Preparation and construction method of silicon carbide composite refractory material for wet injection of blast furnace lining

Abstract

The invention relates to the technical field of refractory materials, and discloses a preparation and construction method of a silicon carbide composite refractory material for wet injection of a blast furnace lining, and is characterized in that the preparation method comprises the following steps: raw material selection and pretreatment, micro powder and reinforcing phase preparation, batching, dry mixing, binding agent addition, wet mixing and adjustment, and quality control; the construction method comprises the steps of furnace washing, in-furnace injection, gunning equipment dismounting and furnace baking. The silicon carbide composite refractory material has the component characteristics that Al2O3 is more than or equal to 70%, SiC is more than or equal to 13% and CaO is less than or equal to 0.5%, the volume density is more than or equal to 2.85 g / cm < 3 >, the breaking strength is more than or equal to 12 MPa, the compression strength is more than or equal to 80 MPa, the linear change rate after burning is + / -0.5%, the construction rebound rate is less than or equal to 5%, and the silicon carbide composite refractory material has the advantages of high bonding and falling resistance, low porosity, high compactness, rapid slagging and self-protection, environment-friendly construction characteristics, long service life and high efficiency.

Description

Technical Field

[0001] This invention relates to the field of refractory materials technology, specifically to the preparation and construction method of a silicon carbide composite refractory material for wet injection into blast furnace linings. Background Technology

[0002] During long-term operation, blast furnaces are subject to damage from multiple factors, including wear of the furnace material, erosion by gas, corrosion by alkali metals, and temperature fluctuations. This damage can severely affect the smooth operation and service life of the blast furnace. Traditional blast furnace lining repair methods often use cement-bonded injection materials, which have drawbacks such as high porosity, poor erosion resistance, low bonding strength, long drying time, and susceptibility to cracking and detachment. Furthermore, the high rebound rate during construction can have a significant impact on the environment.

[0003] Although various injection materials have emerged in the market, their overall performance still cannot meet the requirements of high-intensity smelting and long-life operation of blast furnaces. In particular, there is still significant room for improvement in terms of resistance to molten iron erosion, thermal shock stability, rapid slag adhesion, and environmentally friendly construction performance. Therefore, the development of a silicon carbide composite refractory material for wet injection of blast furnace lining with high adhesion and anti-detachment properties, low porosity and high density, rapid slag formation for self-protection, environmentally friendly construction, long life and high efficiency, as well as its preparation and construction method, has important industrial application value. Summary of the Invention

[0004] (a) Technical problems to be solved To address the shortcomings of existing technologies, this invention provides a method for preparing and constructing silicon carbide composite refractory materials for wet injection into blast furnace linings. This material possesses advantages such as high adhesion and resistance to detachment, low porosity and high density, rapid slagging for self-protection, environmentally friendly construction, long service life, and high efficiency. It solves the problems of high porosity, poor erosion resistance, low bonding strength, long furnace drying time, and susceptibility to cracking and detachment, as well as the high rebound rate during construction, which causes significant environmental impact.

