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May Day Idaho Mine Complex 112 (d) Permit Application <br />(b) Expected Concentrations, Process Solution Volumes and Fate <br />The present milling plan describes the predicted amount of chemicals to be used per ton <br />of ore (Section 6.4.4a). Approximately 0.25 ton of water will be used for every ton of ore <br />milled. Based on the assumption that 0.25 ton of water weighs 227 kg, the following <br />concentrations are expected within the milling solution. <br /> lbs/ton rock kg/ton rock g/L solution <br />Sodium carbonate 3.0 1.36 6 <br />Sodium Silicate 0.25 0.11 1 <br />Surfactant 1.0 0.45 2 <br />Potassium amyl xanthate 15 6.82 30 <br />Sodium alkyl dithio hos hate 0.05 0.02 0.1 <br />Copper Sulfate 0.05 0.02 0.1 <br />Frother 0.10 0.05 0.2 <br />Approximately 3,000 gallons (395 ft) of solution will be contained within the mill tanks <br />at any one time. <br />The tailings are proposed to be disposed within dry, underground workings of the mine <br />(Section 6.4.20.19). The milling process calls for 75% recycling of water, which will be <br />. achieved through the use of cyclones prior to tailings disposal. The combination of <br />minimal water within the tailings and the lack of water within the disposal facility (see <br />Section 6.4.20(19)) is predicted to prevent any exposure pathway via leaching to <br />groundwater. This will be evaluated during the milling optimization phase during start- <br />up. <br />(c) Material Safety Data Sheets (MSDS) <br />MSDS sheets are presented in Attachment T-1. <br />6.4.20(6) Designated Chemicals and Materials Handling <br />(a) Procedures for Disposal, Decommissioning, Detoxification, Stabilization <br />All chemicals will be used entirely in the milling process and will be stabilized within the <br />mine tailings. As described in section 6.4.20(5), the tailings will be disposed within dry <br />underground workings. This will be confirmed during the mill optimization phase and a <br />disposal procedure will be submitted to the Division for review. If other disposal options <br />are identified during the milling optimization phase, these will be presented to the <br />Division in a Technical Review document. <br />Further details regarding tailings disposal is described in Section 6.4.20(19). <br />• <br />May Day Idaho Mine Complex I I2(d) Permit Application <br />September 21, 2010 <br />4