Regenerated magnesia wet gunning mix and preparation method thereof

Abstract

The invention relates to the technical field of refractory materials, in particular to a regenerated magnesia wet gunning mix and a preparation method thereof. The regenerated magnesia wet gunning mix is prepared from the following raw materials: 60-75 wt% of regenerated magnesia; 8 wt%-18 wt% of sintered magnesia fine powder; 9 wt%-14 wt% of a binding agent; 4 wt%-8 wt% of a functional additive; the sum of the dosages of all the components is 100%. The binding agent comprises a sol aqueous solution, a polyphosphate complexing agent and cement; the functional additive comprises an aqueous solution of a cationic polyacrylamide flocculant, a nano material and explosion-proof fibers. The comprehensive performance of the regenerated magnesia wet gunning mix provided by the invention is excellent.

Description

Technical Field

[0001] The present invention relates to the technical field of refractory materials, in particular to a regenerated magnesia wet-process gunning material and a preparation method thereof. Background Art

[0002] In the field of metallurgical furnace maintenance, wet gunning technology is the mainstream solution for hot repair and has a large global market size. Traditional magnesium gunning materials have two major industry pain points:

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

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

[0005] Traditional magnesia gunning materials primarily use natural magnesia, which is subject to significant resource consumption and high costs. Recycled magnesia (MgO content ≥90% by mass) from scrap magnesia bricks, however, contains small amounts of residual carbon and trace impurities, making it difficult to directly use in the high-temperature environments of thermal kilns. Furthermore, traditional magnesia gunning materials often use organic binders such as phenolic resin, which can volatilize at high temperatures and pollute the environment.

[0006] Existing technologies for magnesia gunning materials can be categorized into three types: ① pure phosphate-bonded systems; ② silica sol-magnesia composite systems; and ③ alumina sol-modified systems. All of these solutions experience significant performance degradation at temperatures exceeding 1600°C, and strength decreases by over 50% when the amount of recycled material exceeds 30%.

[0007] Patent application CN202010751690.X discloses a large-diameter rare earth barium copper oxide superconducting target and its preparation method. The target uses a phosphate-magnesium oxide composite system, employing aluminum dihydrogen phosphate as the primary binder and adding 5μm-grade fused magnesia aggregate. The curing temperature must be maintained at 120°C for 24 hours. Measured data indicates a flexural strength of 4.2 MPa at 1600°C, with a recycled material content of ≤25%. However, the target suffers from poor high-temperature volume stability (linear stability of +1.8% at 1800°C).

[0008] Ali Shanaghi et al. published an article in ScienceDirect in 2019 titled “Nano-mechanical properties of zirconia-alumina-benzotriazole nano-composite coating deposited on Al2O 24 by the sol-gel method》Study on the preparation of Al2O 24Phase, structure and morphology characteristics of zirconia-alumina-benzotriazole nanocomposite coating deposited on the substrate. The research team systematically evaluated the nanomechanical properties of the coating using nanoindentation and nanoscratch techniques. Notably, this study demonstrated that after compounding the nanoscale zirconia sol (about 20 nm) with alumina micropowder, the coating exhibited excellent mechanical performance stability in the medium temperature range (1200-1400℃). The defects are: high cost (300% higher than traditional solutions), and poor compatibility with recycled magnesia.

[0009] Patent application file 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, but the chromium-free waste brick contains a certain amount of AlN and Al3C4, and a certain amount of gas is easily produced after water, causing hot-state peeling, affecting the strength and thermal shock performance of the material, and this technology introduces aluminum sol, silicon sol and aluminum-silicon composite sol as the binding system, 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 has high required curing temperature, poor high-temperature volume stability, high cost, and 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 the following components:

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

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

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

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

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

[0018] the binder comprises a sol aqueous solution, a polyphosphate composite agent and cement;

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

[0020] Preferably, 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.

[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 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.

[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 includes 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 includes component a and sodium hexametaphosphate; the component a includes 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 complexing agent, and the cement is 3-8:2-5:2-3.

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

[0030] Preferably, the nanomaterials include nano alpha-Al2O3 powder, nano magnesium-aluminum spinel powder or silicon carbide nanowires.

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

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

[0033] (A) Activating the regenerated magnesia;

[0034] (B) Mixing the regenerated magnesia after step (A), sintered magnesia fine powder, polyphosphate composite agent, cement, nanomaterials 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 an aqueous solution of cationic polyacrylamide flocculant to obtain the regenerated magnesia wet gunning material.

