Development and application of MWD system for DTH drilling rig

The researches on the measurement while drilling (MWD) technology in the field of open-pit mining are still in the early stage, and the development of MWD systems is the primary task to realize the application of MWD technology in the mining engineering industry. Based on the working principles of the TAIYE-390-Ⅱ hydraulic DTH drilling rig, the MWD parameters and a universal measurement method are respectively determined, and the corresponding measurement devices are developed. The devices mainly include a data acquisition system, a data conversion system, and a data processing system, which can realize the real-time and accurate measurement, acquisition, calculation, storage, display and remote transmission of parameters such as drilling time, depth, penetration rate, axial force, rotation torque, rotation speed, percussive air pressure and air quantity. With the MWD data from a limestone mine, a data integration method that can reflect lithological variations is proposed, and the feasibility of MWD in the structural identification of rock mass is analyzed through the borehole imaging experiments. The results indicate that the penetration rate and rotation torque exhibit the highest sensitivity to rock mass structures. The air quantity and air pressure are more sensitive only when drilling fragmented rock masses with cavities, while the axial force and rotation speed have limited influences on the structural identification of rock mass. The research findings are of important theoretical significance and practical value in the development of MWD systems for DTH drilling rigs and lithological identification.