Magnesia and magnesite from China

Zero duty

Read from the UK Trade Tariff on 26 September 2026, natural magnesium carbonate (magnesite), fused magnesia of 94% or more purity and other fused magnesia, dead-burned (sintered) magnesia and other magnesium oxide of heading 2519 carried 0% duty on goods from China, with no anti-dumping measure.

Magnesium hydroxide, magnesium oxide of chemical purity and magnesium salts are chemicals of chapter 28, and magnesia bricks are in 6902, covered in our refractory bricks guide. Confirm the commodity code from the firing route and purity.

Grades by use

Dead-burned magnesia for refractory bricks and gunning mixes is bought on MgO content, the lime-to-silica ratio, iron and boron impurities and grain bulk density. Fused magnesia for tubular heating elements is bought on electrical insulation and particle size. Caustic calcined magnesia for agriculture, feed and effluent treatment is bought on MgO content and reactivity, often measured by a citric acid activity test.

Magnesia used as a feed material must meet feed law limits for undesirable substances such as heavy metals, so ask for an analysis for each lot. Magnesia picks up moisture and carbon dioxide from the air and hydrates, so it must be shipped in lined, sealed bags. An importer of more than one tonne a year should check UK REACH registration; see our UK REACH guide.

Worked duty example

Suppose, purely for illustration, you import 25 tonnes of dead-burned magnesia grain in bulk bags under 2519 90 30 00. At £12,000 free on board and £2,500 to ship and insure, the customs value is £14,500. With 0% duty on dead-burned magnesia, the only charge is import VAT: 20% of £14,500, or £2,900. VAT-registered businesses usually recover that in their next return. Magnesium hydroxide and chemically pure magnesium oxide are chemicals of chapter 28 instead. The method is set out in how UK import duty and VAT work.

What goes wrong

Magnesia fails on chemistry and hydration. MgO runs below the grade and silica or lime runs high, which lowers refractoriness; boron above the limit weakens hot strength; grain density is low so bricks are porous; caustic grades are over-burned and react too slowly; and damp storage hydrates the product so it swells and cakes.

Analyse each lot for MgO, CaO, SiO2, Fe2O3 and boron by XRF or wet chemistry against the grade, measure grain bulk density and loss on ignition, test reactivity on caustic grades, check particle size by sieving, and inspect bag liners and seals before loading.

Cambridge China Bridge sources dead-burned, fused and caustic calcined magnesia for refractory, heating element, agricultural and water treatment users, and can qualify a Chinese producer as a second source. See our second-supplier service.