2621.90.00.00 - Other

This HTS category, 2621.90.00.00, encompasses a broad range of miscellaneous slag and ash not otherwise specified. It serves as a residual category for slag and ash that do not fit into more specific classifications within Chapter 26. Notably, this includes ash derived from seaweed, commonly known as kelp ash, which possesses unique properties and uses.

It is crucial to distinguish this residual category from its sibling, 2621.10.00.00, which specifically covers ash and residues resulting from the incineration of municipal waste. While both fall under the umbrella of slag and ash, 2621.90.00.00 is for materials not originating from municipal waste incineration, such as industrial slags or ash from the combustion of non-municipal waste materials.

As this is a leaf node in the HTS structure, there are no further subdivisions. Therefore, classification under 2621.90.00.00 relies on a thorough examination of the material's origin, composition, and the absence of a more specific tariff provision. Examples could include ash from the smelting of non-ferrous metals, slag from metallurgical processes not otherwise specified, or ash from the controlled burning of agricultural byproducts, provided they do not meet the criteria for incineration of municipal waste.