Continuous casting crystallizer casting powder and application thereof

Abstract

The invention provides continuous casting crystallizer casting powder and application thereof, and belongs to the technical field of steelmaking auxiliary materials. The continuous casting crystallizer casting powder is prepared from the following components in percentage by mass: 20 to 30 percent of CaO, 25 to 35 percent of Al2O3, 1 to 6 percent of MgO, 0.2 to 2 percent of Fe2O3, 1 to 5 percent of K2O, 6 to 10 percent of Na2O, 0.5 to 4 percent of F <->, 2 to 6 percent of SiO2, 7 to 15 percent of C and 0.001 to 0.003 percent of light rare earth element. Wherein the mass ratio of the CaO to the Al2O3 is 1: (0.8-1.4). The casting powder provided by the invention has a lower melting point and better adaptability and stability, and meets the production of high-carbon high-alloy rare earth heavy rail steel with the pulling speed of 0.5-1.1 m / min; and moreover, the defects of corner star cracks, longitudinal cracks, edge cracks, slag inclusion and the like on the surface of the continuous casting billet are reduced, and the product yield is increased.

Description

Technical Field

[0001] The invention relates to the technical field of steelmaking auxiliary materials, in particular to a continuous casting mold protection slag and application thereof, and in particular to a continuous casting mold protection slag for high-carbon high-alloy rare earth heavy rail steel and application thereof. Background Art

[0002] High-carbon high-alloy rare earth heavy rail steel is a symmetrical cross-section profile. Although the cross-section shape is simple, due to the large difference between the upper and lower sections and the large difference in thickness, there is serious uneven deformation during the rolling process. The R corner of the heavy rail surface is very prone to star cracks and longitudinal cracks, resulting in a yield rate of only 75.6%. When manufacturers produce this type of steel, they use existing high-carbon high-alloy protective slag and protective slag for heavy rail steel, which has a low yield rate and causes a serious problem of high production costs.

[0003] At present, the low yield rate of existing high-carbon high-alloy rare earth heavy rail steel is mainly due to the following two reasons: First, the existing high-carbon high-alloy protective slag and protective slag for heavy rail steel are generally SiO 2 -CaO-Al 2 O 3 Ternary slag system, or CaO-Al 2 O 3 Binary slag system; among them, SiO 2 -CaO-Al 2 O 3 SiO in ternary slag system 2 Reacting with rare earth oxides in the slag system, the performance of the protective slag deteriorates and the adsorption capacity is poor. The alloy elements and oxides produced by the rare earth elements in the high-carbon high-alloy rare earth heavy rail steel are adsorbed by the protective slag, which changes and deteriorates the properties of the protective slag, changes the heat transfer rate, and causes uneven shrinkage of the ingot, resulting in defects in the ingot, affecting the qualified rate. Second, in the production process of high-alloy steel, high-temperature alloy elements are easily oxidized to generate non-metallic oxides mixed in the molten steel, causing inclusions in the steel billet, destroying the original performance of the steel, resulting in defective or scrap products. 2 O 3 The binary slag system is mainly composed of a small amount of SiO 2 It is beneficial to reduce the melting point of the slag system and increase the slag adsorption of floating oxides in the molten steel. 2 O 3 , and rare earth oxides have the stability of stabilizing liquid slag, plus K 2 O、Na 2 The ability of O to lower the melting point and dilute the oxides on the surface of the molten steel will make the protective slag better adapted to the continuous casting process of high-carbon, high-alloy rare earth heavy rail steel.

[0004] For example, CN116652132A discloses a protective slag for vertical semi-continuous casting of medium-carbon high-alloy steel in ultra-large cross-section round billets, characterized in that, in terms of weight percentage, its composition includes: SiO 2 28~30%, CaO 25.5~29.5%, MgO 1~2.5%, Al 2 O 3 7~10%, MnO 0~0.5%, (Na 2 O+K 2 O)1.5~4.5%, F 1~2.5%, Fe 2 O 3 2~4%, C21~25%, and the remainder is inevitable impurities. The mold slag of this formula can solve the problems of liquid surface insulation and slag consumption control during the long-term static solidification stage of semi-continuous casting of ultra-large section round billets with high carbon and high alloy steel to a certain extent, but it is limited in controlling the adaptability and stability of the mold slag and reducing the surface cracks of the continuous casting billet.

[0005] For example, CN111440923A discloses a protective slag for high-carbon high-alloy wear-resistant steel and a preparation method thereof, wherein the protective slag comprises a basic slag, a solvent and a melting rate regulator; wherein the basic slag comprises 27.6-33.6% CaO and 27.6-33.6% SiO 2 29.2~35.2%; the composition of the co-solvent includes Al 2 O 3 3.8~6.6%, F 3.8~9% and Na 2 O 6.6-9.2wt%; the melting rate regulator includes C11.7-14.3%. Similarly, the mold slag also has a serious problem of low yield rate causing high production costs.

[0006] Therefore, it is urgent to design a new type of protective slag to reduce the problems of R corner star cracks and longitudinal cracks that have always existed in the continuous casting process of heavy rail steel and improve the yield rate.

[0007] In view of this, the present invention is proposed. Summary of the invention

[0008] One of the purposes of the present invention is to provide a continuous casting mold protection slag which can reduce the problems of R corner star cracking and longitudinal cracking which always exist in the continuous casting process of heavy rail steel and further improve the yield rate of high carbon high alloy rare earth heavy rail steel.

[0009] The second object of the present invention is to provide an application of the continuous casting mold powder in the production of high-carbon high-alloy rare earth heavy rail steel. In particular, the continuous casting mold powder is used in the continuous casting production of high-alloy rare earth heavy rail steel at a casting speed of 0.5 to 1.1 m / min.

[0010] To achieve the above object of the present invention, the following technical solutions are specifically adopted:

[0011] In a first aspect, the present invention provides a continuous casting mold powder, and the continuous casting mold powder comprises the following components by mass percentage:

[0012] CaO 20-30%, Al 2 O 3 25-35%, MgO 1-6%, Fe 2 O 3 0.2-2%, K 2 O 1-5%, Na 2 O 6-10%, F - 0.5-4%, SiO 2 2-6%, C 7-15%, light rare earth elements 0.001-0.003%.

