What are the differences between open pit mining, underground mining, and strip mining?

Acid mine drainage occurs when water molecules infiltrate the spoil banks. The water reacts with sulfide minerals to produce sulfuric acid, which then contaminates streams, impoundments, and groundwater resources. Strip mining, also known as surface mining, is the process of stripping off surface soil and rock in order to reach the mineral of concern.

About 90 billion metric tons of coal are potentially available for strip mining within 50 meters of the ground level; 40 billion metric tons of coal are accessible by surface mining techniques in the USA.

Underground mining is done underground. It is dangerous for mine workers. For example, an underground mining accident in Turkey two years ago (almost three years ago) claimed the lives of 310 workers. There are always risks of collapse, explosion, and fire in such operations. Some illnesses are common in miners.

Land subsidence may occur over mines; coal fires in underground mines may result in diseases and ecological harm; acid mine drainage from mines and waste piles may contaminate many kilometers of streams and rivers.

Open pit mining involves digging a large open pit to extract minerals or ores. Underground mining involves digging tunnels or shafts to access underground resources. Strip mining involves removing layers of soil and rock to expose the desired resource, usually coal or oil sands. Each method has different environmental impacts and costs associated with it.