Gunning mix for RH insert tube, composition of gunning mix and preparation method of gunning mix

Abstract

The invention relates to the field of refractory materials, and discloses a gunning mix for an RH insert tube, a composition of the gunning mix and a preparation method of the gunning mix. Wherein the dry material comprises the following components in percentage by mass: 30-40% of a waste magnesite brick reclaimed material with the particle size of 0-3mm and the MgO content of 82-87%, 30-40% of sintered magnesia with the particle size of 0-3mm, 20-25% of medium-grade magnesia with the particle size of less than 0.088 mm, 1-5% of silica fume and 2-6% of a binding agent; the mass of the water is 15-21% of the mass of the dry material. The bonding performance and the slag resistance of the gunning material can be improved.

Description

Technical Field

[0001] This invention relates to the field of refractory materials technology, specifically to a spraying compound for RH insertion tubes, its composition, and its preparation method. Background Technology

[0002] The RH refining method is a process that improves the purity of molten steel by removing harmful gases such as hydrogen, oxygen, and nitrogen, as well as inclusions, through steel circulation in a vacuum environment. The RH vacuum refining furnace used in the RH refining method includes a vacuum chamber and two insertion pipes connected to the bottom of the vacuum chamber. One insertion pipe draws molten steel from the ladle into the vacuum chamber, while the other insertion pipe discharges the molten steel from the vacuum chamber back into the ladle, thus performing a circulating vacuum degassing process.

[0003] The lining of the RH insert tube is made of refractory material. In the later stages of use, it is necessary to repair the refractory lining damaged by high-temperature molten steel erosion, slag corrosion, and thermal shock by spraying appropriate repair materials, thereby extending the service life of the insert tube. This requires the RH repair material to have excellent adhesion and good slag resistance. In some cases, the service life of the RH repair material is required to be no less than 3 heats.

[0004] However, based on actual on-site tracking statistics, the RH spraying material currently in use has revealed some technical problems that urgently need to be solved: First, the proportion of powder in the spraying material is too high, while the coarse aggregate is relatively insufficient. Such a ratio can easily lead to clogging of the spray gun. Second, the bonding strength of the spraying material is poor, and it is easy for material to fall off during spraying. This not only causes excessive consumption of the spraying material, but also affects work efficiency. Third, the slag resistance of the spraying material is insufficient. After processing molten steel, it is difficult to resist slag erosion, resulting in its actual service life not meeting the expected standard.

[0005] Therefore, researching an RH spraying compound that can combine good adhesion and good slag resistance has become an important technical challenge that urgently needs to be overcome. Summary of the Invention

[0006] The main objective of this invention is to provide a spraying material for RH insertion tubes, its composition, and preparation method, in order to solve the technical problem of how to improve the adhesion and anti-slag properties of the spraying material.

[0007] According to one aspect of the invention, a spraying material composition for RH insertion tubes is provided, comprising dry material and water, wherein the dry material comprises, by mass percentage: 30-40% recycled magnesia brick waste with a particle size of 0-3 mm and an MgO content of 82-87%, 30-40% sintered magnesia with a particle size of 0-3 mm, 20-25% medium-grade magnesia with a particle size less than 0.088 mm, 1-5% silica fume, and 2-6% binder; the water is 15-21% of the mass of the dry material.

[0008] According to one embodiment of the present invention, the recycled waste magnesium brick material comprises, by mass percentage: SiO2: 2.40-2.70%; Al2O3: 7.00-8.00%; Fe2O3: 1.00-2.00%; CaO: 1.60-2.00%; MgO: 82.00-87.00%.

[0009] According to one embodiment of the present invention, the sintered magnesia comprises, by mass percentage: SiO2: 3.00-6.00%; Al2O3: 1.00-1.50%; Fe2O3: 0.64-1.03%; CaO: 1.20-2.30%; MgO: 88.00-92.00%.