[0013] In a preferred embodiment, the continuous casting mold powder consists of the following components by mass percentage:

[0014] CaO 20-30%, Al 2 O 3 25-35%, MgO 1-6%, Fe 2 O 3 0.2-2%, K 2 O 1-5%, Na 2 O 6-10%, F-0.5-4%, SiO 2 2-6%, C 7-15%, light rare earth elements 0.001-0.003%, and the balance is volatile components and / or inevitable impurities.

[0015] In a preferred embodiment, the continuous casting mold powder consists of the following components by mass percentage:

[0016] CaO 22-30%, Al 2 O 3 25-35%, MgO 1-3%, Fe 2 O 3 0.2-2%, K 2 O 1-5%, Na 2 O 6-10%, F - 0.5-4%, SiO 2 2-6%, C 8-13%, light rare earth elements 0.001-0.003%, and the balance is volatile components and / or inevitable impurities.

[0017] In a preferred embodiment, the CaO and Al2 O 3 The mass ratio of O is 1:(0.8 - 1.4).

[0018] In a preferred embodiment, the raw materials for preparing the continuous casting mold powder include potassium feldspar powder, low-silicon pre-melted material, corundum powder, white alkali, calcite, light rare earth ore powder, carbon black, graphite, cryolite, magnesia, and binder.

[0019] In a preferred embodiment, the raw materials for preparing the continuous casting mold powder include the following components by weight:

[0020] 3 - 15 parts of potassium feldspar powder, 35 - 60 parts of low-silicon pre-melted material, 3 - 15 parts of corundum powder, 7 - 12 parts of white alkali, 1 - 10 parts of calcite, 3 - 6 parts of light rare earth ore powder, 1 - 3 parts of carbon black, 6.5 - 14 parts of graphite, 2.5 - 7 parts of cryolite, 1 - 4 parts of magnesia, and 0.8 - 2 parts of binder.

[0021] In a preferred embodiment, the raw materials for preparing the continuous casting mold powder include the following components by mass percentage:

[0022] 3 - 15% of potassium feldspar powder, 35 - 60% of low-silicon pre-melted material, 3 - 15% of corundum powder, 7 - 12% of white alkali, 1 - 12% of calcite, 3 - 6% of light rare earth ore powder, 1 - 3% of carbon black, 6.5 - 14% of graphite, 2.5 - 7% of cryolite, 1 - 4% of magnesia, and 0.8 - 3% of binder.

[0023] In a preferred embodiment, the mass ratio of CaO and Al 2 O 3 in the low-silicon pre-melted material is 1:(0.7 - 0.9), preferably 1:0.8; and the content of SiO 2 in the low-silicon pre-melted material is less than 6% of the total mass of the low-silicon pre-melted material, preferably 2 - 6%.

[0024] In a preferred embodiment, the content of Al 2 O 3 in the corundum powder accounts for more than 99% of the total mass of the corundum powder.

[0025] In a preferred embodiment, the light rare earth ore powder is selected from any one or a combination of at least two of light rare earth ore powders of lanthanum element, cerium element, praseodymium element, neodymium element, promethium element, samarium element, or europium element.

[0026] In a preferred embodiment, the carbon content in the carbon black is greater than 98%, the oil absorption value is greater than 100 g / cm 3 , and the iodine absorption value is greater than 130 g / kg.

[0027] In a preferred embodiment, the carbon content of the graphite is greater than 90%, and the oil absorption value is greater than 70g / cm 3 , iodine absorption value is greater than 80g / kg.

[0028] In a preferred embodiment, the binder is selected from any one of carboxymethyl cellulose, starch or dextrin, or a combination of at least two thereof.

[0029] In a preferred embodiment, the melting point of the continuous casting mold protection slag is 850-980°C; the viscosity of the continuous casting mold protection slag is 0.2-0.45 Pa·s at 1300°C; and the crystallization rate of the continuous casting mold protection slag is 0-10%.

[0030] In a second aspect, the present invention provides an application of the continuous casting mold protection slag described in the first aspect, and the application of the continuous casting mold protection slag in the production of high-carbon high-alloy rare earth heavy rail steel.

[0031] In a preferred embodiment, the continuous casting mold protection slag is used in the continuous casting production of high-alloy rare earth heavy rail steel at a casting speed of 0.5 to 1.1 m / min.

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] (1) The present invention uses low silicon pre-melted material as the base material and strictly controls the CaO and Al 2 O 3 The ratio of 20% to 10% ensures that the protective slag has a lower melting point. At the same time, light rare earth element powder is added to the protective slag to improve the adaptability and stability of the protective slag.

[0034] (2) The mold slag of the present invention contains an appropriate amount of K 2 O、Na 2 O, and control the F- content, reduce the melting point and viscosity and avoid the generation of gunite. The appropriate amount of light rare earth ore powder and flux effectively dilute and digest the slag denaturation, which can ensure good lubrication and heat transfer effect and effectively improve the smoothness of the continuous casting process;

[0035] (3) The mold slag of the present invention can improve the quality of the casting, reduce defects such as star cracks, longitudinal cracks, edge cracks, slag inclusions, etc. on the surface of the continuous casting billet, improve the product yield, reduce the grinding of the continuous casting billet, reduce the scrap volume, and reduce the production cost;

[0036] (4) The protective slag of the present invention effectively improves the product yield rate, and increases the one-time yield rate to 98.3%; and further increases the pouring speed, that is, the pouring speed is increased from 0.5-0.7m / min to 0.9-1.1m / min, and the application range of the protective slag is wider. DETAILED DESCRIPTION

[0037] Unless otherwise defined herein, scientific and technical terms used in connection with the present invention shall have the meanings commonly understood by one of ordinary skill in the art. The meanings and scopes of the terms shall be clear. However, in any case of potential ambiguity, the definitions provided herein shall prevail over any dictionary or extrinsic definition. In this application, unless otherwise specified, the use of "or" means "and / or". In addition, the use of the term "comprising" and other forms is non-restrictive.

[0038] The continuous casting mold powder provided by this application and its application will be specifically described below.

[0039] The present invention provides a continuous casting mold powder, and the continuous casting mold powder comprises the following components by mass percentage:

[0040] CaO 20-30%, Al 2 O 3 25-35%, MgO 1-6%, Fe 2 O 3 0.2-2%, K 2 O 1-5%, Na 2 O 6-10%, F-0.5-4%, SiO 2 2-6%, C 7-15%, light rare earth elements 0.001-0.003%.

