Corundum coating and preparation method thereof

Abstract

The invention discloses a corundum coating and a preparation method thereof. The coating material is prepared from aggregate, powder, an additive and a binding agent, in addition, an additive is added; the aggregate is composed of waste corundum mullite bricks smaller than or equal to 3 mm, regenerated corundum and regenerated fused corundum, and the powder is composed of waste corundum mullite bricks smaller than or equal to 0.037 mm, regenerated corundum smaller than or equal to 0.074 mm, regenerated fused corundum smaller than or equal to 0.074 mm and alpha alumina micro powder smaller than or equal to 0.045 mm; the additive is composed of silica powder, nanometer silica powder, bentonite and mullite whiskers, the binding agent is composed of sodium tripolyphosphate, sodium hexametaphosphate, industrial glucose, carboxymethyl cellulose and solid water glass, and the admixture is explosion-proof fibers formed by mixing polyethylene, polypropylene and polyester fibers. The raw materials are mixed, then water is added for continuous stirring, and after the obtained coating is in a paste shape, the coating is discharged for standby application. The corundum coating disclosed by the invention can form good bonding strength with bricks at low temperature and high temperature, is good in erosion resistance and thermal shock resistance, and can completely meet the construction and operation requirements of high-temperature kilns.

Description

1. Technical field:

[0001] The invention belongs to the technical field of refractory material production, and in particular relates to a corundum coating material for a nickel-vanadium alloy reaction furnace and a preparation method thereof. 2. Background technology:

[0002] High-temperature kilns for non-ferrous metal smelting, such as reactors for nickel-vanadium alloy smelting, mostly use corundum bricks with good corrosion resistance as working linings. During the brick laying process, since the furnace structure of the reactor is cylindrical and the bricks are wedge-shaped, the hot surface of the bricks in contact with the alloy melt will be uneven after laying. Generally, coating materials are used to apply them, thereby forming a relatively smooth inner wall of the kiln lining. On the one hand, the coating material fills the unevenness formed on the brick surface and the gaps between bricks in the kiln, plays the role of "leveling" the inner wall surface, and makes the pouring of the alloy melt smoother; on the other hand, the coating material forms a bonding strength with the bricks outward during the smelting process, and forms a reaction protective layer with the alloy melt inward, preventing the melt from leaking outward and eroding, thereby increasing the service life of the kiln lining. Therefore, the coating material has a great impact on the smelting efficiency and safety of nickel-vanadium alloys.

[0003] The long-term use of non-ferrous metal smelting and glass high-temperature kilns that use corundum bricks as working linings has produced a large amount of used bricks, which have been accumulated over the years to form solid waste. Conventional corundum coatings have low high-temperature bonding strength and insufficient thermal shock resistance. When the high-temperature melt is poured out of the electric arc furnace, the coating is prone to cracking and flaking. Mixing into the alloy not only has a great impact on the production efficiency and quality of the nickel-vanadium alloy, but the flaking of the coating layer will also cause the melt to penetrate into the brick layer, accelerating the erosion of the bricks, thereby greatly reducing the service life of the kiln. 3. Summary of the invention:

[0004] The technical problem to be solved by the present invention is: in view of the technical problems that the existing corundum coating has low high-temperature bonding strength, insufficient thermal shock resistance, and the coating is prone to cracking and block peeling when the high-temperature melt is poured out from the electric arc furnace, the present invention provides a new corundum coating and a preparation method thereof. The present invention uses waste corundum mullite waste bricks, recycled corundum and recycled fused corundum as the main raw materials, adds a proper amount of water during construction, can form good bonding strength with bricks at both low and high temperatures, and has good corrosion resistance and thermal shock resistance, which can fully meet the construction and operation requirements of high-temperature kilns.

[0005] In order to solve the above problems, the technical solution adopted by the present invention is:

[0006] The present invention provides a corundum-based coating material. In terms of mass percentage, the corundum-based coating material mainly consists of 57 - 67% of aggregate, 22 - 32% of powder, 5 - 12% of additive, and 1 - 4% of binder; in addition, an admixture accounting for 0.1 - 1% of the total weight of various raw materials is added.

