A wet gunning material for regenerative magnesia and a method for preparing the same

Abstract

The application relates to the technical field of refractory materials, in particular to a regenerated magnesia wet gunning material and a preparation method thereof. The regenerated magnesia wet gunning material is prepared from raw materials including the following components: 60 wt%-75 wt% of regenerated magnesia, 8 wt%-18 wt% of sintered magnesia fine powder, 9 wt%-14 wt% of a binding agent, and 4 wt%-8 wt% of functional additives, wherein the sum of the amounts of the components is 100%; the binding agent includes a sol water solution, a polyphosphate composite agent and cement; and the functional additives include an aqueous solution of a cationic polyacrylamide flocculant, nanomaterials and anti-explosion fibers. The comprehensive performance of the regenerated magnesia wet gunning material is relatively excellent.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of refractory materials, and particularly relates to a regenerated magnesia wet gunning material and a preparation method thereof. BACKGROUND

[0002] In the field of maintenance of metallurgical industrial furnaces, wet gunning technology is a mainstream scheme for hot repair, and has a large market size in the world. Traditional magnesia gunning materials have two industry pain points:

[0003] 1) sintering performance and bonding strength are difficult to balance;

[0004] 2) the utilization rate of regenerated magnesia is generally less than 40%.

[0005] Traditional magnesia gunning materials mainly use natural magnesia, and have problems of large resource consumption and high cost. The regenerated magnesia (MgO mass content is greater than or equal to 90%) of waste magnesia bricks is difficult to be directly applied to the high-temperature environment of thermal furnaces due to containing a small amount of residual carbon and trace impurities. At the same time, the traditional magnesia gunning material uses organic binders such as phenolic resin, and has problems of high-temperature volatilization and environmental pollution.

[0006] Regarding the magnesia gunning material, the existing technical routes can be divided into three categories: ① pure phosphate binding system; ② silica sol-magnesia composite system; and ③ aluminum sol modified system. These technical solutions will all have obvious performance degradation at 1600℃ working conditions, and the strength will decrease by more than 50% when the addition amount of regenerated material is more than 30%.

[0007] Patent application file CN202010751690.X discloses a large-diameter rare earth barium copper oxide superconducting target material and a preparation method thereof, which relates to a phosphate-magnesia composite system, uses aluminum dihydrogen phosphate as a main binder, adds 5μm grade fused magnesia aggregate, and needs to maintain 120℃ / 24h for solidification temperature. The measured data shows that the 1600℃ flexural strength is 4.2MPa, and the addition amount of regenerated material is less than or equal to 25%. The defect is poor high-temperature volume stability (1800℃ linear change rate +1.8%).

[0008] In 2019, Ali Shanaghi et al. published an article titled "Nano-mechanical properties of zirconia-alumina-benzotriazole nano-composite coating deposited on Al 2024 by the sol-gel method" in ScienceDirect. The article studied the phase, structure, and morphology characteristics of zirconia-alumina-benzotriazole nano-composite coating deposited on Al 2024 substrate by sol-gel method. The research team used nanoindentation and nanoscratch techniques to systematically evaluate the nanomechanical properties of the coating. Notably, the study confirmed that after compounding the nanoscale zirconia sol (about 20 nm) with alumina micro powder, the coating exhibited excellent mechanical property stability in the medium temperature range (1200-1400℃). The drawbacks are: high cost (300% higher than traditional solutions), and poor compatibility with recycled magnesia.

[0009] Patent application CN202411731040.3 discloses a magnesia spinel hot-state wet-type gunning material, its preparation method and application. Although the chromium-free waste brick is used as aggregate, the chromium-free waste brick contains a certain amount of AlN and Al3C4, which can produce a certain amount of gas when water is encountered, causing hot-state peeling, affecting the strength and thermal shock performance of the material. Moreover, this technology introduces aluminum sol, silicon sol, and aluminum-silicon composite sol as the binding system, and the material itself cannot form a certain grid strength, and there is a certain degree of hot-state peeling.

[0010] In summary, the existing magnesia wet gunning material requires a high curing temperature, has poor high-temperature volume stability, is high in cost, and has poor compatibility with recycled magnesia. SUMMARY

[0011] Therefore, the technical problem to be solved by the present application is to provide a recycled magnesia wet gunning material and a preparation method thereof. The recycled magnesia wet gunning material provided by the present application has excellent comprehensive performance.

