Effect of Iron Ore Pellet Size on Metallurgical Properties

Mikko Iljana,Timo Fabritius,Olli Mattila,Timo Paananen,Mikhail Kondrakov

doi:10.3390/met12020302

Mikko Iljana, Timo Fabritius + Show 3 more

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https://doi.org/10.3390/met12020302

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Abstract

Iron ore pellets are small and hard spherical particles agglomerated from a fine iron ore concentrate. They are used in the blast furnace process to produce hot metal. The diameter of blast furnace pellets is usually between 8 and 16 mm. In this study, a batch of magnesia iron ore pellets was first sieved into particle sizes of 8–10 mm, 10–12.7 mm, 12.7–16 mm and 16–20 mm, and the four different size fractions were used to study the effect of pellet size on metallurgical properties. The metallurgical experiments showed a decrease both in reducibility under unconstrained conditions and in low-temperature reduction-disintegration but showed an increase in cold crushing strength as the pellet size increased. In the reduction-softening test, pellets sized 10–12.7 mm reached the highest final temperature and the highest reduction degree among the pellet samples of different sizes. Based on the implications drawn from this study, the amount of 10–12.7 mm pellets should be maximized in a blast furnace operation.

Highlights

Iron and steelmaking is one of the most energy-intensive industrial sectors
Divalent iron content slightly increased in the pellets as the pellet size increased
The results obtained in this study are summarised as follows: 1. Reducibility under unconstrained conditions decreased as pellet size increased

Summary

Introduction

Iron and steelmaking is one of the most energy-intensive industrial sectors. The dominant process for making iron worldwide involves a blast furnace (BF), which has a long-lasting history. Iron ore pellets are small and hard spherical particles agglomerated from a fine iron ore concentrate They are hardened at high temperatures to attain sufficient mechanical strength. Fired pellets are durable and easy to handle, and they perform well in blast furnaces, with good permeability and reducibility [2]. Their diameter is usually 8–16 mm [3]. Pellets can be divided into acid (B2 < 0.5) and basic (0.9 < B2 < 1.3) type Some additives, such as limestone (CaCO3), dolomite (CaMg(CO3)2) or olivine (Mg2SiO4), are usually used to produce high-quality pellets with good reducibility and superior softening and melting properties. Bentonite, which is a clay mineral containing silicates, is often used as a binder for making iron ore green pellets [4,5]

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