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' ~ III IIIIIIIIIIIIIIII • ~ • ~-/ / ~~ <br />A S C I <br />~-~~ tl2 -~ ~~~Ev <br />Adrian Smith UN <br />Consulting Inwrporoted rll <br />2555 Edgemont Boulevard A,, lggt <br />North Vancouver, B.C. R MlRed <br />Canoda V7R 2M9 ~(.`~~ma+/~~ ^nd <br />Telephone: 604-984-2524 <br />I <br />Fax: 604-984-8426 MEMORANDUM ^ ,7 <br />June 1, 1992 <br />TO: Dr Harry Posey, CMLRD, Denver, CO <br />FROM: Adrian Smith <br />ASCI, Vancouver, B.C. <br />RE: Calculation of maximum theoretical free cvanide levels: San 4uis Protect. CO <br />As requested, herewith the details of the calculations for maximum theoretical free cyanide <br />levels in three of the four tailings samples taken from the San Luis Project tailings system on <br />May 11, 1992. The absence of reliable WAD CN data meant that the free cyanide level of <br />the fourth sample, (taken at the spigotl, could not be computed. <br />For reference, I have appended a copy of the data summary table for the May 11, 1992, <br />tailings samples and a description of the general approach to calculating mass balances for <br />cyanide, from Smith and Mudder, 119911. <br />SAMPLE 1: Pre-Detoxification <br />The total cyanide in this sample, using the manual TCN method, is 385 mglL. The measured <br />WAD CN is 358 mg/I. Calculation of the metallo-cyanide complexes in the sample (i.e. <br />copper, nickel and zincl, which form part of the WAD CN are as follows: <br />copper (case A, as Cu1CN121: <br />equivalent amount of cyanide required to form the Cu1CNl2 complex with the <br />copper is copper (631 multiplied by cyanide (261 twice 4521 which is 0.825 <br />i.e. 52/63 = 0.825. The copper value for sample 1 was 205/210 mg/L <br />which requires 208 X 0.825 = 172 mg/L cyanide. <br />Ibmpcncal <br />