Structural Expertise in Ore Loading Pockets

2 July, 2019 | Blog

XING LI, P.Eng.

Practice Leader - Civil, Structural and Geotechnical

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CELINE SIMARD, Eng., M.Eng.

Executive Director Practice

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Ore loading pockets are used at strip mining operation sites. They generally comprise a dumping station, the top of which is equipped with a protective bumper, a dumping tunnel dug into the rock itself, and an apron pan feeder installed at the bottom of the tunnel.

Trucks unload the crude ore into the pit, which feeds the material into an apron pan feeder at the bottom of the loading pocket. This controls the flow of ore and transfers it into train cars that transport the raw material to the crusher, by train or an equivalent means of transportation, which may collect the ore from multiple loading pockets.

 

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.

How BBA can help you

Our teams can help you during pre-commissioning verification, for applying insurance and quality control protocols, and during commissioning.

Our achievements highlight our expertise and our deep knowledge of these facilities. Despite many challenges, a difficult underground environment and very tight deadlines, our teams have managed to reduce shutdown periods for refurbishment, while updating various systems in order to increase reliability and production capacity. Significant improvements have also been made to safety. Our teams have proved their dedication, resourcefulness and ingenuity for the year-long preparation for the shutdown.

Our structural specialists can answer all your questions about our inspection, engineering or facility shutdown services, and help you to meet the challenges associated with ore loading pockets.

 

BBA expertise in loading pocket structures

  • Inspection of all loading pocket structures.
  • Restoration of the support structures connected to the loading pocket.
  • Repair or replacement of foundations, if needed.
  • A solution aimed at reducing the duration of the shutdown needed for the overhaul (e.g. bolted splices instead of welded splices).
  • Safety improvements for the access to work areas.
  • Technical support during shutdown.

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