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, Australian Centre for Geomechanics, Perth, pp. 293-305, https://doi.org/10.36487/ACG_rep/1511_17_Gao
It is recognised that a gently-dipping narrow vein is hard to be exploited due to the difficulties in ore drawing and operating large mining equipment in the restricted stoping space. Therefore, considerations are required to adopt an efficient mining method that is capable of dealing with the irregular boundary of this kind of orebody, resulting in a high recovery rate while minimising the ore dilution and the preparations prior to stoping. In the case of mining the low-grade ore cluster I-9 at the Kafang Mine of Yunnan Tin Industry Company, China, the requirements of mining at a large scale poses another challenge. For the ore cluster I9, there are four layers of ore bodies, with an average thickness of 2.22 m and dip angles in the range of 1520°. The average grade of the main commodity (Cu) is only 0.58%. After evaluating and comparing different mining methods based on a geotechnical investigation, rock mechanics tests and rock mass classification, the efficient breast stoping (overall mining method) was selected. Specifically, the stopes along the strike direction were arranged at an angle of 45°, with respect to the dip direction (termed apparent dip layout henceforth). This layout enhanced the operating ability of loadhauldump (LHD) and other trackless equipment. With a Sandvik drilling jumbo DD210L and a TCY2A diesel LHD, continuous mining of the full thickness of the orebody significantly increases production when compared with previous mining practice. The ore loss decreases from 14.6 to 8.2%. The extraction-to-cut ratio is down from 20.69.2 m/kt. The mining cost is reduced from CNY 158.88 to CNY 104.35 per tonne. This mining method has the potential to be widely used to exploit similar orebodies.
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