Gunning mix for electric arc furnace

Abstract

The invention relates to an electric arc furnace gunning mix which comprises the following components in parts by weight: 35-55 parts of bauxite, 15-25 parts of silicon carbide (SiC), 10-25 parts of white corundum, 3-8 parts of silicon oxide (SiO2), 2-5 parts of silicon nitride (Si3N4), 0-3 parts of zirconium diboride (ZrB2), 3-8 parts of coke powder, 0-8 parts of a sintering aid and 5-10 parts of a binding agent, and the zirconium diboride is not zero. The method has the beneficial effects that a high-temperature ceramic body containing a ZrB2-SiC multiphase material is generated at a damaged furnace lining part through added zirconium diboride and silicon carbide and coke powder in the zirconium diboride under the action of a sintering aid, and the high-temperature ceramic body has good oxidation resistance, thermal shock resistance and ablation resistance, so that the service life of the electric arc furnace lining can be greatly prolonged.

Description

Technical Field

[0001] The invention relates to the technical field of refractory materials, and in particular to an arc furnace gunning material used for online gunning and repairing of arc furnace lining without stopping the furnace. Background Art

[0002] With the improvement of electric arc furnace equipment, the improvement of smelting technology and the rapid development of the electric power industry, the cost of electric arc furnace steelmaking has continued to decrease. Electric arc furnaces are no longer used mainly to produce alloy steel as they were originally, but are also used in large quantities to produce ordinary carbon steel. The proportion of their output in the total steel output of major industrial countries continues to rise.

[0003] The lining of an electric furnace is generally built with magnesium-carbon refractory materials, which are easily damaged by the erosion of high-temperature molten steel and slag, resulting in a short service life of the electric furnace. Usually, repeated maintenance and repair are required during the service life of an electric furnace. At present, the most commonly used method is to use gunning materials to repair the lining online without stopping the furnace. Since the electric arc furnace needs to withstand complex and periodic slag chemical erosion during the smelting process, the refractory materials used for the lining need to have excellent high temperature strength resistance, anti-penetration performance, slag erosion resistance, thermal shock resistance and resistance to molten steel erosion. A Chinese patent with authorization announcement number CN 112225541 B discloses a dry electric furnace gunning material suitable for high-titanium blast furnace slag, and also discloses an electric furnace protection method using the electric furnace gunning material. The gunning material has MgO and Al2O3 in it reacting on the surface of the electric furnace lining at a temperature of up to 1500°C to 1650°C to form magnesia-alumina spinel (magnesia-alumina spinel has a melting point of up to 2135°C), and MgO and TiO2 reacting to form magnesia-titanium spinel embedded around the magnesia-alumina spinel, so as to enhance the gunning material's resistance to slag invasion and improve the furnace life. However, the electric furnace protection method described in the patent requires regular (every 3 to 7 times after the electric furnace has been used for 200 to 300 times) gunning operation on the slag outlet area inside the electric furnace, and the gunning material in the patent and most of the currently available gunning materials have low adhesion rate and adhesion, resulting in low high-temperature strength, thermal shock resistance and ablation resistance, which restricts the long-life use of the electric furnace. Summary of the invention

[0004] In order to overcome the defects of the prior art, the technical problem solved by the present invention is to provide an electric arc furnace gunning material, which generates a high-temperature ceramic body containing ZrB2-SiC composite material at the damaged furnace lining part through the added zirconium diboride and the silicon carbide and coke powder therein under the action of sintering aids, and has good anti-oxidation, thermal shock and ablation resistance, thereby greatly improving the service life of the electric arc furnace lining.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] An arc furnace gunning material, characterized in that its components are calculated by weight:

[0007] 35-55 parts of bauxite, 15-25 parts of silicon carbide (SiC), 10-25 parts of white corundum, 3-8 parts of silicon oxide (SiO2), 2-5 parts of silicon nitride (Si3N4), 0-3 parts of zirconium diboride (ZrB2), 3-8 parts of coke powder, 0-8 parts of sintering aid, 5-10 parts of binder, and the content of zirconium diboride and sintering aid is not zero.

[0008] The combustion aid is Mo or B4C or a mixture of the two.

[0009] The binder is a mixture of pure calcium aluminate cement, asphalt binder and anthracene oil.

[0010] Furthermore, the ratio of the bauxite particles is: 3mm<particle size≤5mm:1mm<particle size≤3mm:particle size<1mm=1:2:3.