[0012] The present application provides a recycled magnesia wet gunning material, which is prepared from raw materials comprising:

[0013] recycled magnesia 60 wt% to 75 wt%;

[0014] sintered magnesia fine powder 8 wt% to 18 wt%;

[0015] binder 9 wt% to 14 wt%;

[0016] functional additive 4 wt% to 8 wt%;

[0017] The sum of the amounts of the components is 100%;

[0018] The binding agent comprises a sol water solution, a polyphosphate complexing agent and cement;

[0019] The functional additive comprises an aqueous solution of cationic polyacrylamide flocculant, nanomaterial and anti-explosive fiber.

[0020] Preferably, the particle size distribution of the regenerated magnesia comprises particles less than 5 mm and greater than or equal to 3 mm, particles less than 3 mm and greater than or equal to 1 mm, and particles less than 1 mm and greater than or equal to 0.1 mm.

[0021] The mass ratio of the particles less than 5 mm and greater than or equal to 3 mm, the particles less than 3 mm and greater than or equal to 1 mm, and the particles less than 1 mm and greater than or equal to 0.1 mm is 35-40:15-20:10-15.

[0022] Preferably, the particle size distribution of the regenerated magnesia comprises particles less than 5 mm and greater than or equal to 3 mm, particles less than 3 mm and greater than or equal to 1 mm, particles less than 1 mm and greater than or equal to 0.5 mm, and particles less than 0.5 mm and greater than or equal to 0.1 mm.

[0023] The mass ratio of the particles less than 5 mm and greater than or equal to 3 mm, the particles less than 3 mm and greater than or equal to 1 mm, the particles less than 1 mm and greater than or equal to 0.5 mm, and the particles less than 0.5 mm and greater than or equal to 0.1 mm is 30-35:20-25:5-15:5-10.

[0024] Preferably, in the sintered magnesia fine powder, the mass content of MgO is ≥95%, and the particle size is ≤0.045 mm.

[0025] Preferably, the sol comprises a zirconium sol, a yttrium-stabilized zirconia sol, or a zirconium-aluminum composite sol; in the zirconium sol, the mass content of ZrO2 is 15%-25%; in the yttrium-stabilized zirconia sol, the content of Y2O3 is 2-4 mol%; and in the zirconium-aluminum composite sol, the mass ratio of ZrO2 and Al2O3 is 5-9:1-5.

[0026] Preferably, the polyphosphate complexing agent comprises component a and sodium hexametaphosphate; the component a comprises sodium tripolyphosphate or sodium pyrophosphate; the mass ratio of the sodium tripolyphosphate and the sodium hexametaphosphate is 0.5-1.5:0.5-1.5; and the mass ratio of the sodium pyrophosphate and the sodium hexametaphosphate is 0.5-1.5:1.5-2.5.

[0027] The cement is selected from calcium aluminate cement or magnesium phosphate cement.

[0028] The mass ratio of the sol aqueous solution, the polyphosphate composite agent and the cement is 3-8:2-5:2-3.

[0029] Preferably, the mass ratio of the cationic polyacrylamide flocculant aqueous solution, the nanomaterial and the explosion-proof fiber is 0.05-0.15:3-5:0.1-0.3.

[0030] Preferably, the nanomaterial comprises nano α-Al2O3 micro powder, nano magnesium aluminate spinel powder or silicon carbide nanowire.

[0031] The explosion-proof fiber comprises polypropylene fiber or polyvinyl alcohol fiber.

[0032] The application further provides a preparation method of the regenerated magnesia wet gunning material.

[0033] (A) Activating the regenerated magnesia;

[0034] (B) Mixing the regenerated magnesia treated in step (A), sintered magnesia fine powder, a polyphosphate composite agent, cement, nanomaterial and explosion-proof fiber to obtain a mixture;

[0035] (C) Stirring and mixing the mixture with a sol aqueous solution to obtain a mixture liquid;

[0036] (D) Stirring and mixing the mixture liquid and a cationic polyacrylamide flocculant aqueous solution to obtain the regenerated magnesia wet gunning material.

[0037] Preferably, the activation method comprises two-stage microwave heating, or fluidized bed pyrolysis followed by microwave heating, or plasma activation.

[0038] The two-stage microwave heating comprises: first microwave heating the regenerated magnesia at 450-550 ℃, and then microwave heating the regenerated magnesia at 800-900 ℃.

