Carbon mud for carbon brick masonry as well as preparation method and application of carbon mud

Abstract

The invention discloses carbon mud for carbon brick masonry as well as a preparation method and application thereof, and belongs to the technical field of refractory materials. The carbon mud comprises the following raw materials in percentage by mass: 33-55% of graphite particles, 30-50% of graphite powder, 5-10% of waste silicon carbide refractory slab powder, 2-4% of boric acid, 0.5-2% of a defoaming agent, 2-4% of white carbon black and 3-6% of aluminum micro powder. Furan resin accounting for 48-60% of the total mass of the raw material components is added. The carbon mud finished product is supplied without precipitation and layering, can be used after being directly unpacked, is not easy to flow, is fully filled in brick joints, has higher heat conductivity coefficient and bonding strength, effectively resists scouring, erosion and permeation at high temperature, ensures smooth heat conduction of a blast furnace, and prolongs the service life of the blast furnace; the preparation is simple, raw materials are cheap, and industrial application is facilitated.

Description

Technical Field

[0001] This invention belongs to the field of refractory materials technology, specifically relating to a carbon mortar for carbon brick masonry, its preparation method, and its application. Background Technology

[0002] Blast furnaces are critical equipment in steel production. The furnace bottom must withstand high temperatures, high pressures, and the erosion and penetration of slag and iron. These harsh working conditions place extremely high demands on the lining materials of the blast furnace bottom. The carbon bricks used for blast furnace bottom lining, constructed with carbon mortar, must also possess excellent high-temperature resistance, erosion resistance, and thermal conductivity. During the lining process, the mortar must be fully filled to bond the carbon bricks into a unified whole, improving the integrity and compactness of the lining and ensuring that the carbon bricks do not separate or fall off. High thermal conductivity allows heat to be rapidly transferred between the carbon bricks and the mortar to the cooling system. Furthermore, the mortar effectively resists the erosion, penetration, and erosion of slag and molten iron within the blast furnace, ensuring the normal operation and service life of the blast furnace. However, in practical applications, carbon mortar suffers from problems such as incomplete filling, easy flow, low bonding strength at high temperatures, poor erosion and penetration resistance, and low thermal conductivity. High-temperature molten slag and iron easily erode and penetrate into the carbon brick joints, causing the carbon bricks to fall off, expand, and crack, affecting heat transfer at the furnace bottom and thus impacting the service life of the blast furnace bottom lining material. Summary of the Invention

[0003] The purpose of this invention is to provide a carbon slurry for blast furnace carbon brick lining, its preparation method and application. The carbon slurry is supplied as a finished product, does not settle or separate, and can be used directly after unpacking. The slurry does not easily flow, and the slurry fills the brick joints fully. It has a high thermal conductivity and bonding strength, effectively resists erosion and penetration at high temperatures, ensures smooth heat conduction in the blast furnace, and extends the service life of the blast furnace.

[0004] To achieve the above objectives, the following technical solution is adopted: A carbon slurry for blast furnace carbon brick lining is provided, comprising, by mass percentage: 33-55% graphite particles, 30-50% graphite powder, 5-10% waste silicon carbide shed board powder, 2-4% boric acid, 0.5-2% defoamer, 2-4% silica, and 3-6% aluminum powder; Add 48-60% of the total mass of the above raw material components to furan resin.

[0005] According to the above scheme, the particle size of the graphite particles is 0~0.3mm.

[0006] According to the above scheme, the particle size of the graphite powder is 0~0.088mm.

[0007] According to the above scheme, the graphite particles and graphite powder are made from crushed waste electrodes.

[0008] According to the above scheme, the graphite powder contains C ≥ 98wt% and ash content ≤ 0.4wt%.

[0009] According to the above scheme, the waste silicon carbide shed powder contains SiC ≥ 75wt%, free Si ≥ 10wt%, and particle size of 0~0.088mm.

[0010] According to the above scheme, the waste silicon carbide sintering plate powder is silicon carbide sintering plate waste produced using reaction-sintered silicon carbide as raw material.

[0011] According to the above scheme, the defoamer is an organosilicon polyurethane, a transparent liquid with a pH value of 5-8 and a solid content of 66-99%.

[0012] According to the above scheme, the silica is hydrophobic with an average particle size of 10-15 nm. Preferably, SiO2 ≥ 99 wt%.

