After calcining, dolomite can be made into various dolomite refractory materials. These refractory materials not only have the advantages of high refractoriness and good slag corrosion resistance, etc., the following is the specific application of dolomite in the refractory industry.
Natural dolomite is calcined into dolomite sand, which is then made into dolomite bricks, with CaO content ≥40%, MgO content ≥35%, and a small amount of SiO2, Al2O3, Fe2O3 and other impurities. If the mass ratio of CaO to MgO is less than 1.39, it is called magnesia dolomite brick. Dolomite bricks are mainly used in the burning zone of stainless steel refining furnaces and cement kilns. Only a few cement kilns in my country use imported dolomite bricks.
There are two types: one is a magnesia-calcium brick produced with synthetic magnesia-calcium sand as the main raw material, and the other is a magnesia-calcium brick produced with dolomite sand (or magnesia dolomite sand) and magnesia as the main raw material. Magnesium dolomite bricks. At present, the fired magnesia-calcium brick/magnesia-dolomite brick with a CaO content of 20% is the largest production and consumption of synthetic magnesia-calcium refractory products in China. It is mainly used as a lining material for stainless steel refining furnaces, which is extremely harmful to the environment and human body. The magnesia chrome brick has good effect.
Refractory material that uses sintered dolomite sand, magnesia sand and/or graphite of different particle sizes as the main raw materials and can be used directly without firing. It has energy saving, good thermal shock stability, simple production process, and good slag resistance. . At present, the CaO content of unburned magnesia-calcium (carbon) bricks produced in my country is between 10% and 30%. They are magnesia-calcium products with medium and low calcium. They are mainly used for the bottom of the refining furnace and the molten pool, and the bottom of the GOR furnace. good. However, due to the high price and the need to improve the performance, it has not been widely promoted and applied.
Dolomite is also used to prepare a variety of magnesium-calcium amorphous refractories such as electric furnace bottom ramming material, tundish coating material, ladle gunning material, converter gunning material, RH furnace gunning material, artesian heating material, etc. Among them, the most used is the magnesium-calcium-iron dry ramming material for the bottom of the electric furnace. my country encourages the development of electric furnace steelmaking, the number of UHP electric furnaces continues to increase, and the demand for various dry bottom ramming materials will also continue to increase. In addition, the gunning material developed by dolomite is used for the repair of converters, electric furnaces, ladle slag lines, RH insertion pipes and other parts, with good effects; it can also produce tundish coating materials and dry materials with excellent performance.
In order to expand the application of dolomite resources in refractory materials, research has been done on the use of natural dolomite ore to synthesize calcium aluminate cement containing magnesia alumina spinel. It is a new type of binder for refractory materials. Its CaO content is reduced and it contains magnesium-aluminum spinel. Compared with ordinary aluminate cement, it has better high-temperature volume stability, thermal shock resistance and slag erosion resistance. performance. There are also researchers using natural dolomite ore and different aluminum sources to synthesize calcium aluminate-magnesia alumina spinel lightweight refractory materials, and calcium dialuminate-magnesia alumina spinel composite materials that are resistant to cement clinker erosion. Good progress.
Dolomite refractories have good chemical stability to slag and metals, and the demand will continue to increase. The dolomite high-efficiency mills we produce can be used for dolomite sand powder processing, and are high-performance and environmentally-friendly equipment options.