What are the characteristics of common

1、 Cao based calcium desulfurizer


The Cao based desulfurizer used by many enterprises in China in the early stage is mainly composed of lime w (CAO) = 90% and fluorite w (CaF2) = 5% - 10%. Adding 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 active lime. Lime is very easy to get raw materials, raw materials are sufficient, and the price is cheap. However, the use of lime based desulfurizer is large, the amount of slag is large, and the treatment cycle is long. When the temperature of hot metal is high, the desulfurization efficiency is also high. Cao based desulfurizer was used in Kr process of WISCO's No.2 steelmaking plant after using CaC2 for several years.


2、 Mg and Mg based desulfurizer


The data show that the equilibrium constant of [Mg] and [S] reaction is not as high as 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. MGS formed by the reaction of magnesium and sulfur in molten iron has high melting point (2000 ℃) and low density (2.82g/cm3), which is easy to form slag. However, magnesium has a high activity and must be passivated as a desulfurizer.


Magnesium can be used not only for desulfurization alone, but also for 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 transportation of dense phase. The desulfurization reaction mechanism of the compound desulphurizer of magnesium and lime is as follows: due to the addition of lime, calcium oxide powder is wrapped and dispersed to make it 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 composite to polymerize the fine MGS (1-5 μ m) to accelerate the floating of inclusions, continuously reduce the sulfur concentration in the reflection area, and improve the desulfurization speed, which is conducive to the realization of the requirements of rapid and deep desulfurization; sulfur and Cao, SiO2 and other generate calcium silicate with high thermodynamic stability, which are fixed in the slag and are difficult to re sulfur after being removed by slag stripping; In addition, about 10% Cao powder participates in the desulfurization reaction; the sulfur in the desulfurized slag is not easy to be dissolved and washed out by water, which does not pollute the environment and creates conditions for the convenient treatment or development and utilization of the slag.


3、 NaCO3 based sodium desulfurizer


In China, soda was sprayed into the tap hole of blast furnace for desulfurization in 1950s. The liquid sodium oxide decomposed by soda has strong corrosivity, and the volatilization of sodium oxide pollutes the environment. It is difficult to remove slag because of its good fluidity. Soda prices are also relatively high. Therefore, soda as a desulfurizer has been very rare.


4、 CaC2 based calcium desulfurizer


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