[0041] Based on the total weight of the components in the continuous casting mold powder being 100%, the content of CaO is 20-30%, for example, it can be 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, etc.

[0042] Based on the total weight of the components in the continuous casting mold powder being 100%, the content of Al 2 O 3 is 25-35%, for example, it can be 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32%, 33%, 34%, 35%, etc.

[0043] In the continuous casting mold powder of the present invention, the mass ratio of CaO to Al 2 O 3 is 1:(0.8-1.4), for example, it can be 1:0.8, 1:0.9, 1:1, 1:1.1, 1:1.2, 1:1.3, 1:1.4, etc.

[0044] It should be noted that the present invention strictly controls the CaO and Al in the powder 2 O 3The mass ratio of SiO2 is 1:(0.8~1.4); it can make the protective slag have the lowest melting point, so that the protective slag has the characteristics of refining slag, can effectively absorb non-metallic oxides in molten steel, ensure the purity of molten steel, and solve the influence of non-metallic impurities on the quality of steel billets. 2 -CaO-Al 2 O 3 The slag system has a weak ability to absorb non-metallic inclusions and cannot effectively remove oxides produced by high temperature of the alloy, causing inclusions in the ingot. Therefore, the continuous casting crystallizer protection slag provided by the present invention successfully solves the inclusion problem of high-carbon, high-alloy rare earth heavy rail steel, that is, solves the problem of low yield rate.

[0045] Taking the weight of each component in the continuous casting crystallizer protection slag as 100%, the content of MgO is 1-6%, for example, it can be 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 5.5%, 6% and the like.

[0046] Based on the weight of each component in the continuous casting mold protection slag being 100%, the Fe 2 O 3 The content of is 0.2-2%, for example, it can be 0.2%, 0.4%, 0.6%, 0.8%, 1%, 1.2%, 1.4%, 1.6%, 1.8%, 2% and the like.

[0047] Based on the weight of each component in the continuous casting mold protection slag being 100%, the K 2 The content of O is 0.2% to 2%, for example, it can be 0.2%, 0.4%, 0.6%, 0.8%, 1%, 1.2%, 1.4%, 1.6%, 1.8%, 2%, etc.

[0048] Based on the weight of each component in the continuous casting mold protection slag as 100%, the Na 2 The content of O is 6% to 10%, for example, 6%, 6.5%, 7%, 7.5%, 8%, 8.5%, 9%, 9.5%, 10%, etc.

[0049] Based on the weight of each component in the continuous casting crystallizer protection slag as 100%, the F- content is 0.5-4%, for example, it can be 0.5%, 0.6%, 0.8%, 1%, 1.2%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, etc.

[0050] Based on the weight of each component in the continuous casting mold protection slag being 100%, the SiO 2 The content of is 2-6%, for example, it can be 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 5.5%, 6% and the like.

[0051] Based on the total weight of each component in the continuous casting mold powder being 100%, the content of C is 7-15%, for example, it can be 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, etc.

[0052] It should be noted that in the continuous casting mold powder, controlling the C content within 7-15% is mainly because when the C content is lower than 7%, the heat preservation effect of the powder and its ability to control the melting rate decrease, and problems such as cold steel bonding may occur during use, affecting the smooth progress of the process and the quality of the cast slab; when it is higher than 15%, the powder is not suitable for granulation during production, the product recovery rate is low, and it is not easy to melt during use, resulting in insufficient liquid slag to lubricate the cast slab and prone to sticking accidents.

[0053] Based on the total weight of each component in the continuous casting mold powder being 100%, the content of light rare earth elements is 0.001-0.003%, for example, it can be 0.001%, 0.0012%, 0.0014%, 0.0016%, 0.0018%, 0.002%, 0.0022%, 0.0024%, 0.0026%, 0.0028%, 0.003%, etc.

[0054] Furthermore, in the continuous casting mold powder, control the content of Na 2 O to be 6-10%, and Na 2 O has the function of reducing the melting point and viscosity at the same time; control the content of K 2 O to be 1-5%, and K 2 O has the function of reducing the melting point; control the content of F- to be 0.5-4% to avoid the formation of cuspidine. And the total amount of Na 2 O, K 2 O, F- and light rare earth elements controlled within the range of 10-15% can keep the molten slag at a lower melting temperature and viscosity, which is beneficial to absorbing the high melting point oxides formed by alloying elements in this steel grade, making use of the characteristics of eutectics formed by low melting point oxides and high melting point oxides in the molten slag state in the molten slag theory.

[0055] Among them, rare earth elements refer to any one or at least two combinations of lanthanum, cerium, praseodymium, neodymium, promethium, samarium, and europium elements.

[0056] In a preferred embodiment, the continuous casting mold powder is composed of the following components by mass percentage:

[0057] CaO 20-30%, Al 2 O 3 25-35%, MgO 1-6%, Fe 2 O 3 0.2-2%, K2 O 1 - 5%, Na 2 O 6 - 10%, F - 0.5 - 4%, SiO 2 2 - 6%, C 7 - 15%, light rare earth elements 0.001 - 0.003%, the balance being volatile matter and / or inevitable impurities.

[0058] In a preferred embodiment, the continuous casting mold powder consists of the following components by mass percentage:

[0059] CaO 22 - 30%, Al 2 O 3 25 - 35%, MgO 1 - 3%, Fe 2 O 3 0.2 - 2%, K 2 O 1 - 5%, Na 2 O 6 - 10%, F - 0.5 - 4%, SiO 2 2 - 6%, C 8 - 13%, light rare earth elements 0.001 - 0.003%, the balance being volatile matter and / or inevitable impurities.

[0060] In a preferred embodiment, the raw materials for preparing the continuous casting mold powder include potassium feldspar powder, low - silicon premelted material, corundum powder, soda ash, calcite, light rare earth ore powder, carbon black, graphite, cryolite, magnesia, and binder.

[0061] In a preferred embodiment, the raw materials for preparing the continuous casting mold powder consist of the following components by weight parts:

[0062] Potassium feldspar powder 3 - 15 parts, low - silicon premelted material 35 - 60 parts, corundum powder 3 - 15 parts, soda ash 7 - 12 parts, calcite 1 - 10 parts, light rare earth ore powder 3 - 6 parts, carbon black 1 - 3 parts, graphite 6.5 - 14 parts, cryolite 2.5 - 7 parts, magnesia 1 - 4 parts, binder 0.8 - 2 parts.