[0011] Furthermore, the ratio of the particles of the white corundum is: 3mm<particle size≤5mm:1mm<particle size≤3mm:particle size<1mm=1:1.5:1.

[0012] Furthermore, the silicon carbide is commercial submicron SiC powder;

[0013] The particle size of the coke powder is 320 mesh;

[0014] The particle size of the silicon oxide is 325 mesh;

[0015] The particle size of the silicon nitride is 325 mesh;

[0016] The particle size of the zirconium diboride is ≤200nm.

[0017] Furthermore, in the bauxite, Al2O3≥90wt%, Fe2O3≤0.5wt%, CaO≤0.6wt%, and particle volume density≥3.6g / cm 3 .

[0018] Furthermore, the oxygen content of the zirconium diboride (ZrB2) is less than 1.0 wt%.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] 1) In the gunning material of the present invention, bauxite and white corundum are the main sources of aluminum oxide (Al2O3) in the gunning material, and oxides such as aluminum oxide (Al2O3), silicon oxide (SiO2), and calcium oxide (CaO) are one of the main components of high-temperature ceramics. These oxides have excellent high-temperature resistance and chemical stability, and can maintain the strength and stability of the material under high-temperature environments; non-oxides such as silicon carbide (SiC) and silicon nitride (Si3N4) are another main component of high-temperature ceramics. These non-oxides have high strength, high hardness and excellent thermal conductivity, and can maintain the stability and strength of the material under high-temperature environments;

[0021] 2) In the gunning material of the present invention, by introducing the boride of transition metals, zirconium diboride (ZrB2) and the silicon carbide and coke powder therein, a high-temperature ceramic body containing ZrB2-SiC composite material is generated at the damaged furnace lining under the action of a sintering aid. This ceramic body has good oxidation resistance, thermal shock resistance and ablation resistance, and is firmly adhered to the outer surface of the furnace lining. Its high-temperature strength, heat resistance, oxidation resistance and slag erosion resistance are even better than those of the original furnace lining refractory materials, thereby further greatly improving the service life of the electric arc furnace lining;

[0022] 3) In the gunning material of the present invention, the main raw material is bauxite. The refractoriness of bauxite clinker is as high as 1780°C, it has strong chemical stability and good physical properties, and it is one of the main raw materials for refractory products. In addition, the cost of bauxite is low, which can greatly reduce the manufacturing cost of the gunning material. DETAILED DESCRIPTION

[0023] The technical solution of the present invention will be further clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0024] The embodiment of the present invention provides an arc furnace gunning material, the components of which are as follows by weight:

[0025] 35-55 parts of bauxite, 15-25 parts of silicon carbide (SiC), 10-25 parts of white corundum, 3-8 parts of silicon oxide (SiO2), 2-5 parts of silicon nitride (Si3N4), 0-3 parts of zirconium diboride (ZrB2), 3-8 parts of coke powder, 0-8 parts of sintering aid, 5-10 parts of binder, and the content of zirconium diboride and sintering aid is not zero.

[0026] The main component of the arc furnace gunning material of the present invention, aluminum oxide (Al2O3), comes from bauxite and white corundum with an Al2O3 content greater than or equal to 90wt%, while oxides such as aluminum oxide (Al2O3), silicon oxide (SiO2), and calcium oxide (CaO) (from bauxite and pure calcium aluminate cement binder) are one of the main components of high-temperature ceramics. These oxides have excellent high-temperature resistance and chemical stability, and can maintain the strength and stability of the material under high-temperature environment.

[0027] In addition, non-oxides such as silicon carbide (SiC) and silicon nitride (Si3N4) are another main component of high-temperature ceramics. These non-oxides have high strength, high hardness and excellent thermal conductivity, and can maintain the stability and strength of the material in high-temperature environments.

[0028] Furthermore, in the arc furnace gunning material of the present invention, by introducing the boride of transition metals - zirconium diboride (ZrB2) and silicon carbide and coke powder in the gunning material, a high-temperature ceramic body containing ZrB2-SiC composite material is generated at the damaged furnace lining under the action of a sintering aid. This ceramic body has good antioxidant, thermal shock and ablation resistance, thereby further greatly improving the service life of the arc furnace lining.

