*1.1.2 The influence of the properties of iron ores and concentrates on the final quality of the sinter and on the production of pig iron*

The operation of the blast furnace and the results of its work are most often evaluated according to the output and consumption of coke. Changes in the chemical composition and particle size distribution of the iron-bearing materials significantly affect their technological properties and thus the balance of components and the course of the blast furnace process. The development of iron metallurgy is conditioned by the quantity and quality of iron ores. The raw material base for iron production is characterized:


To meet the requirements of the metallurgical industry, mined ores are increasingly treated and processed before being used in blast furnaces, and the treatment of ores must ensure:

• an increase in the iron content and removal of harmful and unwanted impurities,


A good quality sinter is characterized by a suitable iron content, high reducibility, good strength and low fine grain shares content prior to charging into blast furnace and high strength after reduction in the blast furnace shaft. The influence of the properties of iron ores and concentrates on the final quality of the sinter is specified on **Figure 7**. **Figure 7** shows very good mechanical (strength) and metallurgical (reducibility) properties of major oxides (hematite and magnetite) and calcium ferrites. On the other hand, silicates have unfavorable properties. The sintering product should have the proper physical features to bear transporting and should not produce dust while in the blast furnace. The sinter should be of good chemical, mineralogical and metallurgical properties and should contain as few detrimental admixtures as possible. In **Table 9**, some important properties of industrially produced sinters are listed, while the critical requirement

**Property of Fe sinter SI unit Min Max** Content of Fe TOT [%] 48.20 57.00 Content of FeO [%] 8.70 19.80 Content of CaO [%] 7.30 14.40 Content of SiO2 [%] 5.40 9.60 Content of P [%] 0.02 0.04 Content of S [%] 0.03 0.05 Content of Na2O+K2O [%] 0.05 0.08 Basicity [] 1.15 2.10 Granulometry [mm] 5.00 50.00 Porosity [%] 27.00 38.00

**1.2 Modeling and simulation of sinter production under laboratory conditions**

Reducibility (ISO 7992) [%] 60.00 85.00 Reducibility (ISO 4695) [%/min] 0.80 1.40 Drum strength +6.3 mm [%] 65.00 78.00 Abrasion index 0.5 mm [%] 4.20 9.80

] 4.13 4.44

The course of processes in the sintered material can be evaluated on the basis of changes in the physical and metallurgical properties of the sintering product. The transformation of the components of a material is related to the decrease in Gibbs free energy. It is possible to calculate the maximum work of reactions, i.e. oxidation reactions, reaction in solid state, reactions during formation of a melt and also reactions taking place during the recrystallization and cooling down of sintering

Thermodynamic calculations are thus essential when determining the characteristics of a technological process and they enable one to clarify the formation of

*1.2.1 Material-heat balance and thermodynamic study of sinter production*

products.

**65**

**Table 9.**

*Properties of Fe sinters [10].*

for all sinter properties is stability [10].

*Advances in Sintering of Iron Ores and Concentrates DOI: http://dx.doi.org/10.5772/intechopen.94051*

Real density [g.cm<sup>3</sup>

The implementation of the above requirements will achieve good permeability of the burden column, reduction of the amount of slag-forming additives in the burden, reduction of specific coke consumption, increase of blast furnace output, improvement of pig iron quality, more even operation of the furnace without more serious failures and fluctuations, reduction of iron production costs. In the blast furnace process, zinc and lead from iron raw materials belong among the so-called harmful elements with a significant influence on the formation and growth of sediments [5–7]. Potassium and sodium are undesirable in the blast furnace charge due to the disruption of the integrity of the carbon and graphite linings [5, 7].

The requirements for the quality of sinter are constantly increasing. The chemical and mineralogical composition of sintered materials affects the wettability of their surfaces and also influences considerably the strength of the binding of the material grains in the green pellets, and in this way also influences the conditions of sintering. The sintering rate depends on the initial properties of the iron ores and concentrates and the heating conditions of the sintered materials, i.e. it depends on the geometric parameters of ores and concentrates (grain size composition, the size of specific surface, grain morphology, microgeometry of the surface, porosity) and on the structural activity of the material.

#### **Figure 7.**

*The influence of various factors on the Fe sinter (modified by authors according [2]). SFCA = silicoferrites of calcium and aluminum, strength and reducibility were realized on pure mineral compounds.*

### *Advances in Sintering of Iron Ores and Concentrates DOI: http://dx.doi.org/10.5772/intechopen.94051*

• improving the physical and mechanical properties of ores,

• averaging and stability of chemical composition and lumpiness of iron ore raw

The implementation of the above requirements will achieve good permeability of the burden column, reduction of the amount of slag-forming additives in the burden, reduction of specific coke consumption, increase of blast furnace output, improvement of pig iron quality, more even operation of the furnace without more serious failures and fluctuations, reduction of iron production costs. In the blast furnace process, zinc and lead from iron raw materials belong among the so-called harmful elements with a significant influence on the formation and growth of sediments [5–7]. Potassium and sodium are undesirable in the blast furnace charge due to the disruption of the integrity of the carbon and graphite linings [5, 7].

The requirements for the quality of sinter are constantly increasing. The chemical and mineralogical composition of sintered materials affects the wettability of their surfaces and also influences considerably the strength of the binding of the material grains in the green pellets, and in this way also influences the conditions of sintering. The sintering rate depends on the initial properties of the iron ores and concentrates and the heating conditions of the sintered materials, i.e. it depends on the geometric parameters of ores and concentrates (grain size composition, the size of specific surface, grain morphology, microgeometry of the surface, porosity) and

*The influence of various factors on the Fe sinter (modified by authors according [2]). SFCA = silicoferrites of*

*calcium and aluminum, strength and reducibility were realized on pure mineral compounds.*

• improving the reducibility of individual types of ores,

materials.

*Iron Ores*

**Figure 7.**

**64**

on the structural activity of the material.

A good quality sinter is characterized by a suitable iron content, high reducibility, good strength and low fine grain shares content prior to charging into blast furnace and high strength after reduction in the blast furnace shaft. The influence of the properties of iron ores and concentrates on the final quality of the sinter is specified on **Figure 7**. **Figure 7** shows very good mechanical (strength) and metallurgical (reducibility) properties of major oxides (hematite and magnetite) and calcium ferrites. On the other hand, silicates have unfavorable properties.

The sintering product should have the proper physical features to bear transporting and should not produce dust while in the blast furnace. The sinter should be of good chemical, mineralogical and metallurgical properties and should contain as few detrimental admixtures as possible. In **Table 9**, some important properties of industrially produced sinters are listed, while the critical requirement for all sinter properties is stability [10].


**Table 9.** *Properties of Fe sinters [10].*
