Original Article

The properties of pellets produced with high-silica iron ore concentrate by optimizing the fluxes

JSW Steel Limited Bellary, Kaenataka, India

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Received: 10 March 2026
Accepted: 22 June 2026

Abstract

Rising pellet production and declining high-grade ore availability are making high-silica concentrates a necessary alternative to meet industry demands. However, the use of high-silica iron ore concentrate in the pelletization process adversely affects the pellet properties and increases the blast furnace slag rate. This study investigated the effect of silica content from 3% to 11% on pellet cold compressive strength (CCS), reduction degradation index (RDI), and reducibility index (RI). Furthermore, with higher MgO addition and modified pellet basicity, the properties of the high-silica pellets improved. The mineralogical phases formed during the induration process greatly affect the pellet properties. Microstructural investigations were conducted using an optical microscope paired with an image analyzer to understand phase formation and its influence on pellet properties. The compressive strength of the pellet increased from 261 to 305 kg/p with up to 7% silica initially. A further increase in silica decreased the pellet strength. The CCS of the pellet with 9% and 11% silica was 275 and 248 kg/p, respectively. The reduction degradation index (–6.3 mm) decreased from 9.65 to 3.88%, and the reducibility index of the pellet decreased from 78.8 to 73%. At 11% silica, 0.9% MgO, and a basicity of 0.5, the pellet's CCS was 264 kg/p, RDI (–6.3 mm) 3.88%, and RI 75%. The changes in pellet strength, RDI, and RI were due to an increase in the slag phase, a decrease in the silicate, and the pore phase.