Soda Feldspar is a kind of feldspar, which is a common feldspar mineral, namely sodium aluminosilicate (NaAlSi3O8). Albite is generally a glassy crystal, which is colorless or white, yellow, red, green or black. It is the raw material for making glass and ceramics. Albite is found in many rocks, and this mineral is known as a rock-forming mineral. Sodium feldspar is mainly used in the manufacture of ceramics, soap, ceramic tiles, floor tiles, glass, grinding abrasives, etc., and is mainly used for glazes on ceramics.
Albite, a common feldspar mineral, is sodium aluminosilicate (NaAlSi3O8). Most commonly found in pegmatites and felsic igneous rocks such as granite, but also in low-grade metamorphic rocks, and some sedimentary rocks such as authigenic albite. Albite usually forms brittle glassy crystals of various colors. It can be used to make glass and ceramics, but its main significance is that it is a rock-forming mineral. Albite is the sodium terminal mineral of plagioclase solid solution series and alkaline feldspar series. It has a tripod-like structure, with silicon and aluminum tetrahedral coordination forming larger vacancies (i.e., lattice sites), which are mainly occupied by cationic sodium. Although all silicon and aluminum atoms occupy tetrahedral positions in the structure, their exact positions vary. The distribution of silicon and aluminum atoms is highly ordered at low temperatures, but becomes more disordered at high temperatures, around 1100°C.
The chemical formula of albite is: Na2O·Al2O3·6SiO2. Its theoretical chemical composition is Na2O: 11.8%; Al2O3: 19.4%; silicon dioxide: 68.8%. The appearance of albite feldspar is generally white and off-white, with a hardness of 6-6.5, a density of 2.61-2.64 g/cm3, and a melting point of about 1100 °C. The albite mineral in nature is difficult to reach its theoretical value. The closer the chemical composition of feldspar is to its theoretical value, the purer the feldspar and the better the quality. During heating, albite has a theoretical melting point of 1100°C. The melting point of natural albite ore varies with its chemical composition.
Albite has the following characteristics:
1. Quartz, clay, and mullite melt quickly at high temperatures and have high solubility. This
2. Low melting temperature and good transparency. This
3. The melting temperature range is narrower than that of potassium feldspar, the viscosity of the melt at high temperature is smaller, and the change with temperature is faster.
In addition to being used as industrial raw materials, albite minerals account for more than 30% of the ceramic industry, and are also widely used in other industries such as the chemical industry.
1. Glass solvent: feldspar is one of the main components of glass mixture. Feldspar is high in alumina and low in iron content, which can reduce the amount of alkali used. In addition, the process of melting feldspar into glass is relatively slow, and the crystallization ability is small, which can prevent crystals from being precipitated during the glass formation process and damage the product. Feldspar can also be used to adjust the viscosity of glass. Generally, potassium feldspar is used in various glass mixtures. or albite.
2. Composition of ceramic body: Feldspar can be used as a block before firing to reduce drying shrinkage and deformation of the body, improve drying performance, and shorten drying time. It can be used as a flux to fill the green body during firing. Densifying the green body reduces voids and increases the light transmission of the green body.
3. Ceramic glaze: Ceramic glaze is mainly composed of feldspar, quartz and clay raw materials, of which feldspar content can reach more than 15-35%, which is an important component of high-grade ceramic products.
4. Enamel raw materials: Enamel is mainly mixed with mineral raw materials such as feldspar, and the amount of mixing is usually more than 20-30%.
5. Others: Potassium and albite can also be used as high-quality raw materials for the production of chemical fertilizers.
Albite is generally suitable for low temperature ceramics:
1. Before firing, feldspar, like quartz, is a non-plastic raw material, which can shorten the drying time of the green body and reduce drying shrinkage and deformation.
2. Feldspar is the main flux raw material in blank glaze, such as feldspar porcelain, feldspar accounts for about 25% in the blank, and about 50% in the glaze. Its main function is to reduce the firing temperature of the blank. Glaze. This
3. Feldspar is melted at high temperature into feldspar glass, filled between the particles of the green body, and can dissolve other minerals, such as kaolinite, quartz, etc., to make the green body dense, which is conducive to improving the electrical properties and transparency of mechanical strength products .
4. Compared with potassium feldspar, albite has a greater effect of lowering the firing temperature of the glaze, and can increase the light transmittance of the product, but the firing temperature range is not as wide as that of potassium feldspar. This
Requirements for feldspar in ceramic production:
1. The content of K2O and Na2O should be as high as possible, and the content of colored oxides Fe2O3 and TiO2 should be as low as possible;
2. SiO2 content should be in the range of 63%-68%, Al2O3 content should be in the range of 17%-23%;
3. The content of CaO in feldspar should not be too high. If the content is too high, it is easy to lower the sintering temperature when it is used in blanks, and it will affect the fluidity of glazes when it is used in glazes.