Magnesia, fused or dead-burned (sintered); whether or not containing small quantities of other oxides added before sintering, other magnesium oxide, whether or not pure, (not natural magnesium carbonate)

HS code 251990 covers a range of magnesium oxide products that are produced through specialized high-temperature manufacturing processes. These materials are essential inputs for various industries, including construction, steel production, and chemical manufacturing. As a key component in refractory materials, magnesia products play a crucial role in the global economy, enabling the operation of high-temperature industrial processes.

The production of magnesia products under HS code 251990 typically involves two main techniques: fusion and dead-burning (sintering). In the fusion process, raw magnesium oxide is melted at extremely high temperatures, often exceeding 2,000°C, to create a homogeneous, dense material. Dead-burning, on the other hand, involves heating magnesium oxide to temperatures between 1,600°C and 1,800°C, causing the material to undergo a chemical transformation and become more refractory.

The primary raw material for the production of magnesia products under HS code 251990 is magnesium oxide, which can be derived from natural sources such as magnesite or seawater. In some cases, small quantities of other oxides, such as alumina or silica, may be added to the raw material before the sintering or fusion process to enhance the properties of the final product. Additionally, specialized equipment, including high-temperature furnaces and kilns, is essential for the manufacturing of these materials.

The main outputs of the industry covered by HS code 251990 are various grades of fused and dead-burned magnesia, which are used as refractory materials in a wide range of applications. These products are often consumed by industries such as 272310 Iron and steel industries, 281511 (Sodium hydroxide (caustic soda); sodium oxide), and 282010 Hydrogen peroxide, where they serve as critical components in high-temperature processes and chemical reactions.