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Engineering Controls Database

Reductions of Blood Lead Levels in Lead Smelter Workers

Trucks loaded with used batteries arrive at the plant battery breaking area to be unloaded. The batteries are removed from the trucks by hand and placed on a roller conveyor which feeds batteries to the battery puncher. The battery puncher punches holes in the battery bottom to drain out the electrolyte. Batteries are then automatically crushed and shredded. The crushed and shredded pieces go to a flotation separator where lead, plastic, and hard rubber are separated. The wet lead-bearing material is conveyed to a kiln and dried. The dried lead is conveyed to a reverbatory furnace and melted into elemental lead. Slag drains out of the furnace into the molds. The molds are cooled with water and dried. The slag is then fed to the electric arc furnace in which lead is trapped off and sent to refinery pots. The elemental lead is poured into the refinery pots. Caustic soda, nitrate of soda, powdered sulfur, and red phosphorus are used to treat lead in the refinery process. Lead is then agitated, skimmed, and drossed. The lead is next alloyed, poured into pigs, bound, and stored until shipment.
Lead in a body’s system targets the Central Nervous System, the Peripheral Nervous System, the kidneys, and the hematopoietic (blood forming) system. Lead exposure can lead to muscle weakness known as “wrist drop,” Anemia, proximal kidney tubule damage, chronic kidney disease, elevated blood pressure, fetal damage in pregnant women.
Several types of controls were implemented to reduce blood lead levels in the workers. First, engineering measures which includes substitution, process and equipment modification, isolation and automation, and local and general ventilation. Work practices that were enforced were personal hygiene practices, housekeeping, and worker rotation to low exposure areas. Personal protective equipment – respirators, gloves, goggles, and aprons – were used.

Primary controls used: Local exhaust ventilation, partial enclosures, and enclosed ventilation in reverbatory furnace operations, electric arc furnace operations, and casting and refinery area; HEPA-filtered half-mask and full-face negative pressure respirators and full-face and PAPR respirators worn in production areas of plant
Unique controls: Financial incentives in the form of bonuses; strict policies of personal hygiene; paved parking lots and around buildings to keep dust to a minimum; frequent use of wet sweepers to control dust which contained small amounts of lead.

List of 12 different engineering controls used:
Kettle hooding
Expand baghouse capacity
Automatic dross skimmer
Improve furnace hooding
Increase baghouse ventilation
Improve refinery ducting
Increase general ventilation
Surface parking lot
Expand baghouse by 20%
New wet sweeper
Automatic battery dumper
Improve kettle hooding
243-05-A; 243-05-B; 243-05-C;
automatic batter dumper
automatic dross skimmer
battery wrecker
battery wrecker operator
lead smelter worker
lead smelting
reverbatory furnace
secondary lead smelting
smelter baghouse
Estimated Effectiveness and Ranking of Engineering controls and incentive program:

1. Wet sweeper (high): 29.7%
2. Automatic battery dumper (high): 27.0%
3. Expand smelter baghouse (high): 23.5%
4. Wet sweeper (low): 22.7%
5. Surface parking lot (low): 21.1%
6. Wet sweeper (mod): 21.0%
7. Bonus 29 (high): 20.1%
8. Surface parking lot (high): 19.6%
9. Bonus 34 (low): 18.9%
10. Improve hooding on furnace: 16.7%
11. Bonus 39 (low): 15.8%
12. Bonus 29 (low): 15.6%
13. Expand smelter baghouse (mod): 15.0%
14. Three 1990 engineering controls: 13.1%
15. Bonus 34 (high):12.5%
16. Bonus 39 (high): 12.2%
17. Surface Parking lot (mod): 11.4%
18. Bonus 29 (mod): 11.3%
19. Automatic Battery Dumper (mod): 11.2%
20. Improve Refinery Air Circulation: 9.8%
21. Bonus 34 (mod): 8.7%
22. Expand Furnace Baghouse: 8.0%
23. Bonus 39 (mod): 6.9%
24. Automatic Dross skimmer: 1.7%
25. Bonus 24 (high): 0.4%