Calcined Andalusite 55% Al2O3
Calcined andalusite with 55% alumina content is heat-treated to convert partially to mullite, improving thermal shock resistance. HTS 2508.50.00.00 covers this calcined form before further processing into finished refractories.
Import Duty Rates by Country of Origin
Alternative Classifications
This product could be classified differently depending on its characteristics or intended use.
If fully converted to mullite crystals
Leucite and other synthetic aluminosilicates including fully calcined mullite classify separately.
If pebbles/gravels sized under 256mm
Chapter note prioritizes heading 2517 for all such products over other Chapter 25 headings.
If expanded through high-temperature bloating
Expanded clays specifically excluded from Chapter 25 per heading exclusions.
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Import Tips & Compliance
• Alumina content certificates mandatory; discrepancies lead to 2529 reclassification
• Declare calcination temperature (typically 1300-1500°C) to confirm processing level
• Bulk bag labeling must specify 'not for expanded clay production' per statistical notes
Related Products under HTS 2508.50.00.00
Calcined Kyanite Powder
Calcined kyanite is a high-alumina aluminosilicate mineral processed by heating to stabilize its crystal structure, preventing volume expansion during ceramic firing. It is classified under HTS 2508.50.00.00 as calcined kyanite, a form of sillimanite group mineral used primarily in refractory and ceramic applications.
Raw Andalusite Ore
Raw andalusite ore consists of natural andalusite crystals extracted from deposits, typically containing 55-60% alumina. Classified under HTS 2508.50.00.00 as uncalcined andalusite, it serves as a raw material for refractory bricks and high-temperature ceramics.
Sillimanite Grain for Refractories
Sillimanite grains are crushed and sized particles of sillimanite mineral (Al2SiO5) used in refractory castables and ramming mixes. This product falls under HTS 2508.50.00.00 as unprocessed sillimanite, valued for its high melting point above 1600°C.
Kyanite Flour -325 Mesh
Ultra-fine kyanite flour (-325 mesh, <44 microns) used as filler in porcelain insulators and spark plugs. Classified under HTS 2508.50.00.00 as ground kyanite, not chemically modified.
South African Andalusite Lumps
Andalusite lumps from South African Namaqualand deposits, sized 10-100mm, containing 58% Al2O3. HTS 2508.50.00.00 applies to this natural uncalcined mineral export product used globally in steel ladle refractories.
Mullite-Forming Kyanite Concentrate
Beneficiated kyanite concentrate selected for optimal mullite formation during firing, 99%+ purity. Falls under HTS 2508.50.00.00 as processed but uncalcined kyanite per Chapter 25 definitions.