Mining and related Operations (622)

abandoned access africa ancient arizona author bank books break canada canadian capital cave certification chemical coal code companies concern consists content copper corporate crushed deepest deposit depth domestic dust egypt engineering environmental exploration extraction extractive financial flint foundation gas gases global gold gravel health hearing heat impact investment involve iron islands junior lake landfill largest layers lode machinery management map materials mechanical medieval metal metallurgy metals meters mexico mine mined mineral minerals miners mines mining national navigation operations ore oxford pillar pit placer powder practice precious processes processing project prospecting reach reclamation regulation removing republic requires resource retrieved rio rock romans roof safety science sea search sector shaft silver site spain st standards stone stream sustainable tailings technical technique technology tinto ton tools tunnel underground united uranium valuable vein ventilation waste water weapons