Hebei Messi Biology Co., Ltd. stated that with the development of China’s power industry, there are higher requirements for the iron cores of transformer motors and generators. Many large steelmaking enterprises in China have or are establishing silicon steel sheet production lines. With the increase in silicon steel production, the demand for silicon steel grade magnesium oxide with higher purity is also increasing. Silicon steel grade magnesium oxide is a coating material used in the high temperature annealing stage of oriented silicon steel. It can play the role of isolation, desulfurization, etc., and form an insulating film on the surface of silicon steel.
At present, there are two main methods for preparing magnesium oxide: one is to use seawater as raw material. Add alkaline substances to precipitate magnesium in the form of magnesium hydroxide, and then calcine it; the other is to use magnesite and dolomite as raw materials, carbonize it with basic magnesium carbonate as an intermediate, and then calcine it. Solids as raw materials will be accompanied by impurities such as calcium and iron, so the impurity removal process is particularly important in the process of preparing high-quality magnesium oxide.
Silicon steel grade magnesium oxide should have the following special qualities: high chemical purity; good suspension performance in water; low hydration rate and certain activity; strong adhesion to the surface of silicon steel sheet. Among them, high chemical purity is particularly important. Silicon steel grade magnesium oxide must meet the quality technical indicators of (MgO)>98%, (Ca0)<0.5%, and (iron)<0.05%. Metal impurities such as iron are important factors affecting the whiteness and product quality of magnesium oxide, so iron removal and calcium removal are more important in the process of preparing silicon steel grade magnesium oxide.
The commonly used iron removal method is mainly the oxidation-reduction method, but the precipitation is extremely difficult to handle: activated carbon is also used for impurity removal. Although the effect is very good, the activation problem of activated carbon puts high demands on the entire production process and is difficult to achieve industrial production. The impurity calcium is also mostly removed by precipitation. However, due to the similar properties of calcium and magnesium, the impurity removal effect is not ideal. In view of the shortcomings of the above impurity removal methods, it is proposed to use complexing agents for impurity removal. Since the chelating agent reacts with iron and calcium to make them exist in the solution in the form of a complex, basic magnesium carbonate can be separated from them during pyrolysis; this method not only has a good impurity removal effect, but also has a simple and convenient process and is more suitable for industrial production.