In the ironmaking industry, pelletizing and sintering are two essential processes for transforming iron ore into usable raw materials. Each method has distinct characteristics to meet different blast furnace production needs. So, which process do you primarily use? Do you understand their differences? Are you looking for a more suitable solution? This article will explore the differences between sinter and pellets, the advantages of pellets, and the key factors affecting pellet quality and formation rate, helping you optimize production and improve resource efficiency.

What are Pellets and Sinter?

Pellets are small, round iron ore balls made by mixing iron ore fines with binders. These pellets are indurated through processes like roasting before being used in blast furnaces.

Sinter, on the other hand, is produced by sintering iron ore fines with fluxes, coke, and other additives in a sintering furnace. The final product is in the form of larger, irregularly shaped lumps, which are also used in blast furnace steelmaking.

Differences Between Pellets and Sinter

Raw Material

• Pellets are made by mixing finely ground iron ore with binders like bentonite. The iron ore used is typically of higher quality, with over 85% of the particles smaller than 0.074mm (200 mesh).
• Sinter is produced from iron ore fines, coke, limestone, and other fluxes. Compared to pellets, sinter can use lower-grade iron ore, with particle sizes around 0.8mm.

Production Process Differences

• Pellets are formed by rolling iron ore fines into small balls, which are then hardened through firing in a rotary kiln or grate kiln.
• Sinter is produced by heating iron ore fines at high temperatures, allowing them to fuse into porous lumps through internal combustion in a sintering furnace.

Product Performance Differences

• Pellets offer higher metallurgical strength, better permeability in blast furnaces, and increased productivity.
• Sinter has higher porosity but generally lower mechanical strength than pellets, which can negatively impact smelting efficiency.

Binder

• Pellets use bentonite, organic binders, or composite binders to improve strength and stability during production.
• Sinter relies on fluxes like lime and quicklime to create a liquid phase that bonds ore particles together, enhancing strength.

Environmental Impact

• Sintering requires coke fines as fuel, leading to sulfur dioxide and other pollutant emissions.
• Pelletizing generates fewer emissions, making it a more environmentally friendly process.

Binders in Pelletizing and Sintering

Binders in Pelletizing

During the pelletizing process, various binders are used, including bentonite, organic binders, and composite binders:

• Bentonite: enhances green pellet strength and improves thermal stability.
• Organic binders: provide alternative bonding properties, often reducing impurities.
• Binder selection and dosage impact pellet quality and metallurgical performance, while factors like mixing uniformity also affect production.

Binders in Sintering

In sintering, lime, dolomite, and quicklime act as fluxes:

• Fluxes adjust the sinter’s alkalinity, reducing the need for additional fluxes in blast furnace smelting, thus enhancing furnace efficiency.
• Alkaline substances react with acidic gangue minerals (SiO₂ and Al₂O₃) in iron ore fines to form low-melting compounds, generating a liquid phase that helps bind sinter particles together.

Advantages of Pelletizing Over Sintering

Indeed, sintering and pelletizing have their applications. However, pelletizing offers several advantages over sintering for the following reasons:

1. Higher Productivity: Pellets have better permeability in blast furnaces, improving overall efficiency.

2. Superior Quality: Made from high-grade ore and refined processes, pellets ensure better performance in blast furnaces.

3. Better Reducibility: RI (Reducibility Index) is 70–80% for pellets vs. 65–75% for sinter.

4. Higher Iron Content: 65–67% Fe in pellets vs. 53–58% Fe in sinter.

5. Greater Mechanical Strength: Pellet compressive strength reaches 2500N per pellet.

6. Improved Fuel Efficiency: High mechanical strength helps reduce fuel consumption.

7. Lower Environmental Impact: Higher process efficiency leads to reduced carbon emissions and pollutants.

Summary

Both pelletizing and sintering are crucial processes in the iron-making industry, but pellets often offer superior advantages in terms of product quality and efficiency. With the help of high-quality binders like Jianjie binder for pelletizing, companies can ensure the production of high-performance materials for steelmaking. Jianjie offers custom solutions for binder applications to improve the performance of both pellets and sinter. If you are interested in our service and product, feel free to contact us. We would love to hear from you!