1. Introduction

Iron ore and iron ore pellets are important sources of iron for manufacturing steel. The iron ore production has significantly expanded in recent years, owing to increasing steel demands in developing countries, such as China and India. However, the content of iron ore in deposits has deteriorated and low-grade iron ore has been processed. The fines resulting from the enrichment by separation after liberation by size reduction must be agglomerated in a pelletizing plant. Consequently, the number of pelletizing plants is expected to increase in the future.

© 2016 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and eproduction in any medium, provided the original work is properly cited. © 2018 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

The quality requirements of pellet, such as physical, chemical and metallurgical specifications, depend on each ironmaking furnace and those requirements influence the operation of the iron ore pelletizing plant.

This chapter aims to provide an overview and the evolution of iron ore pelletizing process

Iron Ore Pelletizing Process: An Overview http://dx.doi.org/10.5772/intechopen.73164 43

The iron ore is mined mostly from open pit deposits through mining operations and the raw product, "run of mine," is subjected to mineral processing. Thus, the material is exposed to a series of operations of fragmentation, separation by size, concentration, dewatering, etc., aiming to adequate the chemical, physical, and metallurgical characteristics to meet the demands of ironmaking processes. The particle size distribution of iron ore is a very important requirement

Materials containing a very fine particle size distribution are not adequate to be used directly in the reduction reactors, requiring to be agglomerated by different processes such as sintering

The main used reduction reactors are the blast furnace (BF) and direct reduction reactors (DR). In the blast furnace, iron is reduced and melted and the most common product is liquid iron called hot metal. In direct reduction, iron remains in solid state and the product is the so-called

Pellets are balls formed by rolling moist concentrates and fines iron ores of different mineralogical and chemical composition, with the addition of additives and binder, in a horizontal

Pellet feed <0.15 Agglomeration by pelletizing to be fed to blast furnace and direct reduction

Generically, the iron ore products for ironmaking can be classified as shown in Table 1.

Lump 6.3–31.7 Directly fed to blast furnace and direct reduction Sinter feed 0.15–6.3 Agglomeration by sintering to be fed in blast furnaces

including:

or pelletizing.

direct reduced iron (DRI).

drum or in an inclined disc [1, 4].

Product Size range (mm) Basic application

Table 1. Iron ore products classification for ironmaking [3].

• Balling technologies • Bonding mechanisms

• Induration technologies

• Pelletizing process and raw materials

• Evolution of binders for iron ore pelletizing

• Challenges and innovations in iron ore pelletizing

2. Pelletizing process and raw materials

to be characterized after its mineral processing.

The idea of rolling moist fine ore in a drum to form balls and then drying and firing it was first patented by A. G. Andersson in Sweden in 1912. Further development was performed to bring the idea to reality. In 1943, E. W. Davies and co-workers demonstrated the process using an experimental shaft furnace. Commercial operation started in the 1950s in Sweden using vertical-shaft-kilns for firing the pellets. Plant capacities were between 10,000 and 60,000 tons/ year [1].

The world installed pelletizing capacity is currently estimated to be 480.7 million tons/year [2]. As shown in Figure 1, China presents the largest production capacity, followed by the United States and Brazil.

The iron ore pelletizing process consists of three main steps:


Figure 1. World installed pelletizing capacity (millions of tons/year). Source: Prepared by the authors with data from Tuck and Virta [2].

This chapter aims to provide an overview and the evolution of iron ore pelletizing process including:


The quality requirements of pellet, such as physical, chemical and metallurgical specifications, depend on each ironmaking furnace and those requirements influence the operation of the iron

The idea of rolling moist fine ore in a drum to form balls and then drying and firing it was first patented by A. G. Andersson in Sweden in 1912. Further development was performed to bring the idea to reality. In 1943, E. W. Davies and co-workers demonstrated the process using an experimental shaft furnace. Commercial operation started in the 1950s in Sweden using vertical-shaft-kilns for firing the pellets. Plant capacities were between 10,000 and 60,000 tons/

The world installed pelletizing capacity is currently estimated to be 480.7 million tons/year [2]. As shown in Figure 1, China presents the largest production capacity, followed by the United

1. Pelletizing feed preparation and mixing: the raw material (iron ore concentrate, additives —anthracite, dolomite—and binders are prepared in terms of particle size and chemical

2. Balling process: the green pellet is the rolled pellet without any thermal process. It is obtained under strict control of moisture and has a spherical shape and diameter of 8–16 mm;

3. Induration process: the green pellets are hardened in a high temperature processing at controlled heating rates, and aiming to achieve the physical and metallurgical require-

Figure 1. World installed pelletizing capacity (millions of tons/year). Source: Prepared by the authors with data from

specifications, dosed, and mixed together to feed the pelletizing process;

The iron ore pelletizing process consists of three main steps:

ments for handling, transportation, and final application.

ore pelletizing plant.

42 Iron Ores and Iron Oxide Materials

year [1].

States and Brazil.

Tuck and Virta [2].

