2014-12-29_REPORT - M1977215 - Laserfiche WebLink

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Mr. Randy McClure/Rio Grande Silver, Inc. 5 MLI Job No. 3819 -November 26, 2014 MODIFIED HC KINETIC ARD TEST PROCEDURES AND RESULTS A modified HC kinetic ARD potential testing was conducted on a 1.5 kg split of the BDP-F1391-051113 sample and a 2.0 kg split of the BDP-TBWTC-HC sample at the-1/4" feed size to assess potential of the solids to generate or neutralize acid in an aggressive and accelerated weathering and oxidizing environment. The ASTM standard procedure (D5744-13, Option A) was employed the duration of the 24 week kinetic test(BDP-F1391-051113 sample) and 15 week(ongoing)kinetic test(BDP-TBWTC-HC). The HC test were conducted in seven day cycles. After initial saturation(week 0), dry, filtered compressed air was passed upwards through the solids charge the first three days of the cycle. Humidified air, generated by sparging filtered compressed air into deionized water(DI H2O, pH 5.5) contained in a temperature controlled(30° C)vessel, was passed upwards through the charge for the next three days of the cycle. On the seventh day, the charge was saturated (flooded)with DI H2O and allowed to soak for one hour(0.75:1 ore:water ratio for week 0, 0.5:1 ore:water ratio for all other weeks). After soaking, effluent was allowed to percolate through and drain freely from the solids charge. Effluent was collected in a sealed container and volume was measured by weighing. Unfiltered,unpreserved effluent samples were analyzed immediately for redox potential (Ag/AgC1 reference), pH, EC, SO4, acidity and alkalinity. Separate effluent samples (50 mL) were filtered through a 0.45µm filter to produce extract. Those extracts were analyzed immediately for Fe, Fe" and Fe' (by difference). Remaining weekly effluents were filtered(0.45µm), appropriately preserved and shipped to Western Environmental Testing Laboratory(WET Lab) for the NDEP profile II suite of constituent analyses excluding WAD cyanide and including uranium, ammonia specific conductance and hardness. Extracts for weeks 0, 1, 2, 4, 8, 12, and every fourth week thereafter(not composites)were submitted for analyses. Weekly humidity cell test data for the BDP-F1391-051113 and BDP-TBWTC-HC samples are provided in Tables 6 and 7,respectively. Figures 1 (a and b) and 2 (a and b), which follow Tables 6 and 7 respectively, depict graphically, on a weekly(a figure) and cumulative(b figure) mass basis, analytical data for pH, SO4, acidity and alkalinity. Constituent analysis results for selected weekly extracts are provided in Tables 8 and 9. WET Lab report sheets for profile analyses on extracts are provided in the Appendix to this report. McCLELLAND LABORATORIES, INC.