Synthetic Mullite Powder
Synthetic mullite powder is a high-alumina ceramic material produced by sintering or fusing alumina and silica, used primarily in refractory applications. It falls under HTS 2508.60.00.00 as mullite, a specific aluminosilicate mineral classified among other clays and earths, whether or not calcined.
Import Duty Rates by Country of Origin
Alternative Classifications
This product could be classified differently depending on its characteristics or intended use.
If artificial corundum with less than 50% silica
High-alumina synthetic materials resembling corundum are classified under artificial corundum heading rather than natural clays.
If shaped into refractory bricks or blocks
Pre-formed mullite refractories are finished ceramic goods under Chapter 69, not raw earths.
If chemically defined prepared binders containing mullite
Mullite in chemical preparations or mixtures for foundry use falls under chemical products, not mineral earths.
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Import Tips & Compliance
• Verify purity and chemical composition via lab certification to confirm mullite classification and avoid reclassification as synthetic corundum
Related Products under HTS 2508.60.00.00
Calcined Mullite Aggregate
Calcined mullite aggregate consists of crushed and heat-treated mullite grains used as a raw material in high-temperature refractories and castables. Classified under HTS 2508.60.00.00 as calcined mullite among other refractory earths.
Mullite Chamotte Grogs
Mullite chamotte grogs are fired, crushed mullite particles used as aggregate in refractory brick formulations. Classified under HTS 2508.60.00.00 alongside chamotte or dinas earths as processed refractory materials.
Bauxite-Derived Calcined Mullite
Bauxite-derived calcined mullite is produced by calcining bauxite to form the mullite phase, used in abrasive refractories. HTS 2508.60.00.00 covers this as calcined mullite distinct from raw bauxite ores.
Micronized Mullite Flour
Micronized mullite flour (D50 <5μm) serves as a fine filler in technical ceramics and casting slips. Remains under HTS 2508.60.00.00 as processed mullite powder, not chemical preparations.
Fused Mullite Grain 200 Mesh
Fused mullite grain in 200 mesh size is electrically fused mullite for precision casting molds and advanced ceramics. It qualifies under HTS 2508.60.00.00 as processed mullite, not excluding fusion per chapter provisions.
High Purity Mullite for Investment Casting
High purity mullite specifically graded for investment casting shells provides thermal stability and low thermal expansion. Falls under HTS 2508.60.00.00 as specialized mullite earth for industrial refractory use.