Kalpesh Meghani

Silica and alumina affect the granulation of iron ore favorably if the technological process is done correctly. It is necessary that the corresponding hydroxides cover the particles of iron ore with a thin layer, and then under the influence of temperature turn back into polymerized oxides. The creation of this process is the art of the experimenter. Perhaps the following article will help you on the way to implementing this technology.

Article Chemistry for Sustainable Development 20 (2012) 315–322 Iron...

Dear Kalpesh Meghani

Here I have been trying to give the answers....

1. How does silica content affect pelletization?

High silica content reduces the iron grade of pellets and increases slag volume during ironmaking, requiring more flux and energy. It may weaken pellet strength if it interferes with bonding, though small amounts can help form slag-bonding phases when fluxes are added.

2. How does alumina content affect pelletization?

High alumina increases slag viscosity, making slag handling more difficult and reducing furnace efficiency. It also lowers pellet strength and reducibility by forming viscous phases that trap gases and hinder reduction reactions.

3. How does the combination of silica and alumina affect pelletization and pellet quality?

When both are high, they further reduce pellet quality, leading to poor strength, lower reducibility, and increased slag formation. This demands more flux and energy, reduces furnace productivity, and raises operational costs. A balanced SiO₂/Al₂O₃ ratio and controlled basicity are essential to maintain good pellet performance.

What shall be the Optimum and maximum amount (%) of SiO₂/Al₂O₃ in pellet? impact on porosity?

Kalpesh Meghani

With an increase in the basicity of pellets made from concentrates containing 7-10% SiO2, the open porosity increases. If the volume fraction of total and open pores in unfluxed pellets is 18% and 14%, respectively, then in pellets with a basicity of 0.5 it is 24% and 15%, and in pellets with a basicity of 1.2 it is 37% and 34%. This is explained by the fact that with an increase in the amount of limestone in the charge at the stage of solid-phase sintering, dissociation of carbonates occurs. As a result, the structure of the pellets loosens, and an increase in the amount of melt at the stage of liquid-phase sintering leads to coalescence of pores and an increase in their volume. (Zhuravlev F.M., 1991)

https://metalspace.ru/production-science/technology/iron-ore-rawmaterials/701-proizvodstvennye-moshchnosti-i-okatyshi-rf.html