[0005] (II) Technical Solution To achieve the aforementioned goals of high adhesion and anti-detachment, low porosity and high density, rapid slagging for self-protection, environmentally friendly construction, long service life and high efficiency, this invention provides the following technical solution: A method for preparing silicon carbide composite refractory material for wet injection into blast furnace linings, characterized by comprising the following steps: S1. Raw material selection and pretreatment: Selected low-alkali bauxite clinker, dense fused alumina, mullite, silicon carbide and high-alumina microcrystalline ceramics from Shanxi Province are crushed and screened respectively, and the particle size distribution is controlled to achieve the densest packing. Stable zirconia ZrO2 is selected as the reinforcing phase for later use. S2. Preparation of micro powder and reinforcing phase: Dense fused alumina is ultra-finely ground to 800 mesh to obtain fused alumina micro powder, silicon carbide is ultra-finely pulverized to 800 mesh and stored for later use, and stabilized zirconium oxide ZrO2 is ultra-finely pulverized to 2000 mesh and stored separately for later use. S3. Ingredients: By mass percentage, the raw material composition is as follows: Shanxi low-alkali bauxite clinker (0-8mm) 40%, dense fused alumina (1-5mm) 20%, mullite (1-3mm) 15%, silicon carbide (0-1mm, w=97%) 10%, silicon carbide (800 mesh) 5%, high-alumina microcrystalline ceramic (0-3mm) 8%, fused alumina micro powder (800 mesh) 0.5~1.5%, zirconium oxide (2000 mesh) 0.5~1%; S4. Dry mixing: The aggregates of each grade in step S3, along with the micro powder and zirconium oxide reinforcing phase, are put into a high-efficiency forced mixer for dry mixing. S5. Adding binder: After dry mixing is even, slowly add silica sol binder and coagulant accelerator and continue stirring to form a uniform wet mixture; S6. Wet mixing and adjustment: Add an appropriate amount of water to adjust the fluidity of the slurry according to the state of the wet mixture, control the viscosity required for construction, and the finished sprayable material is obtained after mixing. S7. Quality Control: Take a small amount of the finished sprayed material, dry and bake it, and then take samples to test its physicochemical properties.

[0006] Preferably, 800-mesh fused alumina micro powder can improve the sintering activity and flowability of the material; Preferably, in step S4, the mixture is dry-mixed for 10–15 minutes until the color is uniform and there are no lumps. Preferably, after adding the silica sol binder and coagulant in step S5, continue stirring for 5–8 minutes to ensure that the binder fully coats the particle surface and forms a uniform wet mixture. Preferably, the physicochemical properties of the finished sprayed material tested in step S7 must meet the following requirements: Al2O3 ≥ 70%, SiC ≥ 13%, CaO ≤ 0.5%, and bulk density ≥ 2.85 g / cm³. 3 (110℃×24h), flexural strength ≥12MPa (1400℃×3h), compressive strength ≥80MPa, linear change rate after burning ±0.5% (1400℃×3h), construction rebound rate ≤5%.

[0007] A method for constructing a silicon carbide composite refractory material for wet injection into blast furnace linings, characterized in that the injection material obtained by any one of the preparation methods described in claims 1-5 includes the following steps: S1, Cleaning the furnace; S2, In-furnace injection; S3. Remove the spraying equipment; S4, Oven.

[0008] Preferably, in step S1, high-pressure atomized water at a pressure of 30MPa and a flow rate of ≤1 ton per hour is used to clean the residual furnace lining, loose material, and dust inside the furnace twice, from top to bottom and then from bottom to top.

[0009] Preferably, in step S2, before spraying, check and open the tuyeres and manholes of the gas hood to ensure air circulation. The newly formed furnace lining must meet the furnace size requirements, have a smooth surface, and the spraying thickness must be controlled within the required range. Construction is carried out according to the thickness requirements of each part, depending on the specific requirements. For the furnace belly, furnace waist, and the lower 7-12 sections of the copper cooling wall dovetail grooves, sprayed refractory is used. The hot surface of the furnace belly and furnace waist is sprayed 60mm, the lower part of the furnace body is sprayed 20mm, the ductile iron cooling wall linings in the middle 12, 13, and 14 sections of the furnace body have a brick thickness of 20mm, and the dovetail grooves of the upper 15-17 sections of the ductile iron cooling wall are sprayed with refractory, with a hot surface spraying thickness of 50mm. This ensures a smooth transition from the furnace belly to the hot surface of the furnace body cooling wall. To ensure the best spraying effect, the following technical measures are taken: 1) Based on the inner diameter of each part, the injection operator adjusts the position and angle according to the distance from the wall. During the injection process, the air pressure and air volume, the discharge volume and the amount of accelerator added are all adjusted in a timely manner according to the actual situation to ensure that the rebound of the blast furnace injection is minimized. 2) Depending on the different parts of the furnace lining to be sprayed, the sprayer should select the distance and angle between the sprayer and the furnace wall according to the furnace dimensions, and try to ensure that the spraying is carried out at a 90° angle to the furnace wall. Close attention should be paid to the main parameters of the three elements of material, accelerator and air during the spraying process: under normal circumstances, the liquid amount of accelerator should be controlled at 1 to 2% (adjusted according to the on-site temperature and other conditions) to ensure that there is no peeling, loosening and cracking after spraying, and the discharge rate should be controlled at about 80-100 kg / min. 3) The sprayer should adjust the position in a timely manner according to the discharge speed to ensure the flatness of the spray. The surface after spraying should be flat and smooth with uniform thickness. The flatness should be controlled within 10mm, the thickness deviation of the spray should not be greater than ±10mm, and there should be no voids in the spray layer to meet the requirements of the furnace type.