[0029] In some embodiments, the gunning material is sprayed to the surface of the arc furnace lining at 1500°C to 1650°C by argon gas, and the zirconium diboride (ZrB2) introduced therein is respectively 4wt% Mo or 4wt% Mo-2wt% B4C as a sintering aid, and the argon gas and oxygen in the air assist the combustion of coke powder, and the sintering aid is used to instantly raise the surface temperature of the furnace lining to 2100°C to 2300°C, and the commercial submicron SiC powder is used as the second phase, and the surface temperature of the arc furnace is achieved. Normal pressure sintering of ZrB2-SiC material can generate high temperature ceramic body containing ZrB2-SiC composite material, which is firmly adhered to the outer surface of electric furnace lining. Its high temperature strength, heat resistance, oxidation resistance and slag erosion resistance are even better than the original lining refractory materials. In addition, coke powder is not only an auxiliary agent for combustion and heating, but also because its main component is carbon, which is not wetted by slag and does not react with slag, it can improve the thermal shock stability and slag erosion resistance of the material.

[0030] [Example 1]:

[0031] An arc furnace gunning material, the components of which are calculated by weight:

[0032] 43 parts of bauxite, 16 parts of silicon carbide (SiC), 24 parts of white corundum, 3 parts of silicon oxide (SiO2), 2.5 parts of silicon nitride (Si3N4), 0.5 parts of zirconium diboride (ZrB2), 3.5 parts of coke powder, 1.5 parts of sintering aid, and 6 parts of binder.

[0033] The ratio of the bauxite particles is: 3mm<particle size≤5mm:1mm<particle size≤3mm:particle size<1mm=1:2:3;

[0034] The ratio of the white corundum particles is: 3mm<particle size≤5mm:1mm<particle size≤3mm:particle size<1mm=1:1.5:1;

[0035] The combustion aid is a mixture of Mo and B4C, wherein the ratio of Mo to B4C is 2:1.

[0036] The binder is a mixture of pure calcium aluminate cement, asphalt binder and anthracene oil, and the ratio thereof is pure calcium aluminate cement: asphalt binder: anthracene oil = 1:2:1.

[0037] Preparation method: According to the above proportions, prepare the raw materials except the binder into a mixture, stir it in a mixer for 2 minutes, then add the binder and continue stirring for 3 minutes to obtain the gunning material.

[0038] In actual work, when the computer detects and determines the burnt parts of the electric furnace lining and after the electric furnace is tapped, the gunning material is immediately used with argon as the carrier gas to perform gunning operations on the weak areas of the electric furnace lining. The gas-solid ratio of argon to gunning material is 6:1. The gunning material is sprayed to the surface of the electric arc furnace lining at about 1650°C. The zirconium diboride (ZrB2) introduced therein is a mixture of Mo and B4C as a sintering aid. Argon and oxygen in the air help to burn coke powder, and with the help of the sintering aid, the surface temperature of the lining is instantly raised to about 2150°C. With commercial submicron SiC powder as the second phase, the atmospheric pressure sintering of ZrB2-SiC material is achieved on the surface of the electric arc furnace lining, which can generate ZrB2-SiC-containing The high-temperature ceramic body of the 2-SiC composite material is firmly adhered to the outer surface of the furnace lining. Its high-temperature strength, heat resistance, oxidation resistance, slag erosion resistance and other performance indicators are better than those of the original furnace lining refractory materials. It is not limited to the spraying operation of the slag outlet area inside the electric furnace, and there is no need to spray the slag outlet area inside the electric furnace regularly (after the electric furnace has been used for 200 to 300 times, every 3 to 7 heats). The maintenance time and cost of the electric furnace are greatly reduced, and the service life of the electric furnace is greatly improved.

[0039] [Example 2]:

[0040] An arc furnace gunning material, the components of which are calculated by weight:

[0041] 47.5 parts of bauxite, 20 parts of silicon carbide (SiC), 14.5 parts of white corundum, 2.5 parts of silicon oxide (SiO2), 2 parts of silicon nitride (Si3N4), 1.5 parts of zirconium diboride (ZrB2), 4.5 parts of coke powder, 2.5 parts of sintering aid, and 5 parts of binder.

[0042] The ratio of the bauxite particles is: 3mm<particle size≤5mm:1mm<particle size≤3mm:particle size<1mm=1:2:3;

[0043] The ratio of the particles of the white corundum is: 3mm<particle size≤5mm:1mm<particle size≤3mm:particle size<1mm=1:1.5:1;

[0044] The combustion aid is Mo.

