A high-lubricity and low-heat-transfer continuous casting mold powder, its preparation method and application

Abstract

The present invention relates to the technical field of auxiliary materials for steelmaking, and specifically discloses a high-lubricity and low-heat-transfer continuous casting mold powder, its preparation method and application. The continuous casting mold powder includes: 25-35% of biomass ash, 15-25% of limestone, 15-25% of wollastonite, 5-8% of fluorite, 4-6% of soda ash, 4-7% of spodumene, 3-5% of bauxite, 4.5-5% of carbon black, 5-5.5% of graphite, and 1-2% of binder; the chemical composition of the biomass ash includes: 25-35% of SiO2, 25-35% of K2O, 5-10% of CaO, 17-25% of Cl, and 0-2% of P2O5. The present invention constructs a stable slag system structure, realizes the comprehensive optimization of performances such as lubrication, heat transfer and inclusion adsorption, highly meets the special process requirements of thin slab continuous casting billets, provides reliable support for the high-quality production of thin slab continuous casting billets, and has broad application prospects.

Description

Technical Field

[0001] The present invention relates to the technical field of auxiliary materials for steelmaking, and particularly relates to a continuous casting mold powder with high lubricity and low heat transfer, and a preparation method and application thereof. Background Art

[0002] In the process of continuous casting of steel, the continuous casting mold powder plays a crucial role, and its performance directly affects the quality of the cast slab and the stability of the continuous casting process. The continuous casting mold powder needs to have functions such as preventing secondary oxidation of molten steel, heat insulation, inclusion absorption, uniform heat transfer, and improving the lubrication of the cast slab.

[0003] Traditional continuous casting mold powders use silicates, carbonates, and fluorides as raw materials. There are problems such as high cost and fluorine pollution, and the raw materials mainly rely on natural minerals (fluorite), and the resources are not sustainable. Moreover, the existing continuous casting mold powders also have certain limitations in terms of lubrication and heat transfer performance. In terms of lubrication, as the casting speed continues to increase, the vibration frequency of the mold increases, and it is difficult for the mold powder to fully flow into the channel between the cast slab and the mold, resulting in a decrease in the consumption of the mold powder and an increase in the drawing friction resistance. When the resistance exceeds the strength of the billet shell, a breakout accident is extremely likely to occur. At the same time, the increase in friction force will also cause the longitudinal crack index to rise, seriously affecting the quality of the cast slab. In terms of heat transfer performance, it is difficult for traditional mold powders to precisely control the heat transfer from the cast slab to the mold. Without using a suitable mold powder, the upper billet shell of the mold contacts the mold wall, and the cooling rate is large; while in the lower part, an air gap is generated due to the shrinkage of the billet shell, the thermal resistance increases, the heat transfer out is reduced, and the heat transfer is uneven. If the mold powder cannot form a uniform slag film, it is impossible to effectively reduce the upper heat transfer rate and increase the lower heat transfer rate, and it is difficult to improve the heat transfer uniformity.

[0004] With the rapid development of the iron and steel industry, the requirements for the continuous casting process are increasing day by day. Developing a continuous casting mold powder with high lubricity performance, which can effectively reduce the drawing resistance, reduce breakout accidents and casting slab defects, and at the same time has low heat transfer performance, can precisely control the heat transfer of the cast slab, and improve the quality of the cast slab has become an urgent problem to be solved. Summary of the Invention

[0005] Aiming at the problems in the existing continuous casting mold powder, such as the lubrication and heat transfer performance needing to be further improved, as well as high cost and environmental pollution, the present invention provides a continuous casting mold powder with high lubricity and low heat transfer, and a preparation method and application thereof. The present invention uses biomass ash with specific components as the main component, and is compounded with components such as limestone, wollastonite, and fluorite, significantly improving the lubricity and heat transfer of the mold powder. At the same time, the cost of the mold powder is significantly reduced, the resource utilization of waste is realized, and it has significant economic and environmental benefits, and has broad application prospects.

