Lesson 7.3: Mechanical Surface Mining Methods - Open Cast Mining & Related Methods

Lesson 7.3: Mechanical Surface Mining Methods - Open Cast Mining & Related Methods

Open Cast Mining

Open cast mining is usually associated with coal or other tabular deposits that are more or less flat-lying. A significant difference between open pit and open cast mining methods is that in open cast mining, overburden that is removed to gain access to the ore is immediately placed in the previously mined cut. Therefore, reclamation occurs concurrently with other mining activities.

Two major sub-methods within open cast mining are area mining and contour mining. If the topography is relatively flat as illustrated in the left figure, then area mining is appropriate. If the terrain is hilly or mountainous as indicated by the figure on the right, then contour mining is indicated.

The reason that different methods need to be used depending on the terrain will become clearer as we look at them in more detail. Area mining is able to use much larger equipment, and as such will generally have lower stripping and mining costs. However, this large equipment requires a flat-lying topography to operate. Contour mining, on the other hand, is well suited to mining around the mountainsides, but uses smaller and different equipment; and, accordingly, we lose an economy of scale that we have with area mining. Nonetheless, it is an important and viable method to recover coal deposits. Let’s take a look at each sub-method in more detail.