Application of Remote Intelligent Control System for Raise Boring Equipment in Slot Raise Construction

Slot raises are critical stope-preparation structures in the open-stope subsequent filling mining method. The construction quality of slot raises directly determines the blasting performance of cutting grooves, and further influences the production capacity and ore fragmentation indicators of large-scale ore caving in stopes. Conventional raise boring equipment is manually operated by on-site underground operators. Working personnel are exposed to underground environments with heavy dust, high noise and potential rock-fall hazards, facing prominent occupational health and safety risks.

Under manual operation, thrust, torque and rotation speed are adjusted purely based on operators’ experience. When crossing fractured zones and heavily jointed rock formations, mismatched drilling parameters may easily lead to drill sticking, excessive pilot-hole deviation and abnormal roller-cutter wear. Construction efficiency fluctuates significantly and performance is highly dependent on operator proficiency. With the advancement of smart mining, man-machine separation and unmanned operation for high-risk underground processes have become key industry trends. Targeting fractured and complex orebody conditions at a porphyry copper mine in Shanxi, a 5G-based remote intelligent control system for raise boring equipment is developed to realize fullprocess autonomous operation for pilot-hole drilling and reaming of slot raises, which is validated through industrial field tests.

1 Pain Points of Traditional Slot Raise Construction

1. High safety risks: Operators must work beside the raise boring equipment underground. Rock fall hazards exist around the raise opening, together with noise and dust-related occupational hazards.
2. Heavy reliance on manual experience: Judgement of rock conditions varies among operators. Improper matching of thrust and torque frequently causes drill sticking and excessive hole deviation in fractured formations.
3. Lack of complete real-time data logging: Drilling parameters including pressure, torque and penetration rate are not systematically recorded, making post-mortem fault analysis difficult.
4. Poor adaptability to fractured zones: Pilot-hole deviation and hole collapse readily occur in broken surrounding rock sections, requiring repeated hole sweeping and causing severe schedule delays.

2 Overall Scheme of the Remote Intelligent Control System

The system consists of six major modules: underground raise boring equipment body, multi-sensor acquisition unit, underground 5G communication module, surface remote control station, intelligent algorithm controller and video monitoring subsystem.

Original hydraulic actuators of the raise boring equipment are retained, while multiple sensors are added to monitor feed thrust, rotary torque, rotational speed, drill-rod penetration depth, hydraulic oil temperature and vibration. All operational data collected underground are transmitted via low-latency underground 5G private network to the surface remote console. Multi-pan-tilt-zoom cameras stream real-time video of underground working conditions, achieving man-machine separation and surface remote operation.

A hill-climbing algorithm is adopted for dynamic parameter optimization. Taking real-time penetration rate as the optimization objective, the system iteratively adjusts feed thrust and rotational speed. When rock hardness increases and penetration drops, thrust is moderately raised. If sharp torque surges are detected as precursors of drill sticking, feed thrust is automatically reduced and rotary speed increased for risk mitigation, without human intervention.

Two operation modes are available: manual remote mode and fully-autonomous drilling mode. After positioning and hole-opening in autonomous mode, the equipment completes pilot-hole drilling, drill-rod make and break and adaptive parameter adjustment automatically. Once the pilot hole breakthrough is achieved, reverse reaming starts with continuously self-tuned reaming parameters. Integrated fault diagnosis triggers real-time alarms and logs events for over-high oil temperature, abnormal pressure and sensor malfunctions.

3 Industrial Test Conditions

Test site: A porphyry copper mine in Shanxi, slot raise construction. Geological conditions: Surrounding rock is well developed with joints and fractures and multiple fractured zones are encountered. Uniaxial compressive strength of rock ranges from 80-120 MPa. Local highly-fractured rock mass presents unfavorable conditions for raise boring. Construction objective: Slot raise with designed depth of 52 m and reaming diameter of 1400 mm. Equipment configuration: Raise boring equipment retrofitted with the remote intelligent control system, complete with drill rods, reaming cutter head and roller cutters.

4 Industrial Test Results

One full-cycle slot raise project of 52 m depth was completed, including pilot-hole drilling and reverse reaming.

1. Drilling efficiency: Average pilot hole penetration rate reached 75 m/h; average reaming penetration rate hit 1.375 m/h. While passing through fractured zones, the system automatically lowered thrust to avoid sticking, with zero drill-sticking downtime.
2. Boring accuracy: Measured final pilot hole deviation rate was 68%, complying with mine acceptance criteria for slot raises. Compared with 1.2%-1.8% average deviation of conventionally manually-operated raise boring equipment in the same mine area, boring accuracy is substantially improved.
3. Safety performance: Operators perform all tasks from a safe underground chamber on the surface side. No personnel are required to stay in high-risk zones adjacent to the raise boring equipment, eliminating rock-fall and mechanical injury hazards.
4. Full-cycle data recording: Complete datasets of torque, pressure, rotation speed and penetration are stored for parameter review in future projects.

5 Existing Limitations and Improvement Suggestions

1. Underground 5G signal fluctuates due to roadway shielding. Additional signal relay nodes will be deployed to further reduce communication latency.
2. Parameter tuning alone has limits for formations with severe hole collapse. While drilling inclino meter modules will be integrated to further enhance pilot-hole trajectory control.
3. Roller cutter wear on cutter heads is currently inspected post operation. Vibration feature recognition will be implemented to enable online prediction of cutter wear.

6 Conclusions

The 5G enabled remote intelligent control system with hill climbing dynamic optimization realizes man machine separated autonomous construction for slot raises using raise boring equipment. Under complex geological conditions with fractured zones in porphyry mines, penetration rates of 1.75 m/h for pilot-hole drilling and 1.375 m/h for reaming are achieved, with a deviation rate of 0.68%. This solution addresses major pain points of conventional manual operation, including prominent safety hazards and heavy dependence on operator experience. It delivers a practical technical approach for unmanned slot raise construction in underground mines, and can be extended to ventilation raises, back fill raises and ore pass applications