[0007] The 57 - 67% of the aggregate consists of 15 - 22% of waste corundum-mullite bricks with a particle size ≤ 3 mm, 20 - 26% of recycled corundum with a particle size ≤ 3 mm, and 16 - 23% of recycled fused corundum with a particle size ≤ 3 mm.

[0008] The 22 - 32% of the powder consists of 12 - 19% of waste corundum-mullite bricks with a particle size ≤ 0.037 mm, 5 - 12% of recycled corundum with a particle size ≤ 0.074 mm, 2 - 7% of recycled fused corundum with a particle size ≤ 0.074 mm, and 1 - 3% of α-aluminum oxide micropowder with a particle size ≤ 0.045 mm.

[0009] For the corundum-based coating material described above, the waste corundum-mullite bricks have an Al₂O₃ content ≥ 78% and a SiO₂ content ≤ 25%; the waste corundum-mullite bricks are directly crushed into the corresponding particle sizes from the recycled corundum-mullite bricks after use.

[0010] For the corundum-based coating material described above, the recycled corundum has an Al₂O₃ content ≥ 80%, a TiO₂ content ≤ 2.5%, an Fe₂O₃ content ≤ 1.5%, and a CaO content ≤ 3%.

[0011] The recycled corundum is obtained by classifying and sorting the used corundum refractory bricks, removing the working layer, crushing, soaking and cleaning, drying, cooling, and secondary crushing, and finally screening into different required particle sizes.

[0012] For the corundum-based coating material described above, the recycled fused corundum has an Al₂O₃ content ≥ 85%, an Fe₂O₃ content ≤ 1.0%, and a CaO content ≤ 1.0%.

[0013] The recycled fused corundum is obtained by classifying and sorting the used fused corundum refractory bricks, removing the working layer, crushing, soaking and cleaning, drying, cooling, and secondary crushing, and finally screening into different required particle sizes.

[0014] For the corundum-based coating material described above, the additive consists of silica fume, nano-silica fume, bentonite, and mullite whiskers; the mass ratio among the silica fume, nano-silica fume, bentonite, and mullite whiskers is 1 - 2:1 - 2:1 - 3:1 - 2.

[0015] According to the above-mentioned corundum-based coating material, the binder is composed of sodium tripolyphosphate, sodium hexametaphosphate, industrial glucose, carboxymethyl cellulose, and solid water glass; the mass ratio among sodium tripolyphosphate, sodium hexametaphosphate, industrial glucose, carboxymethyl cellulose, and solid water glass is 4-6:4-6:8-10:3-5:5-7.

[0016] According to the above-mentioned corundum-based coating material, the admixture is an explosion-proof fiber composed of polyethylene, polypropylene, and polyester fiber.

[0017] In addition, a preparation method of the corundum-based coating material is provided. The preparation method includes the following steps:

[0018] a. Weigh various raw materials according to the mixing ratio of the above-mentioned corundum-based coating material;

[0019] b. Place the weighed aggregate, powder, additive, binder, and admixture in a forced mixer for stirring and mixing. Stir and mix for 5-10 minutes, then add tap water accounting for 5-10% of the total weight of all raw materials and continue to stir forcibly for 5-8 minutes. Wait until the obtained coating material becomes a mud paste and discharge it for standby.

[0020] The positive and beneficial effects of the present invention:

[0021] 1. The corundum-based coating material prepared by adopting the technical scheme of the present invention can effectively improve the high-temperature bonding strength of the coating material, prevent blocky shedding, and has good erosion resistance, protect refractory bricks, and extend the service life of the kiln.

[0022] 2. The technical scheme of the present invention uses waste corundum-mullite bricks, recycled corundum, and recycled fused corundum as the main raw materials, realizes the recycling of waste resources, turns waste into treasure, reduces resource consumption and carbon emissions in the raw material preparation process, reduces environmental pollution, and is beneficial to environmental protection.

[0023] 3. Using the present invention to prepare the corundum-based coating material reduces the production cost, improves the economic benefits of the enterprise, and has a broad market application prospect.

