**3. Results**

*Iron Ores*

**Table 1.**

**Basicity CaO/SiO2**

*The planned basicity values of each kind of mixtures.*

**82**

**2. Methods**

*The RDI values of the chosen sinters.*

**Figure 2.**

*Metalurgii* Ż*elaza.*

**Sinter RDI values**

**Sinter RDI values**

**Table 2.**

a diffracted beam). The range of 2θ was 10o

In XRD method, the first step was to reduce a crystallite size of the sinters, using Fritsch Puverisette 0 mill and also a mortar and a pestle. The measurements of diffraction patterns were carried out using a PANalytical Empyrean diffractometer with a PIXcel solid state detector and filtered Co Ka radiation (Fe filter on

*The experimental site for sintering iron ores and waste products in Sie*ć *Badawcza* Ł*ukasiewicz - Instytut* 

**RDI-1+6.3 39,5 40,2 45,9 46,2 50,2 51,5 44,3 51,1 55,8 RDI-1-3.15 29,9 28,7 26,1 26 22,6 22,4 21,3 17,2 18,8**

**RDI-1+6.3 54,9 55,2 52,8 39,7 36,6 39 51,3 53,7 52,6 RDI-1-3.15 14,3 15,2 14,9 32,4 32,9 33,5 20,8 19 19,1**

**A1 A2 A3 B1 B2 B3 C1 C2 C3**

**Series A Series B Series C Series D Series E Series F**

**1,20 1,20 1,50 1,50 0,90 1,20**

**D1 D2 D3 E1 E2 E3 F1 F2 F3**

International Centre for Diffraction Data (ICDD) Powder Diffraction File PDF-4+. The quantities of individual phases were calculated by means of the Rietveld

and time/step 800 s. The identification of phases was done according to


with step size Δ2θ = 0.02626<sup>o</sup>

Generally, two groups of minerals can be distinguished in sinters: oxides and silicates. The examined sinters contained two iron oxides: hematite Fe2O3 and magnetite Fe3O4 and one silicon dioxide – quartz SiO2. Only traces of wuestite FeO were found. The group of silicates consisted of calcium silicates (larnite β-CaSiO4, γ-CaSiO4, wollastonite CaSiO3), calcium-iron silicates (hedenbergite Ca0.5Fe1.5Si2O6, kirschsteinite CaFeSiO4), magnesium silicate MgSiO3 and so called silica glass (amorphous component). There were also three so called slag phases identified in the sinters: Ca2.3Mg0.8Al1.5Fe8.3Si1.1O20 (SFCA phase), Ca3.18Al1.34Fe15.48O28 (SFCA-1 phase) and Ca2.45Fe9.2Al1.74Si0.6O20 (SFCA Mg – free phase).

All measured diffraction patterns of the examined sinters were characterized by a strong complexity because of many reflexes of individual phases and overlapping of the reflexes. In **Figure 2**, a part of a diffraction pattern of one of the sinters is shown and the positions of reflexes of all crystalline components, according to PDF-4+ standard data, are clearly visible. In a typical experimental range of 2θ (10o – 100o 2θ) there were about:


and also reflexes of other constituents. This was a result of low symmetries of some of the phases forming a sinter. There are all identified phases and their space groups in **Table 3**.

With such a complexity of the diffraction patterns, the only solution was to apply the Rietveld method [1–6]. A model of a sinter file was created, containing all structural data of all identified crystalline components. Two numerical criteria of fit were taken into account: χ 2 and *R-pattern*. The global parameter of the refinement was 2θ- *zero.* Pearson VII was chosen as an analytical profile function. For each phase, the refined parameters were: scale, lattice parameters, full-width-at-halfmaximum (FWHM) parameters. The background was removed manually.

The example of the Rietveld refinement is presented in **Figure 3**. The upper line is the experimental pattern (as measured). The higher intensity of the background in the range of lower angles is indicated and it is concerned with a presence of amorphous component. Below, there is the experimental pattern after removing background (points) and the calculated refined diffraction pattern (solid line). At the bottom, a difference plot is shown.

During the refinements, the difference plots were carefully observed. In some cases, the identification of a phase of a small content was possible during the analysis of a shape of a difference plot.


#### **Table 3.**

*Space groups of sinters' crystalline components.*

#### **Figure 3.**

*An example of the Rietveld refinement of a diffraction pattern of one of a sinter. The upper line is the experimental pattern (as measured). Below, there is the experimental pattern after removing background (points) and the calculated refined diffraction pattern (solid line). The higher intensity of the background in the range of lower angles is concerned with a presence of amorphous component. At the bottom, a difference plot is shown.*