[0006] In order to solve the above technical problems, the technical solution provided by the present invention is:

[0007] In a first aspect, the present invention provides a high-lubricity and low-heat-transfer continuous casting mold powder, which comprises raw material components with the following mass percentages: 25% - 35% of biomass ash, 15% - 25% of limestone, 15% - 25% of wollastonite, 5% - 8% of fluorite, 4% - 6% of soda ash, 4% - 7% of spodumene, 3% - 5% of bauxite, 4.5% - 5% of carbon black, 5% - 5.5% of graphite, 1% - 2% of binder, and the balance being inevitable impurities;

[0008] Among them, the chemical composition of the biomass ash includes: 25% - 35% of SiO2, 25% - 35% of K2O, 5% - 10% of CaO, 17% - 25% of Cl, 0% - 2% of P2O5, 2% - 4% of Na2O, 2% - 4% of MgO, 2% - 4% of Al2O3, 3% - 5% of SO3, and the balance being inevitable impurities.

[0009] Compared with the prior art, for the continuous casting mold powder provided by the present invention, in the collaborative optimization of lubrication and heat transfer performance, the addition of biomass ash plays a key role. The K2O and Cl it contains can promote the depolymerization of the silicate structure in the mold powder, and at the same time reduce the transition temperature, enabling the mold powder to quickly form a uniform liquid slag film in the mold, reducing the drawing resistance, and achieving high lubrication performance. It can also precisely control the heat transfer process and alleviate the contradiction between lubrication and heat transfer; the Cl in the biomass ash can replace part of the F element in fluorite, reducing the content of the high-cost raw material fluorite; in addition, the biomass ash is rich in effective components such as SiO2 and CaO, which can reduce the content of raw materials such as calcium carbonate and wollastonite; and components such as K2O and MgO in the biomass ash can improve the adsorption capacity of the molten slag for inclusions such as Al2O3, further purifying the molten steel, improving the quality of the cast billet while reducing the energy consumption and resource consumption in the inclusion treatment process during smelting.

[0010] Carbon black and graphite have good lubricity. The synergistic effect of biomass ash with carbon black, graphite, and soda ash can further improve the lubricity of the mold powder; the biomass ash cooperates with raw materials such as limestone, wollastonite, and spodumene, and by reasonably adjusting the slag system composition, it can effectively control the viscosity and crystallization performance of the mold powder and improve the uniformity of heat transfer from the cast billet to the mold.

[0011] In addition, the chemical composition of biomass ash is relatively fixed, and the contents of SiO2, K2O, and CaO in biomass ash from different sources are basically the same. Therefore, when adding biomass ash in different batches, the regulating mechanism of the core properties of the mold powder is stable, reducing the impact of composition fluctuations caused by raw material differences on the properties. Additionally, traditional raw materials such as limestone, wollastonite, and fluorite cooperate with biomass ash to form a stable slag system. When the content of certain components in biomass ash fluctuates slightly, other raw materials can play a balancing and buffering role, avoiding a significant decline in performance due to composition fluctuations, thus effectively solving the problem of mold powder composition volatility.

[0012] It should be noted that in the chemical composition of the biomass ash described in the present invention, Cl represents the content of Cl element in the biomass ash.

[0013] Furthermore, the biomass ash is wheat straw ash.

[0014] As an agricultural waste, wheat straw ash is widely sourced and has a certain universality. Compared with some scarce or composition-variable raw materials, its supply is relatively stable, which can maintain the stability of the overall properties of the mold powder to a certain extent. Converting wheat straw ash into a high-value raw material for continuous casting mold powder solves the disposal problem of biomass ash and reduces its potential environmental pollution. Moreover, its cost is almost zero. Using it as the main component of the mold powder can significantly reduce the cost of the mold powder, achieving a double improvement in environmental and economic benefits.

[0015] Furthermore, the binder is starch.

