Attenuation of ear muffs in Canadian mines

Abstract In Canadian mines, ear muffs are now an essential part of safety equipment. Because of this, a research study was conducted to investigate their efficiency. The main characteristics of eleven commercially available ear muffs were investigated in the laboratory and analyzed by: (1) a psychophysical method; and (2) a physical method. These investigations showed the following effects:head size has a significant influence on the attenuation because of a different clamping force;the amount of hair trapped between the ear muff cushion and the head decreased ear muff attenuation; attenuation and comfort are not in a causal relationship;with the use of glasses and their adapters, attenuation decreases—the adapters are not effective sound barriers;there are no great differences in attenuation with neck movement; the efficiencies of various brands of ear muffs are not equal; ear muffs with a small cushion area start serving   their purpose   more   quickly because the force per unit area is larger; a clamping force larger than 900 g wt, in most ear muffs, does not cause an increase in attenuation; attenuation   characteristics   (ANSI Z24.22 - 1957) of ear muffs show some correlation with physical tests.Nine ear muffs out of the eleven were tested under uniform conditions in mines. Three ear muffs were found to be the best. All three ear muffs have bands passing behind the head. The ear muff with a support strap, which improves comfort and maintains a good fit during wear, showed the best attenuation. Causes of poor attenuation are numerous: bad mounting of ear muffs on helmets, improper fitting, interferen-cy by hair and glasses, improper wearing by miners, unsatisfactory enforcement by supervisory personnel, incomplete training of miners, etc.Results of this research have indicated that none of the ear muffs tested in this study contain all of the characteristics desirable in an ideal unit.Because of unsatisfactory ear muff attenuation in working conditions (15 dBA), it should be a mandatory requirement that workers wear both ear muffs and ear plugs if the noise level is higher than 105 dBA (various literature recommends 110 dBA).The key to the solution lies in the following:the foreman must be capable of helping and controlling miners in their task of wearing ear muffs properly; the program  must be  introduced to miners; and constant contact must be maintained with manufacturers.
Keywords: Underground mining, Ear muffs, Safety, Mine safety, Noise control, Attenuation.
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Summary: This paper describes the rejuvenation of a molybdenum mine-mill complex at the head of Alice Arm, 500 miles north of Vancouver and 85 miles north of Prince Rupert, British Columbia. It includes a description of the property history of the deposits and of the previous operations, together with details of the project for re-opening the mine.
Publication: CIM Bulletin
Author(s): C.A. BORN, W.D. LENTON
Keywords: Kitsault Project, Open-pit mining, Molybdenum deposits, Coast Range, Project development, Equipment, Milling, Tailings disposal.
Issue: 812
Volume: 72
Year: 1979
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Summary: The paper examines the problems that arise in undertaking socio-economic impact studies to meet the requirements of environmental-impact legislation governing new mine development or expansion. An approach to undertaking socio-economic impact studies is outlined, responses to specific problems are discussed and ways in which the mining company can use these studies to meet its general objectives are explored.The paper concludes by examining how a socio-economic study, as required by legislati...
Publication: CIM Bulletin
Author(s): WILLIAM E. STANLEY, JOHN E.L FARROW
Keywords: Environmental control, Socio-economic studies, Resource development, Legislation, Approvals, Governments, Mining projects.
Issue: 812
Volume: 72
Year: 1979
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Summary: The Westinghouse Templifier™, using heat pump principles, recovers low-grade waste heat in the 60°F to 160°F temperature range and amplifies it to usable levels of up to 220°F. Coefficients of performance (C.P.O.) normally encountered are from 3.0 to 6.0, with capacities from 200,000 to 10 million Btu/hr.
Publication: CIM Bulletin
Author(s): RON FERRIS
Keywords: Equipment, Maintenance, Heat pumps, Templifier, Heating, Energy conservation.
