Introduction
Permeability index is an essential parameter used in assessing the quality of blast furnace sinter. A high permeability index indicates good permeability of the sinter, good thermal insulation and thermal conductivity, good refractoriness, and low porosity. Blast furnace permeability has been a subject of research in the iron and steel industry for many years. Permeability can be defined as a measure of the rate of passage of gases through a body or surface. The use of permeability as a measure of sinter quality has been recognized for a long time, since it plays an important role in the efficient operation of the blast furnace. The quality of the sinter depends on its permeability, structure and chemical composition, as well as its ability to withstand thermal shock and corrosion.
2. Properties of Blast Furnace Permeability
Blast furnace permeability is the quality of a sinter that affects its ability to be permeable to gases. It describes how quickly gases can move through the sinter material. Gases in blast furnaces can be air, carbon dioxide, and other elements found in the material that keeps the blast furnace running. Having a higher permeability of sinter is beneficial as it allows efficient transfer of heat, energy and gases between the lower and upper parts of the blast furnace, allowing the furnace to operate at maximum efficiency. Additionally, permeability of sinter affects the longevity of the blast furnace as gas permeability is essential to preventing corrosion of the furnace walls.
3. Causes of Poor Blast Furnace Permeability
There are several factors that can affect the permeability of a sinter. The most common causes of poor permeability are: a high ash content of sinter, high amounts of fines or dust, overcharging of the charge composition, too much or insufficient material, or incorrect material selection. Additionally, high levels of sintering time and temperature can reduce the permeability of the sinter. Over time, poor permeability can accumulate due to the sinter structure becoming more structured, acting as a barrier to gas passage.
4. Methods of Improving Blast Furnace Permeability
There are several methods of improving blast furnace permeability indexes. The first is to improve the homogeneity of the sinter mix. This can be done by reducing the amount of fines and dust in the mix, and controlling the grain size of the fired sinter so that it is homogenous and free of large particles. Additionally, the charge mix should be adjusted to the optimal sinter mix, and the sintering temperature and time should be adjusted to allow the maximum gas passage.
Another method of improving permeability is by reducing the sinter porosity. This can be achieved by reducing the ash content of the sinter, as well as using additional binders or additives to reduce porosity and improve the overall structure of the sinter. Additionally, pre-treatments such as pre-wetting or pre-oxidation can help to reduce porosity. Finally, the use of high quality refractory material can increase the permeability of a sinter and ensure a better overall performance.
5. Conclusion
In conclusion, blast furnace permeability is an essential parameter used in assessing the quality of sinter. Improving the permeability of a sinter can have numerous benefits, including increased thermal efficiency and corrosion resistance, as well as longer lasting blast furnaces. There are several methods of improving permeability, such as improving the homogeneity of the sinter mix, reducing the sinter porosity, and using high quality refractory material.
