Refractory Raw Material

Can be divided into oxide raw materials and non-oxide raw materials. With the development of modern science and technology, some organic compounds have become high-performance refractory raw materials precursor materials or auxiliary materials.

According to the chemical properties, refractory raw materials can be divided into acidic refractory raw materials, such as silica, zircon, etc.; neutral refractory raw materials, such as corundum, bauxite (acidic), mullite (acidic), chalcocite (alkaline), graphite, etc.; alkaline refractory raw materials such as magnesia, dolomite sand, magnesia-calcium sand and so on.

According to its role in the refractory production process, refractory raw materials can be divided into the main raw materials and auxiliary raw materials。

The main raw material is the main body of the refractory material. Auxiliary raw materials can be further divided into binding agents and additives. The role of the binding agent is to make the refractory billet has enough strength in the production and use process. Commonly used sulfite pulp waste, asphalt, phenolic resin, aluminate cement, water glass, phosphoric acid and phosphate, sulfate, etc., some of the main raw materials themselves have the role of binding agent, such as combining clay; additives to improve the production of refractory materials or construction process, or to strengthen some of the properties of the refractory material, such as stabilizers, water reducers, inhibitors, plasticizers, foaming agent dispersant, expansion agent, Antioxidant, etc.

According to the acidity and alkalinity, refractory raw materials can be mainly divided into the following five categories.

Mainly siliceous raw materials, such as: quartz, scale quartz, quartz, chalcedony, flint, opal, quartzite, white silica sand, diatomaceous earth, these siliceous raw materials contain at least 90% of silicon oxide (SiO2), pure raw materials have up to 99% of silicon oxide. Silica raw materials in the high temperature chemical dynamics is acidic in nature, when there is a metal oxide, or its contact with the presence of chemical reactions, and combined into a fusible silicate class. Therefore, if the siliceous material contains a small amount of metal oxides, it seriously affects its heat resistance.

Mainly refractory clays. Clay has been categorized as an acidic raw material in the past, but this is not appropriate. The acidic basis of refractory raw materials is based on free silica (SiO2) as the main body, because according to the chemical composition of refractory clay and siliceous raw materials, refractory clay free silica is much less than siliceous raw materials. Because in general refractory clay in 30% ~ 45% of the alumina, and alumina is rarely free state, must be combined with silica into kaolinite (AI2032SiO2-2H20), even if there is excess silica amount is also very small, the role is also very small. Therefore, the acidic nature of refractory clay is much weaker than siliceous raw materials, some people believe that the refractory clay decomposition at high temperatures to become free silicic acid, free alumina, but it is not the same in this case, in the continued heating of free silicic acid and free alumina will be combined with the Yinglai stone (3A203-2SI02), Yinglai stone on the alkaline slag has a very good resistance to acid performance, at the same time, due to the alumina component of refractory clay, its acidic properties. At the same time, due to the alumina content in the refractory clay, its acidity gradually weakened, when the alumina reaches 50%, there will be alkaline or neutral nature, especially in the ultra-high pressure made of clay bricks, high density, detailed and compact, low porosity, resistance to alkaline slag under high temperature conditions than silica is stronger. In terms of its erosive properties, Yinglai stone is also very slow, so we believe that the refractory clay is classified as semi-acidic raw materials is more appropriate. Refractory clay is the most basic and widely used raw material in the refractory industry.

Neutral raw materials, mainly chromite, graphite and silicon carbide (manufactured artificially), do not react chemically with acidic or alkaline slag at any temperature. At present, there are two such materials in nature, namely, chromite and graphite. Graphite in addition to natural, there are man-made graphite, these neutral raw materials, slag have significant resistance properties, the most suitable for alkaline refractory materials and acid refractory materials used as a compartment.

Mainly magnesite (rhodochrosite), dolomite, lime, olivine, serpentine, high-alumina oxygen raw materials (sometimes neutral), these raw materials have a strong resistance to alkaline slag, mostly used in the masonry of alkaline furnaces, but especially prone to acidic slag and the chemical reaction and become salts.

Mainly zirconium oxide, titanium oxide, beryllium oxide, cerium oxide, thorium oxide, yttrium oxide and so on. These raw materials have different degrees of resistance to various slag, but due to the source of raw materials are not many, can not be applied in large quantities in the refractory industry, can only be used in special circumstances, so commonly known as special refractory raw materials.

9 Common Mistakes to Avoid When Choosing Refractory Raw Materials

Lack of understanding
One of the biggest mistakes is not fully understanding the specific requirements of the application. Before selecting a refractory material, it is essential to thoroughly evaluate factors such as temperature range, chemical exposure, thermal cycling, and mechanical loads.

Neglecting material properties
Each refractory has unique properties that make it suitable for specific applications. Ignoring these characteristics and choosing a generic or one-size-fits-all approach can lead to premature failure and poor performance.

Overlooking thermal conductivity
Thermal conductivity is an important property that affects heat transfer efficiency. Failure to consider the required thermal conductivity can lead to energy losses and poor temperature control.

Neglecting corrosion resistance
Industrial environments often involve exposure to corrosive gases, liquids, and solids. Failure to select a refractory with adequate corrosion resistance can lead to chemical reactions, material degradation, and reduced service life.

Improper installation considerations
Refractories require proper installation techniques and expertise. Ignoring installation considerations such as cure time, drying procedures, and thermal expansion joints can compromise the integrity and performance of the refractory lining.

Underestimation of thermal expansion
Refractories experience thermal expansion and contraction. If these dimensional changes are not taken into account, the lining may crack, flake, or fall off.

Neglecting mechanical loads
Industrial processes often impose mechanical stresses from equipment and materials. Ignoring these loads and their effects on refractories can lead to premature failure and reduced performance.

Neglecting wear resistance
In some applications, abrasive materials and high velocity flows are used. Neglecting the wear resistance of refractories can lead to erosion, wear, and loss of lining thickness.

Cost-driven decisions
Cost is an important factor, but selecting materials based solely on upfront cost without considering long-term performance, maintenance, and downtime costs can be a costly mistake. There is a possibility.