The recycling and reuse of refractory materials has attracted more and more attention. If refractory materials can be fully and effectively utilized, it will not only reduce the mining of refractory minerals, reduce the cost and energy consumption in the production and preparation process of refractory raw materials, but also save money. The transportation cost of refractory raw materials is conducive to resource conservation, energy saving and environmental protection.
1. Overview of foreign countries where refractory materials can be recycled Overseas developed countries attach great importance to the reuse of post-consumer refractory materials. They understand it from the perspective of resources and environmental protection, and have even formulated laws and regulations to strictly limit the emissions of post-consumer refractory materials, which has greatly promoted the research on the reuse of post-consumer refractory materials. , the recycling rate of refractory materials after use has reached more than 60%, and is constantly improving.
A Japanese steel mill uses waste bricks as the main raw material to develop ramming materials around the bottom of the ladle, ladle castables and shaped products. For example, 85% recycled materials and 15% new materials are used to produce unburned electric furnace melting pool parts. Magnesia bricks, using 90% recycled materials and 10% new materials to produce magnesia carbon bricks for electric furnace slag lines, and using all recycled materials to produce RH bottom fired magnesia chrome bricks, etc. Kurosaki Company used waste corundum graphite products as raw materials to develop immersed nozzle bricks. Kashima Steel Company has developed a secondary utilization process for skateboard tiles. It uses surface grinding, castable casting restoration method, and ring inlay method to make the repaired skateboard achieve the same use effect as a new skateboard; the waste refractory materials of the tap hole are used Reused, mainly used as aggregate for A12O3-SiC-C castables.
The Italian company OfficineMeccanichediPon-zanoVenetto has developed a technology for recycling post-consumer refractory materials, which is mainly used to recycle refractory materials lining various kilns, tundishes, ingot molds and ladles, and inject the recycled refractory materials directly into the furnace. , to protect the furnace wall. In the past, the United States only recycled a small amount of waste refractory materials, and almost all the rest were buried. In 1998, the U.S. Department of Energy, the Department of Industrial Technology and steel producers jointly formulated a three-year plan to extend the service life of refractory materials and recycle waste refractory materials. Government support, cooperation with enterprises and research institutions have strengthened the research on post-consumer refractory materials. The applicable scope mainly includes: desulfurizer, slag modifier (slagging agent), slag splashing furnace protection additive, calcium aluminate cement Raw materials, refractory concrete aggregates, paving materials, ceramic raw materials, glass industry raw materials, granular materials for roof construction, abrasives, soil modifiers. The cooperation between refractory factories and users has minimized the amount of discarded refractory materials. The United States has also conducted research on the use of post-dolomite bricks as soil conditioners and slag-forming agents, and achieved good results.
The earliest research work on waste refractory materials in India can be traced back to 1978. It was first carried out in the Steel Pipe Company, using waste high alumina bricks (60%~) generated from the heating furnace of the Indian Steel Pipe Company (now TISCO Steel Pipe Branch) 62% alumina) to produce castables (56% alumina), fire clay (50% alumina) and refractory plastics. The developed casting materials are mainly used to produce burner bricks, dampers, tiles, etc., and can meet the internal requirements of the industry.
2. Domestic overview of recycling and utilization of refractory materials my country’s research on the reuse of post-consumer refractory materials started late, and the reuse rate is relatively low. According to relevant reports, the recycling rate of post-consumer refractory materials in my country is about 20%. Even the reused part comes at the expense of reduced product quality. In recent years, major domestic steel mills and most refractory material factories have attached great importance to the recycling and reuse of used refractory materials, and have continued to carry out research and application work in various aspects.
Baosteel’s reuse of used refractory materials is going well. The blast furnace main trench castables have all been recycled and used as raw materials for slag trench castables. The recycled magnesia carbon bricks prepared after regenerating the used magnesia carbon bricks have anti-oxidation and It has the advantages of strong slag resistance and long service life. After WISCO classifies the used aluminum-magnesia carbon residual bricks and removes impurities, it manually removes the sticky slag layer and transition layer, conducts magnetic separation and hydration treatment, uses a jaw crusher to crush the materials to less than 25mm, and finally uses Hammer crusher processes it into the required particle size to prepare recycled alumina-magnesia carbon bricks.
Jinan Iron and Steel Co., Ltd. uses aluminum carbon refractory materials (discarded skateboard bricks, seat bricks, nozzles, plug rods after use) as iron trench ramming materials to replace some of the high-aluminum materials. Use the used magnesia chrome brick as raw material and add it to the RH gunning material in a certain proportion, and the effect will be good. At the same time, the prepared recycled magnesia-chromium bricks have better performance and have better application prospects in non-critical parts of cement kilns and RH. At present, domestic scientific researchers have also proposed: by adding an appropriate amount of beneficial oxides to the used refractory materials to improve and optimize the high-temperature performance, and prepare high-quality modified materials; prepare transformed materials through high-temperature reduction reactions, such as SiC, -Sialon , Mgalon, etc.; use post-consumer clay bricks and post-consumer skateboard bricks to synthesize mullite; use post-consumer silica bricks and use C as the reducing agent to synthesize SiC; use post-consumer skateboard bricks to synthesize -Sialon; use post-consumer skateboard bricks, post-consumer Magnesia carbon bricks are synthesized with oxide and non-oxide composite materials such as Mgalon, so that the products have excellent properties such as high strength, thermal shock resistance and corrosion resistance. As new high-efficiency refractory materials, they are used in key parts of high-temperature equipment, thereby realizing resource and efficient use of energy. The recyclability of refractory materials has become the current development trend of the refractory materials industry. If you want to make a breakthrough in the refractory materials industry, you must develop in line with the needs of society.
