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<br />A S C I <br />' nickel las Ni1CN14): <br />equivalent amount of cyanide to form the Ni1CN14 complex With 0.5 mg/L <br />nickel, is nickel 1571 multiplied by cyanide (261 four times 11081 i.e. 108/57 <br />= 1.895 which is about 1 mg/L. <br />' zinc l as ZnICN14): <br />equivalent amount of cyanide to form the ZnICN)4 complex with 1.6 mg/L <br />zinc, is zinc (651 times cyanide 126) four times (1081 i.e. 10$/65 = 1.66 <br />which is about 3 mg/L. <br />Based on the above metallo-complex speciation, the total amount of WAD CN needed to <br />form these complexes would be 176 mg/L. Based on the analysed INAD 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 Cu1CNl2 complex. This is <br />unlikely to be the case, as the most common form of copper cyanide complex in tailings <br />solutions is as Cu1CN13, see Simovic and other workers, (1989 and othersl. <br />If the copper values are recalculated for the Cu1CN13 complex, we would haute the following <br />calculation: 208 X 78/63 = 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 mg/L FCN. <br />SAMPLE 3: Lower Pond <br />This method is a repeat of the above calculation. Total cyanide by the manual method is <br />189 mg/L. The WAD CN determination gave 166 mg/L. <br />Copper cyanide, as Cu1CNl2, taking the lowest copper number, is 162 X 52/63 = 133 <br />mg/I; nickel is the same as sample 1 at 1 mg/L; zinc is 0.45 X 108/65 =less than 1 mg/L; <br />which gives a total of 134 mg/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 mg/L. <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 Cu1CN)2 is calculated to be 96 X 52/63 = 79 <br />mg/L. Zinc, nickel and manganese cyanide complexes account for a further bdtween 1 and 3 <br />~rma~~ <br />