[0010] According to one embodiment of the present invention, the medium-grade magnesia comprises, by mass percentage: SiO2: 1.40-1.80%; Al2O3: 0.16-0.50%; Fe2O3: 0.90-1.40%; CaO: 1.60-2.00%; MgO: 94.50-95.50%.

[0011] According to one embodiment of the present invention, the silica fume comprises, by mass percentage: SiO2: 93.23-93.68%; Al2O3: 0.25-0.32%; Fe2O3: 0.04-0.07%; CaO: 0.59-0.81%; MgO: 2.49-2.63%.

[0012] According to one embodiment of the present invention, the binder comprises sodium hexametaphosphate, wherein the total phosphorus content in the sodium hexametaphosphate is 67.00-69.00% based on P2O5.

[0013] According to one embodiment of the present invention, the composition comprises, by mass percentage, 0-30% of recycled waste magnesium bricks with a particle size of 1-3 mm and 0-40% of recycled waste magnesium bricks with a particle size of 0-1 mm.

[0014] According to one embodiment of the present invention, the composition comprises, by mass percentage, 0-30% sintered magnesia with a particle size of 1-3 mm and 0-40% sintered magnesia with a particle size of 0-1 mm.

[0015] According to another aspect of the present invention, a method for preparing spray material for RH insertion tubes is provided, comprising: Provide raw materials, which are the composition described above; After the dry materials are evenly mixed, water is added and stirred to obtain the spraying material.

[0016] According to another aspect of the present invention, a spraying material for RH insertion tubes is provided, which is prepared by the method described above.

[0017] This invention, through a specially designed formula, enhances the adhesion and slag resistance of sprayed mortar. The recycled magnesia brick material provides a high MgO skeleton, ensuring stable pre-fired structure, reducing formula costs, and improving basic slag resistance. Sintered magnesia supplements high-purity MgO, improving overall refractoriness and erosion resistance, resulting in a dense crystalline phase. Medium-grade magnesia fine powder fills pores, promoting sintering and increasing density and strength. The addition of silica fume creates a micro-powder effect, optimizing particle size distribution, improving fluidity and low-temperature adhesion strength, and generating a forsterite-reinforced structure at high temperatures. The binder provides room-temperature adhesion and demolding strength, controlling setting time. Water wets and disperses the material, activates the binder hydration reaction, and provides application fluidity. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 A flowchart illustrating a method for preparing spray material for an RH insertion tube according to an embodiment of the present invention is shown. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments of the present invention will be further described in detail below with reference to specific examples and the accompanying drawings.

[0021] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0022] It should be noted that all uses of "first" and "second" in the embodiments of the present invention are for the purpose of distinguishing two entities or parameters with the same name but different names. It is clear that "first" and "second" are only for the convenience of expression and should not be construed as limiting the embodiments of the present invention. Subsequent embodiments will not explain this in detail.

[0023] This invention proposes a spraying material composition for RH insertion tubes, comprising dry material and water, wherein the dry material comprises, by mass percentage: 30-40% of recycled magnesia brick material with a particle size of 0-3 mm and an MgO content of 82-87% (in some cases, recycled magnesia brick material with a magnesium oxide content of 82%-87% is collectively referred to as M82-constant solid magnesia crystal), 30-40% of sintered magnesia with a particle size of 0-3 mm, 20-25% of medium-grade magnesia with a particle size less than 0.088 mm (corresponding to 180 mesh), 1-5% of silica fume, and 2-6% of binder; the water is 15-21% of the mass of the dry material.