[0039] The application provides a wet gunning material of regenerated magnesia, which is prepared from raw materials including the following components: 60 wt%-75 wt% of regenerated magnesia, 8 wt%-18 wt% of sintered magnesia powder, 9 wt%-14 wt% of a binder, and 4 wt%-8 wt% of functional additives, wherein the sum of the amounts of the components is 100%, the binder includes a sol aqueous solution, a polyphosphate composite agent and cement, and the functional additives include an aqueous solution of cationic polyacrylamide flocculants, nanomaterials and anti-explosion fibers. The existing wet gunning material of magnesia has a high required curing temperature, poor high-temperature volume stability, high cost and poor compatibility with regenerated magnesia. The application uses regenerated magnesia activated by microwaves to replace traditional high-grade magnesia raw materials, which can ensure that the use performance is not obviously reduced, and the use of the binder compounded by the sol and the phosphate can ensure the volume stability of the material at medium and high temperatures and improve the corrosion resistance of the material. The comprehensive performance of the wet gunning material of regenerated magnesia is obviously improved. DETAILED DESCRIPTION

[0040] The technical solutions of the application will be described clearly and completely below with reference to the embodiments of the application. Obviously, the described embodiments are only some of the embodiments of the application, but not all the embodiments. Based on the embodiments in the application, all the other embodiments obtained by those skilled in the art without creative efforts fall within the protection scope of the application.

[0041] The application provides a wet gunning material of regenerated magnesia, which is prepared from raw materials including the following components:

[0042] 60 wt%-75 wt% of regenerated magnesia;

[0043] 8 wt%-18 wt% of sintered magnesia powder;

[0044] 9 wt%-14 wt% of a binder;

[0045] 4 wt%-8 wt% of functional additives;

[0046] The sum of the amounts of the components is 100%;

[0047] The binder includes a sol aqueous solution, a polyphosphate composite agent and cement;

[0048] The functional additives include an aqueous solution of cationic polyacrylamide flocculants, nanomaterials and anti-explosion fibers.

[0049] In some embodiments of the present application, the particle size distribution of the regenerated magnesia includes: particles less than 5 mm and greater than or equal to 3 mm, particles less than 3 mm and greater than or equal to 1 mm, and particles less than 1 mm and greater than or equal to 0.1 mm; the mass ratio of the particles less than 5 mm and greater than or equal to 3 mm, the particles less than 3 mm and greater than or equal to 1 mm, and the particles less than 1 mm and greater than or equal to 0.1 mm is 35-40:15-20:10-15, such as 38:18:14, 35:17:13, 40:20:15.

[0050] In some embodiments of the present application, the particle size distribution of the regenerated magnesia includes: particles less than 5 mm and greater than or equal to 3 mm, particles less than 3 mm and greater than or equal to 1 mm, particles less than 1 mm and greater than or equal to 0.5 mm, and particles less than 0.5 mm and greater than or equal to 0.1 mm; the mass ratio of the particles less than 5 mm and greater than or equal to 3 mm, the particles less than 3 mm and greater than or equal to 1 mm, the particles less than 1 mm and greater than or equal to 0.5 mm, and the particles less than 0.5 mm and greater than or equal to 0.1 mm is 30-35:20-25:5-15:5-10, such as 30:25:5:10.

[0051] The content of the regenerated magnesia in the raw material is 70 wt%, 65 wt%, 75 wt%.

[0052] In some embodiments of the present application, the mass content of MgO in the sintered magnesia fine powder is ≥95%, and the particle size is ≤0.045 mm. The content of the sintered magnesia fine powder in the raw material is 15 wt%, 17 wt%, 8 wt%, 16 wt%.

[0053] In some embodiments of the present application, the binder is a sol, a polyphosphate complexing agent, and cement.

[0054] The sol is selected from a zirconium sol, a yttrium stabilized zirconia sol, or a zirconium-aluminum composite sol. In the zirconium sol, the mass content of ZrO2 is 15%-25%, such as 20%. In the yttrium stabilized zirconia sol, the content of Y2O3 is 2-4 mol%, such as 3 mol%. In the zirconium-aluminum composite sol, the mass ratio of ZrO2 and Al2O3 is 5-9:1-5, such as 7:3.

[0055] The aqueous solution of the sol is obtained by mixing the sol and water. The mass ratio of the sol and water is 60-70:30-40, such as 65:35.

