Investigations on Rockmass Structure Characteristics and Mechanical Mining Efficiency and Economics in the Jinchuan No. 3 Mine With Hard Rock

Geomechanical characterization is crucial for assessing the feasibility of the mechanical construction method in geotechnical engineering, which is a construction method that neither uses explosives nor involves blasting operations. But for hard rock mines, relying solely on rock strength data is insufficient to estimate the applicability of cantilever roadheaders. The rockmass structure characteristics are also essential, as mechanical mining can be highly effective in hard rock mines with well-developed rockmass joints. For instance, rock specimens from the Jinchuan No. 3 Mine exhibit a strength of about 150 MPa. When joint spacing is less than 400 mm, the efficiency and economics of mechanical mining using a cantilever roadheader are significant. Field experiments demonstrate a mining rate of 1.8 m/h, and the ore cutting cost of the mechanical mining method can be reduced by more than half compared to drilling and blasting methods. Conversely, if the joints within the hard rockmass are poorly developed, mining efficiency and economics are unacceptable. Moreover, artificial intelligence (AI)-based visual recognition is a promising tool for estimating rockmass joint attributes and assessing the feasibility of mechanical mining in hard rock mines, according to the preliminary application in the Jinchuan No. 3 Mine.