Method for controlling industrial pure iron continuous casting nozzle nodulation

Abstract

The invention discloses a method for controlling industrial pure iron continuous casting nozzle nodulation, and relates to the technical field of ferrous metallurgy. The method comprises the step of adding rare earth elements Ce and Sm into molten iron before pouring. Rare earth elements Ce and Sm are added into the molten iron before pouring, rare earth inclusions are formed in the molten iron through the synergistic effect of the rare earth elements Ce and Sm, nozzle nodulation caused by aggregation of existing particles in the molten iron is reduced, the adhesion and deposition process of the inclusions on the inner wall of a nozzle is reduced, the inclusions in the continuous casting process are not prone to being attached to the surface of the nozzle, and the continuous casting quality is improved. Therefore, the problem of nozzle nodulation during pouring of industrial pure iron is effectively reduced or eliminated.

Description

Technical Field

[0001] The invention relates to the technical field of iron and steel metallurgy, in particular to a method for controlling nozzle agglomeration of industrial pure iron continuous casting. Background Art

[0002] High-purity industrial pure iron is an alloy with a carbon content of less than 0.04% and an iron content of ≥99.9%. It has the advantages of low coercivity, good electromagnetic properties, high toughness, and good thermal conductivity. It is widely used in magnetic materials, electronic and electrical, new energy batteries, cables, motors, and electric meter solenoid valves. As an important basic raw material in steel materials, the purity of industrial pure iron directly determines the performance of metal products. In the production process of high-end industrial pure iron, continuous casting nozzle nodules often occur. Nozzle nodules make continuous casting difficult, which is a difficulty in the production of industrial pure iron.

[0003] In the continuous casting production process of industrial pure iron, the problem of nozzle nodules has always been one of the key factors restricting production efficiency and cost control. The nozzle is an important channel connecting the tundish and the crystallizer. It is called the throat fortress of continuous casting and is an important part of the clean steel smelting process. Nozzle nodules not only have the risk of blocking the nozzle, but the shedding of nodules will also seriously affect the quality of the ingot, shorten the service life of the nozzle, and increase production costs. The main causes of nozzle nodules during continuous casting can be attributed to: the accumulation of existing inclusions in the molten iron, the infiltration of air near the nozzle causing secondary oxidation of the molten iron and inclusions, the accumulation of reaction products between the nozzle refractory and the molten iron, and insufficient nozzle preheating leading to the accumulation of solid steel. It can be seen that how to control nozzle nodules has become a key technical problem that needs to be solved in the preparation of high-purity iron.

[0004] In order to solve this problem, the industry has conducted a lot of research and attempts. For example, the Chinese patent with publication number CN111940716A discloses a method for preventing the blockage of the nozzle of rare earth steel continuous casting. This method heats the nozzle and the easily blocked parts of the stopper rod, reduces the viscosity of the rare earth inclusions by heating, improves its fluidity, and ensures normal casting by dynamically adjusting the stopper rod. However, the inhibitory effect of nozzle nodules by simply heating the nozzle is poor, and the heating temperature required for different steel grades is different, and the effect on the viscosity of inclusions is also different, and the process control is relatively complicated.

[0005] A Chinese patent with publication number CN109732072B discloses a method for applying like charges to suppress nodules on the inner wall of an immersion nozzle. By applying a stable forward current, the inclusion particles that generate transient charges due to friction cannot adhere to the inner wall of the nozzle due to the repulsive force, so that the sintering and adhesion behavior of the inclusions on the inner wall of the immersion nozzle is limited, thereby suppressing nodules on the nozzle. However, this method is not ideal for removing small-sized and high-density inclusions, and requires a larger current to work.

[0006] The Chinese patent No. 2016200481078 discloses an anti-corrosion immersion nozzle, including a nozzle body, a flow channel for molten iron to flow inside the nozzle body, and an anti-corrosion coating on the outer surface of the nozzle body, which is arranged at the slag line of the nozzle body. The anti-corrosion coating can achieve the same anti-corrosion effect as the original zirconium oxide layer, and can be used with the zirconium oxide layer to increase the service life. However, the cost is high, and it is arranged at the slag line of the outer wall of the nozzle, which has a poor effect on preventing nodules.

