A Method to characterize risk associated with mine roof conditions

• Other Authors: Savanick, George A., Miller, Arthur L., Pittsburgh Research Laboratory (National Institute for Occupational Safety and Health)
• Language: English
• Subjects: Jet Pumps; Gravel; Slurry; Gold; Boreholes; Permafrost; Nozzle; Ice; permafrost
• Online Access: http://stacks.cdc.gov/view/cdc/8297/

"Assess the technical feasbility of mining small and/or deeply buried frozenplacer deposits from the surface through boreholes. Placer deposits in permafrost often contain up to 15% cobbles and boulders. Because of erratic loading on the bit caused by elasticity and heterogeneity of the ice-and-gravel matrix, these deposits are extremely difficult to excavate. The approach taken in this research project was to mine only the ore-bearing portion of the deposit using a high-pressure water jet to thaw the gravels and a downhole hydraulic-lift-type pump to bring the ore to he surface as slurry. Full-scale jetting tests in frozen gravel were completed, and the data were used to design a jet excavator. The excavator will deliver a water flow of 890 L/min through a 15.7 mm diam nozzle at 6,900 kPa. The prototype slurry pump was designed to lift minus 15 cm gravels to the surface from a depth of 15 m." - NIOSHTIC-2 NIOSHTIC no. 20000466