There is a long way to reuse refractory materials after use in China

Mineral resources in Dashiqiao are very important to everything, especially many non-renewable resources. More and more attention has been paid to the recovery and re-use of fire-resistant materials after use, and the research work has been carried out in depth. Because after the use of refractory materials scattered throughout the country, if it can be fully and effectively used, not only to reduce the amount of refractory mineral mining, reduce refractory production, preparation process costs and energy consumption, but also to save the transportation cost of refractory materials, is conducive to resource conservation, energy saving and environmental protection, with significant economic and social benefits.

Foreign countries pay attention to the use of fire-resistant materials after use

Some especially developed very much pay attention to the re-use of fire-resistant materials after use, from the height of resources, environmental protection to know, and even the formulation of laws and regulations to severely limit the discharge of fire-resistant materials after use, greatly promoted the study of the re-use of fire-resistant materials after use, developed fire-resistant materials re-use rate has reached more than 60%, and is constantly improving.

Some steel mills in Japan use waste brick as the main material, and announced the ramming material around the bottom of the ladle, the ladle castable and the styling product. For example, 85% recycled material and 15% new material are used to produce non-fired magnesia bricks for the melting pool of the electric furnace, 90% recycled material and 10% new material are used to produce magnesia carbon bricks for the electric furnace slag line, and all are used to produce RH bottom fired magnesia chrome bricks. Using waste corundum graphite products as material, Kurozaki company announced the introduction of immersed water mouth brick. Kashima Steel Company announced the secondary use of skateboard bricks, the selection of surface grinding, castable casting restoration method, ring Mosaic method, so that the repaired skateboard to achieve the same use of the new skateboard; The waste refractory material of iron ditch is used repeatedly, mainly as aggregate of A12O3-SiC-C castable. Zhiduo Plant of Datong Special Steel Co., Ltd. has developed the recycling technology of waste brick in order to solve the problem of increasing the floor area of many disposable firebricks. For example, the plant classifies the waste bricks, adjusts the composition and particle size after crushing processing, selects the ladle waste brick containing MgO-C, Al2O3-MgO-C instead of light burned dolomite brick as the slag making agent of LF furnace (ladle furnace), through the industrial test, the refining function in the slag formation and the removal speed, and the liquid steel is not happy during the operation, and achieves the expected test effect; Choosing AOD furnace dolomite waste brick instead of CaO as slag making agent in EAF stainless steel smelting not only achieves the original smelting effect, but also plays a role in inhibiting MgO melting loss in refractory brick. Mgo-c and MgO waste bricks were selected as the primary raw materials to prepare recycled refractory bricks, and MgO amorphous refractory materials and Al2O3 ramming materials were prepared with waste bricks as the primary raw materials, and were successfully applied to the parts of ladle with low heat load and non-severe erosion parts. Nippon Steel intends to break and screen the powder and recycle it into oxidizing slag by melting powder furnace, so as to realize the recycling of the refractory material after use.

Valoref, founded in France in 1987, specializes in the global disposable refractory material business, dealing with after-resistant materials for glass kilns originating in France and abroad. The recovery rate of refractory materials for French die-casting glass kilns was 24% in 1993, and reached 60% in 1997. Valoref has invented a number of recovery and reuse processes, using materials from the glass industry, steel industry, chemical industry, incineration industry discard refractory materials, the company also announced a better recovery use of unfurnace method.

Italy Officine Meccaniche di Pon-zano Venetto announced a recovery after fire data technology, mainly used to recover a variety of kiln, center ladle, ingot mold and ladle lining fire data, and the recovery of fire data directly into the furnace to maintain the furnace wall.

In the United States, only a small amount of discarded fire-resistant materials were recovered, and the rest were almost all buried. In 1998, the United States Department of Power, the Department of Industrial Technology and steel producers jointly formulated a three-year program to extend the service life of refractory materials and recover the use of discarded refractory materials. Government support and the cooperation of enterprises and research institutions have strengthened the research on post-use refractory materials, and the scale of its application mainly includes: desulfurization agent, slag modifier (slag making agent), slag splash furnace protection additives, calcium aluminate cement materials, refractory concrete aggregate, paving materials, ceramic materials, glass industry materials, granular materials for roof construction, abrasive materials, soil modifier. The fire-resistant material factory collaborates with the user to minimize the amount of fire-resistant material discarded. The United States has also studied the use of dolomite brick as soil conditioner and slag making agent, and has achieved outstanding effects.

