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I^ TABIF 12 CYANIDE DECAY IN ENTRAINED L1000R FIOLLOWING CYANIDE RECOVERY t+t C Pape 15 Parameter Inftlal t 1Neek . -,~_2 Weeks 4 Weeks ' _ 8 Weeks 12 Weeke pF1 10.2 9.7 ~~.;,~ .;:; '' 9.1 9.8 9.8 9.3 S04 252s 2526 2580 2530 2370 2390 Ca - 858 858 856 858 808 805 Total hardness 2140 2140 '2140 2140 2013 2008 (as CaCO~ Total CN 29.4 29.4 31.3 25.5 27 26 WAD CN 6.8 6.6 5.5 3.8 2.1 1.51 Cd 0.1 <0.01 <0.01 <0.01 <0.01 <0.01 co 0.33 o.2s o.z - - - Cu 6 4.3 2.9 2.1 0.63 0.16 Fe 8.7 8.9 9 9.3 9.3 9.5 Zn 0.01 0.03 0.01 <0.01 0.01 0.01 Pb <0.1 <0.1 <0.1 <0.1 - -- Mn 0.02 0.02 <0.01 0.01 0.02 0.02 Ag 0.04 0.01 0.01 0.02 0.02 0.02 Cr 0.02 - - <0.02 --- - Hg 0.0002 <0.0001 <0.0001 <0.0001 - - CYANIDE DECAY IN TAILINGS DECANT FOLLOWING CYANIDE RECOVERY t't Exposure Time ~ Total CfT WAD CN' Initial 10.2 - -- 29.4 6.8 1 day - 8.0 29.4 - 3 days 8.2 30.0 -- 7 days 8.3 30.0 --- 14 days 8.0 31.9 ---- 28 days 7.3 32.0 0.33 u! All values Irt mg/I, unless otherwise stated. _ .. The results of the laboratory and pilot plant Investigations have proven the viabilfty of the Cyanl;orb Process for recovery of cyanide from slurries. In addition to the recovery of cyanide, there were lurther environmental advantages relating to the disposal of tailings and the potential for groundwater contamination. The next section of the paper examines the economic aspects of cyanide recovery from solutions and slurries. ECONOMICS OF CYANIDE RECOVERY PROCESSES In applications where treatment of tailings prior to disposal Is warranted, there are several economic advantages to cyanide recovery systems. First, the operating costs associated with chemical treatment are eliminated, while second, a useful and expensive reagent (I.e. cyanide) Is recovered. The cost recovery more than offsets the cost of the cyanide recovery system. Third, the cyanide recovery systems are simple i,~ dasign and cperatlon, thereby minimizing operator requirements and the degree of automated contrd.