What are the characteristics of

1、 Cao based calcium desulfurizer


The Cao based desulfurizer used in many enterprises in China in the early stage was mainly lime w (CAO) = 90% and fluorite w (CaF2) = 5% ~ 10%. Adding fluorite and Al into active lime can significantly improve the desulfurization effect. At present, the desulfurizer used in Kr technology provided by Japan is about 5%, Al is 10%, and the rest is active lime. Lime is very easy to get raw materials, sufficient raw materials and cheap price, but the use of lime-based desulfurizer is large, the amount of slag is large, the treatment cycle is long, and it also shows high desulfurization efficiency when the hot metal temperature is high. In the Second Steelmaking of WISCO, the Kr desulfurization method was changed to Cao based desulfurizer after using CaC2 for several years.


2、 Mg and Mg based desulfurizer


The data show that the equilibrium constant of the reaction between [Mg] and [S] at 1350 ℃ is not as high as that of calcium carbide and lime. But the metal magnesium has a very high affinity with sulfur. The reaction zone has a very good kinetic condition, and the reaction is rapid and very strong. The melting point of MGS is high (2000 ℃), the density of MGS is low (2.82g / cm3), and it is easy to form slag. But the activity of magnesium is very high, so it must be passivated as desulfurizer.


Magnesium can not only desulfurize alone, but also use magnesium based compound desulfurizer. Magnesium powder used for Mg based desulfurizer is also passivated. The magnesium powder is made by milling cutter or spray, and the diameter is between 0.15 ~ 1.2mm, w (Mg) =90%, and the rest is passivation coating. The fluidity treated calcium oxide powder is mixed with magnesium powder to ensure smooth dense phase transportation. The desulfurization reaction mechanism of magnesium and lime composite desulfurizer is as follows: due to the addition of lime, calcium oxide powder is wrapped and dispersed to make it evenly distributed in molten iron, which not only enlarges the reaction area, but also slows down the gasification speed of magnesium and improves the utilization rate of magnesium; Cao can be used as the core of the complex to polymerize the fine MGS (1-5 μ m), accelerate the floating of inclusions, continuously reduce the concentration of sulfur in the reflecting area, and improve the desulfurization speed, which is conducive to the requirements of rapid deep desulfurization; sulfur, Cao, SiO2 and other calcium silicate salts with high thermodynamic stability are fixed in the slag, and it is difficult to recover sulfur after removing the slag; Moreover, about 10% calcium oxide powder takes part in the desulfurization reaction; the sulfur in the desulfurization slag is not easy to be dissolved and washed out by water, and does not pollute the environment, which creates conditions for the convenient treatment or development and utilization of the slag.


3、 NaCO3 based sodium desulfurizer


In the 1950s, the method of desulfuration was adopted in our country. The liquid sodium oxide decomposed by soda has strong corrosiveness, and the sodium oxide volatilizes to pollute the environment. It is difficult to remove slag because of the good fluidity of the slag produced by desulfuration with soda. Soda prices are also relatively high. Therefore, soda as desulfurizer is very rare.


4、 CaC2 based calcium desulfurizer


Calcium carbide (CaC2) has a strong desulfurization ability. The results show that the equilibrium constant of calcium carbide powder desulfurization reaction is the highest when the hot metal temperature is 1350 ℃. Composite desulfurizer such as calcium carbide, dry coal powder, magnesium or calcium oxide is widely used in industry, for example, CaC2 based desulfurizer has been used in Pangang. However, calcium carbide is very easy to react with the moisture in the air to generate acetylene gas, which is flammable and explosive. Therefore, the safety measures in the process of processing, transportation, storage and use of calcium carbide are very demanding, resulting in processing difficulties. And it can not meet the requirements of deep desulfurization.