[0007] The above methods attempt to solve the problem of nozzle nodules by optimizing nozzle materials, optimizing the inner cavity structure of nozzles, improving the cleanliness of molten iron, blowing argon into nozzles, and applying electromagnetic fields in nozzles. However, as mentioned above, these methods often have problems such as low efficiency, high cost or unstable effect in practical applications, which are difficult to meet the urgent needs of current industrial pure iron continuous casting production for high efficiency, low cost and sustainability.

[0008] Therefore, it is particularly important to develop a method for controlling nozzle nodules in industrial pure iron continuous casting that not only needs to be able to effectively reduce or eliminate the phenomenon of nozzle nodules, improve pouring efficiency and ingot quality, but also needs to have the characteristics of low cost, easy operation, and environmental friendliness to achieve the sustainable development of industrial pure iron continuous casting production. Summary of the invention

[0009] The present invention provides a method for controlling nozzle nodule formation during continuous casting of industrial pure iron. The method can not only effectively reduce or eliminate the nozzle nodule formation problem during the pouring of industrial pure iron, but also has the characteristics of high efficiency, low cost and sustainability, thereby overcoming the problems of poor effect, high cost or unstable effect of existing nozzle nodule formation solutions during the pouring of industrial pure iron, and meeting the requirements of high efficiency, low cost and sustainability in the continuous casting production of industrial pure iron.

[0010] To achieve the above purpose, the technical solution adopted by the present invention is: The method comprises: adding rare earth elements Ce and Sm into molten iron before pouring.

[0011] In the above technical solution, a more specific technical solution may also be: using a nanoporous ceramic filter to filter the slag included in the molten iron.

[0012] Furthermore, the nanoporous ceramic filter has four layers, the through holes of the first layer are 5.5 mm to 6.5 mm in diameter, the second layer is 4 mm to 5 mm in diameter, the third layer is 2.5 mm to 3.5 mm in diameter, the fourth layer is 0.4 mm to 1.5 mm in diameter, and the through holes of each layer are staggered. The nanoporous ceramic filter is prepared by: 2 Pink, A1 2 O 3 Powder and CaO powder according to ZrO 2 45% to 65%, A1 2 O 3 The raw powder accounts for 20% to 30% and the CaO powder accounts for 10% to 25% in the ratio. Then the raw powder is ball-milled into 40nm to 90nm nanocrystalline particles in a high-energy ball mill. Then, the binder polyvinyl butyral and anhydrous ethanol are used to prepare ceramic particle slurry: organic foam polyurethane sponge is used as a porous carrier, and the ceramic slurry is evenly coated on it. After drying, the carrier material is burned out at high temperature to form a porous ceramic filter.

[0013] Furthermore, ZrO 2 -MgO-Cr 2 O 3 -C material is used as the nozzle refractory, and the composition and mass percentage of the nozzle refractory are: C: 15% to 40%, ZrO 2 : 30%~60%, MgO: 5%~15%, Cr 2 O 3 :1%~10%.

[0014] Furthermore, ZrO 2 -MgO-Cr 2 O 3 -C material is used as the nozzle refractory, and the composition and mass percentage of the nozzle refractory are: C: 15% to 40%, ZrO 2 : 30%~60%, MgO: 5%~15%, Cr 2 O 3 :1%~10%.

[0015] Furthermore, ZrO 2 -MgO-Cr 2 O 3 -C material is used as the nozzle refractory, and the composition and mass percentage of the nozzle refractory are: C: 15% to 40%, ZrO 2 : 30%~60%, MgO: 5%~15%, Cr 2 O 3 :1%~10%.

[0016] Furthermore, the total amount of the rare earth elements Ce and Sm added is 0.001% to 0.003% of the mass of the molten iron.

[0017] Furthermore, the mass ratio of the rare earth elements Ce and Sm is 5.5-6.5.

[0018] Due to the adoption of the above technical solution, the present invention has the following beneficial effects compared with the prior art: 1. The present invention can effectively avoid nozzle blockage during the continuous casting of industrial pure iron, thereby ensuring the stability of continuous casting production.

[0019] 2. The present invention adds rare earth elements Ce and Sm to the molten iron (i.e., melt) before pouring, and utilizes the synergistic effect of the two to form rare earth inclusions in the molten iron (i.e., melt), thereby reducing nozzle nodules caused by aggregation of existing particles in the molten iron (i.e., melt), and reducing the adhesion and deposition process of inclusions on the inner wall of the nozzle, so that inclusions in the continuous casting process are not easy to adhere to the nozzle surface, thereby effectively reducing or eliminating the nozzle nodule problem during the pouring of industrial pure iron.

