In industrial realm, adding calcium in steelmaking is a pivotal process that enhances the quality and performance of the final product. This method involves introducing calcium-containing materials into the steelmaking furnace, where it undergoes a series of reactions crucial for refining the steel. The addition of calcium serves multiple purposes, including deoxidation, desulfurization, and modification of inclusions, leading to a more robust and homogeneous steel structure. Its effectiveness in reducing impurities and increasing steel cleanliness makes it an indispensable technique in modern steel production, ensuring the end product meets stringent industry standards. In this article, we will introduce about adding calcium methods in steelmaking.
Content
Ca physical property and evolution of adding calcium methods
Physical property
From below table 1, we can clearly see that its melting and boiling point are below 1600℃——molten steel’s approximate temperature. According to this characteristic and its solubility in molten iron, it is easy to vaporize in liquid steel and escape. It affects the effect of calcium treatment seriously. Therefore, it is pivotal for calcium recovery consummation to optimize addition methods.
| Element | Melting point /℃ | Boiling point /℃ | Vapour pressure (1600℃/MPa) | Solubility in molten iron (1600℃/0.1MPa)/% |
|---|---|---|---|---|
| Ca | 839 | 1484 | 0.184 | 0.017 |
Table 1 Ca physical property
Addition methods
For steel plant, mainly have 4 adding calcium methods:
- Direct addition method
- Injection addition method
- Catapult addition method
- Wire feeding method
Direct addition method:
Direct addition method, as the name implies, it is a technique that adding calcium alloy and deoxidizer into molten steel directly. In early era, most of steel plants use this method to perform calcium treatment process in actual producing, because relevant studies for calcium treatment progressed slowly and technology less developed. While calcium recovery lower and effect worse used this method. It is early rudiment for calcium treatment.
Injection addition method:
Injection addition method is a kind of calcium addition technique that Ca injected into bottom of the ladle by powder injecting lance. According to description, we can see that Ca injected into bottom of the ladle directly. Compared with direct addition method introduced above, it can combine calcium and molten steel more effectively and sufficiently. And then, improve calcium recovery. But every coin has two sides, costs of this method is expensive and bring in H、O and any other impurities into steel easily. It makes more difficult to control compositions of molten steel. Thus, this method is eliminated by most of steel plants nowadays.
Catapult addition method:
If you are not metallurgist or student, practitioner in relevant industrial realm, maybe you will think that it is unique when you listening to its name firstly. Actually, it is a technique that inject Ca into liquid steel with high speed using catapult equipment. It makes calcium melt in deep of molten steel by high speed injection, so that improving calcium recovery. Using this method can get higher calcium recovery, [Ca] in molten steel can reach to 0.003% – 0.005%.
Wire feeding method:
Wire feeding method is also called WF method, it utilizes wire feeding machine to feed calcium cored wire into molten steel with higher speed. After outer steel strip melting, inner calcium is fed into deep of molten steel. And achieving the goal that deoxidize, desulphurize, remove inclusions and improve cleanliness.
Calcium recovery using wire feeding method is higher among above 4 methods. It is easy to control feeding position, path and speed for cored wire, thus, in contemporary society, most of steel plants use this method, so that it is used more widely in calcium treatment process.
Conclusion
In summary, the addition of calcium in steelmaking is instrumental for refining steel quality. Its diverse functions, from deoxidation to inclusion modification, result in a superior steel structure. This method’s effectiveness in purifying steel and meeting industry standards underscores its crucial role in modern production.
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