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

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

[0039] The application provides a regenerated magnesia wet gunning material prepared from raw materials including 60 wt%-75 wt% of regenerated magnesia, 8 wt%-18 wt% of sintered magnesia fine powder, 9 wt%-14 wt% of 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, polyphosphate composite agent and cement; and the functional additives include an aqueous solution of cationic polyacrylamide flocculant, nanomaterials and explosion-proof fiber. The existing magnesia wet gunning material has a high required curing temperature, poor high-temperature volume stability, high cost and poor compatibility with regenerated magnesia. The application uses the microwave-activated regenerated magnesia to replace the traditional high-grade magnesia raw material, which can ensure that the use performance is not obviously reduced, and the use of the sol and phosphate composite binder can ensure the volume stability of the material at medium and high temperatures and improve the erosion resistance of the material. The comprehensive performance of the regenerated magnesia wet gunning material provided by the application is obviously improved. DETAILED DESCRIPTION

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

[0041] The present application provides a wet gunning material for regenerative magnesia, which is prepared from raw materials comprising:

[0042] regenerative magnesia 60 wt%~75 wt%;

[0043] sintered magnesia fine powder 8 wt%~18 wt%;

[0044] binder 9 wt%~14 wt%;

[0045] functional additive 4 wt%~8 wt%;

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

[0047] the binder comprises a sol aqueous solution, a polyphosphate complexing agent and cement;

[0048] the functional additive comprises an aqueous solution of cationic polyacrylamide flocculant, nanomaterial and anti-explosion fiber.

[0049] In some embodiments of the present application, the particle size distribution of the regenerative 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; 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 regenerative 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; 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 content of MgO in the sintered magnesia fine powder is ≥ 95% by mass 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 binding agent is a sol, a polyphosphate complexing agent and a 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 content of ZrO2 is 15% to 25% by mass, such as 20%. In the yttrium stabilized zirconia sol, the content of Y2O3 is 2 to 4 mol%, such as 3 mol%. In the zirconium-aluminum composite sol, the mass ratio of ZrO2 and Al2O3 is 5 to 9: 1 to 5, such as 7:3.

[0055] The aqueous sol solution is obtained by mixing the sol and water. The mass ratio of the sol and water is 60 to 70: 30 to 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 to 1.5: 0.5 to 1.5, such as 1:1. The mass ratio of the sodium pyrophosphate and sodium hexametaphosphate is 0.5 to 1.5: 1.5 to 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 aqueous sol solution, the polyphosphate complexing agent and the cement is 3 to 8: 2 to 5: 2 to 3, such as 3.5:4:2.5, 7.5:2:2.5, 4:4:2.

[0059] The content of the binding agent in the raw material 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, nanomaterials and anti-explosion fiber. The mass ratio of the aqueous solution of cationic polyacrylamide flocculant, nanomaterials 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 aqueous solution of sol 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 nanomaterials are 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, nanomaterials and anti-explosion fiber to obtain a mixture;

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

[0070] (D) stirring and mixing the mixture liquid, the aqueous solution of cationic polyacrylamide flocculant to obtain the 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 the regenerated magnesia comprises 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 comprises microwave heating at 450-550℃ first, 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. The microwave heating can remove the impurities and residual carbon between the magnesia grains in the regenerated magnesia more fully, and thus obtain a more pure regenerated magnesia raw material.

[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] Regarding the plasma activation: the plasma activation is performed under an argon atmosphere, the power for the plasma activation is 3-7 kW, such as 5 kW; the time for 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 in the regenerated magnesia (decarbonization rate >98% at 500℃), and the treatment at 850℃ can reduce the recrystallization activation energy of MgO by 27%. Compared with the plasma activation, the microwave treatment has a cost advantage (energy consumption is reduced by 40%).

[0081] Regarding step (B):

[0082] The regenerated magnesia treated in step (A), sintered magnesia fine powder, polyphosphate complexing agent, cement, nanomaterials and anti-explosion 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] Regarding step (C):

[0085] The mixture is stirred with an aqueous solution of sol 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] Regarding step (D):

[0088] The mixture liquid is stirred with an aqueous solution of cationic polyacrylamide flocculant to obtain a wet-mixing gunning material of regenerated magnesia.