[0024] 4. It can be proved by the test results of the corundum-based coating material prepared in the examples (the flexural strength in the test reflects the bonding performance at different temperatures, and the greater the strength, the stronger the bonding between the coating layer and the brick; at low temperatures such as 110°C and 600°C, the strengths are close, mainly relying on the bonding effect of the adhesive; the strength at high temperatures is improved because the coating material of the present invention and the brick form good sintering strength at high temperatures). The improvement in performance of the corundum-based coating material prepared by the present invention is mainly reflected in the obvious improvement in the bonding strength between the coating material and the brick at high temperatures, avoiding physical peeling that may occur in the coating layer during the melt scouring.

[0025] In summary, the present invention has significant economic and social benefits. IV. Specific Embodiments:

[0026] The present invention will be further described below in conjunction with embodiments, but does not limit the scope of protection of the technical solution of the present invention.

[0027] In the following embodiments, the used corundum-mullite bricks adopted have an Al2O3 content ≥ 78% and SiO2 ≤ 25%; the recycled corundum has an Al2O3 content ≥ 80%, TiO2 ≤ 2.5%, Fe2O3 ≤ 1.5%, and CaO ≤ 3%; the recycled fused corundum has an Al2O3 content ≥ 85%, Fe2O3 ≤ 1.0%, and CaO ≤ 1.0%.

[0028] The used corundum-mullite bricks are directly crushed into the corresponding required particle sizes, namely particle size ≤ 3 mm and particle size ≤ 0.037 mm, from the recycled corundum-mullite bricks.

[0029] The recycled corundum is obtained by classifying and sorting the used corundum refractory bricks, removing the working layer, crushing, soaking and cleaning, drying, cooling, and secondary crushing, and finally screening into different required particle sizes; namely particle size ≤ 3 mm and particle size ≤ 0.074 mm.

[0030] The recycled fused corundum is obtained by classifying and sorting the used fused corundum refractory bricks, removing the working layer, crushing, soaking and cleaning, drying, cooling, and secondary crushing, and finally screening into different required particle sizes; namely particle size ≤ 3 mm and particle size ≤ 0.074 mm.

[0031] Example 1:

[0032] The corundum-based coating material of the present invention, expressed in mass percentage, is composed of 57% aggregate, 32% powder, 8% additive, and 3% binder; in addition, an admixture accounting for 0.15% of the total weight of various raw materials is added;

[0033] The 57% aggregate is composed of 15% used corundum-mullite bricks with particle size ≤ 3 mm, 26% recycled corundum with particle size ≤ 3 mm, and 16% recycled fused corundum with particle size ≤ 3 mm;

[0034] The 32% powder is composed of 15% used corundum-mullite bricks with particle size ≤ 0.037 mm, 12% recycled corundum with particle size ≤ 0.074 mm, 3% recycled fused corundum with particle size ≤ 0.074 mm, and 2% α-aluminum oxide micropowder with particle size ≤ 0.045 mm.

[0035] The 8% additive is composed of 1% silica fume, 2% nano-silica fume, 3% bentonite, and 2% mullite whiskers;

[0036] The binder of 3% is composed of 0.5% of sodium tripolyphosphate, 0.5% of sodium hexametaphosphate, 1% of industrial glucose, 0.3% of carboxymethyl cellulose and 0.7% of solid water glass;

[0037] The admixture is an explosion-proof fiber made of a mixture of polyethylene, polypropylene and polyester fiber.

[0038] The preparation method of the corundum-based daub described in Example 1 of the present invention is as follows in detail:

[0039] a. Weigh various raw materials according to the proportion of the corundum-based daub described in Example 1, and pre-mix various raw materials;

[0040] b. Then place them in a forced mixer for stirring and mixing for 8 minutes, then add tap water accounting for 6% of the total weight of all raw materials and continue forced stirring for 8 minutes. Wait until the obtained daub becomes a mud paste and discharge it for standby.

[0041] After the corundum-based daub prepared in this example is subjected to construction operations, samples of the daub are taken for testing: the bulk density after drying at 110°C for 24 hours is 60 g / cm 3 , the bulk density after heat treatment at 600°C for 3 hours is 2.67 g / cm 3 , the bulk density after heat treatment at 1200°C for 3 hours is 2.81 g / cm 3 ; the bulk density after heat treatment at 1400°C for 3 hours is 2.89 g / cm 3 .

