2011-12-15_REVISION - M1977493 (2)

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Technical Revision (TR -18) Climax Molybdenum Company Environmental Protection Plan Permit No. M- 1977 -493 concentrations, lime can cause caustic irritation, inflammation, and bums through inhalation and dermal contact. Excessive amounts of lime in the environment can raise alkalinity to damaging levels. In aquatic systems, excessive lime also can cause potentially damaging precipitation /sedimentation. T - 3.3.3 Sulfuric Acid Sulfuric acid (H2SO4) is used to adjust the pH of treated water to within the permit stipulated range of pH 6.5 - 9.0 prior to discharge to Tenmile Creek. Sulfuric acid is a corrosive that can affect the human body through inhalation, ingestion, and dermal contact. Effects can vary from mild irritations to severe bums (intemally or externally) depending upon the type, degree, and length of exposure. Repeated chronic exposure to dilute solutions may cause dermal irritations, whereas similar exposure to vapors or mists may cause erosion of teeth and inflammation of the eyes and mucus membranes of the nose, throat, and lungs. In the environment, sulfuric acid can be directly toxic through its corrosive nature or by lowering pH levels to the point of toxicity. In addition, even in very dilute forms, which may not be injurious to human health, chronic releases of sulfuric acid can dissolve metals from rocks which, in turn, can damage aquatic and, in some instances, terrestrial ecosystems. Sulfuric acid is readily neutralized by the addition of alkaline substances such as NaOH, CaO, or limestone. T - 3.4 Material Safety Data Sheets for Designated Chemicals Current Material Safety Data Sheets (MSDS) are attached in Appendix T -B. Updated MSDSs are maintained at the site. These data sheets list permissible exposure limits, monitoring and measurement procedures, health hazard information and exposure effects, recommended medical procedures for human exposure, emergency first aid procedures, personal protection, leak and spill procedures, and waste disposal methods. T - 3.5 Disposal, Decommissioning, Detoxification or Stabilization Procedures for the disposal, decommissioning, detoxification or stabilization of designated chemicals during temporary cessation or final closure are discussed in the following sections. T - 3.5.1 Temporary Cessation /Prolonged Lack of Mineral Production Under the scenario of formal temporary cessation or periods of prolonged lack of mineral extraction and production, designated chemicals at Climax would be used or removed from the site. Mixed chemicals such as Nokes Reagent and NaCN in solution would be used in the milling process until depletion of the supplies. The distributor would be contacted to assume possession of unmixed and uncontaminated chemicals, and the material would be transported off-site in the same manner that it was received at the site. Those designated chemicals used in the water treatment system at Climax would remain at the site and would continue to be used. Water treatment and discharge would not cease under these scenarios. If unmixed chemicals were contaminated or the distributors were to decline possession, then detoxification or stabilization and disposal would be managed pursuant to solid and hazardous waste regulations. T - 3.5.2 Final Closure Upon final closure at the conclusion of operations at Climax, designated chemicals will be handled in similar fashion as under the scenario described above. The exception is that lime, sulfuric acid, and flocculant used in the water treatment process will remain at the site until no longer required in the water treatment process. Removal and disposal of water treatment chemicals will occur as discussed for mill process chemicals during periods of temporary cessation or prolonged lack of mineral production. EPP: Version R2 T -13 December 2011