[0010] Preferably, after the spraying in step S3 is completed and passes inspection, the spraying equipment is hoisted and dismantled along the original route.

[0011] Preferably, in step S4, the temperature is increased according to the preset furnace baking curve: from room temperature to 150℃ for 12 hours (rate 11℃ / h), and held at 150℃ for 36 hours; from 150℃ to 350℃ for 12 hours (rate 17℃ / h), and held at 350℃ for 12 hours; from 350℃ to 550℃ for 12 hours (rate 17℃ / h), and held at 550℃ for 36 hours. The temperature deviation is controlled within ±5℃ or ±20℃. During furnace baking, the temperature of the thermocouples inside the furnace is the main control, and the hot air temperature is the auxiliary control. The furnace top temperature is strictly controlled to avoid rapid cooling and heating.

[0012] Compared with the prior art, the present invention provides a preparation method and construction method of silicon carbide composite refractory material for wet injection of blast furnace lining, which has the following beneficial effects: 1. High adhesion and anti-detachment properties: The use of a silica sol bonding system significantly enhances the adhesion between the material and the old lining, effectively preventing detachment during use; 2. Low porosity and high density: By optimizing the particle size distribution and introducing active micro powder, the material has low porosity, strong resistance to penetration and erosion, and can resist furnace material wear, gas erosion and alkali metal corrosion. 3. Rapid slagging and self-protection: The material has excellent thermal conductivity and can quickly form a slag skin in blast furnace operation, which can achieve self-protection of blast furnace equipment and help the blast furnace to operate for a long time. 4. Environmentally friendly construction characteristics: The injection process generates no dust or toxic gases, has a low construction rebound rate, does not affect the operation of the blast furnace TRT, and meets environmental protection requirements; 5. Long life and high efficiency: It can quickly restore the blast furnace shape, shorten the downtime for repair, increase blast furnace output, reduce energy consumption, and significantly extend the service life of the blast furnace. Attached Figure Description

[0013] Figure 1 This is an explanation of the oven drying curve for the present invention; Figure 2 This is a schematic diagram of the spray lining construction process of the present invention. Detailed Implementation

[0014] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0015] Example 1: 4747m 3 Blast furnace body injection The silicon carbide composite refractory sprayed material prepared by the method of this invention was applied to a 4747m² application site according to the above construction method. 3 The blast furnace body underwent a material drop line injection construction. During the injection process, the material rebound rate was ≤5%, the injection layer thickness was uniform, and the overall integrity was good. The blast furnace resumed production 2 days after the injection was completed. During the resumption period, the blast temperature was maintained at 1190~1235℃, the oxygen enrichment was 3.5%~6.7%, and there was no detachment of the injection layer during operation. There were no hot spots in the furnace shell, and the blast furnace continued to operate stably.

