Nickel sulfate falls under 283324 and is a critical input for lithium-ion battery cathode precursor manufacturing. Because China is a significant producer, Section 301 tariffs may apply to Chinese-origin material, making origin verification and potential supply-chain diversification important for battery-sector importers.

Alums are double sulfates containing both a monovalent cation (such as potassium or ammonium) and a trivalent cation (typically aluminum), crystallizing in a specific hydrated form. They classify under 283330 rather than the metal-specific sulfate subheadings, even though they contain sulfate anions, because their double-salt character is the defining feature.