[0056] The polyphosphate complexing agent is component a and sodium hexametaphosphate. The component a is selected from sodium tripolyphosphate or sodium pyrophosphate (Na4P2O7). The mass ratio of the sodium tripolyphosphate and sodium hexametaphosphate is 0.5~1.5:0.5~1.5, such as 1:1. The mass ratio of the sodium pyrophosphate and sodium hexametaphosphate is 0.5~1.5:1.5~2.5, such as 1:2.

[0057] The cement is selected from calcium aluminate cement or magnesium phosphate cement (MgO-Mg3(PO4)2 system).

[0058] The mass ratio of the sol aqueous solution, polyphosphate complexing agent and cement is 3~8:2~5:2~3, such as 3.5:4:2.5, 7.5:2:2.5, 4:4:2.

[0059] In the raw material, the content of the binder is 9 wt%, 14 wt%, 11.7 wt%, 10 wt%.

[0060] In some embodiments of the present application, the functional additive is an aqueous solution of cationic polyacrylamide flocculant, nanomaterial and anti-explosion fiber. The mass ratio of the aqueous solution of cationic polyacrylamide flocculant, nanomaterial and anti-explosion fiber is 0.05~0.15:0.5~8:0.05~0.3, such as 0.05~0.15:3~5:0.1~0.3, and specifically can be 0.1:3.7:0.2, 0.1:5:0.2, 0.15:3.6:0.25.

[0061] The aqueous solution of cationic polyacrylamide flocculant is obtained by mixing cationic polyacrylamide flocculant diluent and water. The mass ratio of the water to the water in the sol aqueous solution is 0.8~1.2:0.8~1.2, such as 1:1.

[0062] The mass concentration of the cationic polyacrylamide flocculant diluent is 0.3%~0.7%, such as 0.5%. The cationic polyacrylamide flocculant diluent is obtained by diluting cationic polyacrylamide flocculant with water.

[0063] The nanomaterial is selected from nano α-Al2O3 micro powder, nano magnesium aluminate spinel powder or silicon carbide nanowire.

[0064] The anti-explosion fiber is selected from polypropylene fiber (PP) or polyvinyl alcohol fiber (PVA).

[0065] In the raw material, the content of the functional additive is 6 wt%, 4 wt%, 5.3 wt%.

[0066] The present application also provides a preparation method of the regenerated magnesia wet gunning material described above, comprising the following steps:

[0067] (A) Activating the regenerated magnesia;

[0068] (B) Mixing the regenerated magnesia treated in step (A), sintered magnesia fine powder, polyphosphate composite agent, cement, nanomaterial and explosion-proof fiber to obtain a mixture;

[0069] (C) Stirring and mixing the mixture with a sol aqueous solution to obtain a mixture liquid;

[0070] (D) Stirring and mixing the mixture liquid with an aqueous solution of cationic polyacrylamide flocculant to obtain a regenerated magnesia wet gunning material.

[0071] Regarding step (A):

[0072] The regenerated magnesia is activated.

[0073] In some embodiments of the present application, the method for activating includes two-stage microwave heating, or fluidized bed pyrolysis followed by microwave heating, or plasma activation.

[0074] In some embodiments of the present application, the two-stage microwave heating of the regenerated magnesia includes first microwave heating at 450-550℃, and then microwave heating at 800-900℃.

[0075] In some embodiments of the present application, in the two-stage microwave heating, the temperature for the first microwave heating is 500℃. The time for the microwave heating at 450-550℃ is 0.5-1.5 h, such as 1 h.

[0076] In some embodiments of the present application, in the two-stage microwave heating, the temperature for the second microwave heating is 850℃. The time for the microwave heating at 450-550℃ is 1-3 h, such as 2 h.

[0077] The two-stage microwave heating of the regenerated magnesia in the present application can activate the regenerated magnesia. By using microwave heating, the impurities and residual carbon between the magnesia grains in the regenerated magnesia can be more fully removed, and thus a purer regenerated magnesia raw material can be obtained.

[0078] Regarding the fluidized bed pyrolysis followed by microwave heating: the fluidized bed pyrolysis is performed under a nitrogen atmosphere, the temperature for the fluidized bed pyrolysis is 550-650℃, such as 600℃; the time for the fluidized bed pyrolysis is 1-2 h, such as 1.5 h. The temperature for the microwave heating is 750-850℃, such as 800℃; the time for the microwave heating is 0.5-1.5 h, such as 1 h.

