High-Calcium Limestone Flux from Canada
High-calcium limestone flux is a coarsely crushed calcareous stone with at least 95% calcium carbonate content, specifically used in blast furnaces to remove impurities during steel production. It falls under HTS 2521.00.00.00 because it is limestone of a kind used for lime or cement manufacture, distinguished by its chemical purity and fluxing properties. This raw material is essential for slag formation in metallurgical processes.
Duty Rate — Canada → United States
Rate breakdown
Import Tips
• Verify chemical composition certificates showing high CaO content to confirm classification under 2521.00.00.00 and avoid misclassification as general crushed stone
• Ensure documentation specifies end-use for lime/cement manufacture, as flux properties must be evidenced for duty-free entry in some cases
• Watch for particle size specs; overly processed stone may shift to heading 2522 if not raw flux material