Selection Of Equipment And Raw Materials in Ductile Iron Process

1 Device selection

Selection of smelting equipment The first choice of smelting equipment is to follow the principles of high efficiency and low consumption under the premise of meeting production needs. The advantages of induction furnace are: fast heating speed, high thermal efficiency of the furnace, light oxidation burning loss, and less gas absorption. Therefore, smelting with an intermediate frequency electric furnace can avoid the problems of increasing sulfur and phosphorus, so that P in the molten iron is not more than 0.07% and S is not more than 0.05%. Determination of spheroidizing bag In order to improve the absorption rate of the spheroidizing agent and increase the spheroidizing effect, the spheroidizing treatment bag should be deeper than the general molten iron bag. The height to diameter ratio of the spheroidized package was determined to be 2:1.

2 Raw material selection

The conditions for adding effect of ductile iron nodularizing agent for charge selection are: high carbon, low silicon, and large inoculation. In order to stabilize the chemical composition and effectively control the elements that promote whitening and de-spheroidization, and ensure the quality of molten iron, high-quality Z14 pig iron is selected. Its chemical composition: C>3.3%, Si 1.25%～1.60%, P≤0.06% , S≤0.04%, with high-quality scrap steel and graphitized petroleum coke recarburizer for smelting.

Selection of Nodulizer The selection of nodulizer should be determined according to the different smelting equipment, that is, the tapping temperature and the purity of the molten iron (such as sulfur content, degree of oxidation, etc.). The most commonly used in my country is the rare earth magnesium ferrosilicon nodularizer. When this nodulizer is used, due to the high content of silicon in the alloy, the severity of the reaction during magnesium treatment can be significantly reduced. At the same time, it can also have some breeding effect due to silicon addition. During electric furnace production, due to the relatively high temperature, the nodulizer FeSiMg8Re7 is used.