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The effect of water jet distance (in cm) from the coal face and operating time on hydro-mining effectiveness in terms of the depth of the mined coal face spot.
| Pressure (MPa) | Operating time (s) | ||||
|---|---|---|---|---|---|
| 60 | 120 | 180 | 240 | 300 | |
| 20 | 1 | 2 | 2 | 2 | 2 |
| 40 | 4 | 4 | 5 | 5 | 6 |
| 60 | 7 | 8 | 8 | 9 | 9 |
| 80 | 10 | 11 | 11 | 11 | 11 |
| 100 | 10 | 12 | 13 | 13 | 13 |
