What do refractories include?

According to the product shape, it can be divided into fixed refractories and amorphous refractories, and according to the chemical properties, it can be divided into acid refractories, neutral refractories and basic refractory refractories. The commonly used refractory materials are basic refractory, such as basic magnesia-carbon brick, burnt magnesia brick, magnesia-chrome brick, magnesia-calcium brick, neutral high alumina brick and clay brick. Unshaped refractories include: castable, ramming material, gunning material, daubing material, dry vibrating material, etc. \x0d\x0d\ The raw materials and names of refractories are as follows: \ x0d \ 1. Classification of refractory raw materials \ x0d \ Refractory raw materials can be divided into acidic refractory raw materials according to their chemical characteristics, such as silica and zircon; Neutral refractory raw materials, such as corundum, bauxite (slightly acidic), mullite (slightly acidic), iron ore (slightly alkaline), graphite, etc. Alkaline refractory raw materials, such as magnesium oxide, dolomite sand, magnesia-calcium sand, etc. \x0d\ II。 Classification according to the function of production process \x0d\ According to its function in the production process of refractory materials, refractory raw materials can be divided into main raw materials and auxiliary raw materials. \x0d\ The main raw material is the main body of refractory. Auxiliary raw materials can be divided into adhesives and additives. The role of the binder is to make the refractory blank have sufficient strength in the process of production and use. Commonly used are sulfite pulp waste liquid, asphalt, phenolic resin, aluminate cement, water glass, phosphoric acid, phosphate and sulfate. Some main raw materials themselves have the function of binder, such as bonding clay; The function of additives is to improve the production or construction technology of refractories, or to strengthen some properties of refractories, such as stabilizers, water reducers, inhibitors, plasticizers, foaming agents and dispersants, expansion agents, antioxidants, etc. \x0d\ III。 Classification by acid-base properties \x0d\ According to acid-base properties, refractory raw materials can be mainly divided into the following five categories. \x0d\( 1) Acidic raw materials \x0d\ are mainly siliceous raw materials, such as Yingshi, tridymite, FangShi Ying, chalcedony, flint, opal, quartzite, white silica sand and diatomite. These siliceous raw materials contain at least 90% silicon dioxide (SiO2), and pure raw materials include. Siliceous raw materials are acidic in high temperature chemical kinetics. When metal oxides are present or in contact with them, they react chemically and combine to form meltable silicates. Therefore, if the siliceous raw material contains a small amount of metal oxides, it will seriously affect its heat resistance. \x0d\(2) Semi-acidic raw materials \x0d\ are mainly refractory clay. In the past classification, clay was classified as an acidic raw material, which was actually inappropriate. The acidity of refractory raw materials is mainly free silica, because according to the chemical composition of refractory clay and siliceous raw materials, the free silica in refractory clay is much less than that in siliceous raw materials. Because there is 30%~45% alumina in general refractory clay, and alumina is rarely in free state, it must be combined with silica to form kaolinite (Al2O3 2SiO2 2H2O). Even if there is excessive silica, the amount is very small and the effect is very small. Therefore, the acidity of refractory clay is much weaker than that of siliceous raw materials. Some people think that refractory clay decomposes into free silicic acid and free alumina at high temperature, but this is different. When heating is continued, free silicic acid and free alumina will combine to form dacite (3Al2O3 2SiO2). Inelite has good acid resistance to alkaline slag. At the same time, due to the increase of alumina content in refractory clay, its acidic substances gradually weaken. When alumina reaches 50%, it will have alkaline or neutral properties. Especially the clay brick made under ultra-high pressure has high density, good compactness and low porosity, and its resistance to alkaline slag at high temperature is stronger than that of silica. As far as its erosivity is concerned, Shi Ying is also very slow, so we think it is more appropriate to list refractory clay as semi-acidic raw material. Refractory clay is the most basic and widely used raw material in refractory industry. \x0d\(3) Basic refractory raw materials \x0d\ are mainly magnesite (magnesite), dolomite, lime, olivine, serpentine and high-alumina raw materials (sometimes neutral). These raw materials have strong resistance to alkaline slag, and are mostly used to build alkaline furnaces, but they are particularly easy to react with acidic slag to form salts. \x0d\(4) Neutral raw materials \x0d\ Neutral raw materials are mainly chromite, graphite and silicon carbide (manufactured artificially) and do not react with acidic or alkaline slag at any temperature. At present, there are two kinds of such raw materials in nature, namely chromite and graphite. In addition to natural graphite, there are also artificial graphite. These neutral raw materials have obvious slag resistance, and are most suitable for interlayer of basic refractory and acid refractories. \x0d\(5) Special refractory materials \x0d\ mainly include zirconia, titania, beryllium oxide, cerium oxide, thorium oxide, yttrium oxide, etc. These raw materials have different degrees of resistance to various slags, but due to the lack of raw materials, they can not be widely used in refractory industry, and can only be used under special circumstances, so they are generally called special refractory raw materials.