2021-08-17_REVISION - M1977342 (4)

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TR-34 to Permit M-1977-342 Environmental Protection Plan the mill process water circuit as a whole as well as allow for the precipitation of some metals within the TSF. Contact can cause irritation to eyes, skin, respiratory system, and gastrointestinal tract. Quicklime reacts violently with water, releasing heat which may ignite combustible materials in certain instances. Contact with eyes can cause severe irritation or burning, including permanent damage. In the presence of acidic conditions such as acid rock drainage or acid mine drainage, quicklime reacts as an acid neutralizer and buffer. It can be used to raise the pH of acidic waters. Should quicklime be delivered directly into a non-process water or a non-acidic water environment, it would cause short-term impacts to aquatic communities by raising the system pH. Direct long- term impacts would be negligible to non-existent since calcium hydroxide would neutralize in the natural system and does not bio-accumulate. Sodium hydroxide is used in the mill circuit to neutralize waters in the lead leach process. It is a strong corrosive alkali that can affect the human body through inhalation, ingestion, and dermal contact. Effects can vary from mild irritations to destructive burns (internally or externally) depending upon the type, degree, and length of exposure. Severe exposures, particularly those resulting from ingestion, can be fatal. In the presence of acidic conditions such as acid rock drainage or acid mine drainage, sodium hydroxide reacts as an acid neutralizer and buffer. It can be used to raise the pH of acidic waters and soils. Should sodium hydroxide be delivered directly into a non-process water or a non-acidic water environment, it would cause short-term impacts to aquatic communities by raising the system pH. Direct long-term impacts would be negligible to non-existent since sodium hydroxide would neutralize in the natural system and does not bio-accumulate. Sodium Lauryl Sulfate (Naxolate or equivalent) is a solid, flake-form, non-hazardous particulate surfactant used in the Mill circuit as a frother/soap. It is a frothing agent that is mixed with hot water to form Syntex in the mill process. It is non-reactive, slightly flammable, and a slight human health hazard. Eye protection and gloves should be worn when in contact with the product. Decomposition products from burning are carbon monoxide and carbon dioxide. In the environment, Naxolate is stable and non-hazardous. Syntex (or equivalent) is a non-hazardous particulate surfactant used in the mill circuit as a frother/soap. Syntex is Sodium Lauryl Sulfate mixed with hot water. In humans, it may lead to possible irritation of the gastrointestinal tract if ingested in quantity. It is stable and non- hazardous in the environment. Tergitol NP-9/91\19 or N95 Surfactant (or equivalent) is a nonylphenol polyethylene glycol ether used as a nonionic surfactant in the lead leach circuit in the Mill. This reagent is stable, and essentially is non-hazardous to humans, but it can cause skin and eye irritation with prolonged contact. In the environment, NP-9/91\19 or N95 may be toxic to aquatic organisms and has a tendency to bioaccumulate. Hydrated Lime (water treatment) will be used for metals precipitation in the Mill WTP. Lime is used to raise the pH of the water being treated to alkaline conditions, and metals are subsequently oxidized and precipitated. Contact can cause irritation to eyes, skin, respiratory system, and gastrointestinal tract. Hydrated lime does not react as violently with water as Climax Molybdenum Company August,2021 Henderson Operations Page 12 of 45