Uses of magnesium oxide

Animal feed

For a wide range of enzymatic functions of the organism, magnesium is an important element. Therefore, magnesium oxide is often added to mineral feeds with a grain size that should be suitable for the feed mixture and the reactivity is adjusted accordingly. Furthermore, magnesium oxide is an important additive for dairy substitutes and is an effective substance to prevent convulsions in cattle grazing on pastures with low magnesium content.

　　Agriculture

Magnesium as part of the chlorophyll molecule is of great importance for plants. Therefore, magnesium oxide is an essential component of mineral fertilizers. Problems with trees and soil caused by acid rain have also led to the use of magnesium oxide in this field. The low solubility of magnesium oxide and magnesium carbonate allows a longer effective time for acid binding and fertilizer application.

Wastewater treatment

Sewage or wastewater containing ammonia and/or phosphate can be treated in an environmentally friendly way using the MAP process (magnesium ammonium phosphate). By adding magnesium oxide to the effluent, ammonia and phosphate will precipitate due to the insolubility of magnesium ammonium phosphate. Crystalline precipitation is a slow-soluble fertilizer that can be used as a valuable alternative to traditional nitrate fertilizers.

　　Construction Materials

Magnesium oxide cements are used in the production of interior wallboard and fire retardant particleboard. These systems typically contain magnesium oxide, magnesium chloride or magnesium sulfate. A product made from a bituminous clay flooring material called Sorel cement is itself a magnesium chloride cement formed from a solution of magnesium oxide and magnesium chloride.

　　Printing Inks

Used to control the consistency of printing inks.

　　Fire resistant lining

This application consumes the largest amount of magnesium oxide. Magnesium oxide bricks and chrome magnesium bricks are heavy fired magnesium oxide. In the steel industry, kiln linings use large amounts of magnesium oxide in the form of magnesium oxide sinter. Often, foundry tampings and molding sands also contain magnesium oxide. High temperature applications have certain purity requirements for boron content and Ca/Si ratio, so very precise grading is required

　　Corrosion control

Corrosion can be reduced by using magnesium oxide in oil-fired boilers. It works by neutralizing the acid formed by combustion, which usually contains high amounts of sulfur. This application is achieved by blowing magnesium oxide powder into the flame or by adding a magnesium suspension to the fuel oil. Another application is the control of corrosion caused by low melting point vanadium ash (e.g. in turbines). Magnesium oxide reduces corrosion by reacting to form a high melting point vanadium ash.

　　Pharmaceuticals

Magnesium oxide is a component of many antacids, which help bind excess gastric acid produced in the stomach. Vitamin preparations are also often supplemented with magnesium carbonate to compensate for the body\’s magnesium deficiency.

　　Friction lining

Magnesium oxide is used as a coagulant to maintain temperature stability in the manufacturing process of friction brake and clutch linings. Because of magnesium hydroxide in the braking process of heat absorption decomposition properties, so that it can replace some of the functions of asbestos, so there are also used.

　　Grinding wheel

Magnesium oxide can be made into cement (Sorel cement), which becomes an integral part of grinding wheels and grinding stones. Especially for large surfaces and polished (e.g. marble) grinding discs, they are based on magnesium oxide.

　　Surfactants

Various magnesium salts of organic acids are used as surfactants in detergents or as additives to alkaline oils. The source of magnesium in these products is usually magnesium oxide with specific properties.

　　Transformer silicon steel sheets

High performance magnesium oxide with specific reactivity, particle size and flow properties is used to manufacture transformer silicon steel sheets with grain orientation. During the annealing process, the steel is treated with a magnesium oxide coating to form a glass-ceramic film (magnesium olivine). The insulating properties of this film are very important, as is the selection of different magnesium oxide grades.

　　Pulp and Paper

Due to the increasing recognition of the need for energy saving and environmental protection, the magnesium bisulfate method is increasingly used in pulp production. Selected high quality magnesium oxides are used for the production of cooking acid as well as to compensate for the magnesium losses in the recovery process. Among the important quality characteristics are the high proportion of active magnesium oxide and the low silica and lime content. The low iron content is also a decisive factor.

　　Polymers

In many applications magnesium oxide is used for the synthesis of polymers, e.g. for the neutralization and binding of catalyst residual halogens. Magnesium oxide is also used as a buffering agent for thermosetting plastics. Magnesium hydroxide is further used in polymers to impart flame retardant properties. The dehydration that occurs at about 340°C when synthesized and processed at relatively high temperatures can be used for this application. Once a fire starts, it is converted to reactive magnesium oxide, thus limiting smoke production.

　　Fiber Reinforced Polyester Products

In today\’s increasingly popular plastics processing, magnesium oxide and magnesium hydroxide (sometimes) are used to control viscosity in SMC (sheet film plastic) and BMC (agglomerated molding compound) technology. Different qualities of magnesium oxide have different reactivity and we can choose different grades according to the requirements of different applications.

　　Tanning of leather

The chrome tanning process requires a gradual and continuous increase of the pH value during the tanning process. The slow solubility and basic properties of magnesium oxide make it an excellent pH control agent

　　Glass

Magnesium oxide has a long history of use by glass manufacturers. However, special grades of magnesium oxide are essential for modern glass materials with specific optical properties (low IR absorption).

　　Rubber

All chloroprene compounds require highly reactive magnesium oxide in powder form or in convenient paste form to prevent scorching. Basic magnesium carbonate is used as a lightweight filler for rubber compounds, including transparent rubber. The use of magnesium hydroxide as a functional filler in cable insulation and other rubber products can impart flame retardant properties.

　　Ceramics

Porous sintered ceramics prepared with magnesium oxide are used as thermal insulators for current transformers and in the production of \”fusion blocks\”. In the metallurgical industry, crucibles are made of materials containing magnesium oxide. The high density of sintered ceramics containing magnesium oxide stabilizes them during the sintering process and inhibits grain growth.

　　Adhesives and sealants

In chloroprene compounds, magnesium oxide and magnesium carbonate (occasionally) are used as stabilizers. Magnesium oxide prevents the separation of hydrochloric acid from the chloroprene compound and reacts with phenolic resin in this compound to regulate the viscosity. Activity, particle size and environmental properties play a crucial role in the selection of a suitable magnesium oxide quality.