## 4 Results and Discussion  
The main objective of this study is to investigate the decline in the overall efficiency and steam output pressure of the boiler(s) operated by Sasol synfuel limited; this challenge might be a result of the coal ash accumulation on the boiler heat transfer tubes. In meeting the research objective, an investigation on the coal ash produced from the coal combustion was carried out to determine the coal ash chemical concentration. The fouling and slagging potential during the boiler operation was predicted using the analysed laboratory results in this study. Fouling and slagging prediction indices developed from previous research work based on the coal ash chemical composition were used as guidelines or evaluation reference point to evaluate the slagging and fouling prediction of the operated Sasol boiler(s). This section entails the presentation and discussion of the analysed laboratory results obtained during the coal ash analysis. Table 1 is a representation of the elemental composition detected from the coal ash samples from the ICP-OES analyser, it shows the major (Ca) and minor (Na, Mg, K, S) elements present within the coal ash. Table 2 is a representation of the elements detected in the coal ash samples from the ICP-MS analyser. these elements make up the trace elements (As, Se, Cd, Hg, Pb) within the coal ash sample. Table 3 represents the detected concentrated elements present in the coal ash samples from the XRF analyser. The major elements presents are Al\({}_{2}\)O\({}_{3}\) and SiO\({}_{2}\). The chemical composition results for the bituminous coal ash in this study agreed with previous research results discussed in Section 2 in this article. \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Element Present** & **Sample A mg/Kg** & **Sample B mg/kg** & **Sample A Mass (\%)** & **Sample B Mass (\%)** \\ \hline Na & 2066.6 & 2804.9 & 0.21 & 0.28 \\ \hline Mg & 3843.3 & 3600.6 & 0.38 & 0.36 \\ \hline K & 774.2 & 894 & 0.08 & 0.09 \\ \hline Ca & 45,971.6 & 58749.6 & 4.60 & 5.87 \\ \hline S & 1412.7 & 669.7 & 0.14 & 0.07 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: ICP-OES elemental analysis. \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Element Present** & **Sample A mg/Kg** & **Sample B mg/Kg** & **Sample A Mass (\%)** & **Sample B Mass (\%)** \\ \hline As & 7.58 & 1.88 & 0.00076 & 0.00019 \\ \hline Se & 5.78 & 3.19 & 0.00059 & 0.00032 \\ \hline Cd & 0.09 & 0.019 & 0.000009 & 0.000009 \\ \hline Hg & 0.10 & 0.018 & 0.00005 & 0.0000018 \\ \hline Pb & 19.3 & 3.55 & 0.0019 & 0.00036 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: ICP-MS elemental analysis. Table 4 is a representation of the elemental composition of the raw bituminous coal used for firing the installed boilers at the Sasol synfuel operation. The published developed fouling and slagging prediction indices based on the ash chemical constituents are summarised in Table 5, indicating the predicting factor, evaluated index (formula), and the predicted fouling and slagging type (i.e., low, medium, high, and severe) based on analysed coal ash chemical constituents. The indices in Table 5 were used as a guide for evaluating the fouling and slagging prediction for the installed Sasol coal-fired boiler(s) using the data set from the analysed laboratory coal ash chemical constituents in Tables 3 and 4. Table 6 is the evaluated fouling and slagging potential prediction of the boiler installed at Sasol synfuel operation in Secunda based on the analysed coal ash chemical composition obtained from the laboratory analysis. Using the evaluated indices and the predicted fouling and slagging types in Table 5 as a guide. The results obtained predict a low to medium fouling potential and a low slagging potential during the operation of the installed boilers at Sasol synfuel limited.