[0020] 3. The present invention adopts a novel nanoporous ceramic filter to filter the slag inclusions in the molten iron (i.e., melt), thereby improving the cleanliness of the molten iron (i.e., melt), and the filter cooperates with the purification effect of rare earth elements to greatly improve the cleanliness of the molten iron (i.e., melt), thereby inhibiting nozzle nodules, thereby further improving, reducing or eliminating the nozzle nodule problem during the pouring of industrial pure iron.

[0021] 4. The present invention adopts ZrO 2 -MgO-Cr 2 O 3 -C composite material is used as the refractory material for the nozzle. This material is not easy to react with molten iron, which can reduce the aggregation of reaction products between the nozzle refractory material and molten iron, and reduce the adhesion and deposition of inclusions on the surface of the refractory material, thereby further preventing the nozzle from nodule blockage: when the MgO content in the nozzle material is lower than 5%, the wettability between the nozzle and molten iron is poor, inclusions are easy to adhere, which is not conducive to inhibiting the nodule phenomenon; when the MgO content exceeds 15%, the heat shock resistance of the refractory material deteriorates, and peeling cracks cannot be avoided, so the MgO content is controlled at 5% to 15%; when the C content is greater than 40%, decarburization reaction is likely to occur, resulting in a decrease in the surface quality of the nozzle, which is more conducive to the adhesion of inclusions to the inner wall of the nozzle.

[0022] 5. The present invention limits the total mass percentage of rare earth elements Ce and Sm added to: 0.001% ~ 0.003%, which can purify molten iron (i.e., melt) to the greatest extent through appropriate addition ratio: rare earth elements Ce and Sm are used as purifiers. When the total mass percentage of added exceeds 0.003%, they themselves will be difficult to remove as impurities, reducing the purity of the molten iron. When the total mass percentage of rare earth added is lower than 0.001%, the impurity removal effect is poor; the mass ratio of rare earth elements Ce and Sm is 5.5 ~ 6.5: when the mass ratio of rare earth elements Ce and Sm is lower than 5.5, the cost of purifying molten iron (i.e., melt) is relatively high; when the mass ratio of Ce and Sm is higher than 6.5, the synergistic impurity removal effect of the two is poor. DETAILED DESCRIPTION

[0023] The present invention is further described in detail below with reference to examples; The nanoporous ceramic filter involved in the following embodiments has four layers, the through-holes of the first layer of the filter sheet have a pore size of 5.5 mm to 6.5 mm, the pore size of the second layer of the filter sheet has a pore size of 4 mm to 5 mm, the pore size of the third layer of the filter sheet has a pore size of 2.5 mm to 3.5 mm, and the pore size of the fourth layer of the filter sheet has a pore size of 0.4 mm to 1.5 mm, and the through-holes of each layer are staggered; The nanoporous ceramic filter is prepared by: 2 Pink, A1 2 O 3 Powder and CaO powder according to ZrO 2 45% to 65%, A1 2 O 3 The raw powder accounts for 20% to 30% and the CaO powder accounts for 10% to 25% in the ratio. Then the raw powder is ball-milled into 40nm to 90nm nanocrystalline particles in a high-energy ball mill. Then, the binder polyvinyl butyral and anhydrous ethanol are used to prepare ceramic particle slurry: organic foam polyurethane sponge is used as a porous carrier, and the ceramic slurry is evenly coated on it. After drying, the carrier material is burned out at high temperature to form a porous ceramic filter.

[0024] Example 1 In the continuous casting process of industrial pure iron, 0.00085% of rare earth element Ce and 0.00015% of rare earth element Sm by mass of molten iron are added to the molten iron (i.e., melt) before pouring, stirred evenly, and then sent to the nozzle for pouring. The pouring superheat is 30°C, the pulling speed is 1.0m / min, and the diameter of the immersion nozzle is 45mm.

[0025] Example 2 In the continuous casting process of industrial pure iron, 0.00085% of rare earth element Ce by mass and 0.00015% of rare earth element Sm by mass are added to the molten iron (i.e., melt) before pouring, and stirred evenly. Then, the slag in the molten iron is filtered out using a nanoporous ceramic filter, and then sent to the nozzle for pouring. The pouring superheat is 30°C, the pulling speed is 1.0m / min, and the diameter of the immersion nozzle is 45mm.