[0024] This invention employs the specially designed formula described above, in which recycled waste magnesia bricks provide a high MgO skeleton, ensuring stable pre-fired structure, reducing formula costs, and improving slag resistance; sintered magnesia supplements high-purity MgO, enhancing overall refractoriness and erosion resistance, resulting in a dense crystalline phase; medium-grade magnesia fine powder fills pores, promoting sintering and improving density and strength; the addition of silica fume generates a micro-powder effect, optimizing particle size distribution, improving fluidity and low-temperature bonding strength, and generating forsterite reinforcement at high temperatures; the binder provides room-temperature bonding and demolding strength, controlling setting time; water wets and disperses the material, activates the binder hydration reaction, and provides construction fluidity. In embodiments of the present invention, recycled waste magnesia bricks with a particle size of 0-3 mm and sintered magnesia with a particle size of 0-3 mm are used as coarse aggregates, while medium-grade magnesia with a particle size less than 0.088 mm and silica fume with a particle size in the micrometer range (e.g., between 0.1-0.3 μm) constitute fine powder. This application designs a suitable ratio of coarse aggregate to fine powder, which can reduce the problem of clogging of the spray gun. A binder is used to bind the particles together, ensuring that the sprayed material has sufficient strength during the initial drying and baking stages after spraying and does not fall off.

[0025] In embodiments of the present invention, the mass percentage content of the recycled waste magnesia brick material can be 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39%, or 40%; the mass percentage content of sintered magnesia can be 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39%, or 40%; the mass percentage content of medium-grade magnesia can be 20%, 21%, 22%, 23%, 24%, or 25%; the mass percentage content of silica fume can be 1%, 2%, 3%, 4%, or 5%; the mass percentage content of binder can be 2%, 3%, 4%, 5%, or 6%; and the mass of water can be 15%, 16%, 17%, 18%, 19%, 20%, or 21% of the dry material mass.

[0026] Table 1. Main components (wt%) of each material in the spray patch composition

[0027] Table 1 shows the main components of the spraying material composition in some embodiments of this application. Referring to Table 1, in some embodiments, the recycled magnesia brick material includes, by mass percentage: SiO2: 2.40-2.70%; Al2O3: 7.00-8.00%; Fe2O3: 1.00-2.00%; CaO: 1.60-2.00%; MgO: 82.00-87.00%. The recycled magnesia brick material can be waste magnesia bricks dismantled from industrial kilns, etc., which, after sorting, crushing, screening, etc., yield magnesia raw materials with a certain particle size distribution. The waste magnesia bricks can originate from the linings of high-temperature equipment in steel plants, cement kilns, glass kilns, copper-nickel smelters, etc. The waste magnesia bricks have undergone a long period of "pre-sintering" under high-temperature operating conditions, resulting in more complete development of periclase crystals, larger crystal particles, and higher bulk density. This pre-sintering process results in very small linear shrinkage after firing during secondary high-temperature treatment, exhibiting excellent volume stability and helping to reduce shrinkage and cracking of refractory products during use. Waste magnesia bricks also possess excellent erosion resistance; their dense microstructure better resists the penetration and erosion of molten slag. Furthermore, using recycled waste magnesia bricks is beneficial for cost savings and environmental protection. In some embodiments, the composition comprises, by weight percentage, 0-30% recycled waste magnesia brick material with a particle size of 1-3 mm and 0-40% recycled waste magnesia brick material with a particle size of 0-1 mm. That is, the recycled waste magnesia brick material in this application can be any one or a combination of recycled waste magnesia brick material with a particle size of 1-3 mm and recycled waste magnesia brick material with a particle size of 0-1 mm.

[0028] Referring to Table 1, in some embodiments, the sintered magnesia comprises, by mass percentage: SiO2: 3.00-6.00%; Al2O3: 1.00-1.50%; Fe2O3: 0.64-1.03%; CaO: 1.20-2.30%; MgO: 88.00-92.00%. In some embodiments, the composition comprises, by mass percentage, 0-30% of sintered magnesia with a particle size of 1-3 mm and 0-40% of sintered magnesia with a particle size of 0-1 mm, that is, the sintered magnesia in this application can be any one or a combination of sintered magnesia with a particle size of 1-3 mm and sintered magnesia with a particle size of 0-1 mm.

