Why are lignite deposits usually mined by surface methods?

Lignite deposits are primarily extracted using surface mining methods because they are typically located close to the surface and often occur in beds of great thickness, sometimes exceeding 30 meters (about 100 feet). These geological characteristics make them easily accessible and allow for low production costs.1

While the choice between surface and underground mining is generally dictated by technological factors—such as the depth of the seam, the nature of the overlying strata, and the thickness of the deposit—lignite’s shallow placement makes surface mining the most efficient and common approach. Conversely, deeper coal deposits or those with unfavorable surface conditions may require underground methods. Because lignite is an inferior fuel compared to higher-rank coals due to its high water content and lower calorific value, the economic efficiency provided by surface mining is essential for its viability.21