[0026] Example 3 In the continuous casting process of industrial pure iron, 0.00085% of rare earth element Ce and 0.00015% of rare earth element Sm are added to the molten iron (i.e., melt) before pouring, stirred evenly, and then sent to the nozzle for pouring. The pouring superheat is 30°C, the casting speed is 1.0m / min, and the diameter of the immersion nozzle is 45mm. Among them, ZrO 2 -MgO-Cr 2 O 3 -C material is used as nozzle refractory material, and its composition and component mass percentage are: C: 35%, ZrO 2 : 45%, MgO: 10%, Cr 2 O 3 :5%.

[0027] Example 4 In the continuous casting process of industrial pure iron, 0.00085% of rare earth element Ce and 0.00015% of rare earth element Sm by mass of molten iron are added to the molten iron (i.e., melt) before pouring, and the mixture is stirred evenly. Then, the slag in the molten iron is filtered out by a nanoporous ceramic filter, and then the molten iron is sent to the nozzle for pouring. The pouring superheat is 30°C, the pulling speed is 1.0m / min, and the diameter of the immersion nozzle is 45mm. Among them, ZrO2-MgO-Cr2O3-C material is used as the nozzle refractory material, and its composition and component mass percentage are: C: 35%, ZrO 2 : 45%, MgO: 10%, Cr 2 O 3 :5%.

[0028] Example 5 In the continuous casting process of industrial pure iron, 0.00254% of rare earth element Ce and 0.00046% of rare earth element Sm by mass of molten iron are added to the molten iron (i.e., melt) before pouring, stirred evenly, and then sent to the nozzle for pouring. The pouring superheat is 30°C, the pulling speed is 1.0m / min, and the diameter of the immersion nozzle is 45mm.

[0029] Example 6 In the continuous casting process of industrial pure iron, 0.00087% of rare earth element Ce and 0.00013% of rare earth element Sm by mass of molten iron are added to the molten iron (i.e., melt) before pouring, stirred evenly, and then sent to the nozzle for pouring. The pouring superheat is 30°C, the pulling speed is 1.0m / min, and the diameter of the immersion nozzle is 45mm.

[0030] Example 7 In the continuous casting process of industrial pure iron, 0.0026% of rare earth element Ce and 0.0004% of rare earth element Sm by mass of molten iron are added to the molten iron (i.e., melt) before pouring, stirred evenly, and then sent to the nozzle for pouring. The pouring superheat is 30°C, the pulling speed is 1.0m / min, and the diameter of the immersion nozzle is 45mm.

[0031] Comparative Example 1 In the continuous casting process of industrial pure iron, molten iron that has been smelted, refined, etc. (ie, the "molten iron before pouring" mentioned in Examples 1 to 4) is directly delivered to the nozzle for pouring.

[0032] Comparative Example 2 In the continuous casting process of industrial pure iron, 0.00076% of rare earth element Ce and 0.00014% of rare earth element Sm by mass of molten iron are added to the molten iron (i.e., melt) before pouring, stirred evenly, and then sent to the nozzle for pouring. The pouring superheat is 30°C, the pulling speed is 1.0m / min, and the diameter of the immersion nozzle is 45mm.

[0033] Comparative Example 3 In the continuous casting process of industrial pure iron, 0.00338% of rare earth element Ce and 0.00062% of rare earth element Sm by mass of molten iron are added to the molten iron (i.e., melt) before pouring, stirred evenly, and then sent to the nozzle for pouring. The pouring superheat is 30°C, the pulling speed is 1.0m / min, and the diameter of the immersion nozzle is 45mm.

[0034] Comparative Example 4 In the continuous casting process of industrial pure iron, 0.00089% of rare earth element Ce and 0.00011% of rare earth element Sm by mass of molten iron are added to the molten iron (i.e., melt) before pouring, stirred evenly, and then sent to the nozzle for pouring. The pouring superheat is 30°C, the pulling speed is 1.0m / min, and the diameter of the immersion nozzle is 45mm.

