Nodulizers and inoculants are important materials in the spheroidization process. In addition to stable quality, the following factors need to be considered when selecting a suitable nodulizer.
Nodulizer
Spheroidization treatment temperature: If the spheroidization treatment temperature is >1480°C, the spheroidization reaction will be more intense, resulting in a lower magnesium absorption rate. In order to make the spheroidization reaction stable, you can choose a spheroidizer with a relatively high calcium content. If the spheroidizing temperature is <1480°C, a spheroidizing agent with a relatively lower calcium content can be used.
Processing bag size: If the height-to-diameter ratio of the processing bag is 1:1, the magnesium absorption rate will decrease due to the loss of magnesium vapor, and it is recommended to use a nodulizer with higher calcium content. If the height-to-diameter ratio of the treatment bag is 2:1, the spheroidization reaction will be relatively stable, the magnesium vapor will diffuse into the molten iron, and the magnesium absorption rate will be improved.
Spheroidization process: If the cover bag method is not used, the smoke generated by the spheroidization reaction will enter the atmosphere and produce dazzling white light. In order to make the spheroidizing reaction stable, a spheroidizing agent with low magnesium and high calcium can be used. If the cover bag method is used, the molten iron will not splash and produce less smoke. A nodulizer with high magnesium and low calcium can be used to reduce the dosage and reduce the cost of nodularization.
Processing weight: If the weight of molten iron to be processed is less than 500kg, then a nodulizer with a smaller particle size can be used, and a nodulizer with a particle size below 12mm is recommended. If the weight of molten iron to be processed is 500~1000kg, a nodulizer with a larger particle size can be used, such as a nodulizer with a particle size of 3~25mm. If the weight of molten iron to be processed is greater than 1000kg, nodulizers of 4~32mm can be used.
Silicon content: If the process yield rate of casting products is low or the scrap rate is high, it is desired to add more charge and scrap steel for smelting, and castings have strict requirements on the silicon content of molten iron. On the premise that the amount of inoculation cannot be further reduced, low-silicon spheroidizers can be used for treatment, which can increase the return charge by 8% to 15%, which can reduce the production cost of the foundry.
Sulfur content of raw iron liquid: If the sulfur content of raw iron liquid is high, if desulfurization treatment is not carried out, nodulizers with high magnesium and rare earth are required, and the addition amount will be relatively high. If the sulfur content of raw iron liquid is low, then Low-magnesium and low-rare-earth nodulizers can be used, and the addition amount will be relatively low, and the cost of low-magnesium and low-rare-earth nodulizers will also be relatively cheap.