[0063] In a preferred embodiment, the raw materials for preparing the continuous casting mold powder consist of the following components by mass percentage:

[0064] Potassium feldspar powder 3 - 15%, low - silicon premelted material 35 - 60%, corundum powder 3 - 15%, soda ash 7 - 12%, calcite 1 - 12%, light rare earth ore powder 3 - 6%, carbon black 1 - 3%, graphite 6.5 - 14%, cryolite 2.5 - 7%, magnesia 1 - 4%, binder 0.8 - 3%.

[0065] Based on the total mass of the raw materials for preparing the continuous casting mold powder being 100%, the addition amount of potassium feldspar powder is 3 - 15%, for example, it can be 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, etc.

[0066] Based on the total mass of the raw materials for preparing the continuous casting mold powder being 100%, the addition amount of low - silicon pre - fused material is 35 - 60%, for example, it can be 35%, 36%, 38%, 40%, 42%, 45%, 50%, 52%, 55%, 58%, 60%, etc.

[0067] Based on the total mass of the raw materials for preparing the continuous casting mold powder being 100%, the addition amount of corundum powder is 3 - 15%, for example, it can be 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, etc.

[0068] Based on the total mass of the raw materials for preparing the continuous casting mold powder being 100%, the addition amount of white alkali is 7 - 12%, for example, it can be 7%, 7.5%, 8%, 8.5%, 9%, 9.5%, 10%, 10.5%, 11%, 11.5%, 12%, etc.

[0069] Based on the total mass of the raw materials for preparing the continuous casting mold powder being 100%, the addition amount of calcite is 1 - 12%, for example, it can be 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, etc.

[0070] Based on the total mass of the raw materials for preparing the continuous casting mold powder being 100%, the addition amount of light rare - earth ore powder is 3 - 6%, for example, it can be 3%, 3.5%, 4%, 4.5%, 5%, 5.5%, 6%, etc.

[0071] It should be noted that in the raw materials for preparing the continuous casting mold powder of the present invention, 3 - 6% of light rare - earth ore powder is added. The purpose is to reduce the modification of the mold powder and can solidify the properties of the mold powder in advance, reducing the influence of absorbing rare - earth oxides in the molten steel on the properties of the mold powder, so as to better ensure the stability of the heat flux. When the addition amount of light rare - earth ore powder is greater than 6%, it will not only increase the material cost but also increase the melting temperature of the mold powder product; when the addition amount of light rare - earth ore powder is less than 3%, it does not have the property of solidifying the mold powder.

[0072] Based on the total mass of the raw materials for preparing the continuous casting mold powder being 100%, the addition amount of carbon black is 1 - 3%, for example, it can be 1%, 1.2%, 1.4%, 1.6%, 1.8%, 2%, 2.2%, 2.4%, 2.6%, 2.8%, 3%, etc.

[0073] Based on the total mass of the raw materials for preparing the continuous casting mold powder being 100%, the addition amount of graphite is 6.5 - 14%, for example, it can be 6.5%, 7%, 7.5%, 8%, 8.5%, 9%, 9.5%, 10%, 10.5%, 11%, 11.5%, 12%, 12.5%, 13%, 13.5%, 14%, etc.

[0074] Based on the total mass of the raw materials for preparing the continuous casting mold powder being 100%, the addition amount of cryolite is 2.5 - 7%, for example, it can be 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 5.5%, 6%, 6.5%, 7%, etc.

[0075] Based on the total mass of the raw materials for preparing the continuous casting mold powder being 100%, the addition amount of magnesia is 1 - 4%, for example, it can be 1%, 1.2%, 1.5%, 1.8%, 2%, 2.2%, 2.5%, 2.8%, 3%, 3.2%, 3.5%, 3.8%, 4%, etc.

[0076] Based on the total mass of the raw materials for preparing the continuous casting mold powder being 100%, the addition amount of binder is 0.8 - 3%, for example, it can be 0.8%, 0.9%, 1%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2%, 3%, etc.

[0077] In a preferred embodiment, the mass ratio of CaO to Al 2 O 3 in the low - silicon premelted material is 1:(0.7 - 0.9), for example, it can be 1:0.7, 1:0.72, 1:0.74, 1:0.76, 1:0.78, 1:0.8, 1:0.82, 1:0.84, 1:0.86, 1:0.88, 1:0.9, etc., and preferably 1:0.8;

[0078] In a preferred embodiment, the mass percentage content of SiO 2 in the low - silicon premelted material is ≤6%, for example, it can be 6%, 5.5%, 5%, 4.5%, 4%, 3.5%, 3%, 2.5%, 2%, 1.5%, 1%, etc., and preferably 2 - 6%.

[0079] It should be noted that the low - silicon premelted material added to the raw materials for preparing the continuous casting mold powder in the present invention has been pre - melted at high temperature in advance, with stable composition and not prone to fractional melting. Adding the low - silicon premelted material to the raw materials for preparing the continuous casting mold powder in the present invention aims to control the ratio of CaO to Al 2 O 3The proportion is to ensure that the mold powder has the lowest melting point, and the melting point of the mold powder increases when it is lower or higher than this proportion.

[0080] In a preferred embodiment, the alumina powder contains Al 2 O 3 in an amount of more than 99% of the total mass of the alumina powder. For example, it can be 99%, 99.2%, 99.4%, 99.6%, 99.8%, etc. That is, the alumina powder is white alumina powder with an Al 2 O 3 content greater than 99%.

[0081] In a preferred embodiment, the light rare earth ore powder is selected from any one or a combination of at least two of the light rare earth ore powders of lanthanum element, cerium element, praseodymium element, neodymium element, promethium element, samarium element or europium element.

[0082] In a preferred embodiment, the carbon content in the carbon black is greater than 98%, for example, it can be 98%, 98.2%, 98.4%, 98.6%, 98.8%, etc., and the oil absorption value is greater than 100 g / cm 3 , for example, it can be 100 g / cm 3 , 105 g / cm 3 , 110 g / cm 3 , 115 g / cm 3 , 120 g / cm 3 , 125 g / cm 3 , 130 g / cm 3 , 135 g / cm 3 , 140 g / cm 3 etc., and the iodine absorption value is greater than 130 g / kg, for example, it can be 130 g / kg, 135 g / kg, 140 g / kg, 145 g / kg, 150 g / kg, etc.

