How To Improve The Absorption Rate Of Recarburizer When Smelting Gray Iron in An Intermediate Frequency Furnace? (2)

Therefore, the use of recarburizers and the effect of recarburization should be emphasized in actual production:

①The absorption rate of recarburizer is directly related to its C content. The higher the C content, the higher the absorption rate.

②The particle size of the carburizer is the main factor affecting its dissolution into molten iron. Practice has proved that the particle size of the recarburizer should be 1~5mm, and the effect of micro powder and coarse particles is not good.

③Si has a great influence on the effect of carburization. High-silicon molten iron has poor carburization performance and slow carburization rate. Therefore, ferrosilicon should be added after the carburization is in place, and the principle of adding carbon first and then adding silicon should be followed.

④Sulfur can hinder the absorption of carbon, and the carbon increase rate of high-sulfur molten iron is much slower than that of low-sulfur molten iron.

⑤ Graphite carburizer can improve the nucleation ability of molten iron, and the absorption rate is more than 10% higher than that of non-graphite carburizer, so low nitrogen graphite carburizer should be selected.

⑥ The method of using the carburizer is recommended to use the charging method with the furnace, that is, first add a certain amount of small pieces of return material and scrap steel to the bottom of the furnace, then add all the recarburizer according to the amount of ingredients, and press a layer of small piece steel scrap and pig iron, then added to the charge as they are melted. This method is simple and easy to implement, with high production efficiency, and the absorption rate can reach 90%. If the amount of recarburizer added is large, it can be added in two batches, first adding 60%~70% to the bottom layer of scrap steel, and adding the rest in the process of continuing to add scrap steel. When the temperature of molten iron is 1400~1430 ℃, carburizer can also be added, and the goal is to increase the C content of molten iron to reach the upper limit of the grade requirement.

⑦ The addition time of the carburizer should not be too late. Adding the carburizer in the later stage of smelting has two disadvantages: First, the carburizer is easy to burn and the carbon absorption rate is very low. Second, the carburizer added later requires additional melting and absorption time, which delays chemical composition adjustment and heating time, reduces production efficiency, increases power consumption, and may bring harm caused by excessive heating.

⑧The stirring of molten iron can promote the carbon increase, especially the graphite group attached to the furnace wall. If it is not overheated and the molten iron is kept warm for a certain period of time, it is not easy to dissolve in the molten iron. The strong electromagnetic stirring in the intermediate frequency furnace is beneficial to the carbon increase. 

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