[0042] Cut the corundum brick into 40×40×60 mm specimens, use the daub prepared in this example to bond the brick specimens, and perform the flexural strength of the bonded specimens after heat treatment at the corresponding temperature. The flexural strength after drying at 110°C for 24 hours is 2.5 MPa; the flexural strength after heat treatment at 600°C for 3 hours is 2.1 MPa; the flexural strength after heat treatment at 1200°C for 3 hours is 4.1 MPa; the flexural strength after heat treatment at 1400°C for 3 hours is 5.3 MPa.

[0043] Example 2:

[0044] The corundum-based daub of the present invention, expressed in mass percentage, is composed of 58% of aggregate, 32% of powder, 7% of additive and 3% of binder; in addition, an admixture accounting for 0.2% of the total weight of various raw materials is added;

[0045] The 58% of the aggregate is composed of 18% of waste corundum-mullite bricks with a particle size ≤ 3 mm, 23% of recycled corundum with a particle size ≤ 3 mm and 17% of recycled fused corundum with a particle size ≤ 3 mm;

[0046] 32% of the powder material consists of 17% of waste corundum-mullite bricks with a particle size ≤ 0.037 mm, 10% of recycled corundum with a particle size ≤ 0.074 mm, 3% of recycled fused corundum with a particle size ≤ 0.074 mm, and 2% of α-aluminum oxide micropowder with a particle size ≤ 0.045 mm.

[0047] 7% of the additive consists of 1% of silica fume, 1.5% of nano-silica fume, 3% of bentonite, and 1.5% of mullite whiskers;

[0048] 3% of the binder consists of 0.5% of sodium tripolyphosphate, 0.5% of sodium hexametaphosphate, 1% of industrial glucose, 0.3% of carboxymethyl cellulose, and 0.7% of solid water glass;

[0049] The external additive is an explosion-proof fiber composed of polyethylene, polypropylene, and polyester fiber.

[0050] The preparation method of the corundum-based daubing material described in Example 2 is the same as that in Example 1.

[0051] After the corundum-based daubing material prepared in this example is subjected to construction operations, samples of the daubing material are taken for testing: the bulk density after drying at 110°C for 24 h is 2.58 g / cm 3 , the bulk density after heat treatment at 600°C for 3 h is 2.63 g / cm 3 , the bulk density after heat treatment at 1200°C for 3 h is 2.74 g / cm 3 ; the bulk density after heat treatment at 1400°C for 3 h is 2.91 g / cm 3 .

[0052] The corundum-mullite bricks are cut into specimens of 40×40×60 mm. The daubing material prepared in this example is used to bond the brick specimens, and the flexural strength of the bonded specimens is measured after heat treatment at the corresponding temperature. The flexural strength after drying at 110°C for 24 h is 2.4 MPa; the flexural strength after heat treatment at 600°C for 3 h is 1.9 MPa; the flexural strength after heat treatment at 1200°C for 3 h is 4.7 MPa; the flexural strength after heat treatment at 1400°C for 3 h is 5.1 MPa.

[0053] Example 3:

[0054] The corundum-based daubing material of the present invention, expressed in mass percentage, consists of 60% of aggregate, 30% of powder material, 7% of additive, and 3% of binder; in addition, an external additive accounting for 0.2% of the total weight of various raw materials is added;

[0055] 60% of the aggregate consists of 21% of waste corundum-mullite bricks with a particle size ≤ 3 mm, 20% of recycled corundum with a particle size ≤ 3 mm, and 19% of recycled fused corundum with a particle size ≤ 3 mm;

[0056] 30% of the powder consists of 19% of waste corundum-mullite bricks with a particle size ≤ 0.037 mm, 8% of recycled corundum with a particle size ≤ 0.074 mm, 2% of recycled fused corundum with a particle size ≤ 0.074 mm, and 1% of α-aluminum oxide micropowder with a particle size ≤ 0.045 mm.

