Question

differentiate between open cast mining and shaft mining

Answer 1

Open cast mining

Essentially, overburden is removed, the exposed ore is recovered, and the pit is filled, progressively, by the next tranche of overburden.The working footprint of an opencast mine like Macraes in Otago would typically be up to 300 ha although the total area mined over time would be much greater than that.


Shaft mining 

it is excavating a vertical or near-vertical tunnel from the top down, where there is initially no access to the bottom.All underground mines have some crucial components in common: ventilation shafts to clear toxic fumes from drilling and blasting

Answer 2

Answer:

There are many differences between open cast and underground mining. When minerals and deposits are found close to the surface and spread across a large distance, the best way to mine is to use the open cast mining method. Next the waste rock layer is removed and a pit is dug into the ground to reach the mineral seam.

Explanation:

There are many differences between open cast and underground mining.-

When minerals and deposits are found close to the surface and spread across a large distance, the best way to mine is to use the open cast mining method.

In this process, the area is cleared of all topsoil and vegetation, this material is stockpiled and used later when rehabilitating the area once mining is finished.

Next the waste rock layer is removed and a pit is dug into the ground to reach the mineral seam. A sloping road is created for transporting the unprocessed mineral out of the pit.

Explosives are used to break up the ore which is then scooped into large haul trucks by front end loaders or large electric shovels and transported to a processing plant.

The mineral is extracted from the ore and the material remaining (known as tailings) is deposited in a tailings dam and covered with clay, topsoil and vegetation.

Once the mine has been depleted and all work has been completed, the leftover rock and soil will either be covered with topsoil and revegetated to create new landforms, or it can be used to fill and re-vegetate the pit.