Technical Report for the Fort Knox Mine - Kinross Gold

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Fort Knox Mine Technical Report12.1.2 Reverse Circulation - Wet SamplesCuttings are fed into a cyclone that deposits a stream of sample and drilling fluid into asplitter with a variable speed hydraulic motor that rotates a set of vanes controlling thevolume of split sample. Prior to 2006, this split sample was fed into four 5-gallon bucketsset in cascading series to collect and settle out the cuttings. A flocculent was added tothe first bucket to aid in the settling of the sample. The samples were then permitted tosettle. Beginning in 2006, the split sample was fed into one, perforated and lined, 5-gallon bucket placed in a washtub to collect all of the overflow. A flocculent was addedto the bucket to aid in the settling of the sample. All of the overflow material was washedback into the bucket to avoid any loss of material. The single bucket procedure wasutilized for the 2007 drill sample collection as well. Wet RC samples are reviewedcarefully for the possibility of down-hole contamination (see Section 14.1).12.2 Core SamplesPQ (85.0 millimeter, or 3.345 inch) and PQ3 (83.1 millimeter, or 3.270 inch) diametercore holes were drilled at the Fort Knox deposit. Detailed log sheets prepared for corerecord lithology, mineral type, alteration, oxidation, color, vein percent, structure and veinorientations. Geotechnical data including RQD, core recovery, and fracture logs are alsorecorded. Hardness values ranging from R0 to R6 were documented beginning in 2005and is ongoing. The core is then photographed, logged, and sampled at 1.52-meter (5foot) intervals. MRDI (1991) indicated that diamond drill core has the potential to slightlyunderstate the grade at Fort Knox.12.3 Sample Composite SummarySample composites reflect the weighted average grade per hole over the bench height.Composite length can vary. Vertical holes show composite lengths of 9.1 m (30 feet =bench thickness) while inclined holes display longer composites, depending on their dip.Table 12-1 depicts the most important statistical parameters of the composite samplepopulation, segregated by domains.38
Fort Knox Mine Technical ReportThere are 15,721 composite samples of which 2,181 are in the schist and the remaining13,540 in the combined domains of the intrusive (1677 in Domain 10, 5750 in Domain 20and 6041 in Domain 30).The reliability of the data is expressed by the coefficient of variance (CV = Standarddeviation divided by the mean). The closer CV is to 1 the more dependable is thepopulation of samples. CV is furthest away from 1 in the schist, indicating the highestvariability of samples in this unit. Within the intrusive, Domain 20 has the lowest value,but the difference to the other intrusive domains (Domain 10 and 30) appears not to beof significance.Composites are used to assign grade values to the block model. Because of statisticaland field observations the grade of the schist is modeled as missing and is therefore notincluded in reserve calculations.Table 12-1: Composite Summary TableStatistic Schist Domain 10 Domain 10 Domain 10 All SamplesNo. Samples 2,181 1,677 5,750 6,041 15,721No. Missing Samples 119 28 101 66 314Min. (opt) 0.000 0.000 0.000 0.000 0.000Max. (opt) 0.205 0.215 0.248 0.239 0.248Mean. (opt) 0.003 0.015 0.020 0.016 0.016Std. Deviation 0.010 0.020 0.025 0.022 0.022C.V. 3.278 1.288 1.249 1.313 1.41539
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Technical Report for the Fort Knox Mine - Kinross Gold

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