NIOSH Mining Safety and Health Research

Falls of ground remain the greatest single hazard faced by underground miners. They cause nearly 50% of fatal injuries. When coal is first mined, large pillars of coal are left to support the rock between the mine and the surface. When these pillars are later recovered, the ground collapses. Nationally, coal pillar recovery accounts for just 10% of coal mined underground, but it is linked to more than 30% of roof fall deaths. NIOSH research has addressed the size of the final stump, pillar design when mining depths > 200 m, and preventing massive falls by controlling the pillar width-to-height ratio. A series of meetings was held with the Mine Safety and Health Administration, the West Virginia Office of Miners Safety, Health, and Training, and the West Virginia Board of Coal mine Health and Safety. As a result, many NIOSH guidelines were incorporated into the roof control plans for nearly 100 mines in southern West Virginia. Others have been incorporated into the mining plans of several large mining companies.

A small but growing segment of the mining industry is underground stone. Workers employed in underground stone mines are at higher risk for injury or death than those in other segments of underground mining. To address the health and safety issues of this population, NIOSH annually holds an Underground Stone Safety Seminar. This seminar is held in Kentucky, the heartland of the Nations underground stone mining industry. Last year, more than 200 attendees representing 16 States participated.

Longwall shields provide essential ground control in longwall mining. However, a high percentage of shields are operating at less than peak capacity because of defective hydraulic cylinders or malfunctions in other hydraulic components. NIOSH has developed the Shield Hydraulics Inspection and Evaluation of Leg Data (SHIELD) program to analyze leg pressure data and identify shields that are not performing to rated specifications. The program will help mines establish a proactive preventive maintenance program. It will ensure that the critical roof support provided by the longwall shields is maintained as the shields age.

Most of the approximately 800 nonfatal roof fall injuries to underground coal miners each year are caused by small rocks falling from between roof bolts. Unfortunately, many mines hesitate to use effective surface controls because of the perceived cost. To reduce the barriers to the use of surface control, NIOSH visited 17 underground mines to identify "best practices" in surface control application and performance. These include the use of custom-designed reinforced screen, the application of linked screens to reduce material handling, and the use of bolting machines with advanced material handling systems. A roof damage rating system that can be used to indicate the need for applying skin control was also developed.