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Why is calcium preferred over sodium in some metal-processing applications?

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A labeled diagram of the periodic table entry for calcium, showing its atomic number 20, symbol Ca, atomic weight 40.078, electron configuration, and classification as an alkaline-earth metal. Icons indicate calcium is a solid with a face-centered cubic crystal structure and strongly basic oxides at room temperature. — calcium The chemical element calcium is the most abundant metallic element in the human body.

In metal-processing applications, calcium is often preferred over sodium as a reducing, deoxidizing, and degasifying agent primarily due to its lower volatility.1

While sodium is a highly effective and commonly used reducing agent for the preparation of various transition metals, such as titanium and zirconium, calcium’s lower volatility makes it more advantageous in specific industrial processes. Additionally, calcium is utilized in steel production for inclusion shape control; by forming stable calcium sulfide inclusions that remain non-plastic at hot-rolling temperatures, it helps improve the physical properties of the steel in directions perpendicular to rolling.213

Although calcium is generally more expensive and less reactive than sodium, its unique chemical properties make it a preferred choice for producing metals like chromium, thorium, and uranium from their oxides.1