[0029] Referring to Table 1, in some embodiments, the medium-grade magnesia comprises, by mass percentage: SiO2: 1.40-1.80%; Al2O3: 0.16-0.50%; Fe2O3: 0.90-1.40%; CaO: 1.60-2.00%; MgO: 94.50-95.50%.

[0030] Referring to Table 1, in some embodiments, the silica fume comprises, by mass percentage: SiO2: 93.23-93.68%; Al2O3: 0.25-0.32%; Fe2O3: 0.04-0.07%; CaO: 0.59-0.81%; MgO: 2.49-2.63%.

[0031] In some embodiments, the binder may include sodium hexametaphosphate, with a total phosphorus content of 67.00-69.00% in terms of P2O5, as shown in Table 1.

[0032] Table 2: Performance Comparison of RH Spraying Material

[0033] Table 2 shows a performance comparison between the spray coating of this application prepared based on the above composition and the existing spray coating, mainly involving compressive strength and linear shrinkage rate after burning.

[0034] Compressive strength reflects the strength performance of sprayed materials under working conditions. High compressive strength indicates high-temperature structural strength and resistance to mechanical / erosion damage. The method for testing compressive strength is as follows: Prepare a standard sample of the sprayed material, hold it at a specific temperature for a certain time, and then immediately apply pressure at a specified rate on a material testing machine until it breaks. The maximum pressure value recorded at this point, divided by the cross-sectional area of ​​the sample, is the compressive strength at that temperature.

[0035] The linear shrinkage rate after firing is the irreversible change rate of the linear dimension (length) of a sprayed material sample after heating and holding at a specified temperature for a certain period of time, expressed as a percentage (%). The formula for calculating the linear shrinkage rate after firing is: Where ΔL is the linear shrinkage rate after firing, L0 is the original length of the sample before heating, and L1 is the length of the sample after heating and cooling to room temperature. A positive linear shrinkage rate after firing indicates expansion; a negative linear shrinkage rate after firing indicates shrinkage. The linear shrinkage rate after firing can characterize the dimensional stability and resistance to thermal stress cracking of the sprayed material under high-temperature conditions.

[0036] Table 2 shows the compressive strength and linear shrinkage rate after firing of the sprayed material after holding at 1350℃, 1500℃, and 1600℃ for 3 hours. As can be seen from Table 2, the compressive strength of the sprayed material of this application is significantly improved compared to existing sprayed materials, and the linear shrinkage rate after firing of the sprayed material of this application is closer to 0 compared to existing sprayed materials.

[0037] refer to Figure 1 According to another aspect of the present invention, a method for preparing spray material for RH insertion tubes is provided, comprising the following steps: S1, providing raw materials, wherein the raw materials are the composition described above; S2, after uniformly mixing the dry materials, add water and mix to obtain the spraying material; the mixing time can be 2-5 minutes.

[0038] According to another aspect of the present invention, a spraying material for RH insertion tubes is provided, which is prepared by the method described above.

[0039] The following description is based on specific embodiments.

[0040] Example 1 The spraying material composition comprises dry materials and water. The dry materials include: 30 wt% recycled magnesia brick waste with a particle size of 1-3 mm, 40 wt% sintered magnesia with a particle size of 0-1 mm, 23 wt% medium-grade magnesia with a particle size less than 0.088 mm, 3 wt% silica fume, and 4 wt% sodium hexametaphosphate; the water content is 18% of the dry materials. The main components of each material are shown in Table 3.

[0041] Preparation method: First, add 30wt% of recycled waste magnesia brick material with a particle size of 1-3mm and 40wt% of sintered magnesia sand with a particle size of 0-1mm. Add the remaining dry materials according to the ratio. Mix the above dry materials evenly and add water according to the ratio and mix for 3 minutes to obtain No. 1 RH spraying material.

