Commonly used refractory materials for garbage melting furnaces include: According to the atmosphere in the furnace, SiC materials and C-SiC materials are often used in reducing atmospheres; Al2O3-Cr2O3 materials and MgO-Cr2O3 materials are often used in oxidizing atmospheres. According to the chemical composition of the slag, the ratio of w (CaO) / w (SiO2) is used as a reference standard. When this ratio is greater than 1, the slag is alkaline and MgO-Cr2O3 materials are often used; when this ratio is close to or less than 1, the slag is acidic and Al2O3-Cr2O3 materials are often used.
Based on the above information, in the discussion of the selection of refractory materials for garbage melting furnaces, the following issues need to be considered:
(1) Constraints on the applicability of materials due to the operating conditions of the melting furnace;
(2) Requirements on the slag resistance of materials due to the chemical composition of the solid pollutants treated by the melting furnace.
Among them, question (1) reflects the rigid requirements of the working environment of the melting furnace for materials, including the applicable temperature, high temperature strength, thermal shock stability and applicable atmosphere of the materials. These requirements can be referenced or screened through existing scientific research results. Question (2) reflects more differences and uncertainties. Different garbage melting furnaces may have different choices of refractory materials even if their working conditions are the same or similar, but they treat different solid pollutants. Therefore, when selecting refractory materials for garbage melting furnaces, the slag resistance of refractory materials should be taken as the key assessment indicator.
Garbage melting furnaces usually have an operating temperature of ≥1300℃, use electric heating process, the atmosphere in the furnace is an oxidizing atmosphere, and the feeding and discharging method is continuous discharging. From the chemical composition of the slag, it can be obtained that the ratio of w (CaO) / w (SiO2) is small and the slag is acidic.
According to the working conditions of the melting furnace, SiC refractory materials can be excluded from consideration, and materials that can be used in an oxidizing atmosphere need to be selected; and because the slag is highly acidic and has a high SiO2 content, MgO-Cr2O3 materials will be greatly corroded by the slag in this environment, so they should also be excluded from consideration. On this basis, for the conditions of strong slag acidity and high SiO2 content, consider selecting materials that are more excellent in resisting glass liquid corrosion as the selected materials, which are: high-purity corundum bricks, chrome corundum bricks and cast AZS bricks. The main chemical composition of the selected materials meets the following conditions: (1) w (Al2O3) ≥ 99.2% in high-purity corundum bricks: (2) w (Al2O3 + Cr2O3) ≥ 99.0%, w (Cr2O3) ≥ 50.0% in chrome corundum bricks: (3) w (ZrO2) ≥ 33.0% in cast AZS bricks.
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