[0083] In a preferred embodiment, the carbon content in the graphite is greater than 90%, for example, it can be 90%, 90.2%, 90.4%, 90.6%, 90.8%, 91%, 92%, 94%, 95%, etc., and the oil absorption value is greater than 70 g / cm 3 , for example, it can be 70 g / cm 3 , 72 g / cm 3 , 74 g / cm 3 , 76 g / cm 3 , 78 g / cm 3 , 80 g / cm 3 etc., and the iodine absorption value is greater than 80 g / kg, for example, it can be 80 g / cm 3 , 82 g / cm 3 , 84 g / cm 3 , 86 g / cm3 , 88 g / cm 3 , 90 g / cm 3 etc.

[0084] In a preferred embodiment, the binder is selected from any one or a combination of at least two of carboxymethyl cellulose, starch or dextrin.

[0085] In a preferred embodiment, the melting point of the continuous casting mold powder is 850 - 980 °C, for example, it can be 850 °C, 860 °C, 870 °C, 880 °C, 900 °C, 920 °C, 940 °C, 960 °C, 980 °C, etc.

[0086] In a preferred embodiment, the viscosity of the continuous casting mold powder at 1300 °C is 0.2 - 0.45 Pa·s, for example, it can be 0.2 Pa·s, 0.25 Pa·s, 0.3 Pa·s, 0.35 Pa·s, 0.4 Pa·s, 0.45 Pa·s, etc.

[0087] It should be noted that below the above - defined range, the surface tension of the liquid slag becomes larger, the viscosity increases, the liquid slag layer becomes thicker, and the slag consumption becomes smaller, which is not conducive to the flow of the molten slag and lubrication; above the above - defined range, the surface tension of the liquid slag becomes smaller, the fluidity of the liquid slag is too strong, the liquid slag filling between the billet shell and the inner wall of the mold is uneven, the formed billet is uneven, and cracks are likely to occur.

[0088] In a preferred embodiment, the crystallization rate of the continuous casting mold powder is 0 - 10%, for example, it can be 0%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, etc.

[0089] In the present invention, the preparation method of the continuous casting mold powder is an optionally selected preparation method of mold powder products in the art. For example, it can be: adding the binder into a mixing tank filled with water according to the ratio, adding potassium feldspar powder, low - silicon pre - fused material, corundum powder, white alkali, calcite, light rare - earth ore powder, carbon black, graphite, cryolite and magnesia, making pulp and mixing evenly to obtain a slurry. Pumping the slurry into a high - temperature tower for spray granulation, and then screening with a mesh to obtain the continuous casting mold powder.

[0090] In a second aspect, the present invention provides an application of the continuous casting mold powder described in the first aspect, and the application of the continuous casting mold powder in the production of high - carbon high - alloy rare - earth heavy rail steel.

[0091] In a preferred embodiment, the continuous casting mold powder is used in the continuous casting production of high-alloy rare earth heavy rail steel with a drawing speed of 0.5 - 1.1 m / min (for example, it can be 0.5 m / min, 0.6 m / min, 0.7 m / min, 0.8 m / min, 0.9 m / min, 1.0 m / min, 1.1 m / min, etc.).

[0092] The technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of them. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative work fall within the scope of protection of the present invention.

[0093] The present invention will be further described below through embodiments. Unless otherwise specified, the materials in the embodiments are prepared according to existing methods or directly purchased from the market.

[0094] Example 1

[0095] This example provides a continuous casting mold powder, and the continuous casting mold powder includes the following components by weight:

[0096] 3.5 parts by weight of potassium feldspar powder, 36 parts by weight of low-silicon premelt, 9 parts by weight of white corundum powder, 10 parts by weight of calcite powder, 8 parts by weight of white soda ash, 3 parts by weight of light rare earth ore powder, 2 parts by weight of carbon black, 11 parts by weight of graphite, 6.5 parts by weight of cryolite, 3 parts by weight of magnesia, and 2 parts by weight of carboxymethyl cellulose.

[0097] Among them, the mass ratio of CaO to Al 2 O 3 in the low-silicon premelt is 1:0.8, and the SiO 2 content in the low-silicon premelt is 5.3 wt%; the Al 2 O 3 content in the white corundum powder is 99.4 wt%; the carbon content in the carbon black is 98.2 wt%, the oil absorption value is 127 g / cm 3 , and the iodine absorption value is 142 g / kg; the carbon content in the graphite is 90.2 wt%, the oil absorption value is 72 g / cm 3 , and the iodine absorption value is 82 g / kg.

[0098] This continuous casting mold powder is composed of the following components by mass percentage:

[0099] CaO 26.3%, Al 2 O 3 34.93%, SiO 2 5.47%, MgO 2.41%, Fe2 O 3 0.43%, K 2 O 2.3%, Na 2 O 7.81%, F - 3.21%, C 12.12%, light rare earth elements 0.001%, and the balance is volatile matter and unavoidable impurities.

[0100] Among them, the light rare earth elements include lanthanum, cerium, praseodymium, neodymium, promethium, samarium, and europium.

[0101] The melting temperature of the continuous casting mold powder is 863 °C, and the viscosity at 1300 °C is 0.26 Pa·s, and the crystallization rate is 3%.

[0102] The obtained mold powder was tested in a domestic factory. The test slag model is XLG-10, the test steel grade is 75V, and the section is 280×380 mm 2 , and the drawing speed is 0.7 - 0.9 m / min. A total of 3T of mold powder was tested. During the test, the spreading and fluidity of this type of mold powder in the mold were good, and the mold liquid level was stable.

[0103] When the total slag layer is controlled at 45 - 65 mm, the thickness of the liquid slag layer is 8 - 11 mm, the slag layer structure is obvious, the thickness of the liquid slag layer is appropriate, the size of the flame on the mold liquid level is appropriate, the average slag consumption is 0.48 - 0.53 kg / T, the generation rate of slag bars in the mold is slow, the surface of the cast billet produced by the test has no defects, and the later rolling steel detection data shows that there are no crack and slag inclusion defects in the cast billet, achieving good results.

