Brucite is produced by the hydrolysis of soluble magnesium-containing compounds in a strong alkaline solution. It is a secondary change product of an alkaline solution acting on a magnesium silicate. The deposit is mainly related to serpentine; it is also produced in contact with metamorphic magnesite limestone, and it is symbiotic with calcite, tremolite, serpentine, and phlogopite. It is sometimes produced in dolomite chemical limestone and is associated with calcite, hydromagnesite, and periclase. Brucite ore can be divided into three main types: spherical type, block type and fiber type:
Spherical type: hydrated from periclase, producing nodules, with a diameter from several millimeters to more than 20cm. The nodules are cemented by cryptocrystalline brucite and a small amount of calcite and serpentine. The ore is of good quality.
Block type: Hydrothermal alteration products of magnesia-rich rocks. The ore is a crystalline and granular aggregate, coexisting with serpentine, calcite, magnesite, etc., with a brucite content of about 30-40%.
Fibrous type: It is produced in serpentine in veins, and the content of wollastonite is generally 1-9%. The rock minerals are serpentine and magnetite. Wollastonite has high purity.
Brucite is widely used in fire protection coatings, paper industry, magnesium oxide production, magnesium chloride production, brucite powder, environmental protection and other fields.
(1) Fireproof coating
Brucite has a particularly high water content, about 31%. The differential thermal analysis of brucite shows that its thermal decomposition and dehydration temperature is between 420 and 520 ° C, which is close to the burning temperature of general goods, so it can be used as a fireproof coating and flame retardant. Japanese scholars have developed a coating which is a mixture of hydraulic cement, slightly treated brucite and some other substances in an appropriate ratio. This coating has the characteristics of light bulk density, good decoration, strong weathering resistance, good fire resistance, and does not peel off after fire. Can be used for surface coating of ships, high-end houses, etc.
2) Paper industry
Brucite has the characteristics of high whiteness, good exfoliation, strong adhesion, and basically does not absorb water. The former Soviet Union used it with calcite as a filler for papermaking, changing the papermaking method from acid method to alkaline method, and reducing pulp pollution . In the paper industry, brucite replaces lime in the production of magnesium-based sulfite pulp, which can absorb and reuse waste pulp water, which greatly reduces the environmental pollution of waste pulp water. Because brucite does not absorb water in the air, it can also be used as a filler for moisture-proof packaging paper.
(3) Preparation of magnesium oxide
In brucite, the magnesia content is high, and the brucite can be directly calcined to obtain magnesia, and the process is simple, the cost is low, and it is easy to control. Refractory magnesia can be produced by using brucite. Brucite has been greatly developed as a refractory in foreign countries. Abroad, brucite and dolomite are calcined into magnesium and calcium oxides at high temperatures, then ground, mixed with organic binders, pressed into molds, and then fired to produce refractory brick products. High-grade magnesia was obtained. Brucite has been greatly developed abroad as a refractory material. Japan needs to import about 40,000 to 50,000 t of brucite every year to meet the needs of industrial development.