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~ 1 ~xl~ibit 2 <br />.~ ~ ~ ~ <br />o~TiLE MOUNTAIN RESOURCES, SAN LUIS PROJECT <br />CMLRD ADEQUACY LETTER RESPONSES <br />Page 1 of 28 <br />EXHIBIT D, MINING PLAN <br />1. On page D-14, reference to a "dilute cyanide solutionl" is made in <br />discussing the carbon-in-]each method of ore processing! What is the <br />expected concentration of cyanide in this process solution? <br />RESPONSE: The expected concentration of cyanide in the carbon-in-leach process <br />solution is 0.5 to 0.75 lbs per ton of ore. The s lutions are <br />expected to have total cyanide levels of approximately 175 ppm and <br />free cyanide levels of approximately 60 ppm. As descr bed on page <br />D-16, these solutions are contained in sealed anks only. <br />Additionally, the mill design includes internal cu bing and a <br />solution collection system to further ensure containment within the <br />mill in the unlikely event of a tank leak (see response to question <br />5). <br />2. On page D-16, reference is made to use of sulfuric acid;in treating <br />the tailings slurry prior to disposal. An equilibriu ~ diagram is <br />provided to indicate that 70% of the cyanide will be vo atilized at <br />pH 9. What Is the expected concentration of free cya ide in the <br />treated slurry solution? <br />RESPONSE: Laboratory test methods currently available do not a low for an <br />accurate and consistent determination of free cyanide. ree cyanide <br />is unstable at the pH of the slurry and difficult to mea ure and the <br />test method is subject to interference from other el em nts. Total <br />and weak acid dissociable cyanide tests provide a mo a reliable <br />t indication of cyanide present in a solution. BMR performe laboratory' <br />i testing to evaluate total, weak acid dissociable and f ee cyanide" <br />present in the slurry solution.'The data shows total c,ya ide values": <br />of 4.4 ppm and weak acid dissociable cyanide values of 3.8 ppm. Thee <br />data also indicated free cyanide values of 52.0 ppm, wel~ in excess" <br />of the total and weak acid dissociable values and, therefore," <br />1 physically impossible. In this case, we believe that thi cyanate is <br />causing interference in the testing. The more reliable tot 1 and weak' <br />acid dissociable c snide tests indicate that actual f ee nid <br />evels in the tailin s slurr are below 4.4 m. The labo story test <br />f data is included as Attachment 1 and will be added to Ap endix F of <br />l the permit amendment application. Humidity cell testing s ongoing, <br />however, preliminary test results as well as test resin s from the <br />approved permit indicate that the San Luis ore is not acidic. <br />