مفتوحة مفتوحة الألغام حفرة مفتوحة يلقي قطع مفتوحة
تعدين الفحم حفرة مفتوحة chipeproject Coal mining Wikipedia. Coal mining is the process of extracting coal from the ground. Coal is valued for its energy However, there are open pit mining operations working on coal seams up to 1,000–1,500 feet (300–460 .