[0079] As to the plasma activation: the plasma activation is carried out under an argon atmosphere, the power of the plasma activation is 3-7 kW, such as 5 kW; the time of the plasma activation is 20-40 min, such as 30 min.

[0080] In the present application, the microwave activation can decompose CaCO3 and residual carbon (decarburization rate > 98% at 500℃) in the regenerated magnesia, and the treatment at 850℃ can reduce the recrystallization activation energy of MgO by 27%. Compared with plasma activation, microwave treatment has a cost advantage (energy consumption is reduced by 40%).

[0081] As to step (B):

[0082] The regenerated magnesia treated in step (A), sintered magnesia fine powder, polyphosphate complexing agent, cement, nanomaterials and explosion-proof fiber are mixed to obtain a mixture.

[0083] In some embodiments of the present application, the mixing is stirring mixing. The mixing time is 2-4 min, such as 3 min.

[0084] As to step (C):

[0085] The mixture is stirred and mixed with a sol aqueous solution to obtain a mixture liquid.

[0086] In some embodiments of the present application, the stirring mixing time is 1-3 min, such as 2 min.

[0087] As to step (D):

[0088] The mixture liquid and an aqueous solution of cationic polyacrylamide flocculant are stirred and mixed to obtain a regenerated magnesia wet gunning material.

[0089] In some embodiments of the present application, the stirring mixing time is 4-6 min, such as 5 min.

[0090] As to the synergistic effect of zirconium sol-phosphate:

[0091] Zirconium sol (ZrO2) can react with phosphate to form ZrP2O7 phase at 1000-1400℃, filling the gaps between magnesia particles (SEM shows that the porosity is reduced by 52%).

[0092] In the present application, the combination of sodium tripolyphosphate and sodium hexametaphosphate can form [PO4] 3- Network structure, and ion bonding with zirconium sol (FTIR detects 1040 cm -1 Characteristic peak).

[0093] The existing magnesium wet gunning material needs a high curing temperature, has poor high-temperature volume stability, is high in cost, and has poor compatibility with regenerated magnesia. The regenerated magnesia activated by microwaves is used to replace the traditional high-grade magnesia raw material, and the use performance is not obviously reduced. In addition, the binder combined with zirconium sol and phosphate can ensure the volume stability of the material at medium and high temperatures, and can improve the corrosion resistance of the material. The comprehensive performance of the regenerated magnesia wet gunning material is obviously improved.

[0094] The raw material source used in the present application is not particularly limited and can be generally commercially available.

[0095] In order to further illustrate the present application, the regenerated magnesia wet gunning material and the preparation method thereof provided by the present application are described in detail below, but it should not be understood as limiting the protection scope of the present application.

[0096] Example 1

[0097] The preparation raw material of the regenerated magnesia wet gunning material includes:

[0098] 70 wt% of regenerated magnesia;

[0099] 15 wt% of sintered magnesia fine powder;

[0100] 9 wt% of binder;

[0101] 6 wt% of functional additive;

[0102] The particle size distribution of the regenerated magnesia includes: particles less than 5 mm and greater than or equal to 3 mm, particles less than 3 mm and greater than or equal to 1 mm, and particles less than 1 mm and greater than or equal to 0.1 mm; the mass ratio of the particles less than 5 mm and greater than or equal to 3 mm, the particles less than 3 mm and greater than or equal to 1 mm, and the particles less than 1 mm and greater than or equal to 0.1 mm is 38:18:14.

[0103] In the sintered magnesia fine powder, the mass content of MgO is greater than or equal to 95%, and the particle size is less than or equal to 0.045 mm.

[0104] The binder is a zirconium sol aqueous solution (obtained by mixing zirconium sol and water, the mass ratio of the zirconium sol and water is 65:35; in the zirconium sol, the mass content of ZrO2 is 20%), a polyphosphate complexing agent (sodium tripolyphosphate and sodium hexametaphosphate, the mass ratio of the sodium tripolyphosphate and sodium hexametaphosphate is 1:1), and calcium aluminate cement; the mass ratio of the zirconium sol aqueous solution, the polyphosphate complexing agent, and the calcium aluminate cement is 3.5:4:2.5.

