2522 - Quicklime, slaked lime and hydraulic lime, other than calcium oxide and hydroxide of heading 2825:

This HTS category, 2522, encompasses various forms of lime essential for industrial and construction applications. Specifically, it covers quicklime (calcium oxide), slaked lime (calcium hydroxide), and hydraulic lime. These products are derived from the calcination of limestone and other calcium carbonate-rich materials, undergoing distinct processing to achieve their specific chemical and physical properties. Quicklime, produced by heating limestone, is highly reactive, while slaked lime is formed by adding water to quicklime. Hydraulic lime, a more specialized product, possesses the ability to set and harden underwater due to the presence of clay impurities in its raw material.

Distinguishing this category from its siblings at Section V, Chapter 25 is crucial for accurate classification. While other Chapter 25 headings cover natural minerals and raw materials like salt, sulfur, earths, stone, plastering materials, and cement, heading 2522 specifically addresses manufactured lime products. Unlike basic mineral aggregates or cements which may have different chemical compositions and primary uses, the lime products in 2522 are characterized by their high calcium oxide content and their specific reactivity or setting properties, making them distinct for their intended applications in agriculture, metallurgy, chemical manufacturing, and construction.

Within heading 2522, further subclassification is provided to differentiate the specific types of lime based on their processing and chemical state. The subcategory 2522.10.00.00 covers quicklime, the initial calcined product. 2522.20.00.00 identifies slaked lime, resulting from the hydration of quicklime. Finally, 2522.30.00.00 is reserved for hydraulic lime, which exhibits cementing properties even in the presence of water, due to the controlled addition of silicates and aluminates during its production or inherent in the raw limestone. These distinctions are vital for determining specific tariff rates and regulatory requirements.