 = (1 / 20)540 = 27℃;

[0119] Q=C1-C2-C3=1640-1605-27=8℃;

[0120] Based on the composition of the molten steel in the ladle, the scrap steel selected is Q355B modular scrap steel; its composition is C: 0.18%, Mn: 1.25%, Si: 0.23%, P: 0.015%, S: 0.016%.

[0121] Calculate the heat K required to reduce the Q degree of molten steel in the ladle;

[0122] K=0.8368MQ=0.8368*93000*8=622579kJ;

[0123] Calculate the heat I that one kilogram of scrap steel can absorb after it is completely melted in molten steel;

[0124] H=65N1+8N2+5N3+30N4+25N5+6=65*0.18+8*0.23+5*1.25+30*0.015+25*0.016+6=26.64;

[0125] The melting point of scrap steel is U = 1536 - H = 1536 - 26.64 = 1509.36.

[0126] I=0.699(U-25)+271.96+0.8368(C2-U)=

[0127] 0.699(1509.36-25)+271.96+0.8368(1605-1509.36)=1389.55;

[0128] Therefore, the required amount of scrap steel is X = K / I = 622579 / 1389.55 = 448.04;

[0129] [X]=448=50W1+5W2+W3; it can be seen that W1=8, W2=9, W3=3; 8 large modular scrap steel columns are evenly distributed in the center of the bottom end face of the disc, and 9 small modular scrap steel columns are evenly distributed along the outer ring area of ​​the large modular scrap steel columns; 3 modular scrap steel sheets are directly put into the molten steel in the ladle; then the temperature of the molten steel is measured every 15 seconds. 510 seconds after the molten steel enters the ladle, the temperature of the molten steel in the ladle reaches the target temperature C2 before continuous casting. Then the overhead crane lifts the disc and transfers the molten steel in the ladle to the continuous casting process for molten steel transfer; thus, the molten steel in the ladle has undergone successful temperature adjustment before entering the continuous casting process.

[0130] During the temperature adjustment process, the argon flow rate can be appropriately increased to improve the flow rate of molten steel and accelerate the melting speed of the module scrap steel.

Claims

1. A method for temperature control of molten steel in a ladle, characterized in that: Includes the following steps: Step 1: Calculate the remaining temperature Q; Remaining temperature Q = Pre-argon temperature of molten steel in ladle C1 - Target temperature of molten steel in ladle before continuous casting C2 - Temperature reduction due to ambient natural cooling plus argon cooling C3; Step 2: Calculate the required amount of scrap steel X; The type of scrap steel is selected based on the composition of the molten steel in the ladle. If the composition of the molten steel meets the requirements and no alloying is needed, scrap steel with the same composition as the molten steel is selected to adjust the temperature of the molten steel. If the molten steel needs to be alloyed, scrap steel with a higher content of beneficial elements is used to adjust the temperature of the molten steel. The required amount of scrap steel X = K / I; where K is the heat required to reduce the Q degree of the molten steel in the ladle; I is the amount of heat that one kilogram of scrap steel can absorb after it is completely melted in molten steel; Step 3: Add the required weight of scrap steel into the molten steel; The large modular scrap steel column is cylindrical in shape, and each weighs 50KG. The small modular scrap steel column is cylindrical in shape and weighs 5KG each. The modular scrap steel sheets are long and thin, and each weighs 1 kg. The number of large-module scrap steel columns to be deployed is W1, the number of small-module scrap steel columns is W2, and the number of module scrap steel sheets is W3. [X] = 50W1 + 5W2 + W3. Where [X] represents the largest integer not exceeding X; The bottom of the crane's hook is connected to a disc, and multiple lifting rings are evenly arranged on the bottom surface of the disc. Large-module scrap steel columns are connected to the lifting rings at the bottom of the disc via steel rods, and the large-module scrap steel columns are evenly distributed in the center of the bottom surface of the disc. Small-module scrap steel columns are connected to the lifting rings at the bottom of the disc via steel rods, and the small-module scrap steel columns are evenly distributed along the outer ring area of ​​the large-module scrap steel columns. Both large and small modular scrap steel columns are suspended above the molten steel in the ladle. Hooks are installed at both ends of the steel column, and the hook at the top of the steel column is connected to the crane hook. The hook at the bottom of the steel column is connected to the lifting ring at the top of the large or small modular scrap steel column. The scrap steel sheets from each module were directly fed into the molten steel in the ladle; Step 4: Monitor the temperature of the molten steel in the ladle in real time; After the scrap steel is put into the ladle, the temperature of the molten steel in the ladle is checked every 15 seconds. Once the temperature reaches the target temperature C2 before continuous casting, the overhead crane lifts the hook and transfers the ladle to the continuous casting process.

