Aluminum hydroxide

Aluminum hydroxide (CAS 21645-51-2), also sold as hydrated alumina, is an inorganic mineral compound used across industrial and pharmaceutical markets as a flame retardant, antacid active, and catalyst precursor.

Its function shifts significantly by grade and particle size, making specification alignment critical at the sourcing stage. In plastics and polymer compounding, it acts as a halogen-free flame retardant and smoke suppressant.

The material is incorporated into cable jacketing, flooring, and construction panels to meet fire safety standards. Pharmaceutical manufacturers use it as an active ingredient in antacid formulations where it neutralizes excess gastric acid.

Sold historically under the brand Amphojel, it is used in OTC tablet and suspension products. In the paper and textile industries, it functions as a mordant and surface treatment agent, improving dye fixation and coating adhesion.

Catalyst producers also use it as a precursor for alumina-based catalysts applied in refining and chemical synthesis. The product is supplied as a fine white powder, with particle size and surface area varying by intended application.

Standard grades include USP and BP for pharmaceutical use, and technical or flame-retardant grades for industrial polymer applications. FCC-grade material is available for food-contact and food-additive applications.