[0045] The binder is a mixture of pure calcium aluminate cement, asphalt binder and anthracene oil, and the ratio thereof is pure calcium aluminate cement: asphalt binder: anthracene oil = 1:2:1.

[0046] The preparation method is the same as [Example 1].

[0047] In actual work, the method of use is basically the same as that of [Example 1], except that the gas-solid ratio of argon and gunning material is adjusted to 5.5:1 (due to the increase in the weight ratio of ultrafine silicon carbide (SiC) powder, coke powder, etc., the fluidity of the material is increased), the sintering aid is adjusted to Mo and the amount is increased. Argon and oxygen in the air help the combustion of coke powder, assisted by the sintering aid Mo, so that the surface temperature of the furnace lining is instantly raised to about 2200°C, which is beneficial to the atmospheric pressure sintering molding of ZrB2-SiC material.

[0048] [Example 3]:

[0049] 38.5 parts of bauxite, 22.5 parts of silicon carbide (SiC), 12.5 parts of white corundum, 3.5 parts of silicon oxide (SiO2), 2.5 parts of silicon nitride (Si3N4), 2.5 parts of zirconium diboride (ZrB2), 7 parts of coke powder, 6 parts of sintering aid, and 5 parts of binder.

[0050] The ratio of the bauxite particles is: 3mm<particle size≤5mm:1mm<particle size≤3mm:particle size<1mm=1:2:3;

[0051] The ratio of the white corundum particles is: 3mm<particle size≤5mm:1mm<particle size≤3mm:particle size<1mm=1:1.5:1;

[0052] The combustion aid is a mixture of Mo and B4C, wherein the ratio of Mo to B4C is 2:1.

[0053] The binder is a mixture of pure calcium aluminate cement, asphalt binder and anthracene oil, and the ratio thereof is pure calcium aluminate cement: asphalt binder: anthracene oil = 1:2:1.

[0054] The preparation method is the same as [Example 1].

[0055] In actual work, the method of use is basically the same as that of [Example 1], except that the gas-solid ratio of argon and gunning material is adjusted to 5:1 (due to the increase in the weight ratio of silicon carbide (SiC) ultrafine powder, coke powder, etc., the fluidity of the material increases), the sintering aid is a mixture of Mo and B4C, wherein the ratio of Mo to B4C is 2:1, but the weight ratio is adjusted from 1.5 parts to 6 parts, and the argon and oxygen in the air assist the combustion of coke powder, assisted by the sintering aid, so that the surface temperature of the furnace lining is instantly raised to about 2250°C, which is the optimal temperature range for atmospheric pressure sintering of ZrB2-SiC material.

[0056] [Example 4]:

[0057] 36.5 parts of bauxite, 23.5 parts of silicon carbide (SiC), 11.5 parts of white corundum, 2.5 parts of silicon oxide (SiO2), 2.5 parts of silicon nitride (Si3N4), 3 parts of zirconium diboride (ZrB2), 8 parts of coke powder, 7.5 parts of sintering aid, and 5 parts of binder.

[0058] The ratio of the bauxite particles is: 3mm<particle size≤5mm:1mm<particle size≤3mm:particle size<1mm=1:2:3;

[0059] The ratio of the white corundum particles is: 3mm<particle size≤5mm:1mm<particle size≤3mm:particle size<1mm=1:1.5:1;

[0060] The combustion aid is a mixture of Mo and B4C, wherein the ratio of Mo to B4C is 2:1.

[0061] The binder is a mixture of pure calcium aluminate cement, asphalt binder and anthracene oil, and the ratio thereof is pure calcium aluminate cement: asphalt binder: anthracene oil = 1:2:1.

[0062] The preparation method of the gunning material is the same as [Example 1].

[0063] In actual work, the method of use is basically the same as that of [Example 3], except that the gas-solid ratio of argon and gunning material is adjusted to 4.5:1 (due to the increase in the weight ratio of ultrafine silicon carbide (SiC) powder, coke powder, etc., the fluidity of the material increases), the sintering aid is a mixture of Mo and B4C, wherein the ratio of Mo to B4C is 2:1, but the weight ratio is adjusted from 6 parts to 7.5 parts, and argon and oxygen in the air assist the combustion of coke powder, which, together with the sintering aid, can instantly increase the surface temperature of the furnace lining to about 2300°C.

