NIOSH Mining Safety and Health Research

Thousands of tons of ore, mining waste products, and supplies and equipment are transported each day in the mining industry. The vast amount of such materials and the large scale of the systems and equipment used to move this material create the potential for serious injuries. NIOSH Mining researchers are investigating innovative ways to reduce the dangers inherent in such work through redesign and development of equipment, modification of work practices, and transfer of information.

One project is looking at ore passes, which are used to feed bulk materials such as ore or waste rock from various mining levels to load-out skips usually positioned at the bottom of a mine for transport to the surface. Since 1983, 28 fatalities related to ore pass operations have been reported. Miners have been pulled into flowing rock, fallen into open holes, and struck or buried by rock under chutes. Inconsistent rock flow, changes in flow dynamics, and failure of chute structures have been the cause of some of the fatalities. Proper chute design is important to reduce the incidence of chute failure and resulting injuries.

The Galena Mine in northern Idaho transfers rock using gravity, dropping ore and waste over 1000 feet via two ore passes. These passes utilize a steel chute and pneumatically operated knife gate design. The 6-foot in diameter ore passes are inclined 80° and terminate at the chute. Rock flow is redirected just above the chute from the 80° incline in the ore pass to a 45° incline in the opposite direction at the chute.

Strain is being measured at five locations on the chute gate and the chute frame using 350-ohm strain gauges. Data are being collected using the miniature data acquisition system (MIDAS). Static pressure is monitored from forces applied to the chute assembly from rock dumped into the ore pass. Measurements will provide insight into the range of rock pressures on the chute gate and frame when using this ore pass configuration.

Design drawings and fabrication details for the mobile manipulator systems turret-arm lock subsystem have been completed, and the subsystem is under construction at Wheeler Industries, Spokane, WA.