## 2 Materials and Methods
### Refractory Lining Details in Analyzed Zone of Trunions  
A mass analysis of the wear characteristics of the BOF refractory is achieved by comparing the thickness data of the MgO-C refractory lining. The reference point for refractory loss was the first measurement of the brand-new working lining. These data are considered the reference standard against which the entire campaign is measured. In order to determine whether there has been a loss or gain of refractory material within the BOF, subsequent measurements must be carefully compared against the initial reference measurement. This comparative analysis enables the precise assessment of any changes, whether a reduction in refractory thickness due to wear or an increase in thickness indicative of skull formation occurs. Maintaining rigorous monitoring and evaluation of these refractory material fluctuations is crucial for ensuring the optimal performance and lifespan of the  
Figure 2: Schematic drawing of analyzed areas of MgO–C refractory lining in BOF.  
BOF equipment. Chemical and physical parameters of the MgO-C refractory material used in trununion zones are shown in Table 1.  
During the steelmaking process in BOF, a mix of molten steel and slag forms. Over time, this mixture builds up and hardens into deposits on different parts of MgO-C lining and oxygen lance [59]. In the steel industry, these solidified deposits are all called skulls. The varying chemistry of steel and slag during steelmaking makes it difficult to analyze the exact chemical composition of the skulls formed from these materials [8]. The objective of treating the refractory lining in the BOF is to decrease the thickness of the skulls and to maintain the MgO-C lining at an optimal level. To determine skull dimensions, technicians use laser equipment to measure the BOF lining's thickness. A specialized oxygen nozzle is then used in the BOF vessel to decompose and remove these skulls.  
Furthermore, the MgO-C refractory lining of the BOF is subject to deterioration when exposed to excessive heat, oxygen leakage, and prolonged downtime due to excessive cooling of the refractory lining and by subsequent thermal shock. An additional oxygen blow (re-blow) in the BOF raises the temperature and oxidizes both the slag and gaseous atmosphere, thereby accelerating carbon oxidation from the MgO-C refractory and reducing the lining's resistance to slag attack [56]. The prevailing trend in steel production to achieve a higher number of heats per BOF campaign has intensified the demands placed upon both the MgO-C refractory lining and the consumption of refractory spinning mixtures. Chemical and physical parameters of the used gunning refractory mixtures are shown in Table 2.  
\begin{table}
\begin{tabular}{c c c} \hline \hline  & MgO in magnesia & min. 98.0 \\  & SiO\({}_{2}\) in magnesia & max. 0.4 \\
**Chemical** & CaO in magnesia & min. 1.2 \\
**Composition** & Fe\({}_{2}\)O\({}_{3}\) in magnesia & max. 0.5 \\ \cline{2-3}
**(wt.\%)** & Magnesia content & 86.5 \\ \cline{2-3}  & Residual carbon & 13.5 \\  & content & \\ \hline \multirow{3}{*}{**Physical** **Parameters**} & Volumetric mass & min. 2920 kg\(\cdot\)m\({}^{-3}\) \\  & Cold compressive & min. 27 MPa \\ \cline{1-1}  & strength & max. 4\% \\ \hline \hline \end{tabular}
\end{table}
Table 1: Chemical composition and physical parameters of MgO–C refractory material used in trununion zones.  
\begin{table}
\begin{tabular}{c c c} \hline \hline  & MgO & 87.8 \\  & CaO & 7.7 \\
**Chemical** & P\({}_{2}\)O\({}_{5}\) & 2.7 \\
**Composition** & SiO\({}_{2}\) & 1.3 \\
**(wt.\%)** & Al\({}_{2}\)O\({}_{3}\) & 0.4 \\  & Fe\({}_{2}\)O\({}_{3}\) & 0.1 \\ \hline \multirow{2}{*}{**Physical** **Parameters**} & Operating temperature & 1750 \({}^{\circ}\)C \\  & Granularity & 0–3 mm \\ \cline{1-1}  & Volumetric mass & 2200 kg\(\cdot\)m\({}^{-3}\) \\ \hline \hline \end{tabular}
\end{table}
Table 2: Chemical composition and physical parameters of gunning refractory mixtures used in trunion zones during campaign.