2012-10-05_REVISION - M1977342 (12)

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TR -18 to Permit M- 1977 -342 Environmental Protection Plan Sodium hydroxide is used in the mill circuit to neutralize waters in the lead leach process and to make Nokes reagent for use in the flotation 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, may lead to death. 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 is 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 to potentially intolerably high levels. Direct long -term impacts would be negligible to non - existent since sodium hydroxide does not bio- accumulate. However, at high pH levels, several metals (e.g. aluminum) increase in concentration and can cause indirect long -term impacts. Hydrochloric acid is used in the mill circuit in the lead leaching process. It is an acidic corrosive that can affect the human body through inhalation, ingestion, and dermal contact. It is corrosive to any tissue with which it contacts. Effects can vary from mild irritations to severe burns (internally 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. Hydrochloric acid is acid forming in aquatic and terrestrial environments. It can be neutralized with the application of alkaline materials. Cytec OrePrep F -579 (or equivalent) is utilized in the mill circuit as a flotation frother. It is a non - hazardous mixed polyglycol. Direct contact with this material may cause mild eye and skin irritation. OrePrep F -579 is a stable product that is completely miscible with water. It is not considered an environmental hazard. It does not contain OSHA regulated (hazardous) components. Orform D8 Depressant (or equivalent) is a mineral processing aide that is used in the mill circuit to suppress other metals in the flotation process. This is a corrosive material that causes eye and skin damage. The vapor is combustible and may cause respiratory tract irritation if inhaled. The material can be harmful or fatal if swallowed. Pine Oil is composed of terpene alcohols and hydrocarbons and is used in the mill circuit as a frother reagent. In humans, it may cause skin and eye irritation and may be harmful if ingested or inhaled. However, it is neither characteristically hazardous nor listed as hazardous under federal regulations. Pine oil is stable and non - persistent in the environment. Collector Oil (Vapor Oil - Calumet Hydrocal 60 or equivalent; Diesel #2 may be used as a backup) is a light naphthenic petroleum oil which is used in the mill circuit as a collector /rougher reagent. It is non - hazardous and practically non -toxic through dermal or ingestion pathways. In the environment, this reagent is stable. It should be treated similar to any petroleum product should spills or releases occur. Diesel fuel #2 is a combustible petroleum distillate commonly used as a heating fuel. At the Henderson Mill, it may be used as a collector reagent in the milling process in place of vapor oil. Climax Molybdenum Company Henderson Operations October, 2012 Page 10 of 40