Mining

Minerals have shaped human history: periods are even named after them, the copper, bronze and iron ages. But large-scale mining really began with the industrial revolution, and it has grown ever since.

Whether a mine is profitable depends on two kinds of factors:

• Physical factors: the size, grade (quality) and mode of occurrence of the deposit (how and where it lies in the rock).
• Economic factors: the demand for the mineral, the technology available, the capital to set up the mine and its infrastructure, and the cost of labour and transport.

There are two main methods.

Surface (open-cast) mining is used for minerals that lie close to the surface. It is the easiest and cheapest method, it is safer, and the output is large and quick.

Underground (shaft) mining is used for ores that lie deep below the surface. Vertical shafts are sunk, and underground galleries spread out from them. It needs lifts, drills, haulage vehicles, and ventilation systems to carry the workers and the ore safely. It is risky: poisonous gases, fires, floods and the caving in of roofs can cause fatal accidents.

Developed countries are retreating from mining, because of its high labour costs, while developing countries depend on mining (which gives jobs and export income) for a large part of their earnings.