Blast furnace integrated in-situ lining-making corundum-silicon carbide new material system and lining-making process

Abstract

The invention relates to the technical field of blast furnace lining making processes, and discloses a blast furnace integrated in-situ lining making corundum-silicon carbide new material system and a lining making process, and the blast furnace integrated in-situ lining making corundum-silicon carbide new material system comprises a furnace bottom and hearth temperature field distribution physical model, a mathematical model and boundary conditions Gamma1-Gamma6 which are obtained by simulating blast furnace body temperature field and pressure field distribution through finite element analysis. The method has the advantages that according to failure mechanisms of refractory materials in different areas, the hearth structure is integrally optimized, and the optimal pouring material selection is obtained through digital simulation, so that the blast furnace construction time can be greatly shortened, and integrated full-furnace pouring of the blast furnace lining is realized; according to refractory material configuration for whole-furnace pouring, whole-furnace formwork erecting and pouring are directly conducted in the furnace by clinging to furnace bottom carbon bricks, annular carbon, iron notches and cooling walls, then the working procedures of maintenance, formwork removal, furnace baking and the like are conducted, one-time forming is achieved, only baking is needed for whole-furnace pouring, the high-temperature firing process is not needed, the advantages of being simple in process, energy-saving and environment-friendly are achieved, and the service life of the blast furnace can be greatly prolonged.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of blast furnace lining construction process, in particular to a blast furnace integrated in-situ lining corundum-silicon carbide new material system and lining construction process. BACKGROUND

[0002] The blast furnace body is divided into five parts from top to bottom, namely, the furnace throat, the furnace shaft, the furnace waist, the furnace bosh and the furnace hearth. The temperature of each part is as follows: the furnace bottom is generally 1450-1500℃, the furnace hearth part, especially the tuyere area, is 1700-2000℃, the furnace bosh and the furnace waist area is 1400-1600℃, and the upper part of the furnace shaft is 600-800℃. During the production of the blast furnace, iron ore, coke and flux (limestone) for slagging are loaded from the top of the furnace, and preheated air is blown into the tuyere located at the lower part of the furnace along the circumference of the furnace. At high temperature, coke (some blast furnaces also spray coal powder, heavy oil, natural gas and other auxiliary fuels) burns with oxygen in the air to generate carbon monoxide and hydrogen, which reduces iron ore to iron during the ascending process in the furnace.

[0003] In the development history of blast furnaces, the design concept of the furnace bottom and the furnace hearth has undergone several innovations. In the 1960s, the lining of the blast furnace bottom and the furnace hearth was mainly composed of clay bricks and high alumina bricks, which was called "white bottom". However, the actual use effect was not ideal. In the process of gradually studying the damage mechanism of the furnace bottom and the furnace hearth, it was found that if the lining of the furnace bottom and the furnace hearth could be kept at a relatively low temperature range, the erosion could be effectively slowed down or inhibited, and the service life of the furnace bottom and the furnace hearth could be prolonged.

[0004] According to current research reports, most of the research work on blast furnace lining materials and lining construction process is focused on the optimization of the structure of the existing ceramic cup for the furnace hearth and the carbon brick for the furnace bottom, and the improvement of the material thermal conductivity coefficient and the erosion resistance through structural design. However, since the material quality and the laying method of the blast furnace lining have not changed, although the service performance has been improved, it is still impossible to realize the long service life of large blast furnaces. Due to the advantages of short production cycle, high construction efficiency, strong adaptability, convenient laying of complex shaped lining, good overall performance of the furnace lining, etc., refractory castables have gradually attracted attention in the field of high temperature and harsh service environment. In fact, if the refractory used for integrated full-furnace casting is all unshaped refractory, replacing the traditional blast furnace lining made of shaped refractory, it is expected to greatly reduce the cost and prolong the service life of the lining of large blast furnaces. However, so far, there is no relevant report at home and abroad, therefore, it is urgent to develop a new technology of refractory castable and integrated casting for the furnace hearth and the furnace bottom and the tuyere area of the blast furnace, which is easy to construct and has long service life.

[0005] To solve the above problems, the present application provides a blast furnace integrated in-situ lining corundum-silicon carbide new material system and lining construction process. SUMMARY

[0006] The technical problems solved by the present application

[0007] In view of the deficiencies of the prior art, the present application provides a blast furnace integrated in-situ lining-making corundum-silicon carbide new material system and a lining-making process, which has the advantages of short manufacturing period and long service life, and solves the problem of long manufacturing period of traditional blast furnaces.

