Laserfiche WebLink
<br />• As an observation, if the material were crushed, the percentage of fines would increase as <br />a result of breaking up the oversize material. The avoidance of crushing of this run-of-mine <br />material reduces the amount of fines that would otherwise be sent to the Valley Leach Facility. <br />• The run-of-mine ore is placed on the Valley Leach Facility concurrently with crushed ore. <br />This is done because the run-of-mine does not have lime added prior to placement in the Valley <br />Leach Facility. To adjust for this temporary lime deficit during placement of run-of-mine <br />material, lime is added to the crushed ore at a higher rate than normal. The mixing of the run- <br />of-mine with this higher-lime-content material effectively mixes lime with the run-of-mine <br />material. The mixing is accomplished by staggering the loads such that the "shingled" effect <br />you and your staff observed is created. At present, a dozer pushes the combined material down <br />the advancing face of the ore lift, which is about 35 feet high. <br />• Examination of the areas of the Mine where run-of-mine material is encountered has shown <br />no evidence of perched water tables or excessive dampness in the insitu material. Therefore <br />there is no evidence that, under insitu conditions, the run-of-mine material has any different <br />water permeability characteristics than the material that is to be crushed. Visual analysis of the <br />minus 6-inch material provides the basis to characterize the material as a gravelly-sandy loam. <br />• As noted above, Amendment Number 6 did not specify that all ore would be crushed. <br />Neither did CC&V specifically describe run-of-mine because CC&V did not consider this <br />necessary. The OMLR will recall that in Amendment Number 5, run-of-mine was planned for <br />a substantial area. The OMLR will also recall that at no time did this proposed placement of <br />run-of--mine material generate concern. <br />• If CC&V had assessed any permeability or recovery issues with the run-of-mine, it would <br />consider and propose agglomeration. Agglomeration is not believed to be necessary or useful <br />here because there are no indications of excessive fines leading to leaching delays. <br />• At this time, less than 6 percent of the ore on the Cresson Valley Leach Facility is run-of- <br />mine material. About 1 percent of this amount is hauled directly to the Valley Leach Facility <br />because of wood or metal (or both) content that would foul the crusher. This 1 percent would <br />pass easily through the crusher if it were not for the anthropogenic debris it contains. <br />• CC&V has conducted tests of both Run-of-Mine and crushed ore. These were saturation <br />tests that give the time to "break-through" of applied solution. Run-of-Mine material consisting <br />of the minus 6" portion, was loaded into vertical 10" diameter columns. Similar columns were <br />loaded with crushed material (the full size fraction). Solution was applied to the top of the <br />columns at measured rates. The time until water appeared at the base of the column was <br />measured for comparison. At a flow rate of 0.005 g/m/ftz, 4-foot columns demonstrated break- <br />through times of 753 minutes for the crushed material and 79 minutes for the ROM. At the <br />same flow rate of 0.005 g/m/ftZ, 8-foot columns of crushed and ROM produced break through <br />times of 1546 and 149 minutes, respectively. Thus there is no evidence of ROM material <br />decreasing the rate at which water passes through the ore. In fact, the limited data suggest that <br />2 <br />