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Cross Gold Mine <br />December 2024 U-6 <br /> <br /> <br />flotation cells and is then pumped to a concentrate thickener or filter presses [12] to begin the concentrate <br />dewatering operation. <br /> <br />Dewatered concentrate is discharged and collected in bags and stored for shipment to a smelter or <br />refinery [14]. The water recovered from the flotation circuit is conditioned for reuse in the flotation circuit <br />[13]. Fresh water is added to the flotation circuit as needed [22]. <br /> <br />The de-activated minerals (tailings) from the flotation circuit are pumped [15] to the paste storage area <br />for further drying/decanting. Water yielded from decanted tailings is returned to the flotation water tank <br />in the mill if possible. Dry tailings will be mixed with lime and/or other stabilizing agents to achieve a <br />neutral pH and prevent any metals from mobilizing in the paste mix area [16]. The mixed paste will then <br />be pumped, hauled, or conveyed back underground into mined out workings for final placement [17]. The <br />paste backfill process will leave a low-moisture, non-acid generating material in old mine workings and <br />voids. This will accomplish multiple objectives for the Cross Gold Mine: <br />• Stabilize mine tailings in an inert form to prevent any long-term metal leaching or acid mine <br />drainage. <br />• Backfill underground voids to prevent future subsidence or ground movement. <br />• Plug terminus points of veins and other geologic structures that would otherwise be flow paths <br />for groundwater to interact with otherwise isolated geochemistry. <br />The permittee is currently working with paste backfill technology companies to develop a pilot program <br />to test paste backfilling as a final tailings storage option. Development of the mill facility will only occur if <br />paste backfilling or another appropriate permanent tailings storage method is approved by CDRMS. As <br />such, the mill layout and process delineated here is conceptual and only intended to be a general guide <br />for CDRMS and the permittee. A technical revision detailing all mill design specifics, construction <br />schedule, construction QA/QC, and an as-built will be submitted to CDRMS prior to any mill development <br />activity at the Cross Gold Mine. <br />Reagent storage will take place in the mill. An indoor storage area [19] and an outdoor storage area [20]. <br />The outdoor storage area will primarily be used to handle deliveries and only hold reagent containers for <br />a short time before they are stored long term within the mill. All reagent storage areas will be lined and <br />contained in a manner like that shown on Map C-4. <br /> Off-site Tailings Recovery Plan <br />In the event that tailings material leaves the mill, recovery action will be undertaken. Recovery will <br />consist of the following steps: <br />1. Identify the extent and location of the off-site tailings with GNSS and photographs. <br />2. Report the off-site location, extent, and quality to CDRMS within 24-hours of identification. <br />3. If tailings deposition is fresh and does not have vegetation established within it, excavate the <br />tailings down to 6-inches into the natural ground or to bedrock, whichever is shallower.