[0105] The functional additive is an aqueous solution of cationic polyacrylamide flocculant, nano α-Al2O3 micropowder and anti-explosive fiber (polypropylene fiber). The mass ratio of the aqueous solution of cationic polyacrylamide flocculant, nano α-Al2O3 micropowder and anti-explosive fiber is 0.1:3.7:0.2.

[0106] The aqueous solution of cationic polyacrylamide flocculant is obtained by mixing cationic polyacrylamide flocculant diluent and water. The mass ratio of water to water in the aqueous solution of zirconium sol is 1:1. The mass concentration of the cationic polyacrylamide flocculant diluent is 0.5%. The cationic polyacrylamide flocculant diluent is obtained by diluting cationic polyacrylamide flocculant with water.

[0107] A method for preparing a wet gunning material of regenerated magnesia:

[0108] (1) Two-stage microwave heating of the regenerated magnesia: first microwave heating of the regenerated magnesia at 500℃ for 1 h, and then microwave heating at 850℃ for 2 h;

[0109] (2) Stirring and mixing of the regenerated magnesia treated in step (1), sintered magnesia fine powder, polyphosphate composite agent, calcium aluminate cement, nano α-Al2O3 micropowder and anti-explosive fiber for 3 min to obtain a mixture;

[0110] (3) Stirring and mixing of the mixture with an aqueous sol solution for 2 min to obtain a mixture liquid;

[0111] (4) Stirring and mixing of the mixture liquid and the aqueous solution of cationic polyacrylamide flocculant for 5 min to obtain the wet gunning material of regenerated magnesia.

[0112] Example 2

[0113] The raw materials for preparing the wet gunning material of regenerated magnesia include:

[0114] Regenerated magnesia 65 wt%;

[0115] Sintered magnesia fine powder 17 wt%;

[0116] Binder 14 wt%;

[0117] Functional additive 4 wt%;

[0118] The particle size distribution of the regenerated magnesia includes particles smaller than 5 mm and equal to or larger than 3 mm, particles smaller than 3 mm and equal to or larger than 1 mm, and particles smaller than 1 mm and equal to or larger than 0.1 mm. In the raw materials of the gunning material, the mass ratio of the particles smaller than 5 mm and equal to or larger than 3 mm, the particles smaller than 3 mm and equal to or larger than 1 mm, and the particles smaller than 1 mm and equal to or larger than 0.1 mm is 35:17:13.

[0119] The sintered magnesia fine powder is the same as in Example 1.

[0120] The binding agent is a zirconium sol aqueous solution (obtained by mixing a zirconium sol and water, the mass ratio of the zirconium sol and water being 65:35; in the zirconium sol, the mass content of ZrO2 is 20%), a polyphosphate complexing agent (sodium tripolyphosphate and sodium hexametaphosphate, the mass ratio of the sodium tripolyphosphate and sodium hexametaphosphate being 1:1) and calcium aluminate cement; the mass ratio of the zirconium sol aqueous solution, the polyphosphate complexing agent and the calcium aluminate cement is 7.5:2:2.5.

[0121] The functional additive is the same as in Example 1.

[0122] The preparation method of the wet gunning magnesia-slag mixture is the same as in Example 1.

[0123] Example 3

[0124] The raw materials for preparing the wet gunning magnesia-slag mixture include:

[0125] Regenerated magnesia 75 wt%;

[0126] Sintered magnesia fine powder 8 wt%;

[0127] Binding agent 11.7 wt%;

[0128] Functional additive 5.3 wt%;

[0129] The particle size distribution of the regenerated magnesia includes particles smaller than 5 mm and equal to or larger than 3 mm, particles smaller than 3 mm and equal to or larger than 1 mm, and particles smaller than 1 mm and equal to or larger than 0.1 mm; in the raw materials for preparing the gunning mixture, the mass ratio of the particles smaller than 5 mm and equal to or larger than 3 mm, the particles smaller than 3 mm and equal to or larger than 1 mm, and the particles smaller than 1 mm and equal to or larger than 0.1 mm is 40:20:15.

[0130] The sintered magnesia fine powder is the same as in Example 1.

[0131] The binding agent is the same as in Example 1.

[0132] The functional additive is an aqueous solution of cationic polyacrylamide flocculant, nano α-Al2O3 micropowder and anti-explosion fiber (polypropylene fiber); the mass ratio of the aqueous solution of cationic polyacrylamide flocculant, the nano α-Al2O3 micropowder and the anti-explosion fiber is 0.1:5:0.2.