[0008] The technical solutions

[0009] To achieve the above-mentioned short manufacturing period and long service life, the present application provides the following technical solutions: a blast furnace integrated in-situ lining-making corundum-silicon carbide new material system and a lining-making process, which comprises a furnace bottom and furnace shell temperature field distribution physical model, a mathematical model and boundary conditions Γ1 to Γ6 obtained by simulating the temperature field and pressure field distribution of the blast furnace body through finite element analysis, and the conditions of each boundary of Γ1 to Γ6 are as follows:

[0010] Γ1 boundary is the center line boundary of the furnace shell, and this boundary has no heat transfer and is regarded as an adiabatic boundary.

[0011] Γ2 boundary is close to the furnace bottom cooling system and is the outer boundary of the entire system, and is regarded as a convection boundary.

[0012] Γ3 boundary is close to the furnace shell cooling system and is the outer boundary of the entire system, and is regarded as a convection boundary.

[0013] Γ4 boundary is regarded as an adiabatic boundary because the heat flow in the furnace mainly flows in the r direction.

[0014] Γ5 boundary is the erosion boundary of molten iron and furnace lining refractory material, and the temperature field of this boundary and the surrounding area is simulated and calculated.

[0015] Γ6 boundary is the upper surface of the molten iron, and since the hot molten iron continuously drips from the soft melting layer to the furnace shell during the operation of the blast furnace, this boundary is regarded as a constant temperature boundary.

[0016] Preferably, 1-3 typical blast furnaces are selected for geometric modeling, and ten regions are divided according to different lining materials, the temperature field changes are analyzed by changing the thermal performance parameters of the materials in each region, the material properties of different refractory linings required in each region of the model are solved by using the ANSYS software Fluent solver, iterative simulation calculation is performed, and the operation results are post-processed and output temperature field distribution map by using the Result module.

[0017] Preferably, based on the Al2O3-SiC phase diagram, the influences of the particle size and proportion of dense corundum and silicon carbide, nano-composite binder, calcium carbonate cement, Guangxi white clay, alumina micropowder, silica micropowder, sodium tripolyphosphate and nano-silica sol particle size and addition amount on the physical and chemical properties (bulk density, porosity and bending strength) of the green body of the castable are studied, the influences of high-temperature sintering temperature and holding time on the microstructure, pore structure, mechanical properties, erosion resistance and thermal conductivity of the material are studied, and the optimal preparation conditions of the micro-nano combined Al2O3-SiC castable for the hearth are obtained.

[0018] Preferably, high-titanium ore or titanium dioxide TiO2 is added in the Al2O3-SiC castable in the initial stage of the high in-situ furnace operation, and the TiC(N) generated in the special reducing atmosphere of the blast furnace further improves the slag erosion resistance of the castable for the hearth and tuyere.

[0019] Preferably, based on the orthogonal test design and analysis method, the influences of the particle size and proportion of brown corundum and silicon carbide, calcium carbonate cement, alumina micropowder, silica micropowder, flint, sodium tripolyphosphate, spherical pitch and zirconia addition amount on the physical and chemical properties (bulk density, porosity and bending strength) of the green body of the castable are studied, the influences of high-temperature sintering temperature and holding time on the microstructure, pore structure, mechanical properties, erosion resistance and thermal conductivity of the material are studied, and the optimal preparation conditions of the ZrO2 composite Al2O3-SiC-C castable for the iron notch area are obtained.

[0020] Preferably, the expansion coefficients of the castables are calculated, and expansion joints are reserved; the above-prepared micro-nano combined Al2O3-SiC castable, titanium-modified Al2O3-SiC refractory castable, Sialon reinforced corundum-silicon carbide-mullite gunning material and other supporting materials prepared by the enterprise are integrally cast in the blast furnace, and then curing, form removal, furnace baking and other processes are performed.

