## 4 The Results of the Experimental Studies  
Potash ore cutting with a single cutter is a complex multifactorial cycle process of alternation of phases of contact crushing and the formation of large cleavages. The separation of each large cleavage from the mass is followed by the formation of the bulb of pressure and inelastic deformation of the potash ore. The cuttings products contain both large elements and dust particles. Propulsion parameters of the rock-breaking mechanism of the samples by cuttings from a leveled surface were analyzed using three oscilloscope waveforms (Figure 5a) obtained under equal conditions (\(h=10\) mm, \(t/h>7.2\)). The average value of the cutting force was \(P_{zl}=2400\) N, which made it possible to determine the cutting resistance \(A_{c}\) of the tested potash ore block:  
\[A_{c}=\frac{P_{zl}}{hk_{b}}=\frac{P_{zl}}{h\left(0.16+0.042b_{p}\right)}=\frac {2400}{10(0.16+0.042\cdot 10)}=414\text{ N/mm}, \tag{8}\]  
where \(k_{b}\)--influence coefficient of the width of the cutting edge. The value of the coefficient \(k_{b}\) is determined empirically. It characterizes the difference between geometrical parameters of the cutter used in these studies and the parameters of the reference cutter, which is used to determine the cutting resistance \(A_{c}\) in the known approaches. Comparison of the value of the cutting resistance \(A_{c}\) obtained experimentally with the known values determined by the employees of the VNII Galurgii sectoral research institute for sylvinite of the BKPRU-4 mine confirms the high reliability of the experimental results [23]. Spectral density allows assessing the frequency distribution of the cutting force. There is an isolated surge of the spectrum in the Figure 5b, at a frequency of 2 Hz, which characterizes the frequency of the formation of a large cleavage in the cutting. The research procedure provides for the determination of the grain-size distribution of the rock-breaking mechanism of the potash ore by cutting from a leveled surface and for the calculation of the specific energy costs of the cutting process. The results of the screening of the ore separated from the block are presented in the Table 1.  
The value of the root-mean-square deviation of the cutting force during the potash ore cutting sample by the cutting from a leveled surface at \(h=10\) mm was \(\sigma_{cl}=1045.8\) N. Specific energy costs of the rock-breaking mechanism of the potash ore by cutting from a \begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{**Boundary Particle Sizes, mm**} & \multicolumn{4}{c}{**Mass Content of the Fractions**} \\ \cline{2-7}  & **Cuttings from a Leveled Surface** & **Staggered Cutings** & **Cross Cuttings** \\ \cline{2-7}  & **gram** & **\%** & **gram** & **\%** & **gram** & **\%** \\ \hline \(\geq\)5 & 56.46 & 71.91 & 124.00 & 75.99 & 99.40 & 72.92 \\ 3-5 & 3.20 & 4.07 & 5.60 & 3.43 & 6.30 & 4.81 \\ 1-3 & 9.60 & 12.22 & 14.55 & 8.92 & 12.80 & 9.78 \\ 0.5-1 & 3.60 & 4.58 & 8.40 & 5.15 & 6.07 & 4.64 \\ 0.25–0.5 & 2.77 & 3.53 & 5.82 & 3.57 & 4.13 & 3.15 \\ \(\leq\)0.25 & 2.90 & 3.69 & 4.80 & 2.94 & 2.23 & 1.70 \\ Total & 78.53 & 100 & 163.17 & 100 & 130.93 & 100 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Grain-size distribution of the potash ore separated from the sample during bench tests. Figure 5: Change in the cutting force \(P_{z}\) (**a**,**c**,**e**) and spectral density \(Q(t)\) of the cutting force (**b**,**d**,**f**) during the destruction of the samples with a single cutter: **a**,**b**—c**uttings from a leveled surface; **c**,**d**—staggered cuttings; **e**,**f**—cross cuttings. leveled surface is \(H_{ul}\) = 3.6 kW\(\cdot\)h/m\({}^{3}\), which corresponds with the results of the previously performed similar studies [11]. The study of the rock-breaking mechanism of potash ore was carried out according to a staggered pattern with a cutting step of \(t\) = 35 mm and a cutting depth in relation to the layer of previous cuttings \(h_{c}\) = 5 mm (the total thickness of the cleavage was \(h\) = 10 mm).