2012-02-28_REVISION - M1980244 (69)

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February 25, 2000 993 -2075 monitor the applied load and a dial gauge measured deformation. The load from the hydraulic jack is adjusted to maintain the desired loading stress throughout the test. 2.2 Test Configuration ROM Cresson Ore For the ROM Cresson Ore sample test,.the ore material was first screened to remove material larger than 2 inches. The screening was done to keep the ratio of the test vessel diameter to the maximum particle size to around six, thereby minimizing any scaling effects. In addition, a study of ore permeability conducted by Lupo (2000') has shown that ore permeability is generally governed by material smaller than 1. to 1 t/ inches. Figure 2 shows the ROM Cresson ore sample prior to testing. The Cresson ore material was placed into the test cell, the initial sample height was recorded and the loading plate was secured. The sample was loaded in five increments to approximately 27, 54, 108, 216, and 432 psi. The load increments correspond to ore depths of 35, 70, 140, 280, and 565 feet, respectively, assuming a bulk ore density of 110 pounds per cubic foot (pcf). Vertical displacement values were recorded at each load increment. The sample was loaded to the next increment only after consolidation had ceased. The sample was saturated with water and allowed to drain prior to the first load being applied. The percolation rate of the material was measured by applying tap water with an electromagnetic pump to simulate various solution application rates. The initial application rate was 0.0045 gallons per minute per square foot (gpm/sf). At each load increment, the application rate was increased to a maximum rate of 0.045 gpm/sf or until ponding was observed on sample. The application rate of 0.045 gpm/sf is ten times greater than the initial application rate and is the maximum flow rating for the testing frame. The sample was allowed to equilibrate (i.e. inflow equals outflow) before increasing the application rate. -During the entire testing period, the surface of the sample was observed for ponding, which would indicate failure of the sample to percolate water at the given application rate. Crushed Minus 7/8 Cresson Ore The crushed minus 7 /8_inch Cresson Ore sample was not screened prior to testing. Figure 3 presents condition of the crushed ore prior to testing. The crushed ore was placed into the test cell, the initial sample height was recorded and the loading plate was secured. The sample was loaded in five increments to approximately 27, 54, 108, 216, and 432 psi. The load increments correspond to ore depths of 35, 70, 140, 280, and 565 feet, respectively, assuming a bulk ore density of 110 pounds per cubic foot (pcf). Vertical displacement values were recorded at each load increment. The sample was loaded to the next increment only after Lupo, John, 2000. Hydraulic Considerations for Leaching Operations, to be presented at the Society of Mining Engineering (AIME) conference, February 28 - March 1, Salt Lake City, Utah.