Volcan Metallurgy
Prior to 2008, Andina reported positive preliminary metallurgical test results from primary epithermal (sulphide-bearing) gold mineralization from the Volcan Gold Project. Gold recoveries from four column tests of Dorado West deposit mineralization ranged from 57% to 77% with increasing recoveries directly correlated with higher gold grades. The column tests were run for 64 days with the recoveries showing a break out around four days and extraction generally leveling out after 26 days, indicating very fast leach kinetics likely due to the high purity (~98%) and small grain size of the gold.
In May 2008, Andina reported continued positive metallurgical test results from Volcan, following up on earlier metallurgical results. The results from three column tests, along with load tests, further confirm that Volcan's sulphide hosted gold mineralization is amenable to heap leaching.
Column tests completed on two composite samples from the Dorado East deposit achieved gold recoveries of 77%. These results compare favourably with previously reported gold recoveries achieved from column test work completed on similar grade samples from the Dorado West deposit. In addition to the column test work, positive results were obtained from load / permeability tests completed on two samples, therefore confirming permeability of the leached material for simulated heaps up to 40 metres high.
In April 2009 Andina collected additional metallurgical samples from existing stored core. A further set of samples were taken from the stored core in June 2009 and extensive testing continues into 2010. The test work seeks to establish mineral response from various locations and grade ranges that represent the entire mineral resource.