2019-12-13_REVISION - M1980244 (60)

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ResponseSpill NEWMONT NORTH AWPICA Sustainability & External Relations 4.6 Process Solution Enhancement System(PSES) The PSES Plant is sized to treat the entire volume of process solution at CC&V in a two-stage process.The basic treatment steps consist of: • Combining the incoming pregnant solutions in a large tank/clarifier allowing solids precipitation to occur ahead of the existing gold recovery plant. • Recovering the nascent precipitates along with any carbon fines present in recovery plant effluent using a coagulation/sedimentation process. Clarified effluent from the treatment plant is returned to the Arequa Gulch Valley Leach Facility(VLF-1)through existing pumping/irrigation networks;solids are filter-pressed and bagged for transport and sale to a refiner to recover the contained gold associated with the fine carbon. Capture and sale of product solids prevents carbon from returning to the VLF-1 where it can rob gold from pregnant leach solutions. The system consists of three separate processes: (1)a Pregnant Solution (PS)Stabilization Process to equilibrate the chemistry of the pregnant solutions prior to the ADR-1 Plant; (2)a process solution enhancement system to remove solids from the barren solution before pumping it back to the VLF-1; and (3)a process to dewater the solids removed from the process solution. These processes are discussed in more detail below. Pregnant Solution Stabilization:The PSES process provides the reaction conditions needed to help stabilize the PS prior to the ADR-1.The PS from VLF-1 Phases 1, 2 and 5 flow to the PS Stabilization Tank.The PS from VLF-1 Phase 4 flows to the Enrichment Tank, but could be directed to the stabilization tank if desired.The PS Stabilization Tank provides time for the precipitation reactions to come to completion and settles some of the precipitated solids. These solids are re-circulated to enhance the precipitation process.The system has the ability to periodically feed soda ash to aid the precipitation.The PS pump station transfers the PS to the ADR-1. Barren Solution Enhancement:The system directs the Barren Solution (BS)from ADR-1 Plant Trains A, B, C, D and E to a CoMag process for suspended solids removal. CoMag uses chemical coagulation,flocculation and ballasted sedimentation to remove activated carbon fines, precipitates and other solids.The resulting enhanced barren(EB) solution increases the operating life of the drip emitters on the VLF-1.The EB solution pump station transfers the EB solution to the barren tank. Product Solids Recovery:An important benefit of the enhancement process is recovery of fine activated carbon solids from the BS.Additional gold recovery is expected from these solids as well. 4.6.1 Materials Storage/Secondary Containment Petroleum-based oils or fuels stored at the PSES Facility is limited to two electrical transformers, located outside on the northeast side of the building.The type and quantities of oil in these transformers is listed in Table 7. Occasionally small vehicles such as mine supervisor trucks and delivery trucks will be in the general vicinity of the PSES Plant.Such vehicles conceivably could have spills or tank ruptures nearby. Any spills will be contained inside of the PSES building itself, or within the VLF-1 lined system. Delivery trucks are staged on a concrete pad south of the plant.This unloading and storage area is protected by bollards to prevent accidental collisions between trucks and storage tanks. Any spills or releases of materials from the tanks/containers located outside of the PSE Plant would be contained by the liner and would report to the VLF-1. Spills or releases from the tanks inside the plant would be captured within the building itself. --- -------- _ ___---- _____ -----_.- __-- ----- ------__. ---- ------ __..--- Department THIS DOCUMENT IS UNCONTROLLED IN HARDCOPY FORMAT Doc Id:NA CCV-SER-PLAN- _..._... 1930_ —