Efficacy of noise control measures at high noise zones from a copper mine in Zambia

Abstract

Introduction: it is estimated that about 30 million workers in the United States of America (USA) and 28% of the workers in Europe are  exposed to high noise levels. In developing countries, occupational noise exposures are limited in the scientific literature due to lack of  research being carried out in this field. We evaluated the efficacy of noise control measures at various sections at Konkola Copper Mine concentrator section in Zambia.

Methods: we used a quantitative cross-sectional study to evaluate the efficacy of noise control measures at various sections of the  concentrator. The study enumerated noise sources, noise release mechanisms and noise controls used. Noise levels without and with  controls at each noise source were also measured using Optimus type1, model CR: 172B sound level meter.

Results: seventeen noise  generating equipment were identified with about 53% of the equipment operated at the crushing section, 18% operated at the flotation and filtration section respectively, and 11% at milling section. A substantial portion (65%) of the identified noise sources in the  concentrator are not housed, and among these, 36% are mobile in nature. It was also found that none of the noise areas were  demarcated. There are three types of noise release mechanism from the 17 machines identified at the sections of the concentrator. Eighty-two percent (82%) of the machines release noise by pulsation mechanism, 12% by jet and 6% by turbulence. Approximately, 76.5%  (13) of the noise controls at the concentrator had efficacy strong enough to reduce noise levels to below the OEL while 23.5% (4) of the  controls had weak efficacy that failed to reduce noise levels to below the OEL.

Conclusion: there is a need to strengthen efficacy in areas  where controls were found to be weak. There is need to sustain controls that were found to be strong to maintain their efficacy. About  75% (3 of the 4) of the controls with lower efficacy were from the crushing section while 25% (1 of the 4) were from the filtration section.