[0057] 7% of the additive consists of 1% of silica powder, 1% of nano-silica powder, 3% of bentonite, and 2% of mullite whiskers;

[0058] 3% of the binder consists of 0.5% of sodium tripolyphosphate, 0.5% of sodium hexametaphosphate, 1% of industrial glucose, 0.3% of carboxymethyl cellulose, and 0.7% of solid water glass;

[0059] The admixture is an explosion-proof fiber made of a mixture of polyethylene, polypropylene, and polyester fiber.

[0060] The preparation method of the corundum-based coating material described in Example 3 is the same as that in Example 1.

[0061] After the corundum-based coating material prepared in this example is constructed, samples of the coating material are taken for testing: the bulk density after drying at 110°C for 24 h is 2.63 g / cm 3 , the bulk density after heat treatment at 600°C for 3 h is 2.68 g / cm 3 , the bulk density after heat treatment at 1200°C for 3 h is 2.75 g / cm 3 ; the bulk density after heat treatment at 1400°C for 3 h is 2.93 g / cm 3 .

[0062] The corundum-mullite bricks are cut into specimens of 40×40×60 mm. The coating material is used to bond the brick specimens, and the flexural strength of the bonded specimens is measured after heat treatment at the corresponding temperature. The flexural strength after drying at 110°C for 24 h is 2.6 MPa; the flexural strength after heat treatment at 600°C for 3 h is 2.1 MPa; the flexural strength after heat treatment at 1200°C for 3 h is 4.9 MPa; the flexural strength after heat treatment at 1400°C for 3 h is 5.7 MPa.

[0063] Comparative example:

[0064] A corundum-based coating material, expressed in mass percentage, consists of 60% of aggregate, 32% of powder, 5% of additive, and 3% of binder; in addition, an admixture accounting for 0.2% of the total weight of various raw materials is added.

[0065] 60% of the aggregate consists of 29% of brown corundum ≤ 3 mm, 13% of fused white corundum ≤ 3 mm, and 18% of sintered mullite ≤ 3 mm;

[0066] 32% of the powder consists of 17% brown fused alumina with a particle size of ≤0.037 mm, 10% fused white alumina with a particle size of ≤0.037 mm, 3% sintered mullite with a particle size of ≤0.037 mm, and 2% α-alumina micropowder with a particle size of ≤0.045 mm;

[0067] 5% of the additive consists of 1% silica powder, 1% nano-silica powder, 1% bentonite, and 2% mullite whiskers; 3% of the binder consists of 0.5% sodium tripolyphosphate, 0.5% sodium hexametaphosphate, 1% industrial glucose, 0.5% carboxymethyl cellulose, and 0.5% solid water glass; The admixture is an explosion-proof fiber made of a mixture of polyethylene, polypropylene, and polyester fiber.

[0068] The brown fused alumina used has an Al2O3 content of ≥95.5%, SiO2 ≤1.8%, TiO2 ≤2.5%, and Na2O ≤3.8%; the fused white alumina has a white alumina Al2O3 content of ≥99.5%, SiO2 ≤0.9%, Fe2O3 ≤0.2%, and Na2O ≤0.1%; the sintered mullite has a mullite Al2O3 content of ≥70.2%, SiO2 ≤28.5%, Fe2O3 ≤1.5%, and R2O ≤0.6%; the α-alumina micropowder has an Al2O3 content of ≥99.7%.

[0069] The preparation method of the corundum-based coating material in the comparative example is as follows:

[0070] a. Weigh various raw materials according to the mixing ratio of the corundum-based coating material in the comparative example;

[0071] b. Place the weighed aggregate, powder, additive, binder, and admixture in a forced mixer and stir and mix. After stirring for 8 minutes, add tap water accounting for 9% of the total weight of all raw materials and continue to stir forcibly for 8 minutes. Wait until the obtained coating material becomes a mud paste and discharge it for standby.

[0072] Perform coating material construction operations on the corundum-based coating material prepared in the comparative example, and then take samples of the coating material for testing: the bulk density after drying at 110°C for 24 hours is 2.51 g / cm 3 , the bulk density after heat treatment at 600°C for 3 hours is 2.64 g / cm 3 , the bulk density after heat treatment at 1200°C for 3 hours is 2.73 g / cm 3 ; the bulk density after heat treatment at 1400°C for 3 hours is 2.85 g / cm 3 .

