Hard Rock Gold Mining Processes Yemen – Rock Ore Crusher. Hard Rock Mining Gold and Silver Ore and Interested in hard rock gold and silver ores and how they are processed Most of the gold and silver produced comes from hard rock gold mining methods.The hard rock crushing capacity is usually nothing less than 10 tonnes of hard rock per hour. Such rock crushing capacity gives the opportunity to produce even several hundreds of pure grams of gold per day if not half a kilogram or kilogram of gold. As a primary crusher, after the jaw crusher one need to use the rock milling machines.