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Cut-and-fill Stoping

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Mining Processes

Cut-and-fill stoping is a method of underground mining used in vertical stopes and in mining high-grade irregular ore bodies. The rock mass surrounding the ore deposit is also usually weak—unable to support loads over an extended stoping height.[1] As the name of the method implies, successive cutting of the ore into horizontal slices is carried out starting from the bottom of the stope and progressing upwards towards the surface. This horizontal slicing leaves a void that is backfilled with material to provide support until all the ore is extracted from the mine.

[edit] Process

In a cut-and-fill stoping operation, ramps or inclined tunnels are excavated to connect the surface to the underground ore body. Drifts are excavated to access the ore; chute raises are excavated to provide the easy removal of ore from the mine.

Drilling is the first stage in removing slices or ore using a mounted pneumatic or rotary percussion jumbo drill. A secondary stage involves blasting the ore to further break it up. Blasting is typically carried out using one or a combination of ammonium nitrate and fuel oil (ANFO), slurries, and emulsions. Bulk blasting methods may also be used. In some circumstances, a mechanism for secondary breakage of the ore is necessary and the drill-and-blast method, mudcapping, or impact hammers are used to accomplish this.[2] It is common to remove horizontal slices of ore that span the entire width and length of the stope.[3]

Mucking of ore is accomplished with a wheel loader, front end loader, or motor scraper that pushes the mucked ore to a mill hole and chute connected to a haulage passage underneath.[4] The ore is then hauled away in dump trucks, load haul dump trucks (LHDs), and scoop trams to a lower elevation within the mine and then transported up to the surface via a ramp by a scoop tram or a load haul dump.[5]

Once a slice of ore has been completely mined from the stope, the empty space left behind is backfilled hydraulically. Sometimes ore waste is mixed with other materials such as sand, cement, waste rock, or dewatered mill tailings—a low-grade ore that has been rejected for processing—to make the backfill.[6] Backfill provides a working floor for miners and equipment as the mining progresses and also supports the stope walls.

[edit] Equipment Used

[edit] References

  1. Cut and Fill Stoping. Mining Basics. 2008-10-07.
  2. Hartman, L. Howard and Mutmansky, M. Jan. Introductory Mining Engineering. John Wiley and Sons, 2002. 364
  3. Cut and Fill Stoping. BC Minerals. 2008-10-07.
  4. Cut and Fill Stoping Mining. Mining Basics. 2008-10-07.
  5. Cut and Fill Stoping. BC Minerals. 2008-10-07.
  6. Cut and Fill Stoping. BC Minerals. 2008-10-07.