[0016] Starch has good film-forming and adhesion properties, which can effectively bind the particles of each raw material of the mold powder tightly to form a stable agglomerate structure, avoiding raw material separation or dust flying during transportation and storage. Under high-temperature conditions, starch decomposes rapidly without leaving harmful substances, and the gas generated during its decomposition helps to form a porous structure, further optimizing the heat insulation performance of the mold powder and strengthening the low heat transfer effect. Additionally, starch belongs to natural organic materials, is non-toxic and harmless, and its use and decomposition processes do not pollute the environment, meeting the concept of green and sustainable development in the steel industry.

[0017] It should be noted that the chemical composition of wheat straw ash is obtained by detecting with an X-ray fluorescence spectrometer, and other impurities refer to some oxide substances contained in wheat straw, which have almost no impact on the properties of the mold powder.

[0018] Furthermore, the carbon black is semi-reinforcing carbon black.

[0019] Furthermore, the particle sizes of the limestone, wollastonite, fluorite, spodumene, and bauxite are all 0.1 mm to 1 mm.

[0020] Second aspect, the present invention also provides a preparation method of a high-lubricity and low-heat-transfer continuous casting mold powder, comprising the following steps:

[0021] S1, Weigh each raw material according to the designed ratio, mix the weighed biomass ash, limestone, wollastonite, fluorite, spodumene, bauxite and graphite evenly, heat and melt them, and after condensation, crush them to obtain a pre-melted base material;

[0022] S2, Add water to the pre-melted base material to make a slurry; add soda ash and carbon black to the slurry, mix evenly, then add a binder, and spray granulate to obtain a high-lubricity and low-heat-transfer continuous casting mold powder.

[0023] The preparation method of the continuous casting mold powder provided by the present invention first mixes, heats, melts, condenses and crushes raw materials such as biomass ash and limestone to make a pre-melted base material. This process promotes the full fusion of the components of each raw material, undergoes physical and chemical reactions, and forms a stable slag system structure. Compared with the traditional mechanical mixing method, the pre-melting treatment can effectively reduce the volatility of the components of the mold powder, make each component evenly distributed, ensure the stable performance of the mold powder during continuous casting, and give full play to the high-lubricity and low-heat-transfer characteristics. During the pre-melting process, components such as K2O and Cl in the biomass ash react synergistically with other raw materials to further optimize key performance indicators such as the melting temperature and viscosity of the slag system, ensure that the mold powder quickly forms a uniform liquid slag film, and achieve efficient lubrication and precise heat transfer control. In addition, by improving its compatibility with other raw materials through the pre-melting reaction, the usage amount of high-cost raw materials can be further reduced, and the production cost of the mold powder can be lowered.

[0024] Specifically, in S1, a shaft furnace is used to melt the biomass ash, limestone, wollastonite, fluorite, spodumene, bauxite and graphite with coke as the fuel.

[0025] Further, in S1, the particle size of the pre-melted base material is 2 mm to 3 mm.

[0026] Further, in S2, the water content of the slurry is 30% to 45%.

[0027] Further, in S2, the pressure of the spray granulation is 1.0 MPa to 3.5 MPa, and the temperature is 650 °C to 850 °C.

[0028] Further, in S2, the particle size of the high-lubricity and low-heat-transfer continuous casting mold powder is ≤ 0.25 mm, and the water content is ≤ 0.25%.

[0029] Third aspect, the present invention also provides the application of the above-mentioned high-lubricity and low-heat-transfer continuous casting mold powder in the preparation of thin slab continuous casting billets.

[0030] The drawing speed of thin slab continuous casting billets is high, and the relative movement speed between the billet and the mold wall is fast, which requires the mold powder to quickly form a uniform, appropriately thick and stable liquid slag film. At the same time, the solidification speed of thin slab continuous casting billets is fast, and the temperature gradient and solidification shrinkage non-uniformity inside the billet are prominent. The mold powder needs to have the ability to precisely regulate heat transfer. In addition, during the thin slab continuous casting process, the flow state and temperature distribution of the molten steel in the mold change more complexly. The mold powder needs to have good inclusion absorption ability to timely capture the impurities in the molten steel and prevent them from adhering to the surface of the thin slab or entering the interior, affecting the product quality. At present, it is difficult for traditional mold powders to solve the above problems simultaneously.

