Mullite-Forming Chamotte Grogs
Chamotte grogs engineered to form mullite crystals upon firing are calcined clays used in advanced refractories for petrochemical heaters. These grogs are chamotte earths in an unfinished raw state, within the scope of Chapter 25 as they have not been processed beyond crushing, grinding, or calcination.
Import Duty Rates by Country of Origin
| Origin Country | MFN Tariff | Surtaxes | Total Effective Rate |
|---|---|---|---|
| 🇨🇳China | Free | — | Free |
| 🇲🇽Mexico | Free | — | Free |
| 🇺🇸United States | Free | — | Free |
| 🇩🇪Germany | Free | — | Free |
| 🇯🇵Japan | Free | — | Free |
More Specific Codes
This product may fall under a more specific subheading:
Alternative Classifications
This product could be classified differently depending on its characteristics or intended use.
If the product is already mullite rather than a chamotte that forms mullite
Mullite is specifically classified under its own tariff item.
If the grogs are incorporated into finished refractory articles containing mullite
Finished refractory articles are classified under ceramic products.
Not sure which classification is right?
The Tariff Assistant works through the GRI rules on your specific product to reach the right tariff item — and can price the duty on it in the same conversation.
Import Tips & Compliance
• Ensure the grogs are not pre-fired to the mullite stage, as mullite itself is classified under a separate heading (2508.60.00)
• Provide technical data showing the grogs are designed to form mullite only upon further firing by the end user
• Verify the product has not been mixed with other oxides or additives
Related Products under Tariff item 2508.70.00
Calcined Chamotte Refractory Clay
Calcined chamotte is a high-alumina fired clay aggregate produced by calcining fireclay at high temperatures. It is used primarily as a raw material in refractory brick manufacturing for furnace linings, and remains in a crude or processed state consistent with Chapter 25 note 1.
Dinas Earth Refractory Grogs
Dinas earth refractory grogs are siliceous chamotte materials derived from quartzite clays and calcined for use as grog in high-silica refractories for steelmaking ladles. They are crude or processed mineral products within the scope of Chapter 25, specifically classified as dinas earths.
Fireclay Chamotte Aggregates 70% Al2O3
Fireclay-based chamotte aggregates with 70% alumina content are calcined clays used as coarse fractions in refractory concrete for kilns and incinerators. These aggregates are chamotte earths in crude or processed form, not exceeding the processing allowed by Chapter 25 note 1.
High-Alumina Chamotte Powder
High-alumina chamotte powder, typically 50-70% Al2O3, is produced by calcining fireclay and grinding it to a powder for addition to monolithic refractories and castables. It is classified as chamotte earth in powdered form, a product of Chapter 25 that has undergone only mechanical processing.
Refractory Chamotte for Cement Kilns
Medium-duty chamotte refractory clay optimized for rotary cement kilns is a calcined clay aggregate offering abrasion resistance and thermal shock tolerance. It is classified as chamotte earth in bulk aggregate form, consistent with Chapter 25 note 1 as it has not been processed beyond calcination and mechanical treatment.
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 its low thermal expansion. It is classified as dinas earths under tariff item 2508.70.00, as it is a crude mineral product that has not been processed beyond calcination and mechanical treatment.