[0042] Table 3. Main components (wt%) of each material in the spraying compound composition of Example 1

[0043] The compressive strength and linear shrinkage rate after firing of the No. 1 RH sprayed material were tested, and the test data are shown in Table 4.

[0044] Table 4 Performance characterization data of spraying material in Example 1

[0045] Example 2 The spraying material composition comprises dry materials and water. The dry materials include: 30 wt% recycled magnesia brick waste with a particle size of 0-1 mm, 40 wt% sintered magnesia with a particle size of 1-3 mm, 23 wt% medium-grade magnesia with a particle size less than 0.088 mm, 3 wt% silica fume, and 4 wt% sodium hexametaphosphate; the water content is 18% of the dry materials. The main components of each material are shown in Table 5.

[0046] Preparation method: First, add 30wt% of recycled waste magnesia brick material with a particle size of 0-1mm and 40wt% of sintered magnesia sand with a particle size of 1-3mm. Add the remaining dry materials according to the ratio. Mix the above dry materials evenly and add water according to the ratio and mix for 3 minutes to obtain 2#RH spraying material.

[0047] Table 5. Main components (wt%) of each material in the spraying compound composition of Example 2

[0048] The compressive strength and linear shrinkage rate after firing of the No. 2 RH sprayed material were tested, and the test data are shown in Table 6.

[0049] Table 6 Performance characterization data of spraying material in Example 2

[0050] Example 3 The spraying material composition comprises dry materials and water. The dry materials include: 30 wt% recycled magnesia bricks with a particle size of 1-3 mm, 10 wt% recycled magnesia bricks with a particle size of 0-1 mm, 30 wt% sintered magnesia with a particle size of 0-1 mm, 23 wt% medium-grade magnesia with a particle size less than 0.088 mm, 3 wt% silica fume, and 4 wt% sodium hexametaphosphate. The water content is 18% of the dry materials. The main components of each material are shown in Table 7.

[0051] Preparation method: First, add 30wt% of waste magnesium brick recycling material with a particle size of 1-3mm and 10wt% of waste magnesium brick recycling material with a particle size of 0-1mm. Add the remaining dry materials according to the ratio. Mix the above dry materials evenly and add water according to the ratio and mix for 3 minutes to obtain 3#RH spraying material.

[0052] Table 7. Main components (wt%) of each material in the spraying compound composition of Example 3

[0053] The compressive strength and linear shrinkage rate after firing of the No. 3 RH sprayed material were tested, and the test data are shown in Table 8.

[0054] Table 8 Performance characterization data of the spraying material in Example 3

[0055] Example 4 The spraying material composition comprises dry material and water. The dry material includes: 30 wt% recycled magnesia brick material with a particle size of 0-1 mm, 10 wt% recycled magnesia brick material with a particle size of 1-3 mm, 20 wt% sintered magnesia with a particle size of 1-3 mm, 10 wt% sintered magnesia with a particle size of 0-1 mm, 23 wt% medium-grade magnesia with a particle size less than 0.088 mm, 3 wt% silica fume, and 4 wt% sodium hexametaphosphate. The water content is 18% of the dry material content. The main components of each material are shown in Table 9.

[0056] Preparation method: First, add 30wt% of waste magnesium brick recycling material with a particle size of 0-1mm and 10wt% of waste magnesium brick recycling material with a particle size of 1-3mm. Add the remaining dry materials according to the ratio. Mix the above dry materials evenly and add water according to the ratio and mix for 3 minutes to obtain 4#RH spraying material.

[0057] Table 9. Main components (wt%) of each material in the spraying compound composition of Example 4

[0058] The compressive strength and linear shrinkage rate after firing of the 4#RH sprayed material were tested, and the test data are shown in Table 10.

