11. The heap leaching operations provided 4, 148 ounces. 12. In 1987 Carpentaria Gold Ltd opened a new open cut mine using modern heap leaching processes. 13. Thus, a unique feature of nickel heap leaching is the need for a tailings disposal area. 14. Almost all the gold in Nevada comes from large open pit mining and with heap leaching recovery. 15. The expansion is for heap leaching , a process in which acid is filtered through piles of copper ore. 16. Iron pyrite was heaped up and allowed to weather ( an example of an early form of heap leaching ). 17. Although the heap leaching is a low cost-process, it normally has recovery rates of 60-70 %, although there are exceptions. 18. Once the ore is mined it can be treated as a whole ore using a dump leaching or heap leaching processes. 19. Small amounts of uranium were also produced by underground in-situ leaching and heap leaching of low grade ore and even waste rock. 20. The method known as heap leaching was first proposed in 1969 by the US'Bureau of Mines, and was in use by the 1970s.