[0035] Comparative Example 5 In the continuous casting process of industrial pure iron, 0.00085% of rare earth element Ce and 0.00015% of rare earth element Sm by mass of molten iron are added to the molten iron (i.e., melt) before pouring, and the mixture is stirred evenly. Then, the slag in the molten iron is filtered out by a nanoporous ceramic filter, and then the molten iron is sent to the nozzle for pouring. The pouring superheat is 30°C, the pulling speed is 1.0m / min, and the diameter of the immersion nozzle is 45mm. Among them, ZrO2-MgO-Cr2O3-C material is used as the nozzle refractory material, and its composition and component mass percentage are: C: 35%, ZrO 2 : 45%, MgO: 3%, Cr 2 O 3 :5%.

[0036] Comparative Example 6 In the continuous casting process of industrial pure iron, 0.00085% of rare earth element Ce and 0.00015% of rare earth element Sm by mass of molten iron are added to the molten iron (i.e., melt) before pouring, and the mixture is stirred evenly. Then, the slag in the molten iron is filtered out by a nanoporous ceramic filter, and then the molten iron is sent to the nozzle for pouring. The pouring superheat is 30°C, the pulling speed is 1.0m / min, and the diameter of the immersed nozzle is 45mm. Among them, ZrO2-MgO-Cr2O3-C material is used as the nozzle refractory material, and its composition and component mass percentage are: C: 50%, ZrO 2 : 45%, MgO: 3%, Cr 2 O 3 :5%.

[0037] Effect part: The thickness of the nozzle nodule layer of the above-mentioned Examples 1 to 7 and Comparative Examples 1 to 6 after pouring was completed was measured, and the average thickness of the nozzle nodule layer of each of them is shown in Table 1.

[0038] Table 1 .

[0039] From the data of the above-mentioned Examples 1 to 7, Comparative Examples 1 to 4 and Table 1, it can be seen that: ① Compared with Example 1, Example 2 also uses a nanoporous ceramic filter to filter the slag in the molten iron, and the degree of nozzle nodule formation is reduced. It can be seen that the combined use of the two can improve the cleanliness of the molten iron and inhibit nozzle nodule formation, thereby further improving, reducing or eliminating the nozzle nodule formation problem during the pouring of industrial pure iron.

[0040] ② Compared with Example 1, Example 3 also uses ZrO 2 -MgO-Cr 2 O 3-C material is used as nozzle refractory material, and its nozzle nodule degree is reduced. It can be seen that the combined use of the two can inhibit nozzle nodule, thereby further improving, reducing or eliminating the nozzle nodule problem during industrial pure iron casting.

[0041] ③ Compared with Example 2 and Example 3, Example 4 also uses a nanoporous ceramic filter to filter the slag in the molten iron and uses ZrO 2 -MgO-Cr 2 O 3 -C material is used as nozzle refractory material, and its nozzle nodule degree is reduced. It can be seen that the coordinated use of the three can inhibit nozzle nodule, thereby further improving, reducing or eliminating the nozzle nodule problem during industrial pure iron casting.

[0042] ④ Compared with Example 1, Comparative Example 1 adopts a conventional casting process, which does not add rare earth elements Ce and Sm to the molten iron before casting, and does not use a nanoporous ceramic filter to filter the slag in the molten iron or use ZrO 2 -MgO-Cr 2 O 3 -C material is used as the nozzle refractory material, and its nozzle nodule degree is significantly higher than that of Example 1. It can be seen that the addition of rare earth elements Ce and Sm to the molten iron before pouring in Example 1 can indeed reduce the nozzle nodule caused by the aggregation of existing particles in the molten iron, reduce the adhesion and deposition process of inclusions on the inner wall of the nozzle, and make it difficult for inclusions in the continuous casting process to adhere to the nozzle surface, thereby effectively reducing or eliminating the nozzle nodule problem during the pouring of industrial pure iron.

[0043] ⑤ Compared with Example 1, the addition amounts of rare earth elements Ce and Sm in Comparative Example 2 are lower than 0.001%, and the degree of nozzle nodule formation is significantly higher than that in Example 1. It can be seen that when the total mass percentage of rare earth addition is lower than 0.001%, the impurity removal effect is poor, resulting in a weakened inhibitory effect on nozzle nodule formation.

[0044] ⑥ Compared with Example 1, the addition amount of rare earth elements Ce and Sm in Comparative Example 3 exceeds 0.003%, and the degree of nozzle nodule formation is significantly higher than that in Example 1. It can be seen that when the total mass percentage of rare earth addition exceeds 0.001%, it will be difficult to remove itself as an impurity, reduce the purity of molten iron, and lead to a weakened inhibitory effect on nozzle nodule formation.