[0021] (Three) beneficial effects

[0022] Compared with the prior art, the present application provides a new material system and lining making process for the blast furnace integration in-situ lining making, and has the following beneficial effects:

[0023] This invention utilizes finite element analysis to simulate the temperature and pressure field distribution of the blast furnace hearth, a key component, to obtain physical and mathematical models of the hearth temperature field distribution, as well as boundary conditions. Firstly, by calculating and simulating the temperature field distribution within the blast furnace and the failure mechanisms of refractory materials in different regions, the overall hearth structure is optimized. Based on its structural characteristics, the optimal casting material selection is determined through digital simulation. This significantly shortens blast furnace construction time. Furthermore, the integrated casting process uses only unshaped refractories, enabling integrated casting of the blast furnace lining, replacing the traditional blast furnace lining constructed with shaped refractories. The refractory configuration for the integrated casting involves directly casting the entire furnace within the furnace, adhering to the bottom carbon bricks, ring carbon, taphole, and cooling walls. Curing, demolding, and furnace drying are then performed in a single process. The entire furnace casting only requires baking, eliminating the need for high-temperature firing processes. This offers advantages such as simple technology, energy saving, and environmental friendliness, resulting in a more uniform structure and significantly extending the blast furnace's service life. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the longitudinal section and boundary conditions of the furnace bottom and hearth region proposed in this invention.

[0025] In the diagram: 1. Molten iron containment area; 2. Hearth refractory material. Detailed Implementation

[0026] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. 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 skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] like Figure 1 As shown, the integrated in-situ lining system of corundum-silicon carbide for blast furnaces and the lining process include the physical model, mathematical model, and boundary conditions Γ1 to Γ6 of the temperature field distribution of the hearth and furnace bottom obtained by finite element analysis simulating the temperature and pressure field distribution of the blast furnace body. The conditions of each boundary from Γ1 to Γ6 are as follows:

[0028] The Γ1 boundary is the centerline boundary of the furnace hearth. There is no heat transfer at this boundary, so it is considered an adiabatic boundary.

[0029] The Γ2 boundary is close to the furnace bottom cooling system and is the outer boundary of the entire system, and is regarded as the convection boundary.

[0030] The Γ3 boundary is close to the furnace hearth cooling system and is the outer boundary of the entire system, and is regarded as a convective boundary.

[0031] Since the heat flow inside the furnace mainly flows along the r direction, the Γ4 boundary is considered an adiabatic boundary.

[0032] Γ5 is the interface between hot metal and refractory lining, the temperature field of this interface and its surrounding area is simulated.

[0033] Γ6 is the upper surface of hot metal, which is considered as constant temperature boundary, because the hot metal continuously drips from the softening layer to the hearth during the blast furnace operation.

[0034] Based on numerical simulation, the temperature field and pressure field of blast furnace body are constructed, the essential relationship between heat transfer and slag-iron protective layer is revealed, and the mechanism and law of heat balance and hearth safety and long life are clarified.

[0035] The geometric modeling of 1-3 typical blast furnaces is selected, and ten regions are divided according to different lining materials. The temperature field changes are analyzed by changing the thermal performance parameters of each region material. The material performance of different refractory lining in each region of the model is calculated by using the Fluent solver of ANSYS software, and the Result module is used for post-processing and outputting the temperature field distribution graph. The temperature field distribution of the hearth under different refractory material configuration conditions is calculated by the finite element simulation method, the failure mechanism of refractory materials in different regions is discussed, the formation conditions of the "softening layer" of hot metal are explored, and the direction of research and development of advanced composite new material system is clarified.

[0036] Based on the Al2O3-SiC phase diagram, the orthogonal test design and optimization analysis method are used to study the influence of dense corundum, silicon carbide particle size and ratio, nano composite binder, calcium carbonate cement, Guangxi white clay, alumina powder, silicon powder, sodium tripolyphosphate and nano silica sol particle size and addition amount on the physical and chemical properties of green body (bulk density, porosity and bending strength) of castable. The influence of high temperature sintering temperature and holding time on the microstructure, pore structure, mechanical properties, erosion resistance and thermal conductivity of the material is studied, and the optimal preparation conditions of the micro-nano combined Al2O3-SiC castable for the hearth are obtained. Based on the service conditions of the hearth, the bottom, the tuyere and the iron notch, and based on the research and development idea of high thermal conductivity castable for the hearth, the micro-nano combined Al2O3-SiC castable for the blast furnace hearth, the oxide modified Al2O3-SiC castable for the bottom and tuyere, and the Sialon reinforced corundum-silicon carbide-mullite injection material are prepared. The correlation between the microstructure and properties of each castable is studied, and the design principles of the castable and hot injection material for the blast furnace hearth, the bottom, the tuyere and the iron notch are determined. Further research and development of new long-life integrated whole pouring technology for blast furnace and industrialization practice are carried out.

