Mica (Mica) is a general term for layered structure aluminosilicates such as potassium, aluminum, magnesium, iron, lithium, etc. It is generally polymorphic and has a layered structure, not a crystal. It is not easy to determine its melting point, but it is generally in the Around 1800℃ or even higher. Synthetic mica powder

Mica is usually in the form of false hexagonal or rhombic plate, flake, and columnar crystal. The color varies with the change of chemical composition, and mainly becomes darker with the increase of Fe content. Muscovite is colorless, transparent or light-colored, and biotite is black. To dark brown, dark green and other colors, phlogopite is yellow, brown, green or colorless, lepidolite is lavender, rose red to gray, vitreous luster, pearl luster on cleavage surface, Mohs hardness is generally 2 ~ 3.5 , the specific gravity is 2.7~3.5, the cleavage of the parallel bottom surface is very complete, muscovite and phlogopite have good electrical insulation and non-thermal conductivity, acid resistance, alkali resistance and pressure resistance, so they are widely used in the production of electronic and electrical industries. Insulating materials, mica fragments and powders are used as fillers, etc. Lepidolite is also the main mineral raw material for lithium extraction.

Using mica ore as raw material Lingshou mica powder to produce mica powder, there are two current methods: dry method and wet method. The grade of mica ore is generally low 20% to 40%, and dry production does not have ore washing, and the original ore is removed by hand. The stones that are visible to the naked eye are directly ground by dry method, so the mica content of dry mica powder depends on the grade of the ore, and the purity varies greatly (30%-50%). It is impossible to obtain high-purity mica powder. Most of them are stone powders (powders of quartz, feldspar, strong soil, etc.) rather than mica powder. Elemental analysis shows that the content of SiO2 is surprisingly high (about 70%), while K2O is very low (3-5%) or not (with Talc powder, kaolin counterfeit mica powder), if such mica powder is used to prepare coatings, the quality of coatings will fluctuate greatly, especially when dry production uses powerful grinding machines such as Raymond mills. During grinding, even quartz Extremely hard substances such as sand are ground into micron-sized powders, so the mica shape is severely damaged.

Even if a wafer is formed, the wafer is much more fragile than the particle, so the mica powder manufacturer is repeatedly broken, the micro-particle-to-thickness ratio is very low (about 10 times), the thickness is micron rather than nanoscale, and the wafer is often torn. , perforation and surface grinding and other defects, this inferior product is used in foreign countries to make cattle felt, electric welding rod, drilling mud, etc., and is generally not used as functional filler. Furthermore, because there is no ore washing, iron, chromium in the product The content of other elements is high, which catalyzes the aging of the paint film and reduces the insulation level of the insulating paint. Since 1 ton of raw ore can produce 800-900kg products, and the production method is very simple, the production cost of dry mica powder is very low, and the mesh, Crystalline damage caused by dry grinding is absolutely irreparable, although dry grinding can also be done very fine (eg 1250 mesh), but the particle size distribution is usually very broad (eg <1 to 160 microns almost evenly distributed).

After dry grinding, elutriation is used to separate out part of the stone powder, and the mica content can also be increased. However, it is extremely difficult for micron-level powder to remove impurities by elutriation. The effect is very low, and the purity can only be increased by 10% to 20%. "Wet product" or "semi-dry and semi-wet product".