Calcium addition to steel improves its properties in several ways, including fluidity, cleanliness, and impact strength. It is added to cast irons and steels in the form of calcium silicon alloys or calcium carbide. The process requires agitation to remove the gas content from the liquid metal, and results in more uniform and sound cast structures.
Calcium carbide is a gray or black substance with a chemical formula of Ca C 2. Friedrich Wohler first discovered the chemical reaction between calcium carbide and water in 1862. This compound is a powerful deoxidizer at ladle treatment facilities. It is also used in the manufacture of acetylene.
Ca alloy has high melting and boiling points, but this is not the primary factor. Its high melting point allows it to be a good agitator for liquid steel. However, Ca does not melt very easily in steel and therefore is often present in lumps. Its high melting point and low solubility make it difficult to introduce into the steel melt.
The texture of limestone is also important. Softer limestones produce more limestone fines than harder ones. The chemical content of the stone also affects the calcination process. If the stone is very hard, it may break during the process.
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