Industry knowledge and development
What Is Iron Ore Pellet Pelletizing?
Release on January 08, 2023
Iron ore pelletizing, a crucial step in steel production, utilizes three predominant systems worldwide: the Shaft Furnace system, the Straight Grate system, and the Grate Kiln system. In contemporary times, the Straight Grate and Grate Kiln systems have emerged as the most favored. At CVIC, we pride ourselves on providing comprehensive equipment solutions encompassing all three systems. Our offerings span across mixing, balling, screening, induration, and material handling. By merging the best features of both dominant technologies, our iron ore pelletizing equipment guarantees cutting-edge facilities that produce top-quality pellets at minimized costs.
We cater to pellet plants ranging in capacity from 0.3 MTPA to 9 MTPA
Our expertise extends to engineering, design, and fabricating of principal pelletizing equipment
Iron ore fines, which are smaller fragments of iron ore, undergo a process of agglomeration where they are molded into pellets. Following this, these pellets are subjected to a hardening procedure in a furnace, resulting in robust iron ore pellets. These fortified pellets are commonly introduced into a blast furnace or a Direct Reduced Iron (DRI) plant, playing a pivotal role in the production of steel. Their incorporation ensures the raw material is in an optimal form for the steel-making process, enhancing both efficiency and product quality.
The iron ore pelletizing plants come equipped with an array of equipment designed for specific functions. The primary processes these plants undertake include mixing, balling, screening, indurating, and product handling.
In the mixing stage, the finely ground ore is amalgamated with various binding agents to streamline the following steps. These agents encompass binders such as Bentonite or organic binders, fluxing agents like limestone or dolomite, and for Hematite ore, an internal fuel in the form of coke or anthracite coal is added. This blending is predominantly executed in vertical or horizontal high-intensity mixers, aiming for a homogenous blend of the ore and its additives.
Once the blending is complete, the resulting filter cake progresses to the balling area. In this phase, the ore is agglomerated on pelletizing discs (also known as balling discs) or balling drums, producing green or unfired pellets. The primary objective is to shape the ore into a consistent size, ideally ranging between 9-16mm. Drums, recognized for their high recycle rates, employ a screening circuit to segregate and reroute any off-sized pieces. In contrast, pelletizing discs usually use roller screens to filter out undesired sizes.
As the green pellets move towards the induration process, they undergo a vital screening procedure. Pellets that deviate from the desired size or fines generated during balling or transit are filtered out. These non-conforming pellets are then redirected to the mixer or balling area. Only the pellets that satisfy the size requirements enter the induration machine. Here, irrespective of the use of straight grates or grate kilns, the pellets are initially dried, subsequently heated in a preheat zone to temperatures nearing 800-900°C, and lastly, they complete the induration process at temperatures oscillating between 1200-1350°C.
Following induration, the pellets are cooled to a temperature apt for transport. As these pellets prepare for shipment to load-out facilities, the focus on energy efficiency within these plants becomes evident. The heat emanating from the pellets is cyclically used in the process, fulfilling two objectives: bolstering energy efficiency and reducing fuel use.
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