**1. Introduction**

#### **1.1. Importance of the steel and iron industry**

The iron and steel industry produces products with desired chemical and physical properties from the melting iron ore in blast furnaces or the melting scrap in arc furnaces by different processes [1]. Changing consumer needs, developments in technology and competition are further increasing the product diversity in the iron and steel sector. Final steel products have numerous types and different application areas. The iron and steel industry, which is the most

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important of the heavy industry sectors, supplies raw materials to many important industries such as construction, infrastructure, automotive, white goods and machinery industry. Therefore, it can be said that industrialization of a country is directly related to its strong iron and steel sector and consumption [2]. **Table 1** gives the top 10 countries producing the crude steel in the world.

Today iron constitutes the basic raw material of the industry and plays an important role in the economic development of the countries. The economic development indicators of countries are also determined by per capita iron and steel consumption. **Table 2** shows the consumption of steel per capita.

In the past, iron ore with the characteristics required for blast furnace charging was met directly from iron mines. The need for iron in the industry has increased rapidly and also the reserve of the iron ore which can be directly loaded into the blast furnace has gradually decreased. Therefore recently, the irons ores with low grade have been started to be evaluated. The crude iron ore reserves and its iron content in the world are given in **Table 3**.

The main raw material of the iron and steel industry is iron ore. It must be economical to operate and use a mine as an ore. It is desirable that the blend grade of the iron ores used in the steel industry is at least 57% Fe grade. The iron ore is found in the form of magnetite (Fe3 O4 ), hematite (Fe<sup>2</sup> O3 ), limonite (FeO(OH)⋅nH<sup>2</sup> O), goethite (α-Fe3+O(OH)), siderite (FeCO3 ) and pyrite (FeS<sup>2</sup> ) minerals in the nature.