[0104] Example 2

[0105] This example provides a continuous casting mold powder, and the continuous casting mold powder includes the following components by weight:

[0106] 6 parts by weight of potassium feldspar powder, 2.5 parts by weight of cryolite, 10 parts by weight of soda ash, 13.4 parts by weight of white corundum powder, 2 parts by weight of carbon black, 12.1 parts by weight of graphite, 4 parts by weight of light rare earth ore powder, 43 parts by weight of low-silicon premelting material, 3 parts by weight of calcite powder, 2 parts by weight of magnesia, 2 parts by weight of starch.

[0107] Among them, the mass ratio of CaO to Al 2 O 3 in the low-silicon premelting material is 1:0.8, and the SiO 2 content in the low-silicon premelting material is 5.5 wt%; the Al 2 O 3 content in the white corundum powder is 99.3 wt%; the carbon content of the carbon black is 98.2 wt%, and the oil absorption value is 127 g / cm3 , the iodine absorption value is 142 g / kg; the carbon content of the graphite is 90.2 wt%, and the oil absorption value is 72 g / cm 3 , and the iodine absorption value is 82 g / kg.

[0108] The continuous casting mold powder consists of the following components by mass percentage:

[0109] CaO 25.1%, Al 2 O 3 34.3%, SiO 2 4.37%, MgO 1.52%, Fe 2 O 3 0.41%, K 2 O 3.4%, Na 2 O 8.73%, F - 2.79%, C 9.4%, light rare earth elements 0.0016%, and the balance is volatile matter and unavoidable impurities.

[0110] Among them, the light rare earth elements include lanthanum element, cerium element, praseodymium element, neodymium element, promethium element, samarium element and europium element.

[0111] The melting temperature of the continuous casting mold powder is 923 °C, and the viscosity at 1300 °C is 0.32 Pa·s, and the crystallization rate is 6%.

[0112] The obtained mold powder was tested in a domestic factory. The test slag model is XLG-11, the test steel grade is 75V, and the section is 280×380 mm 2 , and the casting speed is 0.7 - 1.1 m / min. A total of 5 T of mold powder was tested. During the test, the spreading property and fluidity of this type of mold powder in the mold were good, and the mold liquid level was stable.

[0113] When the total slag layer is controlled at 45 - 65 mm, the thickness of the liquid slag layer is 8 - 11 mm, the slag layer structure is obvious, the thickness of the liquid slag layer is appropriate, the size of the flame on the mold liquid level is appropriate, the average slag consumption is 0.45 - 0.51 kg / T, the generation speed of slag bars in the mold is slow, the surface of the cast slab produced by the test has no defects, and the test data of subsequent rolling shows that there are no crack and slag inclusion defects in the cast slab, achieving good results.

[0114] Example 3

[0115] This example provides a continuous casting mold powder, and the continuous casting mold powder includes the following components by weight:

[0116] 11.5 parts by weight of potassium feldspar powder, 3 parts by weight of cryolite, 7 parts by weight of soda ash, 6 parts by weight of white fused alumina powder, 1.5 parts by weight of carbon black, 7.5 parts by weight of graphite, 5 parts by weight of light rare earth ore powder, 55 parts by weight of low-silica premelt, 2.5 parts by weight of magnesia, 1 part by weight of dextrin.

[0117] Among them, the mass ratio of CaO to Al 2 O 3 in the low-silica premelt is 1:0.8, and the SiO 2 content in the low-silica premelt is 5.3 wt%; the Al 2 O 3 content in the white fused alumina powder is 99.4 wt%; the carbon content of the carbon black is 98.2 wt%, the oil absorption value is 127 g / cm 3 , and the iodine absorption value is 142 g / kg; the carbon content of the graphite is 90.2 wt%, the oil absorption value is 72 g / cm 3 , and the iodine absorption value is 82 g / kg.

[0118] The continuous casting mold powder is composed of the following components by mass percentage:

[0119] CaO 29.41%, Al 2 O 3 33.36%, SiO 2 5.47%, MgO 1.81%, Fe 2 O 3 0.83%, K 2 O 4.1%, Na 2 O 6.11%, F - 2.2%, C 8.16%, light rare earth elements 0.0019%, and the balance is volatile matter and unavoidable impurities.

[0120] Among them, the light rare earth elements include lanthanum element, cerium element, praseodymium element, neodymium element, promethium element, samarium element and europium element.

[0121] The melting temperature of the continuous casting mold powder is 965 °C, and the viscosity at 1300 °C is 0.41 Pa·s, and the crystallization rate is 9%.

[0122] The obtained mold powder was tested in a domestic factory. The test slag model is XLG-12, the test steel grade is 75V, the cross-section is 280×380 mm 2 , and the drawing speed is 0.5 - 0.9 m / min. A total of 3 T of mold powder was tested.

[0123] During the test, the mold powder of this type had good spreading and fluidity in the mold, and the mold liquid level was stable. When the total slag layer was controlled at 45 - 65 mm, the thickness of the liquid slag layer was 10 - 13 mm, the slag layer structure was obvious, the thickness of the liquid slag layer was appropriate, the size of the flame on the mold liquid level was appropriate, the average slag consumption was 0.42 - 0.48 kg / T, the generation rate of slag bars in the mold was slow, the surface of the continuously cast billets produced by the test had no defects, and the later rolling inspection data showed that there were no crack and slag inclusion defects in the billets, achieving good results.

[0124] Comparative Example 1

[0125] This comparative example provides a continuous casting mold powder, and the continuous casting mold powder includes the following components by weight:

[0126] 2 parts by weight of potassium feldspar powder, 3 parts by weight of cryolite, 8 parts by weight of soda ash, 3 parts by weight of white corundum powder, 1.5 parts by weight of carbon black, 10.5 parts by weight of graphite, 2 parts by weight of light rare earth ore powder, 55 parts by weight of low-silicon pre-melted material, 10 parts by weight of calcite powder, 3 parts by weight of magnesia, 2 parts by weight of carboxymethyl cellulose.

[0127] Among them, the mass ratio of CaO to Al 2 O 3 in the low-silicon pre-melted material is 1:0.8, and the SiO 2 content in the low-silicon pre-melted material is 8.6 wt%; the Al 2 O 3 content in the white corundum powder is 99.4 wt%; the carbon content of the carbon black is 98.2 wt%, the oil absorption value is 127 g / cm 3 , and the iodine absorption value is 142 g / kg; the carbon content of the graphite is 90.2 wt%, the oil absorption value is 72 g / cm 3 , and the iodine absorption value is 82 g / kg.