[0013] According to the above scheme, the Al2O3 content in the aluminum micropowder is ≥99%, D 50 ≤1.5μm.

[0014] According to the above scheme, the thermal conductivity of the carbon slurry is 9~12W / (m·K), and the flexural bonding strength after calcination at 1200℃ is 7~11MPa.

[0015] According to the above scheme, the carbon mud will not separate into layers after being stored for more than six months.

[0016] A method for preparing the above-mentioned carbon slurry for blast furnace carbon brick lining is provided, comprising the following steps: 1) Mix precipitated silica and 1 / 5 to 1 / 3 of the mass of furan resin and stir at high speed to disperse evenly; 2) Mix the graphite particles, graphite powder, waste silicon carbide shed powder, boric acid, defoamer, aluminum micro powder and remaining furan resin and stir evenly; 3) Gradually add the mixed solution obtained in step 1) to the mixed solution obtained in step 2), and stir evenly to obtain carbon slurry for blast furnace carbon brick lining.

[0017] According to the above scheme, in step 1), the high-speed stirring rate is 6~8m / s, the stirring time is 20~30min, and the stirring temperature is 40~45℃.

[0018] According to the above scheme, in step 2), the stirring time is 5~8 minutes.

[0019] According to the above scheme, in step 3), the stirring time is 10~15min.

[0020] According to the above scheme, in step 3), the carbon mud obtained is stored for more than six months without separation.

[0021] Ironmaking in the blast furnace hearth primarily utilizes the high temperature and reducing atmosphere generated by coke combustion to reduce iron ore to elemental iron. However, after coke combustion consumes oxygen, a large amount of nitrogen remains inside the furnace. Therefore, the blast furnace hearth atmosphere includes both nitrogen and a reducing atmosphere. In this invention, the boric acid in the carbon slurry used for blast furnace carbon brick lining decomposes into boron oxide upon heating. Under the high-temperature reducing atmosphere of the blast furnace hearth, most of the boron oxide undergoes a reduction reaction with an abundant carbon source (excess carbon) at high temperatures (1000~1300℃) to generate amorphous boron. This amorphous boron then reacts with the inert nitrogen in the blast furnace to generate in-situ boron nitride (BN), filling the pores in the material, increasing its hardness, and making the slurry more resistant to erosion. Simultaneously, a small amount of boron oxide also promotes the sintering mullite reaction of nano-SiO2 (white carbon black) and aluminum micropowder, significantly improving the overall bonding strength and structural density of the slurry, further enhancing its resistance to slag-iron erosion. The in-situ generated plate-like or fibrous BN crystals grow interlaced along the gaps between silicon carbide and mullite crystals generated in the waste silicon carbide shed powder, forming a continuous and dense embedded composite anti-seepage and thermally conductive coating with high interfacial bonding energy and no obvious interfacial gaps. At the same time, boron nitride has good thermal conductivity and poor wettability to molten slag iron, which further effectively blocks the penetration and erosion of blast furnace slag iron, while improving the thermal conductivity of the mud.

[0022] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. This invention provides a carbon slurry for blast furnace carbon brick lining, with graphite particles and graphite powder as the main heat-conducting components and inexpensive and readily available boric acid as the boron source. Based on the nitrogen and reducing atmosphere in the blast furnace hearth, boron oxide is generated, and most of the boron oxide is then converted into boron nitride (BN) in situ. On the one hand, a small amount of boron oxide can promote the sintering mullite reaction of silica nano-SiO2 and aluminum micropowder; on the other hand, the BN crystals generated in situ grow interlaced along the gaps between silicon carbide and the reacted mullite crystals, forming a continuous and dense embedded structure. A composite seepage-proof and thermally conductive coating, combined with a defoamer to reduce air bubbles in the viscous slurry, further improves the thermal conductivity of the slurry. Simultaneously, the synergistic effect of nano-grade silica promotes the uniformity and stability of the slurry. The resulting carbon slurry can be supplied as a finished product, exhibiting no sedimentation or stratification for over six months. It can be used directly after unpacking, is not prone to flow, and fills brick joints fully. It also possesses high thermal conductivity and bonding strength, effectively resisting erosion and penetration at high temperatures, ensuring smooth heat transfer in the blast furnace, extending its service life, and demonstrating broad application prospects.

