## 3 Materials and Methods
### Relevance of Methodology  
Assessing the relevance of the developed methodology refers to ensuring that granulation in laboratory and industrial scales generates slags with comparable properties. For this purpose, a spot sample of water-granulated iron silicate copper slag, with a true density of 3.44 g/cm\({}^{3}\), was collected from Boliden Ronnskar in Sweden. The sample was taken afterthe dewatering process, as illustrated in the flow sheet presented by [PERSON] et al. [49]. After drying the slag, representative samples were generated with a Jones riffler, and each analysis or experiment using the industrial slag described in the text below was performed on such a subsample. The bath temperature in the settling furnace, from where the industrial slag is tapped and granulated, was unknown for the slag used in the present study. However, reported operational temperatures vary between 1210 and 1288 \({}^{\circ}\)C [45; 50]. Furthermore, toward the end of tapping the furnace, temperatures exceeding 1300 \({}^{\circ}\)C are common due to continued electrical heating [50]. Therefore, three samples were generated in the laboratory scale experiments, each distinguished by their designated homogenization temperature in the laboratory scale furnace, i.e., 1200, 1300, and 1400 \({}^{\circ}\)C. As such, the relevance of this methodology was evaluated based on the original slag, granulated on an industrial scale, and the three laboratory-scale samples remelted in iron crucibles and granulated according to the procedure outlined in Section 3.1. The nomenclature used to refer to the samples is presented in Table 2.  
The chemical composition of the original slag was determined by X-ray fluorescence (XRF) spectrometry on a pressed powder sample. For the analysis, a SPECTRO XEPOS energy dispersive XRF spectrometer (SPECTRO, Kleve, Germany) equipped with binary palladium-cobalt anode was used. The instrument was calibrated with in-house standard samples from Boliden Ronnskar. The four-slag samples were ground individually using 45 mL tungsten carbide grinding bowls in a FRITSCH Pulverisette 7 planetary ball mill (FRITSCH GmbH, Idar-Oberstein, \begin{table}
\begin{tabular}{c c c} \hline \hline
**Label** & **Granulation** & **Temperature [\({}^{\circ}\)C]** \\ \hline Original slag & Industrial scale & Unknown 1 \\
1200 \({}^{\circ}\)C & Laboratory scale & 1200 \\
1300 \({}^{\circ}\)C & Laboratory scale & 1300 \\
1400 \({}^{\circ}\)C & Laboratory scale & 1400 \\ \hline \hline \end{tabular} \({}^{\dagger}\) Elaborated in the text.  
\end{table} 
Table 2: Sample list for evaluation of relevance. Figure 6: Overview of the experimental setup. Germany). Two separate cycles were employed to reach a fine particle size distribution without excessive time spent under grinding. The first cycle was performed at 600 revolutions per minute (RPM) for 3 min using 7 WC balls of 15 mm in diameter. Subsequently, a second cycle of fine grinding was performed using 180 WC balls of 5 mm in diameter for 1 min at 600 RPM. The coarse grinding was based on roughly 12 mL of a representative sample of slag granules, and the fine grinding was, subsequently, performed on the material from the first step. Rietveld powder X-ray diffraction (XRD) with an internal standard was used to determine the amorphous content of the four slags. Based on possible present phases, calcite (99.5% CaCO\({}_{3}\)) was determined to be a suitable internal standard to avoid overlapping peaks. In accordance with the published literature [23; 31; 51], the chosen internal standard was mixed to obtain 10 wt.% in the samples. Mixing was made using a ring mill, and the subsequent scans were performed between 10 and 90 \({}^{\circ}\)20 with copper K\({}_{\alpha}\) generated at 45 kV and 40 mA using a Malvern Panalytical Empyrean X-ray diffractometer (Malvern Panalytical, Malvern, UK). The refinement was performed using HighScore+ and the COD database [52].