[0045] ⑦ Compared with Example 1, the ratio of rare earth elements Ce and Sm in Comparative Example 4 is higher than 6.5, and the degree of nozzle nodule formation is significantly higher than that in Example 1. It can be seen that when the ratio of rare earth elements Ce and Sm is higher than 6.5, the synergistic impurity removal effect of the two is poor, resulting in a weakened inhibitory effect on nozzle nodule formation.

[0046] ⑧ Compared with Example 4, when the MgO content in the nozzle refractory of Comparative Example 5 is 3% (i.e. lower than 5%), the degree of nozzle nodule formation is higher than that of Example 4. It can be seen that when the MgO content in the nozzle refractory is lower than 5%, the wettability between the nozzle and molten iron is poor, and inclusions are easy to adhere, which is not conducive to inhibiting the nodule phenomenon, resulting in a weakened inhibitory effect on nozzle nodule formation.

[0047] ⑨ Compared with Example 4, when the C content in the nozzle refractory of Comparative Example 6 is 50% (i.e. greater than 40%), the degree of nozzle nodule formation is higher than that of Example 4. It can be seen that when the MgO content in the nozzle refractory is lower than 5%, decarburization reaction is likely to occur, resulting in reduced surface quality of the nozzle, which is more conducive to the adhesion of inclusions to the inner wall of the nozzle, resulting in a weakened inhibitory effect on nozzle nodule formation.

[0048] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for controlling nozzle nodules in industrial pure iron continuous casting, characterized in that: Rare earth elements Ce and Sm are added to the molten iron before pouring.

2. The method for controlling nozzle agglomeration of industrial pure iron continuous casting according to claim 1, characterized in that: Nanoporous ceramic filters are used to filter slag inclusions in molten iron.

3. A method for controlling nozzle agglomeration in industrial pure iron continuous casting according to claim 2, characterized in that: The nanoporous ceramic filter has four layers, the through holes of the first layer are 5.5 mm to 6.5 mm in diameter, the second layer are 4 mm to 5 mm in diameter, the third layer are 2.5 mm to 3.5 mm in diameter, and the fourth layer are 0.4 mm to 1.5 mm in diameter, and the through holes of each layer are staggered. The nanoporous ceramic filter is prepared as follows: ZrO2 powder, A12O3 powder and CaO powder with a particle size less than 0.2 μm are mixed in a ratio of 45% to 65% ZrO2, 20% to 30% A12O3 powder and 10% to 25% CaO powder; the raw powder is then ball-milled into nanocrystalline particles of 40nm to 90nm in a high-energy ball mill; and then a binder polyvinyl butyral and anhydrous ethanol are used to prepare a ceramic particle slurry: an organic foam polyurethane sponge is used as a porous carrier, the ceramic slurry is evenly coated on it, and after drying, the carrier material is burned out at high temperature to form a porous ceramic filter.

4. The method for controlling nozzle agglomeration of industrial pure iron continuous casting according to claim 1, characterized in that: ZrO2-MgO-Cr2O3-C material is used as the nozzle refractory, and the composition and component mass percentage of the nozzle refractory are: C: 15%~40%, ZrO2: 30%~60%, MgO: 5%~15%, Cr2O3: 1%~10%.

5. The method for controlling nozzle nodules in industrial pure iron continuous casting according to claim 2, characterized in that: ZrO2-MgO-Cr2O3-C material is used as the nozzle refractory, and the composition and component mass percentage of the nozzle refractory are: C: 15%~40%, ZrO2: 30%~60%, MgO: 5%~15%, Cr2O3: 1%~10%.

6. The method for controlling nozzle agglomeration of industrial pure iron continuous casting according to claim 3, characterized in that: ZrO2-MgO-Cr2O3-C material is used as the nozzle refractory, and the composition and component mass percentage of the nozzle refractory are: C: 15%~40%, ZrO2: 30%~60%, MgO: 5%~15%, Cr2O3: 1%~10%.

7. The method for controlling nozzle agglomeration in industrial pure iron continuous casting according to claim 1, 2, 3, 4, 5 or 6, characterized in that: The total amount of the rare earth elements Ce and Sm added is 0.001% to 0.003% of the mass of the molten iron.

8. The method for controlling nozzle agglomeration of industrial pure iron continuous casting according to claim 7, characterized in that: The mass ratio of the rare earth elements Ce and Sm is 5.5-6.5.