According to the reasons for the damage of the blast furnace brick lining and the requirements of the working conditions of the blast furnace, it is proposed that the slag corrosion resistance, alkali resistance and micro-porosity index reach an excellent level as the research goal.
The microporous corundum brick is made of fused dense corundum as raw material, with a small amount of additives, using a unique micro-porous production process, using phenolic resin as a binder, molded and molded at high temperature, and then processed by machine tools and pre-assembled. Ensure the brick joint requirements of the masonry.
For ceramic refractories, solving the slag corrosion resistance, alkali resistance and production of micro-porous bricks are three major technical problems. Because ceramic refractories are generally easily corroded by slag and have poor alkali resistance. The alkali resistance and slag erosion resistance of corundum material is very good. It is feasible to use corundum as the raw material. The key is what binder is used to make the base material of the brick have the same slag resistance and alkali resistance as corundum. Therefore, the binding agent is the focus of research.
After testing a variety of binders, it is found that when phenolic resin is used as the binder, it has a significant effect on improving slag resistance and alkali resistance, and can produce corundum bricks with excellent alkali resistance, slag resistance and iron corrosion. Phenolic resin is a combination of carbonaceous materials and has low strength. Obviously, high-strength microporous corundum bricks cannot be produced completely with this binder.
In order to produce micro-porous bricks, a variety of additive tests were carried out to find out the mechanism of micro-porous formation. Three conditions must be met for the production of micro-porous bricks:
(1) The structure of the bricks is relatively dense, with small and few pores; (2) The added additives can be melted and gasified at high temperatures to redistribute into smaller pores, fill the pores, and generate new substances with stable properties: (3) The firing temperature can meet the requirements of micro-pore formation.
Studies have shown that the type, amount, and method of additives have a great influence on the performance of bricks, especially the properties of alkali resistance, slag erosion resistance, compressive strength, average pore size, pore volume <1μm, and air permeability. It is necessary to strictly control its dosage and particle size in order to achieve the desired effect. The micro-pore index of the micro-pore brick inspection is the average pore diameter, the pore volume of <1μm and the air permeability. These three indexes can fully reflect the pros and cons of a certain brick micro-pore index. Excellent micro-porous bricks can effectively prevent the penetration and erosion of harmful substances in molten iron, K, Na, Zn, and Pb.
The blast furnace ceramic cup hearth bottom structure is a new type of hearth bottom structure developed after the integration of the bottom and water-cooled carbon brick thin furnace structure, which has obvious advantages.
(1) The microporous corundum brick has good resistance to slag and iron corrosion and alkali resistance. It is a microporous brick production process. It has excellent air permeability, average pore size, and pore volume <1μm. Its product performance and quality level are fully up to date. It has reached the world's advanced level and is currently the best brick for blast furnace ceramic cups.
(2) Microporous corundum bricks were successively used as ceramic cup wall tiles in No. 6, No. 4, No. 7, No. 5, and No. 8 blast furnaces of Wuhan Iron and Steel Co., Ltd., and the effect was very good. The No. 6 blast furnace was opened in July 2004, 2014 On October 6th, the blast furnace was renovated and overhauled. The tuyere cooling stave and composite bricks were replaced. Observations in the furnace revealed that the uppermost layer of microporous corundum bricks still existed.
(3) The air permeability of brown corundum bricks and corundum mullite bricks is very high. K, Na, Zn, deposited carbon, etc. are easy to penetrate into the bricks, and it is easy to corrode the bricks from the inside, especially due to the continuous invasion of alkali metals. The volume expansion of the ground causes the tuyere to be upturned. The microporous corundum brick has excellent alkali resistance and excellent microporous brick index, which is very suitable for the application of blast furnace tuyere belt. The microporous corundum brick has been used in the overhaul of No. 5 and No. 8 blast furnaces of Wuhan Iron and Steel. The second generation of No. 5 blast furnace has been used for more than 6 years, and the current use effect is very good, and there is no upturning of the tuyere.
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