Del Carmen Metallurgy
The results from preliminary metallurgical testing (bottle roll) released in January 2011 show average gold recoveries of 76.5% for five Del Carmen Norte samples (three from Rojo Grande, two from Naciente Quebrada Pedregosa). Overall, the test results indicate good potential for both heap leach cyanidation treatment and for whole ore milling/cyanidation treatment of the materials represented by the five composite samples tested.
The above quoted recoveries are for material crushed to 6.3 millimetres (mm). Four of five 6.3 mm samples range from 78.3% to 83.1% gold recovery while the fifth sample showed 61.4% recovery. Silver recoveries ranged from 15% to 65% for those samples with detectable silver (four of five) and were generally higher for milled compared to crushed material. Importantly, cyanide consumption was low with a reported average for all samples of 0.16 kg/t. See full report for more details.
Phase 2 metallurgical testing is is underway, using material from holes completed in the 2010/2011 drill season. Sample selection and collection of seven composites from Rojo Grande was completed in October 2011 and over 1,400 kilograms sent to the McClelland Lab for testing. The program consists principally of column leach tests to evaluate the amenability, feed size sensitivity and variability of Rojo Grande ores (four composites from silicification, three from quartz-alunite alteration) to heap leach processing. The lab will also complete additional bottle roll tests, petrographic characterization (gold deportment) of the ore, load and permeability tests and evaluation of the acid generating characteristics of the leached residues. The results are expected in mid-2012 and the metallurgical testing is anticipated to be sufficient to support a future Preliminary Economic Assessment of the Rojo Grande deposit.
