Noise Source Identification Project Draglines, Shovels & Air Arc Cutting Team Members Richard Gates, Assistant District Manager - District 9 Bob Cornett Michael S. Horbatko Michael L. Lynham Robert Smith Peter Saint

Noise Source Identification Project Draglines Background Information MSHA has conducted noise surveys on over 220 operators/oilers. Although the sound pressure levels ranged from 96 dBA to 112 dBA, only 12.5% had exposures above the PEL.

Noise Source Identification Project Draglines Oilers are required to perform various tasks in the dragline house. The time required to perform these tasks varies from day to day. It ranges from 30 minutes to greater than 2 hours.

Major Noise Sources Dragline House The major noise sources connected with dragline houses are: House Fans Motor Generating Sets Wall Fans Motor Cooling Fans Swing, drag, hoist and propel motors

Noise Source Identification Project Potential Noise Controls A meeting pertaining to “Achieving MSHA Noise Standards on Draglines” was held in December, 2000 at Milwaukee, WI. The meeting was sponsored by Bucyrus International. It was attended by MSHA/NOISH, mine operators, dragline manufacturers, and noise abatement consultants. The purpose of the meeting was to share: 1. Information what steps have been taken to comply with MSHA’s noise standard. 2. Information on current noise control methods and, 3. Strategies on achieving compliance with MSHA’s noise standards.

Noise Source Identification Project Potential Noise Controls  Silencers  Vibration Isolation  Fan Blade Damping (coating)  Change of Fan RPM  Automatic Fan Control  Isolation/Barrier

Noise Source Identification Project Potential Noise Controls Current Developments Currently, the most effective means of controlling exposure to noise is to use administrative controls to limit the amount of time spent in the dragline machine house. Remote monitoring using cameras can be used to reduce the time necessary for dragline operators/oilers in the dragline house. P & H Mining Company is developing methods for quieting motor cooling fans in the machine house of their shovels.

Noise Source Identification Project Air Arc Cutting Background Air arc cutting is used to cut dragline or shovel buckets to remove defective parts or to gouge out cracks found in the frames of draglines or buckets. A copperclad, carbon rod is used to create an arc that generates enough heat to melt the metal. Compressed air is used to remove the molten metal from the cut. The noise is generated when the air disturbs the magnetic field created by the arc which results in a loud crackling sound. The sound pressure level ranges from 108 to 120 dBA. A welder’s personal noise exposure depends on the amount of time spend gouging during their work shift. The highest dose obtained during this study was 483 percent for 10 hour shift.

240 Amps dBA Average 360 Amps dBA Average

Sound Pressure Levels of Various Gouging Rods & Plasma Cutting

Air Arc Technical Noise Study The Sabine Mining Company July 11, 2001

Table 1 List of Materials Gouged or Cut

Table 2 Summary of Q-300 Noise Dosimeter Readings

List of Products and Manufacturers Electra Rod - Rockmount Research & Alloys, Inc. Hypertherm - Plasma - Hypertherm, Inc. Magnum Rod - Magnum Manufacturing, Inc. Cronatron Rod - Cronatron Welding System, Inc. Certanium Rod - CT Engineering Petrogen - Petrogen International, LTD. Carbon Air Arching

Noise Source Identification Project Air Arc Cutting Recommendations (Gouging Alternatives) Based on the data collected, there are alternative methods of performing carbon air arc cutting that will reduce related noise exposures. The information obtained from this study should assist mine operators in choosing products for air arc cutting activities that generate less noise, thereby reducing the noise exposure of miners performing these tasks.

Noise Source Identification Project Air Arc Cutting Recommendations (Bucket Maintenance) Reduce maintenance that may result in the need for air arc cutting on dragline and shovel buckets Changing bucket teeth Improved blasting techniques Minimize backdragging

Noise Source Identification Project Air Arc Cutting Recommendations (Work Practices) Discourage side-by-side air arcing Limit amount of time air arcing