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SENT BY:PMHS : 5-26-92 ~ 13:35 ~ 303~3040-+CO MI~ED LAND REC'L ~3f 3 <br />A - C I <br />btJ~:~5Y:.111B~4RAS.:TISM,.M1'!.''Pn <br />6. DATA EVALUATION: CYANIDE CHEMISTRY AT MAY 11, 1992 <br />The objective of this pert 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 sfhown that <br />none of the free cyanide values determined directly on the samples ary correct. <br />However, where neCelssary, it is possible t0 calculate the theoretical ~meximum <br />potential cyanide levels from the database in Table 1 due to the fact that the metal <br />levels, wh(ch are in chemical equilibrium with the cyanide these sam es, were <br />determined far the four samples. By assigning metals to their apprapriat metallo- <br />cyanide compiexes, these can then be allocated to either the WAD cyanide or the <br />total cyanide analyses. Consequently, the theoretical maximum free cya~ida value <br />may be determined by difference. <br />Samgle 1: Pra-detoxification <br />- total cyanide - 385 mg/L <br />- WAD cyanide - 368 mg/L <br />- free cyanide - (WAD cyanide • minimum WAD metello-CyB~ide <br />complexes =maximum theoretical value for free <br />cyanide) <br />358 - 170 = 188 rna/L <br />Samole 2: Soiaott <br />• total Cyanide - 290 mg/L <br />- WAD cyanide - No consistent analysis (see Section 4.3) <br />• free cyanide - (WAb cyanide -minimum WAD metello-cyar:fide <br />complexes =maximum theoretical value for free <br />cyanide) <br />No estimate <br />- total cyanide - 189 mg/L <br />- WAD cyanide - 166 mg/L <br />- free cyanide - (WAD Cyanide -minimum WAD metello cyanide <br />complexes =maximum theoretical value for free <br />cyanide) <br />166 - 134 = 32 ma/L <br />8 <br />