Mechanical properties of rock cutting by disc cutters and feasibility analysis of mechanical mining in Jinchuan No. 3 Mine with hard rock

Disc cutters are essential rock-cutting tools for Tunnel Boring Machines (TBMs), primarily used in hard rock excavation. However, TBMs are not suitable for mining actives due to limitations in size and flexibility. This study first investigates the mechanical properties of rock cutting by disc cutters, and then explores the feasibility of mechanical mining with disc cutter based hard rock mining machines. The ores in the Jinchuan No. 3 Mine represent to typical hard rockmass, with rock strength ranging from about 125 to 180 MPa. The mechanical properties of hard rock cutting are investigated by linear cutting machine (LCM) tests and numerical simulations, showing good consistency between experimental and simulation results. The laboratory results reveal maximum normal forces of 40 kN and 60 kN at penetration depths of 2 mm and 4 mm, respectively, with specific energy (SE) of 7.33 kWh/m³ and 8.42 kWh/m³. The simulation results indicate maximum normal forces of 40 kN and 55 kN. Moreover, simulated crack propagation during rock cutting supports the tensile crack-dominant model, with crack characteristics closely matching existing theoretical analysis and experimental observations. During rock cutting, multiple semi-conical shaped cracks are generated, with their sizes initially decreasing before stabilizing. Simulation of rock cutting with double disc cutters identifies the optimal cutter spacing. Accordingly, a cutter arrangement approach for the wheel-type cutter head of hard rock mining machines is proposed. Finally, the feasibility of mechanical mining in the Jinchuan No. 3 Mine is discussed through estimating mining efficiency and proposing an innovative mining method.