[0059] Table 10 Performance characterization data of spraying material in Example 4

[0060] Example 5 The spraying material composition comprises dry materials and water. The dry materials include: 40 wt% recycled magnesia brick waste with a particle size of 0-1 mm, 30 wt% sintered magnesia with a particle size of 1-3 mm, 23 wt% medium-grade magnesia with a particle size less than 0.088 mm, 3 wt% silica fume, and 4 wt% sodium hexametaphosphate; the water content is 18% of the dry materials. The main components of each material are shown in Table 11.

[0061] Preparation method: First, add 40wt% of recycled waste magnesia brick material with a particle size of 0-1mm and 30wt% of sintered magnesia sand with a particle size of 1-3mm. Add the remaining dry materials according to the ratio. Mix the above dry materials evenly and add water according to the ratio and mix for 3 minutes to obtain 5#RH spraying material.

[0062] Table 11. Main components (wt%) of each material in the spraying compound composition of Example 5

[0063] The compressive strength and linear shrinkage rate after firing of the 5#RH sprayed material were tested, and the test data are shown in Table 12.

[0064] Table 12 Performance characterization data of sprayed materials in Example 5

[0065] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of the invention (including the claims) is limited to these examples. Within the framework of the invention, technical features of the above embodiments or different embodiments can be combined, and many other variations of the different aspects of the invention as described above exist, which are not provided in the details for the sake of brevity. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the invention should be included within the protection scope of the invention.

Claims

1. A spraying material composition for RH insertion tubes, characterized in that, The mixture comprises dry materials and water, wherein the dry materials, by mass percentage, include: 30-40% recycled magnesia brick waste with a particle size of 0-3 mm and an MgO content of 82-87%, 30-40% sintered magnesia with a particle size of 0-3 mm, 20-25% medium-grade magnesia with a particle size less than 0.088 mm, 1-5% silica fume, and 2-6% binder; the water constitutes 15-21% of the mass of the dry materials.

2. The composition according to claim 1, characterized in that, The recycled waste magnesium brick material comprises, by mass percentage: SiO2: 2.40-2.70%; Al2O3: 7.00-8.00%; Fe2O3: 1.00-2.00%; CaO: 1.60-2.00%; MgO: 82.00-87.00%.

3. The composition according to claim 1, characterized in that, The sintered magnesia comprises, by mass percentage: SiO2: 3.00-6.00%; Al2O3: 1.00-1.50%; Fe2O3: 0.64-1.03%; CaO: 1.20-2.30%; MgO: 88.00-92.00%.

4. The composition according to claim 1, characterized in that, The medium-grade magnesia comprises, by mass percentage: SiO2: 1.40-1.80%; Al2O3: 0.16-0.50%; Fe2O3: 0.90-1.40%; CaO: 1.60-2.00%; MgO: 94.50-95.50%.

5. The composition according to claim 1, characterized in that, The silica fume comprises, by mass percentage: SiO2: 93.23-93.68%; Al2O3: 0.25-0.32%; Fe2O3: 0.04-0.07%; CaO: 0.59-0.81%; MgO: 2.49-2.63%.

6. The composition according to claim 1, characterized in that, The binder includes sodium hexametaphosphate, and the total phosphorus content in the sodium hexametaphosphate is 67.00-69.00% based on P2O5.

7. The composition according to claim 1, characterized in that, The composition comprises, by mass percentage, 0-30% of the recycled waste magnesium brick material with a particle size of 1-3 mm and 0-40% of the recycled waste magnesium brick material with a particle size of 0-1 mm.

8. The composition according to claim 1, characterized in that, The composition comprises, by weight percentage, 0-30% of the sintered magnesia with a particle size of 1-3 mm and 0-40% of the sintered magnesia with a particle size of 0-1 mm.

9. A method for preparing a spray material for an RH insertion tube, characterized in that, include: Provide raw materials, wherein the raw materials are the composition according to any one of claims 1-8; After the dry materials are evenly mixed, water is added and stirred to obtain the spraying material.

10. A spraying compound for RH insertion tubes, characterized in that, It is prepared by the method described in claim 9.

Images