Mullite-Forming Chamotte Grogs
Chamotte grogs engineered to form mullite crystals upon firing, used in advanced refractories for petrochemical heaters. Classified under HTS 2508.70.00.00 as chamotte earths, these calcined clays remain unfinished raw materials. Their high purity supports consistent mullite development in end products.
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Alternative Classifications
This product could be classified differently depending on its characteristics or intended use.
If pure mullite mineral product
Naturally occurring or separated mullite falls under its specific 2508 subheading.
If synthetic mullite powder
Artificially produced aluminum silicates classify as chemical products in 2818.
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Import Tips & Compliance
• Provide XRD analysis showing mullite precursors; declare as 'calcined clay grog' explicitly; ensure no pre-firing to mullite phase to stay in 2508
Related Products under HTS 2508.70.00.00
Calcined Chamotte Refractory Clay
Calcined chamotte is a high-alumina fired clay aggregate used primarily in refractory brick manufacturing for high-temperature applications like furnace linings. It falls under HTS 2508.70.00.00 as chamotte earth, which is specifically defined as a type of dinas earth processed through calcination to achieve thermal stability. This material is not expanded and remains in granular or powdered form suitable for refractory production.
Dinas Earth Refractory Grogs
Dinas earth grogs are siliceous chamotte materials derived from quartzite clays, calcined for use as grog in high-silica refractories for steelmaking ladles. Classified under HTS 2508.70.00.00 due to its definition as dinas earth, a specific refractory clay not further manufactured. It provides skeletal structure in refractory mixes without being expanded or shaped.
High-Alumina Chamotte Powder
High-alumina chamotte powder, typically 50-70% Al2O3, is produced by calcining fireclay for addition to monolithic refractories and castables. It is classified in HTS 2508.70.00.00 as chamotte earth in powdered form, distinct from raw clays or finished articles. This ensures accurate duty application for bulk refractory raw materials.
Fireclay Chamotte Aggregates 70% Al2O3
Fireclay-based chamotte aggregates with 70% alumina content serve as coarse fractions in refractory concrete for kilns and incinerators. Under HTS 2508.70.00.00 as chamotte or dinas earths, these are calcined clays not expanded or otherwise manufactured beyond aggregation. They enhance volume stability in high-heat environments.
Siliceous Dinas Earth for Glass Furnace Refractories
Siliceous dinas earth, calcined from quartz-rich clays, is specialized for crown refractories in glass melting furnaces due to low thermal expansion. HTS 2508.70.00.00 captures it as dinas earths, excluding finished or expanded forms per chapter notes. Bulk granules ensure proper classification as raw refractory material.
Refractory Chamotte for Cement Kilns
Medium-duty chamotte refractory clay optimized for rotary cement kilns, offering abrasion resistance and thermal shock tolerance. HTS 2508.70.00.00 applies to this dinas earth variant in bulk aggregate form, per chapter exclusions for expanded or shaped goods. Essential for sustainable kiln lining formulations.