[0064] [Example 5]:

[0065] An arc furnace gunning material, the components of which are calculated by weight:

[0066] 43.5 parts of bauxite, 16.5 parts of silicon carbide (SiC), 24 parts of white corundum, 3.5 parts of silicon oxide (SiO2), 2.5 parts of silicon nitride (Si3N4), 0 parts of zirconium diboride (ZrB2), 3.5 parts of coke powder, 0 parts of sintering aid, and 6.5 parts of binder.

[0067] The ratio of the bauxite particles is: 3mm<particle size≤5mm:1mm<particle size≤3mm:particle size<1mm=1:2:3;

[0068] The ratio of the white corundum particles is: 3mm<particle size≤5mm:1mm<particle size≤3mm:particle size<1mm=1:1.5:1;

[0069] The binder is a mixture of pure calcium aluminate cement, asphalt binder and anthracene oil, and the ratio thereof is pure calcium aluminate cement: asphalt binder: anthracene oil = 1:2:1.

[0070] The preparation method of the gunning material is the same as [Example 1].

[0071] In actual work, the method of use is basically the same as that of [Examples 1-4]. The main difference is that the weight ratio of zirconium diboride (ZrB2) and sintering aid is adjusted to 0, that is, no boride of transition metals with good oxidation resistance, thermal shock resistance and ablation resistance is introduced, and a high-temperature ceramic body without ZrB2-SiC composite material is generated on the surface of the electric arc furnace lining, which is firmly adhered to the outer surface of the lining. The performance indicators of this high-temperature ceramic body, such as high-temperature strength, heat resistance, oxidation resistance and slag erosion resistance, are significantly reduced compared with those of Examples 1-4, but are also close to or better than the original lining refractory materials.

[0072] The spray coatings of each embodiment of the present invention have significantly better high-temperature strength performance, thermal shock resistance, and slag erosion resistance. In contrast, from Example 1 to Example 3, with the gradual increase in the weight ratio of zirconium diboride (ZrB2) and sintering aids, and the increase in the instantaneous sintering temperature, the performance of the ZrB2-SiC composite material formed by atmospheric pressure sintering is getting better and better. However, with the further increase in the weight ratio of zirconium diboride (ZrB2) and sintering aids, and the further increase in the instantaneous sintering temperature (exceeding 2250°C), the performance of the sintered ZrB2-SiC composite material becomes worse, such as the high-temperature ceramic body of the ZrB2-SiC composite material formed in Example 4 is worse than that of Example 3.

[0073] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. An arc furnace gunning material, characterized in that: Its components are calculated by weight: 35-55 parts of bauxite, 15-25 parts of silicon carbide, 10-25 parts of white corundum, 3-8 parts of silicon oxide, 2-5 parts of silicon nitride, 0-3 parts of zirconium diboride, 3-8 parts of coke powder, 0-8 parts of sintering aid, 5-10 parts of binder, and the content of zirconium diboride and sintering aid is not zero.

2. The arc furnace gunning material according to claim 1, characterized in that: The combustion aid is Mo or B4C or a mixture of the two.

3. The arc furnace gunning material according to claim 1, characterized in that: The binder is a mixture of pure calcium aluminate cement, asphalt binder and anthracene oil.

4. The arc furnace gunning material according to claim 1, characterized in that: The ratio of the bauxite particles is: 3mm<particle size≤5mm:1mm<particle size≤3mm:particle size<1mm=1:2:

3.

5. The arc furnace gunning material according to claim 1, characterized in that: The ratio of the particles of the white corundum is: 3mm<particle size≤5mm:1mm<particle size≤3mm:particle size<1mm=1:1.5:

1.

6. The arc furnace gunning material according to claim 1, characterized in that: The silicon carbide is commercial submicron SiC powder; The particle size of the coke powder is 320 mesh; The particle size of the silicon oxide is 325 mesh; The particle size of the silicon nitride is 325 mesh; The particle size of the zirconium diboride is ≤200nm.

7. The arc furnace gunning material according to claim 1, characterized in that: In the bauxite, Al2O3≥90wt%, Fe2O3≤0.5wt%, CaO≤0.6wt%, and particle volume density≥3.6g / cm 3 .

8. The arc furnace gunning material according to claim 1, characterized in that: The oxygen content of the zirconium diboride is less than 1.0 wt %.