[0133] The preparation method of the wet gunning magnesia-slag mixture is the same as in Example 1.

[0134] Example 4

[0135] The raw materials for preparing the wet gunning mix of the reclaimed magnesia include:

[0136] Reclaimed magnesia 70 wt%;

[0137] Sintered magnesia fine powder 16 wt%;

[0138] Binder 10 wt%;

[0139] Functional additive 4 wt%;

[0140] The particle size distribution of the reclaimed magnesia is the same as that of Example 1.

[0141] The sintered magnesia fine powder is the same as that of Example 1.

[0142] The binder is a zirconium sol aqueous solution (obtained by mixing a zirconium sol and water, the mass ratio of the zirconium sol to water being 65:35; in the zirconium sol, the mass content of ZrO2 is 20%), a polyphosphate complexing agent (sodium tripolyphosphate and sodium hexametaphosphate, the mass ratio of the sodium tripolyphosphate to the sodium hexametaphosphate being 1:1), and calcium aluminate cement; the mass ratio of the zirconium sol aqueous solution, the polyphosphate complexing agent, and the calcium aluminate cement is 4:4:2.

[0143] The functional additive is an aqueous solution of cationic polyacrylamide flocculant, nano α-Al2O3 micro powder, and anti-explosion fiber (polypropylene fiber); the mass ratio of the aqueous solution of cationic polyacrylamide flocculant, the nano α-Al2O3 micro powder, and the anti-explosion fiber is 0.15:3.6:0.25.

[0144] The method for preparing the wet gunning mix of the reclaimed magnesia is the same as that of Example 1.

[0145] Example 5

[0146] The difference from Example 1 is that:

[0147] The particle size distribution of the reclaimed magnesia includes particles smaller than 5 mm and equal to or greater than 3 mm, particles smaller than 3 mm and equal to or greater than 1 mm, particles smaller than 1 mm and equal to or greater than 0.5 mm, and particles smaller than 0.5 mm and equal to or greater than 0.1 mm.

[0148] The mass ratio of the particles smaller than 5 mm and equal to or greater than 3 mm, the particles smaller than 3 mm and equal to or greater than 1 mm, the particles smaller than 1 mm and equal to or greater than 0.5 mm, and the particles smaller than 0.5 mm and equal to or greater than 0.1 mm is 30:25:5:10.

[0149] Comparative Example 1

[0150] The difference from Example 4 is that:

[0151] The zirconium sol in the binder is replaced by an aluminum sol (specifically, a nano-alumina sol), and the solid content of Al2O3 in the aluminum sol is 25%.

[0152] The remaining components and the preparation method are the same as in Example 1.

[0153] Comparative Example 2

[0154] The difference from Example 4 is that:

[0155] The zirconium sol in the binder is replaced by a nano-silica sol, and the solid content of SiO2 in the nano-silica sol is 32%.

[0156] The remaining components and the preparation method are the same as in Example 1.

[0157] Comparative Example 3

[0158] The difference from Example 4 is that:

[0159] The zirconium sol in the binder is replaced by an aluminum sol and a silica sol, and the mass ratio of the aluminum sol to the silica sol is 3:2; the aluminum sol is a nano-alumina sol, and the solid content of Al2O3 in the aluminum sol is 25%; the silica sol is a nano-silica sol, and the solid content of SiO2 in the silica sol is 32%; and the viscosity of the binder at room temperature is 800 mPa·s.

[0160] The remaining components and the preparation method are the same as in Example 1.

[0161] The properties of the wet gunning material of the regenerated magnesia prepared in Examples 1-5 and Comparative Examples 1-3 are detected, and the detection results are shown in Tables 1 and 2. The bulk density of the wet gunning material of the regenerated magnesia is measured according to the standard YB / T 5200, the modulus of rupture is measured according to GB / T 3001, and the bursting rate is measured according to YB / T 4117. The adhesion rate is determined according to the following formula well known to those skilled in the art:

[0162] Adhesion rate = (Wet gunning material weight after drying) / (Wet gunning material weight before drying) × 100% .

