Application problems and waterproof treatment of magnesia calcium refractory brick

At present, the problems in the production and use of magnesia calcium refractory bricks are as follows:

(1) Research on waterproof technology.

Hydration is still the core problem affecting the application of magnesia calcium refractory brick. If the hydration problem is not solved, it cannot be applied. The hydration mentioned here includes production, storage, transportation and use. At present, there is no synthetic magnesia calcium sand with complete hydration resistance. Magnesia calcium sand and its products cannot be stored and transported for a long time, and there are more or less damage problems caused by hydration. Although a variety of anti hydration measures have been adopted after years of research, this problem has not been completely solved. Hydration resistance is also a major research topic.

Application problems and waterproof treatment of magnesia calcium refractory brick

(2) Industrial production of water resistant magnesia calcium sand.

Although the synthetic magnesia calcium sand produced in China at present also adopts the two-step calcination process, it is calcined in the billet tunnel kiln or the ball pressing shaft kiln. The fatal weakness is that after crushing, almost all the particles form a new surface, multi edges and corners, and the hydration resistance is poor, which causes great difficulties in storage, transportation, production and use, so it is difficult to popularize and apply. Rotary kiln production is ideal, but the cost is high, and it is difficult to promote ◦ good water-resistant magnesia calcium sand. There are few manufacturers and limited production capacity, which can not meet the needs. Whether a large number of synthetic magnesia calcium sand with excellent hydration resistance can be produced in industry will play an important role in the popularization and application of this kind of materials.

(3) Production of high efficiency binder.

In the production of general magnesium calcium products, paraffin is used as the binder, and the surface of the products is also soaked with wax and oil, which often causes pollution and harm to the environment in the process of production and use. For the binder used in the production of magnesia calcium refractory products, it is required to play the role of binder in brick making and can not bring water. In addition, it can also play the role of waterproof in the storage process, especially can not pollute the environment. At present, it is urgent to develop good, low-cost and pollution-free binders.

(4) Basic research.

At present, there is a lack of in-depth research on the waterproof technology of good synthetic magnesia calcium refractory bricks, and there is a lack of systematic research on the interaction mechanism between magnesia calcium refractory bricks with different CaO content and molten steel.

Waterproof technology of magnesia calcium refractory brick

Although magnesia calcium refractory brick has a series of excellent properties, its easy hydration parts limit the application of this material. In order to vigorously develop magnesia calcium refractory brick, the hydration problem must be solved. At present, the waterproof methods of magnesia calcium refractory brick at home and abroad generally include:

(1) Surface treatment.

1) Magnesium calcium sand is treated with phosphoric acid to form phosphate compound on the sand surface, cover the surface, isolate the air and play the role of waterproof.

2) Wet the surface of magnesia calcium sand with a certain concentration of silicone solution, and then dry it to form a covering layer on the sand surface, which plays a waterproof role.

3) CO2 and water vapor are passed through the surface of magnesia calcium sand and magnesia calcium brick to form a carbonate compound covering layer, which plays a waterproof role.

4) Spray a layer of anhydrous organic matter, dehydrated asphalt, anhydrous resin and other protective films on the surface of magnesium calcium brick to prevent the brick surface from contacting with the atmosphere and play the role of waterproof.

(2) Additives.

When manufacturing magnesia calcium sand, add a small amount of additives, such as Bao, SrO, Al2O3, B2O3, yao3, SiO2, TiO2, ZrO2, CaF2, rare earth oxides and composites. These additives interact with Cao to form low melting point substances or solid solutions, improve microstructure, promote sintering and play a waterproof role.

(3) Sintering method.

High temperature sintering or two-step calcination can make Cao grains grow, fully sintered, densified, reduce grain boundary area and play the role of waterproof.

(4) Sealed packaging.

The products shall be packaged by hand, thermoplastic, vacuumized, etc., and the surface of the products shall not be in contact with the atmosphere as far as possible, so as to play a waterproof role.

(5) Production process control.

Check all links of the material production process to minimize the hydration of magnesia calcium sand or brick blank, such as selecting high-density raw materials, brick preheating, anhydrous binder, reasonable particle grading, light burning, oil immersion, wax immersion, etc.

The above waterproof methods can reduce the hydration problem of magnesia calcium refractories to varying degrees. At present, additive method, vacuum packaging or wax dipping treatment are widely used. In terms of waterproof effectiveness, comprehensive methods are generally adopted, and hydration should be considered from raw materials to finished products.