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original design but was added later to help with eliminating water from the tailings, in combination with the <br />filter presses. Leaving the thickener, the slurry is now approximately 45-50% solids. The slurry is pumped to the <br />18,000 gallon tailings slurry tank in the filter building, where it is then distributed to both banks of filter presses <br />on the second floor of the building. Here the water is squeezed out of the tailings and the cake tailings are <br />allowed to drop down into two concrete floor bays, where a front end loader will load the fines out for <br />permanent placement in the Revenue and Atlas tailings embankments, where the material is compacted and <br />reclaimed. The tailings from the filer presses will be approximately 17% moisture, which is appropriate for good <br />compaction in either of the two permanent embankments in the permit area. <br />3. Mill Construction, Modifications and Test Operation <br />The mill tunnels were blasted from inert waste rock in 2013 and the mill was primarily constructed in late 2013. <br />In 2014, the mill underwent initial testing and various adjustments were made to increase efficiency and ensure <br />that environmental compliance was met. The significant changes are listed below: <br />a) Various trials of chemicals used in the mill process were made to maximize sulfide recovery and provide <br />for inert tailings. <br />b) New high capacity slurry pumps (Gallagher pumps) were set in the underground sumps to ensure that <br />slurry or water building up on the mill floors could be removed quickly and efficiently. <br />c) Laboratory equipment was installed in the mill and the filter building to provide continuous monitoring <br />of the chemistry of the concentrate and the tailings. <br />d) A 26 feet diameter thickener was installed outside the filter building which provided an initial step of <br />tails dewatering, prior to the tails entering the filter presses. The thickener was completed in mid -2015. <br />Commissioning of the mill included the testing of concentrate, tailings, and also the ground water wells which <br />were installed at the toe of the Revenue tailings and waste rock embankment and the Atlas embankment, which <br />has not yet received tailings or waste rock. Initial tailings produced from the mill testing process were mixed <br />with waste rock and placed in the void from the old Revenue Pond. This pond will ultimately be completely filled <br />with tailings and waste rock. <br />Revenue Mill Certification Page 5 of 20 <br />