In the area of Mining, the activity that gave rise to the company in 1952, OSSA is the Spanish leader in projects for underground works in coal, metal and ornamental stone mining, in the operation of the mine itself and in the development of mining infrastructure. In addition, it handles execution of vertical shafts, access galleries and large-scale caverns for placement of auxiliary services such as tanks, underground workshops, crushing plants and pump rooms.

In doing so, OSSA has relied on the confidence of large mining multinationals, including CODELCO, Southern Perú Copper Co., Río Tinto Minera, Narcea Goldmines, Somincor, Pizarras Expiz, Iberpotash, Hullera Vasco-Leonesa and Hunosa. These companies place OSSA as a solid, reliable partner for the large multinationals at the international level.