[0023] 2. This invention uses waste silicon carbide shed powder as raw material, and graphite particles and graphite powder are made from waste electrode crushing materials, realizing the recycling of industrial solid waste. In addition, it uses inexpensive and readily available boric acid, which significantly reduces the cost of raw materials.

[0024] 3. This invention provides a method for preparing the above-mentioned carbon slurry. First, precipitated silica is dispersed evenly in a portion of furan resin by high-speed stirring, laying the foundation for the uniformity and stability of the slurry. The remaining raw materials are mixed and stirred evenly with the remaining furan resin. The mixture of the two yields a uniform and stable carbon slurry. The preparation is simple, the production is stable, and it is conducive to industrial application. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0026] The raw materials used in the specific embodiments meet the following requirements: The graphite particles are made from crushed waste electrodes, with a particle size of 0~0.3mm.

[0027] The graphite powder is made from crushed waste electrodes and meets the following requirements: C ≥ 98wt%, ash content ≤ 0.4wt%, and particle size 0~0.088mm.

[0028] Waste silicon carbide sintering plate powder is silicon carbide sintering plate waste produced using reaction-sintered silicon carbide as raw material, with SiC≥75wt%, free Si≥10wt%, and particle size of 0~0.088mm.

[0029] The defoamer is an organosilicon polyurethane, a transparent liquid with a pH value of 5-8 and a solid content of 66-99%.

[0030] The silica is hydrophobic, with SiO2 ≥ 99wt% and an average particle size of 14nm.

[0031] In aluminum micro powder, the Al2O3 content is ≥99%, D 50 ≤1.5μm.

[0032] The preparation method of carbon mud in the following embodiment includes the following steps: 1) Add the silica to the mixing equipment and add 1 / 3 of the mass of furan resin. Start high-speed mixing and dispersion. The mixing line speed is 6 m / s, the mixing time is 20 min, and the mixing temperature is 45℃.

[0033] 2) Mix graphite particles, graphite powder, waste silicon carbide shed powder, boric acid, defoamer and aluminum micro powder and add them to the remaining 2 / 3 of furan resin and stir evenly for 5 minutes.

[0034] 3) Slowly add the mixture from step 1 to the mixture from step 2, mix well and stir for 10 minutes to obtain carbon slurry for blast furnace carbon brick lining. Seal it in a metal bucket. When constructing, open the bucket and use it directly. The operation is convenient.

[0035] Example 1 A carbonaceous slurry for blast furnace carbon brick lining is provided, the composition of which, by mass percentage, is: Graphite particles 33%, graphite powder 46%, waste silicon carbide shed board powder 8%, boric acid 3%, defoamer 1%, precipitated silica 3%, aluminum micro powder 6%; 51.3wt% furan resin was added externally.

[0036] Testing showed that the obtained carbon slurry did not separate or stratify after 6 months of storage, indicating good construction conditions. The slurry's thermal conductivity at 200℃ was 10.2 W / (m·K), meeting the heat transfer requirements of the blast furnace hearth. After calcination at 1200℃, its flexural bond strength was 8.9 MPa.

[0037] Example 2 A carbonaceous slurry for blast furnace carbon brick lining is provided, the composition of which, by mass percentage, is: Graphite granules 37%, graphite powder 50%, waste silicon carbide shed board powder 5%, boric acid 2%, defoamer 0.7%, silica 2%, aluminum powder 3.3%; 58.2 wt% furan resin was added externally.

[0038] Testing showed that the obtained carbon slurry did not separate or stratify after 6 months of storage, indicating good construction conditions. The slurry's thermal conductivity at 200℃ was 9.3 W / (m·K), meeting the heat transfer requirements of the blast furnace hearth. After calcination at 1200℃, its flexural bond strength was 7.2 MPa.

[0039] Example 3 A carbonaceous slurry for blast furnace carbon brick lining is provided, the composition of which, by mass percentage, is: Graphite particles 41%, graphite powder 33%, waste silicon carbide shed board powder 10%, boric acid 4%, defoamer 2%, precipitated silica 4%, aluminum micro powder 6%; 49.5 wt% furan resin was added externally.