[0031] The mold powder provided by the present invention uses biomass ash with specific components as the main component, compounded with limestone, wollastonite, and a small amount of fluorite, soda ash, spodumene, bauxite and other components, constructing a stable slag system structure, realizing the comprehensive optimization of performance such as lubrication, heat transfer and inclusion adsorption, highly meeting the special process requirements of thin slab continuous casting billets, providing reliable support for the high-quality production of thin slab continuous casting billets, and having broad application prospects in the field of thin slab continuous casting billet production. Brief Description of the Drawings

[0032] Figure 1 It is a comparison chart of the viscosity-temperature curves of the continuous casting mold powders prepared in Example 1 and Comparative Examples 1-3 of the present invention;

[0033] Figure 2 It is a comparison chart of the heat flux density curves of the continuous casting mold powders prepared in Example 1 and Comparative Examples 1-3 of the present invention;

[0034] Figure 3 It is the XRD pattern of the continuous casting mold powders prepared in Example 1 and Comparative Examples 1-3 of the present invention. Detailed Embodiments

[0035] In order to make the purpose, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0036] To better illustrate the present invention, further examples are given below through embodiments.

[0037] Example 1

[0038] This example provides a continuous casting mold powder, which specifically includes the following raw materials in mass percentage:

[0039] Wheat straw ash 30%, limestone 17%, wollastonite 18%, fluorite 6%, soda ash 5%, spodumene 6%, bauxite 5%, semi-reinforcing carbon black 4.6%, graphite 5.4%, starch 1.7%, and the rest are inevitable impurities;

[0040] Among them, the chemical components of wheat straw ash include: SiO2 29%, K2O 31%, CaO 5.8%, Cl 19.8%, P2O5 1.2%, Na2O 2.3%, MgO 3.6%, Al2O3 3.9%, SO3 3.1%, and the balance is other impurities.

[0041] The preparation method of the above continuous casting mold powder specifically includes the following steps:

[0042] S1, Weigh each component according to the designed ratio. Among them, the particle sizes of limestone, wollastonite, fluorite, spodumene, and bauxite in the above raw materials are 0.5 mm;

[0043] S2, Mix the wheat straw ash, limestone, wollastonite, fluorite, spodumene, bauxite, and graphite evenly, and use coke as fuel in a shaft furnace for melting. After condensation and crushing, it becomes a pre-melted base material with a diameter of 2.0 mm;

[0044] S3, Thoroughly mechanically stir the pre-melted base material and adjust the slurry with water. Control the water content at 38%; add the weighed soda ash and carbon black for pre-stirring, then add the weighed binder. After stirring and grinding into a slurry, the slurry is transported by a slurry pump and sprayed in a spray tower at a pressure of 2.5 MPa. Control the spraying temperature at 830 °C;

[0045] S4, Cool it in a silo to below 55 °C to obtain the finished mold powder product, with an average particle size of 0.18 mm and a water content of 0.18%.

[0046] The melting point of the above-prepared mold powder is measured by the semi-melting point method to be 1045 °C. The viscosity-temperature curve of the mold powder is measured by a high-temperature viscometer, as Figure 1 shown, where the viscosity at 1300 °C is 0.151 Pa . s, and the transition temperature is 1195 °C. The heat flux density of the mold powder is measured by a high-temperature infrared molten slag heat transfer performance test device, as Figure 2 shown, where the heat flux density at the highest point is 195 kW / m 2 . The crystal phase of the mold powder is measured by an X-ray diffractometer, as Figure 3 shown.

[0047] Example 2

[0048] This example provides a continuous casting mold powder, which specifically includes the following raw materials with mass percentages:

[0049] Wheat straw ash 25%, limestone 23%, wollastonite 15%, fluorite 8%, soda ash 4%, spodumene 7%, bauxite 4%, semi-reinforcing carbon black 5%, graphite 5.5%, starch 2%, and the rest are inevitable impurities;

[0050] Among them, the chemical components of wheat straw ash include: SiO2 25%, K2O 25%, CaO 9.8%, Cl 24.6%, P2O5 1.8%, Na2O 3%, MgO 3.8%, Al2O3 2.5%, SO3 3.4%, and the balance is other impurities.

