# Separation of Iron Oxide from Harbor Waste Using Selective Flocculation
## 3 Results
### SEM-EDS and XRD Analyses  
Scanning electron microscopy with energy-dispersive spectroscopy (SEM-EDS) and X-ray diffraction (XRD) are complementary techniques that have been extensively employed in previous studies for the detailed characterization of mineralogical samples. Their combined use has significantly advanced the understanding of mineral compositions and microstructures, particularly in studies involving mineral separation and waste characterization [16]. For mineral processing and waste management, knowing the exact composition and structure of the waste is crucial. Previous studies have used the insights gained from both techniques to optimize separation methods--such as adjusting the selective flocculation parameters--to target specific mineral phases more effectively [17]. SEM-EDS analysis of the unpolished polymineral aggregate--sample K--revealed the presence of grains with a maximum size of up to about 400 \(\upmu\)m. On the surface of the most grains, agglomeration of powders of small particle sizes, different in chemical compositions, can be observed. Grains with clearly visible heterogeneity were analyzed in the form of points, as shown in Figure 2, while the results of semiquantitative EDS chemical analysis normalized to 100% are given in Table 4. \begin{table}
\begin{tabular}{c c c c c c c c c c} \hline \hline  & **C** & **O** & **Al** & **Si** & **Fe** & **Ca** & **K** & **Mg** & **Ti** & **Total** \\ \hline Spectrum 1 & 76.00 & 20.38 & 1.15 & 0.98 & 1.49 & 0.00 & 0.00 & 0.00 & 0.00 & 100.00 \\ Spectrum 2 & 17.57 & 43.33 & 6.53 & 6.56 & 19.53 & 5.01 & 0.44 & 0.73 & 0.32 & 100.00 \\ Spectrum 3 & 0.00 & 41.05 & 3.61 & 3.64 & 49.51 & 2.19 & 0.00 & 0.00 & 0.00 & 100.00 \\ Spectrum 4 & 62.18 & 33.02 & 1.23 & 1.10 & 2.46 & 0.00 & 0.00 & 0.00 & 0.00 & 100.00 \\ Spectrum 5 & 23.51 & 43.86 & 2.91 & 2.83 & 25.80 & 0.48 & 0.37 & 0.00 & 0.24 & 100.00 \\ Spectrum 6 & 0.00 & 29.41 & 3.60 & 1.79 & 65.19 & 0.00 & 0.00 & 0.00 & 0.00 & 100.00 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Semiquantitative chemical composition of sample K, obtained by EDS analysis. Figure 1: Particle size distribution of sample K.  
EDS analysis determined that the grains representing the dominant phase of sample K mostly composed of carbon (up to 80% by weight) and oxygen, while smaller individual grains were composed of iron and oxygen. A low content of Al and Si was observed in both phases. Their presence may be the result of fine-grained clay aggregates or mica minerals (with lower potassium and magnesium content) on the surface. Titanium is sporadically found in concentrations lower than 0.5% and cannot be associated with any analyzed phase. The morphology of the grains that contain carbon and oxygen is most similar to coal--anthracite grains. They are fragments irregular and polyhedral in shape with sharp corners and rough surfaces as well as flat surfaces. Using the SEM-EDS method on unpolished separated fractions (K1, K1M, K2, K2M, K3, and K3M), the morphology and chemical composition were analyzed in points and fields on the present grains as well as the concentrations of individual elements in the form of maps. Given that the examined samples were unpolished, the mineralogical identification of the phases with this method was further complicated because even after sieving and separation of fractions by size and separation with a magnet, completely homogeneous grains could rarely be observed. There are mostly grains that represent a kind of composite composed of at least two phases as well as grains that contain fine-grained particles of other phases on their surface. This is present in all investigated fractions, especially in K1 (Figure 3). Such examples are significantly less represented in the smallest fraction, and the grains are more homogeneous, which facilitated the identification of mineral phases.