Mining

Mining is the process of extracting valuable minerals buried beneath the ground. Evidence of human mining efforts has been found dating back to the beginning of history.

Types of mining

Mining can be either surface mining or sub-surface (underground) mining.

The type of mining further depends on what is being mined. For example, surface mining of coal is strip mining. Surface mining of precious metals such as gold is placer mining. A quarry is an open-pit surface mine for the mining of materials such as slate and gravel.

Sub-surface mining is called hard rock mining if the mining is for hard minerals such as precious metals, and soft rock mining if it is for soft minerals such as coal. Underground mines are also categorized by the direction of entry underground. A drift mine enters the earth horizontally, a slope mine enters the earth at a downward slope, and a shaft mine uses a vertical or steeply inclined downward shaft to enter the mine.

Safety

Dangerous gases such as methane can accumulate in mines and can explode if ignited, and the inhalation of dusts is also a health issue, so underground mines must be ventilated, typically with large fans located above ground which keep air circulating through the mine.

In addition, mines must be inspected for unstable conditions which might result in a cave-in, and other hazardous conditions.