[0051] The preparation method of the continuous casting mold powder described above specifically includes the following steps:

[0052] S1, Weigh each component according to the designed ratio. Among them, the particle sizes of limestone, wollastonite, fluorite, spodumene, and bauxite in the above raw materials are 0.2 mm;

[0053] S2, Mix the wheat straw ash, limestone, wollastonite, fluorite, spodumene, bauxite, and graphite evenly, and use coke as fuel in a shaft furnace for melting. After condensation and crushing, it becomes a pre-melted base material with a diameter of 2.7 mm;

[0054] S3, Thoroughly mechanically stir the pre-melted base material and adjust the slurry with water. The water content is controlled at 33%; Add the weighed soda ash and carbon black for pre-stirring, then add the weighed binder, stir and grind the slurry. The slurry is transported by a slurry pump and sprayed in a spray tower at a pressure of 2.7 MPa. The spraying temperature is controlled at 810 °C;

[0055] S4, Cool it in a silo to below 55 °C to obtain the finished mold powder. The average particle size is 0.21 mm and the water content is 0.19%.

[0056] Example 3

[0057] This example provides a continuous casting mold powder, which specifically includes the following raw materials with mass percentages:

[0058] Wheat straw ash 35%, limestone 15%, wollastonite 20%, fluorite 5%, soda ash 6%, spodumene 4%, bauxite 3%, semi-reinforcing carbon black 4.5%, graphite 5%, starch 1%, and the rest are inevitable impurities;

[0059] Among them, the chemical components of wheat straw ash include: SiO2 35%, K2O 27%, CaO 7.4%, Cl 18.6%, P2O5 0.3%, Na2O 2.5%, MgO 2%, Al2O3 2.1%, SO3 4.2%, and the balance is other impurities.

[0060] The preparation method of the continuous casting mold powder described above specifically includes the following steps:

[0061] S1, Weigh each component according to the designed ratio. Among them, the particle sizes of limestone, wollastonite, fluorite, spodumene and bauxite in the above raw materials are 0.6 mm;

[0062] S2, Mix the wheat straw ash, limestone, wollastonite, fluorite, spodumene, bauxite and graphite evenly, and use coke as fuel to melt them in a shaft furnace. After condensation and crushing, a pre-melted base material with a diameter of 2.6 mm is obtained;

[0063] S3, Thoroughly mechanically stir the pre-melted base material and adjust the slurry with water. Control the water content at 31%; add the weighed soda ash and carbon black for pre-stirring, then add the weighed binder. After stirring and grinding into a slurry, the slurry is transported by a slurry pump and sprayed in a spray tower at a pressure of 2.1 MPa. Control the spraying temperature at 720 °C;

[0064] S4, Cool it in a silo to below 55 °C to obtain the finished product of the mold powder. The average particle size is 0.23 mm and the water content is 0.16%.

[0065] Example 4

[0066] This example provides a continuous casting mold powder, which specifically includes raw materials with the following mass percentages:

[0067] Wheat straw ash 25%, limestone 22%, wollastonite 25%, fluorite 5%, soda ash 4%, spodumene 4%, bauxite 3%, semi-reinforcing carbon black 4.5%, graphite 5.2%, starch 1%, and the rest are inevitable impurities;

[0068] Among them, the chemical composition of the wheat straw ash includes: SiO2 28%, K2O 35%, CaO 5.3%, Cl 17.3%, P2O5 0.9%, Na2O 3.8%, MgO 2.2%, Al2O3 2.3%, SO3 4.9%, and the balance is other impurities.

