Risks associated with loading pockets
The intensive unloading of ore causes abrasion and impact damage to structures and equipment. Vibrations and corrosion create additional structural problems. The pocket site is generally very grimy, with a lot of dust, mud and water. In most cases, the environment under the pocket is noisy, dark and damp. Some areas are considered to be confined spaces where hazardous materials accumulate. Due to these difficult conditions, it is an absolute necessity to assess risks and to create safety and rescue plans.
During the inspection stage, the loading pocket continues to operate and the train cars that are in the tunnel under the pocket continue to run along the rails. Strict isolation and communication procedures must therefore be followed to access the structures to be inspected.
Since the apron pan feeder internal walls are not visible, engineers can only establish damage estimates for the surfaces and support structures inside the feeder. These estimates will be confirmed and measured using 3D scanning devices when the pan feeder is opened during overhaul.
During shutdown maintenance, the engineer checks and reviews the design efficiently and quickly provide solutions for repairing structures in a timely manner, and often with urgency, in order to reduce the shutdown period to a minimum.
Loading pocket maintenance strategy
The equipment installed in the underground tunnels requires periodic maintenance that should be done during scheduled overhaul periods. Before shutdown, structural engineers should perform a full inspection of the structures connected to the pockets, to evaluate their condition. In particular, they should inspect the apron pan feeder support structures and the access to the tunnel, then provide engineering plans for the restoration work and technical improvements to be carried out during the shutdown period. During construction, engineers are also responsible for providing full on-site support in order to help during the full shutdown and to resolve problems under very tight deadlines. Furthermore, due to changing conditions, the structural engineer must often find alternative technical solutions during the shutdown period.