[0073] The magnesia-zirconia bricks were cut into specimens with dimensions of 40×40×60 mm. The coating material prepared by the comparative example was used to bond the brick specimens. After heat treatment at the corresponding temperature, the flexural strength of the bonded specimens was measured. The flexural strength after drying at 110°C for 24 h was 2.3 MPa; the flexural strength after heat treatment at 600°C for 3 h was 1.6 MPa; the flexural strength after heat treatment at 1200°C for 3 h was 2.9 MPa; and the flexural strength after heat treatment at 1400°C for 3 h was 3.3 MPa.

Claims

1. A corundum-based coating material, characterized in that: In terms of mass percentage, the corundum-based coating material mainly consists of 57-67% of aggregate, 22-32% of powder, 5-12% of additive, and 1-4% of binder; in addition, an admixture accounting for 0.1-1% of the total weight of all raw materials is added. The 57-67% of the aggregate consists of 15-22% of waste corundum-mullite bricks with a particle size ≤ 3 mm, 20-26% of recycled corundum with a particle size ≤ 3 mm, and 16-23% of recycled fused corundum with a particle size ≤ 3 mm. The 22-32% of the powder consists of 12-19% of waste corundum-mullite bricks with a particle size ≤ 0.037 mm, 5-12% of recycled corundum with a particle size ≤ 0.074 mm, 2-7% of recycled fused corundum with a particle size ≤ 0.074 mm, and 1-3% of α-alumina micropowder with a particle size ≤ 0.045 mm.

2. The corundum-based coating material according to claim 1, characterized in that: The Al2O3 content in the waste corundum-mullite brick is ≥ 78%, and the SiO2 content is ≤ 25%; the waste corundum-mullite brick is directly crushed into the corresponding particle size from the recycled corundum-mullite brick after use.

3. The corundum-based coating material according to claim 1, characterized in that: The Al2O3 content in the recycled corundum is ≥ 80%, the TiO2 content is ≤ 2.5%, the Fe2O3 content is ≤ 1.5%, and the CaO content is ≤ 3%. The recycled corundum is obtained by classifying and sorting the used corundum refractory bricks, removing the working layer, crushing, soaking and cleaning, drying, cooling, and secondary crushing, and finally screening into different required particle sizes.

4. The corundum-based coating material according to claim 1, characterized in that: The Al2O3 content in the recycled fused corundum is ≥ 85%, the Fe2O3 content is ≤ 1.0%, and the CaO content is ≤ 1.0%. The recycled fused corundum is obtained by classifying and sorting the used fused corundum refractory bricks, removing the working layer, crushing, soaking and cleaning, drying, cooling, and secondary crushing, and finally screening into different required particle sizes.

5. The corundum-based coating material according to claim 1, characterized in that: The additive consists of silica fume, nano-silica fume, bentonite, and mullite whiskers; the mass ratio among the silica fume, nano-silica fume, bentonite, and mullite whiskers is 1-2:1-2:1-3:1-2.

6. The corundum-based coating material according to claim 1, wherein: The binder consists of sodium tripolyphosphate, sodium hexametaphosphate, industrial glucose, carboxymethyl cellulose, and solid water glass; the mass ratio among the sodium tripolyphosphate, sodium hexametaphosphate, industrial glucose, carboxymethyl cellulose, and solid water glass is 4-6:4-6:8-10:3-5:5-7.

7. The corundum-based coating material according to claim 1, characterized in that: The admixture is an explosion-proof fiber composed of polyethylene, polypropylene, and polyester fiber.

8. A preparation method of a corundum-based coating material, characterized in that, The preparation method includes the following steps: a. Weigh various raw materials according to the proportion of the corundum-based coating material described in Claim 1. b. Place the weighed aggregate, powder, additive, binder, and admixture in a forced mixer for stirring and mixing for 5-10 minutes, then add tap water accounting for 5-10% of the total weight of all raw materials and continue forced stirring for 5-8 minutes, and wait until the obtained coating material becomes a mud paste and discharge it for standby.