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j .. _. _ <br />:0:~: $d0{ 9~Sa:d SCI 4'.i\COL"tE.R • i~UOJ%OOi <br />A S C 1 <br />• nickel (as Ni1CN141: <br />equivalent amount of cyanide to form the Ni1CNl4 complex with 0.5 mg/L <br />nickel, is nickel 1571 multiplied by cyanide 1261 four times (108! i.e. 108/57 <br />= 1.895 which is about 1 mg/L. <br />• zinc 1 as ZnICN141: <br />equivalent amount of cyanide to form the ZnICN)4 complex with 1 .fi mg/L <br />zinc, is zinc 1651 times cyanide 126) four times (108) i.e, 108V65 1.fi6 <br />which is about 3 mg/L. <br />Based on the above metallo-complex speciation, the total amount of WAD Crll needed to <br />farm these complexes would he 176 mplL. Based on the analysed WAD CNi of 358 mg/L, <br />this implies a maximum theoretical cyanide level in the pre-detoxified tailings of 182 mg/L. <br />In practice, we have assumed that the copper cyanido iS as the Cu(CN12 coritplex. This is <br />unlikely to be the ease, as the most common form of capper cyanide complex in tailings <br />solutions is as CuiCN13, see Simovic end other workers, (1989 and others!. <br />If the capper values are recalculated for the Cu1CN13 complex, we would have the following <br />calculation: 208 X 78!63 = 257 mg/L. Adding the metallo-cyanide ccmplexes of zinc and <br />nickel, this would give a total of 261 mg/L, resulting in a residual maximum theoretical free <br />Cyanide value of 358 - 257 = 101 mg/L FCN. <br />SAMPLE 3: Lower Pand <br />This method is a repeat of the above calculation. Total cyanide by the manual method is <br />t89 mg/L. The WAD CN determination gave 166 mg/L. <br />Copper cyanide. as CulCN12, taking the lowest copper number, is 162 X 5x/63 = 133 <br />mg/I; nickel is the same as sample 1 at 1 mglL; zinc is 0.45 X 108/65 le$s than 1 mg/L; <br />which gives a total of 134 mg/L calculated metallo-cyanide WAO 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 mgiL. <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 mglL. Copper cyanide, as Cu1CN12 is calculated to be 9$ X 52/63 = 79 <br />mg/L. Zinc, nickel and manganese cyanide complexes account for a further between 1 and 3 <br />ir.~aa~i <br />