[0069] The preparation method of the above continuous casting mold powder specifically includes the following steps:

[0070] S1, Weigh each component according to the designed ratio. Among them, the particle sizes of limestone, wollastonite, fluorite, spodumene and bauxite in the above raw materials are 1.0 mm;

[0071] S2, Mix the wheat straw ash, limestone, wollastonite, fluorite, spodumene, bauxite and graphite evenly, and use coke as fuel to melt them in a shaft furnace. After condensation and crushing, a pre-melted base material with a diameter of 2.3 mm is obtained;

[0072] S3. Thoroughly mechanically stir the premelted base material and add water to make a slurry, with the water content controlled at 43%; add the previously weighed soda ash and carbon black for pre-stirring, then add the weighed binder, stir and grind into a slurry, and the slurry is transported by a slurry pump and sprayed in a spraying tower at a pressure of 3.5 MPa, with the spraying temperature controlled at 680 °C;

[0073] S4. Cool it in a silo to below 55 °C to obtain the finished product of the mold powder, with an average particle size of 0.17 mm and a water content of 0.22%.

[0074] Example 5

[0075] This example provides a continuous casting mold powder, which specifically includes raw materials with the following mass percentages:

[0076] Wheat straw ash: 25%, limestone: 25%, wollastonite: 16%, fluorite: 7%, soda ash: 5.2%, spodumene: 5%, bauxite: 3.7%, semi-reinforcing carbon black: 4.7%, graphite: 5.6%, starch: 1.5%, and the rest are inevitable impurities;

[0077] Among them, the chemical composition of the wheat straw ash includes: SiO2 31%, K2O 29%, CaO 8.1%, Cl 20.6%, P2O5 1.5%, Na2O 2.2%, MgO 2.1%, Al2O3 2.2%, SO3 3.1%, and the balance is other impurities.

[0078] The preparation method of the above continuous casting mold powder specifically includes the following steps:

[0079] S1. Weigh each component according to the designed ratio. Among them, the particle sizes of limestone, wollastonite, fluorite, spodumene, and bauxite in the above raw materials are 0.4 mm;

[0080] S2. Mix the wheat straw ash, limestone, wollastonite, fluorite, spodumene, bauxite, and graphite evenly, and use coke as fuel to melt in a shaft furnace, and then condense and crush it into a premelted base material with a diameter of 3.0 mm;

[0081] S3. Thoroughly mechanically stir the premelted base material and add water to make a slurry, with the water content controlled at 36%; add the previously weighed soda ash and carbon black for pre-stirring, then add the weighed binder, stir and grind into a slurry, and the slurry is transported by a slurry pump and sprayed in a spraying tower at a pressure of 3.0 MPa, with the spraying temperature controlled at 750 °C;

[0082] S4. Cool it in a silo to below 55 °C to obtain the finished product of the mold powder, with an average particle size of 0.23 mm and a water content of 0.24%.

[0083] The continuous casting mold fluxes prepared in Examples 2 to 5 can all achieve lubrication and heat transfer control effects equivalent to those in Example 1. The viscosity at 1300 °C is 0.140 - 0.160 Pa . s, the transition temperature is 1180 - 1205 °C, and the heat flux density at the highest point is 185 - 203 kW / m 2 .

[0084] Comparative Example 1

[0085] This comparative example provides a continuous casting mold flux. The only difference from Example 1 is that wheat straw ash is replaced with an equal amount of corn straw ash. The chemical composition of the corn straw ash includes: SiO2 13.5%, K2O 36.5%, CaO 7.8%, Cl 11.7%, P2O5 9.5%, Na2O 1.3%, MgO 16.2%, Al2O3 0.6%, SO3 2.3%, and the balance is other impurities.

[0086] The chemical composition of the continuous casting mold flux is as follows:

[0087] Corn straw ash 30%, limestone 17%, wollastonite 18%, fluorite 6%, soda ash 5%, spodumene 6%, bauxite 5%, semi-reinforcing carbon black 4.6%, graphite 5.4%, starch 1.7%, and the rest are inevitable impurities.

[0088] The preparation method of the above continuous casting mold flux is exactly the same as that in Example 1 and will not be elaborated here.

[0089] The melting point of the flux was measured by the semi-melting point method to be 1050 °C. The viscosity-temperature curve of the flux was measured by a high-temperature viscometer, as Figure 1 shown, where the viscosity at 1300 °C is 0.278 Pa . s, and the transition temperature is 1231 °C. The heat flux density of the flux was measured by a high-temperature infrared molten slag heat transfer performance test device, as Figure 2 shown, where the heat flux density at the highest point is 250 kW / m 2 . The crystalline phase of the flux was measured by an X-ray diffractometer, as Figure 3 shown.

[0090] Comparative Example 2

[0091] This comparative example provides a traditional continuous casting mold flux, including the following components in mass percentage:

[0092] Wollastonite 56%, fluorite 9%, soda ash 8%, spodumene 3%, glass powder 9%, bauxite 3%, carbon black 4.7%, graphite 5.3%, binder 1.9%, and the rest are inevitable impurities.

[0093] The preparation method of the above continuous casting mold powder includes the following steps:

[0094] S1, Weigh each component according to the designed ratio. Among them, the particle sizes of wollastonite, fluorite, glass powder, spodumene and bauxite in the above raw materials are 0.5 mm;

[0095] S2, Mix the wollastonite, fluorite, glass powder, spodumene, bauxite and graphite evenly, use coke as fuel in a shaft furnace for melting, and after condensation and crushing, form a pre-melted base material with a diameter of 2.0 mm;

[0096] S3, Thoroughly mechanically stir the pre-melted base material and adjust the slurry with water, controlling the water content at 39%; Add the weighed soda ash and carbon black for pre-stirring, then add the weighed binder, stir and grind the slurry, and the slurry is transported by a slurry pump and sprayed in a spray tower at a pressure of 2.5 MPa, controlling the spraying temperature at 830 °C;

[0097] S4, Cool in a silo to below 55 °C to obtain the finished mold powder, with an average particle size of 0.19 mm and a water content of 0.19%.

[0098] The melting point of the above-prepared mold powder is measured by the semi-melting point method to be 1070 °C. The viscosity-temperature curve of the mold powder is measured by a high-temperature viscometer, as Figure 1 shown, where the viscosity at 1300 °C is 0.139 Pa . s, and the transition temperature is 1227 °C. The heat flux density of the mold powder is measured by a high-temperature infrared molten slag heat transfer performance test device, as Figure 2 shown, where the heat flux density at the highest point is 254 kW / m 2 . The crystal phase of the mold powder is measured by an X-ray diffractometer, as Figure 3 shown.

[0099] Comparative Example 3

[0100] This comparative example provides a continuous casting mold powder. The only difference from Example 1 is that wheat straw ash is replaced with an equal amount of rice straw ash. The chemical composition of the rice straw ash includes: SiO2 15.8%, K2O 23.5%, CaO 20.3%, Cl 10.8%, P2O5 6.7%, Na2O 0.6%, MgO 12.3%, Al2O3 1.6%, SO3 5.8%, and the balance is other impurities.

[0101] The chemical composition of the continuous casting mold powder is:

[0102] Rice straw ash 30%, limestone 17%, wollastonite 18%, fluorite 6%, soda ash 5%, spodumene 6%, bauxite 5%, semi-reinforcing carbon black 4.6%, graphite 5.4%, starch 1.7%, and the rest are inevitable impurities.

[0103] The preparation method of the continuous casting mold powder described above is exactly the same as that of Example 1, and will not be elaborated here.

[0104] The melting point of the mold powder was measured to be 1055 °C by the semi-melting point method. The viscosity-temperature curve of the mold powder was measured by a high-temperature viscometer, as Figure 1 shown, and the viscosity at 1300 °C was 0.256 Pa . s, and the turning temperature was 1223 °C. The heat flux density of the mold powder was measured by a high-temperature infrared molten slag heat transfer performance test device, as Figure 2 shown, and the heat flux density at the highest point was 242 kW / m 2 . The crystalline phase of the mold powder was measured by an X-ray diffractometer, as Figure 3 shown.

