Implementation of the Pilot Plant

As it was already previously mentioned, the run test of laboratory have demonstrated the lixiviability of the mineral by using diluted sollutions of cyanide, for which it was considered to put to use scale pilot tests at a level of heap leaching.

 The adoption of this technique (heap leaching) was conditioned to the characteristics of the mineral, having been determined in a practical form the following favorable conditions:

• High cynetic of extraction of gold, which has been favored by the size of the mineral and the natural porosity of the same.
• Absence of the elements known as cyanicides.
• Low levels of carbonaceous material, which can assure the no premature adsorption of gold over these materials.
• Good characteristics of percolation even though it contains considerable amounts of fine material.

The heap leaching was built on a field located near to the central pike and over a base appropriately prepared. The distance for transporting the mineral from the mineralized body until the heap leaching is of 300 m.

The recuperations of gold are in the order of 80%, a level which can be considered acceptable, even though repeated tests have reported higher recuperations.

Base Preparation
The success of the operation very much depends in the attention which is given to the operation of the base; as a matter of fact, it is a fundamental factor to count with a base which is completely impermeable to the circulating solutions and that, besides, one can count with the adequate pendent so that the impregnated solution be collected in a point from which it afterwards will be conducted to the tank of impregnated solution.

 The main steps to be followed for the preparation of the base are indicated in detail as follows:

• The surface was compacted fulfilling the necessary specifications of engineering. The behavior was effectuated using a roller, making use of water when it were necessary.
• The appropriately compacted surface was covered with a layer of guide clay in a thickness of 12 cm. The roller and the water were used for dampening and compacting.
• In the compacted area a plastic cloth and yute were extended to make sure that the solution will not be lost by filtrations.
• It was covered with a second layer of guide clay in a thickness of 12 cm. and was compacted afterwards.
• In the extremes of the prepared base the canals were constructed with the intention of getting the impregnated solution which can drain towards the lateral sides of the heap leaching.

Once this sequence is fulfilled, the next step corresponded to the loading of the mineral. To the present date, the base has shown excellent results, due to the fact that the balances of circulating solution does not show loss of solution by filtrations of the base.