Fatality caused by concrete crushing plant
Background
In a recent incident, a worker suffered fatal injuries while removing an item from the jaw crusher of a concrete crushing plant. The worker had attempted to remove the lodged item, and was fatally struck when it became free.
Non-crushable items pose a serious risk when using concrete crushing plant. When these items enter the feed chute of the crusher, they create stored energy which can cause the item to be expelled.
Photo 1 depicts Terex Pegson XA400 Concrete crushing plant
Safety Issues
Guidance should be sought from the manufacturer’s manual relating to the correct process for clearing a non-crushable item from a jaw crusher. This should be completed in conjunction with a risk assessment specifically related to this task. Businesses must consider appropriate controls to manage the risk to workers.
Plant isolation must be considered, including the potential for component movement even when the plant is not operating. Ensuring correct guarding is fitted and exclusion zones are adhered to as per manufacturers recommendations.
Consideration must also be given to the potential for stored energy to be created within the plant, and the possibility of the unexpected release of this even when the plant is isolated.
Later models of jaw crushers include features that prohibit the bridging or stalling of the jaws through the sensing of non-crushable items. This eliminates a stall event, and the creation of stored energy in the moving parts.
View the below video to see how the system works.
Photo 2 depicts cross-section of the jaw crusher without overload cylinder
Photo 3 depicts side view showing overload release cylinder
Action required
Business owners and managers must ensure the health and safety of workers and other persons who may be affected by managing, minimising or eliminating the risks.
In conducting a risk assessment, businesses must identify hazards, select, and implement control measures using the hierarchy of control, maintain and review controls, to ensure these remain effective. Specifically, consultation with manufacturers and suppliers to identify the approved process for unblocking a stalled crusher, should be considered.
Further details on the risk management process can be found in the How to manage work health and safety risks Code of Practice 2021 (PDF, 0.65 MB).
The process of crushing materials should involve a pre-screening to ensure incompatible materials are not introduced into the process.
A safe system of work should be developed in the instance a non-crushable item becomes lodged in the plant working parts. The system should cover:
- Correct plant isolation procedure.
- Identification and assessment of potential stored energy areas.
- Release of stored energy in accordance with manufacturers recommendations.
- Safe worker location while undertaking dislodgement procedure (i.e. not being located above the hopper or in a location where the ejected obstruction could drop).
- Potential for item to be dislodged entirely from machine footprint.
- Correct guarding is fitted and in working order.
- Work area assessment for non-crushable items.
- Checking for the available manufacturer’s recommendations included in the maintenance manual.
Businesses may also find information on stalled crushers and removing blockages within Managing the risks of plant in the workplace Code of Practice 2021 (PDF, 1.57 MB).
Further information
Further information can be obtained from the following: