Low basicity ladle slag modifying heat insulating agent and preparation method thereof

Abstract

The present application relates to a kind of low basicity ladle slag modification heat insulating agent and its preparation method, the heat insulating agent includes the following components: including the following mass percentages: calcite 10~30%, cement clinker 5~25%, carbide slag 5~25%, dolomite 10~30% and magnesium carbon recovery material 10~20%.Low basicity ladle slag modification heat insulating agent of the present application, after melting, combined with refining slag to form the basicity>1 of ladle slag, realizes the modification to low basicity ladle slag, and the basicity and MgO content increase, weaken the erosion of steel slag to alkaline ladle lining material, it is favorable to prolong the service life of ladle alkaline working lining, reduce refractory consumption and ton steel refractory cost, and economic benefit is remarkable.

Description

Technical Field

[0001] This invention relates to the field of auxiliary materials technology for continuous casting metallurgy, specifically to a low-basicity ladle slag modified heat-insulating agent and its preparation method. Background Technology

[0002] With the continuous development of society, the demand for various types of steel is increasing. Ladle refining is an essential process in the production of specialty steels. Selecting the appropriate refining slag system based on different steel grades is crucial. Compared to the high-basicity slag used in general refining, some specialty steels, such as silicon steel, bearing steel, and hardened wire steel, require slag with very low basicity during smelting. This slag is characterized by high oxidizing power, low viscosity, and high magnesium oxide solubility, which exacerbates the damage to the basic refractory lining of the ladle. The service life of the ladle is significantly reduced, and in severe cases, it can affect the production rhythm of the steel plant. Simultaneously, the amount of refractory material used for the lining increases, leading to higher refractory material consumption per ton of steel and increased smelting costs. Therefore, research on high-performance and long-life basic lining materials for ladles under low-basicity slag smelting conditions has become a bottleneck issue. Summary of the Invention

[0003] The technical problem this invention aims to solve is the corrosion of ladle lining materials by existing low-basicity slag during smelting. This invention reduces the corrosion of ladle slag lining materials during continuous casting by adjusting the composition of the insulating agent to alter the basicity of the slag.

[0004] The technical solution of the present invention to solve the above-mentioned technical problems is as follows:

[0005] A low-alkalinity steel ladle slag modified thermal insulation agent comprises the following components in the following mass percentages: calcite 10-30%, cement clinker 5-25%, carbide slag 5-25%, dolomite 10-30%, and magnesium-carbon recycled material 10-20%.

[0006] The principle of this invention is as follows: After melting, the insulating agent combines with the ladle slag to cover the molten steel. By adjusting the composition of the insulating agent, the basicity of the ladle slag can be changed, thus reducing the erosion of the ladle lining material by the ladle slag during continuous casting. Slag basicity usually refers to binary basicity, i.e., the CaO% / SiO2% value. Calcite and calcium carbide slag are raw materials with CaO as the main component, cement clinker is a high CaO / SiO2 raw material, dolomite can provide both CaO and MgO, and magnesium-carbon recycled material is mainly composed of MgO and carbon materials. Through the reasonable combination of the above raw materials, an alkaline insulating agent with a reasonable basicity can be designed. After melting, it reacts with low-basicity ladle slag to form a high-basicity slag system, increasing the viscosity of the molten slag and reducing the erosion of the basic ladle working lining. The typical ladle lining is made of magnesium-carbon material, and the slag has a high MgO content, which reduces the dissolution loss of MgO in the magnesium-carbon material and extends the service life of the ladle lining.

[0007] The beneficial effects of this invention are as follows: The low-alkalinity ladle slag modifier of this invention, after melting, combines with ladle refining slag to form high-alkalinity ladle slag, thereby modifying the low-alkalinity ladle slag, increasing the alkalinity and MgO content, reducing the erosion of alkaline lining materials by steel slag, which is beneficial to extending the service life of alkaline working linings of ladles, reducing refractory material consumption and refractory material cost per ton of steel, resulting in significant economic benefits.

[0008] Based on the above technical solution, the present invention can be further improved as follows.

[0009] Furthermore, the proportion of particles with a particle size of 0.1 to 1.5 mm in the heat-insulating agent exceeds 85%.

[0010] The beneficial effects of adopting the above-mentioned further solutions are:

[0011] Furthermore, it also includes a binder, wherein the binder is at least one selected from dextrin, calcium lignosulfonate, and carboxymethyl cellulose;

[0012] The amount of binder used is 1 to 2% of the total mass of the calcite, cement clinker, carbide slag, dolomite, and magnesium carbon recycled material.

[0013] The beneficial effects of adopting the above-mentioned further solutions are: the binder forms a bond strength after the insulating agent particles dry; the use of organic binders results in their disappearance after high temperatures, minimizing the impact on the insulating agent composition; and the combined use of binders can increase the consistency and suspension of the slurry, as well as its strength after drying.

[0014] The calcite, cement clinker, carbide slag, dolomite, magnesium carbon recycled material, and binder are all uniform powders, with at least 90% of the powder having a particle size less than 0.088 mm by mass, and the water content in the powder not exceeding 1% by mass.

[0015] The beneficial effects of adopting the above-mentioned further solution are: if the proportion of powder particles with a diameter <0.088mm is low, it will lead to uneven mud, poor suspension, and large particles may cause clogging of the spray gun.

[0016] Furthermore, the cement clinker is silicate cement clinker, and the mass contents of SiO2, CaO and Al2O3 in the cement clinker are 20-25%, 60-70% and 5-10%, respectively.

[0017] The beneficial effect of adopting the above-mentioned further scheme is that cement clinker simultaneously provides multiple components such as SiO2, CaO and Al2O3, which makes it easier for the thermal insulation agent to adjust the alkalinity and melting point.

[0018] Furthermore, the mass content of CaO in the carbide slag is 60-70%.

[0019] The beneficial effects of adopting the above-mentioned further scheme are: carbide slag is a high-calcium solid waste material, which is abundant and low in cost, thereby reducing the cost of insulation agents and improving the utilization rate of resources.

[0020] It should be noted that calcium carbide slag is a dry-based solid waste with Ca(OH)2 as its main component, produced during the hydrolysis of calcium carbide to produce acetylene.

[0021] Furthermore, the dolomite contains more than 30% CaO and more than 20% MgO by mass.

[0022] The magnesium-carbon recycled material contains more than 50% MgO by mass and more than 10% C by mass.

[0023] The beneficial effects of adopting the above-mentioned further scheme are: dolomite resources are abundant and inexpensive, and can provide alkaline components such as CaO and MgO at the same time; magnesium carbon recycled material is a recycling of waste resources, with low cost, and provides MgO and carbon materials at the same time. MgO is used to increase the MgO content of the thermal insulation agent, and carbon materials can be used to adjust the melting rate of the thermal insulation agent.

[0024] It should be noted that: magnesium carbon recycled material refers to recycled magnesium carbon bricks used in steel ladles or converters, or dust generated during the production of magnesium carbon bricks.

[0025] To achieve the second objective mentioned above, this invention provides a method for preparing a low-alkalinity ladle slag modified insulation agent, comprising:

[0026] Calcite, cement clinker, carbide slag, dolomite, and magnesium carbon recycled material are mixed evenly to obtain premixed powder;

[0027] The premixed powder is mixed with water and binder and stirred to obtain thermal insulation slurry;

[0028] The heat-insulating agent slurry is sieved, atomized into dispersed droplets, and dried into hollow spherical particles by hot air drying.

[0029] The hollow spherical particles were sieved to obtain a low-alkalinity steel ladle slag modified thermal insulation agent.

[0030] The beneficial effects are: the use of spray granulation process to produce thermal insulation agent can produce hollow spherical granules with a lower density than traditional powder or granule products, which gives the thermal insulation agent better insulation, flowability and spreadability, and at the same time, there are no environmental problems such as dust pollution during use.

[0031] Furthermore, the amount of water used is 50-70% of the total mass of the calcite, cement clinker, carbide slag, dolomite, and magnesium carbon recycled material.

[0032] The beneficial effect of adopting the above-mentioned further scheme is that by controlling the amount of water added, a slurry with appropriate viscosity and fluidity can be obtained, which is more conducive to the implementation of the spray granulation process.

[0033] Furthermore, the stirring includes: first stirring at a stirring speed of 120 r / min for 40 to 50 minutes, and then stirring at a stirring speed of 60 r / min for 30 to 40 minutes;

[0034] The temperature of the drying hot air is 500-600℃.

[0035] The beneficial effects of adopting the above-mentioned further solutions are: the spray granulation process should adopt a suitable hot air drying temperature. If the temperature is too low, the moisture content of the finished product will be too high; if the temperature is too high, the particle strength will be too low, the particles will be brittle, and the drying cost will increase. Detailed Implementation

[0036] The principles and features of this invention are described below. The examples given are for illustrative purposes only and are not intended to limit the scope of the invention. Where specific techniques or conditions are not specified in the embodiments, they should be performed according to the techniques or conditions described in the literature in this field, or according to the product instructions. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased through legitimate channels.

[0037] The following are descriptions of the experimental materials and reagents:

[0038] Calcite: a natural mineral raw material, containing 96% CaCO3 by mass, with other components being negligible.

