with total cyanide at 15.2 ppm; At the end of optimization, the average destruction cost was 0.30$/t with total cyanide reduced to 0.14 ppm. Figure 5 - Caro’s Acid cost ($/t) Vs Total Cyanide in tailings dam (ppm). Optimization implies process improvement, higher product quality, cost reduction, and savings in foreign currency. In this case, cyanide destruction costs with Caro’s Acid averaged 0.93$/t of ore treated between 2002 and 2006 (before optimization). After optimization, destruction costs decreased to 0.30$/t of ore treated, yielding savings 0.63$/t. The average total cyanide content in the solution was 0.14 ppm, completely harmless and below Maximum Permissible Limits. Figure 6 - Caro’s Acid cost ($/t) in cyanide destruction. 6. CONCLUSIONS • The optimization of Caro’s Acid process for free cyanide destruction in CIP cyanidation tailings at the Antapite processing plant was achieved with a molar ratio H2SO4/H2O2 between 1.3 and 1.4. This reduced total cyanide in the tailings dam from an average of 15.2 ppm 1.22 0.87 0.70 0.84 1.02 0.91 0.61 0.42 0.30 18 17 16 12 13 6 1.68 0.31 0.14 0 4 8 12 16 20 0 0.4 0.8 1.2 1.6 2002 2003 2004 2005 2006 2007 2008 2009 2010 Caro’s Acid ($/t) Total NaCN (ppm) Caro’s Acid ($/t) Total NaCN (ppm) 1.22 0.87 0.70 0.84 1.02 0.91 0.61 0.42 0.30 0.93 0.93 0 0.2 0.4 0.6 0.8 1 1.2 1.4 2002 2003 2004 2005 2006 2007 2008 2009 2010 $/t Caro’s Acid Cost ($/t) Caro’s Acid Average Cost ($/t)
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