Background
Gold room processes such as acid digestion, calcination, smelting and electrowinning generate fumes, dust and gases that contain hazardous contaminants. Natural ventilation is often ineffective in minimising exposure to hazardous airborne contaminants, and local exhaust (or extraction) ventilation (LEV) systems are commonly used to remove the contaminants generated.
Recent inspections by the Department has identified some gold rooms with inadequate or ineffective LEV systems. In many cases, this has contributed to the exposure of workers to elevated levels of heavy metals (e.g. lead, mercury, inorganic arsenic).
Summary of hazard
Exposure to contaminants, such as heavy metals, ammonia and hydrogen cyanide gases, may lead to a variety of chronic health conditions.
Contributory factors
- Inadequate design and modification of the gold room building.
- Making changes to the process, such as installing new equipment (e.g. larger ovens, furnaces, electrowinning cells), without assessing the efficacy of the LEV system under the new operating conditions.
- Inadequate design and modification of LEV systems which
- do not adequately control the risks associated with contaminants (e.g. fume hood with no extraction fan installed)
- introduce other hazards such as noise and poor ergonomic design.
- Inadequate inspection and maintenance of the LEV system.
- Poor verification of the effectiveness of the LEV system, through inadequate:
- performance monitoring (e.g. air velocity, static pressure)
- biological and atmospheric monitoring.