Application fields and quality requirements

Flame retardant refers to an additive that can make the polymer not easy to catch fire and slow down its combustion after it catches fire. Inorganic flame retardants, such as aluminum hydroxide and magnesium hydroxide, rely on chemical decomposition to absorb heat and release water, and have the characteristics of non-toxicity, smoke suppression and stable chemical properties of decomposition products (aluminum oxide and magnesium oxide), so they do not cause secondary hazards. The flame retardant filler prepared from brucite has dual functions of filling and flame retardant, and has the following characteristics: 1) It is halogen-free and belongs to non-halogen flame retardant; 2) The processing temperature is high (the initial decomposition temperature is much higher than that of aluminum hydroxide, up to 320℃, and that of aluminum hydroxide is 220℃), so it can be applied to resins with higher processing temperature; 3) It is non-toxic and tasteless, does not produce toxic gas during combustion, does not corrode the mold, does not produce secondary pollution, and has excellent flame retardant and smoke suppression performance. However, the use of magnesium hydroxide as flame retardant has the following disadvantages: First, the flame retardant efficiency is relatively low, which requires a higher amount of addition; Second, its surface is naturally "hydrophilic and oleophobic", which is difficult to disperse evenly in organic polymers. High-grade magnesium hydroxide flame retardant can be prepared by ultrafine grinding and proper surface modification of brucite ore. China has not specified the relevant quality standards for flame retardants prepared from brucite. Table 1 shows the main technical parameters of Zerogen series products prepared and synthesized from brucite by Huber Company of America. The main component of brucite is magnesium hydroxide, which is decomposed into magnesium oxide after being crushed and calcined. Using brucite to produce magnesium oxide has the advantages of saving energy, reducing pollution and low cost. Products can be used in the fields of refractory materials and building materials. The production of light burned magnesium and heavy burned magnesium is currently the main use of brucite ore in China. Using brucite to produce magnesium is also one of its application fields. It is the same as producing magnesia with brucite, and has the advantages of environmental protection, low energy consumption and low cost. Reinforcing and reinforcing fiber Because fibrous brucite is hard and easy to disperse in slurry, acicular fiber bundles are easy to loosen after being soaked in water, not easy to clump, and have larger volume expansion than other fibers after being loosened, so it is an excellent reinforcing and reinforcing material. At present, fibrous brucite is mainly used in producing middle-grade thermal insulation materials such as microporous calcium silicate and calcium silicate board. It is characterized by high whiteness, small volume weight and low cost, and can replace asbestos fiber to manufacture asbestos-free thermal insulation materials. fireproofing By calcining brucite at high temperature, light burned magnesia and heavy burned magnesia (brucite bitter soil) can be prepared. If lithium hydride or lithium fluoride is further added, it is pressed into pellets with a diameter of 40-60 mm, then put into smelting, and magnesium agent and rare earth catalyst are added in the smelting process, so that high-purity magnesia can be obtained. Calcined brucite and dolomite into magnesium and calcium oxides at high temperature, then ground, mixed with organic binder, pressed into a mold, and calcined twice to obtain refractory bricks. This refractory brick can be used in metallurgical industry instead of magnesia refractory brick. Other fields Brucite can also be used as a protective layer for nuclear reactors in nuclear power plants. Magnesia flux and electrode coating; Heat insulation material; Combustion corrosion inhibitors and handicrafts, etc. In recent years, some researchers have used brucite powder as neutralizer for acidic wastewater. Compared with lime, magnesium hydroxide is safer and more efficient because it is less alkaline than calcium hydroxide and will not cause harm to human body. However, its price is more expensive than lime and its application is limited. Other researchers use brucite to make magnesium hydroxide slurry for flue gas desulfurization.