1992-04-07_REVISION - M1988112 - Laserfiche WebLink

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RPR 07 '92 03~03PM CVTOX 'N' CHEMICALS P.17i27 The Chemicals, known as CyTox 'N', closely resemble ferrous sulphate but contain a controlled amount of zinc to help in the formation of stable, insoluble end- products of CN' reaction. These solid solution chemicals are tailored to the site requirem@nts and the - particular operation. For example, in a settling pond we suggest th@ use of low- zinc CyTox. The shorter the pond-recycle time, the lower the Zinc bontent that is suggested. In leach-pad detox we suggest high zinc, which reactsimore slowly _ but forms insoluble Zn/Fe(CN) compounds that are stable across a wide range of pH while contributing neither Fe nor Zn to the ground water. 1 1rZ„ 1 vr~i,,t¢y~~~G.r - USE IN LEACH-PONDS 1, 7~ d~0 y ~J The use of a high (CyTox 11) and low (CyTox 6) level zinc compound will be - discussed to illustrate their differences. The "standard" used to edmpare CyTox 'N' effectiveness is ferrous sulphate (FeSO4.7H~0). _ As with ferrous sulphate, CyTox complexes CN and removes it from the pond by producing an insoluble compound. Most other processes rely upon oxidizing CN , but the associated casts are high and quite often the problems they produce are severe. Ferrous sulphate has been found to be satisfactory as a CN -neutralizing agent in ponds not only because it can produce very iow CN levels (10-20 ppm in practice) but also because it acts rapid]y and does not produce other problems when the pond water is recycled. CyTox performs equally well, but does so at lower cost and can leave a lot less - Fe in solution than does ferrous sulphate, ~ -, .,..,~ To illustrate the effectiveness of CyTox compounds,~Tables 1 and 1A are - presented. A deliberately high laadino of NaCN was added to deioniz@d water to produce a concentration of 206 ppm CN~. To this solution were added ferrous sulphate, Cy7ox 6 and CyTox 11 compounds in the amounts of 2 lbs per ton of ore equivalent, Figure 1 shows that CyTox 6 and ferrous sulphate fire nearly equivalent in their ability to neutralize CN whereas CyTox 11, although effective, is not quite as good. Figure 1A shows Fe in solution and clearly Cy7ox 11 is far superior to the other two compounds. Tests were also run in a gold producers laboratory using true tailings slurry. They were run at separate times on different slurries and hence the difference in starting CN° levels. Figure 2 shows the effectiveness of CyTox 6 compared to ferrous Sulphate ir, a siurry containing 130 ppm CN _ After six hours the results are close enough ~c be considered the same for CN neutralizing (92S vs 94a) and at 20 hour. t.".c neutralizinc for Cy7ox 6 and ferrous sulphate reach 97.2X and 98.8ro respectively. Again, one can see that soluble Fe remains at 40 ppm when ferrous s~lphate is .,n r.V ti„w Jww-n in 1 w-.. ..M-- ,+..T-.~ G ~.ww~!