Cyanidation in Heap Leaching

The lixiviation in heap leaching, it has been used since a very long ime ago, both in copper as in uranium, has entered since the decade of the seventies in a massive form, in the treatment of the minerals of gold and silver.

Presently, there exist innumerable plants of this type in the world and its number continues to increase. Its popularity radicates in the minor investment, due to the fact that it does not require a grinder, nor agitation, nor separation of solids and liquids, nor any washing in counter-current, nor very demanding deposits of rewashing.

The basic principles of the lixiviation in heap leaching are very simple: Una solution which contains the lixiviant is watered over a heap leaching of mineral placed in an impermeable portfolio. The rich solution is recollected and the gold and/or silver are recuperated through the technologies available. Even though there is this aparent simplicity, the factors involved are varied and very complex, and many operations fail due to a lack of previous study. Among the recent developments we can find the use of geotextiles for the protection of the impermeable portfolio. Among the favorite methods for carrying the heap leaching, in the present day, are the belts of piling which do not compact the heap leaching and the method of carrying with trucks, but using only a central means for lifting and transiting over the heap leaching. Another recent development is the concept of lixiviation in two stages to better the low recuperation by formation of channeling within the heap leaching. The method consists in that once the first stage is finished the heap leaching is unloaded and it is loaded in the second docket. In this case one will have a system of different channels, allowing a much higher recuperation. When one works with reusable dockets and the lixiviated mineral must go by all means to the ford of a river, this method is advantageous, due to the fact that in the second hep leaching can be of the permanent type. This method is used in the lixiviation of the heap leaching of Borealis in Nevada, United States.