Laserfiche WebLink
be covered from the mill portal as shown on Maps C -2, C -3 and C -4 to a steel building of <br />dimensions 20 feet x 30 feet x 20 feet high. It will have a 6" thick steel reinforced concrete <br />foundation. The tailings material size is approximately 200 mesh and due to the water filter <br />recycling, the water content of the tailings will be approximately 13 -16 %. This building will have a <br />large garage door on the north side. From this opening, a backhoe or other machine will load the <br />tailings on a 14 ton truck, which will deliver the tailings to either the Revenue Waste Pile or the <br />Atlas Waste Pile to the west. At either of these piles, dozers will compact the waste in 6" lifts to a <br />94% maximum dry density. Quality control density samples of the compacted waste will be <br />conducted using a field density instrument every 2000 tons of tailings that are placed. As described <br />in the Mine Plan, the piles will have slopes no steeper than 3H1V. A slope stability analysis of the <br />worst case tailings pile has been conducted and is included in Exhibit U. <br />The tailings from the mill have the potential to contain acid and/or toxic forming material since the <br />ores contain gold, silver, lead, zinc and copper, and much of this ore is in the form of sulfides. <br />CH2M Hill of Denver, CO has designed the underground mill for this site. From the start, one of <br />the objectives of the mill design was to ensure that the tailings from the process are inert. Normally, <br />older mill designs crushed the ore and then ground the ore to powder sizes and then used flotation <br />cells to float the valuable sulfide minerals for sale. Any iron sulfides such as pyrite, marcasite and <br />other base metal sulfides were not extracted and the tailings were then deposited near the mill. Over <br />time, the sulfides could potentially oxidize and produce some sulfuric acid, which then results in <br />other metal ions becoming soluble and potentially negatively affecting the effluent from the piles. <br />This mill design will employ additional flotation cells or employ other equipment, as necessary, to <br />ensure that the tailings from the processing operation are inert. Base metal sulfides may be <br />collected and trucked offsite for disposal in an approved facility, if required, to achieve the inert <br />status of the tailings. <br />By employing these items in the mill, the tailings produced from the process will be inert and not <br />susceptible to oxidation over time where metals and/or acid could leach out of the tailings and make <br />their way into the surface water or ground water system. <br />Revenue Mine August 2012 T -12 <br />