"Sintering Activation Process: Essential Criteria for Ignition"

Understanding the Sintering Process: Key Factors Influencing Quality and Efficiency

The process of sintering involves the combustion of fuel within the sinter material to achieve the desired physical properties of the final product. An igniter plays a crucial role by heating the surface layer of the sinter to exceed the ignition point of the fuel, typically around 700 °C. Following this ignition, an exhaust fan facilitates the removal of combustion gases, which is essential for maintaining the ignition process. Additionally, the igniter helps replenish heat in the upper layer of the sintering material, enhancing the overall quality of the sintered ore and reinforcing the sintering process.

One of the critical parameters in sintering is the ignition temperature, which directly impacts both the strength of the surface layer and that of the underlying sintered ore. If the ignition temperature is too low, insufficient heat accumulates in the surface layer, preventing the lower layers from reaching the necessary sintering temperature. Conversely, if the ignition temperature is excessively high, while the strength of the drum may improve, it can lead to over-melting of the surface sinter, resulting in an undesirable increase in FeO content and a decline in reduction performance.

The duration of ignition is influenced by the length of the igniter and the operational speed of the sintering machine. A longer ignition time at a constant temperature allows for greater heat transfer from the igniter to the sinter, which can enhance the strength of the surface sinter and improve overall yield. However, if the ignition time is inadequate, it may be necessary to increase the ignition temperature to ensure that the surface mixture retains sufficient heat.

Historically, there has been a strong focus on enhancing the strength of the surface layer of sintered materials. Techniques such as extending the igniter length and incorporating heat preservation sections were employed to achieve this goal. While these methods can be effective when dealing with thin material layers, the increased height of sintered layers in modern applications has shifted the focus. The specific gravity of the surface layer has decreased, and the inherent strength derived from thicker sintered layers has diminished the emphasis on surface quality.

The oxygen content in the exhaust gases is another significant factor affecting the quality of the sintered ore. Insufficient oxygen can delay the combustion of solid fuels, adversely impacting the strength of the sintered product. The oxygen levels in the exhaust depend on the size and quantity of the solid fuel used, which is critical for maintaining optimal combustion conditions. For instance, a specific mass ratio of the mixture to sinter requires a precise amount of solid fuel to achieve the desired oxygen content for effective ignition.

To enhance combustion efficiency, it is often necessary to increase the amount of oxygen in the exhaust gases by introducing excess air. However, this can be challenging when utilizing a limited supply of coke oven gas in blast furnace operations. Preheating the combustion air or enriching it with oxygen are viable strategies to elevate combustion temperatures and facilitate better heat penetration during the sintering process.

The uniformity of the flame generated during ignition is vital for producing high-quality sinter. Achieving this uniformity requires careful adjustment of burner configurations and the balance of gas and air supplied. Additionally, managing the degree of vacuum during ignition is essential. An excessive vacuum can lead to cold air infiltration, lowering the ignition temperature and causing uneven heating of the material surface. Conversely, insufficient vacuum may prevent the effective removal of combustion products, leading to poor heat utilization.

Moreover, the infiltration of cold air from the sides of the sintering trolley can significantly impact ignition quality. To mitigate this issue, it is important to enhance sealing measures and control the furnace pressure effectively. Many modern sinter plants employ automatic pressure adjustment systems to maintain optimal conditions during the sintering process.

In conclusion, the successful implementation of an efficient ignition process is contingent upon the availability of a well-designed igniter and the careful management of various operational parameters. By optimizing these factors, sinter plants can improve the quality and efficiency of their output, ensuring that the final product meets the required specifications for further processing and use.