1992-05-27_REVISION - M1988112 (3)

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A 5 C I I.~ LS'Y'-:!Y„']'-41 ~ 90RW S T4 5. DATA EVALUATION: CYANIDE CHEMISTRY AT MAY 11, 7992 The objective of this part of the data evaluation is to establish the levels of total cyanide, weak acid dissociable cyanide and free cyanide in the tailings system, as of May 11, 1992. Based on the data evaluation in section 4 above, it is shown that none of the free cyanide values determined directly on the samples are correct. However, where necessary, it is possible to calculate the theoretical maximum ' potential cyanide levels from the database in Table 1 due to the fact that the metal levels, which are in chemical equilibrium with the cyanide these samples, were determined for the four samples. By assigning metals to their appropriate metallo- ' cyanide complexes, these can then be allocated to either the WAD cyanide or the total cyanide analyses. Consequently, the theoretical maximum free cyanide value may be determined by difference. ' Sample 1: Pre-detoxification ' - total cyanide - 385 mg/L - WAD cyanide - 358 mg/L - free cyanide - (WAD cyanide -minimum WAD metallo-cyanide complexes =maximum theoretical value for free cyanide) ' 358 - 170 = 188 ma/L Sample 2: Soigott ' - total cyanide - 290 mg/L ' - WAD cyanide - free cyanide - No consistent analysis (see Section 4.3- (WAD cyanide -minimum WAD metallo cyanide complexes =maximum theoretical value for free cyanide) ' No estimate Sample 3: Lower Pond - total cyanide - 189 mg/L - WAD cyanide - free cyanide - 166 mg/L (WAD cyanide -minimum WAD metallo cyanide complexes =maximum theoretical value for free cyanide) ' 166 - 134 = 32 mg/L 8