[0163] Table 1: Performance detection results of the wet gunning material of the regenerated magnesia of the examples

[0164]

[0165] Table 2: Performance detection results of the wet gunning material of the regenerated magnesia of the comparative examples

[0166]

[0167] The foregoing description of the disclosed embodiments enables a person skilled in the art to make or use the application. Modifications of these embodiments will occur to persons of skill in the art, and that the appended claims are intended to cover all such modifications that do not depart from the true spirit and scope of the application. Therefore, the application is not limited to the embodiments shown but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A recycled magnesia wet spraying compound, characterized in that, It is prepared from raw materials comprising the following components: Recycled magnesia 60 wt%~75 wt%; Sintered magnesia fine powder 8 wt%~18 wt%; Binder 9 wt%~14 wt%; Functional additives 4 wt%~8 wt%; The sum of the amounts of the components is 100%; The recycled magnesia is microwave activated before the raw materials are mixed. The binder comprises a sol-water solution, a polyphosphate composite agent, and cement; the sol is a zirconium sol. The functional additives include an aqueous solution of cationic polyacrylamide flocculant, nanomaterials, and explosion-proof fibers. The polyphosphate composite agent includes component a and sodium hexametaphosphate; component a includes sodium tripolyphosphate or sodium pyrophosphate. The nanomaterials include nano-α-Al2O3 micro powder, nano-magnesium aluminum spinel powder, or silicon carbide nanowires. The explosion-proof fiber includes polypropylene fiber or polyvinyl alcohol fiber.

2. The recycled magnesia wet spraying material according to claim 1, characterized in that, The particle size distribution of the recycled magnesia includes: particles smaller than 5 mm and greater than or equal to 3 mm, particles smaller than 3 mm and greater than or equal to 1 mm, and particles smaller than 1 mm and greater than or equal to 0.1 mm. The mass ratio of particles smaller than 5 mm and greater than or equal to 3 mm, particles smaller than 3 mm and greater than or equal to 1 mm, and particles smaller than 1 mm and greater than or equal to 0.1 mm is 35~40:15~20:10~15.

3. The recycled magnesia wet spraying material according to claim 1, characterized in that, The particle size distribution of the recycled magnesia includes: particles smaller than 5 mm and greater than or equal to 3 mm, particles smaller than 3 mm and greater than or equal to 1 mm, particles smaller than 1 mm and greater than or equal to 0.5 mm, and particles smaller than 0.5 mm and greater than or equal to 0.1 mm. The mass ratio of particles smaller than 5 mm and greater than or equal to 3 mm, particles smaller than 3 mm and greater than or equal to 1 mm, particles smaller than 1 mm and greater than or equal to 0.5 mm, and particles smaller than 0.5 mm and greater than or equal to 0.1 mm is 30~35:20~25:5~15:5~10.

4. The recycled magnesia wet spraying material according to claim 1, characterized in that, The sintered magnesia fine powder contains ≥95% MgO by mass and has a particle size ≤0.045 mm.

5. The recycled magnesia wet spraying material according to claim 1, characterized in that, The zirconium sol contains 15% to 25% ZrO2 by mass.

6. The recycled magnesia wet spraying material according to claim 1, characterized in that, The mass ratio of sodium tripolyphosphate to sodium hexametaphosphate is 0.5~1.5:0.5~1.5; the mass ratio of sodium pyrophosphate to sodium hexametaphosphate is 0.5~1.5:1.5~2.

5. The cement is selected from calcium aluminate cement or magnesium phosphate cement. The mass ratio of the sol-sol solution, polyphosphate composite agent, and cement is 3~8:2~5:2~3.

7. The recycled magnesia wet spraying material according to claim 1, characterized in that, The mass ratio of the cationic polyacrylamide flocculant aqueous solution, nanomaterials, and explosion-proof fibers is 0.05~0.15:3~5:0.1~0.

3.

8. A method for preparing the recycled magnesia wet spraying material according to any one of claims 1 to 7, comprising the following steps: (A) Microwave activation of recycled magnesia; (B) The recycled magnesia, sintered magnesia fine powder, polyphosphate composite agent, cement, nanomaterials and explosion-proof fiber after step (A) are mixed to obtain a mixture; (C) The mixture is stirred and mixed with the sol-water solution to obtain a mixed liquid; (D) The mixture and the aqueous solution of cationic polyacrylamide flocculant are stirred and mixed to obtain recycled magnesium sand wet spraying material.

9. The preparation method according to claim 8, characterized in that, The microwave activation method is: two-stage microwave heating; The two-stage microwave heating process includes: first, microwave heating the recycled magnesia at 450~550℃, and then microwave heating it at 800~900℃.

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