Advantages of Pellets
With the demand of structural adjustment and optimization of China's iron and steel industry, and the requirements of green, low-carbon and high-quality, pellets as high-quality raw materials for blast furnace are more and more favored by the industry, which promotes the rapid development of the pellet industry.
At present, three kinds of pellets are used in blast furnaces at home and abroad, namely acid pellets (R<0.5), fluxed pellets (adding flux) and magnesian pellets (adding magnesium-containing flux). Pellets have the following advantages:
1. The pellet has uniform particle size, high strength and less powder. The porosity is as high as about 30%, the rolling property is good, and the softening temperature is narrower than that of sinter with the same composition, which is conducive to improving the air permeability of the blast furnace slag forming zone, and is conducive to the uniform and reasonable composition of blast furnace material and gas.
2. Pellets have a large specific gravity, which can relatively prolong the residence time in the furnace under the same smelting intensity conditions. Pellets also have small particle size, low FeO content, mainly exist in the form of easily reducible Fe2O3, and have good reduction performance.
3. Pellets contain high iron grade, generally more than 60%, good thermal stability, and stable chemical composition, which is conducive to improving the utilization of gas heat and chemical energy in the blast furnace, promoting the smooth operation of the blast furnace and reducing the coke ratio.
4. Pellets are easy to store, not easy to be weathered and broken in a certain period of time, which is especially suitable for large-scale production and storage of mines.
5. Energy-saving, green and low-carbon
The energy consumption of the pellet production process is about 50% of that of the sintering production process. According to the statistics of the Iron and Steel Association in 2020, the average energy consumption of the sintering process of the member units of the Iron and Steel Association is 48.08kgce/t, and the average energy consumption of the pelletizing process is 24.35kgce/t. Low energy consumption, so the energy consumption of pellet production is low.
Since the heating method of the pelletizing process is different from that of the sintering process, the emissions of SO2, NOX and CO2 formed after combustion are much less than those of the sintering process. In addition, the amount of dust generated by pelletizing is much less than that of sintering, and the pelletizing process is more friendly to the environment. The emission comparison between the sintering process and the pelletizing process is shown in the figure below:
Emission comparison table for sintering process and pelletizing process
Process | SO2（g/t） | NOx（g/t） | CO（kg/t） | CO2（kg/t） | PM emissions（g/t） |
Sintering | 1670 | 640 | 49 | 150 | 260 |
Pelletizing | 200 | 350 | 1 | 100 | 105 |
