## 2 Measurement and Roughening Methods
### Roughening Methods
#### 2.2.1 Grinding Method
\begin{table}
\begin{tabular}{p{56.9 pt} p{56.9 pt} p{56.9 pt} p{56.9 pt}} \hline
**Minerals** & **Methods** & **Particle Size/\(\mu\)m** & **Findings** \\ \hline quartz [41] & AFM & 38–74 & The ceramic ball-milled quartz particles (Ra = 1.16 nm) had a higher surface roughness than that of the stainless steel disk-milled ones (Ra = 0.52 nm). \\  & & & The rod-milled quartz particles (Ra = 4.24 \(\mu\)m) exhibited smoother surfaces than the ball-milled (Ra = 4.49 \(\mu\)m) and autogenous-milled (Ra = 4.30 \(\mu\)m) ones. \\  & & & Compared with the surface of the ball-milled spodumenes (Ra = 0.87 nm), more protrusions were observed on the surface of the rod-milled ones (Ra = 1.14 nm). \\  & & & The ball-milled (Ra = 0.68 \(\mu\)m) and rod-milled (Ra = 0.55 \(\mu\)m) particles showed a higher and lower surface roughness compared with that of autogenous-milled particles (Ra = 0.66 \(\mu\)m). \\ hematite [39] & AFM & 55–74 & The surface roughness for the ball-milled particles (Ra = 8.5 nm) was larger than that for the rod-milled ones (Ra = 2.1 nm). \\  & & 104–147 & The autogenous-milled particles showed a lower surface roughness than that of ball-milled ones for all the fractions. \\  & & 44–53 & The ceramic ball-milled magnesite particle surfaces (Ra = 1.59 nm) were rougher than that of the stainless steel-milled ones (Ra = 0.28 nm). \\  & & 104–147 & The surface roughness values for ball-milled pyrite \\  & & 53–74 & The vitreous-milled particles showed a lower surface roughness than that of ball-milled ones for all the fractions. \\  & & 44–53 & The ceramic ball-milled magnesite particle surfaces (Ra = 1.59 nm) were rougher than that of the stainless steel-milled ones (Ra = 0.28 nm). \\  & & 104–147 & The surface roughness values for ball-milled pyrite \\ pyrite [66] & BET & 53–74 & The vitreous-milled particles were lower than all fractions of autogenous-milled pyrite products. \\  & & 44–53 & The surface roughness of magnesite particles \\  & & & ground by the vertical roller mill and the ball mill was about 0.19 nm and 0.10 nm, respectively. \\ graphite [38] & AFM & 150–180 & The Ra value of graphite particles produced by the ball mill and high-pressure grinding roller was 0.667 nm and 1.350 nm, respectively. \\  & & & The roughest and smoothest product for calcite was the autogenously ground product and rod-milled product, and that for barite was the autogenous-milled and ball-milled ones, whereas for talc and quartz it was the ball-milled and rod-milled products. \\  & & & The roughness of the coal particles was 1.1028 for the ball-milled ones, measured by the BET method, and it increased to 1.1134 and 1.1089 upon grinding with the disk mill and jaw crusher. \\ \hline \end{tabular}
\end{table} 
Table 2: _Cont._et al. [67] demonstrated that the pyrite particles ground using iron mediums had a higher surface roughness than those ground in ceramic mediums. [PERSON] et al. [2] produced malachite particles with a varying surface roughness by grinding malachite samples alongside quartz (Mohs hardness: 7) or montmorillonite (Mohs hardness: 1-2). Their findings indicated that the malachite ground with quartz displayed a greater surface roughness compared to that ground with montmorillonite. [PERSON] et al. [74; 75] discovered that the addition of grinding aids in dry grinding increased the surface roughness of magnetite. In terms of grinding environment, [PERSON] and [PERSON] [76] and [PERSON] [77] explored the impact of the dry and wet grinding methods on surface roughness. They noted that dry-ground samples had relatively rougher surfaces when compared to wet-ground samples with the same particle size distribution. This observation was supported by [PERSON] et al. [78], [PERSON] et al. [79], and [PERSON] et al. [65], who reported that the surface roughness in dry grinding was higher compared to wet grinding, which, in turn, affected the flotation behavior. Regarding grinding time, [PERSON] et al.