Thermal decomposition of magnesite or dolomite generates magnesium oxide. Magnesium hydroxide precipitate is obtained first by treating seawater with hydrated lime; magnesium oxide is obtained by burning magnesium hydroxide. Alternatively, we can take the magnesium chloride lumps or brine after bromination as raw material during the comprehensive utilization of seawater; add sodium hydroxide or sodium carbonate to generate magnesium hydroxide or basic magnesium carbonate precipitation, and then burn to obtain magnesium oxide. At present, China mainly uses magnesite, dolomite, brine or halogen as raw material.
Magnesium oxide accounts for the largest amount of magnesium compounds, accounting for about 3/4 of the total magnesium industry. Magnesia made at temperatures below 900 ° C is light magnesia with low density, having large specific surface area and strong absorbability. Can be used as a catalyst, rubber filler and improve the performance of rubber accelerator. Mixing with magnesium chloride solution can make magnesia cement. It can also be used as flame retardant for building materials. It can be medically used as antacids and laxatives for the treatment of hyperacidity and stomach and duodenal ulcer disease, often combined with calcium carbonate easy to cause constipation. For animal feed additives and plant fertilizers. The light magnesium oxide obtained at 950 ~ 1050 ℃has high density with particle distribution having a certain range and being easier to hydrate.
Use it to react with the silica on the silicon steel surface at high temperature to produce magnesium silicate film-like product; it can be used as a silicon steel separator to prevent the sintering of silicon steel upon high-temperature sintering. The heavy magnesium oxide prepared at high temperature of 1500-1800 ℃ has high density, small specific surface area, be difficult to be decomposed by heat, has low chemical activity, not easily to react with acid and low hydration rate. It can be used as high temperature refractory materials and the binder during manufacturing refractory crucible and the furnace lining.