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s __ _ <br />_O:S2 $`80~ • 3.1:8 dSCI ViNCOi"t'ER • I~j00J:OOi <br />A 5 t I <br />'nickel (as NilCN14-: <br />equivalent amount of cyanide to form the Ni1CNl4 complex with 0.5 mg/L <br />nickel, is nickel (571 multiplied by cyanide 126) four times (1081 i.e. 108157 <br />= 1.895 which is about 1 mg/L. <br />• zinc l as Zn(CNI4i: <br />equivalent amount of cyanide to form the 2nICNl4 complex with 1.6 mg/L <br />zinc, is zinc (651 times cyanide 1261 four times (1081 i.e. 108!65 = 1.66 <br />which is about 3 mg/L. <br />based an the above metallo-complex speciation, the total amount of WAD CN needed to <br />form these complexes would be 176 mplL. Based on the analysed WAD CN of 358 mg/L, <br />this implies a maximum theoretical cyanide level in the pre-detoxified tailings of 182 mg/L. <br />In practice, we have assumed that the copper cyanide is as the CuiCN12 complex. This is <br />unlikely to be the case, as the most common form of copper cyanide complFax in tailings - <br />solutions is as Cu1CN13, see Simovic and other workers, (1989 and others/. <br />If the capper values are recalculated for the Cu1CNl3 complex, we would have the following <br />~'v <br />1. calculation: 208 X 78163 = 257 mg/L. Adding the metallo-cyanide complexes of zinc and <br />~ ~ nickel, this would give a total of 261 mg/L, resulting in a residual maximum theoretical free <br />cyanide value of 358 - 257 = 101 mglL FCN. <br />SAMPLE 3: Lower Pond <br />This method is a repeat of the above calculation. Total Cyanide bV the manual method is <br />189 mg1l.. The WAD CN determination gave 166 mg/L. `/"' <br />Copper cyanide, as CulCN12, taking the lowest copper number, is 16Z X 52/63 = 133 <br />mg/l; nickel is the same as sample 1 at 1 mglL; zinc is 0.45 X 108/65 /else than 1 mplL; <br />which gives a total of 134 mp/L calculated metallo-cyanide WAD complexes. Therefore, the <br />maximum residual free cyanide is the WAD CN determination of 166 less the total of the <br />WAD CN metallo-cyanide complexes, which is 166 - 134.32 mg1L. <br />SAMPLE 4: Collection Pond <br />The total cyanide value by the manual method was 126 mg/L with a WAD CN value <br />determined at 112 mg/L. Copper cyanide, as CuiCNIZ is calculated to be 96 X 52/63 = 79 <br />mg/L. Zinc, nickel and manganese cyanide complexes account for a further between 1 and 3 <br />th,npier~ <br />