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Environmental phase, Bunker Hill Study, Bunker Hill Company, Kellogg, Idaho.

Cassady ME; Larsen LB
Cincinnati, OH: U.S. Department of Health, Education, and Welfare, Public Health Service, Centers for Disease Control, National Institute for Occupational Safety and Health, IWS 56-10.5, 1976 Jan; :1-176
This report contains information of findings of industrial hygiene surveys conducted at the Bunker Hill Company lead smelter and zinc plant during October, 1975. The report also contains information from a review of the literature conducted upon receipt of the health hazard evaluation request. Results of medical examinations are being tabulated and evaluated. Upon completion of this study, a determination will be made whether substances normally used as found in the work place are potentially toxic in such concentrations used or found. The following are general recommendations on approaches which have been utilized and are considered to be good practices in mining and smelting operations for the effective control of dust and fume exposures. For the specific methods and design which would be successful in Bunker Hill's operation it will be necessary for a staff engineer or consultant experienced in ventilation design to evaluate the needs. The existing ventilation systems should be evaluated for effectiveness. Many systems are poorly designed and/or poorly maintained. 1. Transition places should have a slope no greater than 12 degrees included angle. Transition pieces observed during the study in the crusher (High Line - Lead Smelter) went from 24" or 36" duct into a 48" duct directly with no tapered transition. 2. No two branches should enter a main directly opposite each other. One main header was observed having 5 or 6 branches entering at about the same location. 3. A branch should enter a main at no greater angle than 45 degrees. In some instances in the lead smelter, branches entered mains at 90 degrees. 4. Abrupt changes in directions of gas flow will result in wearing at that point and also plugging. 5. Exhaust points at material drops should have at least two belt widths ahead of the drop, or placed on an enclosure sufficiently high to prevent material from bouncing into the high velocity air stream. 6. Conveyor enclosure heights should be a minimum of 3/4 belt width off the conveyer to provide sufficient particulate settling capacity. 7. If at all possible, to reduce piston or bellows action as the material drops onto conveyor belts and properly to protect the belt, "dead beds" or "rock boxes", the width of the material flow should be installed. "V" plates should follow the dead bed to provide an air space on both sides of the conveyor enclosure as well as to center the load. The length of the "V" plate will depend on the material volume and belt speed. It should, however, be sufficiently long to insure material pass-through before reaching the end of the plate. 8. As material drops onto conveyors, to abate further escapement of material from under the enclosures, adjustable angular rubber skirts should be installed. Also, fitted rubber curtains should be installed at the entrance and exist of all conveyors enclosures. 9. Inspection ports for hoods at conveyor transfer points were left open and doors were observed to be missing or replaced by a large mesh screen all of which reduces the effectiveness of the system and should be corrected accordingly. 10. Repair of local exhaust systems is required as most were observed to be in a very poor state of disrepair.
Industrial-environment; Field-Study; Smelters; Smelting; Lead-compounds; Lead-dust; Lead-fumes; Lead-smelting; Zinc-compounds; Exposure-assessment; Exposure-levels; Exposure-limits; Region-10; Health-hazards; Health-surveys; Heavy-metals; Electrolytic-refining; Dust-control; Dust-exposure; Fumes; Dusts; Ventilation-systems; Ventilation-equipment; Acid-mists
7439-92-1; 7440-66-6; 7446-09-5; 10102-44-0; 1314-13-2; 7440-36-0; 7439-96-5; 7440-43-9; 7664-93-9; 7440-38-2; 7440-48-4; 7440-02-0; 7784-42-1; 7440-50-8
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Field Studies; Industry Wide
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National Institute for Occupational Safety and Health
Page last reviewed: September 11, 2020
Content source: National Institute for Occupational Safety and Health Education and Information Division