2020-08-03_REVISION - M1980244 (9)

Home Browse Search

Cripple Creek & Victor Gold Mining Company Exhibit U Cresson Project Amendment 13 3 Table U-1: Designated Chemicals Chemical Name Use at the Site Location for Use Location for Storage Typical Quantities Used and/or Stored on Site Secondary Containment Provided Fate of Chemical Sodium Cyanide Delivered to the site as liquid cyanide and either mixed or direct- offloaded to the ADRs and/or HG Mill facilities. Used as a dilute solution for leaching and product recovery. VLFs, ADRs, and HG Mill facilities The sodium cyanide is delivered as a liquid to the ADRs and the HG Mill facilities via tanker truck. The tanker truck parks within containment during mixing and offloading to holding tanks. There are two holding tanks for sodium cyanide at the ADR1, two holding tanks at the ADR2, and one holding tank at the HG Mill facility. Each holding tank is 20,000 gallons in size. At least one 7,500-gallon tanker is staged at each facility on any given day. The offloading of cyanide occurs within secondary containment at the ADRs and HG Mill facilities. The holding tanks also are located within secondary containment on concrete foundations with curbing. The ADR1, ADR2, and HG Mill facilities are underlain by a geomembrane liner system for tertiary containment. Is consumed in the dilute sodium cyanide solution leach circuit – see next row for ultimate fate of sodium cyanide process solutions. Dilute Sodium Cyanide Solution Barren solution is piped from storage locations to the VLFs and pregnant solution is piped from VLFs to PSES and ADRs. Dilute sodium cyanide solution is used in the HG Mill facilities to bring the gold into solution from both the ground product and the carbon. VLFs, ADRs and HG Mill facilities ADRs, cyanidation, and CIP tanks in HG Mill and in PSSAs within the VLFs. At each of the ADRs: - Internal barren tank of 20,000 gallons - Strip pregnant tank of 20,000 gallons - Strip barren tank of 20,000 gallons - Two Strip intermediate tanks of 20,000 gallons each - Two barren enrichment tanks of 80,000 gallons each at VLF1 only 29,100 gpm being applied at VLF1 at a strength of less than 250 mg/L sodium cyanide. 17,000 gpm to be applied at VLF2 at a strength of less than 250 mg/L sodium cyanide. Solutions are continuously re-circulated between the VLFs and ADRs. At the HG Mill facilities: -20,000 gallons mixing tank 211 gpm (77 tons of slurry per hour) being continuously circulated within the HG Mill facilities at a strength of 2,500 mg/L sodium cyanide At the PSES: - Pregnant Solution Stabilization Tank – 850,000 gallons - CoMag Clarifier – 660,000 gallons - Gravity Thickener– 285,000 gallons Dilute sodium cyanide solutions have primary, secondary, and tertiary containment at the VLFs, ADRs, and HG Mill facilities. Piping is within secondary containment or double-walled when outside of containment. See Exhibit D for complete details of the containment. The VLFs will be rinsed as will any tanks and lines that have contained sodium cyanide process solutions. Dilute sodium cyanide solutions are expected to breakdown during rinsing. Upon completion of rinsing, the dilute solutions will be treated with hydrogen peroxide or circulation enhanced to allow evaporation of water. Sodium Hydroxide (Caustic Soda) Used for pH control VLFs and ADRs Stored in liquid form at ADRs 20,000-gallon tanks at each ADR Tanks are within concrete containment and also located on the lined area of the VLFs. Concrete containment is equipped with a float-activated pump that would return fluid to the plant in the Is consumed in pH control for process solutions.