2012-02-28_REVISION - M1980244 (77)

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a liaSmiurH 1 Design Summary Squaw Gulch High Grade Mill Facilities 1/24/2012 Page 2of6 The rod mill trommel screen undersize slurry will flow into the Primary Cyclone Feed Sump at a rate of approximately 250 tons per hour where it will be combined with the ball mill discharge. The combined rod mill product and ball mill products will be pumped to the Primary Cyclone Cluster at a rate of approximately 950 tons per hour. The Primary Cyclone Cluster will separate the slurry fine particles which are approximately 150 microns in diameter from course particles. The cyclone overflow (fine particles) from the cyclone cluster will flow by gravity to the flotation feed conditioner tank. Cyclone underflow (course particles) will flow by gravity back to the ball mill for further size reduction. In the event that there is free gold present in the slurry, a gravity concentrator system will be used to capture this gold. When the gravity system is on -line, 50% of the Primary Cyclone Cluster underflow will be sent to the Gravity Concentrator System. Cyclone underflow split to the gravity concentrator will gravitate to the Cyclone Underflow Sump. Two variable speed pumps, one as stand -by, are set to feed cyclone underflow from the Cyclone Underflow Sump to the Gravity Concentrator Feed Screen. The overflow from the Gravity Concentrator Feed Screen will gravitate to the ball mill feed chute for further size reduction. The underflow from the gravity concentrator screen will gravitate to the Gravity Concentrator. The Gravity Concentrator is a centrifugal concentrator that separates heavy (gold) particles from the lighter particles in the slurry. The captured heavy particle concentrate from the gravity concentrator will collect in a concentrate decant tank and will be transported via a concentrate transport container to the existing Arequa Gulch Adsorption, Desorption and Recovery (AGADR) facilities for further processing. The remaining product from the gravity concentrators will be recycled back into the ball mill. 2.3. Flotation Systems The flotation system concentrates the volume of the gold bearing ore further. The flotation system consists of agitated cells (tanks approximately 13,000 gallons in size each) where air and reagents (lime, frother, promoter, and potassium amyl - xanthate) are added. The reagents and air produce bubbles on which the gold bearing ore adheres to and are then captured for further processing. This reduces the volume of material that must be handled in the gold recovery systems downstream of the flotation system. The ore that does not float is rejected from the cells and is processed in the processed ore system. The Primary Cyclone Cluster overflow (fine particles) from the grinding circuit will flow by gravity to the flotation feed conditioning tank (approximately 16,000 gallons in size). The reagents are added in the conditioning tank which encourage bubble formation and attraction