History of Mining Equipment & Practices
2017-4-11 · In 1914 a contract was let for removing 8,000,000 cubic yards of stripping at the rate of 2,000,000 cubic yards per year to uncover 6,000,000 tons of ore for open-pit mining. It was contemplated that later work would require the additional removal of 14,000,000 cubic yards of overburden to make available for mining …