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

[0090] Regarding the zirconium sol-phosphate synergistic effect:

[0091] Zirconium sol (ZrO2) can react with phosphate to form ZrP2O7 phase at 1000-1400℃, filling the gap 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 magnesia wet-mixing gunning material requires a high curing temperature, has poor volume stability at high temperature, is high in cost, and has poor compatibility with regenerated magnesia. The present application uses regenerated magnesia activated by microwaves to replace traditional high-grade magnesia raw materials, and ensures that the use performance is not significantly reduced. In addition, the binder prepared by combining zirconium sol and phosphate can ensure the volume stability of the material at medium and high temperatures, and can improve the erosion resistance of the material. The comprehensive performance of the wet-mixing gunning material of regenerated magnesia provided by the present application is obviously improved.

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

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

[0096] Example 1

[0097] The raw materials for preparing the wet gunning material of the regenerated magnesia include:

[0098] 70 wt% of the regenerated magnesia;

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

[0100] 9 wt% of the binder;

[0101] 6 wt% of the 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; and 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 a 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 a cationic polyacrylamide flocculating agent, nano α-Al2O3 micropowder, and an anti-explosion fiber (polypropylene fiber); the mass ratio of the aqueous solution of the cationic polyacrylamide flocculating agent, the nano α-Al2O3 micropowder, and the anti-explosion fiber is 0.1:3.7:0.2.

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

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

[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 of the regenerated magnesia at 850℃ for 2 h;

[0109] (2) stirring and mixing the regenerated magnesia, sintered magnesia fine powder, polyphosphate compound, calcium aluminate cement, nano α-Al2O3 micro powder and explosion-proof fiber obtained in step (1) for 3 min to obtain a mixture;

[0110] (3) stirring and mixing the mixture obtained in step (2) with a sol aqueous solution for 2 min to obtain a mixture liquid;

[0111] (4) stirring and mixing the mixture liquid obtained in step (3) and a cationic polyacrylamide flocculant aqueous solution for 5 min to obtain a regenerated magnesia wet gunning mixture.

[0112] Example 2

[0113] The raw materials for preparing the regenerated magnesia wet gunning mixture 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; and 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 in the raw materials of the gunning mixture is 35:17:13.

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

[0120] The binder 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; the mass content of ZrO2 in the zirconium sol being 20%), a polyphosphate compound (sodium tripolyphosphate and sodium hexametaphosphate, the mass ratio of the sodium tripolyphosphate and sodium hexametaphosphate being 1:1), and calcium aluminate cement; and the mass ratio of the zirconium sol aqueous solution, the polyphosphate compound, and the calcium aluminate cement is 7.5:2:2.5.

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

[0122] The method for preparing the regenerated magnesia wet gunning mixture is the same as in Example 1.

[0123] Example 3

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

[0125] 75 wt% of reclaimed magnesia;

[0126] 8 wt% of sintered magnesia fine powder;

[0127] 11.7 wt% of binder;

[0128] 5.3 wt% of functional additive;

[0129] The particle size distribution of the reclaimed 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. In the raw materials of the gunning mix, 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 40:20:15.

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

[0131] The binder 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, nano α-Al2O3 micropowder, and anti-explosion fiber is 0.1:5:0.2.

[0133] The method for preparing the reclaimed magnesia wet gunning mix is the same as in Example 1.

[0134] Example 4

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

[0136] 70 wt% of reclaimed magnesia;

[0137] 16 wt% of sintered magnesia fine powder;

[0138] 10 wt% of binder;

[0139] 4 wt% of functional additive;

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

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

[0142] The binding agent 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 4:4:2.

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

[0144] The preparation method of the wet gunning material of the regenerated magnesia is the same as that in Example 1.

[0145] Example 5

[0146] The difference from Example 1 is that:

[0147] 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.

[0148] 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 30:25:5:10.

[0149] Comparative Example 1

[0150] The difference from Example 4 is that:

[0151] The zirconium sol in the binding agent 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 rest of the components and the preparation method are the same as those in Example 1.

[0153] Comparative Example 2

[0154] The difference from Example 4 is that:

[0155] The zirconium sol in the binding agent is replaced by a nano silicon sol, and the solid content of SiO2 in the nano silicon sol is 32%.

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

[0157] Comparative Example 3

[0158] The difference from Example 4 is:

[0159] The zirconium sol in the binder is replaced by aluminum sol and silica sol, with a mass ratio of aluminum sol to silica sol of 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%; the viscosity of the binder at room temperature is 800 mPa·s.

