Technology News 389 - new ideas for keeping miners away from unsupported roof.
Pittsburgh, PA: U.S. Department of the Interior, Bureau of Mines, TN 389, 1991 Sep; :1-2
Objective: Improve the health and safety of underground mine workers by finding ways of keeping them away from unsupported areas of the mine. Background: Roof falls have been the leading cause of fatal accidents in the underground coal mining industry. During 1985-89, 92 coal miners were killed by falls of roof and rib, with more than 4,000 miners injured. According to accident investigation reports from the Mine Safety and Health Administration, 47% of the victims of the fatal roof fall accidents were in the area of unsupported roof at the time they were killed. There is an urgent need to find out why miners go under unsupported roof and to devise strategies for preventing this unsafe behavior. Approach: To discover what can be done to prevent miners from going under unsupported roof, confidential interviews were conducted with 297 miners who work in the face crews of 6 different coal mines. The interview topics included company policies and actions regarding going under unsupported roof, how foremen react to people who go under unsupported roof, circumstances likely to cause some people to go under unsupported roof and how to prevent these situations, and observations concerning those who go under unsupported roof. Interview Findings: The following ate a few of the findings from the interviews: (1) When asked how likely it is that their foreman would report them if he or she saw them go under unsupported roof twice within the same week, 53% of the interviewed miners indicated "likely," 22% said they had no idea, and 25% said "unlikely." (2) 82% stated that they could recall an instance in which they had unintentionally gone under unsupported roof. Of those who could recall such an instance, 24% indicated that the most recent incident had occurred within the past month. (3) 49% indicated that they had seen a coworker under unsupported roof within the past 6 months. Of those who reported having observed this, 72% stated that they believed the person was aware that he or she was inby supports, i.e., that it was an intentional act. When asked what the coworker was doing while under unsupported roof, the activities mentioned most frequently were: 1. Walking through unbolted crosscuts; 2. Operating a continuous miner; 3. Hanging or extending ventilation tube; 3. Retrieving things left laying on the ground; 4. Marking the roof for bolts; 5. Rock dusting; 6. Operating a scoop; 7. Repairing or restoring power to a remote continuous miner; 8. Examining a roof fall; 9. Operating a roof bolter. The interviewees identified several ways to modify equipment and work procedures that would hopefully eliminate many of the circumstances that cause people to go under unsupported roof. One problem is the proper positioning of a roof bolting machine prior to installing a new row of bolts. Going inby the last row of bolts to measure and mark the roof prior to installing the next row of bolts is unsafe because unsupported roof could unexpectedly fall on the person measuring the roof. One employee at a coal mine in eastern Ohio came up with an innovative idea for eliminating the need for anyone to get close to unsupported roof in order to determine the proper spacing between rows of bolts. He suggested welding flexible wire antennas onto the bolter's temporary roof support system. These antennas serve as a convenient gauge for determining whether the next row of bolts is going to be spaced the appropriate distance from the rib and from the last row of bolts bordering the area of unsupported roof. This simple equipment modification allows bolting machine operators to establish the proper spacing between bolts quickly and accurately, and eliminates the need for anyone to go near unsupported roof to take measurements.
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