[0105] In summary, the performance and parameters of the continuous casting mold powder containing wheat straw ash prepared in the embodiments of the present invention, such as the turning temperature and heat flux density, are superior to those of the traditional continuous casting mold powder, and can effectively improve lubrication and control heat transfer during continuous casting. For the continuous casting mold powder containing corn straw ash described in Comparative Example 1 and the continuous casting mold powder containing rice straw ash described in Comparative Example 3, due to the relatively high P2O5 and low Cl content in corn straw ash and rice straw ash, their lubrication performance deteriorates and it is difficult to meet the requirements of thin slab continuous casting.

[0106] From the XRD results of the examples and comparative examples, the mineral phase composition of the mold powder prepared in the examples is basically the same as that of the traditional mold powder. It can be seen that the mineral phase composition of the mold powder added with wheat straw ash is relatively stable. Therefore, the present invention effectively improves the lubrication effect and heat transfer control ability of the continuous casting mold powder, thereby ensuring the smooth progress of the continuous casting process. At the same time, it also reduces the cost and fluorine content of the mold powder, having both economic and environmental benefits.

[0107] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, or improvements made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A high-lubrication and low-heat-transfer continuous casting mold powder, characterized in that The raw material components include the following mass percentages: 25% - 35% biomass ash, 15% - 25% limestone, 15% - 25% wollastonite, 5% - 8% fluorite, 4% - 6% soda ash, 4% - 7% spodumene, 3% - 5% bauxite, 4.5% - 5% carbon black, 5% - 5.5% graphite, 1% - 2% binder, and the balance is inevitable impurities; Among them, the chemical composition of the biomass ash includes: 25% - 35% SiO2, 25% - 35% K2O, 5% - 10% CaO, 17% - 25% Cl, 0% - 2% P2O5, 2% - 4% Na2O, 2% - 4% MgO, 2% - 4% Al2O3, 3% - 5% SO3, and the balance is other impurities.

2. The high-lubricity and low-heat-transfer continuous casting mold powder according to claim 1, characterized in that, The biomass ash is wheat straw ash.

3. The high-lubricity and low-heat-transfer continuous casting mold powder according to claim 1, characterized in that, The binder is starch.

4. The high-lubricity and low-heat-transfer continuous casting mold powder according to claim 1, wherein The carbon black is semi-reinforcing carbon black.

5. The high-lubricity and low-heat-transfer continuous casting mold powder according to claim 1, wherein The particle sizes of the limestone, wollastonite, fluorite, spodumene, and bauxite are all 0.1 mm - 1 mm.

6. A method for preparing a high-lubricity and low-heat-transfer continuous casting mold powder according to any one of claims 1 to 5, characterized in that, It includes the following steps: S1, Weigh each raw material according to the designed ratio, mix the weighed biomass ash, limestone, wollastonite, fluorite, spodumene, bauxite, and graphite evenly, heat and melt them, and after condensation, crush them to obtain a pre-melted base material; S2, Add water to the pre-melted base material to make a slurry; add soda ash and carbon black to the slurry, mix them evenly, then add the binder, and spray granulate to obtain a high-lubricity and low-heat-transfer continuous casting mold powder.

7. The preparation method of the high-lubricity and low-heat-transfer continuous casting mold powder according to claim 6, characterized in that, In S1, the particle size of the pre-melted base material is 2 mm - 3 mm.

8. The preparation method of the high-lubricity and low-heat-transfer continuous casting mold powder according to claim 6, characterized in that, In S2, the water content of the slurry is 30% - 45%; and / or In S2, the pressure of the spray granulation is 1.0 MPa - 3.5 MPa, and the temperature is 650 °C - 850 °C.

9. The preparation method of the high-lubricity and low-heat-transfer continuous casting mold powder according to claim 6, characterized in that, In S2, the particle size of the high-lubricity and low-heat-transfer continuous casting mold powder is ≤0.25 mm, and the water content is ≤0.25%.

10. The application of the high-lubricity and low-heat-transfer continuous casting mold powder according to any one of claims 1 - 5 in the preparation of thin slab continuous casting billets.

Images