The earliest research work on refractory abandonment in India can be traced back to 1978, first carried out at the Indian Steel Pipe Corporation (now TISCO Steel Pipe Branch), using the abandonment of high alumina bricks (60%-62% alumina) in the heating furnace of the company to produce castables (56% alumina), fire mud (50% alumina) and refractory plastics. In the meantime, the pouring materials developed are mainly used in the production of burner bricks, dampers, tiles, etc., and can meet the internal requirements of the profession.

The re-use of post-use refractory materials in China is in urgent need of development

The research on the reuse of refractory materials after use started late in our country, and the reuse rate is relatively low. According to relevant reports, the reuse rate of refractory materials after use in China is less than 30%, and the part that is used is also at the cost of reducing product quality. In recent years, the major steel mills and most of the refractory materials factories in China have paid great attention to the recovery and re-use of refractory materials after use, and have continuously carried out discussions and application operations.

The reapplication of refractory materials after use in Baosteel has been carried out well, and all castables in the main ditch of blast furnace have been recovered as castables in the slag ditch. The regenerated magnesia carbon bricks prepared after reprocessing have the advantages of strong anti-oxidation and anti-slag functions and long service life.

Wisco will use the post-aluminum magnesium carbon brick classification, remove impurities, manually eradicate the slime layer and transition layer, and magnetic separation and hydration treatment, with a jaw crusher to break the material to 25mm below, and finally with a hammer crusher processing into the required particle size to prepare recycled aluminum magnesium carbon brick.

Jinan Iron and Steel aluminum carbon refractory materials (after discarding skateboard bricks, seat bricks, water mouth, plug) used in iron groove ramming materials to replace some of the high aluminum materials. The company takes the post-use magnesia-chrome brick as the material, and adds it to the RH spray filler in a certain proportion, and the application effect is outstanding. At the same time, the prepared reclaimed magnesia-chrome brick has good function and good application prospect in the non-critical parts of cement kiln and RH.

The output of steel in the New Heavy Iron and Steel Area reaches 6.5 million tons/year, and the amount of fire-resistant material recovered after use is about 60,000 tons. The primary uses include: Used for the production of recycled magnesia carbon bricks (using the magnesia carbon bricks used in the converter and ladle slag line as the material, through picking, removing external impurities, hydration and other treatment for the regeneration of magnesia carbon bricks), recycled magnesia chromium bricks (adding the post-used magnesia chromium bricks to the RH spray feed in a certain proportion), And the use of ladle lining waste magnesia-aluminum spinel castable from the beginning (the recovered ladle lining waste magnesia-aluminum spinel castable is added to the water glass combined magnesia-aluminum spinel castable in a certain proportion, replacing part of the new castable in the original castable castable, However, it does not affect the application function of the original castable), and the recycling application of aluminum silicon carbide iron trench material (the aluminum silicon carbide carbon recycled material produced by abandoning iron trench material is used for the production of aluminum silicon carbide carbon bricks).

The castable for water jacket lining and central cladding of iron mixing furnace was prepared by using aluminum-magnesium castable for ladle lining. Its application not only satisfied the requirements of the operation function, but also extended the service life of the central cladding 40 times.

Domestic researchers also proposed to improve and optimize the high temperature function by adding an appropriate amount of favorable oxides to the fire resistance after use to prepare high quality modified materials; It is composed of high quality material by secondary calcination of ultrafine grinding. Use the back clay brick and the back slide brick to form mullite; After use silica brick, C as reducing agent to form SiC; β-Sialon is composed of back slide tiles; The composite materials of oxide and non-oxide, such as Mgalon, are composed of post-slide brick and post-magnesia carbon brick, so that the products have excellent functions such as high strength, thermal shock resistance and corrosion resistance, and are used as the key parts of high temperature equipment as a new and efficient refractory material, so as to realize the effective use of resources and power, and so on.