Question

Difference between underground mining and surface mining in tabular form

Answer 1

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Main Difference

In surface mining, the ore is accessed directly from the Earth's surface, and contact is maintained with the surface throughout the operation.

Underground or subsurface mining is accomplished with the help of tunnels going into the Earth, and does not occur on the surface.


Working Principle

In surface mining, the topsoil and bedrock is removed to access the ore; all done from the surface.

In underground mining, the bedrock is kept intact, and tunnels are used to access the ore from below.


Type of Ore

Surface mining is suitable for large, low-grade ore deposits which occur below a thin layer of rock, or alluvial deposits found in sand and riverbeds.

Underground mining is used for small, high-grade deposits covered with a thick overburden (soil and rock above the ore), or for deep and sloping deposits.


General Process

In all method of surface mining , first, the overburden is stripped off using earthmovers. Then, bucket-wheel excavators remove the ore, which is loaded into haul trucks with shovel loaders. When the deposit is exhausted, the overburden is refilled in the crater, and the land is restored with the local vegetation.

In most Underground mining methods, deep vertical tunnels called shafts are drilled into the ground, along with a set of horizontal tunnels called drifts from the shaft bottom to access the ore. Then, longwall and continuous miners break up the ore deposit, which is transported back to the surface by conveyors.