U.S. exports of calcined or sintered dolomite (HS 251820) totaled $1.4M in August 2026.
Calcined or Sintered Dolomite imports of $653K in August 2026 ran 15% below the year-to-date monthly average of $773K.
Last updated: August 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.
97 shipments/mo
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.
HSChapter 25
ImportsExports
Imports
$653KYoY · free account
Exports
$1.4MYoY · free account
12-mo low · imports
YoY · free accountOver the twelve months to August 2026, the U.S. imported $10.0M of Calcined or Sintered Dolomite.
Through August 2026. Source: U.S. Census Bureau.
Trade Directory
List your company under HS 251820 — Calcined or Sintered Dolomite, so the companies trading it can find you. Be the first supplier listed.
Subheading 1 of 2 in heading 2518
Subheading 251820 · $1.4M of $1.5M
HS10 import codes under this HS6 parent, each with its own page. Source: U.S. Harmonized Tariff Schedule.
| Code | Description | Import Value | Effective Tariff % | Dutiable Share |
|---|---|---|---|---|
| 2518200000 | Dolomite Calcined or Sintered | $653K | 0.00% | 0.00% |
HS10 export codes under this HS6 parent, each with its own page. Source: U.S. Schedule B export classification.
| Code | Description | Export Value |
|---|---|---|
| 2518200000 | Dolomite Calcined or Sintered | $1.4M |
Import lines come from the U.S. Harmonized Tariff Schedule and export lines from Schedule B. The two are numbered by different agencies, so the same 10-digit code can appear in both tables describing a different product.
Exports · August 2026
destination
Canada and Mexico together take 99% of it.
customs district
origin
entry
rate provision · imports
100.0% enters free of duty; duty collected equals 0.00% of total import value.