[0039] Cement clinker: Silicate cement clinker, containing the following components: 23% SiO2 by mass, 65% CaO by mass, 8% Al2O3 by mass, and other components are negligible.

[0040] Calcium carbide slag: Dry-based solid waste produced during the hydrolysis of calcium carbide to produce acetylene, with Ca(OH)2 as the main component. Its composition is: CaO content 65% by mass, with a large amount remaining, and the remainder being water of crystallization.

[0041] Dolomite: A natural mineral raw material containing 40% CaO and 25% MgO, with other components being negligible.

[0042] Magnesium-carbon recycled material: recycled material from magnesium-carbon bricks used in steel ladles or converters, or dust generated during the production of magnesium-carbon bricks. Its composition is: 54% MgO by mass, 15% C by mass, and other components are negligible.

[0043] Example 1

[0044] A method for preparing a low-alkalinity steel ladle slag modified thermal insulation agent includes:

[0045] (1) Mix 30 parts calcite, 10 parts cement clinker, 20 parts calcium carbide slag, 30 parts dolomite, and 10 parts magnesium carbon recycled material evenly to obtain premixed powder;

[0046] (2) Add the premixed powder, 65 parts water, 1 part dextrin and 0.5 parts calcium lignosulfonate to a pulping machine and mix for 80 minutes to obtain thermal insulation slurry;

[0047] (3) The thermal insulation agent slurry is pumped out by a slurry pump and injected into a mixer. It is first stirred at a stirring speed of 120r / min for 45min, and then stirred at a stirring speed of 60r / min for 35min. After being filtered by a vibrating screen, it is then pressurized by a plunger pump and injected into the spray granulation tower spray gun.

[0048] (4) The thermal insulation agent slurry is atomized into dispersed droplets by spray gun in the spray granulation tower, and meets the 550°C dry hot air entering the tower from the top of the tower, instantly evaporating the water in the droplets to form hollow spherical particles.

[0049] (5) Hollow spherical particles are fed through the discharge port to a vibrating screen for screening to obtain a low-alkalinity steel ladle slag modified insulation agent with qualified particle size.

[0050] The calcite, cement clinker, carbide slag, dolomite, magnesium carbon recycled material, and binder used in this embodiment are all uniform powders. The mass percentage of particles with a diameter less than 0.088 mm in the powder is not less than 90%, and the mass content of water in the powder is not higher than 1%.

[0051] Example 2

[0052] A method for preparing a low-alkalinity steel ladle slag modified thermal insulation agent includes:

[0053] (1) Mix 10 parts calcite, 25 parts cement clinker, 20 parts calcium carbide slag, 30 parts dolomite, and 15 parts magnesium carbon recycled material evenly to obtain premixed powder.

[0054] (2) Add the premixed powder, 60 parts water, 1.5 parts dextrin and 0.3 parts calcium lignosulfonate to a pulping machine and mix for 70 minutes to obtain thermal insulation slurry;

[0055] (3) The thermal insulation agent slurry is pumped out by a slurry pump and injected into a mixer. It is first stirred at a stirring speed of 120r / min for 40min, then stirred at a stirring speed of 60r / min for 30min. After being filtered by a vibrating screen, it is then pressurized by a plunger pump and injected into the spray granulation tower spray gun.

[0056] (4) The thermal insulation agent slurry is sprayed into dispersed droplets in the spray granulation tower by the spray gun, and meets the 600℃ dry hot air entering the tower from the top of the tower, instantly evaporating the water in the droplets to form hollow spherical particles;

[0057] (5) Hollow spherical particles are fed through the discharge port to a vibrating screen for screening to obtain a low-alkalinity steel ladle slag modified insulation agent with qualified particle size.

[0058] The calcite, cement clinker, carbide slag, dolomite, magnesium carbon recycled material, and binder used in this embodiment are all uniform powders. The mass percentage of particles with a diameter less than 0.088 mm in the powder is not less than 90%, and the mass content of water in the powder is not higher than 1%.

[0059] Example 3

[0060] A method for preparing a low-alkalinity steel ladle slag modified thermal insulation agent includes:

[0061] (1) Mix 20 parts calcite, 15 parts cement clinker, 30 parts calcium carbide slag, 15 parts dolomite, and 20 parts magnesium carbon recycled material evenly to obtain premixed powder.

[0062] (2) Add the premixed powder, 65 parts water, 1 part dextrin and 0.5 parts calcium lignosulfonate to a pulping machine and mix for 70 minutes to obtain thermal insulation slurry;

[0063] (3) The thermal insulation agent slurry is pumped out by a slurry pump and injected into a mixer. It is first stirred at a stirring speed of 120r / min for 50min, and then stirred at a stirring speed of 60r / min for 40min. After being filtered by a vibrating screen, it is then pressurized by a plunger pump and injected into the spray granulation tower spray gun.