[0016] Example 2: Sintering machine flue gas injection Anchors are welded to the inner wall of the flue shell and a metal mesh is arranged. The injection material prepared in this invention is used for mechanical injection construction to form an integral lining structure. This lining has excellent acid and wear resistance. Actual operation has verified that its service life is more than 3 times longer than that of traditional injection material linings.

[0017] In summary, the preparation and construction method of the silicon carbide composite refractory material for wet injection into blast furnace linings, through the synergistic design of precise proportioning of high-quality components, scientific optimization of the preparation process, and precise construction control, and by employing high-pressure furnace washing, precise injection parameters, and scientific furnace drying curves during construction, ensures that the silicon carbide composite refractory material possesses the compositional characteristics of Al2O3≥70%, SiC≥13%, CaO≤0.5%, and a bulk density≥2.85g / cm³. 3 It has a flexural strength ≥12MPa, a compressive strength ≥80MPa, a linear change rate after firing ±0.5%, and a construction rebound rate ≤5%. It combines the advantages of high adhesion and anti-detachment properties, low porosity and high density, rapid slagging and self-protection, environmentally friendly construction characteristics, long service life and high efficiency.

[0018] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for preparing silicon carbide composite refractory material for wet injection into blast furnace linings, characterized in that, Includes the following steps: S1. Raw material selection and pretreatment: Selected low-alkali bauxite clinker, dense fused alumina, mullite, silicon carbide and high-alumina microcrystalline ceramics from Shanxi Province are crushed and screened respectively, and the particle size distribution is controlled to achieve the densest packing. Stable zirconia ZrO2 is selected as the reinforcing phase for later use. S2. Preparation of micro powder and reinforcing phase: Dense fused alumina is ultra-finely ground to 800 mesh to obtain fused alumina micro powder, silicon carbide is ultra-finely pulverized to 800 mesh and stored for later use, and stabilized zirconium oxide ZrO2 is ultra-finely pulverized to 2000 mesh and stored separately for later use. S3. Ingredients: By mass percentage, the raw material composition is as follows: 40% Shanxi low-alkali bauxite clinker, 20% dense fused alumina, 15% mullite, 10% silicon carbide, 5% silicon carbide, 8% high-alumina microcrystalline ceramic, 0.5~1.5% fused alumina powder, and 0.5~1% zirconium oxide; S4. Dry mixing: The aggregates of each grade in step S3, along with the micro powder and zirconium oxide reinforcing phase, are put into a high-efficiency forced mixer for dry mixing. S5. Adding binder: After dry mixing is even, slowly add silica sol binder and coagulant accelerator and continue stirring to form a uniform wet mixture; S6. Wet mixing and adjustment: Add an appropriate amount of water to adjust the fluidity of the slurry according to the state of the wet mixture, control the viscosity required for construction, and the finished sprayable material is obtained after mixing. S7. Quality Control: Take a small amount of the finished sprayed material, dry and bake it, and then take samples to test its physicochemical properties.

2. The method for preparing silicon carbide composite refractory material for wet injection into blast furnace lining according to claim 1, characterized in that, 800-mesh fused alumina powder can improve the sintering activity and flowability of materials.

3. The method for preparing silicon carbide composite refractory material for wet injection into blast furnace lining according to claim 1, characterized in that, Step S4: Dry mix for 10–15 minutes, until the color is uniform and there are no clumps.

4. The method for preparing silicon carbide composite refractory material for wet injection into blast furnace lining according to claim 1, characterized in that, After adding the silica sol binder and coagulant in step S5, continue stirring for 5–8 minutes to ensure that the binder fully coats the particle surface and forms a uniform wet mixture.

5. The method for preparing silicon carbide composite refractory material for wet injection into blast furnace lining according to claim 1, characterized in that, Step S7: The physicochemical properties of the finished sprayed refractory must meet the following requirements: Al2O3 ≥ 70%, SiC ≥ 13%, CaO ≤ 0.5%, and bulk density ≥ 2.85 g / cm³. 3 Flexural strength ≥12MPa, compressive strength ≥80MPa, linear change rate after firing ±0.5%, construction rebound rate ≤5%.