[0040] Testing showed that the obtained carbon slurry did not separate or stratify after 6 months of storage, indicating good construction conditions. The slurry's thermal conductivity at 200℃ was 11.4 W / (m·K), meeting the heat transfer requirements of the blast furnace hearth. After calcination at 1200℃, its flexural bond strength was 10.8 MPa.

[0041] Example 4 A carbonaceous slurry for blast furnace carbon brick lining is provided, the composition of which, by mass percentage, is: Graphite particles 47%, graphite powder 36.4%, waste silicon carbide shed board powder 6%, boric acid 3%, defoamer 1.6%, precipitated silica 2%, aluminum micro powder 4%; 53.6 wt% furan resin was added externally.

[0042] Testing showed that the obtained carbon slurry did not separate or stratify after 6 months of storage, indicating good construction conditions. The slurry's thermal conductivity at 200℃ was 10.4 W / (m·K), meeting the heat transfer requirements of the blast furnace hearth. After calcination at 1200℃, its flexural bond strength was 8.3 MPa.

[0043] Example 5 A carbonaceous slurry for blast furnace carbon brick lining is provided, the composition of which, by mass percentage, is: Graphite granules 53%, graphite powder 31%, waste silicon carbide slab powder 5%, boric acid 4%, defoamer 0.5%, silica 3%, aluminum powder 3.5%; 54.3 wt% furan resin was added externally.

[0044] Testing showed that the obtained carbon mud did not separate or stratify after 6 months of storage, indicating good construction conditions. The thermal conductivity of the mud at 200℃ was 9.6 W / (m·K), meeting the heat transfer requirements of the blast furnace hearth. After calcination at 1200℃, the flexural bond strength was 7.8 MPa.

[0045] Obviously, the above embodiments are merely examples for clear illustration and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations, and any obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A carbon slurry for blast furnace carbon brick lining, characterized in that, The raw materials of the carbon slurry, by weight percentage, include: 33-55% graphite particles, 30-50% graphite powder, 5-10% waste silicon carbide shed board powder, 2-4% boric acid, 0.5-2% defoamer, 2-4% silica, and 3-6% aluminum powder; Add 48-60% of the total mass of the above raw material components to furan resin.

2. The carbonaceous slurry according to claim 1, characterized in that, The graphite particles have a particle size of 0~0.3mm; the graphite powder has a particle size of 0~0.088mm.

3. The carbonaceous slurry according to claim 1, characterized in that, The graphite particles and graphite powder are produced using waste electricity. Extremely crushed materials.

4. The carbonaceous slurry according to claim 1, characterized in that, The waste silicon carbide shed powder contains SiC ≥ 75wt%, free Si ≥ 10wt%, and a particle size of 0~0.088mm; the silica is hydrophobic with an average particle size of 10~15nm.

5. The carbonaceous slurry according to claim 1, characterized in that, The defoamer is an organosilicon polyurethane, a transparent liquid with a pH of 5-8 and a solid content of 66-99%; the aluminum micropowder contains ≥99% Al2O3 and D... 50 ≤1.5μm.

6. The carbonaceous slurry according to claim 1, characterized in that, The thermal conductivity of the carbon slurry is 9~12 W / (m·K), and its flexural bonding strength after calcination at 1200℃ is 7~11 MPa.

7. The carbonaceous slurry according to claim 1, characterized in that, The carbon mud does not separate into layers after being stored for more than six months.

8. A method for preparing carbon slurry for blast furnace carbon brick lining as described in any one of claims 1-7, characterized in that, Includes the following steps: 1) Mix precipitated silica and 1 / 5 to 1 / 3 of the mass of furan resin and stir at high speed to disperse evenly; 2) Mix the graphite particles, graphite powder, waste silicon carbide shed powder, boric acid, defoamer, aluminum micro powder and remaining furan resin and stir evenly; 3) Gradually add the mixed solution obtained in step 1) to the mixed solution obtained in step 2), and stir evenly to obtain carbon slurry for blast furnace carbon brick lining.

9. The preparation method according to claim 8, characterized in that, In step 1), the high-speed stirring rate is 6~8m / s, the stirring time is 20~30min, and the stirring temperature is 40~45℃.

10. The application of the carbon slurry according to any one of claims 1-7 in the construction of carbon bricks in blast furnaces.