[0037] In the early stage of high use in-situ furnace operation, high titanium ore or titanium dioxide TiO2 is directly added in Al2O3-SiC castable, and the anti-sludge corrosion performance of the castable for furnace bottom and tuyere is further improved by TiC(N) generated in special reducing atmosphere of blast furnace. The relationship between the preparation and sintering process parameters (raw material type, particle size distribution, water addition, sintering temperature, sintering rate, sintering time, etc.) and the product microstructure, pore structure, mechanical properties and thermal conductivity is studied, and the evolution law between the structure and performance of titanium modified Al2O3-SiC refractory castable is revealed. From the aspects of thermodynamic theory simulation and experiment, the slag corrosion process mechanism of titanium modified Al2O3-SiC refractory castable with different components and structures at high temperature is explored, and the best process conditions are obtained.

[0038] Based on orthogonal test design and analysis method, the influence of brown corundum, silicon carbide particle size and ratio, calcium carbonate cement, alumina powder, silicon powder, tripoli, sodium tripolyphosphate, spherical pitch and zirconia addition on the physical and chemical properties (bulk density, porosity and bending strength) of green body of castable is studied. The influence of high temperature sintering temperature and holding time on the microstructure, pore structure, mechanical properties, corrosion resistance and thermal conductivity of the material is studied, and the optimal conditions of ZrO2 composite Al2O3-SiC-C castable for taphole area are obtained.

[0039] Blast furnace hot repair is beneficial to improve the life of the shaft, and realize the matching of the life of the shaft and the hearth. The influence of particle size and addition amount of high alumina bauxite, brown corundum, andalusite, calcium carbonate cement, metallic silicon powder and water reducing agent on the forming properties (setting time, green strength and bulk density) of whisker reinforced Sialon bonded corundum-silicon carbide-mullite castable is studied. The influence of high temperature sintering process (sintering temperature and holding time) on the microstructure, pore structure, mechanical properties and linear expansion coefficient of the material is studied. The influence of raw material ratio and sintering process on the thermal shock resistance of whisker reinforced corundum mullite castable is studied by one-time air cooling method.

[0040] The expansion coefficient of each castable is calculated, and the expansion joint is reserved. The above prepared micro-nano bonded Al2O3-SiC castable, titanium modified Al2O3-SiC refractory castable, Sialon reinforced corundum-silicon carbide-mullite castable and other supporting materials prepared by the enterprise are integrated and fully poured in the blast furnace, and then the curing, demolding, baking and other processes are carried out.

[0041] In the preparation process of the functional element of the blast furnace lining, the formation of various phases such as Al2O3, SiC, Si3N4 and mullite will be accompanied by changes in microstructure and pore structure; the introduction mode of aluminum source, silicon source and carbon source will affect the pore and microstructure of the final product during high-temperature pyrolysis; in addition, the pouring process, the introduction of the binder and the heat treatment system will also affect the pore and microstructure parameters of the functional element, so it is feasible to realize the regulation of the pore and microstructure parameters of the functional element by process parameter regulation.

[0042] The refractory used for integrated full-furnace pouring is all unshaped refractory, which can realize integrated full-furnace pouring of the blast furnace lining, replace the traditional blast furnace lining formed by masonry of shaped refractory, and the refractory configuration for full-furnace pouring is directly carried out full-furnace formwork pouring and pouring in close contact with the carbon brick, carbon ring, iron notch and cooling wall in the furnace, and then the maintenance, form removal and furnace baking processes are carried out, once forming, and the full-furnace pouring only needs baking and does not need high-temperature sintering process, which has the advantages of simple process and energy saving and environmental protection.

[0043] The beneficial effects of the present application are:

[0044] The present application obtains the temperature field distribution physical model, mathematical model and boundary conditions of the blast furnace bottom and hearth through finite element analysis of the key part of the blast furnace, i.e. the hearth structure, simulates the temperature field and pressure field distribution of the blast furnace body, firstly simulates the temperature field distribution in the blast furnace, optimizes the overall structure of the hearth according to the failure mechanism of the refractory in different areas, and obtains the best pouring material selection through digital simulation according to the structural characteristics, which can greatly shorten the construction time of the blast furnace, and the refractory used for integrated full-furnace pouring is all unshaped refractory, which can realize integrated full-furnace pouring of the blast furnace lining, replace the traditional blast furnace lining formed by masonry of shaped refractory, and the refractory configuration for full-furnace pouring is directly carried out full-furnace formwork pouring and pouring in close contact with the carbon brick, carbon ring, iron notch and cooling wall in the furnace, and then the maintenance, form removal and furnace baking processes are carried out, once forming, and the full-furnace pouring only needs baking and does not need high-temperature sintering process, which has the advantages of simple process and energy saving and environmental protection, the structure is more unified, and the service life of the blast furnace can be greatly enhanced.

