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• <br />III IIIIIIIIIIIIIIII ~ <br />'~ STATE OF COLORADO <br />MINED LAND RECLAMATION DIVISION <br />Department of Natural Resources <br />1313 Sherman St., Roam 215 <br />Denver, CO 80203 <br />303 866-3567 <br />Fn%:303 832-8106 <br />DATE: December 22, 1989 <br />T0: Steve Renner <br />FROM: John T. Doerfer <br />RE: Adequacy Review, Amendment No. 1, San Luis Protect <br />Battle Mountain Gold, File No. M-88-112 <br />of ~a~ <br />„~%`~8 <br />~ R <br />~ re 76 ~ <br />Roy Ramer, <br />Gorermr <br />Fretl R. Banra, <br />Division Director <br />As you requested, I have reviewed selected portions of the above-referenced <br />amendment application. My review concerned primarily the hydrologic aspects <br />of the plan. My comments following review are provided below: <br />D. 5 Mill Facilities <br />1. On page D-14, reference to a "dilute cyanide solution" is made in <br />discussing the carbon-in-leach method of ore processing. What is the <br />expected concentration of cyanide in this process solution? <br />2. On page D-16, reference is made to use of sulfuric acid in heating the <br />tailings slurry prior to disposal. An equilibrium diagram i:a provided to <br />indicate that 70% of the cyanide will be volatilized at pH = 9. What is <br />the expected concentration of free cyanide in the treated slurry solution? <br />3. The emergency response plan identifies 6,500 gallons of sulfuric acid as <br />being located on site. At expected production levels, what is the daily <br />requirement or consumption of sulfuric acid? Will sulfuric acid be used <br />as a detoxifying reagent in an emergency spill situation? <br />4. Hydrogen peroxide and alkaline chlorination are referenced for use in <br />the emergency response plan for cyanide detoxification. What reagent <br />will be used for alkaline chlorination? With reference to Table 4.1 in <br />the emergency response plan (Exhibit M), what volumes of reagents will <br />be available for detoxification purposes? What correspondin<q volumes of <br />spills will be detoxified by the amounts of reagents stored on site? <br />5. The results of the depositional modeling tests as to expected cyanide <br />concentrations in the tailings have not yet been submitted. As mentioned <br />on page D-29, this information should be submitted for incorporation in <br />the document review process. <br />