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SODIUM HYDROXIDE (LIQUID) - NoKES BuaDlnlc • Sodium hydroxide (NaOH) is mixed with phosphorus pentasulfide (P2S5) and water to make Nokes. NaOH is also mixed with sodium cyanide (NaCN) and water to make a cyanide solution used in the grinding portion of the milling process. NaOH is also used in the lead-leach circuit to neutralize the acid solution. A 50 percent solution of NaOH arrives by tanker and is transferred into two storage tanks of 12,300 gallons each in the Nokes building. The Nokes building has been modified to provide containment for 110 percent of the largest tank volume. The NaOH tanks are also equipped with sonic level detectors and local alarms that warn of high tank level. 'fhe floor of the NaOH storage tank room is sloped towards a sump which pumps any spills to the thickener. This sump also contains a high level alarm which would provide warning in the event of a large release such as a tank rupture. Sodium cyanide and sodium hydroxide are mixed and used in the grinding and flotation phases in the mill process (see SODIUM CYANIDE for a more complete description). Sodium hydroxide and phosphorus pentasulfide are mixed and used as Nokes reagent in the flotation process (see PHOSPHORUS PENTASULFIDE). SODIUM HYPOCHLORITE Sodium hypochlorite reacts with acids or moisture to evolve free chlorine at room temperature. It is hazardous in contact with combustibles, organics, or easily oxidizable materials and could cause a fire. Sodium hypochlorite is fed into the influent to the potable water trE:atment system at an anticipated rate of one to two gallons per day from a 5!i gallon drum. This drum will be stored in a concrete block building near the potable water storage tanks, and since only a small amount is utilized, the I~uilding itself would contain any spill from the drum. Extra drums are stored in the Flammable Materials /Hazardous Waste Storage Building. SULFURIC ACID Only small amounts of sulfuric acid are stored and used at the mill. Approximately 5 gallons of sulfuric acid are stored in the battery room of the locomotive shop at the mill and used for batteries on the train locomotives. Used batteries, including the sulfuric acid within the cells, are shipped offsite • by a commercial vendor for recycling and / or proper disposal. Approximately 10 gallons of sulfuric acid are stored in the assay laboratory acid ;storage room. Any used acid generated in the assay laboratory is diluted with water and disposed in the tailings basin. Page 10