6. A construction method for wet injection of silicon carbide composite refractory material for blast furnace lining, characterized in that, The injection material obtained by the preparation method according to any one of claims 1-5 includes the following steps: S1, Cleaning the furnace; S2, In-furnace injection; S3. Remove the spraying equipment; S4, Oven.

7. The construction method for wet-sprayed silicon carbide composite refractory material for blast furnace lining according to claim 6, characterized in that, In step S1, high-pressure atomized water at a pressure of 30MPa and a flow rate of ≤1 ton per hour is used to clean the residual furnace lining, loose material, and dust inside the furnace twice, from top to bottom and then from bottom to top.

8. The construction method for wet injection of silicon carbide composite refractory material for blast furnace lining according to claim 6, characterized in that, In step S2, before spraying, check and open the tuyeres and manholes of the gas hood to ensure air circulation. The newly formed furnace lining must meet the furnace size requirements, have a smooth surface, and the spraying thickness must be controlled within the required range. Construction is carried out according to the thickness requirements of different parts. For the furnace belly, furnace waist, and the lower 7-12 sections of the copper cooling wall dovetail grooves, sprayed refractory is used. The hot surface of the furnace belly and furnace waist is sprayed 60mm, the lower part of the furnace body is sprayed 20mm, the ductile iron cooling wall bricks in sections 12, 13, and 14 of the middle furnace body are 20mm thick, and the dovetail grooves of the upper 15-17 sections of the ductile iron cooling wall are sprayed refractory, with a 50mm spray thickness on the hot surface. A smooth transition from the furnace belly to the hot surface of the furnace body cooling wall is ensured. To guarantee the best spraying effect, the following technical measures are taken: 1) Based on the inner diameter of each part, the injection operator adjusts the position and angle according to the distance from the wall. During the injection process, the air pressure and air volume, the discharge volume and the amount of accelerator added are all adjusted in a timely manner according to the actual situation to ensure that the rebound of the blast furnace injection is minimized. 2) Depending on the different parts of the furnace lining to be sprayed, the sprayer should select the distance and angle between the sprayer and the furnace wall according to the furnace dimensions, and try to ensure that the spraying is carried out at a 90° angle to the furnace wall. Close attention should be paid to the main parameters of the three elements of material, accelerator and air during the spraying process: under normal circumstances, the liquid amount of accelerator should be controlled at 1 to 2% to ensure that there is no peeling, loosening and cracking after spraying, and the discharge rate should be controlled at about 80-100 kg / min. 3) The sprayer should adjust the position in a timely manner according to the discharge speed to ensure the flatness of the spray. The surface after spraying should be flat and smooth with uniform thickness. The flatness should be controlled within 10mm, the thickness deviation of the spray should not be greater than ±10mm, and there should be no voids in the spray layer to meet the requirements of the furnace type.

9. The construction method for wet injection of silicon carbide composite refractory material for blast furnace lining according to claim 6, characterized in that, In step S3, after the spraying is completed and passes inspection, the spraying equipment is hoisted and dismantled along the original route.

10. The construction method of silicon carbide composite refractory material for wet injection into blast furnace lining according to claim 6, characterized in that, In step S4, the temperature is increased according to the preset furnace baking curve: from room temperature to 150℃ for 12 hours, and then held at 150℃ for 36 hours; from 150℃ to 350℃ for 12 hours, and then held at 350℃ for 12 hours; from 350℃ to 550℃ for 12 hours, and then held at 550℃ for 36 hours. The temperature deviation is controlled within ±5℃ or ±20℃. During furnace baking, the temperature of the thermocouples inside the furnace is the primary control, and the temperature of the hot air is secondary. The temperature of the furnace top is strictly controlled to avoid rapid cooling and heating.

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