[0064] (4) The thermal insulation agent slurry is atomized into dispersed droplets by spray gun in the spray granulation tower, and meets the 580°C dry hot air entering the tower from the top of the tower, instantly evaporating the water in the droplets to form hollow spherical particles.

[0065] (5) Hollow spherical particles are fed through the discharge port to a vibrating screen for screening to obtain a low-alkalinity steel ladle slag modified insulation agent with qualified particle size.

[0066] The calcite, cement clinker, carbide slag, dolomite, magnesium carbon recycled material, and binder used in this embodiment are all uniform powders. The mass percentage of particles with a diameter less than 0.088 mm in the powder is not less than 90%, and the mass content of water in the powder is not higher than 1%.

[0067] Comparative Example 1

[0068] Traditional ladle insulation agents are mostly powdered products, with fly ash (SiO2 > 45%, Al2O3 > 30%) as the main raw material. They have good insulation performance, but melt quickly, require large amounts, and are acidic. They cannot modify low-alkalinity ladle slag and are highly corrosive to alkaline ladle linings during use.

[0069] The thermal insulation agents obtained in the examples and comparative examples were tested and their performance was evaluated. The results are shown in Table 1.

[0070] Table 1 shows the test results and performance evaluation results of the thermal insulation agents obtained in the examples and comparative examples.

[0071]

[0072] The above data compares the effects of using the modified thermal insulation agent on a 150-ton steel ladle. It can be seen that compared with the original powdered thermal insulation agent, the modified thermal insulation agent of this invention reduces the consumption per ton of steel, extends the service life of the steel ladle, and has good spreadability during use, without causing dust or other environmental problems.

[0073] In summary, the insulating agent of the present invention can combine with the refining slag after melting to form ladle slag with an alkalinity >1, thereby reducing the erosion of the alkaline working lining of the ladle and extending the service life of the refractory material of the ladle lining.

[0074] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0075] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A low-alkalinity steel ladle slag modified thermal insulation agent, characterized in that, It includes the following components by mass percentage: calcite 10-30%, cement clinker 5-25%, carbide slag 5-25%, dolomite 10-30%, and magnesium carbon recycled material 10-20%. It also includes a binder, wherein the calcite, the cement clinker, the carbide slag, the dolomite, the magnesium carbon recycled material and the binder are all uniform powders, wherein the mass percentage of the powder with a particle size less than 0.088 mm is not less than 90%, and the mass content of the powder with water is not more than 1%. The cement clinker is silicate cement clinker, and the mass contents of SiO2, CaO and Al2O3 in the cement clinker are 20-25%, 60-70% and 5-10%, respectively. The mass content of CaO in the carbide slag is 60-70%; The dolomite contains more than 30% CaO by mass and more than 20% MgO by mass. The magnesium-carbon recycled material contains more than 50% MgO by mass and more than 10% C by mass. The preparation method of the low-alkalinity ladle slag modified insulation agent includes: Calcite, cement clinker, carbide slag, dolomite, and magnesium carbon recycled material are mixed evenly to obtain premixed powder; The premixed powder is mixed with water and binder and stirred to obtain thermal insulation slurry; The heat-insulating agent slurry is sieved, atomized into dispersed droplets, and dried into hollow spherical particles by hot air drying. The hollow spherical particles were sieved to obtain a low-alkalinity steel ladle slag modified thermal insulation agent.

2. The low-alkalinity ladle slag modified insulation agent according to claim 1, characterized in that, The thermal insulation agent contains more than 85% particles with a particle size of 0.1 to 1.5 mm.

3. The low-alkalinity ladle slag modified insulation agent according to claim 1, characterized in that, The binder is at least one of dextrin, calcium lignosulfonate and carboxymethyl cellulose; The amount of binder used is 1 to 2% of the total mass of the calcite, cement clinker, carbide slag, dolomite, and magnesium carbon recycled material.

4. The low-alkalinity ladle slag modified insulation agent according to claim 1, characterized in that, The amount of water used is 50-70% of the total mass of the calcite, cement clinker, carbide slag, dolomite, and magnesium carbon recycled material.

5. The low-alkalinity ladle slag modified insulation agent according to claim 1, characterized in that, The stirring includes: first stirring at a stirring speed of 120 r / min for 40-50 min, and then stirring at a stirring speed of 60 r / min for 30-40 min; The temperature of the drying hot air is 500-600℃.

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