Material with no value, called overburden, is deposited by huge dump trucks, capable of hauling over 400 tons of material, over the side of the mine. Consequently the roadways and landscape of the mine'e interior is constantly changing. Ore, called pay-dirt is deposited into a large crusher located inside the mine. From the crusher, ore is sent over a 5-mile conveyor belt system that runs through 3 miles of tunnel to the concentrator where large grinders further pulverized the stone into a fine powder. The concentrator takes the pulverized ore and mixes it into a slurry that is then piped to flotation cells were it is mixed with reagents to produce a bubbly froth. Copper, gold, silver and other metals adhere to the bubbles which is skimmed off and filtered. The resulting concentrate, which contains about 26 percent copper and by-products such as gold and silver, is then sent through a pipeline to the smelter for further processing.