Technical Report for the Maricunga Gold Mine - Kinross Gold

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Kinross Gold CorporationMaricunga Mine Technical Reportevaluate crush size sensitivity of the Pancho ore. Gold recovery increased incrementally (3%- 6%), by crushing from 15.9mm to 9.5mm in size. Gold recoveries obtained from bothcomposites were essentially the same at the 9.5mm and 6.3mm feed sizes.Column test gold recovery rates for the 2240, Pancho 6, CCT and Oxide composites wererapid, and gold extraction was substantially complete in about 25 days of leaching. Goldrecovery rates were slower, and gold extraction progressed at a slow, but significant rateafter 75 days of leaching, for the 1690, 1840, 1930 and 2140 composites. The slowest goldrecovery rates observed were for the 1840 Shallow and RHEVC composites.Column test cyanide consumptions generally were high, but were not as strongly correlatedto copper head grade, as seen during bottle roll testing. Column test cyanide consumptionstended to increase with increasing leach solution application, as normally expected forcolumn leach tests. Because some of the column test leach cycles were relatively long induration (>140 days), the resulting cyanide consumptions were relatively high. Averagecolumn test cyanide consumption (6.3mm feeds) was 2.39 kg NaCN/mt ore.Column test lime additions were made based on corresponding bottle roll test limerequirement data. Lime requirements for the drill core composites varied substantially. Initialcolumn test lime additions ranged from 1.8 to 13.0 kg/mt ore. Those lime additions weresufficient for maintaining protective alkalinity during leaching, for most of the composites.Minor pH control problems were encountered during leaching of the 2140 and 2240composites, and relatively small lime additions were made to the column test barrensolutions during leaching, to help control leaching pH. Severe pH control problems wereencountered during leaching of the Oxide and CCT composites, and the lime added duringleaching for pH control was equivalent to more than the lime added to the ore initially. Thehighest observed combined lime requirement was 41.1 kg/mt ore, for the Oxide composite9.5mm column feed. Higher initial lime additions should be evaluated for these ore types todetermine whether or not pH control will be a problem during commercial heap leaching.Overall, reagent consumption data indicate potential concerns during commercial heapleaching of the Pancho ore, with respect to high cyanide consumptions related to copperdissolution, and high lime consumptions related possibly to interaction with sulphatesnaturally occurring in the ore. Follow-up testing was recommended to better establish baserequirements for pH control during heap leaching of the higher lime consuming Pancho ores.70
Kinross Gold CorporationMaricunga Mine Technical ReportTable 16-7: Pancho and Verde Gold Recovery EstimatesGold Recovery (%)DepositZone2003ColumnTest DataSNCStudy2004$350/ozPit Design2005$400/ozPit Design2006$475/oz PitDesign2006-2007FinalColumnTestsOxide 77 73 67 73 73Verde Mixed 74 70 67 70 70Sulphide 54 53 48 53 53Oxide 89 80 80 85 85 86Pancho Mixed 80 75 75 75 75 77Sulphide 72 70 70 70 70 70Pancho Column Test Work ResultsPrior to conducting the column leach tests, bottle roll cyanide leach tests were conducted onthe samples to confirm metallurgical response and estimate reagent consumptions. Thedata is summarized in Table 16-8. Gold recoveries and reagent consumption rates weresimilar to those established in the 2003 testwork. It is clear that cyanide consumptionincreases with copper content and lime consumption increases with oxidation state. Goldrecovery also increases with oxidation state. It is also clear that gold recovery increaseswith a finer grind confirming that recovery is sensitive to crush size.The column leach test data is summarized in Table 16-9 and charts of gold and copperextraction versus time are appended. The data compiled to date indicates that gold recoveryfrom the Pancho samples tested in 2006-2007 is in the region of 69% for the sulphide oreand 86% for the oxide ore. This test work (Table 16-9) plus the work completed in 2003confirms that the gold recovery values used in the 2007 reserve estimate are reasonable(68% for sulphide, 75% for mixed and 85% for oxide).71
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Technical Report for the Maricunga Gold Mine - Kinross Gold

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