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