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:0:51 $80~8a 8J28 ASCI tra:~C0ir4'El~ - ~.- <br />f~00_ OOi <br />A S C I <br />Adrian Smi}h <br />Conwlling Intorparared <br />2555 "cdgemonr Boulenord <br />Nonfi Vancouver, e,C. <br />Canada V7R 2M9 <br />T•I•phone: 6049842524 <br />Fax: 604.9848426 <br />MEMORANDUM <br />June 1, 1992 <br />T0: Dr Harry Posey, CMLRD, Donver, CO <br />FROM: Adrian Smith <br />ASCI, Vancouver, B.C. <br />RE: Calculation of maximum theoretical free cvanide levels: San Luis Praiect. CO <br />As requested, herewith the details of the calculations for maximum theorejtical 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 spigot), could not he computed. <br />For reference, I have appended a copy of the data summary table far 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 methotl, is 385 mg/L. The measured <br />WAD CN is 358 mg/1. Calculation of the metallo-cyanide complexes irv the sample li.e. <br />copper, nickel and zinc), which form part of the WAO CN are as follows: <br />• copper (case A, as Cu(CN12): <br />equivalent amount of cyanide required to form the Cu1CN12 complex with the <br />copper is copper 163) multiplied by cyanide (261 twice 1521 which is 0.825 <br />i.e. 52/63 = 0.825. The copper value for sample 1 was 20'5/210 mg/L <br />which requires 208 X 0,825 = 172 mglL cyanide. <br />mm«~r <br />