[0128] This continuous casting mold powder is composed of the following components by mass percentage:

[0129] CaO 34.8%, Al 2 O 3 25.35%, SiO 2 3.57%, MgO 6.81%, Fe 2 O 3 0.43%, K 2 O 0.50%, Na 2 O 6.76%, F - 2.71%, C 10.3%, light rare earth elements 0.0006%, and the balance is volatile matter and unavoidable impurities.

[0130] Among them, the light rare earth elements include lanthanum, cerium, praseodymium, neodymium, promethium, samarium and europium.

[0131] The melting temperature of the continuous casting mold powder is 1006 °C, the viscosity at 1300 °C is 0.5 Pa·s, and the crystallization rate is 15%.

[0132] The obtained mold powder was tested in a domestic factory. The test slag model is XLG-13, the test steel grade is 75MnV, and the section is 280×380 mm 2 , and the drawing speed is 0.7 - 1.0 m / min. A total of 2 T of mold powder was tested. During the test, the spreading and fluidity of this type of mold powder in the mold were good, and the mold liquid level was stable.

[0133] When the total slag layer is controlled at 40 - 60 mm, the thickness of the liquid slag layer is 18 mm, the consumption is 0.25 kg / T, the thickness of the liquid slag layer is too thick, the consumption is too low, the performance of the mold powder is unstable, the generation speed of slag bars in the mold is too fast, there are 6 sticking alarms during the test production process, there are sticking marks on the surface of the cast billet produced, there are tooth-shaped missing blocks at the corners of the cast billet, and the cutting scrap length is 11 meters. There are transverse cracks at the R corner of the rolled finished product rail beam, and the crack rate is 1.18%, which cannot meet the production requirements.

[0134] Comparative Example 2

[0135] This comparative example provides a continuous casting mold powder, which includes the following components by weight:

[0136] 15 parts by weight of potassium feldspar powder, 6.5 parts by weight of cryolite, 5 parts by weight of white soda, 1.50 parts by weight of carbon black, 13 parts by weight of graphite, 1 part by weight of light rare earth ore powder, 44 parts by weight of low-silicon pre-melted material, 8 parts by weight of calcite powder, 4 parts by weight of magnesia, 2 parts by weight of carboxymethyl cellulose.

[0137] Among them, the mass ratio of CaO to Al 2 O 3 in the low-silicon pre-melted material is 1:0.8, and the SiO 2 content in the low-silicon pre-melted material is 7.8 wt%; the Al 2 O 3 content in white corundum powder is 99.4 wt%; the carbon content of carbon black is 98.2 wt%, the oil absorption value is 127 g / cm 3 , and the iodine absorption value is 142 g / kg; the carbon content of graphite is 90.2 wt%, the oil absorption value is 72 g / cm 3 , and the iodine absorption value is 82 g / kg.

[0138] The continuous casting mold powder is composed of the following components by mass percentage:

[0139] CaO 32.03%, Al 2 O 3 24.56%, SiO 2 7.65%, MgO 3.88%, Fe 2 O 3 0.49%, K 2 O 4.3%, Na 2 O 5.23%, F - 4.79%, C 10.42%, light rare earth elements 0.0002%, and the balance is volatile matter and unavoidable impurities.

[0140] Among them, the light rare earth elements include lanthanum, cerium, praseodymium, neodymium, promethium, samarium and europium.

[0141] The melting temperature of the continuous casting mold powder is 1077 °C, the viscosity at 1300 °C is 0.09 Pa·s, and the crystallization rate is 11%.

[0142] The obtained mold powder was tested in a domestic factory. The test slag model is XLG-14, the test steel grade is 75V, and the section is 280×380 mm 2 , and the drawing speed is 0.7 - 0.9 m / min. A total of 3T of mold powder was tested. During the test, the thickness of the liquid slag layer of this type of mold powder during use in the mold was 6 mm, the consumption was 0.28 kg / T, the liquid slag layer was too thin, the consumption was too low, the performance of the mold powder was unstable, it could not be fully supplied and filled between the billet shell and the mold, the lubrication and heat transfer effects could not be guaranteed, the drawing speed of the steel mill could not be increased, which was extremely unfavorable for smooth production. The longitudinal cracks on the surface of the cast billets produced by the test were obvious, the crack rate was 8.51%, and the star crack rate at the R corner of the rolled rail beam was 3.31% and the longitudinal crack rate was 9.1%, which could not meet the production requirements.

[0143] Comparative Example 3

[0144] This comparative example provides a continuous casting mold powder, and the continuous casting mold powder includes the following components by weight:

[0145] 9.5 parts by weight of potassium feldspar powder, 30 parts by weight of low-silicon pre-melted material, 15 parts by weight of white corundum powder, 8 parts by weight of calcite powder, 8 parts by weight of white soda ash, 2 parts by weight of carbon black, 12 parts by weight of graphite, 6.5 parts by weight of cryolite, 4 parts by weight of magnesia, 2 parts by weight of carboxymethyl cellulose.

[0146] The light rare earth ore powder was not added to the raw materials for preparing the continuous casting mold powder,

[0147] Among them, in the low-silicon pre-melted material, CaO and Al 2 O 3The mass ratio is 1:0.48, and the SiO content in the low-silicon premelt is 7.8 wt%; the Al content in the white fused alumina powder is 99.4 wt%; the carbon content of the carbon black is 98.2%, the oil absorption value is 127 g / cm 2 content is 99.4 wt%; the carbon content of the carbon black is 98.2%, the oil absorption value is 127 g / cm 2 O 3 content is 99.4 wt%; the carbon content of the carbon black is 98.2%, the oil absorption value is 127 g / cm 3 and the iodine absorption value is 142 g / kg; the carbon content of the graphite is 90.2 wt%, the oil absorption value is 72 g / cm 3 , and the iodine absorption value is 82 g / kg.

[0148] The continuous casting mold powder consists of the following components by mass percentage:

[0149] CaO 21.3%, Al 2 O 3 30.14%, SiO 2 5.47%, MgO 4.81%, Fe 2 O 3 0.43%, K 2 O 2.3%, Na 2 O 7.81%, F - 3.21%, C 12.12%, and the balance is volatile matter and inevitable impurities.