2. The method for temperature control of molten steel in a ladle according to claim 1, characterized in that: The calculation method for C3 is as follows: Within 120 seconds of argon gas being introduced into the ladle, the temperature of the molten steel was measured and recorded every 15 seconds. The temperature decrease value within each 15 seconds divided by 15 is the cooling rate. The average value of the cooling rate of each group is a. The allowable cooling time for molten steel in the ladle is T. 总 During the cooling period T 总 During this period, the temperature reduction caused by natural cooling of the environment plus argon gas cooling is C3 = aT. 总 .

3. The method for temperature control of molten steel in a ladle according to claim 2, characterized in that: The calculation method for K is as follows: It can be seen that the average specific heat of molten steel in its liquid or gaseous state is 0.8368 kJ / (kg·K); The weight of the molten steel in the ladle is M, and the unit of M is KG; K=0.8368MQ.

4. The method for temperature control of molten steel in a ladle according to claim 3, characterized in that: The calculation method for I is as follows: I=0.699(U-25)+271.96kJ+0.8368(C2-U) It is known that the melting point of pure iron is 1536℃; The solid equilibrium specific heat of scrap steel is 0.699 kJ / (kg·K); The latent heat of fusion of scrap steel is 271.96 kJ / kg; The average specific heat of scrap steel in its liquid or gaseous state is 0.8368 kJ / (kg·K); The temperature of scrap steel is 25℃. The melting point of scrap steel is U; U = 1536 - H, where H is the decrease in the melting point of iron due to the various elements contained in the scrap steel.

5. The method for temperature control of molten steel in a ladle according to claim 4, characterized in that: H is calculated as follows: Among the elements contained in scrap steel, the elements that mainly affect the melting point of iron are carbon (C), silicon (Si), manganese (Mn), phosphorus (P), and sulfur (S). The following are the numerical values ​​of how various elements dissolved in iron from scrap steel reduce the melting point of iron: Adding 1% carbon (C) lowers the melting point of iron by 65°C; adding 1% silicon (Si) lowers the melting point of iron by 8°C; adding 1% manganese (Mn) lowers the melting point of iron by 5°C; adding 1% phosphorus (P) lowers the melting point of iron by 30°C; adding 1% sulfur (S) lowers the melting point of iron by 25°C. The dissolution of nitrogen, hydrogen, and oxygen lowers the melting point of iron by 6°C; Assume the content of carbon (C) in the scrap steel is N1%, silicon (Si) is N2%, manganese (Mn) is N3%, phosphorus (P) is N4%, and sulfur (S) is N5%. H = 65N1 + 8N2 + 5N3 + 30N4 + 25N5 + 6.

6. The method for temperature control of molten steel in a ladle according to claim 5, characterized in that: The large-module scrap steel column, small-module scrap steel column, and module scrap steel sheet are all pre-cast; Cylindrical molds and long strip molds are made. Then, large pieces of scrap steel are melted and poured into the cylindrical molds and long strip molds for cooling and solidification. After solidification, the modular scrap steel columns and modular scrap steel sheets are taken out and cast into standard cylindrical shapes.