Application status of waste refractory materials in the steel industry
Refractory material are widely used in the iron and steel industry. Metallurgical industry or building material production enterprises need to purchase a large number of refractory materials required for high-temperature operations to ensure continuous production. In the production process of iron and steel enterprises, a large amount of waste refractory materials will be produced, such as the daily repairs of furnaces and kilns in iron and steel smelting and the middle repairs and overhauls of molten iron tanks and ladles.
Generally speaking, most steel companies will use landfill to treat these waste refractory waste materials. With the transformation and upgrading of the steel industry and the construction requirements of energy conservation and environmental protection, waste refractory materials in the steel industry have been selected, classified and special Process treatment can re-form high-value refractory raw materials for comprehensive development and recycling, which not only helps promote the transformation and upgrading of the steel industry, realizes the economic cycle of steel enterprises, but also saves materials and energy, and reduces the economic loss of enterprises.
At present, the total annual output of refractory waste in China is rising. These waste refractory materials not only cause a lot of waste of resources, increase the production and processing costs of steel companies, but also cause pollution to the environment. With the increasing pressure on the cost of iron and steel, the recycling of waste refractory materials has attracted the attention of iron and steel enterprises. By processing the discarded refractory materials in the technological process, new products with industrial value can be obtained.
Application processing of waste refractory materials
As a large-scale steel group with an annual output of 10 million tons in the northwest region, Shaanxi Iron and Steel Group is committed to building a first-class steel material supplier in the western region. The annual consumption of refractory materials is huge. In addition to the partial contracting of ton product costs, the group also has Refractory production, and processing enterprises will screen, recycle, and reuse some waste refractory materials. At present, the process of recycling waste refractory materials is shown in Figure 1.
The first step is to carry out material classification and screening of waste refractory materials. In the recycling of a large number of waste refractory materials, these waste refractory materials generally flow from three aspects:
- First, some waste refractory materials are directly treated as waste garbage;
- The second is to remove impurities adhered or deteriorated parts of waste refractory materials through cleaning, hydration treatment, etc., and directly use the partially removed refractory materials;
- Third, after cleaning and chemical treatment of the waste refractory materials, another part of the waste can be selected and classified for production recovery. The preliminary product raw materials can be obtained through the processing process of residual bricks and refractory castable residue lining, and then the raw materials are used as Use granular materials for processing.
Although the application methods of these waste refractory materials can solve some environmental problems and achieve some economic benefits, they also greatly reduce the quality of the products. Therefore, in the application and processing of waste refractory materials, a further application method is to waste refractory materials. Carry out comprehensive processing and utilization of process technology reproduction, such as adding new refractory production raw materials, synthesizing new materials using refractory production technology, or purifying substances, or disposing of waste refractory materials by micro powder or nano Powder processing enables it to be used more fully as a flux in other processes such as sintering. In the application process of waste refractory materials, the iron and steel industry should strive to develop new ways of using waste refractory materials to enhance the application value of waste refractory materials, so as to achieve the goal of improving the utilization rate of waste refractory materials and zero-waste materials.
Exploration of the application of waste refractory materials in the steel industry
1. Waste refractory materials should be strengthened for classification and recycling
In the steel industry, there are many types of waste refractory materials and complex compositions. In order to maximize the reasonable use of different waste refractory materials, it is necessary to carry out classification research according to the chemical properties, production methods, and supply forms of waste refractory materials. Iron and steel enterprises sort and sort various waste refractory materials through the unified recycling of waste high-alumina bricks, magnesium bricks for furnace wall construction, skateboards for hot metal cans, waste castables of ferroalloy smelting furnaces, ladle castables, etc. According to magnesium oxide series, alumina series, carbon-containing series, carbon-free series, etc., the mixed heterogeneous materials or iron pieces must be separated by magnetic separation and other methods. It can be roughly formed into different materials such as waste magnesium carbon brick, waste aluminum-magnesium carbon brick, waste aluminum-silicon carbide brick, waste magnesium brick, magnesia chrome brick, waste high aluminum brick (including mullite and corundum brick), these products It can be directly used for the production material needs of individual steel companies.
2. New refractory materials should be added in proportion
After sieving waste refractory materials in the iron and steel industry, they can be mixed with new refractory materials for in-depth recycling and processing, and then processed into new refractory products through extrusion molding, melt casting molding or casting molding and other production methods. To meet the different needs of using refractory materials in other processes, and reduce the cost of refractory preparation in the production and operation of iron and steel enterprises. At present, a considerable amount of exploration has been carried out on the method of compounding materials, and some achievements have been made in the regeneration of dense refractory aggregates and the separation of recycled aggregates using chemical reagents, making many types of Waste refractory materials can be fully recycled by blending new materials. However, in the future development process, it is also necessary to further promote the comprehensive application of waste refractory materials, improve the added value and process level of recycled products, so that the application range of waste refractory materials is more extensive, reducing the environmental impact of refractory solid waste on the environment Pollution.
3. Improve the recycling technology of waste refractory
A lot of practice shows that improving the technical process and application level of waste refractory materials can, on the one hand, improve the erosion resistance and wear resistance of waste refractory products, effectively improve the quality of waste refractory reproduction, and reduce the loss of refractory materials. To optimize the role of waste refractory recycling; on the other hand, it can also be widely used in blast furnace ironmaking, hot metal pretreatment, furnace refining, and converter steelmaking, which not only reduces production risks but also effectively Increased the output and quality of iron and steel metallurgy. Therefore, to strengthen the application of waste refractory materials in the steel industry, not only the comprehensive utilization of various types of refractory materials but also the regeneration technology of waste refractory materials and the technical process of the residual lining of different types of refractory castables Processing applications. Comprehensive recycling technologies such as CTG-2A main trench joint ramming material, steel-making splash-proof aluminum carbon brick, and CAS dip tube middle can effectively improve the performance of high-value-added products of different waste refractory materials and make waste refractory materials comprehensive. Recycling can fully meet the technical requirements of the steel industry.
4. Difficulties in the treatment of waste refractory
Current problems: (1) The crushing, screening, and magnetic separation equipment for recycling waste refractory materials are not yet mature and is limited to the crushing, screening, and recycling of some refractory materials. ) High labor cost for recycling. The high hardness of the refractory itself, combined with the high-temperature erosion during the production process, forms complex organic and inorganic compounds. Crushing and screening are laborious and low in production efficiency. At the same time, because of the special requirements for the material, it must be kept dry. Dust will appear, and a large amount of dust and other equipment and facilities will need to be invested in personnel and the environment, resulting in increased environmental protection costs. (3) The production rhythm of the iron and steel industry is tight and recovery is difficult. The dismantling and recycling of waste refractory materials can only be carried out in the production and maintenance gap. At the same time, the damaged equipment must be repaired in time. The impact of recycling.
In summary, as a renewable resource, waste refractory materials can effectively reduce the production costs of the steel industry, promote environmental protection and the sustainable development of steel companies, and thus improve the economic and social benefits of the production and operation of the steel industry. At present, the application of waste refractory materials in the iron and steel industry has reached a certain scale, such as scrap iron trench materials and waste magnesia carbon bricks have gradually been comprehensively recycled. At the same time, in the future development of the iron and steel industry, the application and recycling of waste refractory material should be maximized, and the high value-added steel products produced from waste refractory materials should be continuously improved to further develop other applications of waste refractory material. the way.