What are the main production routes for magnesium oxide and their cost implications?

What are the main production routes for magnesium oxide and their cost implications?
Industrial magnesium oxide is made via three dominant routes: thermal decomposition of magnesite or dolomite, seawater extraction, and brine processing after bromine recovery. The magnesite route dominates in China, requiring pre-treatment like heavy-media separation and flotation to remove silica, followed by calcination. Calcination temperature critically determines product activity—450°C yields maximum mesoporosity, while higher temperatures grow crystals and reduce surface area. This directly impacts pricing: light-burned, reactive grades command premiums over dead-burned refractory grades. Producers with captive magnesite mines, such as those in Haicheng, enjoy feedstock cost advantages, while salt lake-based high-purity producers face higher energy and purification costs but sell into premium segments like electronics and pharmaceuticals.