We know that silicon steel has the characteristics of high permeability, low coercivity and large resistivity. After the oriented silicon steel is decarburized in a continuous furnace, the upper and lower surfaces of the strip are evenly coated with magnesium oxide coating solution. Magnesium oxide mainly acts as a spacer to prevent the strip from sticking at the high temperature annealing stage, and can remove impurities such as nitrogen and sulfur in the steel, in addition to reacting with silicon dioxide on the surface of electrical steel to form an excellent magnesium silicate insulating base. Therefore, the coating quality of magnesium oxide coating liquid on the surface of oriented silicon steel plays a crucial role in the quality of electrical steel products.

electrical steel magnesium oxide is a small particle size, good suspension in water, low hydration rate, with a certain particle size distribution range of white powder, is a special magnesium oxide products, mainly used in the production of oriented silicon steel sheet, in its high temperature annealing stage, so that iron metal atoms into a regular orientation, to isolate and prevent sintering, remove sulfur and phosphorus in silicon steel impurities, but also with the surface of silicon steel The silicon reaction forms an excellent insulating film. In order to ensure the quality of magnesium oxide coating, there are special requirements for silicon steel magnesium oxide: (1) higher chemical purity; (2) It has good suspension performance in water, convenient coating operation, and prevents the deposition of magnesium oxide during the coating process; (3) Lower hydration rate, reducing annealing time, drainage time and the formation of iron oxides; (4) suitable activity; (5) The adhesion with the surface of the silicon steel sheet is strong. Process route: The production of electrical steel magnesium oxide mainly uses seawater brine and minerals as raw materials. In the production of liquid raw materials, alkaline solution is first used as a precipitating agent to precipitate magnesium, and then further prepare magnesium oxide. The brine ammonium carbide method with basic magnesium carbonate as the intermediate and the brine ammonia method with magnesium hydroxide as the intermediate are mainly used in China, and calcium hydroxide is mostly used as the precipitant in Japan and Israel.

At present, the magnesium oxide coating liquid is coated by a two-roll coating machine, which comprises an upper coating roller, a lower coating roller, a tray, a magnesium oxide coating liquid circulation device, and a nozzle spraying the magnesium oxide coating liquid in the magnesium oxide coating liquid circulation device to the upper surface of the iron steel, and the lower coating roller is immersed in the tray. The magnesium oxide coating liquid sprayed by the nozzle to the upper surface of the strip spills into the tray, and the lower coating roller uses the magnesium oxide coating liquid in the tray to coat the lower surface of the strip.

However, due to the magnesium oxide coating solution in the coating cycle process, the magnesium oxide solution in the tray does not flow smoothly, and magnesium oxide reacts with water to form magnesium hydroxide precipitation, and magnesium hydroxide combines with carbon dioxide in the air to form magnesium carbonate that is easy to precipitate. Magnesium carbonate and magnesium hydroxide have poor fluidity and are prone to agglomeration deposition. Therefore, the fluidity of the coating liquid in the tray is not high, and with the passage of time, the coating liquid is easy to accumulate and scale, resulting in poor coating quality of the lower coating roller, and double lines with different width and quantity appear along the strip rolling to the plate surface, and wear the lower coating roller, which directly causes product quality defects. In serious cases, it is also necessary to stop the machine to replace the coating roller, clean up the circulation pipe blockage, and deal with the scale of the tray. On the one hand, these unfavorable factors greatly increase the labor intensity of the staff, on the other hand, interfere with the continuous production of the site, directly affect the production efficiency, and because the cured magnesium oxide coating liquid can not be used in the tray, not only difficult to clean, but also cause waste of magnesium oxide. In addition, due to the liquid at the edge of the coating roll, the coating quality is affected, and the coating machine is interfered with, resulting in scale accumulation at the edge of the coating roll and uneven coating on the strip edge.