Issue: 812
Volume: 72
Year: 1979
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Summary: Service failures of seemingly conventional galvanized bolts, in normal operation, on transmission towers in New Brunswick have been found to be the result of hydrogen cracking. In both these cases, similar failures elsewhere can be avoided by suitable clauses in the purchase specifications.In the first case described, the manufacturing procedure was responsible for strengthening and embrittling a standard, soft, constructional steel. In this case, a fracture mechanics analysis predicted...
Publication: CIM Bulletin
Author(s): J.C. THORNLEY
Keywords: Cracking, Hydrogen cracking, Fracturing, Steels, Galvanized steel, Bolts, Transmission towers, Corrosion.
Issue: 812
Volume: 72
Year: 1979
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Summary: The correct application of large crater blasts in unfrozen tar sand is an effective means of resisting frost penetration during winter. This results in much higher productivity and considerably less down time with excavators during winter operations. The resulting flatter angle of repose of the highwall has readily been accommodated with slight modification to bucket-wheel excavator operating procedure.Other mining schemes call for large draglines to be located on top of the highwall, which...
Publication: CIM Bulletin
Author(s): A. BAUER, W.A. CROSBY
Keywords: Mining methods, Open-pit mining, Blasting, Slope stability, Tar sands, Crater blasting, Draglines.
Issue: 812
Volume: 72
Year: 1979
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Summary: Shebandowan Mine presents a unique opportunity for the mining industry to demonstrate its willingness and ability to use electrical energy effectively. The mine is a typical 2500-ton/day operation supplied by a 15-MVA power transformer. It is a recent, up-to-date design and operates on a four-day/week, two-shift/day basis.The paper outlines an energy profile based on historical data. It accurately describes the individual and total energy input for:(1) production and non-productive functions;...
Publication: CIM Bulletin
Author(s): JOSEPH H. HARRIS, T.B. ARMSTRONG
Keywords: Energy conservation, Electrical energy, Inco Metals Co., Shebandowan Mine, Control Systems.
Issue: 812
Volume: 72
Year: 1979
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Summary: The decay of 222Rn yields a series of short-lived decay products which become attached to the surface of opiate or wire exposed in a 222Rn-bearing atmosphere. The alpha-activity of two of the decay products, 2l8Po and 2I4Po, can be measured by simple counting techniques. This phenomenon may have direct application to uranium exploration.Laboratory studies have shown that:(a) radon decay products can be collected on a wide variety of materials (including various kinds of metals and plastics);(...
Publication: CIM Bulletin
Author(s): JEFFREY W. CARD, KEITH BELL
Keywords: Exploration, Uranium exploration, Radon, Decay products, South March deposit, Radium, Soils.
Issue: 812
Volume: 72
Year: 1979
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Summary: Is there a relationship among the Sudbury nickel ores, the Cobalt deposits, and the Huronian, Athabascan and North Australian uranium provinces?All are within intracratonic basins, with ore near basal unconformities. There are similarities in the geochemical "fingerprints" pointing to basic igneous rock affiliations. Some show a time relationship to basic igneous activity and to great rift systems. Many basic dykes show radioactivity at their edges. A spatial relationship between...
Publication: CIM Bulletin
Author(s): C.J. SULLIVAN
Keywords: Geology, Mining history, Intracratonic basins, Ore deposits, Uranium deposits, Athabasca Basin, Alligator River deposits, Sudbury Basin, Cobalt, Blind River, Exploration, Kom-bolgie Basin, Huronian Basin, Aggressive deposit, Jabiluka deposit.
Issue: 812
Volume: 72
Year: 1979
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Summary: There is an increasing awareness on an international level of the potential for utilizing many wastes and by-products as construction materials. This has resulted in recent major reviews by OECD and RILEM to supplement national activities by agencies such as CANMET, USBM, BRE and LCPC. Much of this international and national work was reported during an International Conference on the use of by-products and wastes in civil engineering held in November 1978 in Paris.Based on participation in...
Publication: CIM Bulletin
Author(s): J.J. EMERY
Keywords: Industrial minerals, Wastes, By-products, Construction materials, Slags, Asphaltic concrete, Sulphur, Environmental control.
Issue: 812
Volume: 72
Year: 1979
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