Coal Ash Grade
Coal ash is the by-product of burning coal, which is burned in large quantities to generate electricity. The ash is a complex mixture of different materials, including chemicals, minerals and metals. As a result, its quality and composition vary enormously from coal to coal, and even within single deposits. Consequently, coal ash is classified into different grades according to its properties, such as its mineral, particle and metal content.
The primary grade of coal ash used for industrial processes is Class F ash. This ash is low in unburned carbon, but higher in carbon than other ash grades. It also contains a high percentage of calcium, magnesium and alumina as well as silica and iron. The ash is normally of dark gray to light gray color.
The second grade of coal ash is called Class C ash. This ash is low in carbon and is primarily composed of alumina and silica. It is normally white in color, often with a light gray tinge. Class C ash is used extensively in concrete production.
The third grade of coal ash is known as Class G. This ash is low in calcium and high in sulfur. It is normally brown or yellowish in color and is used in steel manufacturing processes.
The fourth grade of coal ash is called Class N ash. This ash is high in silica and sulfur, and contains very little calcium. It is normally very dark in color. Class N ash is commonly used in industrial applications such as grinding, powder coating and as a flux in foundry operations.
Finally, there is a fifth grade of coal ash, known as Class M. This ash is of medium to light gray color and contains a high level of aluminum. It is primarily used in casting operations.
It is important to note that different ash grades can be used in various industrial applications depending on the specific needs of the process. For example, Class F ash may be used in thermal power plants while lower grades, such as Class C and G, may be used in concrete and steel works respectively. As such, coal producers typically analyze the ash produced from their plants in order to determine its grade and select an appropriate application.
To summarize, coal ash is classified into different grades according to its chemical composition and particle size. Class F ash is low in unburned carbon, but high in calcium, magnesium and alumina. Class C ash is low in carbon and composed of silica and alumina. Class G ash is low in calcium, high in sulfur and used in steel manufacturing. Class N ash is high in silica and sulfur and used in industrial applications. Finally, Class M ash is high in aluminum and primarily used in casting operations.
