For blast furnaces with only a single taphole, the tapping interval is short and the wind-off time is short. If low-cement castables are used, sufficient baking time cannot be guaranteed, so most of these blast furnaces still use unbaked iron ditch ramming materials.
Unbaked ramming materials have the disadvantages of loose structure, poor oxidation resistance, low iron flow, and high labor intensity of on-site construction; there are also those that use iron ditch prefabricated parts for splicing and installation, but there has been no good solution to the joint treatment problem, so how to effectively solve the life of the iron ditch of a single taphole blast furnace has attracted much attention. To this end, our R&D personnel have developed unbaked castables suitable for blast furnace iron ditch after a lot of analysis and research on the working conditions, damage mechanism, chemical composition of molten iron and slag of the blast furnace iron ditch.
When the water content of ordinary low-cement castables is high, the water will be discharged in large quantities and quickly when the temperature rises sharply. When the water discharge channel is not smooth, the water cannot be discharged in time, and the steam pressure surges, which will cause the material to burst. This material has the following problems: ① Since alumina cement is used as a hardener, the introduction of Ca0 causes a low melting point of the matrix, which reduces corrosion resistance; ② Adding a drying aid metal Al powder, the addition of metal Al powder is effective for drying, but the construction body is prone to cracking, which leads to a tendency of tissue deterioration; ③ Phosphate-bound materials have a binder migration problem, which causes ion enrichment on the surface of the material, blocks the pore channels, and is prone to layering, bursting and peeling.
The design idea of the baking-free refractory castable is to use the characteristics of the castable's dense structure and convenient construction, and use non-aqueous liquid organic compounds as fluidity imparting agents and binders to ensure the construction fluidity of the castable. Alkaline materials are used as hardeners and added to the mixed refractory bulk materials for stirring to obtain a material with fluidity that can be vibrated for construction. After casting and molding, it is hardened and demolded in a very short time at room temperature or under the residual heat of the trench body. Since the moisture content in the material is very low, it does not need to be baked and can be directly tapped, achieving the purpose of reducing operation time, reducing labor intensity, and increasing service life.
The materials for the iron ditch must have high performance such as corrosion resistance and wear resistance. The materials used in our products are made of high-grade raw materials with strictly managed particle size as aggregates, and a mixture of clay and various bonding materials that can produce hot strength in various temperature ranges, fused brown corundum (good corrosion resistance, wear resistance, strong resistance to molten iron.
In order to improve the service life of the ditch material, the porosity of corundum must be low), carbon and silicon carbide (small volume change with heat resistance, difficult to be wetted by molten iron and slag, chemical stability, carbon can adapt to iron and slag, and silicon carbide is more suitable for slag), bonding materials (non-aqueous liquid organic compounds, bonding materials that can maintain strong organizational strength from low temperature to high temperature, ensuring sufficient strength of the material), and antioxidants, dispersants and other additives are added to improve material properties.
High-strength corundum refractory castable products
Including corundum castables, corundum plastics, corundum ramming materials, corundum wear-resistant materials. Corundum products are made of refractory products with Al2O3 content greater than 90%, corundum as the main crystal phase, and are compounded with appropriate amounts of dispersants, coagulants, stainless steel fibers, and are made according to strict formulas. They have many characteristics such as good high-temperature strength, wear resistance and erosion resistance, high thermal conductivity, thermal shock resistance, corrosion resistance, good sealing, rapid setting and early strength. The products are widely used in circulating fluidized bed boilers, metallurgy, petrochemicals, thermal power and other industries.
(1) Adding a certain proportion of steel fibers and additives to the castable can produce steel fiber castables with good thermal stability and strong wear resistance, which are used in heating furnace beds, steel spouts and cement rotary kiln mouths.
(2) According to user requirements, this series of castables can be used to process various refractory prefabricated parts according to drawings.
Corundum castables Corundum refractory castables are made of fused corundum as the main raw material, combined with a variety of super-fine and high-efficiency additives.
The main features are high strength, good volume stability, excellent corrosion resistance, and no influence from reducing gases such as H2 and CO.
A refractory castable made of corundum as aggregate and powder and some binders. It has higher mechanical strength and abrasion resistance than high-aluminum refractory castables and mullite refractory castables, but its thermal shock resistance is slightly worse. It is mainly used as lining materials for various kilns such as boilers, blast furnace hot blast furnaces, heating furnaces, ceramic kilns, etc.
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