[0150] The melting temperature of the continuous casting mold powder is 865 °C, the viscosity at 1300 °C is 0.253 Pa·s, and the crystallization rate is 0%.

[0151] The obtained mold powder was tested in a domestic factory. The test slag model is XLG-15, the test steel type is 75V, the section is 280×380 mm 2 , and the casting speed is 0.7 - 0.9 m / min. A total of 1 T of mold powder was tested. During the test, the spreading property and fluidity of this type of mold powder were good at the initial stage of use in the mold, and the mold liquid level was stable. After using 1 furnace of steel, the slag bar generation speed became rapidly faster, the slag ring was very large, and the slag bars adhered to the mold wall, unable to maintain a stable three-layer structure,

[0152] When the total slag layer was controlled at 45 - 65 mm, the thickness of the liquid slag layer decreased from 8 - 11 mm to 5 - 7 mm at the liquid level, the slag consumption decreased from 0.48 - 0.53 kg / T to 0.25 - 0.32 kg / T, and there were 2 times of sticking alarms, with a relatively high sticking risk. There were no obvious defects on the surface of the cast billets produced during the test, but the later rolling steel test data showed that 0.61% of transverse crack defects occurred in the cast billets, which could not meet the production requirements.

[0153] In summary, the present invention controls the ratio of CaO and Al 2 O 3 to ensure that with CaO and Al2 O 3 The slag system mainly composed of CaO - Al 2 O 3 -SiO 2 The mold powder of the ternary system has a lower melting point. By introducing light rare earth ore powder, the activity of the mold powder can be effectively changed and the stability of the mold powder can be improved. The continuous casting mold powder for high - carbon high - alloy rare earth heavy rail steel provided by the present invention is applicable to the continuous casting of high - carbon high - alloy rare earth heavy rail steel with a casting speed of 0.5 - 1.10 m / min. Its design principle is unique and feasible, the selection of raw materials and the design of performance indicators are reasonable, the lubrication and heat transfer effects are good, the thickness of the liquid slag layer is uniform and moderate, which can ensure the smooth progress of the continuous casting process of high - carbon high - alloy rare earth heavy rail steel, prevent quality defects such as longitudinal cracks, transverse cracks, and porosity at the corners of the billet, effectively reduce defects such as surface corner star cracks, longitudinal cracks, edge cracks, and slag inclusions on the continuous casting billet, obtain good billet quality, reduce the grinding of the continuous casting billet, reduce the scrap rate, and lower the production cost.

[0154] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present invention, not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A continuous casting mold powder, characterized in that, the continuous casting mold powder comprises the following components by mass percentage: CaO 20 - 30%, Al 2 O 3 25 - 35%, MgO 1 - 6%, Fe 2 O 3 0.2 - 2%, K 2 O 1 - 5%, Na 2 O 6 - 10%, F - 0.5 - 4%, SiO 2 2 - 6%, C 7 - 15%, light rare earth elements 0.001 - 0.003%; Among them, the mass ratio of the CaO and Al 2 O 3 is 1:(0.8 - 1.4).

2. The continuous casting mold powder according to claim 1, characterized in that, the continuous casting mold powder consists of the following components by mass percentage: CaO 20 - 30%, Al 2 O 3 25 - 35%, MgO 1 - 6%, Fe 2 O 3 0.2 - 2%, K 2 O 1 - 5%, Na 2 O 6 - 10%, F - 0.5 - 4%, SiO 2 2 - 6%, C 7 - 15%, light rare earth elements 0.001 - 0.003%, the balance being volatile matter and / or unavoidable impurities; Preferably, the continuous casting mold powder consists of the following components by mass percentage: CaO 22 - 30%, Al 2 O 3 25 - 35%, MgO 1 - 3%, Fe 2 O 3 0.2 - 2%, K 2 O 1 - 5%, Na 2 O 6 - 10%, F - 0.5 - 4%, SiO 2 2 - 6%, C 8 - 13%, light rare earth elements 0.001 - 0.003%, the balance being volatile matter and / or unavoidable impurities.

3. The continuous casting mold powder according to claim 1, characterized in that, the raw materials for preparing the continuous casting mold powder include potassium feldspar powder, low-silicon pre-melted material, corundum powder, white soda ash, calcite, light rare earth ore powder, carbon black, graphite, cryolite, magnesia and binder.

4. The continuous casting mold powder according to claim 3, characterized in that, the raw materials for preparing the continuous casting mold powder comprise the following components by mass percentage: Potassium feldspar powder 3-15%, low-silicon pre-melted material 35-60%, corundum powder 3-15%, white soda ash 7-12%, calcite 1-10%, light rare earth ore powder 3-6%, carbon black 1-3%, graphite 6.5-14%, cryolite 2.5-7%, magnesia 1-4%, binder 0.8-2%.

5. The continuous casting mold powder according to claim 3 or 4, characterized in that, The mass ratio of CaO and Al 2 O 3 in the low-silicon premelt is 1:(0.7 - 0.9), preferably 1:0.8; and the content of SiO 2 accounts for less than 6% of the total mass of the low-silicon premelt, preferably 2 - 6%.

6. The continuous casting mold powder according to claim 3 or 4, characterized in that, The content of Al 2 O 3 in the corundum powder accounts for more than 99% of the total mass of the corundum powder.

7. The continuous casting mold powder according to claim 3 or 4, characterized in that, the light rare earth ore powder is selected from any one or a combination of at least two of light rare earth ore powders of lanthanum element, cerium element, praseodymium element, neodymium element, promethium element, samarium element or europium element.

8. The continuous casting mold powder according to claim 1, characterized in that, the melting point of the continuous casting mold powder is 850-980 °C; the viscosity of the continuous casting mold powder at 1300 °C is 0.2-0.45 Pa·s; the crystallization rate of the continuous casting mold powder is 0-10%.

9. An application of the continuous casting mold powder according to any one of claims 1-8, characterized in that, the continuous casting mold powder is applied in the production of high-carbon high-alloy rare earth heavy rail steel.

10. The application according to claim 9, characterized in that, the continuous casting mold powder is used in the continuous casting production of high-alloy rare earth heavy rail steel with a drawing speed of 0.5-1.1 m / min.