ABSTRACT:
Case-study data from a series of three-dimensional scanning laser tests conducted at the Stillwater Mining Company’s, Stillwater Mine in Nye, Montana, USA is presented. A series of blast rounds in two underground development drifts were scanned using a Leica HDS 3000 Scanning Laser. Detailed digital surveys from the scans were used to supplement basic blast audit data including location and orientation of drill holes, comparison of “as-designed” versus “as-built” and calculations of overbreak and underbreak. Operational considerations and feasibility of using the system as a research tool to quantify blast damage are discussed as well as the safety implications of improving blast designs.
1 INTRODUCTION
1.1 NIOSH Mine Safety Research
The National Institute for Occupational Safety and Health (NIOSH) is currently performing blasting research to help mine operators minimize the amount of loose or damaged rock surrounding a blasted opening. The goal of the research is to show that better perimeter control in underground excavations will decrease the number of accidents associated with ground fall injuries as well as decrease the exposure to hazards associated with scaling and installation of ground support. One component of the project is to develop standardized methods for quantitatively assessing improvements in blast designs. This paper highlights preliminary results from a case study of several drift development rounds at the Stillwater Mining Company’s (SMC) Stillwater Mine, Nye, Montana.
1.2 The primary objective of designing an underground blast round is to fracture the rock mass of a desired excavation according to specific design criteria (e.g., size distribution, muck pile placement, round dimensions, etc.). However, in doing so, the rock adjacent to the opening is commonly fractured and weakened. The damaged ground must be secured before further advancement of the working face can occur.