[0045] Although the embodiments of the present application have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations can be made to the embodiments without departing from the principles and spirit of the present application, and the scope of the present application is defined by the appended claims and their equivalents.

Claims

1. A novel in-situ corundum-silicon carbide material system and lining process for integrated blast furnace lining, characterized in that, This includes the physical model and mathematical model of the temperature field distribution in the hearth and furnace hearth obtained through finite element analysis simulation of the temperature and pressure field distributions in the blast furnace body, as well as the boundary conditions Γ1 to Γ6. The conditions for each boundary from Γ1 to Γ6 are as follows: The Γ1 boundary is the centerline boundary of the furnace hearth. There is no heat transfer at this boundary, so it is considered an adiabatic boundary. The Γ2 boundary is adjacent to the furnace bottom cooling system and is the outer boundary of the entire system, which is considered as a convective boundary. The Γ3 boundary is close to the furnace hearth cooling system and is the outer boundary of the entire system, which is considered as a convective boundary. Since the heat flow inside the furnace mainly flows along the r direction, the Γ4 boundary is considered an adiabatic boundary. The Γ5 boundary is the erosion boundary where molten iron contacts the furnace lining refractory material. The temperature field of this boundary and its surrounding area is simulated and calculated. The Γ6 boundary is the upper surface of the molten iron. Since the hot molten iron continuously drips from the softened layer to the hearth during the operation of the blast furnace, providing heat for the system, this boundary is regarded as the isothermal boundary.

2. The integrated in-situ lining corundum-silicon carbide new material system and lining process for blast furnaces according to claim 1, characterized in that, One to three typical blast furnaces were selected for geometric modeling, and ten regions were divided according to different lining materials. The temperature field changes were analyzed by changing the thermal performance parameters of the materials in each region. The Fluent solver of ANSYS software was used to perform iterative simulation calculations on the material properties of different refractory linings required in each region of the model. The Result module was used to post-process the calculation results and output the temperature field distribution map.

3. The integrated in-situ lining corundum-silicon carbide new material system and lining process for blast furnaces according to claim 1, characterized in that, Based on the Al2O3-SiC phase diagram and orthogonal experimental design and optimization analysis, this study investigates the effects of particle size and proportion of dense corundum and silicon carbide, nanocomposite binder, calcium carbonate cement, Guangxi white clay, alumina micro powder, silica micro powder, sodium tripolyphosphate, and nano silica sol on the physicochemical properties (bulk density, porosity, and flexural strength) of the castable green body. The study also examines the effects of high-temperature firing temperature and holding time on the material's microstructure, pore structure, mechanical properties, erosion resistance, and thermal conductivity, ultimately obtaining optimized preparation conditions for micro / nano-bonded Al2O3-SiC castables for furnace hearths.

4. The integrated in-situ corundum-silicon carbide lining new material system and lining process for blast furnaces according to claim 1, characterized in that, In the early stage of operation of the blast furnace, high-titanium ore is added or titanium dioxide (TiO2) is directly added to Al2O3-SiC castable. The TiC(N) generated by the special reducing atmosphere of the blast furnace further improves the slag erosion resistance of the castable at the furnace bottom and tuyeres.

5. The integrated in-situ lining corundum-silicon carbide new material system and lining process for blast furnaces according to claim 1, characterized in that, Based on orthogonal experimental design and analysis, this study investigated the effects of brown fused alumina, silicon carbide particle size and proportion, calcium carbonate cement, alumina micro powder, silica micro powder, fused alumina, sodium tripolyphosphate, spherical asphalt, and zirconium oxide addition on the physicochemical properties (bulk density, porosity, and flexural strength) of the castable green body. The study also investigated the effects of high-temperature firing temperature and holding time on the material's microstructure, pore structure, mechanical properties, erosion resistance, and thermal conductivity, obtaining the optimal conditions for ZrO2 composite Al2O3-SiC-C castables used in the iron taphole region.

6. The integrated in-situ lining corundum-silicon carbide new material system and lining process for blast furnaces according to claim 1, characterized in that, Calculate the expansion coefficient of each castable and reserve expansion joints; then cast the micro-nano bonded Al2O3-SiC castable, titanium modified Al2O3-SiC refractory castable, seron-reinforced corundum-silicon carbide-mullite sprayed material and other supporting materials made by the enterprise into an integrated blast furnace, and then carry out curing, demolding, and furnace drying processes.

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