Technical Report for the Maricunga Gold Mine - Kinross Gold

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Kinross Gold CorporationMaricunga Mine Technical Report16.2 Metallurgical Test Work 200616.2.1 IntroductionGold recovery rates for the Verde and Pancho deposits have been estimated from test workconducted at McClelland Laboratories in Reno, Nevada. In 2003, a total of 9 column leachtests were done on 7 Pancho composite samples and 11 column leach tests were done on11 Verde composite samples. In 2006, an exploration drill program on the Pancho propertyprovided samples for an additional 14 column leach tests at McClelland. Final test data wasavailable by August 2007 and these gold recoveries have been integrated in the Panchoreserve estimate.16.2.2 Comments on Historical Metallurgical Composite Selection CriteriaThe early work on Maricunga metallurgical type classification established that the mostpredominant metallurgical criteria were grade, oxide state and crush size. The 1998metallurgical column testing relied on the classification of four groups of sample types largelypredicated by the amount of sheeted and stockwork veining as well as silicification. The fourgroups are outlined below.• Group 1 – 81.4% recovery – Strong sheeted veining, moderate strong stockwork,and weak matrix silicification.• Group 2 – 72.9% recovery – Moderate-strong sheeted veining, moderate stockwork,weak matrix silicification.• Group 3 – 66.1% recovery – Weak-moderate sheeted veining, weak stockwork, andweak to moderate matrix silicification.• Group 4 – 50.4% recovery – Weak-nil sheeted veining, weak-nil stockwork, andmoderate strong silicification.These groupings were specific to Verde, where East Verde was predominantly representedby Group 2, while West Verde was mostly comprised of Group 3.In 2003, the methodology for metallurgical sample selection was changed. Of concern wasthe issue that the head grades of the group 1 to 4 samples were 20 to 40% above averagegrade of the deposit and it was suspected that higher grade column samples would result inhigher gold recoveries. In addition, field geologists had concerns with the classification of66
Kinross Gold CorporationMaricunga Mine Technical Reportsilicification and the ability to differentiate between stockwork versus sheeted veining inchips from the predominantly RC based database.As a result of the assessment of the Maricunga database and regression results and historicresults, it was proposed to classify metallurgical column test samples, firstly by oxidationintensity, then by grade, and by elevation where appropriate. Due to questions of databasesuitability and analysis, a lower priority was given to veining, silicification, argillic alterationand lithology.In 2003, before the final composites were selected for column tests, McClelland Laboratoriesin Reno completed bottle roll tests on 14 Pancho “point samples” selected to represent thelikely metallurgical domains. Samples were differentiated by grade, lithology and oxidationstate and subjected to a 96 hour bottle roll leach at a crush size of 80% passing 1.7 mm.The results showed that the oxidation state is the only reliable predictor of heap leach goldrecovery. Head grade and lithology do not significantly affect gold recovery. This correlationwas borne out in the column tests and the current Pancho mine plan uses gold recoveryvalues based only on oxide, mixed and sulphide ore designations.16.2.3 Metallurgical Composite Selection Criteria (2006)In 2006, an extensive drill campaign was completed on the Pancho deposit and drill corecomposite samples were shipped to McClelland Laboratories in Reno for metallurgical testwork. The first stage of test work was to complete seven column tests on Pancho drill corecomposite samples crushed to 80% passing 6.3 mm. The objective was to test thevariability of gold recoveries from ore in zones of the Pancho pit that had not been testedpreviously. Composites were selected from single holes where possible to maintain thespatial integrity of the sample. The McClelland columns were 6" diameter x 10' tall and held68 kg of rock. The column tests were run at a crush size of 80% passing 6.3 mm in order tobe compatible with the previous test work completed on the Verde deposit.The second stage of test work was to select a typical sulphide sample and a typical oxidesample from a multi-hole composite and conduct a crush size variability study to determinethe effect of particle size on gold recovery. Crush sizes of 6.3 mm, 10mm and 16 mm wereselected. The oxide column leach tests have only just begun and no data is available yet. In67
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Technical Report for the Maricunga Gold Mine - Kinross Gold

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