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HSChapter 25
U.S. imports of calcined or sintered dolomite (HS 251820) totaled $710K in April 2026, traded with 4 countries.
Calcined or Sintered Dolomite imports of $710K in April 2026 ran 19% below the year-to-date monthly average of $881K.
Last updated: April 2026 dataCalcined and sintered dolomite — produced by firing raw dolomite at high temperatures to yield a reactive mixture of magnesium oxide and calcium oxide — is a critical refractory and steelmaking input classified under tariff line 2518200000. Canada is the primary US supplier, with Vietnam an increasingly significant source reflecting Asia's growing refractory materials export capacity. The calcination or sintering process fundamentally changes the mineral's reactivity and density, making it suitable for furnace linings and slag conditioning in electric arc and basic oxygen steelmaking. Importers should verify the degree of calcination (caustic-calcined versus dead-burned) as this affects both end-use suitability and potential reclassification into heading 2519.
AI-written summary of the official U.S. Census Bureau trade figures on this page — verify before relying on it.
Calcined dolomite (2518200000) retains both magnesium oxide and calcium oxide in its structure after firing and is used primarily as a refractory flux in steelmaking. Dead-burned magnesia (classified under heading 2519) is a more intensely sintered product with very high MgO content and extremely low reactivity, used for high-temperature refractory bricks. The MgO-to-CaO ratio and sintering temperature are the key differentiators for both classification and commercial specification.
Importers should request a mill certificate or certificate of analysis from the supplier specifying the calcination temperature, loss on ignition (LOI) value, and chemical composition (MgO and CaO percentages). A low LOI confirms that CO₂ has been driven off through calcination, distinguishing the product from uncalcined dolomite under 2518100000.
Monthly import values over time
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HS10 import codes under this HS6 parent. Source: U.S. Harmonized Tariff Schedule.
| Code | Description | Import Value | Effective Tariff % | Duty Collected |
|---|---|---|---|---|
| 2518200000 | DOLOMITE CALCINED OR SINTERED | $710K | 13.00% | $6K |
DOLOMITE CALCINED OR SINTERED
HS10 export codes under this HS6 parent. Source: U.S. Schedule B export classification.
| Code | Description | Export Value |
|---|---|---|
| 2518200000 | DOLOMITE CALCINED OR SINTERED | $1.0M |
DOLOMITE CALCINED OR SINTERED
4.7K t
PORTLAND CEMENT EXCEPT WHITE PORTLAND CEMENT
HS 252329
SULFUR OF ALL KINDS, NOT SUBLIMED,PRECIP,COLLOIDAL
HS 250300
SALT INCL TBL/DENTRD, PURE SODM CHLOR ETC; SEA WTR
HS 250100
UNGRND NAT CAL PHSPH, ALUM CAL PHOS A PHOS CHALK
HS 251010
FLUORSPAR OV 97% OF CALCIUM FLUORD BY WGHT
HS 252922
PEBBLES, GRAVEL ETC. FOR CONCRETE AGGREGATES ETC.
HS 251710
| Port | Imports | Exports | Balance |
|---|---|---|---|
| EASTPORT, ID | -- | $578K | +$578K |
| DETROIT, MI | $273K | $67K | -$206K |
| BUFFALO-NIAGARA FALLS, NY | $325K | $5K | -$319K |