Chapter 2521 — Customs Tariff Headings
Products classified under Tariff item 25.21
Cement Kiln Feed Limestone
Cement kiln feed limestone is a medium-to-coarse crushed calcareous rock selected for its consistent calcium carbonate content, used directly in rotary kilns for clinker production. It falls under this tariff item as calcareous stone of a kind used for the manufacture of cement, as permitted by the chapter notes for crushed or ground products.
2521.00.00Chemical-Grade Flux Limestone
Chemical-grade flux limestone is an ultra-pure calcareous stone with consistent calcium source, used in chemical processes like precipitated calcium carbonate production. It qualifies under this tariff item as limestone of a kind used for lime manufacture, given its high purity and intended use.
2521.00.00Fluxing Calcareous Stone for Steel Mills
Fluxing calcareous stone for steel mills is coarse angular stone sized 1-4 inches, used in basic oxygen furnaces to form slag. It falls under this tariff item as limestone flux, a calcareous stone used for lime-related industrial processes, and is not processed beyond crushing or sizing.
2521.00.00Glass Manufacturing Calcareous Stone
Glass manufacturing calcareous stone is used in soda-lime glass production to stabilize the network. It is classifiable under this tariff item as calcareous stone of a kind used for lime manufacture, since the soda-lime process involves lime as a key component, and the stone is not processed beyond crushing.
2521.00.00High-Calcium Limestone Flux
High-calcium limestone flux is coarsely crushed stone with at least 95% calcium carbonate, used in blast furnaces to remove impurities. It falls under this tariff item as limestone flux, a calcareous stone for lime-related metallurgical processes, and is not processed beyond crushing or screening.
2521.00.00Hydrated Lime Manufacturing Limestone
Hydrated lime manufacturing limestone is high-brightness stone suitable for producing hydrated lime for construction and chemicals. It falls under this tariff item as raw material expressly for lime production, and is not processed beyond crushing or grinding per chapter note 1.
2521.00.00Lime Production Quarry Limestone
Lime production quarry limestone is quarry-run blocks or crushed stone from high-purity deposits, intended for quicklime production via calcination. It is classifiable under this tariff item as calcareous stone of a kind used for lime manufacture, as it is in crude or crushed state.
2521.00.00Portland Cement Raw Limestone
Portland cement raw limestone is raw limestone chunks crushed to 3-6 inches for grinding into cement raw meal. It falls under this tariff item as calcareous stone used in cement production, and is not processed beyond crushing, as allowed by chapter note 1.