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

[0161] The performance of the regenerated magnesia wet gunning materials prepared in Examples 1 to 5 and Comparative Examples 1 to 3 was tested. The test results are shown in Tables 1 and 2. The bulk density of the regenerated magnesia wet gunning materials was measured with reference to the standard YB / T 5200, the flexural strength was measured with reference to GB / T 3001, and the burst rate was measured with reference to YB / T 4117; the adhesion rate was determined according to the following formula well known to those skilled in the art:

[0162] Adhesion rate = .

[0163] Table 1 Performance test results of regenerated magnesia wet gunning material in Example

[0164]

[0165] Table 2 Performance test results of the regenerated magnesia wet gunning material of the comparative example

[0166]

[0167] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A regenerated magnesia wet gunning material, characterized in that: It is prepared from raw materials including the following components: Regenerated 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 binder includes a sol aqueous solution, a polyphosphate compound and cement; The functional additives include an aqueous solution of a cationic polyacrylamide flocculant, nanomaterials and explosion-proof fibers; The polyphosphate complex comprises component a and sodium hexametaphosphate; the component a comprises sodium tripolyphosphate or sodium pyrophosphate; The nanomaterial includes nano α-Al2O3 powder, nano magnesium aluminum spinel powder or silicon carbide nanowire; The explosion-proof fiber includes polypropylene fiber or polyvinyl alcohol fiber.

2. The regenerated magnesia wet gunning material according to claim 1, characterized in that The particle size distribution of the regenerated magnesia includes: particles smaller than 5 mm and larger than 3 mm, particles smaller than 3 mm and larger than 1 mm, and particles smaller than 1 mm and larger than 0.1 mm; The mass ratio of the particles smaller than 5 mm and larger than 3 mm, the particles smaller than 3 mm and larger than 1 mm, and the particles smaller than 1 mm and larger than 0.1 mm is 35-40:15-20:10-15.

3. The regenerated magnesia wet gunning material according to claim 1, characterized in that The particle size distribution of the regenerated magnesia includes: particles smaller than 5 mm and larger than 3 mm, particles smaller than 3 mm and larger than 1 mm, particles smaller than 1 mm and larger than 0.5 mm, and particles smaller than 0.5 mm and larger than 0.1 mm; The mass ratio of the particles smaller than 5 mm and larger than 3 mm, the particles smaller than 3 mm and larger than 1 mm, the particles smaller than 1 mm and larger than 0.5 mm, and the particles smaller than 0.5 mm and larger than 0.1 mm is 30-35:20-25:5-15:5-10.

4. The regenerated magnesia wet gunning material according to claim 1, characterized in that The mass content of MgO in the sintered magnesia fine powder is ≥95%, and the particle size is ≤0.045 mm.

5. The regenerated magnesia wet gunning material according to claim 1, characterized in that The sol includes zirconium sol, yttrium-stabilized zirconia sol or 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%; in the zirconium-aluminum composite sol, the mass ratio of ZrO2 to Al2O3 is 5~9:1~5.

6. The regenerated magnesia wet gunning material according to claim 1, characterized in that The mass ratio of the sodium tripolyphosphate to the sodium hexametaphosphate is 0.5-1.5:0.5-1.5; the mass ratio of the sodium pyrophosphate to the 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 aqueous solution, the polyphosphate composite agent and the cement is 3-8:2-5:2-3.

7. The regenerated magnesia wet gunning material according to claim 1, characterized in that The mass ratio of the aqueous solution of the cationic polyacrylamide flocculant, the nanomaterial and the explosion-proof fiber is 0.05-0.15:3-5:0.1-0.

3.

8. The method for preparing the regenerated magnesia wet gunning material according to any one of claims 1 to 7, comprising the following steps: (A) Activating the regenerated magnesia; (B) mixing the regenerated magnesia treated in step (A), sintered magnesia fine powder, polyphosphate composite, cement, nanomaterials and explosion-proof fibers to obtain a mixture; (C) stirring and mixing the mixed material with the sol aqueous solution to obtain a mixed material liquid; (D) stirring and mixing the mixed liquid and the aqueous solution of the cationic polyacrylamide flocculant to obtain a regenerated magnesia wet gunning material.

9. The preparation method according to claim 8, characterized in that The activation method includes: two-stage microwave heating, or fluidized bed pyrolysis followed by microwave heating, or plasma activation; The two-stage microwave heating comprises: firstly heating the regenerated magnesia at 450-550° C. by microwave heating, and then heating the regenerated magnesia at 800-900° C. by microwave heating.

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