What are the characteristics of

1、 Cao based calcium desulfurizer


Cao based desulfurizers used in many enterprises in China are mainly composed of lime w (CAO) = 90% and fluorite w (CaF2) = 5% ~ 10%. The addition of fluorite and Al into activated lime can significantly improve the desulfurization effect. At present, the desulfurizer used in Kr technology provided by Japan is about 5% fluorite, 10% Al, and the rest is activated lime. Lime is a very easy to get raw material with sufficient raw material and low price. However, lime based desulfurizer has a large amount of use, a large amount of slag, a long treatment cycle, and a high desulfurization efficiency when the hot metal temperature is high. Cao based desulfurizer was used in Kr process of No.2 Steelmaking Plant of WISCO after using CaC2 for several years.


2、 Mg and Mg based desulfurizer


The data show that the equilibrium constant of [Mg] and [S] is higher than that of calcium carbide and lime at 1350 ℃. However, magnesium and sulfur have a high affinity, the reaction zone kinetic conditions are very good, the reaction is rapid and very strong. The MGS produced by the reaction of magnesium with sulfur in hot metal has high melting point (2000 ℃) and low density (2.82g/cm3), which is easy to form slag. However, the activity of magnesium is very high, so it must be passivated as a desulfurizer.


Magnesium can not only separate desulfurization, but also use magnesium based composite 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, so that magnesium powder is evenly distributed in hot metal, which not only expands the reaction area, but also slows down the gasification rate 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), speed up the floating of inclusions, continuously reduce the sulfur concentration in the reflection area, and improve the desulfurization speed, which is conducive to achieving the requirements of rapid and deep desulfurization; sulfur and Cao, SiO2, etc. form calcium silicate salts with high thermodynamic stability, which are fixed in the slag, and are not easy to recover sulfur after slag removal; Moreover, about 10% of calcium oxide powder participates 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, China adopted the method of sprinkling soda into the blast furnace cast iron ditch for desulfurization. The liquid sodium oxide decomposed by soda has strong corrosiveness, and the volatilization of sodium oxide pollutes the environment. It is difficult to remove the slag due to its good fluidity. Soda prices are also relatively high. Therefore, soda as a desulfurizer has been very rare.


4、 CaC2 based calcium based desulfurizer


Calcium carbide (CaC2) has a strong desulfurization ability. The study shows that the equilibrium constant of calcium carbide powder desulfurization reaction is the highest when the temperature of molten iron is 1350 ℃. Calcium carbide, dry pulverized coal, magnesium or calcium oxide are widely used in industry. For example, CaC2 based desulfurizer was used in Panzhihua Iron and Steel Co. However, calcium carbide is very easy to react with the moisture in the air to produce acetylene gas, which is flammable and explosive. Therefore, the safety measures in the process of calcium carbide processing, transportation, storage and use are very high, resulting in processing difficulties. And it can not meet the requirements of deep desulfurization.